Voltage stability determination method and system based on short circuit ratios of multiple substations

Abstract

The application discloses a voltage stability determination method based on multi-station short-circuit ratio, comprising the following steps: obtaining data information of a target power system; constructing a global equivalent node impedance matrix of the target power system based on a node admittance equation and a reduced order method; constructing a space load active power shunt contribution coefficient matrix; combining nominal active power output of each new energy station to calculate net external active stress of each new energy station applied to the equivalent alternating current network; calculating a multi-station short-circuit ratio index of the target power system; and completing voltage stability determination of the target power system. The application further discloses a system for implementing the voltage stability determination method based on the multi-station short-circuit ratio. The application not only realizes voltage stability determination of the power system, but also has higher reliability and better accuracy.

Description

Technical Field

[0001] This invention belongs to the field of electrical automation, specifically relating to a voltage stability determination method and system based on the short-circuit ratio of multiple substations. Background Technology

[0002] With economic and technological development and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and daily life, bringing endless convenience. Therefore, ensuring a stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] Currently, power systems widely employ classic metrics such as the Multi-Site Short-Circuit Ratio (MRSCR) and the Generalized Short-Circuit Ratio (GSCR) to evaluate the voltage stability of multi-site grid-connected systems. Traditional evaluation methods typically assume that all power generated by renewable energy stations must be fully carried by the external AC grid. However, in actual large power grids, load centers at various levels are widely distributed within the network topology, and local loads have a significant local absorption and diversion effect on active power flow. Therefore, for stations in heavily loaded areas or near load centers, continuing to use existing evaluation schemes often leads to underestimating the calculated short-circuit ratio, thus greatly affecting the safe and stable operation of the power system. Summary of the Invention

[0004] One of the objectives of this invention is to provide a highly reliable and accurate method for determining voltage stability based on the short-circuit ratio of multiple substations.

[0005] The second objective of this invention is to provide a system for implementing the voltage stability determination method based on the short-circuit ratio of multiple substations.

[0006] The voltage stability determination method based on the short-circuit ratio of multiple power stations provided by this invention includes the following steps:

[0007] S1. Obtain data information about the target power system;

[0008] S2. Based on the data obtained in step S1, construct the global equivalent node impedance matrix of the target power system using the nodal admittance equation and the order reduction method.

[0009] S3. Construct the spatial load active power diversion contribution coefficient matrix;

[0010] S4. Based on the data obtained in step S3, and combined with the nominal active power output of each new energy power station, calculate the net active power stress of each new energy power station applied to the equivalent AC network.

[0011] S5. Based on the data obtained in steps S2 to S4, calculate the multi-station short-circuit ratio index of the target power system;

[0012] S6. Based on the multi-station short-circuit ratio index obtained in step S5, determine the voltage stability of the target power system.

[0013] Step S1, which involves acquiring data information about the target power system, specifically includes the following steps:

[0014] Acquire data information from the target power system;

[0015] The data information includes the topology results of the target power system, the resistance data of the target power system, and the steady-state power flow data of the target power system.

[0016] Step S2, which involves constructing the global equivalent node impedance matrix of the target power system based on the data obtained in step S1, using the nodal admittance equation and the order reduction method, specifically includes the following steps:

[0017] It is set in the target power system, including several new energy power plant nodes, local load nodes, intermediate substation nodes and a main grid infinite node;

[0018] New energy power station nodes constitute an active node set Local load nodes, intermediate substation nodes, and main grid infinite bus nodes constitute a passive node set. ;

[0019] For the target power system, construct the steady-state nodal admittance equations for the entire network:

[0020] In the formula Inject current vectors into the nodes of the new energy power station node set R; Inject current vectors into the nodes of the passive node set N; The admittance submatrix between nodes within the node set R of new energy power stations; Let R be the mutual admittance submatrix between the set of new energy power station nodes R and the set of passive nodes N; Let N be the mutual admittance submatrix between the passive node set N and the new energy power station node set R; Let N be the admittance submatrix between nodes within the set of passive nodes. Let R be the node voltage vector of the set of nodes of the new energy power station; Let N be the node voltage vector of the set of passive nodes.

[0021] set up The equivalent admittance matrix of the generator terminals of the target power system was calculated using a reduction-order method. for ;

[0022] Equivalent admittance matrix at the machine end By performing the inversion operation, the global equivalent nodal impedance matrix of the target power system is obtained. .

