阅读说明：本技术 基于电流控制的热网首站异步发电机组有功功率控制方法 (Active power control method of heat supply network head station asynchronous generator set based on current control ) 是由 郭江龙 米大斌 刘书安 李琼 张颖 马涛 王涛 张立 周明君 刘波 刘秋升 李 于 2020-06-01 设计创作，主要内容包括：本发明公开了一种基于电流控制的热网首站异步发电机组有功功率控制方法,具体包括：选取异步发电机A、B、C三相电流进入模拟量筛选模块,选取合适电流信号作为控制系统的实测电流信号值；实时测量异步发电机定子线圈温度值；将电流基准值与异步发电机的定子线圈温度值、实测电流信号值送入PID控制器进行比例积分运算；PID控制器调节运算的结果,通过手自动模拟量控制器T1、切换模块T2,以及速率限制模块V控制汽轮机进汽调节阀进行进气量的调节。本发明通过以发电机电流为控制对象,解决了并网母线电压波动时异步发电机过电流运行以及蒸汽母管压力快速变化导致机组过负荷的现象,实现了异步汽轮发电机组安全稳定运行。(The invention discloses a current control-based active power control method for an asynchronous generator set at a heat supply network head station, which specifically comprises the following steps: selecting three-phase current of the asynchronous generator A, B, C to enter an analog quantity screening module, and selecting a proper current signal as an actually measured current signal value of the control system; measuring the temperature value of the stator coil of the asynchronous generator in real time; sending the current reference value, the stator coil temperature value of the asynchronous generator and the actually measured current signal value into a PID controller for proportional integral operation; and the PID controller adjusts the operation result, and controls the steam inlet adjusting valve of the steam turbine to adjust the air inlet amount through the manual and automatic analog quantity controller T1, the switching module T2 and the speed limiting module V. According to the invention, the generator current is taken as a control object, so that the phenomena of overload of the asynchronous generator caused by overcurrent operation of the asynchronous generator and rapid pressure change of a steam main pipe when the voltage of a grid-connected bus fluctuates are solved, and the safe and stable operation of the asynchronous steam turbine generator unit is realized.)

1. A heat supply network head station asynchronous generator set active power control method based on current control is characterized in that the control method controls the active power of an asynchronous generator set based on measured current, and specifically comprises the following steps:

A. selecting three-phase current of the asynchronous generator A, B, C to enter an analog quantity screening module, and selecting a proper current signal as an actually measured current signal value of the control system; measuring the temperature value of the stator coil of the asynchronous generator in real time;

B. sending the current reference value, the stator coil temperature value of the asynchronous generator and the actually measured current signal value into a PID controller for proportional integral operation; and the PID controller adjusts the operation result, and controls the steam inlet adjusting valve of the steam turbine to adjust the air inlet amount through the manual and automatic analog quantity controller T1, the switching module T2 and the speed limiting module V.

2. The active power control method of the heat supply network head station asynchronous generator set based on the current control as claimed in claim 1, wherein the selection method of the asynchronous generator current signal in the step a is as follows: the three current signals are good and have small deviation, and the median of the three current signals is taken; if one current signal is poor, taking the average value of the other two good current signals; two current signals are poor, and the other current signal is good.

3. The method for controlling the active power of the asynchronous generator set at the head station of the heat supply network based on the current control as claimed in claim 1, wherein the operation method of the PID controller in the step B is as follows:

B1. firstly, comparing an actually measured current signal value of an asynchronous generator with a current reference value, and when the deviation between the actually measured current signal value and the current reference value is larger than H1, outputting an output signal to an OR gate OR 1; simultaneously inputting a turbine trip signal to an OR gate OR 1; an output signal of the OR gate 1 is connected to a MASTATION switch manual MRE input end, and the power control of the generator is switched to a manual state;

