Power electronic power system voltage-dominated cascading failure path searching method

Abstract

The invention relates to a power electronic power system voltage-dominated cascading fault path searching method, which can reflect the evolution process of a power system fault more completely by constructing a voltage response event-power grid multilayer coupling network, calculating the correlation weight of a voltage response event and identifying a subsequent voltage response event. According to the method, the occurrence sequence of voltage response events is identified, and the path of the voltage-dominated cascading failure in the power electronic power system is judged in series, so that the path search problem of the voltage-dominated cascading failure in the system is solved, and technical support is better provided for operation and maintenance of the power electronic power system. Moreover, the cascading failure path searching method suitable for the voltage-dominated cascading failure is provided, the path identification and judgment of the voltage-dominated cascading failure in the power electronic power system are more accurate, and the method has good technical implementation applicability and effectiveness.

Description

Technical Field

[0001] The present invention relates to the technical field of power system protection and control, and in particular to a method for searching voltage-dominant cascading fault paths in a power electronic power system. Background Art

[0002] The development and application of new energy has become an important driving force for the transformation of the power industry. Since new energy power generation has the characteristics of high distribution concentration and reverse distribution with the load center, the DC transmission system has become one of the main means to transmit the electric energy of the new energy station to the load center. The DC transmission system includes conventional DC transmission system and flexible DC transmission system. Both new energy and DC transmission rely on power electronic equipment to achieve grid-connected operation, so the power electronic power system continues to develop. However, due to the high sensitivity and strong coupling of power electronic equipment, the cascading failures in the power electronic power system are more complicated and the risks are increasing.

[0003] In traditional power systems, power system cascading failures are divided into three types according to the causes of cascading failures: overload-dominated, structure-dominated, and coordination-dominated. Overload-dominated cascading failures are the process in which a line trips due to a fault or overload, causing the power grid flow to be redistributed, and causing other lines to trip overload one after another. Structure-dominated cascading failures refer to the process in which the key interconnection lines or important nodes of the power grid are accidentally cut off or the decoupling device is prematurely operated, resulting in significant damage to the topological structure of the power grid. Coordination-dominated cascading failures are the fault deterioration process caused by unreasonable setting values ​​of secondary devices such as relay protection, low equipment reliability, and hidden faults. From a methodological perspective, the research on cascading failures is mainly divided into two categories. The first category analyzes system safety from the overall characteristics, mainly including complex network theory and self-organized criticality theory. The second category focuses on the restoration and path search of the cascading failure process, mainly including pattern search theory. Complex network theory evaluates the structural characteristics and potential vulnerabilities of the power system through graph theory features such as degree distribution, shortest path, average distance, and clustering coefficient, and effectively identifies key nodes and vulnerable lines. The self-organized criticality theory holds that the system spontaneously reaches a critical state under certain conditions, and small disturbances can trigger large-scale chain reactions, mainly explaining the mechanism of cascading failures from a macro perspective. The pattern search theory establishes a fault propagation model based on the physical characteristics of the power system, simulates the power flow transfer and equipment overload after the fault, and studies the development process of large power outages from the perspective of cascading failure sequences.

[0004] However, in the power electronic power system, there is a deep coupling between new energy stations, between multiple DC transmission systems, and between new energy and DC transmission systems. Due to the fragility and controlled characteristics of power electronic equipment, AC power grid faults may cause control switching, commutation failure, or even lockout or disconnection of power electronic equipment. After a power grid fault, the output characteristics of power electronic equipment continue to change, resulting in continuous changes in the grid voltage. The voltage change may also cause changes in the output characteristics of other power electronic equipment, causing the fault to spread within or across regions within the electromagnetic transient time scale. A chain failure with obvious voltage-dominant characteristics is presented in the power electronic power system. The chain evolution of faults is no longer caused only by structural damage, power flow transfer, or incorrect protection control. The continuous change of grid voltage becomes the cause of the chain evolution of faults. The generation mechanism and manifestation of voltage-dominant chain failures are different from traditional chain failures. The existing chain failure research methods are dedicated to characterizing the relationship between changes in grid power flow distribution and chain failures under line overload and relay protection action. They cannot reflect the changes in the operating status of equipment during continuous voltage changes and are difficult to apply to voltage-dominant chain failures.

[0005] To sum up, how to consider the process of voltage coupling between power electronic equipment and between equipment and the power grid, fully analyze the evolution mechanism of voltage-dominated cascading failures from the voltage perspective, and propose a path search method for voltage-dominated cascading failures has become an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0006] In view of the deficiencies of the above-mentioned prior art, the present invention provides a method for searching the path of voltage-dominant cascading failures in a power electronic power system. The method constructs a voltage response event-grid multilayer coupling network, calculates the voltage response event association weights, and identifies subsequent voltage response events, thereby solving the path search problem of voltage-dominant cascading failures in the system, so as to better provide technical support for the operation and maintenance of the power electronic power system.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A method for searching a voltage-dominant cascading fault path in a power electronic power system comprises the following steps:

[0009] S1. Collect current working parameters of power electronic equipment in the power electronic system and determine the action status of each voltage response event in the current power system;

[0010] S2. Determine the association process of each voltage response event in the power system and its corresponding correlation coefficient according to the action state of the voltage response event;

[0011] S3. According to the association process of the voltage response event and its correlation coefficient, a voltage response event-grid multilayer coupling network is constructed; the voltage response event-grid multilayer coupling network is used to represent the association relationship between the grid node and the voltage response event and the weight value of each association relationship;

[0012] S4, establishing a random walk model based on the voltage response event-grid multi-layer coupling network element path;

[0013] S5. Using the Markov chain Monte Carlo method, a random walk model based on the voltage response event-grid multi-layer coupling network element path is searched and solved to determine the order of occurrence of each voltage response event in the power system;

[0014] S6. Determine the path of the voltage-dominant cascading fault in the power electronic power system in series according to the order in which the voltage response events occur, and complete the fault path search.

[0015] Specifically, in step S1, the action state of the voltage response event includes start, trigger, hold, and stop. The action state of any voltage response event i is determined in the following manner:

[0016]

[0017] In the formula, Sta i Indicates the action state of voltage response event i; cU i and cT i are the voltage state variable and time state variable of voltage response event i respectively;

[0018] Among them, the voltage state variable cU of the voltage response event i i and the time state variable cT i It is determined as follows:

[0019]

[0020] Where U i is the grid-connected node voltage of the power electronic equipment corresponding to the voltage response event; C UThi represents the voltage range of voltage response event i; T Thi represents the action time of voltage response event i; t cUi represents the change time of the voltage state variable of voltage response event i; t is the current time.

