Networking type SVG locating and sizing method and device, storage medium and electronic equipment

Abstract

The invention discloses a network construction type SVG locating and sizing method and device, a storage medium and electronic equipment, and relates to the technical field of power grid control. The invention aims to solve the problem that the existing addressing and sizing cannot reflect the voltage support strength of the system and the frequency stability of each node at the same time. According to the method, an augmented admittance matrix is obtained by using system parameters; respectively calculating the inertia of a generator node and other network nodes in the system; when the minimum inertia value of other network nodes in the system is smaller than the critical inertia, the sensitivity of the minimum inertia value of other network nodes to the inertia of each generator node is calculated, and a network-forming SVG is configured at the generator node with the highest sensitivity; otherwise, respectively calculating the access point short-circuit ratio and the grid-connected point short-circuit ratio of the new energy station; and when the short-circuit ratios of the new energy station access point and the grid-connected point are both smaller than the access point critical short-circuit ratio, configuring a network construction type SVG at the grid-connected bus node with the minimum short-circuit ratio, otherwise, indicating that the current system does not need to be configured with the SVG.

Description

Technical Field

[0001] The invention belongs to the technical field of power grid control, and in particular relates to site selection and capacity determination of a grid-forming SVG. Background Art

[0002] After large-scale new energy is connected to the grid, the weak support of new energy power generation equipment makes it difficult for the voltage and frequency support strength of the connected grid to meet the safety and stability requirements of the grid. For wind and solar power stations, the grid-forming SVG (static var generator) can provide the system with rotational inertia while providing voltage support. By configuring the grid-forming SVG, the system inertia level and short-circuit ratio can be effectively improved, thereby improving the grid frequency and voltage support strength. However, in the current power system, the configuration method of the grid-forming SVG has yet to be studied. Therefore, it is of great significance to formulate an efficient and feasible grid-forming SVG site selection and capacity determination strategy.

[0003] In order to ensure that the system frequency can be maintained within the allowable range and avoid frequency collapse, the frequency stability constraint can be used as an indicator for the site selection and capacity determination of the meshed SVG. The node inertia theory is used to evaluate the system inertia distribution and find the weak inertia nodes. The inertia sensitivity is calculated to guide the site selection of the meshed SVG, and then the frequency change rate and the maximum frequency deviation are used as constraints to determine the capacity of the meshed SVG. However, this site selection and capacity determination method uses node inertia as an indicator, which essentially reflects the stability of the frequency of each node in the system after the disturbance occurs, but does not reflect the system voltage support strength, and cannot guarantee the safety and stability of the system voltage after the disturbance occurs.

[0004] In order to ensure that the system voltage can be maintained within the allowable range and avoid transient overvoltage, the voltage stability constraint can be used as an indicator for the site selection and capacity determination of the grid-type SVG. Based on the quantitative evaluation of the short-circuit ratio of new energy sites on the voltage support strength of the power grid, the impact of the access of the grid-type SVG on the short-circuit ratio of new energy sites is analyzed, and the site selection plan of the grid-type SVG is obtained. The capacity of the grid-type SVG is determined based on the critical short-circuit ratio of the system's new energy site and the critical short-circuit ratio of the new energy site connection point. However, this site selection and capacity determination method uses the short-circuit ratio of new energy sites as an indicator, which essentially reflects the voltage support strength of each node in the system, but does not reflect the frequency stability of each node in the system, and cannot guarantee the safety and stability of the system frequency after a disturbance occurs. Summary of the invention

[0005] The present invention aims to solve the problem that the site selection and capacity determination of the existing mesh-type SVG cannot simultaneously reflect the system voltage support strength and the frequency stability of each node. To solve this problem, the present invention proposes a mesh-type SVG site selection and capacity determination method, which takes inertia and short-circuit ratio as indicators, and simultaneously considers the system voltage support strength and frequency support strength, thereby ensuring the stable operation of the system after a disturbance occurs.

[0006] The site selection and capacity determination method of the network-based SVG includes:

[0007] The augmented admittance matrix of the power system is obtained by using the line parameters and unit parameters of the power system.