B2. when the deviation between the actually measured current signal value and the current reference value is smaller than H1, the actually measured current signal value of the asynchronous generator is subjected to high-low limit judgment; when the actually measured current signal value is larger than the set value of H4, the output signal passes through a pulse rising delayer TD _ ON2 and then is input into an OR gate OR 2; when the actually measured current signal value is smaller than H4 and larger than the set value of H3, the output signal passes through a pulse rising delayer TD _ ON1 and then is input into an OR gate OR 2; the method comprises the steps that high and low limit judgment is carried out ON the temperature value of a stator coil of an asynchronous generator wire, when the temperature value of the stator coil is larger than a set value H6, an output signal is input into an OR gate OR2 after passing through a pulse rising delayer TD _ ON 3; an output signal of an OR gate OR2 AND a grid-connected signal of an asynchronous generator are jointly input into an AND gate AND1 module, an output signal of an AND gate AND1 module is connected to a set end of an RS trigger, an output signal of the RS trigger is respectively connected to an OR gate OR1, a switching module T2 AND a speed limiting module V, a switching manual MRE input end of a MASTATION is connected through an OR gate OR1, the power control of the generator is switched to a manual state, AND meanwhile, a steam turbine steam inlet regulating valve is controlled to be reduced to a preset safety value A1 according to a speed A2 set by the speed limiting module V through a switching module T2 AND the speed limiting module V;

B3. when the measured current signal value is smaller than H3 and larger than the set value of H2, outputting a signal to an OR gate OR 3; the method comprises the steps that high and low limit judgment is carried out on the temperature value of a stator coil of an asynchronous generator wire, and when the temperature value of the stator coil is smaller than H6 and larger than a set value of H5, a signal is output to an OR gate OR 3; the output signal of OR3 is connected to the locking RAI interface of the MASTATION, the output signal of the MASTATION is connected to the manual and automatic analog quantity controller T1, and the steam inlet valve of the steam turbine is controlled to be locked;

B4. when the measured current signal value is smaller than the set value of L1, outputting a signal to an AND gate AND 2; when the stator coil temperature of the asynchronous generator is less than the set value of L2, inputting a signal to an AND gate AND 2; the output signal of the AND2 is connected to the reset end of the RS trigger, the RS trigger resets, AND the steam turbine steam inlet regulating valve is controlled to be switched to a normal state through the switching module T2.

4. The method for current control-based active power control of the heat supply network head station asynchronous generator set according to claim 3, wherein the delay duration of the pulse rise delay device TD _ ON2 is shorter than the delay duration of the pulse rise delay device TD _ ON 1.

Technical Field

The invention relates to the technical field of thermal power generation energy-saving utilization and thermal control, in particular to a method for controlling active power of an asynchronous generator set at a heat supply network head station.

Background

Thermal power generation is one of the biggest coal consumption users in China as the most main power generation form in the electric power structure in China, and a heat supply power plant becomes one of the biggest industries for saving energy and reducing consumption along with the continuous formation of the situation that a large-capacity and high-parameter coal-fired power generating set in China is the main heat supply body for cities. In order to fully utilize the pressure loss of heat supply extraction steam, a backpressure steam turbine is adopted to drive an asynchronous generator to generate electricity, namely, steam firstly drives the asynchronous generator to do work through the backpressure steam turbine, the low-pressure exhaust steam of a backpressure machine is utilized to meet the requirement of heat load of a user, the low-level heat energy can be reasonably utilized in a gradient mode, and the comprehensive utilization efficiency of the heat supply steam is improved.

The load control of a synchronous generator and a turbonator system is adopted in a large-scale thermal power plant, the active power of the generator is used as a control object in a conventional mode, and a closed-loop control system is adopted to realize the stable control of unit load. In view of investment, operation and maintenance cost, asynchronous generators are also widely used in small generators. When the plant generator operates in an in-phase mode according to the scheduling requirement, the voltage of the generator outlet machine terminal is reduced, the voltage of the 6kV service bus taken from the generator outlet is reduced, the bus voltage is reduced to 5.9kV from the rated 6.3kV at most, and the voltage of the asynchronous generator connected to the 6kV service bus can fluctuate along with the voltage change of the generator machine terminal of the plant. When the asynchronous generator runs at full load, if the load is maintained unchanged, the bus wire is lowered, the current of the generator is inevitably increased, so that the overcurrent of the generator when the asynchronous generator runs at the full load state, the temperature of a coil is increased, insulation aging is caused, and the safe running and the service life of equipment are influenced. Meanwhile, as the two asynchronous generator sets run in parallel through the main pipe, when one of the two asynchronous generator sets trips due to failure, the pressure of the steam main pipe can rise rapidly, and the asynchronous generator set which normally runs is overloaded due to lag adjustment, or even the asynchronous generator is damaged due to overlarge current.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for controlling the active power of an asynchronous generator unit at a first heat supply network station based on current control, and the method is used for solving the phenomenon of unit overload caused by the over-current operation of an asynchronous generator and the rapid pressure change of a steam main pipe when the voltage of a grid-connected bus fluctuates by taking the current of the generator as a control object, so as to realize the safe and stable operation of the asynchronous steam turbine generator unit.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows.

