Method for determining control parameter stability region of power system stabilizer of generator

Abstract

Provided in the present disclosure is a method for determining a control parameter stability region of a power system stabilizer (PSS) of a generator. The method comprises the following steps: S1, acquiring parameters of a generator, an excitation system, a PSS and a grid-connected power system; S2, on the basis of the parameters, determining a system state variable x, a control variable and an intermediate variable u, and on the basis of a system stable-state calculation result, initializing the generator, the excitation system, the PSS and the grid-connected power system; S3, obtaining an operating power system model; S4, extracting a small-disturbance stability analysis model; S5, constructing and initializing a system control parameter space; S6, performing a search and evaluating the trajectory stability of each operating point in a specified direction; and S7, adjusting a control parameter search direction, and determining a set of control parameter stability region boundaries.

Description

Generator power system stabilizer control parameter stability domain determination method

[0001] Cross-reference to Related Applications

[0002] The present disclosure claims priority to Chinese Patent Application No. 202410715274.2, filed on June 04, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure belongs to the technical field of generator power system stabilizer, and particularly relates to a generator power system stabilizer control parameter stability domain determination method. BACKGROUND

[0004] With the wide application of extra-high voltage AC / DC power transmission technology, the large-scale regional interconnection of power grids has made great progress. At the same time, due to large-scale cross-regional power transmission, small signal stability problems represented by low-frequency oscillation and ultra-low-frequency oscillation in power systems are becoming increasingly serious. In order to suppress oscillation in the power grid and improve the small signal stability of the power system, it is usually necessary to install controllers such as power system stabilizer (PSS) and speed governor.

[0005] The effect of power system stabilizer (PSS) in suppressing low-frequency oscillation depends on the type and parameters of PSS. There are mainly two types of methods for PSS control parameter setting: one is the phase compensation method based on frequency domain, which needs to calculate the phase lag caused by the excitation link, and the effect of compensating the lagging phase is achieved through the leading-lagging link of PSS, which injects positive damping into the system to improve the system damping; the other type of PSS parameter setting method is mainly based on various optimization methods, such as linear optimization, nonlinear optimization and intelligent optimization algorithm, etc., which usually selects PSS parameters as part of the objective function or directly as optimization variables to select its parameters. However, the above two types of methods cannot conveniently depict the range of PSS control parameters to ensure the normal operation of the system, nor can they intuitively reflect the stability margin of the current operating state and control parameters, i.e., how far it is from the unstable space. In view of this, there is an urgent need for a new method that can monitor and monitor the system operation state according to the system operation state and guide the safe operation of the system.

[0006] SUMMARY

[0007] The purpose of the present disclosure is to provide a generator power system stabilizer control parameter stability domain determination method, which solves the problem that the prior art cannot intuitively reflect the stability margin of the current operating state and control parameters.

[0008] The technical solution adopted by the present disclosure is a generator power system stabilizer control parameter stability domain determination method, comprising the following steps:

[0009] S1, obtaining parameters of a generator, an excitation, a power system stabilizer (PSS) and a grid-connected power system;

[0010] S2, taking a single-machine infinite-bus system, determining system state variables x, control variables and intermediate variables u according to parameters of the grid-connected power system, and initializing the generator, the excitation, the power system stabilizer (PSS) and the grid-connected power system according to a system steady-state calculation result;

[0011] S3, obtaining a running power system model, and establishing a differential algebraic equation of the running power system model;

[0012] S4, extracting a small disturbance stability analysis model according to the differential algebraic equation of the running power system model, and obtaining a system small disturbance stability analysis state equation;

[0013] S5, constructing and initializing a system control parameter space;

[0014] S6, searching and evaluating trajectory stability of each operating point in a specified direction;

[0015] S7, adjusting a search direction of the control parameter, and determining a control parameter stability domain boundary set.

[0016] The disclosure is also characterized in that:

[0017] The parameters in S1 specifically include: generator operation parameters and control parameters, excitation system operation and control parameters, power system stabilizer (PSS) operation and control parameters, and grid-connected power system topology, control parameters and boundary conditions, and the grid-connected power system topology, control parameters and boundary conditions include load positions and types.

