阅读说明：本技术 一种计及饱和特性的发电机实用参数辨识模型及其辨识方法 (Generator practical parameter identification model considering saturation characteristic and identification method thereof ) 是由 张伟骏 刘智煖 蔡冰君 黄霆 方日升 张永树 林芳 苏清梅 张慧瑜 陈伯建 王文 于 2019-07-25 设计创作，主要内容包括：本发明涉及一种计及饱和特性的发电机实用参数辨识模型及其辨识方法,首先,运用Laplace变换,把发电机六阶实用时域模型方程组转换为频域模型方程组,对频域方程组进行代数变换,消去不可观测量e′<Sub>q</Sub>,e″<Sub>q</Sub>,e′<Sub>q0</Sub>,e″<Sub>q0</Sub>,e′<Sub>d</Sub>,e″<Sub>d</Sub>,e′<Sub>d0</Sub>,e″<Sub>d0</Sub>。然后对其作Laplace反变换,转换为以积分形式表示的消去不可观测量的计及饱和特性的实用参数辨识模型。接着对积分形式的参数辨识模型离散化,构造以dq轴电流计算值与实测值差值最小为目标的优化函数。在此基础上,建立了适用于PMU量测数据的发电机参数辨识策略,从而有效提高发电机参数辨识的精度。(The invention relates to a generator practical parameter identification model considering saturation characteristics and an identification method thereof. q ,e″ q ,e′ q0 ,e″ q0 ,e′ d ,e″ d ,e′ d0 ,e″ d0 . And then, performing Laplace inverse transformation on the model to convert the model into a practical parameter identification model which is represented in an integral form, eliminates unobservable quantity and takes saturation characteristics into account. And then discretizing the parameter identification model in an integral form, and constructing an optimization function taking the minimum difference value between the calculated value and the measured value of the dq-axis current as a target. On the basis, the PMU measurement data suitable for PMU measurement are establishedThe generator parameter identification strategy is adopted, so that the accuracy of generator parameter identification is effectively improved.)

1. A generator practical parameter identification model considering saturation characteristics is characterized in that: the method specifically comprises the following steps:

in the formula, X_q,X′_q,X″_q,T′_q0,T″_q0Quadrature-axis synchronous reactance, quadrature-axis transient and sub-transient open-circuit time constants, respectively; x_d,X′_d,X″_d,T′_d0,T″_d0Respectively time constants of a direct-axis synchronous reactance, a direct-axis transient reactance, a sub-transient reactance, a direct-axis transient and a sub-transient open circuit; said X_q,X′_q,X″_q,T′_q0,T″_q0And said X_d,X′_d,X″_d,T′_d0,T″_d0Are all identification parameters; x_lIs stator leakage reactance; i.e. i_d,i_qThe components of the generator terminal current in the d axis and the q axis are respectively; e.g. of the type_fInduced electromotive force is excited; order to

2. The method for establishing a generator practical parameter identification model considering saturation characteristics according to claim 1, wherein: the method comprises the following steps:

step S1: converting a six-order practical time domain model equation set of the generator into a frequency domain model equation set by using Laplace transformation, carrying out algebraic transformation on the frequency domain equation set, and eliminating an unobservable quantity e'_q,e″_q,e′_q0,e″_q0,e′_d,e″_d,e′_d0,e″_d0；

Step S2: and (4) performing Laplace inverse transformation on the equation set obtained by eliminating the unobservable quantity in the step S1, and converting the equation set into a generator practical parameter identification model which is expressed in an integral form, eliminates the unobservable quantity and takes saturation characteristics into account.

3. The method of claim 2, wherein the generator utility parameter identification model is based on saturation characteristics, and comprises: the step S1 specifically includes the following steps:

ignoring electromagnetic transients and armature resistance R of the stator winding_a(ii) a Transient processes of an excitation winding f, a rotor d and a rotor q shaft and saturation characteristics of a generator are calculated; the six-order practical model of the synchronous generator considering the influence of the saturation characteristic is as follows:

