阅读说明：本技术 一种励磁控制器控制方法及系统 (Excitation controller control method and system ) 是由 高红亮 詹习生 朱军 杨青胜 肖凌俊 徐丰 于 2020-06-15 设计创作，主要内容包括：本发明涉及一种励磁控制器控制方法及系统,涉及电力系统稳定性控制技术领域。该方法包括：利用PID控制和励磁控制系统数学模型确定控制策略的参数；利用励磁控制系统的第k次采样误差值、第k次采样误差值与第k-1次采样误差值的第一误差差值以及第k-1次采样误差值与第k-2次采样误差值的第二误差差值确定励磁控制器当前状态对应的预设控制条件；采用当前状态对应的预设控制条件对应的控制策略控制励磁控制器的输出。本发明的励磁控制器控制方法及系统可根据励磁控制系统的工作状态及误差情况自动确定不同的预设控制条件,使控制策略更加灵活；自动调整励磁控制器的参数,提高了励磁控制器的适应性,使励磁控制系统的控制效果更好。(The invention relates to a control method and a control system for an excitation controller, and relates to the technical field of stability control of a power system. The method comprises the following steps: determining parameters of a control strategy by using a PID control and excitation control system mathematical model; determining a preset control condition corresponding to the current state of the excitation controller by using a kth sampling error value of the excitation control system, a first error difference value of the kth sampling error value and a kth-1 sampling error value, and a second error difference value of the kth-1 sampling error value and a kth-2 sampling error value; and controlling the output of the excitation controller by adopting a control strategy corresponding to the preset control condition corresponding to the current state. The excitation controller control method and the excitation controller control system can automatically determine different preset control conditions according to the working state and the error condition of the excitation control system, so that the control strategy is more flexible; the parameters of the excitation controller are automatically adjusted, the adaptability of the excitation controller is improved, and the control effect of an excitation control system is better.)

1. A method of controlling an excitation controller, comprising:

acquiring a mathematical model of an excitation control system;

determining parameters of a control strategy of the excitation controller by using PID control and the mathematical model of the excitation control system; the parameters include: a proportionality coefficient, an integral coefficient, and a differential coefficient;

determining a difference value between an error value of a k-th sampling of an excitation control system and a first error value of a k-1-th sampling as a first error difference value, and determining a difference value between the first error value and a second error value of the k-2-th sampling as a second error difference value; wherein k represents the number of samples;

determining a preset control condition corresponding to the current state of the excitation controller by using the error value in the k-th sampling, the first error difference value and the second error difference value; the preset control conditions include: the control method comprises the following steps of (1) carrying out first preset control conditions, second preset control conditions, third preset control conditions, fourth preset control conditions and fifth preset control conditions;

and controlling the output of the excitation controller by adopting a control strategy corresponding to a preset control condition corresponding to the current state.

2. The excitation controller control method according to claim 1, wherein the determining the preset control condition corresponding to the current state of the excitation controller by using the error value at the k-th sampling, the first error difference value, and the second error difference value specifically includes:

judging whether the absolute value of the error value in the k-th sampling is larger than a first preset error threshold value or not to obtain a first judgment result;

if the first judgment result is yes, the preset control condition corresponding to the current state is a first preset control condition;

if the first judgment result is negative, judging whether the product of the error value in the k-th sampling and the first error difference value is larger than zero or whether the first error difference value is equal to zero, and obtaining a second judgment result;

if the second judgment result is yes, the preset control condition corresponding to the current state is a second preset control condition;

if the second judgment result is negative, judging whether the product of the error value during the k-th sampling and the first error difference value is smaller than zero and whether the product of the first error difference value and the second error difference value is larger than zero or whether the error value during the k-th sampling is equal to zero to obtain a third judgment result;

if the third judgment result is yes, the preset control condition corresponding to the current state is a third preset control condition;

if the third judgment result is negative, judging whether the product of the error value in the k-th sampling and the first error difference value is smaller than zero and whether the product of the first error difference value and the second error difference value is smaller than zero to obtain a fourth judgment result;

if the fourth judgment result is yes, the preset control condition corresponding to the current state is a fourth preset control condition;

if the fourth judgment result is negative, judging whether the absolute value of the error value in the k-th sampling is smaller than the preset precision of the excitation control system error or not, and obtaining a fifth judgment result;

if the fifth judgment result is yes, the preset control condition corresponding to the current state is a fifth preset control condition.

3. The excitation controller control method according to claim 1 or 2, wherein when the preset control condition corresponding to the current state is a first preset control condition, the controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state specifically includes:

and determining the output of the excitation controller as a preset value, and performing open-loop control on the excitation control system.

4. The excitation controller control method according to claim 1 or 2, wherein when the preset control condition corresponding to the current state is a second preset control condition, the controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state specifically includes:

judging whether the absolute value of the error value in the k-th sampling is greater than or equal to a second preset error threshold value or not to obtain a sixth judgment result;

if the sixth determination result is yes, u (K-1) + K is determined according to the formula u (K)₁K_pe (k) determining the output of the excitation controller; wherein u (K) represents an output of the excitation controller, u (K-1) represents an output of the excitation controller at the K-1 th sampling, and K₁Represents the amplification factor, K, of the excitation control system_pRepresents the scaling factor, e (k) represents the error value at the k-th sampling;

if the sixth determination result is no, u (K-1) + K according to the formula u (K)₂K_pe (k) determining the output of the excitation controller; wherein, K₂Represents a suppression coefficient of the excitation control system.

5. The excitation controller control method according to claim 1 or 2, wherein when the preset control condition corresponding to the current state is a third preset control condition, the controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state specifically includes:

the output of the excitation controller is held.

6. The excitation controller control method according to claim 1 or 2, wherein when the preset control condition corresponding to the current state is a fourth preset control condition, the controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state specifically includes:

judging whether the absolute value of the error value in the k-th sampling is greater than or equal to the second preset error threshold value or not to obtain a seventh judgment result;

if the seventh determination result is yes, u (K) -u (K-1) + K is determined according to the formula u (K)₁K_pe (k-1) determining an output of the excitation controller; wherein u (K) represents an output of the excitation controller, u (K-1) represents an output of the excitation controller at the K-1 th sampling, and K₁Represents the amplification factor, K, of the excitation control system_pRepresenting the scaling factor, e (k-1) representing the first error value;

if the seventh determination result is no, u (K-1) + K according to the formula u (K)₂K_pe (k-1) determining an output of the excitation controller; wherein, K₂Represents a suppression coefficient of the excitation control system.

7. The excitation controller control method according to claim 1 or 2, wherein when the preset control condition corresponding to the current state is a fifth preset control condition, the controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state specifically includes:

according to the formulaDetermining an output of the excitation controller; wherein u (K) represents the output of the excitation controller, K_pRepresents the aboveA scaling factor e (K) representing an error value at the K-th sampling, K_iRepresenting the integral coefficient, j representing the number of samples, e (j) representing the error value at the j-th sample, K_dRepresents the differential coefficient, and Δ e (k) represents a first error difference.