[0021] Specifically, in step S2, the association process of the voltage response event includes the association of the triggering or stopping of the voltage response event with the power exchange, the association of the power exchange with the voltage change, the association of the voltage change with the start or maintenance of the voltage response event, and the association of the start or maintenance of the voltage response event with the triggering or termination;

[0022] The correlation coefficients corresponding to the voltage response event association process include the correlation coefficient between the triggering or termination of voltage response event i and the power exchange of grid node p, the correlation coefficient between the power exchange of grid node p and the voltage change of grid node q, the correlation coefficient between the voltage change of grid node q and the start or maintenance of voltage response event j, and the correlation coefficient between the start or maintenance and triggering or termination of voltage response event j.

[0023] Specifically, in step S2, the correlation coefficient of the voltage response event i triggering or terminating the power exchange with the grid node p is calculated as follows:

[0024]

[0025] The correlation coefficient between the power exchange at the grid node p and the voltage change at the grid node q is calculated as follows:

[0026]

[0027] The correlation coefficient between the voltage change of grid node q and the start or maintenance of voltage response event j is calculated as follows:

[0028]

[0029] The correlation coefficient of the voltage response event j starting or holding and triggering or aborting is calculated as follows:

[0030]

[0031] Among them, E p represents the voltage response event set of the power electronic equipment at node p; α ip =0 means that the voltage response event i has no correlation with the power of the grid node p; α ip =1 indicates that the voltage response event i is directly related to the power of the grid node p; ΔU q is the voltage change of the grid node q; ΔP p , ΔQ p They represent the changes in active and reactive power exchange between the power electronic equipment and the grid node p; k P and k Q They represent the weights of active voltage sensitivity and reactive voltage sensitivity respectively; c represents the correlation coefficient bias coefficient; τ j It represents the remaining action time of voltage response event j, which is the difference between the event action time and the current time.

[0032] Specifically, in step S3, a voltage response event-grid multi-layer coupling network is established in the following manner:

[0033] CN=(N∪E,CX ,W X );

[0034] Where N = {n 1 ,n 2 ,…,n k} represents the set of grid nodes to which the power electronic equipment is connected, k is the number of grid nodes to which the power electronic equipment is connected; E = {e 1 ,e 2 ,…,e m-1 ,e m} represents the voltage response event set, m is the number of voltage response events; W X Represents the weight value matrix of the multi-layer coupling network association relationship;

[0035] The voltage response event-grid multilayer coupling network includes four single-layer association networks: a grid node association network, a voltage response event association network, a voltage response event and grid node directed association network, and a grid node and voltage response event directed association network. X is a set of multi-layer association relationships between voltage response events and power grids, and C X =C NN ∪C EE ∪C NE ∪C EN , where C NN is the grid node association network L NN The set of association relationships, C EE is the voltage response event association network L EE The set of association relationships, C EN is a directed association network L between voltage response events and power grid nodes EN The set of association relationships, C NE is a directed association network L between power grid nodes and voltage response events NE The set of association relationships is determined as follows:

[0036] Grid node association network L NN The association relationship set C NN is the set of all N(p)→N(q) association relationships, where N(p)→N(q) represents the association relationship between grid node p and grid node q, and N(p) and N(q) represent grid node p and grid node q respectively;

[0037] Voltage response event association network L EE The set of association relations C EE is the set of all E(i)→E(j) association relationships, where E(i)→E(j) represents the association relationship between voltage response event i and voltage response event j, and E(i) and E(j) represent voltage response event i and voltage response event j respectively;

[0038] The voltage response event and the directed association network L of the power grid nodes EN The set of association relations C EN is the set of all E(i)→N(p) association relationships, where E(i)→N(p) represents the directed association relationship between voltage response event i and grid node p;

[0039] Directed association network L between power grid nodes and voltage response events NE The set of association relations C NE It is a set of all N(q)→E(j) association relationships, where N(q)→E(j) represents a directed association relationship between a grid node q and a voltage response event j.

[0040] Specifically, the grid node association network L NN , voltage response event association network L EE , voltage response events and grid nodes directed association network L EN , the directed association network L between power grid nodes and voltage response events NE Respectively expressed as:

[0041] L NN =(N,C NN ,W NN );

[0042] L EE =(E,C EE ,W EE );

[0043] L EN =(E∪N,C EN ,W EN );

[0044] L NE =(N∪E,C NE ,W NE );

[0045] Where W NN is the weight value matrix of the association relationship between power grid nodes; W EE is the weight value matrix of the unknown correlation relationship of the voltage response event; W EN is the weight value matrix of the directed association relationship between voltage response events and power grid nodes; W NE is the weight value matrix of the directed association relationship between the power grid nodes and the voltage response events; the multi-layer coupling network association relationship weight value matrix W X By W NN , W EN , W NE , W EE The composition is expressed as:

[0046]

[0047] Specifically, the weight value matrix W of the association relationship between the grid nodes is NN , the weight value matrix W of the directed association relationship between voltage response events and power grid nodes EN , the weight matrix W of the directed association relationship between grid nodes and voltage response events NE , the weight value matrix W of the unknown correlation relationship of the voltage response event EE The weight values ​​in are determined as follows:

[0048]

[0049] Where W NN (p,q)∈W NN The weight value representing the association relationship between grid node p and grid node q, β pq is the correlation coefficient between the power exchange of grid node p and the voltage change of grid node q; W EN (i,p)∈W EN represents the weight value of the directed association relationship between voltage response event i and grid node p, α ip is the correlation coefficient of the voltage response event i triggering or terminating the power exchange with the grid node p; W NE (q,j)∈W NE The weight value of the directed association relationship between the grid node q and the voltage response event j, θ qj is the correlation coefficient between the voltage change of grid node q and the start or maintenance of voltage response event j; γ j W is the correlation coefficient between starting or maintaining and triggering or stopping of voltage response event j; EE (e i )∈W EE W represents the weight value vector of the unknown correlation between voltage response event i and other voltage response events in the power system; EE (e i ) p (e i ,e j ) represents the weight value of the association relationship between voltage response event j and voltage response event i after any voltage response event i occurs. It is an unknown quantity and needs to be determined by solving.