in the formula, X_q,X′_q,X″_q,T′_q0,T″_q0Quadrature-axis synchronous reactance, quadrature-axis transient and sub-transient open-circuit time constants, respectively; x_d,X′_d,X″_d,T′_d0,T″_d0Respectively a direct-axis synchronous reactance, a direct-axis transient state and a secondary transient stateA dynamic reactance, a direct axis transient, and a sub-transient open circuit time constant; said X_q,X′_q,X″_q,T′_q0,T″_q0And said X_d,X′_d,X″_d,T′_d0,T″_d0Are all identification parameters; x_lIs stator leakage reactance; u. of_d,i_d,u_q,i_qThe components of the voltage and the current at the generator terminal on the d axis and the q axis are respectively; e.g. of the type_fInduced electromotive force is excited; e'_q,e″_q,e′_d,e″_dThe electromotive forces are respectively alternating-current, direct-axis transient and sub-transient of the generator and are state variables; s_d,S_qD-axis and q-axis saturation factors respectively; delta, omega, T_J,T_m,T_eD is the power angle, the angular velocity, the moment of inertia, the mechanical torque, the electromagnetic torque and the damping coefficient of the generator in sequence; p is a differential operator;

let p be 0 in formula (3) to obtain the steady state equation of the generator

Let k₁＝X′_d-X″_d,

Of formula (II) to (III)'_q0,e″_q0,e′_d0,e″_d0Respectively setting the initial values of generator AC-DC axis transient state and sub-transient state electromotive force;

converting the 3 rd expression and the 5 th expression in the equation set of the formula (5) into e ″_qAnd e ″)_dIs expressed as

Substituting the formula (6) into the 4 th formula and the 6 th formula in the formula (5) equation set to obtain the formula

Converting equations 1 and 2 in equation set of equation (5) to e ″_qAnd e ″)_dIs expressed as

Similarly, the transient electromotive force e 'of the generator is given when the damping loop is not counted'_qAnd e'_dIs expressed as

Similarly, the initial values e 'of the generator AC-DC shaft transient state and sub-transient state electromotive force'_q0,e″_q0,e′_d0,e″_d0Also represented by formula (8) and formula (9); e'_q,e″_q,e′_q0,e″_q0,e′_d,e″_d,e′_d0,e″_d0The expression is also substituted for formula (7).

4. The method as claimed in claim 3, wherein the generator practical parameter identification model is established by a method comprising the following steps: the step S2 specifically includes the following steps:

order to

In the formula u_d0,u_q0,i_d0,i_q0The components of steady-state voltage and current at the generator end before disturbance occurs on the d axis and the q axis respectively; equations (10) to (11) are the practical generator parameter identification models taking saturation characteristics into account.

5. The method for identifying a generator utility parameter identification model considering saturation characteristics as claimed in claim 4, wherein: firstly, discretizing the identification model, and constructing an optimization function taking the minimum difference value between a calculated value and an actually measured value of dq axis current as a target; then, on the basis of the optimization function, the identification method comprises the following steps:

step SA: performing per unit on the measurement data of a synchronous Phasor Measurement Unit (PMU);

step SB: substituting the measured data processed in the step SA into formula (4) to solve the steady-state parameters;

step SC: providing generator nameplate parameters of manufacturers as initial values of identification parameters;

step SD: the steady state parameter X_d,X_qIn the substituted optimization function, solving by adopting a genetic algorithm to obtain transient and sub-transient parameters of dq axes;

step SE: if the difference value between the dq axis current value output by the generator parameter identification model and the actual current value meets the requirement of 2.5% of error, finishing iteration and outputting the transient state and the sub-transient state parameters of the dq axis of the generator; and if the requirements are not met, performing next iteration and repeating the step SD.

6. The method as claimed in claim 5, wherein the generator utility parameter identification model is a generator utility parameter identification model based on saturation characteristics, and comprises: discretizing the identification model, and constructing an optimization function taking the minimum difference value between a calculated value and an actually measured value of the dq axis current as a target; the concrete contents are as follows:

discretizing the equations (1) to (2), taking the fitted value of the dq-axis current and the difference value of the measured values as the construction function of the optimization target value, and setting the identified boundary conditions, wherein the boundary conditions are expressed as:

wherein, the formula (12) to the formula (13) are optimization functions, t_nRepresents the nth sampling instant; n is the total sampling point number; the parameter containing subscript c is a parameter value given by a manufacturer; boundary condition limitation identification parameter X'_q,X″_q,T′_q0,T″_q0,X′_d,X″_d,T′_d0,T″_d0In the range of 0.7 to 1.3 times the parameters given by the manufacturer.