A heat supply network head station asynchronous generator set active power control method based on current control is used for controlling the active power of an asynchronous generator set based on measured current and specifically comprises the following steps:

A. selecting three-phase current of the asynchronous generator A, B, C to enter an analog quantity screening module, and selecting a proper current signal as an actually measured current signal value of the control system; measuring the temperature value of the stator coil of the asynchronous generator in real time;

B. sending the current reference value, the stator coil temperature value of the asynchronous generator and the actually measured current signal value into a PID controller for proportional integral operation; and the PID controller adjusts the operation result, and controls the steam inlet adjusting valve of the steam turbine to adjust the air inlet amount through the manual and automatic analog quantity controller T1, the switching module T2 and the speed limiting module V.

In the method for controlling the active power of the asynchronous generator set at the head station of the heat supply network based on current control, the method for selecting the current signal of the asynchronous generator in the step A comprises the following steps: the three current signals are good and have small deviation, and the median of the three current signals is taken; if one current signal is poor, taking the average value of the other two good current signals; two current signals are poor, and the other current signal is good.

In the method for controlling the active power of the asynchronous generator set at the head station of the heat supply network based on current control, the operation method of the PID controller in the step B is as follows:

B1. firstly, comparing an actually measured current signal value of an asynchronous generator with a current reference value, and when the deviation between the actually measured current signal value and the current reference value is larger than H1, outputting an output signal to an OR gate OR 1; simultaneously inputting a turbine trip signal to an OR gate OR 1; an output signal of the OR gate 1 is connected to a MASTATION switch manual MRE input end, and the power control of the generator is switched to a manual state;

B2. when the deviation between the actually measured current signal value and the current reference value is smaller than H1, the actually measured current signal value of the asynchronous generator is subjected to high-low limit judgment; when the actually measured current signal value is larger than the set value of H4, the output signal passes through a pulse rising delayer TD _ ON2 and then is input into an OR gate OR 2; when the actually measured current signal value is smaller than H4 and larger than the set value of H3, the output signal passes through a pulse rising delayer TD _ ON1 and then is input into an OR gate OR 2; the method comprises the steps that high and low limit judgment is carried out ON the temperature value of a stator coil of an asynchronous generator wire, when the temperature value of the stator coil is larger than a set value H6, an output signal is input into an OR gate OR2 after passing through a pulse rising delayer TD _ ON 3; an output signal of an OR gate OR2 AND a grid-connected signal of an asynchronous generator are jointly input into an AND gate AND1 module, an output signal of an AND gate AND1 module is connected to a set end of an RS trigger, an output signal of the RS trigger is respectively connected to an OR gate OR1, a switching module T2 AND a speed limiting module V, a switching manual MRE input end of a MASTATION is connected through an OR gate OR1, the power control of the generator is switched to a manual state, AND meanwhile, a steam turbine steam inlet regulating valve is controlled to be reduced to a preset safety value A1 according to a speed A2 set by the speed limiting module V through a switching module T2 AND the speed limiting module V;

B3. when the measured current signal value is smaller than H3 and larger than the set value of H2, outputting a signal to an OR gate OR 3; the method comprises the steps that high and low limit judgment is carried out on the temperature value of a stator coil of an asynchronous generator wire, and when the temperature value of the stator coil is smaller than H6 and larger than a set value of H5, a signal is output to an OR gate OR 3; the output signal of OR3 is connected to the locking RAI interface of the MASTATION, the output signal of the MASTATION is connected to the manual and automatic analog quantity controller T1, and the steam inlet valve of the steam turbine is controlled to be locked;

B4. when the measured current signal value is smaller than the set value of L1, outputting a signal to an AND gate AND 2; when the stator coil temperature of the asynchronous generator is less than the set value of L2, inputting a signal to an AND gate AND 2; the output signal of the AND2 is connected to the reset end of the RS trigger, the RS trigger resets, AND the steam turbine steam inlet regulating valve is controlled to be switched to a normal state through the switching module T2.

