CN-120127644-B - Novel power system static synchronization stable security domain quick solving method and system

CN120127644BCN 120127644 BCN120127644 BCN 120127644BCN-120127644-B

Abstract

The invention belongs to the field of power system synchronization stability evaluation and calculation, in particular relates to a novel power system static synchronization stability security domain quick solving method and system, and aims to solve the problems that static synchronization stability criteria are difficult to determine and a static synchronization security domain needs to be constructed. The method comprises the steps of obtaining steady-state operation data of the power system as input data, calculating equivalent impedance of a power grid based on the input data, further obtaining an attenuation coefficient of a state of the power system, and calculating a static synchronous steady-state security domain of the power system by adopting a prediction correction method in combination with the attenuation coefficient. The method can accurately quantify the static synchronous stability margin of the system, solves the safety domain by the prediction correction method, effectively eliminates the influence of solving accuracy generated by the concave plane, can obviously improve the solving speed, reduces the calculating time and solves the more accurate safety domain.

Inventors

ZHANG HENGXU
MA RUICONG

Assignees

山东大学

Dates

Publication Date: 20260508
Application Date: 20250326

Claims (10)

1. The novel method for rapidly solving the static synchronous stable security domain of the power system is characterized by comprising the following steps of: Step S1, acquiring steady-state operation data of a power system as input data, calculating equivalent impedance of a power grid based on the input data, and further obtaining an attenuation coefficient of a state of the power system, wherein the steady-state operation data comprises voltage, current and power of each node; s2, calculating a static synchronous stable security domain of the power system by adopting a prediction correction method in combination with the attenuation coefficient; The method for calculating the static synchronous stable security domain of the power system by adopting the prediction correction method comprises the following steps: S31, obtaining a single-direction power conversion direction boundary point of a node a in the power system, and calculating to obtain a single-direction power conversion direction boundary point set N s, as a first set; s32, let k=1, d=1, regard the operation solution of any single direction power transformation direction boundary point in the first set as the searching start point, regard said first set as searching end point except searching start point sequentially other boundary points; S33, calculating a predictive solution according to a predictive solution solving method based on the value of the searching starting point and the value of the searching ending point; S34, calculating a correction direction by combining the prediction solution; s35, combining the prediction solution and the correction direction, constructing a critical point search model, solving the critical point search model, and further obtaining a correction solution; S36, obtaining whether elements in the correction solution are smaller than 0, if yes, completing the search of the security domain boundary between the search starting point and the search ending point, and enabling d=d+1 to jump to S37, otherwise, enabling k=k+1 to jump to S34, wherein d represents the number of newly added sets; S37, adding the correction solution into a new set N s,d to serve as a second set, judging whether the first set is traversed to the boundary points of P M-1 0 and P M 0 , if M is the number of the generator nodes, jumping to S38, otherwise jumping to S34; S38, gradually expanding the second set to serve as a searching starting point and a searching end point, wherein the second set is a new set which is piled into a correction solution in sequence; S39, based on the redetermined searching starting point and searching end point, executing S33-S35 to obtain a correction solution, obtaining whether elements in the correction solution exist in a condition of less than 0, if so, completing the searching of the safe domain boundary between the searching starting point and the searching end point, and jumping to S40; and S40, judging whether the last item in the second set is traversed, if so, connecting all boundary points to form a safety domain boundary, otherwise, returning to the step S38 until the last item in the second set is traversed, and not generating a new set.
2. The novel power system static synchronization stable security domain quick solving method according to claim 1, wherein the equivalent impedance is: ; in the formula, To balance the node set voltage, U G,i is the voltage phasor of generator node i, B ik is the ith row and kth column elements in matrix B, and U G,k is the voltage phasor of generator node k.
3. The novel power system static synchronization stable security domain quick solving method according to claim 2, wherein an equivalent transfer function is calculated according to the equivalent impedance, and the equivalent transfer function is: ; Where K(s) is an equivalent transfer function, E is an identity matrix, Y inv is a converter output impedance matrix, and Z g,i is an equivalent impedance.
4. The method for quickly solving the static synchronous stable security domain of the novel power system according to claim 1, wherein the attenuation coefficient is calculated by the following steps: Step S11, a node voltage equation is constructed according to the node type of the power system and the input data, wherein the node type comprises a generator set node, a contact node and a load node; step S12, constructing a node power equation; Step S13, combining the node voltage equation and the node power equation to acquire the relation between the node voltage and the current of the generator; S14, selecting a balance node as an equivalent infinite power grid unit, and calculating equivalent impedance according to the relation between the voltage and the current of the generator node; And S15, calculating an attenuation coefficient by combining the equivalent impedance.