[0018] The specific method of S2 is: taking a single-machine infinite-bus system, determining system state variables x, control variables and intermediate variables u according to the grid-connected power system topology, load positions and types, and initializing the generator, the excitation, the power system stabilizer (PSS) and the grid-connected power system according to a system steady-state calculation result.

[0019] The running power system model in S3 includes a generator system model, an excitation system model, a power system stabilizer (PSS) model and a grid-connected power system model in the form of a differential algebraic equation; the generator system model is represented as:

[0020] wherein x SM represents a generator state variable, u SM represents a generator control variable, represents a differential of the generator state variable with respect to time t, f SM and g SM respectively represent functions with respect to x SM and u SM ;

[0021] The excitation system model is represented as:

[0022] where x EX represents excitation state variables, u EX represents excitation control variables, represents the differential of the excitation state variables with respect to time t, f EX and g EX represent functions of x EX and u EX respectively;

[0023] The power system stabilizer (PSS) model is represented as:

[0024] where x PSS represents PSS state variables, u PSS represents PSS control variables, represents the differential of the PSS state variables with respect to time t, f PSS and g PSS represent functions of x PSS and u PSS respectively;

[0025] The differential algebraic equations of the operating power system model are:

[0026] where x represents system state variables, represents the differential of the system state variables with respect to time t, x = [x SM , x EX , x PSS , x SYS ] T ; u represents PSS control variables, u = [u SM , u EX , u PSS , u SYS ] T , x SYS and u SYS represent power system state variables and algebraic variables respectively.

[0027] The specific method for obtaining the system small disturbance stability analysis state equation in S4 is:

[0028] The Taylor expansion of the state equations of the generator system model, the excitation system model, the power system stabilizer (PSS) model and the operating power system model of the grid-connected power system model at the operating point (x0, u0) is performed and the high-order terms are ignored, to obtain the linearized equation at the operating point:

[0029] wherein, Δx, Δu are the incremental form of the time differential of the system state variable, the incremental form of the system state variable and the incremental form of the system control variable respectively,

[0030] Eliminate the control variable u to obtain the system small disturbance stability analysis state equation:

[0031] wherein, the matrix A-BD -1 C is the system state matrix.

[0032] The specific method of S5 is: according to the parameter operating range of the power system stabilizer PSS control parameter and the operating point in the system small disturbance stability analysis state equation, a system control parameter space is constructed.

[0033] The specific method of S6 is: starting from the operating equilibrium point, the eigenvalues of the system state matrix are calculated along the current parameter prescribed direction, and the small disturbance stability condition is analyzed according to the distribution of the dominant eigenvalue in the complex plane, which specifically includes:

[0034] S6.1, in the selected control parameter space, adjust the corresponding control parameter from the current stable operating point along the prescribed direction with the current step size to obtain a new set of equilibrium points;

[0035] S6.2, calculate the eigenvalues of the system state matrix at the equilibrium point, and in response to the dominant eigenvalue real part being negative, continue to execute S6.1; otherwise, go to S6.3;

[0036] S6.3, in response to the control parameter meeting the convergence precision, record the current operating point as the boundary point of the control parameter stability domain in the current search direction; otherwise, back to the previous operating point and reduce the step size to 1 / 4 of the current step size, return to S6.1.

[0037] The specific method of S7 is: after the current control parameter search direction is completed or has met the jump to the current step of S6.3, the search direction is changed, and S6 is executed again until each direction of the selected control parameter space is traversed, and a control parameter stability domain boundary set meeting the accuracy requirement is obtained, that is, the power system stabilizer control parameter stability boundary including the generator, excitation and grid-connected system can be drawn, and the power system stabilizer control parameter stability domain is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0038] FIG. 1 is a flowchart of the method for determining the control parameter stability domain of the generator power system stabilizer according to the present disclosure;

[0039] FIG. 2 is a 2B model diagram of the power system stabilizer PSS according to the present disclosure;

[0040] Figure 3 is a stable domain result map in the lead-lag element time constant T1, T2 control parameter space of Example 4;

[0041] Figure 4 is a simulation result map of generator speed under different control parameters of Example 4;

[0042] Figure 5 is a simulation result map of generator power under different control parameters of Example 4. DETAILED DESCRIPTION

[0043] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] The motor power system stabilizer control parameter stable domain determination method provided by the embodiments of the present disclosure is shown in Figure 1, which includes the following steps:

[0045] S1, obtaining the parameters of the generator, excitation, power system stabilizer PSS and grid-connected power system;

[0046] The parameters specifically include: generator operating parameters and control parameters, excitation system operating and control parameters, power system stabilizer PSS operating and control parameters, and grid-connected power system topology, control parameters and boundary conditions, and the grid-connected power system topology, control parameters and boundary conditions include load location and type.