Technical Field

The invention relates to the field of generator practical parameter identification precision, in particular to a generator practical parameter identification model considering saturation characteristics and an identification method thereof.

Background

China is accelerating the fine modeling work of a propulsion power system, wherein the work of warehousing an excitation speed regulation system and PSS parameters is perfected year by year, but the parameters of a synchronous generator still adopt nameplate parameters for simulation calculation. The accuracy of the generator model parameters is an important factor causing the deviation of the time domain simulation result of the power system and the actual situation, and the hidden danger investigation, the accident recurrence, the safety and the stability and the planning design of the system are directly influenced. In recent years, the realization of online identification of model parameters of a power system by using a synchronous phasor measurement unit (pmu) becomes an important research direction, the pmu has the characteristic of measuring real-time state variables of a generator, the decoupling of the generator and a power grid, an excitation system and a speed regulation system can be realized, an identification strategy can be optimized, measured system disturbance data is taken into consideration of the real operation condition of the generator, and the reliability is high.

In the practical model unobservable quantity andin the aspect of processing the derivative term, the domestic scholars provide a time-frequency transformation processing method suitable for the load shedding test, the differential equation set of the practical model is transformed into an integral equation, an intermediate variable is eliminated, an equation only containing the observable electric quantity and the parameter to be identified is constructed, and the error of repeated iteration of the intermediate variable is avoided. Wherein the proposed excitation induced electromotive force e_fThe correction method takes account of the influence of the saturation characteristic of the generator on the parameter identification precision. However, the method needs to use the composite value I of the exciting current and the armature current_f∑Vector superposition resultant I due to abrupt change of armature current during disturbance_f∑The real-time value has errors at the moment of mutation, and the identification precision is influenced.

Disclosure of Invention

In view of this, the present invention provides a generator practical parameter identification model considering saturation characteristics and an identification method thereof, in which the parameter identification model is a dq decoupling equation, so as to reduce the dimension of parameter identification, avoid the calculation process of repeated iteration of unobservable state variables, and improve the rapidity of identification.

The invention is realized by adopting the following scheme: a generator practical parameter identification model considering saturation characteristics specifically comprises:

in the formula, X_q,X′_q,X″_q,T′_q0,T″_q0Quadrature-axis synchronous reactance, quadrature-axis transient and sub-transient open-circuit time constants, respectively; x_d,X′_d,X″_d,T′_d0,T″_d0Respectively time constants of a direct-axis synchronous reactance, a direct-axis transient reactance, a sub-transient reactance, a direct-axis transient and a sub-transient open circuit; said X_q,X′_q,X″_q,T′_q0,T″_q0And said X_d,X′_d,X″_d,T′_d0,T″_d0Are all identification parameters; x_lIs stator leakage reactance; i.e. i_d,i_qThe components of the generator terminal current in the d axis and the q axis are respectively; e.g. of the type_fInduced electromotive force is excited; order to

In the formula u_d0,u_q0,i_d0,i_q0The components of steady-state voltage and current at the generator end before disturbance occurs in d and q axes; order tok₃＝1+S_d，

S_d,S_qRespectively d-axis and q-axis saturation factors.

Further, the invention also provides a method for establishing the generator practical parameter identification model based on the saturation characteristics, which comprises the following steps:

step S1: converting a six-order practical time domain model equation set of the generator into a frequency domain model equation set by using Laplace transformation, carrying out algebraic transformation on the frequency domain equation set, and eliminating an unobservable quantity e'_q,e″_q,e′_q0,e″_q0,e′_d,e″_d,e′_d0,e″_d0；

Step S2: and (4) performing Laplace inverse transformation on the equation set obtained by eliminating the unobservable quantity in the step S1, and converting the equation set into a generator practical parameter identification model which is expressed in an integral form, eliminates the unobservable quantity and takes saturation characteristics into account.