[0023] Step S3, which involves constructing the active power shunting contribution coefficient matrix for spatial loads, specifically includes the following steps:

[0024] Based on the data obtained in step S1, the active power matrix of the m local load nodes in the target power system is set. Represented as ,in Let be the active power of the m-th local load node;

[0025] The following formula is used to calculate the weight ratio of the active power generated by the i-th renewable energy power station being locally absorbed by the j-th load node. :

[0026] In the formula Let i be the equivalent transfer admittance from the i-th renewable energy power station to the j-th load node; This represents the total number of new energy power station nodes; Let be the equivalent transfer admittance from the j-th load node to the infinite node of the main network;

[0027] All weighting ratios This constitutes the spatial load active power diversion contribution coefficient matrix of the target power system.

[0028] Step S4, which involves calculating the net active power output stress exerted by each new energy power station on the equivalent AC network based on the data obtained in step S3 and the nominal active power output of each new energy power station, specifically includes the following steps:

[0029] The net active power output stress exerted on the equivalent AC network by the i-th renewable energy power station is calculated using the following formula. :

[0030] In the formula This operation retrieves the maximum value between 0 and 'a'. Let i be the nominal active power output of the i-th renewable energy power station; Let be the active power of the j-th local load node;

[0031] All net external active stress This constitutes the net external active power stress matrix. .

[0032] Step S5, which involves calculating the multi-station short-circuit ratio of the target power system based on the data obtained in steps S2 to S4, specifically includes the following steps:

[0033] System-level generalized short-circuit ratio :

[0034] The global generalized state interaction matrix of the target power system is calculated. for ;in, Let represent a diagonal matrix with the net active power output from each renewable energy power station as its diagonal elements, where the i-th diagonal element is . The off-diagonal elements in the matrix are 0;

[0035] The global generalized state interaction matrix is ​​calculated. The absolute value of the largest eigenvalue ;

[0036] The system-level generalized short-circuit ratio was calculated. for ;

[0037] Station-level multi-station short-circuit ratio :

[0038] The site-level multi-site short-circuit ratio of the i-th renewable energy power station is calculated using the following formula. :

[0039] In the formula The global equivalent nodal impedance matrix The element in the i-th row and i-th column; k is the label of the new energy power station.

[0040] Step S6, which involves determining the voltage stability of the target power system based on the multi-station short-circuit ratio index obtained in step S5, specifically includes the following steps:

[0041] For system-level generalized short-circuit ratio If the system-level generalized short-circuit ratio If the voltage is below a set threshold, the target power system is deemed to have a risk of voltage instability.

[0042] For the short-circuit ratio of multiple stations at the station level The short-circuit ratio index of multiple power stations at the power station level corresponding to new energy power stations. The lower the value, the weaker the voltage support capability at the grid connection point of the renewable energy power station; the more significantly it is affected by power disturbances from other power stations and changes in the external grid structure; and the higher the risk of difficulty in voltage recovery after voltage instability or faults. The multi-station short-circuit ratio index corresponding to the renewable energy power station... The higher the value, the stronger the voltage support capability of the grid connection point where the new energy power station is located, the smaller the net active power stress transmitted, and the higher the system's acceptance margin and voltage recovery capability after a fault.

[0043] This invention also provides a system for implementing the voltage stability determination method based on the short-circuit ratio of multiple power stations, including a data acquisition module, an impedance construction module, a contribution calculation module, an external transmission calculation module, an index calculation module, and a voltage determination module; the data acquisition module, impedance construction module, contribution calculation module, external transmission calculation module, index calculation module, and voltage determination module are connected in series; the data acquisition module is used to acquire data information of the target power system and upload the data information to the impedance construction module; the impedance construction module is used to construct the global equivalent node impedance matrix of the target power system based on the received data information and the acquired data information, based on the node admittance equation and the order reduction method, and upload the data information to the contribution calculation module; the contribution calculation module is used for... Based on the received data, a spatial load active power shunting contribution coefficient matrix is ​​constructed, and the data is uploaded to the external transmission calculation module. The external transmission calculation module calculates the net external active power stress exerted by each new energy power station on the equivalent AC network based on the received and obtained data, combined with the nominal active power output of each new energy power station, and uploads the data to the index calculation module. The index calculation module calculates the multi-station short-circuit ratio index of the target power system based on the received and obtained data, and uploads the data to the voltage determination module. The voltage determination module determines the voltage stability of the target power system based on the received data and the obtained multi-station short-circuit ratio index.