[0047] S2, taking a single-machine infinite system, determining system state variables x, control variables and intermediate variables u according to the grid-connected power system topology, load location and type, and initializing the generator, excitation, power system stabilizer PSS and grid-connected power system according to the system steady-state calculation results. As an example, based on the parameters obtained in step S1, the system steady-state flow calculation is performed in combination with the "grid-connected power system topology, load location and type" in step S2, and the steady-state calculation results are used as initial conditions, thereby realizing the initialization of the generator, excitation, power system stabilizer PSS and grid-connected power system.

[0048] S3, obtaining an operating power system model, and establishing a differential algebraic equation of the operating power system model;

[0049] The operating power system model includes a generator system model, an excitation system model, a power system stabilizer PSS model and a grid-connected power system model in the form of a differential algebraic equation; the generator system model is represented as:

[0050] wherein x SM represents the generator state variable, u SM represents the generator control variable, represents the differential of the generator state variable with respect to time t, fSM and g SM represent functions of x SM and u SM respectively; it is to be noted that in embodiments of the present disclosure, the functions f and g can be determined according to the actual generator, excitation, PSS, system model used, and the method according to embodiments of the present disclosure can be used as a general mode of the stability domain determination method.

[0051] The excitation system model is expressed as:

[0052] where x EX represents an excitation state variable, u EX represents an excitation control variable, represents the differential of the excitation state variable with respect to time t, f EX and g EX represent functions of x EX and u EX respectively;

[0053] FIG. 2 shows a general PSS model published by the Institute of Electrical and Electronics Engineers (IEEE) in 2005, as shown in FIG. 2, the power system stabilizer PSS model is expressed as:

[0054] where x PSS represents a PSS state variable, u PSS represents a PSS control variable, represents the differential of the PSS state variable with respect to time t, f PSS and g PSS represent functions of x PSS and u PSS respectively; specifically, before the transfer function output, there can be an output limiter (e.g. upper and lower limit constraints) which can be a nonlinear constraint, and under the condition of ignoring such limit, the excitation, PSS model can be expressed in the form of the differential algebraic equation group described above.

[0055] The differential algebraic equation of the operating power system model is:

[0056] where x represents a system state variable, represents the differential of the system state variable with respect to time t, x = [x SM , x EX , x PSS , x SYS ] T ; u represents a PSS control variable, u = [u SM , uEX , u PSS , u SYS ] T , x SYS and u SYS denote power system state variables and algebraic variables respectively, and f and g denote functions with respect to x and u respectively;

[0057] S4, extracting a small disturbance stability analysis model according to the differential-algebraic equation of the running power system model to obtain a system small disturbance stability analysis state equation;

[0058] The specific method for obtaining the system small disturbance stability analysis state equation is: performing Taylor expansion on the state equation of the running power system model of the generator system model, the excitation system model, the power system stabilizer PSS model and the grid-connected power system model at the operating point (x0, u0) and ignoring high-order terms to obtain a linearized equation at the operating point:

[0059] wherein, Δx, Δu are respectively an incremental form of the time differential of the system state variable, an incremental form of the system state variable and an incremental form of the system control variable,

[0060] Eliminating the control variable u, the system small disturbance stability analysis state equation is obtained:

[0061] wherein, the matrix A-BD -1 C is a system state matrix;

[0062] S5, constructing and initializing a system control parameter space;

[0063] According to the parameter running range of the power system stabilizer PSS control parameter and the operating point in the system small disturbance stability analysis state equation, a system control parameter space is constructed;

[0064] S6, searching and evaluating the trajectory stability of each operating point in a specified direction;