[0008] Based on the augmented admittance matrix, respectively calculate the inertia of the generator node and other network nodes in the power system;

[0009] Determine whether the minimum inertia of other network nodes in the power system is greater than the critical inertia of the power system. If so, calculate the short-circuit ratio of the access point of the new energy station and the short-circuit ratio of the grid connection point respectively. Otherwise, calculate the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node, and configure the network-type SVG at the generator node with the highest sensitivity.

[0010] Determine whether the short-circuit ratios of the new energy station access point and the grid-connected point are both greater than their respective critical short-circuit ratios. If so, it means that the current power system does not need to configure SVG. Otherwise, configure a grid-connected SVG at the grid-connected bus node with the smallest short-circuit ratio.

[0011] Furthermore, the augmented admittance matrix of the power system is obtained by using the line parameters and unit parameters of the power system, including:

[0012] Assume that the power system has a total of N+M nodes, including N generator nodes and M other network nodes, then the augmented admittance matrix Y of the power system is s The expression is:

[0013]

[0014] Among them, Y N is the diagonal array formed after the transient reactance of the generator is converted into admittance, Y NN and Y MM are the self-admittances of the generator node and other network nodes, Y lN and Y lM are the equivalent admittances of the loads at the generator nodes and other network nodes after being simplified to equivalent admittances, Y NM and Y MN are the mutual admittances of the generator node and other network nodes respectively.

[0015] Furthermore, the above-mentioned calculation of the inertia of the generator node and other network nodes in the power system based on the augmented admittance matrix includes:

[0016] The inertia of the generator node in the power system is calculated by the following formula:

[0017]

[0018] Among them, H nis the inertia of the nth generator node, n=1,2,...,N, G and Q represent the number of synchronous generators and renewable energy units under the nth generator node, respectively, S g and S q They represent the capacity of the g-th synchronous generator and the q-th new energy unit, respectively. g is the inertia time constant of the g-th synchronous generator;

[0019] The inertia of other network nodes in the power system is calculated by the following formula:

[0020]

[0021] Among them, H m is the inertia of the mth other network node, m=1,2,...,M, B nm is the susceptance between the nth generator node and the mth other network node in the augmented admittance matrix, r mn is the element in the matrix R corresponding to the voltage relationship between the mth other network node and the nth generator node. The matrix R is U e and U net The correlation matrix between

[0022] U e and U net are the voltages of the generator node and other network nodes, and U net =RU e .

[0023] Furthermore, the above-mentioned critical inertia of the power system includes: the critical inertia of the power system based on the frequency change rate constraint and the critical inertia of the power system based on the maximum frequency deviation constraint;

[0024] When the minimum node inertia is greater than the critical inertia of the power system based on the frequency change rate constraint and the critical inertia of the power system based on the maximum frequency deviation constraint, the short-circuit ratio of the new energy station access point and the short-circuit ratio of the grid connection point are calculated respectively; otherwise, the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node is calculated, and the meshing type SVG is configured at the generator node with the highest sensitivity.

[0025] Furthermore, the critical inertia of the power system based on the frequency change rate constraint is The expression is:

[0026]

[0027] Among them, ΔP max is the maximum disturbance power, RoCoF max is the maximum frequency change rate of the power system;

[0028] The critical inertia of the power system based on the maximum frequency deviation constraint The expression is:

[0029]

[0030] Among them, f B is the reference frequency, t nadir is the moment when the lowest frequency point occurs, is the maximum frequency deviation of the power system.

[0031] Furthermore, the above calculation of the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node includes:

[0032]

[0033] Among them, H min is the minimum inertia value of other network nodes, and the serial number of other network nodes corresponding to the minimum inertia value of other network nodes is recorded as x, x = 1, 2, ..., M; B nx is the susceptance between the nth generator node and the xth other network node in the augmented admittance matrix, r xn is the element in the matrix R corresponding to the voltage relationship between the xth other network node and the nth generator node.