[0050] Specifically, in step S4, the random walk model based on the voltage response event-grid multi-layer coupling network element path is established in the following manner:

[0051]

[0052] Where, CN is the voltage response event-grid multilayer coupling network; MP is the random walk element path; v init is the initial node of the walk; W path (v init ) represents the initial node v init Starting from, the weight value matrix of different walking paths in the meta-path MP; e and n represent the voltage response event node and the power grid node in the voltage response event-power grid multi-layer coupling network respectively.

[0053] Specifically, in step S5, the method of performing a walk search and solving the random walk model based on the voltage response event-grid multi-layer coupling network element path is:

[0054] The voltage response event with the action state as the start is the initial node of the particle random walk. According to the random walk model of the voltage response event-grid multi-layer coupling network meta-path, the Markov chain Monte Carlo method is used to randomly select the lower-level nodes of each walk according to the meta-path e→n→n→e, and the corresponding walk path weight is calculated, thereby traversing to obtain the current initial node v init With other different voltage response events as the end point of the wandering path v end The walking path weight is used as the current initial node v init The weight value of the association relationship between the voltage response event node and other voltage response events is calculated, and the order of occurrence of each voltage response event in the power system is determined according to the order of the weight values ​​of the association relationship from large to small.

[0055] Specifically, the step S5 is as follows:

[0056] S501: according to the action state of each voltage response event in the current power system determined in step S1, the action state Sta i is started, and the action time is T Thi The shortest voltage response event is the initial node v of the random walk of the particle in the current walk path. init ;

[0057] S502, according to the action status of each voltage response event in the current power system, determine the correlation process of each current voltage response event in the power system and its corresponding correlation coefficient, and obtain the current correlation relationship weight value matrix of the voltage response event-grid multi-layer coupling network;

[0058] S503, using the current initial node v init As the starting point, according to the random walk model of the voltage response event-grid multi-layer coupling network meta-path, according to the meta-path MP=e→n→n→e, the Markov chain Monte Carlo method is used to randomly select the lower-level nodes of each walk and calculate the corresponding walk path weight:

[0059] w p (v init ,v end )=w(v init |v n1 )·w(v n1 |v n2 )·w(v n2 |v end );

[0060] In the formula, w p (v init ,v end ) is from the initial node v init Start from the path MP and travel to the end point v of the travel path end The wandering path weight of the voltage response event node is the unknown quantity to be solved, which represents the voltage response from the initial node v init Start, walk along the meta-path e→n→n→e and stop at v end Stop, its wandering path is v init →v n1 →v n2 →v end The walking path weight of v n1 、v n2 represents the two grid nodes passed in the wandering path; w(v init |v n1 ) represents the initial node v init Walk to the first grid node v in the meta-path n1 The walking path weight, w(v n1 |v n2 ) represents the first grid node v in the meta-path n1 Walk to the second grid node v n2 The walking path weight, w(v n2 |v end ) represents the second grid node v in the meta-path n2 Walk to the end of the walk path v end The wandering path weights are all known quantities that can be calculated and determined through the weight value matrix of the correlation relationship between the voltage response event and the multi-layer coupling network of the power grid;

[0061] This traverses to obtain the current initial node v init With other different voltage response events as the end point of the wandering path v end The walking path weight is used as the current initial node v init The weight value of the association relationship between the voltage response event node and other voltage response events;

[0062] S504: Determine the current initial node v initWhether the weight values ​​of the association relationship between the voltage response event node and other voltage response events are all 0; if so, it is determined to end the wandering search; otherwise, the wandering path end point v with the largest association weight value is end The corresponding voltage response event is determined as a voltage response event that occurs subsequently;

[0063] S505, taking the subsequent voltage response event as a new initial node, re-collecting the current working parameters of the power electronic equipment in the power electronic power system, re-determining the action status of each voltage response event in the current power system, and jumping back to step S502;

[0064] S506, looping through steps S502 to S505 until the wandering search is finished, and determining the order in which each voltage response event in the power system occurs.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] 1. The existing fault analysis technology of power electronic equipment only focuses on the changes in the operating state of power electronic equipment caused by voltage and the phenomenon that the operating state of power electronic equipment affects each other through voltage. The method of the present invention further combines and considers the process of voltage coupling between power electronic equipment and between equipment and power grid, and constructs a voltage response event-grid multi-layer coupling network, which can more completely reflect the evolution process of power system faults, identify the order of occurrence of voltage response events, and determine the path of voltage-dominated cascading failures in power electronic power systems in series, thereby solving the path search problem of voltage-dominated cascading failures in the system, so as to better provide technical support for the operation and maintenance of power electronic power systems.

[0067] 2. The existing technology is only applicable to the three types of chain failures of overload-dominated, structure-dominated, and coordination-dominated in the power system, and cannot be applied to the voltage-active chain failures of the power system caused by the large-scale application of power electronics. The method of the present invention proposes a chain failure path search method applicable to voltage-dominated chain failures based on the difference in the physical mechanism between voltage-dominated chain failures and overload-dominated, structure-dominated, and coordination-dominated chain failures. The method is more accurate in identifying and determining the path of voltage-dominated chain failures in power electronic power systems, and has good technical implementation applicability and effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to make the purpose, technical solution and advantages of the invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0069] Figure 1 A flow chart of a method for searching a path of voltage-dominant cascading failures in a power system;

[0070] Figure 2 It is a schematic diagram of the structure of the power system including the access of power electronic equipment;

[0071] Figure 3 This is a diagram showing the prediction result of the voltage response event association relationship of the line 14-16 fault in an embodiment of the present invention;

[0072] Figure 4 It is the grid-connected node voltage of the power electronic equipment when the line 14-16 fails in the embodiment of the present invention. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but only represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0074] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0075] The present invention provides a method for searching the path of voltage-dominant cascading failures in a power electronic power system. The method constructs a voltage response event-grid multilayer coupling network for voltage-dominant cascading failures in a power electronic power system, calculates the associated weights of voltage response events, identifies subsequent voltage response events, and searches for the path of voltage-dominant cascading failures.