[0065] Starting from the operating equilibrium point, the eigenvalues of the system state matrix are calculated along the current parameter specified direction, and the small disturbance stability is analyzed according to the distribution of the dominant eigenvalue in the complex plane. Here, the parameter specified direction can be selected autonomously during calculation, and the embodiments of the present disclosure do not limit the parameter specified direction. In addition, based on the system state matrix, the eigenvalues of the matrix can be calculated at the current operating equilibrium point, and the eigenvalue with the largest real part can be selected as the dominant eigenvalue from the obtained eigenvalues. This step S6 specifically includes:

[0066] S6.1, adjusting the corresponding control parameter in the selected control parameter space from the current stable operating point in a specified direction with a current step size to obtain a new set of equilibrium points;

[0067] S6.2, calculating the eigenvalues of the system state matrix of the equilibrium points, and if the real part of the dominant eigenvalue is negative, continuing to perform S6.1; otherwise, turning to S6.3;

[0068] S6.3, if the control parameter meets the convergence accuracy, recording the current operating point as a boundary point of the stable region of the control parameter in the current search direction; otherwise, backtracking to the previous operating point and reducing the step size to 1 / 4 of the current step size, and returning to S6.1.

[0069] S7, adjusting the search direction of the control parameter to determine the boundary set of the control parameter stable region;

[0070] After the current control parameter search direction is completed or has met the jump to the current step in S6.3, the search direction is changed, and S6 is executed again until each direction of the selected control parameter space is traversed, and a control parameter stable region boundary set meeting the accuracy requirement is obtained, that is, the control parameter stable boundary of the power system stabilizer including the generator, the excitation, and the grid-connected system is drawn, and the control parameter stable region of the power system stabilizer is obtained. The stable region reflects the operating stability of the system in the control parameter control space of the power system stabilizer, that is, each parameter combination in the stable region is stable, each parameter combination outside the stable region is unstable, and the boundary of the stable region is composed of system stability critical points.

[0071] The generator power system stabilizer control parameter stable region determination method of the embodiments of the present disclosure solves the problem that the prior art cannot intuitively reflect the stability margin of the current operating state and the control parameter.

[0072] Embodiment 1

[0073] The motor power system stabilizer control parameter stable region determination method proposed in this embodiment, as shown in FIG. 1, includes the following steps:

[0074] S1, obtaining the parameters of the generator, the excitation, the power system stabilizer PSS, and the grid-connected power system;

[0075] S2, taking a single-machine infinite system, determining the system state variable x, the control variable and the intermediate variable u according to the parameters of the grid-connected power system, and initializing the generator, the excitation, the power system stabilizer PSS, and the grid-connected power system according to the system steady-state calculation results;

[0076] S3, obtaining the operating power system model, and establishing the differential algebraic equation of the operating power system model;

[0077] S4, extracting a small disturbance stability analysis model according to the differential algebraic equation of the operating power system model, to obtain a system small disturbance stability analysis state equation;

[0078] S5, constructing and initializing a system control parameter space;

[0079] S6, searching and evaluating trajectory stability of each operating point in a specified direction;

[0080] S7, adjusting a search direction of the control parameter to determine a control parameter stability domain boundary set.

[0081] Embodiment 2

[0082] The motor power system stabilizer control parameter stability domain determination method proposed in this embodiment, as shown in FIG. 1, includes the following steps:

[0083] S1, obtaining parameters of a generator, an excitation system, a power system stabilizer PSS and a grid-connected power system;

[0084] The generator operating parameters and control parameters, the excitation system operating and control parameters, the power system stabilizer PSS operating and control parameters, and the grid-connected power system topology, control parameters and boundary conditions, the grid-connected power system topology, control parameters and boundary conditions include load positions and types;

[0085] S2, taking a single-machine infinite system, determining system state variables x, control variables and intermediate variables u according to the grid-connected power system topology, load positions and types, and initializing the generator, the excitation system, the power system stabilizer PSS and the grid-connected power system according to system steady-state calculation results;

[0086] S3, obtaining an operating power system model, and establishing a differential algebraic equation of the operating power system model;

[0087] The operating power system model includes a generator system model, an excitation system model, a power system stabilizer PSS model and a grid-connected power system model in the form of a differential algebraic equation; the generator system model is represented as:

[0088] wherein x SM represents a generator state variable, u SM represents a generator control variable;

[0089] The excitation system model is represented as:

[0090] wherein x EX represents an excitation state variable, u EX represents an excitation control variable;

[0091] As shown in FIG. 2, the power system stabilizer (PSS) model is expressed as:

[0092] where x PSS represents PSS state variables, u PSS represents PSS control variables.