[0044] The voltage stability determination method and system based on the short-circuit ratio of multiple substations provided by this invention constructs the global equivalent node impedance matrix and the spatial load active power shunting contribution coefficient matrix of the target power system by considering the load shunting effect, and calculates the short-circuit ratio index of multiple substations of the target power system based on the constructed matrix and completes the corresponding determination. This not only realizes the voltage stability determination of the power system, but also has higher reliability and better accuracy. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0046] Figure 2 This is a simplified topology diagram of a multi-wind farm grid-connected system (including local loads) according to an embodiment of the method of the present invention.

[0047] Figure 3 This is a schematic diagram of the transient response waveform of the terminal voltage under the N-1 fault condition when using a traditional evaluation system that does not take into account the load shunting effect, as an embodiment of the method of the present invention.

[0048] Figure 4 This is a schematic diagram of the transient response waveform of the terminal voltage under the N-1 fault condition when the solution of the present invention is adopted in the embodiment of the present invention.

[0049] Figure 5 This is a schematic diagram of the functional modules of the system of the present invention. Detailed Implementation

[0050] like Figure 1 The diagram shown is a flowchart of the method of the present invention: The voltage stability determination method based on the short-circuit ratio of multiple substations provided by the present invention includes the following steps:

[0051] S1. Obtain data information of the target power system; specifically including the following steps:

[0052] Acquire data information from the target power system;

[0053] The data information includes the topology results of the target power system, the resistance data of the target power system, and the steady-state power flow data of the target power system;

[0054] S2. Based on the data obtained in step S1, construct the global equivalent node impedance matrix of the target power system using the nodal admittance equation and the order reduction method; specifically, this includes the following steps:

[0055] It is set in the target power system, including several new energy power plant nodes, local load nodes, intermediate substation nodes and a main grid infinite node;

[0056] New energy power station nodes constitute an active node set Local load nodes, intermediate substation nodes, and main grid infinite bus nodes constitute a passive node set. ;

[0057] For the target power system, construct the steady-state nodal admittance equations for the entire network:

[0058] In the formula Inject current vectors into the nodes of the new energy power station node set R; Inject current vectors into the nodes of the passive node set N; The admittance submatrix between nodes within the node set R of new energy power stations; Let R be the mutual admittance submatrix between the set of new energy power station nodes R and the set of passive nodes N; Let N be the mutual admittance submatrix between the passive node set N and the new energy power station node set R; Let N be the admittance submatrix between nodes within the set of passive nodes. Let R be the node voltage vector of the set of nodes of the new energy power station; Let N be the node voltage vector of the set of passive nodes.

[0059] To extract the inherent physical coupling strength between new energy power stations, passive and load nodes are assumed to have no independent power injection, i.e., a threshold is set. And by using a reduction-order method (such as Kron's reduction-order method), the equivalent admittance matrix of the generator terminals of the target power system is calculated. for ;

[0060] Equivalent admittance matrix at the machine end By performing the inversion operation, the global equivalent nodal impedance matrix of the target power system is obtained. ;matrix In the middle, diagonal elements Characterizing the system's ability to support the absolute short-circuit capacity of the i-th renewable energy power station, off-diagonal elements Characterizes the electrical coupling strength between stations;

[0061] S3. Construct the active power shunting contribution coefficient matrix for spatial loads; specifically including the following steps:

[0062] Based on the data obtained in step S1, the active power matrix of the m local load nodes in the target power system is set. Represented as ,in Let be the active power of the m-th local load node;

[0063] Based on the principle of proximity consumption over electrical distance in the AC power grid, the following formula is used to calculate the weighting ratio of the active power generated by the i-th renewable energy power station being locally consumed by the j-th load node. :

[0064] In the formula Let i be the equivalent transfer admittance from the i-th renewable energy power station to the j-th load node; This represents the total number of new energy power station nodes; Let be the equivalent transfer admittance from the j-th load node to the infinite node of the main network;

[0065] All weighting ratios This constitutes the spatial load active power diversion contribution coefficient matrix of the target power system;

[0066] S4. Based on the data obtained in step S3, and combined with the nominal active power output of each renewable energy power station, calculate the net active power stress exerted by each renewable energy power station on the equivalent AC network; specifically including the following steps:

[0067] After deducting the active power share equivalent to that absorbed by local load, the net active power stress exerted by the i-th renewable energy power station on the equivalent AC network is calculated using the following formula. :

[0068] In the formula This operation retrieves the maximum value between 0 and 'a'. Let i be the nominal active power output of the i-th renewable energy power station; Let j be the active power of the j-th local load node; function The physical essence of the nonlinear physical cutoff boundary is that when the load absorption equivalently allocated to a certain power station is greater than the power output of the power station itself, the active stress injected by the power station into the external power grid is cut off to zero.