8. An excitation controller control system, comprising:

the mathematical model acquisition module is used for acquiring a mathematical model of the excitation control system;

the parameter determining module is used for determining parameters of a control strategy of the excitation controller by utilizing PID control and the excitation control system mathematical model; the parameters include: a proportionality coefficient, an integral coefficient, and a differential coefficient;

the difference value determining module is used for determining the difference value between the error value of the excitation control system in the k sampling and the first error value in the k-1 sampling as a first error difference value, and determining the difference value between the first error value and the second error value in the k-2 sampling as a second error difference value; wherein k represents the number of samples;

the preset control condition determining module is used for determining a preset control condition corresponding to the current state of the excitation controller by using the error value in the k-th sampling, the first error difference value and the second error difference value; the preset control conditions include: the control method comprises the following steps of (1) carrying out first preset control conditions, second preset control conditions, third preset control conditions, fourth preset control conditions and fifth preset control conditions;

and the control excitation controller output module is used for controlling the output of the excitation controller by adopting a control strategy corresponding to the preset control condition corresponding to the current state.

9. The excitation controller control system according to claim 8, wherein the preset control condition determining module specifically includes:

the first judgment unit is used for judging whether the absolute value of the error value in the k-th sampling is larger than a first preset error threshold value or not to obtain a first judgment result;

a first preset control condition determining unit, configured to determine that the preset control condition corresponding to the current state is a first preset control condition when the first determination result is yes;

a second judging unit, configured to, when the first judgment result is negative, judge whether a product of the error value at the kth sampling and the first error difference value is greater than zero or whether the first error difference value is equal to zero, to obtain a second judgment result;

a second preset control condition determining unit, configured to determine that the preset control condition corresponding to the current state is a second preset control condition when the second determination result is yes;

a third determining unit, configured to determine, when the second determination result is negative, whether a product of the error value during the kth sampling and the first error difference value is smaller than zero and whether a product of the first error difference value and the second error difference value is greater than zero, or whether the error value during the kth sampling is equal to zero, so as to obtain a third determination result;

a third preset control condition determining unit, configured to determine that the preset control condition corresponding to the current state is a third preset control condition when the third determination result is yes;

a fourth judging unit, configured to, when the third judgment result is negative, judge whether a product of the error value at the k-th sampling and the first error difference value is smaller than zero and a product of the first error difference value and the second error difference value is smaller than zero, to obtain a fourth judgment result;

a fourth preset control condition determining unit, configured to determine that the preset control condition corresponding to the current state is a fourth preset control condition when the fourth determination result is yes;

a fifth judging unit, configured to, when the fourth judging result is negative, judge whether an absolute value of the error value at the time of the kth sampling is smaller than a preset accuracy of an error of an excitation control system, to obtain a fifth judging result;

and a fifth preset control condition determining unit, configured to, when the fifth determination result is yes, determine that the preset control condition corresponding to the current state is a fifth preset control condition.

10. The excitation controller control system according to claim 8 or 9, wherein the excitation controller output control module specifically includes:

and the open-loop control unit is used for determining the output of the excitation controller as a preset value and performing open-loop control on the excitation control system when the preset control condition corresponding to the current state is a first preset control condition.

Technical Field

The invention relates to the technical field of stability control of power systems, in particular to a method and a system for controlling an excitation controller.

Background

The stability of the power system has an important influence on the safety and reliability of a power grid, and the stability of the power system is enhanced through various measures, so that the method has very important significance on the healthy development of social economy and the improvement of the life quality of people. The excitation controller is the core of a synchronous generator control system, can effectively control a generator excitation system, and is an important measure for enabling a power system to stably operate. Although the application of conventional PID control (proportional-integral-derivative control) to the excitation controller is very mature, the excitation controller adopting such a control mode has fixed parameters and a single control law, and cannot automatically change the excitation control law according to the working state and error condition of the generator excitation system and adjust the parameters of the excitation controller, so that the capability of the excitation controller to adapt to the characteristics of an object is poor. Therefore, the existing excitation controller has the problem of poor adaptability.

Disclosure of Invention

The invention aims to provide a control method and a control system of an excitation controller, which solve the problem of poor adaptability of the existing excitation controller.

In order to achieve the purpose, the invention provides the following scheme:

an excitation controller control method comprising:

acquiring a mathematical model of an excitation control system;

determining parameters of a control strategy of the excitation controller by using PID control and the mathematical model of the excitation control system; the parameters include: a proportionality coefficient, an integral coefficient, and a differential coefficient;

determining a difference value between an error value of a k-th sampling of an excitation control system and a first error value of a k-1-th sampling as a first error difference value, and determining a difference value between the first error value and a second error value of the k-2-th sampling as a second error difference value; wherein k represents the number of samples;

determining a preset control condition corresponding to the current state of the excitation controller by using the error value in the k-th sampling, the first error difference value and the second error difference value; the preset control conditions include: the control method comprises the following steps of (1) carrying out first preset control conditions, second preset control conditions, third preset control conditions, fourth preset control conditions and fifth preset control conditions;

and controlling the output of the excitation controller by adopting a control strategy corresponding to a preset control condition corresponding to the current state.

Optionally, the determining, by using the error value at the kth sampling, the first error difference value, and the second error difference value, a preset control condition corresponding to the current state of the excitation controller specifically includes:

judging whether the absolute value of the error value in the k-th sampling is larger than a first preset error threshold value or not to obtain a first judgment result;

if the first judgment result is yes, the preset control condition corresponding to the current state is a first preset control condition;

if the first judgment result is negative, judging whether the product of the error value in the k-th sampling and the first error difference value is larger than zero or whether the first error difference value is equal to zero, and obtaining a second judgment result;

if the second judgment result is yes, the preset control condition corresponding to the current state is a second preset control condition;

if the second judgment result is negative, judging whether the product of the error value during the k-th sampling and the first error difference value is smaller than zero and whether the product of the first error difference value and the second error difference value is larger than zero or whether the error value during the k-th sampling is equal to zero to obtain a third judgment result;

if the third judgment result is yes, the preset control condition corresponding to the current state is a third preset control condition;

if the third judgment result is negative, judging whether the product of the error value in the k-th sampling and the first error difference value is smaller than zero and whether the product of the first error difference value and the second error difference value is smaller than zero to obtain a fourth judgment result;

if the fourth judgment result is yes, the preset control condition corresponding to the current state is a fourth preset control condition;

if the fourth judgment result is negative, judging whether the absolute value of the error value in the k-th sampling is smaller than the preset precision of the excitation control system error or not, and obtaining a fifth judgment result;

if the fifth judgment result is yes, the preset control condition corresponding to the current state is a fifth preset control condition.

Optionally, when the preset control condition corresponding to the current state is a first preset control condition, the controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state specifically includes:

and determining the output of the excitation controller as a preset value, and performing open-loop control on the excitation control system.

Optionally, when the preset control condition corresponding to the current state is a second preset control condition, the controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state specifically includes:

judging whether the absolute value of the error value in the k-th sampling is greater than or equal to a second preset error threshold value or not to obtain a sixth judgment result;

if the sixth determination result is yes, u (K-1) + K is determined according to the formula u (K)₁K_pe (k) determining the output of the excitation controller; wherein u (K) represents an output of the excitation controller, u (K-1) represents an output of the excitation controller at the K-1 th sampling, and K₁Represents the amplification factor, K, of the excitation control system_pRepresents the scaling factor, e (k) represents the error value at the k-th sampling;

if the sixth determination result is no, u (K-1) + K according to the formula u (K)₂K_pe (k) determining said excitationAn output of the controller; wherein, K₂Represents a suppression coefficient of the excitation control system.