[0093] The differential algebraic equation for running the power system model is:

[0094] where x represents system state variables, x=[x SM , x EX , x PSS , x SYS ] T ; u represents PSS control variables, u=[u SM , u EX , u PSS , u SYS ] T , x SYS and u SYS represent power system state variables and algebraic variables, respectively.

[0095] S4, extracting a small disturbance stability analysis model according to the differential algebraic equation for running the power system model, to obtain system small disturbance stability analysis state equations;

[0096] S5, constructing and initializing a system control parameter space;

[0097] S6, searching and evaluating trajectory stability of each operating point in a specified direction;

[0098] S7, adjusting the search direction of the control parameters to determine a control parameter stability domain boundary set.

[0099] Embodiment 3

[0100] The motor power system stabilizer control parameter stability domain determination method proposed in this embodiment, as shown in FIG. 1, includes the following steps:

[0101] S1, obtaining parameters of a generator, excitation, a power system stabilizer (PSS), and a grid-connected power system;

[0102] The generator operating parameters and control parameters, the excitation system operating and control parameters, the power system stabilizer (PSS) operating and control parameters, and the grid-connected power system topology, control parameters, and boundary conditions, the grid-connected power system topology, control parameters, and boundary conditions include load positions and types.

[0103] S2, take a single machine infinite system, determine system state variables x, control variables and intermediate variables u according to the topology of grid-connected power system, load position and type, and initialize the generator, excitation, power system stabilizer PSS and grid-connected power system according to the steady-state calculation results of the system;

[0104] S3, obtain the operating power system model, and establish the differential algebraic equation of the operating power system model;

[0105] The operating power system model includes a generator system model, an excitation system model, a power system stabilizer PSS model and a grid-connected power system model in the form of differential algebraic equation; the generator system model is represented as:

[0106] Wherein, x SM represents the generator state variable, u SM represents the generator control variable;

[0107] The excitation system model is represented as:

[0108] Wherein, x EX represents the excitation state variable, u EX represents the excitation control variable;

[0109] As shown in FIG. 2, the power system stabilizer PSS model is represented as:

[0110] Wherein, x PSS represents the PSS state variable, u PSS represents the PSS control variable;

[0111] The differential algebraic equation of the operating power system model is:

[0112] Wherein, x represents the system state variable, x=[x SM , x EX , x PSS , x SYS ] T ; u represents the PSS control variable, u=[u SM , u EX , u PSS , u SYS ] T , x SYS and u SYS represent the power system state variable and algebraic variable respectively;

[0113] S4, extract a small disturbance stability analysis model according to the differential algebraic equation of the operating power system model, and obtain a system small disturbance stability analysis state equation;

[0114] The specific method for obtaining the small-disturbance stability analysis state equation of the system is as follows:

[0115] The state equation of the operating power system model of the generator system model, the excitation system model, the power system stabilizer PSS model and the grid-connected power system model is Taylor expanded at the operating point (x0, u0) and high-order terms are ignored to obtain the linearized equation at the operating point:

[0116] wherein,

[0117] The control variable u is eliminated to obtain the small-disturbance stability analysis state equation of the system:

[0118] wherein, the matrix A-BD -1 C is the system state matrix;

[0119] S5, constructing and initializing the system control parameter space;

[0120] According to the parameter operating range of the power system stabilizer PSS control parameter and the operating point in the small-disturbance stability analysis state equation of the system, the system control parameter space is constructed;

[0121] S6, searching and evaluating the trajectory stability of each operating point in the specified direction;

[0122] Starting from the operating equilibrium point, the eigenvalues of the system state matrix are calculated along the current parameter specified direction, and the small-disturbance stability is analyzed according to the distribution of the dominant eigenvalues in the complex plane, which specifically includes:

[0123] S6.1, in the selected control parameter space, the corresponding control parameter is adjusted from the current stable operating point along the specified direction at the current step size to obtain a new set of equilibrium points;