[0069] All net external active stress This constitutes the net external active power stress matrix. ;

[0070] S5. Based on the data obtained in steps S2 to S4, calculate the multi-station short-circuit ratio of the target power system; specifically, this includes the following steps:

[0071] System-level generalized short-circuit ratio :

[0072] The global generalized state interaction matrix of the target power system is calculated. for ;in, Let represent a diagonal matrix with the net active power output from each renewable energy power station as its diagonal elements, where the i-th diagonal element is . The off-diagonal elements in the matrix are 0;

[0073] The global generalized state interaction matrix is ​​calculated. The absolute value of the largest eigenvalue ;

[0074] The system-level generalized short-circuit ratio was calculated. for ;

[0075] Station-level multi-station short-circuit ratio :

[0076] The site-level multi-site short-circuit ratio of the i-th renewable energy power station is calculated using the following formula. :

[0077] In the formula The global equivalent nodal impedance matrix The element in the i-th row and i-th column; k is the label of the new energy power station;

[0078] S6. Based on the multi-station short-circuit ratio index obtained in step S5, determine the voltage stability of the target power system; specifically, this includes the following steps:

[0079] For system-level generalized short-circuit ratio If the system-level generalized short-circuit ratio If the voltage is below a set threshold, the target power system is deemed to have a risk of voltage instability.

[0080] For the short-circuit ratio of multiple stations at the station level The short-circuit ratio index of multiple power stations at the power station level corresponding to new energy power stations. The lower the value, the weaker the voltage support capability at the grid connection point of the renewable energy power station; the more significantly it is affected by power disturbances from other power stations and changes in the external grid structure; and the higher the risk of difficulty in voltage recovery after voltage instability or faults. The multi-station short-circuit ratio index corresponding to the renewable energy power station... The higher the value, the stronger the voltage support capability of the grid connection point where the new energy power station is located, the smaller the net active power stress transmitted, and the higher the system's acceptance margin and voltage recovery capability after a fault.

[0081] The method of the present invention will be further described below with reference to an embodiment:

[0082] by Figure 2 The power system shown is the opposite side. The specific verification is explained by combining the topology of dual substations connected to a single grid connection point and the parameter data of the actual simulation software (PSD-BPA).

[0083] Figure 2 In this model, the target AC power grid includes the main grid equivalent node (i.e., node B01 in the BPA model), the point of common coupling (PCC, i.e., node B02), and two renewable energy power plants (wind farm 1 and wind farm 2). The system baseline capacity is set at 100 MVA.

[0084] Line parameters: The PCC is connected to the main grid via a double-circuit AC line, with single-circuit line reactance... Under the N-1 fault condition (disconnection of one circuit), the equivalent reactance of the main grid is... .

[0085] Site parameters: The nominal active power output of wind farm 1 and wind farm 2 are both... ,Right now Each substation is connected via a transformer (reactor). ) and step-up transformer (reactor) The circuit is connected to the PCC; therefore, the equivalent branch reactance of each station is... .

[0086] Impedance Extraction: After network order reduction, the self-impedance of the two stations looking towards the main network under the N-1 fault condition is obtained. Mutual impedance between the two stations .

[0087] Comparison Condition 1: No load (traditional multi-station short-circuit ratio)

[0088] When there is no local load at PCC (load) The total number of [items] issued by the two stations All active power will be transmitted. According to the traditional multi-station short-circuit ratio (MRSCR) formula, when the system is in the N-1 operating condition, the classic short-circuit ratio of wind farm 1 is: ;

[0089] The index of 0.98 is far below the system stability critical value (usually 1.5), and the assessment conclusion is an extremely weak network. When an N-1 fault test is performed in the PSD-BPA transient simulation software, the system voltage cannot recover, resulting in instability and collapse, as shown in the graph below. Figure 3 As shown;

[0090] Comparison Condition 2: With local heavy load (short-circuit ratio of multiple substations):

[0091] When PCC has Local load (load) The reconstruction evaluation is performed using the method of this invention;

[0092] Based on the electrical distance, the local load proportionally absorbed the power generated by the two power stations. The power absorbed by each power station was... Then, after reconstruction, the net active power stress injected into the equivalent AC network by the two stations is sharply reduced to ;

[0093] According to the multi-station short-circuit ratio formula considering load diversion at the station level of this invention, the actual intensity index of wind farm 1 under the N-1 condition is calculated as follows: ;

[0094] After correction using the method of this invention, the actual index rose to 1.96, far higher than the 0.98 calculated by the traditional method. When the same N-1 fault test was performed in the PSD-BPA transient simulation software, the terminal voltage recovered smoothly after the fault was cleared, and the system continued to operate stably. The curve is shown below. Figure 4 As shown.