Optionally, when the preset control condition corresponding to the current state is a third preset control condition, the controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state specifically includes:

the output of the excitation controller is held.

Optionally, when the preset control condition corresponding to the current state is a fourth preset control condition, the controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state specifically includes:

judging whether the absolute value of the error value in the k-th sampling is greater than or equal to the second preset error threshold value or not to obtain a seventh judgment result;

if the seventh determination result is yes, u (K) -u (K-1) + K is determined according to the formula u (K)₁K_pe (k-1) determining an output of the excitation controller; wherein u (K) represents an output of the excitation controller, u (K-1) represents an output of the excitation controller at the K-1 th sampling, and K₁Represents the amplification factor, K, of the excitation control system_pRepresenting the scaling factor, e (k-1) representing the first error value;

if the seventh determination result is no, u (K-1) + K according to the formula u (K)₂K_pe (k-1) determining an output of the excitation controller; wherein, K₂Represents a suppression coefficient of the excitation control system.

Optionally, when the preset control condition corresponding to the current state is a fifth preset control condition, the controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state specifically includes:

according to the formula

Determining an output of the excitation controller; wherein u (K) represents the output of the excitation controller, K_pRepresenting the scaling factor, e (K) representing the error value at the K-th sampling, K_iRepresenting the integral coefficient, j representing the number of samples, e (j) representing the error value at the j-th sample, K_dRepresents the differential coefficient, and Δ e (k) represents a first error difference.

An excitation controller control system comprising:

the mathematical model acquisition module is used for acquiring a mathematical model of the excitation control system;

the parameter determining module is used for determining parameters of a control strategy of the excitation controller by utilizing PID control and the excitation control system mathematical model; the parameters include: a proportionality coefficient, an integral coefficient, and a differential coefficient;

the difference value determining module is used for determining the difference value between the error value of the excitation control system in the k sampling and the first error value in the k-1 sampling as a first error difference value, and determining the difference value between the first error value and the second error value in the k-2 sampling as a second error difference value; wherein k represents the number of samples;

the preset control condition determining module is used for determining a preset control condition corresponding to the current state of the excitation controller by using the error value in the k-th sampling, the first error difference value and the second error difference value; the preset control conditions include: the control method comprises the following steps of (1) carrying out first preset control conditions, second preset control conditions, third preset control conditions, fourth preset control conditions and fifth preset control conditions;

and the control excitation controller output module is used for controlling the output of the excitation controller by adopting a control strategy corresponding to the preset control condition corresponding to the current state.

Optionally, the preset control condition determining module specifically includes:

the first judgment unit is used for judging whether the absolute value of the error value in the k-th sampling is larger than a first preset error threshold value or not to obtain a first judgment result;

a first preset control condition determining unit, configured to determine that the preset control condition corresponding to the current state is a first preset control condition when the first determination result is yes;

a second judging unit, configured to, when the first judgment result is negative, judge whether a product of the error value at the kth sampling and the first error difference value is greater than zero or whether the first error difference value is equal to zero, to obtain a second judgment result;

a second preset control condition determining unit, configured to determine that the preset control condition corresponding to the current state is a second preset control condition when the second determination result is yes;

a third determining unit, configured to determine, when the second determination result is negative, whether a product of the error value during the kth sampling and the first error difference value is smaller than zero and whether a product of the first error difference value and the second error difference value is greater than zero, or whether the error value during the kth sampling is equal to zero, so as to obtain a third determination result;

a third preset control condition determining unit, configured to determine that the preset control condition corresponding to the current state is a third preset control condition when the third determination result is yes;

a fourth judging unit, configured to, when the third judgment result is negative, judge whether a product of the error value at the k-th sampling and the first error difference value is smaller than zero and a product of the first error difference value and the second error difference value is smaller than zero, to obtain a fourth judgment result;

a fourth preset control condition determining unit, configured to determine that the preset control condition corresponding to the current state is a fourth preset control condition when the fourth determination result is yes;

a fifth judging unit, configured to, when the fourth judging result is negative, judge whether an absolute value of the error value at the time of the kth sampling is smaller than a preset accuracy of an error of an excitation control system, to obtain a fifth judging result;

and a fifth preset control condition determining unit, configured to, when the fifth determination result is yes, determine that the preset control condition corresponding to the current state is a fifth preset control condition.

Optionally, the control excitation controller output module specifically includes:

and the open-loop control unit is used for determining the output of the excitation controller as a preset value and performing open-loop control on the excitation control system when the preset control condition corresponding to the current state is a first preset control condition.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects:

the invention provides a control method and a control system for an excitation controller. The method comprises the following steps: acquiring a mathematical model of an excitation control system; determining parameters of a control strategy of an excitation controller by using a PID control and excitation control system mathematical model; the parameters include: a proportionality coefficient, an integral coefficient, and a differential coefficient; determining the difference value between the error value of the excitation control system during the kth sampling and the first error value during the (k-1) th sampling as a first error difference value, and determining the difference value between the first error value and the second error value during the (k-2) th sampling as a second error difference value; wherein k represents the number of samples; determining a preset control condition corresponding to the current state of the excitation controller by using the error value in the k-th sampling, the first error difference value and the second error difference value; the preset control conditions include: the control method comprises the following steps of (1) carrying out first preset control conditions, second preset control conditions, third preset control conditions, fourth preset control conditions and fifth preset control conditions; and controlling the output of the excitation controller by adopting a control strategy corresponding to the preset control condition corresponding to the current state. The excitation controller control method and the excitation controller control system can automatically determine different excitation control laws according to the working state and the error condition of the excitation control system, namely preset control conditions, so that the control strategy is more flexible; the parameters of the excitation controller are automatically adjusted, the adaptability of the excitation controller is improved, the adaptability of the excitation controller is stronger, the characteristic of intelligent control is embodied, and the control effect of an excitation control system is better.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

Fig. 1 is a flowchart of a control method of an excitation controller according to an embodiment of the present invention;

fig. 2 is a structural diagram of a synchronous generator excitation control system provided in an embodiment of the present invention;

fig. 3 is a block diagram of an excitation controller control system according to an embodiment of the present invention;

FIG. 4 is a graph of the output response of an excitation system provided by an embodiment of the invention;

fig. 5 is a graph illustrating an error variation of an excitation system according to an embodiment of the present invention;

fig. 6 is a graph showing a variation of a control amount of the excitation system according to the embodiment of the present invention.

Description of the symbols: 1. an excitation controller; 2. a power amplifying unit; 3. a synchronous generator; 4. a voltage measuring unit.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a control method and a control system of an excitation controller, which solve the problem of poor adaptability of the existing excitation controller.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

The present embodiment provides a method for controlling an excitation controller, fig. 1 is a flowchart of the method for controlling the excitation controller according to the present embodiment, and referring to fig. 1, the method for controlling the excitation controller includes:

step 101, obtaining a mathematical model of an excitation control system. The excitation control system of this embodiment is a synchronous generator excitation control system, and before determining the control method of the excitation controller, the composition of each link of the synchronous generator excitation control system needs to be analyzed to obtain the transfer function of the synchronous generator excitation control system, so as to obtain the mathematical model of the synchronous generator excitation control system.