Further, the step S1 specifically includes the following steps:

ignoring electromagnetic transients and armature resistance R of the stator winding_aConsidering transient process of an excitation winding f, a rotor d and a q shaft and saturation characteristics of the generator, and considering the influence of the saturation characteristics, the six-order practical model of the synchronous generator is as follows:

in the formula, X_q,X′_q,X″_q,T′_q0,T″_q0Quadrature-axis synchronous reactance, quadrature-axis transient and sub-transient open-circuit time constants, respectively; x_d,X′_d,X″_d,T′_d0,T″_d0Respectively time constants of a direct-axis synchronous reactance, a direct-axis transient reactance, a sub-transient reactance, a direct-axis transient and a sub-transient open circuit; said X_q,X′_q,X″_q,T′_q0,T″_q0And said X_d,X′_d,X″_d,T″_d0,T″_d0Are all identification parameters; x_lIs stator leakage reactance; u. of_d,i_d,u_q,i_qThe components of the voltage and the current at the generator terminal on the d axis and the q axis are respectively; e.g. of the type_fInduced electromotive force is excited; e'_q,e″_q,e′_d,e″_dThe electromotive forces are respectively alternating-current, direct-axis transient and sub-transient of the generator and are state variables; s_d,S_qD-axis and q-axis saturation factors respectively; delta, omega, T_J,T_m,T_eD is the power angle, the angular velocity, the moment of inertia, the mechanical torque, the electromagnetic torque and the damping coefficient of the generator in sequence; p is a differential operator;

let p be 0 in formula (3) to obtain the steady state equation of the generator

Let k₁＝X′_d-X″_d,k₄＝X′_q-X″_q,k₆＝1+S_qAnd subjecting the formula (3) to Laplace transformation to obtain

Of formula (II) to (III)'_q0,e″_q0,e′_d0,e″_d0Respectively setting the initial values of generator AC-DC axis transient state and sub-transient state electromotive force;

converting the 3 rd expression and the 5 th expression in the equation set of the formula (5) into e ″_qAnd e ″)_dIs expressed as

Substituting the formula (6) into the 4 th formula and the 6 th formula in the formula (5) equation set to obtain the formula

Converting equations 1 and 2 in equation set of equation (5) to e ″_qAnd e ″)_dIs expressed as

Similarly, the transient electromotive force e 'of the generator is given when the damping loop is not counted'_qAnd e'_dIs expressed as

Similarly, the initial values e 'of the generator AC-DC shaft transient state and sub-transient state electromotive force'_q0,e″_q0,e′_d0,e″_d0Also represented by formula (8) and formula (9); e'_q,e″_q,e′_q0,e″_q0,e′_d,e″_d,e′_d0,e″_d0The expression is also substituted for formula (7).

Further, the step S2 specifically includes the following steps:

order to

Substitution formula (7), and finally inverse Laplace transform is performed on formula (7) to remove the unobservable quantity e'_q,e″_q,e′_q0,e″_q0,e′_d,e″_d,e′_d0,e″_d0To obtain

In the formula u_d0,u_q0,i_d0,i_q0The components of steady-state voltage and current at the generator end before disturbance occurs on the d axis and the q axis respectively; equations (10) to (11) are the practical generator parameter identification models taking saturation characteristics into account.

Furthermore, the invention also provides an identification method of the generator practical parameter identification model considering the saturation characteristic, firstly, discretizing the identification model, and constructing an optimization function taking the minimum difference value between a calculated value and an actually measured value of dq axis current as a target; then, on the basis of the optimization function, the identification method comprises the following steps:

step SA: performing per unit on the measurement data of a synchronous Phasor Measurement Unit (PMU);

step SB: substituting the measured data processed in the step SA into formula (4) to solve the steady-state parameters;

step SC: providing generator nameplate parameters of manufacturers as initial values of identification parameters;

step SD: the steady state parameter X_d,X_qSubstituting equations (12) to (13), and solving by adopting a genetic algorithm to obtain transient and sub-transient parameters of the dq axis;

step SE: if the difference value between the dq axis current value output by the generator parameter identification model and the actual current value meets the requirement of 2.5% of error, finishing iteration and outputting the transient state and the sub-transient state parameters of the dq axis of the generator; and if the requirements are not met, performing next iteration and repeating the step SD.