[0076] Based on the above technical design ideas, the specific process of the voltage-dominant cascading fault path search method for power electronic power system of the present invention is as follows: Figure 1 As shown, the following steps are included:

[0077] S1. Collect current working parameters of power electronic equipment in the power electronic system and determine the action status of each voltage response event in the current power system;

[0078] S2. Determine the association process of each voltage response event in the power system and its corresponding correlation coefficient according to the action state of the voltage response event;

[0079] S3. According to the association process of the voltage response event and its correlation coefficient, a voltage response event-grid multilayer coupling network is constructed; the voltage response event-grid multilayer coupling network is used to represent the association relationship between the grid node and the voltage response event and the weight value of each association relationship;

[0080] S4, establishing a random walk model based on the voltage response event-grid multi-layer coupling network element path;

[0081] S5. Using the Markov chain Monte Carlo method, a random walk model based on the voltage response event-grid multi-layer coupling network element path is searched and solved to determine the order of occurrence of each voltage response event in the power system;

[0082] S6. Determine the path of the voltage-dominant cascading fault in the power electronic power system in series according to the order in which the voltage response events occur, and complete the fault path search.

[0083] In the specific implementation, the operating parameters of the power electronic equipment in the power electronic power system collected in step S1 may include parameters such as AC bus voltage, voltage duration and power exchange amount. These operating parameters are mainly used to determine the action status of each voltage response event in the current power system, and then determine the association process of each voltage response event in the power system and its corresponding correlation coefficient.

[0084] In the specific implementation, in step S1, the action state of the voltage response event includes start, trigger, hold, and stop. The action state of any voltage response event i is determined in the following manner:

[0085]

[0086] In the formula, Sta i Indicates the action state of voltage response event i; cU i and cT i are the voltage state variable and time state variable of voltage response event i respectively.

[0087] The voltage state variable and time state variable of the voltage response event i are specifically determined in the following manner:

[0088]

[0089] Where U i is the grid-connected node voltage of the power electronic equipment corresponding to the voltage response event; C UThirepresents the voltage range of voltage response event i; T Thi represents the action time of voltage response event i; t cUi represents the change time of the voltage state variable of voltage response event i; t is the current time.

[0090] According to formula (2), the voltage state variable and time state variable of the voltage response event are taken as follows: if the voltage satisfies the voltage range of the voltage response event, the voltage state variable of the voltage response event is 1, otherwise it is 0; if the duration of the voltage satisfying the voltage range reaches the action time of the voltage response event, the time state variable of the voltage response event is 1, otherwise it is 0.

[0091] In the specific implementation, in step S2, the association process of the voltage response event includes the association of the triggering or termination of the voltage response event with the power exchange, the association of the power exchange with the voltage change, the association of the voltage change with the start or maintenance of the voltage response event, and the association of the start or maintenance of the voltage response event with the triggering or termination.

[0092] Correspondingly, the correlation coefficients corresponding to the voltage response event association process include the correlation coefficient between the triggering or termination of voltage response event i and the power exchange of grid node p, the correlation coefficient between the power exchange of grid node p and the voltage change of grid node q, the correlation coefficient between the voltage change of grid node q and the start or maintenance of voltage response event j, and the correlation coefficient between the start or maintenance and triggering or termination of voltage response event j.

[0093] In the specific implementation, the correlation coefficient of the voltage response event i triggering or terminating the power exchange with the grid node p is calculated as follows:

[0094]

[0095] In the formula, E p represents the set of voltage response events of power electronic equipment at node p; α ip =0 means that the voltage response event i has no correlation with the power of the grid node p; α ip =1 indicates that the voltage response event i is directly related to the power of the grid node p.

[0096] In specific implementation, the correlation coefficient between the power exchange of the grid node p and the voltage change of the grid node q is calculated as follows:

[0097]

[0098] In the formula, ΔU q is the voltage change of the grid node q; ΔP p , ΔQ p They represent the changes in active and reactive power exchange between the power electronic equipment and the grid node p; kP and k Q They represent the weights of active voltage sensitivity and reactive voltage sensitivity respectively; c represents the correlation coefficient bias coefficient.

[0099] In a specific implementation, the correlation coefficient between the voltage change of the grid node q and the start or maintenance of the voltage response event j is calculated as follows:

[0100]

[0101] In a specific implementation, the correlation coefficient between the start or hold and the trigger or stop of the voltage response event j is calculated as follows:

[0102]

[0103] In the formula, τ j It represents the remaining action time of voltage response event j, which is the difference between the event action time and the current time.

[0104] In specific implementation, in step S3, the voltage response event-grid multi-layer coupling network is established as follows:

[0105] CN=(N∪E,C X ,W X ) (7)

[0106] Where N = {n 1 ,n 2 ,…,n k} represents the set of grid nodes to which the power electronic equipment is connected, k is the number of grid nodes to which the power electronic equipment is connected; E = {e 1 ,e 2 ,…,e m-1 ,e m} represents the voltage response event set, m is the number of voltage response events; W X Represents the weight value matrix of the multi-layer coupling network association relationship.

[0107] The established voltage response event-grid multilayer coupling network includes four single-layer association networks: grid node association network, voltage response event association network, voltage response event and grid node directed association network, and grid node and voltage response event directed association network. X is a set of multi-layer association relationships between voltage response events and power grids, and C X =C NN ∪C EE ∪C NE ∪C EN , where C NN is the grid node association network L NN The set of association relationships, C EEis the voltage response event association network L EE The set of association relationships, C EN is a directed association network L between voltage response events and power grid nodes EN The set of association relationships, C NE is a directed association network L between power grid nodes and voltage response events NE The set of association relationships is determined as follows:

[0108] Grid node association network L NN The set of association relations C NN is the set of all N(p)→N(q) association relationships, where N(p)→N(q) represents the association relationship between grid node p and grid node q, and N(p) and N(q) represent grid node p and grid node q respectively;

[0109] Voltage response event association network L EE The set of association relations C EE is the set of all E(i)→E(j) association relationships, where E(i)→E(j) represents the association relationship between voltage response event i and voltage response event j, and E(i) and E(j) represent voltage response event i and voltage response event j respectively;

[0110] The voltage response event and the directed association network L of the power grid nodes EN The set of association relations C EN is the set of all E(i)→N(p) association relationships, where E(i)→N(p) represents the directed association relationship between voltage response event i and grid node p;

[0111] Directed association network L between power grid nodes and voltage response events NE The set of association relations C NE It is a set of all N(q)→E(i) association relationships, where N(q)→E(i) represents a directed association relationship between a grid node q and a voltage response event i.