Fig. 2 is a structural diagram of a synchronous generator excitation control system according to an embodiment of the present invention. Referring to fig. 2, the excitation control system includes: the excitation control device 1, the power amplification unit 2, the synchronous generator 3 and the voltage measurement unit 4. The output end of the excitation controller 1 is connected with the input end of the power amplification unit 2, the output end of the power amplification unit 2 is connected with the input end of the synchronous generator 3, the input end of the voltage measurement unit 4 is connected with the output end of the synchronous generator 3, and the output end of the voltage measurement unit 4 is connected with the input end of the excitation controller 1.

The power amplification mainly refers to the power conversion function between a small control signal output by an excitation controller and the output of an excitation power device, and a power amplification unit can be regarded as a first-order inertia link, and the transfer function of the power amplification unit is as follows:

in the formula (1), G₁(s) represents the transfer function of the power amplification unit, s represents a complex field variable, K_ATo amplify the voltage ratio of the link, T_AIs the time constant of the amplification stage.

Under the condition of only researching an excitation control system and without considering the saturation characteristic of a magnetic circuit of the generator, the transfer function of the synchronous generator can be simplified into the following first-order inertia link:

in the formula (2), G₂(s) represents the transfer function of the synchronous generator, K_GFor the amplification factor of the generator，T_GIs the generator time constant.

The voltage measurement unit completes the conversion from the output voltage of the synchronous generator to the input signal of the excitation controller, and can be described by a first-order inertia link, and the transfer function of the voltage measurement unit can be represented by the following formula:

in the formula (3), G₃(s) represents the transfer function of the voltage measuring cell, K₃Is a voltage proportionality coefficient, T₃To measure the loop time constant.

The mathematical model of the controlled object in the excitation control system can be obtained as follows:

wherein G(s) represents a transfer function of a mathematical model of a controlled object in the excitation control system, K_ATo amplify the voltage ratio of the link, T_ATo amplify the time constant of the element, s denotes a complex field variable, K_GFor the amplification factor of the synchronous generator, T_GIs the time constant of the synchronous generator.

The controlled objects of the present embodiment are a power amplifying unit and a synchronous generator, and the purpose of step 101 is to give the specific form of the controlled object, i.e. to give the controlled object in the form of a transfer function. The excitation controller controls the controlled object, the excitation controller control method is specific to the mathematical model of the controlled object, the specific parameters of the excitation controller can be determined only by knowing the mathematical model of the controlled object, so the parameters need to be established on the basis of knowing the mathematical model of the controlled object, and the parameters comprise: proportional coefficient, integral coefficient, differential coefficient, integral time constant, differential time constant, sampling time, and upper limit value S of control quantity₁Lower limit value S of control amount₂A first predetermined error threshold L₁And a second predetermined error threshold L₂。

Step 102, control and excitation by PIDA control system mathematical model, which determines parameters of a control strategy of the excitation controller; the parameters include: proportional coefficient, integral coefficient, differential coefficient, integral time constant, differential time constant, sampling time, and upper limit value S of control quantity₁Lower limit value S of control amount₂A first predetermined error threshold L₁And a second predetermined error threshold L₂. In practical application, parameters of the control strategy of the excitation controller are obtained by performing a simulation experiment of conventional PID control on a mathematical model of a controlled object.

After the PID controller is added into the excitation control system, a step signal is applied to the input end of the excitation control system, and the output response curve, the change curve of the control quantity, the change curve of the error and the like of the excitation control system can be observed through the oscilloscope after the response of the excitation control system. Determining the upper limit value S of the controlled variable by the variation curve of the controlled variable₁And a lower limit value S₂To achieve saturation processing of the control quantity; determining a first predetermined error threshold value L from a curve of the error₁And a second predetermined error threshold L₂. The error is an error e (k) of the excitation control system, and a deviation between an input r (k) of the excitation control system and an output y (k) of the excitation control system, that is, e (k) r (k) -y (k). The maximum value of the error of the excitation control system can be obtained through the variation curve of the error, and in the embodiment, the maximum value of the error is 1, and L is₁Taking the error as 80 percent of the maximum value, namely 0.8; l is₂Taking the error as 5 percent of the maximum value, namely 0.05; l is₁Is a large error threshold, i.e. when the error is greater than L₁When the error is large, the error is considered to be large; l is₂Is a larger error threshold, i.e. when the error is larger than L₂The error is considered to be large.

And controlling the excitation control system by using a PID control method, determining the output of the excitation controller and further obtaining the parameters of the excitation controller.

Wherein the content of the first and second substances,

in the above formula, u' (k) represents the output of the excitation controller when the PID control method is employed; k_pIs a proportionality coefficient; e (k) represents an error value at the k-th sampling; k_iIs an integral coefficient; j and k both represent sampling times, j represents j sampling time, k represents k sampling time, and j is more than or equal to 0 and less than or equal to k; e (j) represents an error value of the excitation control system at the j sampling time; k_dIs a differential coefficient; Δ e (k) represents an error difference value between an error value at the k-th sampling time and an error value at the k-1-th sampling time of the excitation control system; t is sampling time; t is_iIs an integration time constant; t is_dIs the differential time constant.

103, determining a difference value between an error value of the excitation control system during the kth sampling and a first error value of the excitation control system during the kth-1 sampling as a first error difference value, and determining a difference value between the first error value and a second error value of the excitation control system during the kth-2 sampling as a second error difference value; where k represents the number of samples.

Step 103 specifically comprises: and obtaining an error value of the excitation control system during sampling at the kth time, a first error value during sampling at the kth-1 time and a second error value during sampling at the kth-2 time.

The difference between the error value at the k-th sampling and the first error value is determined as a first error difference value, i.e., [ delta ] e (k) [ < e >) [ k ] [ ([ k ] ]) e (k-1), where [ delta ] e (k) ] represents the first error difference value, e (k) represents the error value at the k-th sampling, and e (k-1) represents the first error value.

The difference between the first error value and the second error value is determined as a second error difference value, i.e., Δ e (k-1) ═ e (k-1) -e (k-2), Δ e (k-1) represents the second error difference value, and e (k-2) represents the second error value.

104, determining a preset control condition corresponding to the current state of the excitation controller by using the error value in the k-th sampling, the first error difference value and the second error difference value; the preset control conditions include: the control method comprises the following steps of first preset control conditions, second preset control conditions, third preset control conditions, fourth preset control conditions and fifth preset control conditions.

Step 104 specifically includes:

and judging whether the absolute value of the error value in the k-th sampling is greater than a first preset error threshold value or not to obtain a first judgment result.

If the first judgment result is yes, the preset control condition corresponding to the current state is the first preset control condition.

If the first judgment result is negative, whether the product of the error value in the k-th sampling and the first error difference value is larger than zero or whether the first error difference value is equal to zero is judged, and a second judgment result is obtained.