5. The method for quickly solving a static synchronous stable security domain of a novel power system according to claim 4, wherein the attenuation coefficient is: ; ; Where K(s) is the equivalent transfer function, p ki is the modulus of the remainder, res [ K(s), p i ] is the remainder at p i .
6. The method for quickly solving the static synchronous stable security domain of the novel power system according to claim 1, wherein the method for calculating the predictive solution is as follows: ; ; Wherein: the method comprises the steps of representing a prediction solution obtained by the kth iterative computation between a direction and a+1 direction, wherein k is the iterative computation times, and d k is the prediction step length of the kth step; boundary points representing a single change in direction a; a boundary point representing a single change in a+1 direction; Representing a predictive solution obtained by the k-1 th iterative calculation between the a direction and the a+1 direction; Defining an equivalent coefficient h i,j,q to reflect the influence of the active power variation of the node i and the node j on the voltage amplitude of the node q, namely: ; where i and j are digital variables, For a pair of Equivalent coefficient of node analysis, i Is that J is Q is , Representing the variation of the i node active power, And the variation of the active power of the j node is represented.
7. The method for quickly solving static synchronous stable security domain of novel power system according to claim 1, wherein the correction direction is calculated The method comprises the following steps: ; Wherein: for the predictive solution obtained by the kth calculation, The model value of the predictive solution obtained by the kth calculation is obtained.
8. The novel power system static synchronization stable security domain quick solving method according to claim 1, wherein the critical point search model is as follows: ; Wherein x represents a node voltage vector of the system, y represents a power vector injected by the system, and f (x, y) is an alternating current system tide equation; And The upper limit and the lower limit of the voltage amplitude of the node i are respectively; And The upper limit and the lower limit of the active power value of the node i which are allowed to be changed are respectively; And The reactive power value is respectively the upper limit and the lower limit of the reactive power value of the node i, N a is the node set of the photovoltaic system, beta a ref is the maximum value of the attenuation coefficient allowed under the condition of meeting the stability, and sgn () is a sign function.
9. The method for quickly solving static synchronous stable security domain of novel power system according to claim 1, wherein the solution is corrected The calculation method comprises the following steps: ; in the formula, The correction step size of the kth step is obtained.
10. The novel power system static synchronous stable security domain quick solving system is based on the novel power system static synchronous stable security domain quick solving method according to any one of claims 1-9, and is characterized by comprising a static synchronous stable margin quantizing module and a static synchronous stable security domain quick solving module; The static synchronous stability margin quantization module is configured to acquire steady-state operation data of the power system as input data, calculate equivalent impedance of the power grid based on the input data, and further obtain an attenuation coefficient of a state of the power system; the static synchronous stable security domain rapid solving module is configured to calculate a static synchronous stable security domain of the power system by adopting a prediction correction method in combination with the attenuation coefficient; The method for calculating the static synchronous stable security domain of the power system by adopting the prediction correction method comprises the following steps: S31, obtaining a single-direction power conversion direction boundary point of a node a in the power system, and calculating to obtain a single-direction power conversion direction boundary point set N s, as a first set; s32, let k=1, d=1, regard the operation solution of any single direction power transformation direction boundary point in the first set as the searching start point, regard said first set as searching end point except searching start point sequentially other boundary points; S33, calculating a predictive solution according to a predictive solution solving method based on the value of the searching starting point and the value of the searching ending point; S34, calculating a correction direction by combining the prediction solution; s35, combining the prediction solution and the correction direction, constructing a critical point search model, solving the critical point search model, and further obtaining a correction solution; S36, obtaining whether elements in the correction solution are smaller than 0, if yes, completing the search of the security domain boundary between the search starting point and the search ending point, and enabling d=d+1 to jump to S37, otherwise, enabling k=k+1 to jump to S34, wherein d represents the number of newly added sets; S37, adding the correction solution into a new set N s,d to serve as a second set, judging whether the first set is traversed to the boundary points of P M-1 0 and P M 0 , if M is the number of the generator nodes, jumping to S38, otherwise jumping to S34; S38, gradually expanding the second set to serve as a searching starting point and a searching end point, wherein the second set is a new set which is piled into a correction solution in sequence; S39, based on the redetermined searching starting point and searching end point, executing S33-S35 to obtain a correction solution, obtaining whether elements in the correction solution exist in a condition of less than 0, if so, completing the searching of the safe domain boundary between the searching starting point and the searching end point, and jumping to S40; and S40, judging whether the last item in the second set is traversed, if so, connecting all boundary points to form a safety domain boundary, otherwise, returning to the step S38 until the last item in the second set is traversed, and not generating a new set.