Further, discretizing the identification model, and constructing an optimization function taking the minimum difference value between a calculated value and an actually measured value of the dq axis current as a target; the method specifically comprises the following steps:

discretizing the equations (1) to (2), taking the fitted value of the dq-axis current and the difference value of the measured values as the construction function of the optimization target value, and setting the identified boundary conditions, wherein the boundary conditions are expressed as:

wherein, t_nRepresents the nth sampling instant; n is the total sampling point number; the parameter containing subscript c is a parameter value given by a manufacturer; boundary condition limitation identification parameter X'_q,X″_q,T′_q0,T″_q0,X′_d,X″_d,T′_d0,T″_d0In the range of 0.7 to 1.3 times the parameters given by the manufacturer.

Compared with the prior art, the invention has the following beneficial effects:

(1) the practical parameter identification model is a dq decoupling equation, reduces the dimension of parameter identification, avoids the calculation process of repeated iteration of unobservable state variables, and improves the rapidity of identification.

(2) The integral equation form of the invention avoids the problem of local linearization in the process of large disturbance, and improves the stability of identification.

(3) The model of the invention is a direct derivation of the six-order practical saturation model of the generator, no new hypothesis is added in the derivation process, the saturation characteristic of the generator is taken into account, the model avoids errors caused by repeated iteration of unobservable state variables, and the identification precision is improved.

Drawings

Fig. 1 is a flow chart of synchronous generator parameter identification according to an embodiment of the present invention.

Fig. 2 is a diagram illustrating comparison between dq-axis simulated current and fitted current under a single-phase ground fault according to an embodiment of the present invention, where fig. 2(a) is a diagram illustrating comparison between d-axis simulated current and fitted current, and fig. 2(b) is a diagram illustrating comparison between q-axis simulated current and fitted current.

Fig. 3 is a comparison graph of dq-axis simulated current and fitted current under a three-phase short-circuit fault according to an embodiment of the present invention, where fig. 3(a) is a comparison graph of d-axis simulated current and fitted current, and fig. 3(b) is a comparison graph of q-axis simulated current and fitted current.

Fig. 4 is a comparison graph of current calculated by dq axis actual measurement and identification value and nameplate value under power fluctuation in the embodiment of the present invention, in which fig. 4(a) is a comparison graph of current calculated by d axis actual measurement and identification value and nameplate value, and fig. 4(b) is a comparison graph of current calculated by q axis actual measurement and identification value and nameplate value.

Detailed Description

The invention is further explained below with reference to the drawings and the embodiments.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The embodiment provides a generator practical parameter identification model considering saturation characteristics, which specifically comprises:

in the formula, X_q,X′_q,X″_q,T′_q0,T″_q0Quadrature-axis synchronous reactance, quadrature-axis transient and sub-transient open-circuit time constants, respectively; x_d,X′_d,X″_d,T′_d0,T″_d0Respectively time constants of a direct-axis synchronous reactance, a direct-axis transient reactance, a sub-transient reactance, a direct-axis transient and a sub-transient open circuit; said X_q,X′_q,X″_q,T′_q0,T″_q0And said X_d,X′_d,X″_d,T′_d0,T″_d0Are all identification parameters; x_lIs stator leakage reactance; i.e. i_d,i_qThe components of the generator terminal current in the d axis and the q axis are respectively; e.g. of the type_fInduced electromotive force is excited; order toIn the formula u_d0,u_q0,i_d0,i_q0The components of steady-state voltage and current at the generator end before disturbance occurs in d and q axes; order to

k₃＝1+S_d，

S_d,S_qRespectively d-axis and q-axis saturation factors.

Preferably, the embodiment further provides a method for establishing a generator practical parameter identification model based on the saturation characteristics, including the following steps:

step S1: converting a six-order practical time domain model equation set of the generator into frequency by using Laplace transformationThe domain model equation set is subjected to algebraic transformation, and the unobservable quantity e 'is eliminated'_q,e″_q,e′_q0,e″_q0,e′_d,e″_d,e′_d0,e″_d0；

Step S2: and (4) performing Laplace inverse transformation on the equation set obtained by eliminating the unobservable quantity in the step S1, and converting the equation set into a generator practical parameter identification model which is expressed in an integral form, eliminates the unobservable quantity and takes saturation characteristics into account.