[0124] S6.2, the eigenvalues of the system state matrix at the equilibrium point are calculated, and in response to the dominant eigenvalue real part being negative, S6.1 is continued to be executed; otherwise, S6.3 is turned to;

[0125] S6.3, in response to the control parameter meeting the convergence precision, the current operating point is recorded as the boundary point of the control parameter stability domain in the current search direction; otherwise, the operating point is returned to the previous one and the step size is reduced to 1 / 4 of the current step size, and S6.1 is returned;

[0126] S7, adjusting the search direction of the control parameter, determining the boundary set of the control parameter stability domain;

[0127] After the current control parameter search direction is completed or has met the S6.3 jump to the current step, the search direction is changed, and the S6 is executed again until each direction of the selected control parameter space is traversed, a control parameter stability domain boundary set meeting the accuracy requirement is obtained, and the power system stabilizer control parameter stability boundary of the power system including the generator, the excitation, and the grid-connected system is drawn, and the power system stabilizer control parameter stability domain is obtained.

[0128] Embodiment 4

[0129] The motor power system stabilizer control parameter stability domain determination method provided in the embodiment, as shown in FIG. 1, includes the following steps.

[0130] S1, obtaining the parameters of the generator, the excitation, the power system stabilizer PSS, and the grid-connected power system;

[0131] The generator operating parameters and control parameters, the excitation system operating and control parameters, the power system stabilizer PSS operating and control parameters, and the grid-connected power system topology, control parameters, and boundary conditions, the grid-connected power system topology, control parameters, and boundary conditions include the load position and type;

[0132] S2, taking a single-machine infinite system, determining the system state variable x, the control variable and the intermediate variable u according to the grid-connected power system topology, the load position and type, and initializing the generator, the excitation, the power system stabilizer PSS, and the grid-connected power system according to the system steady-state calculation result;

[0133] S3, obtaining the operating power system model, and establishing the differential algebraic equation of the operating power system model;

[0134] The operating power system model includes the generator system model, the excitation system model, the power system stabilizer PSS model, and the grid-connected power system model in the form of differential algebraic equation; the generator system model is expressed as:

[0135] wherein, x SM represents the generator state variable, u SM represents the generator control variable;

[0136] The excitation system model is expressed as:

[0137] wherein, x EX represents the excitation state variable, u EX represents the excitation control variable;

[0138] The power system stabilizer PSS model is expressed as:

[0139] wherein x PSS represents the PSS state variable, u PSS represents the PSS control variable;

[0140] The differential-algebraic equation of the operating power system model is:

[0141] wherein x represents the system state variable, x = [x SM , x EX , x PSS , x SYS ] T ; u represents the PSS control variable, u = [u SM , u EX , u PSS , u SYS ] T , x SYS and u SYS represent the power system state variable and algebraic variable, respectively;

[0142] S4, extracting a small disturbance stability analysis model according to the differential-algebraic equation of the operating power system model, to obtain a system small disturbance stability analysis state equation;

[0143] The specific method for obtaining the system small disturbance stability analysis state equation is:

[0144] Taylor expanding the operating power system model state equation of the generator system model, the excitation system model, the power system stabilizer PSS model and the grid-connected power system model at the operating point (x0, u0) and ignoring the high-order terms, to obtain the linearized equation at the operating point:

[0145] wherein,

[0146] Eliminating the control variable u, to obtain the system small disturbance stability analysis state equation:

[0147] wherein, the matrix A-BD -1 C is the system state matrix;

[0148] S5, constructing and initializing the system control parameter space;

[0149] According to the parameter operating range of the power system stabilizer PSS control parameter and the operating point in the system small disturbance stability analysis state equation, the system control parameter space is constructed;

[0150] S6, searching and evaluating the stability of each operating point trajectory in the specified direction;

[0151] From the operating equilibrium point, the eigenvalues of the system state matrix are calculated along the current parameter defined direction, and the small disturbance stability is analyzed according to the distribution of the dominant eigenvalue in the complex plane, which specifically includes:

[0152] S6.1, in the selected control parameter space, adjusting the corresponding control parameter from the current stable operating point along the defined direction by the current step size to obtain a new set of equilibrium points;