[0095] As can be seen from the embodiments, the present invention can explicitly take into account the active power diversion and local absorption of local loads in a multi-new energy power station access system, avoiding the overly conservative assessment caused by equating the total output of new energy power stations entirely with the external power transmission stress. Compared with the traditional multi-station short-circuit ratio, the present invention can more accurately reflect the net external active power stress exerted by new energy power stations on the external AC network, making the calculation results more consistent with the fault transient voltage recovery characteristics, thereby improving the accuracy of weak grid connection point identification, voltage stability determination, and new energy access margin assessment.

[0096] like Figure 5 The diagram shows the functional modules of the system of the present invention: The system disclosed in this invention for implementing the voltage stability determination method based on the short-circuit ratio of multiple power stations includes a data acquisition module, an impedance construction module, a contribution calculation module, an external transmission calculation module, an index calculation module, and a voltage determination module; the data acquisition module, impedance construction module, contribution calculation module, external transmission calculation module, index calculation module, and voltage determination module are connected in series; the data acquisition module is used to acquire data information of the target power system and upload the data information to the impedance construction module; the impedance construction module is used to construct the global equivalent node impedance matrix of the target power system based on the received data information and the acquired data information, based on the node admittance equation and the order reduction method, and upload the data information to the contribution calculation module; The contribution calculation module constructs a spatial load active power shunting contribution coefficient matrix based on the received data and uploads the data to the external transmission calculation module. The external transmission calculation module calculates the net external active power stress exerted by each new energy power station on the equivalent AC network based on the received and obtained data, combined with the nominal active power output of each new energy power station, and uploads the data to the index calculation module. The index calculation module calculates the multi-station short-circuit ratio index of the target power system based on the received and obtained data and uploads the data to the voltage determination module. The voltage determination module determines the voltage stability of the target power system based on the received data and the obtained multi-station short-circuit ratio index.

Claims

1. A voltage stability determination method based on the short-circuit ratio of multiple substations, comprising the following steps: S1. Obtain data information about the target power system; S2. Based on the data obtained in step S1, construct the global equivalent node impedance matrix of the target power system using the nodal admittance equation and the order reduction method. S3. Construct the spatial load active power diversion contribution coefficient matrix; S4. Based on the data obtained in step S3, and combined with the nominal active power output of each new energy power station, calculate the net active power stress of each new energy power station applied to the equivalent AC network. S5. Based on the data obtained in steps S2 to S4, calculate the multi-station short-circuit ratio index of the target power system; S6. Based on the multi-station short-circuit ratio index obtained in step S5, determine the voltage stability of the target power system.

2. The method for voltage stability determination based on multi-zone short circuit ratio according to claim 1, characterized in that Step S1, which involves acquiring data information about the target power system, specifically includes the following steps: Acquire data information from the target power system; The data information includes the topology results of the target power system, the resistance data of the target power system, and the steady-state power flow data of the target power system.

3. The voltage stability determination method based on the short-circuit ratio of multiple substations according to claim 2, characterized in that... Step S2, which involves constructing the global equivalent node impedance matrix of the target power system based on the data obtained in step S1, using the nodal admittance equation and the order reduction method, specifically includes the following steps: It is set in the target power system, including several new energy power plant nodes, local load nodes, intermediate substation nodes and a main grid infinite node; New energy power station nodes constitute an active node set Local load nodes, intermediate substation nodes, and main grid infinite bus nodes constitute a passive node set. ; For the target power system, construct the steady-state nodal admittance equations for the entire network: In the formula Inject current vectors into the nodes of the new energy power station node set R; Inject current vectors into the nodes of the passive node set N; The admittance submatrix between nodes within the node set R of new energy power stations; Let R be the mutual admittance submatrix between the set of new energy power station nodes R and the set of passive nodes N; Let N be the mutual admittance submatrix between the passive node set N and the new energy power station node set R; Let N be the admittance submatrix between nodes within the set of passive nodes. Let R be the node voltage vector of the set of nodes of the new energy power station; Let N be the node voltage vector of the passive node set N; set up The equivalent admittance matrix of the generator terminals of the target power system was calculated using a reduction-order method. for ; Equivalent admittance matrix at the machine end By performing the inversion operation, the global equivalent nodal impedance matrix of the target power system is obtained. .