If the second judgment result is yes, the preset control condition corresponding to the current state is the second preset control condition, and the second judgment result is e (k) △ e (k)>0 or △ e (k) 0, i.e. (1)

Or (2)

Or (3) e (k) -e (k-1) ═ 0. For (1), it means that the error value at the k-th sampling is positive, and when increasing, the absolute value of the error value at the k-th sampling is increasing; for (2), it indicates that the error value at the k-th sampling is negative and continues to decrease, and the absolute value of the error value at the k-th sampling increases; the error is unchanged for (3).

If the second judgment result is negative, whether the product of the error value in the k-th sampling and the first error difference value is smaller than zero and whether the product of the first error difference value and the second error difference value is larger than zero or whether the error value in the k-th sampling is equal to zero is judged, and a third judgment result is obtained.

If the third judgment result is yes, the preset control condition corresponding to the current state is a third preset control condition. The third determination result is e (k) Δ e (k) <0 and Δ e (k) > e (k-1) >0, or e (k) >0, i.e., (1) e (k-2) < e (k-1) < e (k) <0 or (2)0< e (k) < e (k-1) < e (k-2) or (3) r (k) -y (k) >0, where (1) and (2) mean that the absolute value of the error changes in a direction toward decrease, and (3) mean that the error has reached an equilibrium state.

If the third judgment result is negative, whether the product of the error value and the first error difference value in the k-th sampling is smaller than zero and whether the product of the first error difference value and the second error difference value is smaller than zero is judged, and a fourth judgment result is obtained.

If the fourth judgment result is yes, the preset control condition corresponding to the current state is the fourth preset control condition, and the fourth judgment result is e (k) △ e (k)<0 and △ e (k) △ e (k-1)<0, i.e. (1)0<e(k)<e(k-1)>e (k-2) or (2)(1) And (2) both mean that the error is in an extreme state.

If the fourth judgment result is negative, judging whether the absolute value of the error value in the k-th sampling is smaller than the preset precision of the excitation control system error, and obtaining a fifth judgment result.

If the fifth judgment result is yes, the preset control condition corresponding to the current state is a fifth preset control condition. The fifth judgment result is that the error is | e (k) | <, which is the preset precision of the excitation control system error, and indicates that the error is very small, and an integral link can be added into the excitation controller to reduce the steady-state error.

And 105, controlling the output of the excitation controller by adopting a control strategy corresponding to the preset control condition corresponding to the current state.

Step 105 specifically includes:

when the preset control condition corresponding to the current state is a first preset control condition, controlling the output of the excitation controller by using a control strategy corresponding to the preset control condition corresponding to the current state, specifically comprising: and determining the output of the excitation controller as a preset value, and performing open-loop control on an excitation control system. And adjusting the control quantity output by the excitation controller to a preset value, and performing open-loop control on the excitation control system.

The error value at the k-th sampling exceeds the maximum of the error of the excitation control system80% of the value, i.e. above L₁Then, the control amount is controlled to the upper limit value S of the control amount₁It is given. This example will apply to L₁The value of (A) is thinned to 80%, 60%, 40%, 20% or 1% of the maximum value of the error. Upper limit value S of control amount₁And L₁Correspondingly, i.e. when the error value at the k-th sampling is greater than 80%, 60%, 40%, 20% or 1% of the maximum value of the error of the excitation control system (L)₁80%, 60%, 40%, 20% or 1% of the maximum error value, respectively), and the upper limit value S of the controlled variable₁Respectively 100,80,40,10 or 0.1, i.e. the preset values of the control quantity output respectively correspond to: 100,80,40,10 or 0.1. S when the error value of the k sampling is greater than 80% of the maximum error value₁100; s when the error value of the k sampling is larger than 60% of the maximum error value₁80; s when the error value of the k-th sampling is larger than 40% of the maximum error value₁40; s when the error value of the k-th sampling is greater than 20% of the maximum error value₁10; s when the error value of the k-th sampling is larger than 1% of the maximum error value₁0.1. This embodiment combines only L₁Is refined to 5 values of 80%, 60%, 40%, 20% or 1% of the maximum error value, but L₁Is not limited to these 5 values, L₁The value of (A) can be adjusted according to actual needs, and L can be adjusted₁Is subdivided into more than 5 values or less than 5 values.

When the preset control condition corresponding to the current state is a second preset control condition, controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state, specifically including:

and judging whether the absolute value of the error value in the k-th sampling is greater than or equal to a second preset error threshold value or not, and obtaining a sixth judgment result.

If the sixth determination result is yes, u (K-1) + K is determined according to the formula u (K)₁K_pe (k) determining the output of the excitation controller; wherein u (K) represents the output of the excitation controller, u (K-1) represents the output of the excitation controller at the time of sampling at the K-1 th time, and K₁Representing the amplification factor, K, of the excitation control system₁>1，K_pRepresents the scaling factor, and e (k) represents the error value at the k-th sampling. The sixth determination result is that the error is large because the error changes in a direction in which the absolute value of the error increases, and a strong control action needs to be performed by the excitation controller to quickly reduce the absolute value of the error.

If the sixth determination result is no, u (K-1) + K according to the formula u (K)₂K_pe (k) determining the output of the excitation controller; wherein, K₂Representing the suppression factor, K, of the excitation control system₂<1. If the sixth determination result is no, the error is not so large although it changes in a direction in which the absolute value of the error increases.

When the preset control condition corresponding to the current state is a third preset control condition, controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state, specifically including: the output of the excitation controller is maintained. The output of the excitation controller may remain unchanged, i.e. u (k) ═ u (k).

When the preset control condition corresponding to the current state is a fourth preset control condition, controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state, specifically including:

and judging whether the absolute value of the error value in the k-th sampling is greater than or equal to a second preset error threshold value or not to obtain a seventh judgment result.

If yes, u (K-1) + K is determined according to the formula u (K)₁K_pe (k-1) determining the output of the excitation controller; where e (k-1) represents a first error value. The seventh determination result is yes, which indicates that the absolute value of the error is large at this time, and the excitation controller can perform a strong control action.

If the seventh determination result is no, u (K-1) + K according to the formula u (K)₂K_pe (k-1) determines the output of the excitation controller. If the seventh determination result is no, the absolute value of the error is small, and the excitation controller can perform a weak control action.

When the preset control condition corresponding to the current state is a fifth preset control condition, controlling the output of the excitation controller by using the control strategy corresponding to the preset control condition corresponding to the current state, specifically including:

according to the formula

Determining an output of an excitation controller; wherein, K_iDenotes an integral coefficient, j denotes the number of samples, e (j) denotes an error value at the j-th sample, K_dDenotes a differential coefficient, and Δ e (k) denotes a first error difference.

The excitation controller control method and the excitation controller control system can automatically determine different excitation control laws according to the working state and the error condition of the excitation control system, namely preset control conditions, so that the control strategy is more flexible; the parameters of the excitation controller are automatically adjusted, so that the excitation controller has stronger adaptability, the characteristic of intelligent control is embodied, and the control effect of the excitation control system is better.