[0153] S6.2, calculate the eigenvalues of the system state matrix of the equilibrium point, and if the real part of the dominant eigenvalue is negative, continue to execute S6.1; otherwise, go to S6.3;

[0154] S6.3, in response to the control parameter meeting the convergence accuracy, record the current operating point as the boundary point of the control parameter stability domain in the current search direction; otherwise, back to the previous operating point and reduce the step size to 1 / 4 of the current step size, and return to S6.1;

[0155] S7, adjust the search direction of the control parameter to determine the boundary set of the control parameter stability domain;

[0156] After the current control parameter search direction is completed or has met the jump to the current step in S6.3, the search direction is changed, and S6 is executed again until each direction of the selected control parameter space is traversed, and the control parameter stability domain boundary set meeting the accuracy requirement is obtained, that is, the power system stabilizer control parameter stability boundary including the generator, excitation, and grid-connected system is drawn, and the power system stabilizer control parameter stability domain is obtained;

[0157] Taking a single-machine infinite system with an additional power system stabilizer as an example, the influence of the PSS control parameter on the system stability is analyzed, and the control parameter stability boundary is depicted. The stability boundary and stability domain in the control parameter space of the lead-lag element time constant T1 and T2 are shown in FIG. 3. In FIG. 3, the curve is the control parameter critical stability boundary, and the upper control parameter combination is in a critical stable state. The dark area in the upper left of the curve is the control parameter stability domain, and the light area is the unstable domain. Taking the stable operating point (T1 = 0.6, T2 = 0.6), the critical operating point (T1 = 0.6, T2 = 0.2415), and the unstable operating point (T1 = 0.6, T2 = 0.1) in FIG. 3 as examples, time domain simulation comparison and verification are performed, as shown in FIGS. 4 and 5. The system is disturbed at 5s, and when the control parameter is close to the critical stability boundary, the generator speed and the generator power both show low-frequency oscillation phenomena with equal amplitude. For the two control parameter groups (T1 = 0.6, T2 = 0.6) and (T1 = 0.6, T2 = 0.1), the system shows oscillation convergence and oscillation divergence trends, respectively, which can illustrate that the control parameter stability domain depicted based on the method has good applicability.

[0158] The beneficial effects of the embodiments of the present disclosure are:

[0159] The embodiment of the disclosure provides a generator power system stabilizer control parameter stability domain determination method, a joint stability analysis model considering the generator, excitation, power system stabilizer and grid-connected system is established, the system small disturbance stability is effectively evaluated based on the Lyapunov stability theory, and comparison and verification can be carried out through time sequence simulation; meanwhile, based on the stability evaluation method, the control parameter space is searched, the stability boundary of the power system stabilizer control parameter can be described, the stability margin of the current operation state and the control parameter is directly reflected, and the method has practical significance.

Claims

1. A method for determining the stability domain of a generator power system stabilizer control parameter, comprising the following steps: S1, obtaining the parameters of a generator, an excitation system, a power system stabilizer (PSS) and a grid-connected power system; S2, taking a single-machine infinite-bus system, determining the system state variables x, control variables and intermediate variables u according to the parameters of the grid-connected power system, and initializing the generator, the excitation system, the power system stabilizer (PSS) and the grid-connected power system according to the steady-state calculation results of the system; S3, obtaining an operating power system model, and establishing the differential algebraic equations of the operating power system model; S4, extracting a small disturbance stability analysis model according to the differential algebraic equations of the operating power system model, and obtaining the system small disturbance stability analysis state equation; S5, constructing and initializing the system control parameter space; S6, searching and evaluating the trajectory stability of each operating point in a specified direction; S7, adjusting the search direction of the control parameter, and determining the boundary set of the control parameter stability domain.

2. The generator power system stabilizer control parameter stability region determination method as claimed in claim 1, wherein, The parameters in S1 specifically include the operating parameters and control parameters of the generator, the operating and control parameters of the excitation system, the operating and control parameters of the power system stabilizer (PSS), and the topology structure, control parameters and boundary conditions of the grid-connected power system, wherein the topology structure, control parameters and boundary conditions of the grid-connected power system include the load position and type.