In the active power control method of the heat supply network head station asynchronous generator set based ON current control, the delay time of the pulse rising delayer TD _ ON2 is shorter than the delay time of the pulse rising delayer TD _ ON 1.

Due to the adoption of the technical scheme, the technical progress of the invention is as follows.

According to the invention, the current of the asynchronous generator is taken as a control object, and the regulating valve of the steam turbine is locked to be continuously opened when the current of the asynchronous generator and the temperature of the stator coil of the generator reach set alarm values by judging the current of the asynchronous generator; when the current of the asynchronous generator and the temperature of the stator coil of the generator reach preset action values, the regulating valve of the steam turbine can be turned down to a safe position at a set speed, the phenomenon that the overload of the generator is caused by the overcurrent of the asynchronous generator and the rapid pressure change of the steam main pipe when the voltage of the grid-connected bus fluctuates is solved, the problems of the overtemperature, insulation aging and the like of the stator coil of the asynchronous generator are avoided, and the safe and stable operation of the asynchronous generator set is reliably guaranteed.

Drawings

FIG. 1 is a schematic diagram of an asynchronous generator set in an embodiment;

FIG. 2 is a schematic diagram of an active power control strategy for a conventional power plant steam turbine generator set;

FIG. 3 is a schematic diagram of an active power control strategy of an asynchronous generator set at a head station of a heat supply network based on current control in an embodiment;

wherein: 1. the system comprises a first back pressure turbine, a second back pressure turbine, a third asynchronous generator, a fourth asynchronous generator, a fifth asynchronous generator, a sixth.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

In the embodiment, the simple diagram of the asynchronous generator set is shown in figure 1 and comprises a first asynchronous generator 1 and a second asynchronous generator 4 which are arranged in parallel, the two asynchronous generators are respectively connected with a heat supply and air exhaust output end through a back pressure turbine and a turbine steam inlet regulating valve, and the output ends of the two asynchronous generators are respectively connected to A, B sections of 6kV station power. In the process of active power control of the asynchronous generator sets, each generator set respectively independently controls the steam inlet regulating valve of the steam turbine to ensure the safe and stable operation of the corresponding asynchronous generator sets.

The control method of the present invention has a flow chart as shown in fig. 3, and specifically includes the following steps.

A. Selecting three-phase current of the asynchronous generator A, B, C to enter an analog quantity screening module, and selecting a proper current signal as an actually measured current signal value of the control system; and measuring the temperature value of the stator coil of the asynchronous generator in real time.

The selection method of the current signal of the asynchronous generator comprises the following steps: the three current signals are good and have small deviation, and the median of the three current signals is taken; if one current signal is poor, taking the average value of the other two good current signals; two current signals are poor, and the other current signal is good.

B. Sending the current reference value, the stator coil temperature value of the asynchronous generator and the actually measured current signal value into a PID controller for proportional integral operation; and the PID controller adjusts the operation result, and controls the steam inlet adjusting valve of the steam turbine to adjust the air inlet amount through the manual and automatic analog quantity controller T1, the switching module T2 and the speed limiting module V.

In this step, the operation method of the PID controller and the control method of the steam inlet regulating valve of the steam turbine are as follows.

B1. Firstly, comparing an actually measured current signal value of an asynchronous generator with a current reference value, and when the deviation between the actually measured current signal value and the current reference value is larger than H1, outputting an output signal to an OR gate OR 1; simultaneously inputting a turbine trip signal to an OR gate OR 1; an output signal of the OR gate 1 is connected to a MASTATION switch manual MRE input end, and the power control of the generator is switched to a manual state.

In this embodiment, the setting value of H1 is 50A, that is, when the deviation between the measured current signal value and the current reference value is greater than 50A, the power control of the generator is switched to the manual state immediately, so as to avoid further deterioration of the operating condition; or when the plant control system signals a turbine trip, the generator power control is also switched to a manual state.