[0112] Specifically, the grid node association network L NN , voltage response event association network L EE , voltage response events and grid nodes directed association network L EN , the directed association network L between power grid nodes and voltage response events NE Respectively expressed as:

[0113] L NN =(N,C NN ,W NN ) (8)

[0114] L EE =(E,CEE ,W EE ) (9)

[0115] L EN =(E∪N,C EN ,W EN ) (10)

[0116] L NE =(N∪E,C NE ,W NE ) (11)

[0117] Where W NN is the weight value matrix of the association relationship between power grid nodes; W EE is the weight value matrix of the unknown correlation relationship of the voltage response event; W EN is the weight value matrix of the directed association relationship between voltage response events and power grid nodes; W NE It is the weight value matrix of the directed association relationship between power grid nodes and voltage response events.

[0118] Multi-layer coupling network association relationship weight matrix W X Then W NN , W EN , W NE , W EE The composition is expressed as:

[0119]

[0120] In specific implementation, the weight value matrix W of the association relationship between power grid nodes is NN , the weight value matrix W of the directed association relationship between voltage response events and power grid nodes EN , the weight matrix W of the directed association relationship between grid nodes and voltage response events NE , the weight value matrix W of the unknown correlation relationship of the voltage response event EE The weight values ​​in are determined as follows:

[0121]

[0122] Where W NN (p,q)∈W NN The weight value representing the association relationship between grid node p and grid node q, β pq is the correlation coefficient between the power exchange of grid node p and the voltage change of grid node q; W EN (i,p)∈W EN represents the weight value of the directed association relationship between voltage response event i and grid node p, α ip is the correlation coefficient of the voltage response event i triggering or terminating the power exchange with the grid node p; W NE(q,j)∈W NE The weight value of the directed association relationship between the grid node q and the voltage response event j, θ qj is the correlation coefficient between the voltage change of grid node q and the start or maintenance of voltage response event j; γ j W is the correlation coefficient between starting or maintaining and triggering or stopping of voltage response event j; EE (e i )∈W EE W represents the weight value vector of the unknown correlation between voltage response event i and other voltage response events in the power system; EE (e i ) p (e i ,e j ) represents the weight value of the association relationship between voltage response event j and voltage response event i after any voltage response event i occurs. It is an unknown quantity and needs to be determined by solving. The expression {A→B}∈C in the formula means that the association from A to B belongs to the association set C.

[0123] In specific implementation, in step S4, the random walk model based on the voltage response event-grid multi-layer coupling network element path is established in the following manner:

[0124]

[0125] Where, CN is the voltage response event-grid multilayer coupling network; MP is the random walk element path; v init is the initial node of the walk; W path (v init ) represents the initial node v init Starting from, the weight value matrix of different walking paths in the meta-path MP; e and n represent the voltage response event node and the power grid node in the voltage response event-power grid multi-layer coupling network respectively.

[0126] In specific implementation, in step S5, the method of performing a walk search and solving the random walk model based on the voltage response event-grid multi-layer coupling network element path is:

[0127] The voltage response event with the action state as the start is the initial node of the particle random walk. According to the random walk model of the voltage response event-grid multi-layer coupling network meta-path, the Markov chain Monte Carlo method is used to randomly select the lower-level nodes of each walk according to the meta-path e→n→n→e, and the corresponding walk path weight is calculated, thereby traversing to obtain the current initial node v init With other different voltage response events as the end point of the wandering path v end The walking path weight is used as the current initial node v initThe weight value of the association relationship between the voltage response event node and other voltage response events is calculated, and the order of occurrence of each voltage response event in the power system is determined according to the order of the weight values ​​of the association relationship from large to small.

[0128] Specifically, step S5 is as follows:

[0129] S501: according to the action state of each voltage response event in the current power system determined in step S1, the action state Sta i is started, and the action time is T Thi The shortest voltage response event is the initial node v of the random walk of the particle in the current walk path. init .

[0130] S502: According to the action states of the voltage response events in the current power system, the correlation process of the current voltage response events in the power system and their corresponding correlation coefficients are determined to obtain the current correlation relationship weight value matrix of the voltage response event-grid multi-layer coupling network.

[0131] S503, using the current initial node v init As the starting point, according to the random walk model of the voltage response event-grid multi-layer coupling network meta-path, according to the meta-path MP=e→n→n→e, the Markov chain Monte Carlo method is used to randomly select the lower-level nodes of each walk and calculate the corresponding walk path weight:

[0132] w p (v init ,v end )=w(v init |v n1 )·w(v n1 |v n2 )·w(v n2 |v end ) (18)

[0133] In the formula, w p (v init ,v end ) is from the initial node v init Start from the path MP and travel to the end point v of the travel path end The wandering path weight of the voltage response event node is the unknown quantity to be solved, which represents the voltage response from the initial node v init Start, walk along the meta-path e→n→n→e and stop at v end Stop, its wandering path is v init →v n1 →v n2 →v end The walking path weight of v n1 、v n2represents the two grid nodes passed in the wandering path; w(v init |v n1 ) represents the initial node v init Walk to the first grid node v in the meta-path n1 The walking path weight, w(v n1 |v n2 ) represents the first grid node v in the meta-path n1 Walk to the second grid node v n2 The walking path weight, w(v n2 |v end ) represents the second grid node v in the meta-path n2 Walk to the end of the walk path v end The wandering path weights are all known quantities that can be calculated and determined through the weight value matrix of the correlation relationship between the voltage response event and the multi-layer coupling network of the power grid.

[0134] For example, if the voltage response event of the initial node is i, and the voltage response event of the wandering path is v end The voltage response event node is j, and the two grid nodes passed in the wandering path are grid node p and grid node q respectively. Then let the weight value of the association relationship between voltage response event j and voltage response event i be w p (e x ,e i )=w p (v init ,v end ), is the unknown quantity to be solved; w(v init |v n1 ) is the weight value W of the directed association relationship between voltage response event i and grid node p EN (i,p), that is, w(v init |v n1 )=W EN (i,p);w(v n1 |v n2 ) is the weight value W of the association relationship between the power grid node p and the power grid node q NN (p,q), that is, w(v n1 |v n2 )=W NN (p,q);w(v n2 |v end ) is the weight value W of the directed association relationship between the grid node q and the voltage response event j NE (q,j), that is, w(v n2 |v end )=W NE (q,j); therefore, w(v init |v n1)、w(v init |v n1 )、w(v n1 |v n2 ) are all known quantities that can be determined by calculating the weight value matrix of the voltage response event-grid multi-layer coupling network association relationship.