3. The generator power system stabilizer control parameter stability region determination method as claimed in claim 1, wherein, The specific method of S2 is as follows: taking a single-machine infinite-bus system, determining the system state variables x, control variables and intermediate variables u according to the topology structure, load position and type of the grid-connected power system, and initializing the generator, the excitation system, the power system stabilizer (PSS) and the grid-connected power system according to the steady-state calculation results of the system.

4. The generator power system stabilizer control parameter stability region determination method as claimed in claim 1, wherein, The operation power system model described in S3 includes a generator system model, an excitation system model, a power system stabilizer (PSS) model, and a grid-connected power system model in the form of differential algebraic equations; the generator system model is represented as: where x SM represents the generator state variable, u SM represents the generator control variable, denotes the derivative of the generator state variable with respect to time t, f SM and g SM denote functions with respect to x SM and u SM respectively; The excitation system model is represented under the condition of neglecting limits as: where x EX represents an excitation state variable, u EX represents an excitation control variable, denotes the derivative of the excitation state variable with respect to time t, f EX and g EX denote functions with respect to x EX and u EX , respectively; The power system stabilizer PSS model is expressed under the condition of ignoring limits as: where x PSS represents the PSS state variable, u PSS represents the PSS control variable, denotes the derivative of the PSS state variable with respect to time t, f PSS and g PSS denote functions with respect to x PSS and u PSS respectively; The differential-algebraic equations of the operating power system model are: where x denotes the system state variable, denotes the derivative of the system state variable with respect to time t, x = [x SM , x EX , x PSS , x SYS ] T ; u denotes the PSS control variable, u = [u SM , u EX , u PSS , u SYS ] T , x SYS and u SYS denote the power system state variable and algebraic variable, respectively, and f and g denote functions with respect to x and u, respectively.

5. The generator power system stabilizer control parameter stability region determination method as claimed in claim 1, wherein, The specific method of obtaining the system small disturbance stability analysis state equation in S4 is as follows: The Taylor expansion of the operating power system model state equation of the generator system model, the excitation system model, the power system stabilizer (PSS) model and the grid-connected power system model at the operating point (x0, u0) is carried out and the high-order terms are ignored, to obtain the linearized equation at the operating point: wherein Δx, Δu are respectively the incremental form of the time differential of the system state variable, the incremental form of the system state variable and the incremental form of the system control variable, Eliminating the control variable u, the small perturbation stability analysis state equation of the system is obtained: where the matrix A - BD -1 C is the system state matrix.

6. The generator power system stabilizer control parameter stability region determination method as claimed in claim 1, wherein, The specific method of S5 is as follows: constructing the system control parameter space according to the parameter operating range of the power system stabilizer (PSS) control parameter and the operating point in the system small disturbance stability analysis state equation.

7. The generator power system stabilizer control parameter stability region determination method as claimed in claim 1, wherein, The specific method of S6 is as follows: starting from the operating equilibrium point, calculating the eigenvalues of the system state matrix along the specified direction of the current parameters at the current step length, and analyzing the small disturbance stability according to the distribution of the dominant eigenvalues in the complex plane, specifically including: S6.1, starting from the current stable operating point along the specified direction in the selected control parameter space and adjusting the corresponding control parameter at the current step length to obtain a new set of equilibrium points; S6.2, calculating the eigenvalues of the system state matrix at the equilibrium point, and in response to the dominant eigenvalue real part being negative, continuing to execute S6.1; otherwise, turning to S6.3; S6.3, in response to the control parameter meeting the convergence precision, recording the current operating point as the boundary point of the control parameter stability domain in the current search direction; otherwise, backtracking to the previous operating point and reducing the step length to 1 / 4 of the current step length, and returning to S6.

1.

8. The generator power system stabilizer control parameter stability region determination method according to claim 7, wherein, The specific method of S7 is: after the current control parameter search direction is completed or has met S6.3 and jumps to the current step, the search direction is changed, S6 is executed again until each direction of the selected control parameter space is traversed, a control parameter stability boundary set meeting the accuracy requirement is obtained, and the power system stabilizer control parameter stability boundary including the generator, the excitation and the grid-connected system is drawn, and the power system stabilizer control parameter stability domain is obtained.

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