In this embodiment, the step S1 specifically includes the following steps:

ignoring electromagnetic transients and armature resistance R of the stator winding_aConsidering transient process of an excitation winding f, a rotor d and a q shaft and saturation characteristics of the generator, and considering the influence of the saturation characteristics, the six-order practical model of the synchronous generator is as follows:

in the formula, X_q,X′_q,X″_q,T′_q0,T″_q0Quadrature-axis synchronous reactance, quadrature-axis transient and sub-transient open-circuit time constants, respectively; x_d,X′_d,X″_d,T′_d0,T″_d0Respectively time constants of a direct-axis synchronous reactance, a direct-axis transient reactance, a sub-transient reactance, a direct-axis transient and a sub-transient open circuit; said X_q,X′_q,X″_q,T′_q0,T″_q0And said X_d,X′_d,X″_d,T′_d0,T″_d0Are all identification parameters; x_lIs stator leakage reactance; u. of_d,i_d,u_q,i_qThe components of the voltage and the current at the generator terminal on the d axis and the q axis are respectively; e.g. of the type_fInduced electromotive force is excited; e'_q,e″_q,e′_d,e″_dThe electromotive forces are respectively alternating-current, direct-axis transient and sub-transient of the generator and are state variables; s_d,S_qD-axis and q-axis saturation factors respectively; delta, omega, T_J,T_m,T_eD is the power angle, the angular velocity, the moment of inertia, the mechanical torque, the electromagnetic torque and the damping coefficient of the generator in sequence; p is a differential operator;

let p be 0 in formula (3) to obtain the steady state equation of the generator

Let k₁＝X′_d-X″_d,k₄＝X′_q-X″_q,

k₆＝1+S_qAnd subjecting the formula (3) to Laplace transformation to obtain

Of formula (II) to (III)'_q0,e″_q0,e′_d0,e″_d0Respectively setting the initial values of generator AC-DC axis transient state and sub-transient state electromotive force;

converting the 3 rd expression and the 5 th expression in the equation set of the formula (5) into e ″_qAnd e ″)_dIs expressed as

Substituting the formula (6) into the 4 th formula and the 6 th formula in the formula (5) equation set to obtain the formula

Converting equations 1 and 2 in equation set of equation (5) to e ″_qAnd e ″)_dIs expressed as

Similarly, the transient electromotive force e 'of the generator is given when the damping loop is not counted'_qAnd e'_dIs expressed as

Similarly, the initial values e 'of the generator AC-DC shaft transient state and sub-transient state electromotive force'_q0,e″_q0,e′_d0,e″_d0Also represented by formula (8) and formula (9); e'_q,e″_q,e′_q0,e″_q0,e′_d,e″_d,e′_d0,e″_d0The expression is also substituted for formula (7).

In this embodiment, the step S2 specifically includes the following steps:

order to

And substitution into formula (7), and finally inverse Laplace transform is performed on formula (7) to remove the unobservable quantity e'_q,e″_q,e′_q0,e″_q0,e′_d,e″_d,e′_d0,e″_d0To obtain

In the formula u_d0,u_q0,i_d0,i_q0The components of steady-state voltage and current at the generator end before disturbance occurs on the d axis and the q axis respectively; equations (10) to (11) are the practical generator parameter identification models taking saturation characteristics into account. It can be seen that the generator practical parameter identification model expressed in the form of the integral equation only contains the electric quantity of the dq axis of the generator and the parameter to be identified, the electric quantity of the dq axis is calculated by PMU measurement data, and the model is suitable for online identification.

In this embodiment, the identification model is discretized to construct an optimization function with the minimum difference between the calculated value and the measured value of the dq-axis current as a target; the concrete contents are as follows:

the generator parameter identification is converted into a nonlinear optimization problem, the equations (1) to (2) are discretized, the fitted value and the actually measured value difference value of the dq axis current are minimum to serve as an optimization target value construction function, and the identified boundary conditions are set and expressed as follows:

wherein, the formula (12) to the formula (13) are optimization functions, t_nRepresents the nth sampling instant; n is the total sampling point number; the parameter containing subscript c is a parameter value given by a manufacturer; boundary condition limitation identification parameter X'_q,X″_q,T′_q0,T″_q0,X′_d,X″_d,T′_d0,T″_d0In the range of 0.7 times to 1.3 times of the parameters given by manufacturers, the method is enough to meet the requirements of engineering application.