4. The voltage stability determination method based on the short-circuit ratio of multiple substations according to claim 3, characterized in that... Step S3, which involves constructing the active power shunting contribution coefficient matrix for spatial loads, specifically includes the following steps: Based on the data obtained in step S1, the active power matrix of the m local load nodes in the target power system is set. Represented as ,in Let be the active power of the m-th local load node; The following formula is used to calculate the weight ratio of the active power generated by the i-th renewable energy power station being locally absorbed by the j-th load node. : In the formula Let i be the equivalent transfer admittance from the i-th renewable energy power station to the j-th load node; This represents the total number of new energy power station nodes; Let be the equivalent transfer admittance from the j-th load node to the infinite node of the main network; All weighting ratios This constitutes the spatial load active power diversion contribution coefficient matrix of the target power system.

5. The voltage stability determination method based on the short-circuit ratio of multiple substations according to claim 4, characterized in that... Step S4, which involves calculating the net active power output stress exerted by each new energy power station on the equivalent AC network based on the data obtained in step S3 and the nominal active power output of each new energy power station, specifically includes the following steps: The net active power output stress exerted on the equivalent AC network by the i-th renewable energy power station is calculated using the following formula. : In the formula This operation retrieves the maximum value between 0 and 'a'. Let i be the nominal active power output of the i-th renewable energy power station; Let be the active power of the j-th local load node; All net external active power stress This constitutes the net external active power stress matrix. .

6. The voltage stability determination method based on the short-circuit ratio of multiple substations according to claim 5, characterized in that... Step S5, which involves calculating the multi-station short-circuit ratio of the target power system based on the data obtained in steps S2 to S4, specifically includes the following steps: System-level generalized short-circuit ratio : The global generalized state interaction matrix of the target power system is calculated. for ;in, Let represent a diagonal matrix with the net active power output from each renewable energy power station as its diagonal elements, where the i-th diagonal element is . The off-diagonal elements in the matrix are 0; The global generalized state interaction matrix is ​​calculated. The absolute value of the largest eigenvalue ; The system-level generalized short-circuit ratio was calculated. for ; Station-level multi-station short-circuit ratio : The site-level multi-site short-circuit ratio of the i-th renewable energy power station is calculated using the following formula. : In the formula The global equivalent nodal impedance matrix The element in the i-th row and i-th column; k is the label of the new energy power station.

7. The voltage stability determination method based on the short-circuit ratio of multiple substations according to claim 6, characterized in that... Step S6, which involves determining the voltage stability of the target power system based on the multi-station short-circuit ratio index obtained in step S5, specifically includes the following steps: For system-level generalized short-circuit ratio If the system-level generalized short-circuit ratio If the voltage is below a set threshold, the target power system is deemed to have a risk of voltage instability. For the short-circuit ratio of multiple stations at the station level The short-circuit ratio index of multiple power stations at the power station level corresponding to new energy power stations. The lower the value, the weaker the voltage support capability at the grid connection point of the new energy power station; the more power station-level multi-station short-circuit ratio index corresponds to the new energy power station. The higher the value, the stronger the voltage support capability of the grid connection point where the new energy power station is located.

8. A system for implementing the voltage stability determination method based on the short-circuit ratio of multiple substations as described in any one of claims 1 to 7, characterized in that... It includes a data acquisition module, an impedance construction module, a contribution calculation module, an external transmission calculation module, an index calculation module, and a voltage determination module; these modules are connected in series. The data acquisition module acquires data information of the target power system and uploads it to the impedance construction module. The impedance construction module constructs the global equivalent node impedance matrix of the target power system based on the received and acquired data information, using the nodal admittance equation and the order reduction method, and uploads the data information to the contribution calculation module. The contribution calculation module is used to construct the spatial load active power diversion contribution coefficient matrix based on the received data information, and upload the data information to the external calculation module; The external transmission calculation module is used to calculate the net external active power stress exerted by each new energy power station on the equivalent AC network based on the received data information and the nominal active power output of each new energy power station, and upload the data information to the index calculation module. The index calculation module is used to calculate the multi-station short-circuit ratio index of the target power system based on the received data information and upload the data information to the voltage determination module. The voltage determination module is used to determine the voltage stability of the target power system based on the received data and the obtained short-circuit ratio index of multiple substations.

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