Fig. 3 is a structural diagram of a control system of an excitation controller according to an embodiment of the present invention. Referring to fig. 3, the excitation controller control system includes:

and a mathematical model obtaining module 201, configured to obtain a mathematical model of the excitation control system. The mathematical model of the controlled object in the excitation control system is as follows:

wherein G(s) represents a transfer function of a mathematical model of a controlled object in the excitation control system, K_ATo amplify the voltage ratio of the link, T_ATo amplify the time constant of the element, s denotes a complex field variable, K_GFor the amplification factor of the synchronous generator, T_GIs the time constant of the synchronous generator.

The parameter determination module 202 is used for determining parameters of a control strategy of the excitation controller by using a PID control and excitation control system mathematical model; the parameters include: proportional coefficient, integral coefficient, differential coefficient, integral time constant, differential time constant, sampling time, and upper limit value S of control quantity₁Lower limit value S of control amount₂A first predetermined error threshold L₁And a second predetermined error threshold L₂。

The difference determining module 203 is configured to determine a difference between an error value of the excitation control system at the k-th sampling and a first error value of the excitation control system at the k-1 th sampling as a first error difference, and determine a difference between the first error value and a second error value of the excitation control system at the k-2 th sampling as a second error difference; where k represents the number of samples.

The difference determining module 203 specifically includes:

and the error value acquisition unit is used for acquiring an error value of the excitation control system during sampling at the kth time, a first error value during sampling at the kth-1 time and a second error value during sampling at the kth-2 time.

A first error difference value determination unit, configured to determine a difference value between the error value at the time of the kth sampling and the first error value as a first error difference value, that is, Δ e (k) ═ e (k) — e (k-1), Δ e (k) denotes the first error difference value, e (k) denotes the error value at the time of the kth sampling, and e (k-1) denotes the first error value.

A second error difference value determination unit configured to determine a difference value between the first error value and the second error value as a second error difference value, i.e., [ delta ] e (k-1) ═ e (k-1) -e (k-2), where [ delta ] e (k-1) denotes the second error difference value, and [ e (k-2) denotes the second error value.

The preset control condition determining module 204 is configured to determine a preset control condition corresponding to the current state of the excitation controller by using the error value at the kth sampling, the first error difference value, and the second error difference value; the preset control conditions include: the control method comprises the following steps of first preset control conditions, second preset control conditions, third preset control conditions, fourth preset control conditions and fifth preset control conditions.

The preset control condition determining module 204 specifically includes:

the first judging unit is used for judging whether the absolute value of the error value in the k-th sampling is larger than a first preset error threshold value or not to obtain a first judging result.

And the first preset control condition determining unit is used for determining the preset control condition corresponding to the current state as the first preset control condition when the first judgment result is yes.

And the second judgment unit is used for judging whether the product of the error value and the first error difference value in the k-th sampling is larger than zero or whether the first error difference value is equal to zero or not when the first judgment result is negative, so as to obtain a second judgment result.

A second preset control condition determining unit, configured to determine that the preset control condition corresponding to the current state is the second preset control condition when the second determination result is yes, and the second determination result is e (k) △ e (k)>0 or △ e (k) 0, i.e. (1)

Or (2)Or (3) e (k) -e (k-1) ═ 0. For (1), it means that the error value at the k-th sampling is positive, and when increasing, the absolute value of the error value at the k-th sampling is increasing; for (2), it indicates that the error value at the k-th sampling is negative and continues to decrease, and the absolute value of the error value at the k-th sampling increases; the error is unchanged for (3).

And the third judging unit is used for judging whether the product of the error value in the k-th sampling and the first error difference value is smaller than zero and whether the product of the first error difference value and the second error difference value is larger than zero or whether the error value in the k-th sampling is equal to zero to obtain a third judging result if the second judging result is negative.

And the third preset control condition determining unit is used for determining that the preset control condition corresponding to the current state is the third preset control condition when the third judgment result is yes. The third determination result is e (k) Δ e (k) <0 and Δ e (k) > e (k-1) >0, or e (k) >0, i.e., (1) e (k-2) < e (k-1) < e (k) <0 or (2)0< e (k) < e (k-1) < e (k-2) or (3) r (k) -y (k) >0, where (1) and (2) mean that the absolute value of the error changes in a direction toward decrease, and (3) mean that the error has reached an equilibrium state.

And the fourth judging unit is used for judging whether the product of the error value and the first error difference value in the k-th sampling is smaller than zero or not and whether the product of the first error difference value and the second error difference value is smaller than zero or not when the third judging result is negative, so as to obtain a fourth judging result.

A fourth preset control condition determining unit, configured to, when the fourth determination result is yes, determine that the preset control condition corresponding to the current state is the fourth preset control condition, where the fourth determination result is yes, that is, e (k) △ e (k)<0 and △ e (k) △ e (k-1)<0, i.e. (1)0<e(k)<e(k-1)>e (k-2) or (2)(1) And (2) both mean that the error is in an extreme state.

And the fifth judging unit is used for judging whether the absolute value of the error value in the k sampling is smaller than the preset precision of the excitation control system error or not when the fourth judging result is negative, so as to obtain a fifth judging result.

And the fifth preset control condition determining unit is used for determining that the preset control condition corresponding to the current state is the fifth preset control condition when the fifth judgment result is yes. The fifth judgment result is that the error is | e (k) | <, which is the preset precision of the excitation control system error, and indicates that the error is very small, and an integral link can be added into the excitation controller to reduce the steady-state error.

And a control excitation controller output module 205, configured to control output of the excitation controller by using a control strategy corresponding to a preset control condition corresponding to the current state.

The excitation controller output control module 205 specifically includes:

and the open-loop control unit is used for determining the output of the excitation controller as a preset value and performing open-loop control on the excitation control system when the preset control condition corresponding to the current state is a first preset control condition.

And the sixth judging unit is used for judging whether the absolute value of the error value in the k-th sampling is greater than or equal to a second preset error threshold value or not when the preset control condition corresponding to the current state is a second preset control condition, so as to obtain a sixth judging result.

A first output unit for outputting a sixth judgment result according to the publicFormula u (K) ═ u (K-1) + K₁K_pe (k) determining the output of the excitation controller; wherein u (K) represents the output of the excitation controller, u (K-1) represents the output of the excitation controller at the time of sampling at the K-1 th time, and K₁Representing the amplification factor, K, of the excitation control system₁>1，K_pRepresents the scaling factor, and e (k) represents the error value at the k-th sampling. The sixth determination result is that the error is large because the error changes in a direction in which the absolute value of the error increases, and a strong control action needs to be performed by the excitation controller to quickly reduce the absolute value of the error.

A second output unit, configured to, when the sixth determination result is negative, obtain u (K) + K according to the formula u (K) ═ u (K-1) + K₂K_pe (k) determining the output of the excitation controller; wherein, K₂Representing the suppression factor, K, of the excitation control system₂<1. If the sixth determination result is no, the error is not so large although it changes in a direction in which the absolute value of the error increases.

And the maintaining output unit is used for maintaining the output of the excitation controller when the preset control condition corresponding to the current state is a third preset control condition. The output of the excitation controller may remain unchanged, i.e. u (k) ═ u (k).