Because the dq axle of synchronous generator nature decoupling zero characteristic, can separately discern d, q axle parameter in the parameter identification process, reduced the optimization variable number that the single was discerned, further adopt this embodiment the generator practical parameter of taking into account saturation characteristic and discern the model, can separately discern synchronous generator steady state parameter and transient state/time transient state parameter for distinguish the variable that optimizes at every turn and reduce to 4 in the parameter identification process. By adopting the identification strategy of dq axis parameter decoupling and transient and steady state parameter stepping, the optimization dimension in the parameter identification process can be obviously reduced, the parameter identification precision can be improved, and the parameter identification process of the synchronous generator is shown in figure 1.

And synthesizing the optimized identification model to form a generator parameter identification strategy based on PMU measurement data.

Preferably, the embodiment further provides an identification method of a generator practical parameter identification model based on saturation characteristics, first discretizing the identification model, and constructing an optimization function with a minimum difference value between a calculated value and an actually measured value of dq axis current as a target; then, on the basis of the optimization function, the identification method comprises the following steps:

step SA: performing per-unit preprocessing on the data measured by the PMU of the synchronous phasor measurement device;

step SB: substituting the measured data processed in the step SA into formula (4) to solve the steady-state parameters;

step SC: providing generator nameplate parameters of manufacturers as initial values of identification parameters;

step SD: the steady state parameter X_d,X_qSubstituting equations (12) to (13), and solving by adopting a genetic algorithm to obtain transient and sub-transient parameters of the dq axis;

step SE: if the difference value between the dq axis current value output by the generator parameter identification model and the actual current value meets the error requirement, finishing iteration and outputting the transient state and the sub-transient state parameters of the dq axis of the generator; and if the requirements are not met, performing next iteration and repeating the step SD.

In particular, the present embodiment also provides the best mode for performing mathematical verification. The arithmetic verification is divided into simulation examples and actual measurement verification.

A2018 typical operation mode of a certain power grid built by PSD-BPA is adopted, a 0.5s single-phase earth fault and a three-phase short-circuit fault are set at an outlet of a power plant generator set, and a parameter identification model respectively takes saturation characteristics and non-saturation characteristics into consideration. The dq axis simulation and fitting current curves are shown in fig. 2-3, and the parameter identification results are detailed in table 1.

As can be seen from fig. 2 to fig. 3, for typical symmetric or asymmetric faults and disturbance data after fault recovery, the dq-axis fitting current output by the generator practical parameter identification at 10ms sampling intervals is highly consistent with the simulation current curve.

TABLE 1 comparison of parameter identification results based on different simulation fault data

As can be seen from fig. 2 to 3, for typical symmetric or asymmetric faults and disturbance data after fault recovery, the dq-axis fitting current output by the generator practical parameter identification model considering the saturation characteristic is highly consistent with the simulation current curve. As can be seen from Table 1, the error of the identification result of the parameter identification model considering the saturation characteristic is less than 2.5%, and the T' of the unsaturated characteristic model_q0The identification result is not in accordance with the set value, which results in large root mean square error, and the model accuracy has a large influence on the parameter identification result. From the above analysis, the generator practical parameter identification model considering the saturation characteristic has universality for different fault types, and the parameter identification result has high precision.

Verification of actual measurement

In order to further verify the effectiveness of the parameter identification method, the effectiveness of the identification method is verified by adopting actual measurement PMU disturbance data of the Fujian Nanbu power plant. The disturbance occurs in the switching process of the unit from a single valve to a forward valve, and is affected by nonlinear influence of the flow of the regulating valve in the valve switching process, the speed regulating system generates negative damping on the unit, and when the frequency of a power grid is reduced to cause the action of the speed regulating system, the power of the unit fluctuates greatly due to primary frequency regulation overshoot. During the switching period of the valve, along with the reduction of the power grid frequency for many times, the unit frequency difference exceeds the dead zone for many times, the speed regulating system frequently acts, and the corresponding PMU device records multiple groups of disturbance data. The invention is used for calculating the dq axis current, the nameplate value is used for calculating the dq axis current, and the comparison with the current measured current is shown in figure 4.

As can be seen from fig. 4, compared with the data plate parameter, the current fitting effect calculated by the identification value is better than that of the data plate value, the accuracy of the parameter identification value is proved, and the generator practical parameter identification model and identification method considering the saturation characteristic can effectively improve the identification precision.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.