[0135] This traverses to obtain the current initial node v init With other different voltage response events as the end point of the wandering path v end The walking path weight is used as the current initial node v init The weight value of the association relationship between the voltage response event node and other voltage response events.

[0136] S504: Determine the current initial node v init Whether the weight values ​​of the association relationship between the voltage response event node and other voltage response events are all 0; if so, it is determined to end the wandering search; otherwise, the wandering path end point v with the largest association weight value is end The corresponding voltage response event is determined as a voltage response event that occurs subsequently.

[0137] S505, taking the subsequent voltage response event as a new initial node, re-collecting the current working parameters of the power electronic equipment in the power electronic power system, re-determining the action status of each voltage response event in the current power system, and jumping back to step S502.

[0138] S506, looping through steps S502 to S505 until the wandering search is finished, and determining the order in which each voltage response event in the power system occurs.

[0139] In the above process, each voltage response event is determined as the initial node v of the random walk. init Based on the action states of the corresponding voltage response events, the correlation process of the current voltage response events in the power system and their corresponding correlation coefficients are determined, and the current correlation weight value matrix of the voltage response event-grid multi-layer coupling network is obtained. The current initial node v is obtained by random walking along the meta-path MP=e→n→n→e through the Markov chain Monte Carlo method. init With other different voltage response events as the end point of the wandering path v end The walking path weight is the other voltage response events and the current initial node v initThe weight value of the association relationship between the voltage response event nodes is determined; then, according to the weight value of the association relationship, a subsequent voltage response event is determined as the initial node of the new walk search, and the action state of each voltage response event, the association process of each voltage response event and its corresponding correlation coefficient are re-determined based on the new initial node, and then the current association relationship weight value matrix of the voltage response event-grid multi-layer coupling network is re-obtained to participate in the new round of random walk model solution calculation, and so on, until the end of the walk search. In this way, when the voltage response event as the initial node is re-determined in each round, the impact of the previous voltage response event on the output characteristics of the current power electronic equipment and the change of the operating state are considered by recalculation, so that the path search and identification of the chain failure with voltage-dominant characteristics in the power system is more accurate.

[0140] Example:

[0141] In order to verify the effectiveness of the present invention, Figure 2 The structural diagram of the power system with power electronic equipment connected is used as an example for analysis. Figure 2 In the embodiment shown, the flexible DC transmission system (flexible DC transmission system) is connected to the receiving end grid via nodes 35, 36, 37, 38, and 39, with transmission capacities of 1488.20MW, 1488.20MW, 957.80MW, 634.70MW, and 1514.80MW, respectively. The wind farm (WF) is equipped with direct-drive wind turbines, which are connected to the AC grid via nodes 18 and 33, with grid-connected capacities of 250.00MW and 350.00MW, respectively. The conventional DC transmission system (conventional DC transmission system) is connected to the receiving end grid via nodes 11, 15, 17, and 34, with transmission capacities of 2816.20MW, 2856.00MW, 1160.00MW, and 5996.40MW, respectively.

[0142] The voltage response events and their voltage ranges are shown in Table 1.

[0143] Table 1 Voltage response event voltage range conditions

[0144]

[0145] The conventional DC transmission system will be locked after three consecutive commutation failures within 200ms. The off-grid action time of WF and flexible DC transmission systems is calculated according to the action time of relay protection. When the WF voltage drops below 0.2pu, there is no delay in off-grid operation; when the WF voltage is between 0.2 and 0.9pu, the action time increases linearly with the voltage in the range of 625 to 2000ms. When the WF voltage is between 1.1 and 1.2pu, 1.2 and 1.25pu, 1.25 and 1.3pu, and above 1.3pu, the action time is 10s, 1s, 0.5s, and 0s, respectively. When the voltage of the flexible DC transmission system drops below 0.2pu, the off-grid action time is 150ms. The action time of the flexible DC transmission system at other voltages is the same as that of the WF. The response delay of voltage support control and high voltage ride-through of WF and flexible DC transmission systems is determined by the performance of the controller. The dynamic reactive current rise time and exit time are usually required to be less than 60ms, and 25ms, 45ms, and 45ms are selected respectively. Commutation failure usually occurs within half of the power frequency cycle after the fault occurs, and 5ms is selected as the action time of commutation failure. The power change caused by voltage support control and high voltage ride-through of WF and flexible DC transmission systems is calculated according to the change of the control reference value; after disconnection and locking occur, the power becomes 0.

[0146] This embodiment takes a three-phase short circuit fault occurring at 10ms as an example, and the fault is cleared after 140ms as a scenario. When line 14-16 fails, the search results of the chain fault path are shown in Table 2. The voltage changes of the nodes connected to the power electronic equipment are sequentially affected by the conventional DC transmission system commutation failure, WF voltage support control, flexible DC transmission system voltage support control, conventional DC transmission system commutation failure and lockout, conventional DC transmission system commutation failure, WF voltage support control, and flexible DC transmission system voltage support control, which is consistent with the chain fault path search results.

[0147] Figure 3 The voltage response event correlation relationship prediction result diagram of the line 14-16 fault in this embodiment is shown; Figure 4 The voltage of the power electronic equipment grid-connected node when the line 14 - 16 fails in this embodiment is shown. Figure 3 The association weights of the preceding voltage response events and the subsequent voltage response events are shown. Each association process with the largest weight constitutes the chain failure path shown in Table 2. Figure 4 It can be seen that the voltage change caused by the voltage response event in the cascading fault path described in Table 2 is Figure 4 The voltage variation trends obtained from the simulation are the same, which effectively illustrates the accuracy of the cascading failure path.