B2. And when the deviation between the actually measured current signal value and the current reference value is smaller than H1, judging the actually measured current signal value of the asynchronous generator to be high or low. When the actually measured current signal value is larger than the set value of H4, the output signal passes through a pulse rising delayer TD _ ON2 and then is input into an OR gate OR 2; when the actually measured current signal value is smaller than H4 and larger than the set value of H3, the output signal passes through a pulse rising delayer TD _ ON1 and then is input into an OR gate OR 2; the method comprises the steps that high and low limit judgment is carried out ON the temperature value of a stator coil of an asynchronous generator wire, when the temperature value of the stator coil is larger than a set value H6, an output signal is input into an OR gate OR2 after passing through a pulse rising delayer TD _ ON 3; an output signal of the OR gate OR2 AND a grid-connected signal of the asynchronous generator are jointly input into an AND gate AND1 module, an output signal of an AND gate AND1 module is connected to a set end of an RS trigger, an output signal of the RS trigger is respectively connected to an OR gate OR1, a switching module T2 AND a speed limiting module V, a switching manual MRE input end of a MASTATION is connected through an OR gate OR1, power control of the generator is switched to a manual state, AND meanwhile, a steam turbine steam inlet regulating valve is controlled to be reduced to a preset safety value A1 according to a speed A2 set by the speed limiting module V through a switching module T2 AND the speed limiting module V.

In the present invention, since the H4 setting is greater than the H3 setting, the delay period of the pulse-up delay TD _ ON2 is less than the delay period of the pulse-up delay TD _ ON 1.

In this embodiment, the setting value of H4 is 700A, and the delay time of the pulse rising delayer TD _ ON2 is 3 s; h3 has a setting value of 680A, and the delay time of the pulse rise delayer TD _ ON1 is 120 s; h6, setting value at 130 ℃, and delay time of the pulse rising delayer TD _ ON3 is 3 s; the preset safety value is 30%.

That is, when the measured current signal value is greater than 700A and the generator is in a grid-connected state, after delaying for 3s, the power control of the generator is switched to a manual state, and meanwhile, the switching module T2 and the rate limiting module V control the steam turbine steam inlet regulating valve to be reduced to a preset safety value a1 according to the rate a2 set by the rate limiting module V. Or when the measured current signal value is larger than 680A and the generator is in a grid-connected state, delaying for 120s, switching the power control of the generator to a manual state, and simultaneously controlling the steam turbine steam inlet regulating valve to be reduced to a preset safety value A1 according to the speed A2 set by the speed limiting module V through the switching module T2 and the speed limiting module V. Or when the temperature value of the stator coil is larger than 130 ℃ and the generator is in a grid-connected state, delaying for 3s, switching the power control of the generator to a manual state, and simultaneously controlling the steam turbine steam inlet regulating valve to be reduced to a preset safety value A1 according to the speed A2 set by the speed limiting module V through the switching module T2 and the speed limiting module V.

B3. When the measured current signal value is smaller than H3 and larger than the set value of H2, outputting a signal to an OR gate OR 3; the method comprises the steps that high and low limit judgment is carried out on the temperature value of a stator coil of an asynchronous generator wire, and when the temperature value of the stator coil is smaller than H6 and larger than a set value of H5, a signal is output to an OR gate OR 3; the output signal of OR3 is connected to the blocking and RAI increasing interface of the mask, the output signal of the mask is connected to the manual and automatic analog controller T1, and the steam inlet valve of the steam turbine is controlled to be blocked.

In this example, the H2 setting is 650A and the H5 setting is 110 ℃. Namely, when the measured current signal value is smaller than 680A and larger than 650A, or when the stator coil temperature value is smaller than 130 ℃ and larger than 110 ℃, the steam inlet valve of the steam turbine is controlled to be locked.

B4. When the measured current signal value is smaller than the set value of L1, outputting a signal to an AND gate AND 2; when the stator coil temperature of the asynchronous generator is less than the set value of L2, inputting a signal to an AND gate AND 2; the output signal of the AND2 is connected to the reset end of the RS trigger, the RS trigger resets, AND the steam turbine steam inlet regulating valve is controlled to be switched to a normal state through the switching module T2.

In the invention, the set value of L1 is less than or equal to the set value of H2, and the set value of L2 is less than or equal to the set value of H5. That is, when the measured current signal value is smaller than the set value of L1 or when the stator coil temperature of the asynchronous generator is smaller than the set value of L2, it is indicated that the asynchronous generator works normally, the RS trigger is reset, and the steam turbine steam inlet regulating valve is controlled to be switched to the normal state to operate.