And the seventh judging unit is used for judging whether the absolute value of the error value in the k-th sampling is greater than or equal to a second preset error threshold value or not when the preset control condition corresponding to the current state is a fourth preset control condition, so as to obtain a seventh judging result.

A third output unit, configured to, when the seventh determination result is yes, obtain u (K) + K according to the formula u (K) ═ u (K-1) + K₁K_pe (k-1) determining the output of the excitation controller; where e (k-1) represents a first error value. The seventh determination result is yes, which indicates that the absolute value of the error is large at this time, and the excitation controller can perform a strong control action.

A fourth output unit, configured to, when the seventh determination result is negative, obtain u (K) + K according to the formula u (K) ═ u (K-1) + K₂K_pe (k-1) determines the output of the excitation controller. If the seventh determination result is no, the absolute value of the error is small, and the excitation controller can perform a weak control action.

A fifth output unit, configured to, when the preset control condition corresponding to the current state is a fifth preset control condition, obtain the current state according to a formula

Determining an output of an excitation controller; wherein, K_iDenotes an integral coefficient, j denotes the number of samples, e (j) denotes an error value at the j-th sample, K_dDenotes a differential coefficient, and Δ e (k) denotes a first error difference.

The embodiment also provides a generator excitation controller control method based on expert PID, which comprises the following steps:

1. excitation control system mathematical model establishment

The excitation control system of this embodiment is a synchronous generator excitation control system, and before determining the control method of the excitation controller, the composition of each link of the synchronous generator excitation control system needs to be analyzed to obtain the transfer function of the synchronous generator excitation control system, so as to establish a mathematical model of the synchronous generator excitation control system.

The excitation control system includes: the device comprises an excitation controller, a power amplification unit, a synchronous generator and a voltage measurement unit. The output end of the excitation controller is connected with the input end of the power amplification unit, the output end of the power amplification unit is connected with the input end of the synchronous generator, the input end of the voltage measurement unit is connected with the output end of the synchronous generator, and the output end of the voltage measurement unit is connected with the input end of the excitation controller.

1.1 the transfer function of the power amplification unit is:

1.2 transfer function of synchronous generator is:

1.3 the transfer function of the voltage measurement unit is:

the mathematical model of the controlled object in the excitation control system of the synchronous generator is as follows:

in the above formula, G₁(s) represents the transfer function of the power amplification unit, s represents a complex field variable, K_ATo amplify the voltage ratio of the link, T_ATo amplify the time constant of the element, G₂(s) represents the transfer function of the synchronous generator, K_GFor generator amplification factor, T_GAs generator time constant, G₃(s) represents the transfer function of the voltage measuring cell, K₃Is a voltage proportionality coefficient, T₃For measuring the loop time constant, G(s) represents the transfer function of the mathematical model of the controlled object in the excitation control system.

2. Expert PID-based control method for generator excitation controller

Before determining the control method of the generator excitation controller based on the expert PID, the control of the conventional PID controller is carried out on an excitation control system to obtain related parameters during the conventional PID control, so that related basis is provided for determining the control method of the expert PID controller.

The method comprises the following steps: obtaining related parameters through conventional PID control, wherein the related parameters comprise: coefficient of proportionality K_pIntegral coefficient K_iDifferential coefficient K_dIntegral time constant T_iDifferential time constant T_dSampling time T, upper limit value S of control quantity₁Lower limit value S of control amount₂A first predetermined error threshold L₁And a second predetermined error threshold L₂。

According to the PID control algorithm of a conventional PID controller, i.e.Wherein

u' (k) represents an output of the excitation controller when the PID control method is adopted; k_pIs a proportionality coefficient; e (k) represents an error value at the k-th sampling; k_iIs an integral coefficient; j and k both represent sampling times, j represents j sampling time, k represents k sampling time, and j is more than or equal to 0 and less than or equal to k; e (j) represents an error value of the excitation control system at the j sampling time; k_dIs a differential coefficient; Δ e (k) represents an error difference value between an error value at the k-th sampling time and an error value at the k-1-th sampling time of the excitation control system; t is sampling time; t is_iIs an integration time constant; t is_dIs the differential time constant.

After the PID controller is added into the excitation control system, a step signal is applied to the input end of the excitation control system, the change curve of the controlled variable is obtained through the response of the excitation control system, and then the upper limit value S of the controlled variable is determined through the change curve of the controlled variable₁And a lower limit value S₂To achieve saturation processing of the control quantity; namely, the upper limit value and the lower limit value of the controlled variable can be determined by observing the change range and the corresponding duration of the controlled variable according to the change curve of the controlled variable and combining the response curve of a simulation experiment observation system, and if the process is not carried out, the upper limit value and the lower limit value of the controlled variable cannot be known.

After the PID controller is added into the excitation control system, a step signal is applied to the input end of the excitation control system, the change curve of the error is obtained through the response of the excitation control system, and then the first preset error threshold value L is determined₁And a second predetermined error threshold L₂. The error is an error e (k) of the excitation control system, which is a deviation between a system input r (k) and a system output y (k) of the excitation control system, i.e., e (k) r (k) -y (k). The corresponding error range can be determined by using the variation curve of the error, in this embodiment, the maximum value of the error is 1, and L is₁Taking the error as 80 percent of the maximum value, namely 0.8; l is₂Taking the error as 5 percent of the maximum value, namely 0.05; l is₁Is a large error threshold, i.e. when the error is greater than L₁When the error is large, the error is considered to be large; l is₂Is a larger error threshold, i.e. when the error is larger than L₂The error is considered to be large. The output response curve of the excitation control system, the change curve of the control quantity, the change curve of the error and the like can be observed by an oscilloscope.

Step two: and determining an expert PID control condition. Let e (k) denote the error value at the k-th sampling of the discretization, e (k-1) denotes the error value at the k-1-th sampling (i.e. the first error value), e (k-2) denotes the error value at the k-2-th sampling (i.e. the second error value), then: Δ e (k) ═ e (k) — e (k-1), Δ e (k-1) ═ e (k-1) -e (k-2), Δ e (k-1) denotes a second error value, and e (k-2) denotes a second error value.

Condition 1: if | e (k) laces>L₁The first step is to output the control quantity in a fixed value by combining the variation curve of the error in the first step and the degree of the error, and to perform open loop control on the excitation control system. In the present embodiment, when the error is greater than 80%, 60%, 40%, 20% or 1% of the maximum value, the constant value output by the control amount is 100,80,40,10 or 0.1, respectively, and the open-loop control is performed on the excitation control system. When the error exceeds 80% of the maximum error value, the control amount is controlled by the upper limit value S of the control amount₁It is given. Can be paired with L₁Further refined into a plurality of points for respective open-loop control, i.e. L₁Subdivided into a plurality of points, e.g. in this embodiment, L₁The control quantity is subdivided into 5 points, which are respectively 80%, 60%, 40%, 20% or 1% of the maximum value of the error, namely when the error is more than 80%, 60%, 40%, 20% or 1% of the maximum value, the control quantity respectively corresponds to the fixed value (the upper limit value S of the control quantity) output₁) Comprises the following steps: 100,80,40,10 or 0.1, to achieve the effect of rapidly reducing the excitation control system error. According to the actual control requirement, L is adjusted₁The excitation controller is thinned into a plurality of points, the control effect of the excitation controller is better, and if the control effect is not very high, the excitation controller does not need to be thinned into a plurality of points or the thinned points are reduced.