[0148] Table 2 Search results for the cascading failure path of line 14-16 fault

[0149]

[0150] It can be seen from this that the method for searching the path of voltage-dominant cascading failures in the power electronic power system provided by the present invention, on the basis of paying attention to the changes in the operating state of power electronic equipment caused by voltage and the mutual influence of the operating state of power electronic equipment through voltage, further combines and considers the process of voltage coupling between power electronic equipment and between equipment and power grid, and constructs a voltage response event-grid multilayer coupling network, which can more completely reflect the evolution process of power system faults, identify the order of occurrence of voltage response events, and determine the path of voltage-dominant cascading failures in the power electronic power system in series, thereby solving the path search problem of voltage-dominant cascading failures in the system, and providing better technical support for the operation and maintenance of power electronic power systems. At the same time, the method of the present invention proposes a cascading failure path search method suitable for voltage-dominant cascading failures based on the difference between the physical mechanisms of voltage-dominant cascading failures and overload-dominant, structure-dominant, and coordination-dominant cascading failures, which is more accurate in identifying and determining the path of voltage-dominant cascading failures in the power electronic power system, and has good technical implementation applicability and effectiveness.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A method for searching voltage-dominated cascading fault paths in power electronic power systems. It is characterized in that The following steps are involved: S1. Collect current working parameters of power electronic equipment in the power electronic system and determine the action status of each voltage response event in the current power system; S2. Determine the association process of each voltage response event in the power system and its corresponding correlation coefficient according to the action state of the voltage response event; S3. According to the association process of the voltage response event and its correlation coefficient, a voltage response event-grid multilayer coupling network is constructed; the voltage response event-grid multilayer coupling network is used to represent the association relationship between the grid node and the voltage response event and the weight value of each association relationship; S4, establishing a random walk model based on the voltage response event-grid multi-layer coupling network element path; S5. Using the Markov chain Monte Carlo method, a random walk model based on the voltage response event-grid multi-layer coupling network element path is searched and solved to determine the order of occurrence of each voltage response event in the power system; S6. Determine the path of the voltage-dominant cascading fault in the power electronic power system in series according to the order in which the voltage response events occur, and complete the fault path search.

2. The method for searching voltage-dominant cascading failure paths in a power electronic power system according to claim 1, It is characterized in that In step S1, the action state of the voltage response event includes start, trigger, hold, and stop. The action state of any voltage response event i is determined in the following manner: In the formula, Sta i Indicates the action state of voltage response event i; cU i and cT i are the voltage state variable and time state variable of voltage response event i respectively; Among them, the voltage state variable cU of the voltage response event i i and the time state variable cT i It is determined as follows: Where U i is the grid-connected node voltage of the power electronic equipment corresponding to the voltage response event; C UThi represents the voltage range of voltage response event i; T Thi represents the action time of voltage response event i; t cUi represents the change time of the voltage state variable of voltage response event i; t is the current time.

3. The method for searching voltage-dominant cascading failure paths in a power electronic power system according to claim 1, It is characterized in that In step S2, the association process of the voltage response event includes the association of the triggering or stopping of the voltage response event with the power exchange, the association of the power exchange with the voltage change, the association of the voltage change with the start or maintenance of the voltage response event, and the association of the start or maintenance of the voltage response event with the triggering or suspension; The correlation coefficients corresponding to the voltage response event association process include the correlation coefficient between the triggering or termination of voltage response event i and the power exchange of grid node p, the correlation coefficient between the power exchange of grid node p and the voltage change of grid node q, the correlation coefficient between the voltage change of grid node q and the start or maintenance of voltage response event j, and the correlation coefficient between the start or maintenance and triggering or termination of voltage response event j.

4. The method for searching voltage-dominant cascading failure paths in a power electronic power system according to claim 3, It is characterized in that In step S2, the correlation coefficient of the voltage response event i triggering or terminating the power exchange with the grid node p is calculated as follows: The correlation coefficient between the power exchange at the grid node p and the voltage change at the grid node q is calculated as follows: The correlation coefficient between the voltage change of grid node q and the start or maintenance of voltage response event j is calculated as follows: The correlation coefficient of the voltage response event j starting or holding and triggering or aborting is calculated as follows: Among them, E p represents the voltage response event set of the power electronic equipment at node p; α ip =0 means that the voltage response event i has no correlation with the power of the grid node p; α ip =1 indicates that the voltage response event i is directly related to the power of the grid node p; ΔU q is the voltage change of the grid node q; ΔP p , ΔQ p They represent the changes in active and reactive power exchange between the power electronic equipment and the grid node p; k P and k Q They represent the weights of active voltage sensitivity and reactive voltage sensitivity respectively; c represents the correlation coefficient bias coefficient; τ j It represents the remaining action time of voltage response event j, which is the difference between the event action time and the current time.

5. The method for searching voltage-dominant cascading failure paths in a power electronic power system according to claim 1, It is characterized in that In step S3, a voltage response event-grid multi-layer coupling network is established in the following manner: CN=(N∪E,C X ,W X ); Where N = {n 1 ,n 2 ,…,n k } represents the set of grid nodes to which the power electronic equipment is connected, k is the number of grid nodes to which the power electronic equipment is connected; E = {e 1 ,e 2 ,…,e m-1 ,e m } represents the voltage response event set, m is the number of voltage response events; W X Represents the weight value matrix of the multi-layer coupling network association relationship; The voltage response event-grid multilayer coupling network includes four single-layer association networks: a grid node association network, a voltage response event association network, a voltage response event and grid node directed association network, and a grid node and voltage response event directed association network. X is a set of multi-layer association relationships between voltage response events and power grids, and C X =C NN ∪C EE ∪C NE ∪C EN , where C NN The grid node association network L NN The set of association relationships, C EE is the voltage response event association network L EE The set of association relationships, C EN is a directed association network L between voltage response events and power grid nodes EN The set of association relationships, C NE is a directed association network L between power grid nodes and voltage response events NE The set of association relationships is determined as follows: Grid node association network L NN The set of association relations C NN is the set of all N(p)→N(q) association relationships, where N(p)→N(q) represents the association relationship between grid node p and grid node q, and N(p) and N(q) represent grid node p and grid node q respectively; Voltage response event association network L EE The set of association relations C EE is the set of all E(i)→E(j) association relationships, where E(i)→E(j) represents the association relationship between voltage response event i and voltage response event j, and E(i) and E(j) represent voltage response event i and voltage response event j respectively; The voltage response event and the directed association network L of the power grid nodes EN The association relationship set C EN is the set of all E(i)→N(p) association relationships, where E(i)→N(p) represents the directed association relationship between voltage response event i and grid node p; Directed association network L between power grid nodes and voltage response events NE The set of association relations C NE It is a set of all N(q)→E(j) association relationships, where N(q)→E(j) represents a directed association relationship between a grid node q and a voltage response event j.