Description

Novel power system static synchronization stable security domain quick solving method and system Technical Field The invention belongs to the field of power system synchronous stability assessment and calculation, and particularly relates to a novel power system static synchronous stability security domain quick solving method and system. Background In recent years, with the development of new photovoltaic energy power generation technology, the distributed photovoltaic duty ratio in a power distribution network is rapidly improved, the dynamic behavior is more complex, the static synchronous instability risk of the system is increased, and the utilization rate of new energy is influenced. The impedance analysis method can effectively evaluate the static synchronous stability characteristics of the new energy power generation system, but the stability of the analysis system of the impedance analysis method has two difficulties, namely, the determination of a reference system of a parallel system of multiple grid-connected converters, and the selection of a stability criterion, and the further expansion of the stability criterion of the impedance analysis. The existing research carries out detailed analysis on factors influencing static synchronous stability, and the comprehensive expression mainly has three points: The system is characterized in that (1) the static synchronous stability of the system is influenced by voltage, when voltage sag occurs, the output power of the grid-connected converter is suddenly reduced, the system is easy to synchronously unstably, 2) the static synchronous stability of the system is influenced by the impedance of a power grid, after the grid-connected converter is connected to the system, the higher impedance value of the power grid can cause the overall equivalent damping of the system to be smaller, even negative damping is presented, and low-frequency oscillation is caused, and 3) the static synchronous stability of the system is influenced by the control mode and parameters of the grid-connected converter. In the power distribution network, the impedance distribution of the system, the grid-connected converter mode control mode and parameters are determined in engineering application, so that the static synchronous stability of the system is mainly influenced by voltage factors, the distribution of power flow in the system is considered to influence the voltage at grid-connected points of the grid-connected converter, and further influence the static synchronous stability of the system, and therefore, a photovoltaic power distribution network safety domain meeting the static synchronous stability constraint condition and capable of being quickly and reliably solved is necessarily constructed, and important guidance is provided for power distribution and safe and stable operation of the power distribution network. Disclosure of Invention In order to solve the above problems in the prior art, that is, the problem that the static synchronization stability criterion in the prior art is difficult to determine and the static synchronization security domain needs to be constructed, the first aspect of the present invention provides a novel method for rapidly solving the static synchronization stability security domain of an electric power system, which comprises the following steps: Step S1, acquiring steady-state operation data of a power system as input data, calculating equivalent impedance of a power grid based on the input data, and further obtaining an attenuation coefficient of a state of the power system, wherein the steady-state operation data comprises voltage, current and power of each node; the attenuation coefficient is calculated by the following steps: Step S11, a node voltage equation is constructed according to the node type of the power system and the input data, wherein the node type comprises a generator set node, a contact node and a load node; step S12, constructing a node power equation; Step S13, combining the node voltage equation and the node power equation to acquire the relation between the node voltage and the current of the generator; S14, selecting a balance node as an equivalent infinite power grid unit, and calculating equivalent impedance according to the relation between the voltage and the current of the generator node; step S15, calculating an attenuation coefficient by combining the equivalent impedance; and step S2, calculating a static synchronous stable security domain of the power system by adopting a prediction correction method in combination with the attenuation coefficient. In some preferred embodiments, the equivalent impedance is: ; in the formula, To balance the node set voltage, U G,i is the voltage phasor of generator node i, B ik is the ith row and kth column elements in matrix B, and U G,k is the voltage phasor of generator node k. In some preferred embodiments, an equivalent transfer function is calculated from the equivale