Condition 2 if e (k) △ e (k)>0 or △ e (k) 0, i.e. (1)Or (2)

Or (3) e (k) -e (k-1) ═ 0. For (1), it indicates that the error at the k-th sampling is positive, and the absolute value of the error is increasing; for (2), it indicates that the error at the k-th sampling is negative and continues to decrease, and the absolute value of the error is increasing; the error is unchanged for (3).

And if | e (k) | ≧ L₂When the error is described to be large and the error is changed in a direction in which the absolute value of the error increases, the excitation controller needs to generate a strong control action to rapidly decrease the absolute value of the error, and the output of the excitation controller is: u (K) ═ u (K-1) + K₁K_pe(k)；K₁>1 is the amplification factor.

If | e (k) laces<L₂Although the error changes in the direction of increasing the absolute value of the error, the error is not very large, and the output of the excitation controller is: u (K) ═ u (K-1) + K₂K_pe(k)；K₂<1 is an inhibition factor.

Condition 3: if e (k) Δ e (k) <0 and Δ e (k) >0, or e (k) >0, i.e., (1) e (k-2) < e (k-1) < e (k) <0 or (2)0< e (k) < e (k-1) < e (k-2) or (3) r (k) -y (k) >0, where (1) and (2) mean that the absolute value of the error changes in a direction toward decrease and (3) mean that the error has reached an equilibrium state. The output of the excitation controller may remain unchanged at this time, i.e., u (k).

Condition 4 if e (k) △ e (k)<0 and △ e (k) △ e (k-1)<At 0 time, i.e. (1)0<e(k)<e(k-1)>e (k-2) or (2)(1) And (2) both mean that the error is in an extreme state.

And if | e (k) | ≧ L₂In this case, the absolute value of the error is large, the excitation controller can perform a strong control action, and the output of the excitation controller is: u (K) ═ u (K-1) + K₁K_pe(k-1)。

And if | e (k) does not count<L₂The absolute value of the explanation error is small, the excitation controller can implement a weak control action, and the output of the excitation controller is as follows: u (K) ═ u (K-1) + K₂K_pe(k-1)。

Condition 5: when | e (k) laces<In the process, for the preset precision of the excitation control system error, the error is very small, and an integral link can be added into an excitation controller to reduce the steady-state error. At this time, the output of the excitation controller after the integration link is added is as follows:

in order to embody the control effect of the generator excitation controller control method of the present invention, three control methods, namely, a simple negative feedback closed-loop control method, a conventional PID control method and a generator excitation controller control method of the present invention, are respectively applied to an excitation control system, output response curves, error change curves and control quantity change curves of a synchronous generator excitation control system corresponding to the three control methods are respectively shown in fig. 4, 5 and 6, and the horizontal axes of fig. 4, 5 and 6 are response time of the excitation control system, unit: second(s); in fig. 4, the system input represents the system input r of the excitation control system, the conventional PID control represents the system output y of the excitation control system implementing the conventional PID control method, the expert PID control represents the system output y of the excitation control system implementing the generator excitation controller control method of the present invention, and the simple negative feedback closed-loop control represents the system output y of the excitation control system implementing the simple negative feedback closed-loop control method. From fig. 5 and 6, the variation of two parameters of the error and the control quantity under three control methods can be seen; as is apparent from fig. 4, when the excitation control system adopts the generator excitation controller control method of the present invention, the dynamic performance indexes such as overshoot and adjustment time of the excitation control system are significantly better than those of the other two control methods, and the output responses of the three control methods are respectively compared with the system input, so that the output of the generator excitation controller control method of the present invention is closer to the system input than the other two control methods, and the control effect of the excitation control system is better.

The embodiment also provides a specific application example of the excitation controller control method: taking a synchronous generator excitation control system as an example, a control method of a generator excitation controller is determined.

Establishing a mathematical model of an excitation control system: specific parameters of the excitation control system of the synchronous generator are shown in table 1:

TABLE 1 specific parameters of a synchronous generator excitation control system

The corresponding controlled object mathematical model can be obtained as follows:

wherein G(s) represents a transfer function of a mathematical model of a controlled object in the excitation control system of the synchronous generator, and s represents a variable of a complex number field.

The control method of the generator excitation controller comprises the following steps: the relevant parameters are obtained by conventional PID control.

The excitation control system of the synchronous generator uses a conventional PID controller, and after relevant parameters are adjusted, corresponding K can be obtained when conventional PID control is obtained_p、K_i、K_d、T_i、T_dAnd T is 60, 40, 25, 0.0015 seconds, 0.00042 seconds, and 0.001 seconds, respectively. Obtaining a change curve of the controlled variable through step response of a synchronous generator excitation control system, and determining an upper limit value S of the controlled variable₁100 and lower limit S₂-100. Obtaining a variation curve of an error through the response of a synchronous generator excitation control system, and further determining a first preset error threshold value L₁And a second predetermined error threshold L₂In the present application example, L is₁Subdivided into 5 points, 0.8, 0.6, 0.4, 0.2 and 0.01, respectively, with a maximum of 0.8 and a minimum of 0.01, specifically denoted as L₁₀＝0.8、L₁₁＝0.6、L₁₂＝0.4、L₁₃0.2 and L₁₄＝0.01，L₂＝0.05。

Condition 1: when | e (k) laces>L₁₀When 0.8, u (k) is S₁100. When | e (k) laces>L₁₁When 0.6, u (k) is 80. When | e (k) laces>L₁₂When 0.4, u (k) is 40. When | e (k) laces>L₁₃When 0.2, u (k) is 10. When | e (k) laces>L₁₄When 0.01, u (k) is 0.1. In the present condition 1, the control amounts outputted from the excitation controller are all based on L₁The specific value of the synchronous generator is output in different constant value modes, and open loop control is carried out on a synchronous generator excitation control system to rapidly reduce errors.

Condition 2: when e (k) Δ e (k) >0 or Δ e (k) is 0,

if | e (K) | ≧ 0.05, the output of the controller is u (K) ═ u (K-1) +1.5 × 60e (K), K₁＝1.5；

If | e (k) laces<0.05, the output of the controller is u (K) ═ u (K-1) +0.4 × 60e (K), K₂＝0.4。

Condition 3: when e (k) Δ e (k) <0 and Δ e (k) Δ e (k-1) >0, or when e (k) ═ 0, the output of the excitation controller at this time may remain unchanged, i.e., u (k) ═ u (k).

Condition 4: when e (k) Δ e (k) <0 and Δ e (k) Δ e (k-1) <0,

if | e (k) | ≧ 0.05, which indicates that the absolute value of the error is large, the excitation controller can implement a strong control action, and u (k) ═ u (k-1) +1.5 × 60e (k-1);

if | e (k) | <0.05, which indicates that the absolute value of the error is small, the excitation controller may perform a weak control action, and u (k) ═ u (k-1) +0.4 × 60e (k-1).

Condition 5: when | e (k) | < ═ 0.001, the output of the excitation controller at this time is:

the embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.