6. The method for searching voltage-dominant cascading failure paths in a power electronic power system according to claim 5, It is characterized in that The grid node association network L NN , voltage response event association network L EE , voltage response events and grid nodes directed association network L EN , the directed association network L between power grid nodes and voltage response events NE Respectively expressed as: L NN =(N,C NN ,W NN ); L EE =(E,C EE ,W EE ); L EN =(E∪N,C EN ,W EN ); L NE =(N∪E,C NE ,W NE ); Where W NN is the weight value matrix of the association relationship between power grid nodes; W EE is the weight value matrix of the unknown correlation relationship of the voltage response event; W EN is the weight value matrix of the directed association relationship between voltage response events and power grid nodes; W NE is the weight value matrix of the directed association relationship between the power grid nodes and the voltage response events; The multi-layer coupling network association relationship weight value matrix W X By W NN , W EN , W NE , W EE The composition is expressed as:

7. The method for searching voltage-dominant cascading failure paths in a power electronic power system according to claim 6, It is characterized in that The weight value matrix W of the association relationship between the grid nodes NN , the weight matrix W of the directed association between voltage response events and grid nodes EN , the weight matrix W of the directed association relationship between grid nodes and voltage response events NE , the weight value matrix W of the unknown correlation relationship of the voltage response event EE The weight values ​​in are determined as follows: Where W NN p,q)∈W NN The weight value representing the association between grid node p and grid node q, β pq is the correlation coefficient between the power exchange of grid node p and the voltage change of grid node q; W EN (i,p)∈W EN The weight value of the directed association relationship between voltage response event i and grid node p, Δ ip is the correlation coefficient for triggering or terminating power exchange with grid node p in response to voltage event i; W NE (q,j)∈W NE The weight value of the directed association relationship between the grid node q and the voltage response event j, θ qj is the correlation coefficient between the voltage change of grid node q and the start or maintenance of voltage response event j; γ j W is the correlation coefficient between starting or maintaining and triggering or stopping of voltage response event j; EE (e i )∈W EE W represents the weight value vector of the unknown correlation between voltage response event i and other voltage response events in the power system; EE (e i ) p (e i ,e j ) represents the weight value of the association relationship between voltage response event j and voltage response event i after any voltage response event i occurs. It is an unknown quantity and needs to be determined by solving.

8. The method for searching voltage-dominant cascading failure paths in a power electronic power system according to claim 1, It is characterized in that In step S4, a random walk model based on voltage response event-grid multi-layer coupling network element path is established in the following manner: Where, CN is the voltage response event-grid multilayer coupling network; MP is the random walk element path; v init is the initial node of the walk; W path (v init ) represents the initial node v init Starting from, the weight value matrix of different walking paths in the meta-path MP; e and n represent the voltage response event node and the power grid node in the voltage response event-power grid multi-layer coupling network respectively.

9. The method for searching voltage-dominant cascading failure paths in a power electronic power system according to claim 1, It is characterized in that In step S5, the random walk model based on the voltage response event-grid multi-layer coupling network element path is solved by: The voltage response event with the action state as the start is the initial node of the particle random walk. According to the random walk model of the voltage response event-grid multi-layer coupling network meta-path, the Markov chain Monte Carlo method is used to randomly select the lower-level nodes of each walk according to the meta-path e→n→n→e, and the corresponding walk path weight is calculated, thereby traversing to obtain the current initial node v init With other different voltage response events as the end point of the wandering path v end The walking path weight is used as the current initial node v init The weight value of the association relationship between the voltage response event node and other voltage response events is calculated, and the order of occurrence of each voltage response event in the power system is determined according to the order of the weight values ​​of the association relationship from large to small.

10. The method for searching voltage-dominant cascading failure paths in a power electronic power system according to claim 9, It is characterized in that The step S5 is specifically as follows: S501: according to the action state of each voltage response event in the current power system determined in step S1, the action state Sta i is started, and the action time is T Thi The shortest voltage response event is the initial node v of the random walk of the particle in the current walk path. init ; S502, according to the action status of each voltage response event in the current power system, determine the correlation process of each current voltage response event in the power system and its corresponding correlation coefficient, and obtain the current correlation relationship weight value matrix of the voltage response event-grid multi-layer coupling network; S503, using the current initial node v init As the starting point, according to the random walk model of the voltage response event-grid multi-layer coupling network meta-path, according to the meta-path MP=e→n→n→e, the Markov chain Monte Carlo method is used to randomly select the lower-level nodes of each walk and calculate the corresponding walk path weight: w p (v init ,v end )=w(v init |v n1 )·w(v n1 |v n2 )·w(v n2 |v end ); In the formula, w p (v init ,v end ) is from the initial node v init Start from the path MP and travel to the end point v of the travel path end The wandering path weight of the voltage response event node is the unknown quantity to be solved, which represents the voltage response from the initial node v init Start, walk along the meta-path e→n→n→e and stop at v end Stop, its wandering path is v init →v n1 →v n2 →v end The walking path weight of v n1 、v n2 represents the two grid nodes passed in the wandering path; w(v init |v n1 ) represents the initial node v init Walk to the first grid node v in the meta-path n1 The walking path weight, w(v n1 |v n2 ) represents the first grid node v in the meta-path n1 Walk to the second grid node v n2 The walking path weight, w(v n2 |v end ) represents the second grid node v in the meta-path n2 Walk to the end of the walk path v end The wandering path weights are all known quantities that can be calculated and determined through the weight value matrix of the correlation relationship between the voltage response event and the multi-layer coupling network of the power grid; This traverses to obtain the current initial node v init With other different voltage response events as the end point of the wandering path v end The walking path weight is used as the current initial node v init The weight value of the association relationship between the voltage response event node and other voltage response events; S504: Determine the current initial node v init Whether the weight values ​​of the association relationships between the voltage response event node and other voltage response events are all 0; If so, the wandering search is terminated; otherwise, the wandering path end point v with the largest weight value of the association relationship is end The corresponding voltage response event is determined as a voltage response event that occurs subsequently; S505, taking the subsequent voltage response event as a new initial node, re-collecting the current working parameters of the power electronic equipment in the power electronic power system, re-determining the action status of each voltage response event in the current power system, and jumping back to step S502; S506, looping through steps S502 to S505 until the wandering search is finished, and determining the order in which each voltage response event in the power system occurs.

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