[0034] Furthermore, the above respectively calculates the short-circuit ratio of the access point of the new energy station and the short-circuit ratio of the grid connection point, including:

[0035]

[0036] Among them, MESCR r is the short-circuit ratio at the rth access point / grid connection point of the new energy station, U Nr is the nominal voltage of the rth access point / grid connection point of the new energy station, U REr I is the voltage generated by the power generated by the new energy equipment / station at the rth access point / grid connection point, r and I e are the short-circuit currents provided to the rth and eth access points / grid-connected points, W is the total number of access points / grid-connected points, and Z eqrr Z eq The r-th row and r-th column element of Z eqre Z eq The rth row and eth column element of Z eq is the AC grid equivalent impedance matrix at the rth access point / grid connection point of the new energy station, and Z eq and the augmented admittance matrix Y s are inverse matrices of each other.

[0037] The network-type SVG site selection and volume determination device includes:

[0038] Augmented admittance matrix calculation unit: using the line parameters and unit parameters of the power system to obtain the augmented admittance matrix of the power system;

[0039] Inertia calculation unit: calculates the inertia of the generator node and other network nodes in the power system respectively based on the augmented admittance matrix;

[0040] Inertia judgment unit: judge whether the minimum inertia of other network nodes in the power system is greater than the critical inertia of the power system;

[0041] Sensitivity calculation unit: when the minimum inertia of other network nodes in the power system is less than the critical inertia of the power system, the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node is calculated, and the meshing type SVG is configured at the generator node with the highest sensitivity;

[0042] Short-circuit ratio calculation unit: when the minimum inertia of other network nodes in the power system is greater than the critical inertia of the power system, the short-circuit ratio of the new energy station access point and the short-circuit ratio of the grid connection point are calculated respectively;

[0043] Short-circuit ratio judgment unit: judge whether the short-circuit ratios of the access point and the grid connection point of the new energy station are both greater than their respective critical short-circuit ratios. When the short-circuit ratios of the access point and the grid connection point of the new energy station are both greater than their respective critical short-circuit ratios, it means that the current power system does not need to configure SVG.

[0044] Otherwise, a grid-forming SVG is configured at the grid-connected bus node with the smallest short-circuit ratio.

[0045] Furthermore, the augmented admittance matrix of the power system is obtained by using the line parameters and unit parameters of the power system, including:

[0046] Assume that the power system has a total of N+M nodes, including N generator nodes and M other network nodes, then the augmented admittance matrix Y of the power system is s The expression is:

[0047]

[0048] Among them, Y N is the diagonal array formed after the transient reactance of the generator is converted into admittance, Y NN and Y MM are the self-admittances of the generator node and other network nodes, Y lN and Y lM are the equivalent admittances of the loads at the generator nodes and other network nodes after being simplified to equivalent admittances, Y NM and Y MN are the mutual admittances of the generator node and other network nodes respectively.

[0049] Furthermore, the above-mentioned calculation of the inertia of the generator node and other network nodes in the power system based on the augmented admittance matrix includes:

[0050] The inertia of the generator node in the power system is calculated by the following formula:

[0051]

[0052] Among them, H n is the inertia of the nth generator node, n=1,2,...,N, G and Q represent the number of synchronous generators and renewable energy units under the nth generator node, respectively, S g and S q They represent the capacity of the g-th synchronous generator and the q-th new energy unit, respectively. g is the inertia time constant of the g-th synchronous generator;

[0053] The inertia of other network nodes in the power system is calculated by the following formula:

[0054]

[0055] Among them, H m is the inertia of the mth other network node, m=1,2,...,M, B nm is the susceptance between the nth generator node and the mth other network node in the augmented admittance matrix, r mn is the element in the matrix R corresponding to the voltage relationship between the mth other network node and the nth generator node. The matrix R is U e and U net The correlation matrix between Y 3 =[-Y N 0] T ,

[0056] U e and U net are the voltages of the generator node and other network nodes, and U net =RU e .

[0057] Furthermore, the above-mentioned critical inertia of the power system includes: the critical inertia of the power system based on the frequency change rate constraint and the critical inertia of the power system based on the maximum frequency deviation constraint;

[0058] When the minimum node inertia is greater than the critical inertia of the power system based on the frequency change rate constraint and the critical inertia of the power system based on the maximum frequency deviation constraint, the short-circuit ratio of the new energy station access point and the short-circuit ratio of the grid connection point are calculated respectively. Otherwise, the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node is calculated, and the meshing type SVG is configured at the generator node with the highest sensitivity.

[0059] Furthermore, the critical inertia of the power system based on the frequency change rate constraint is The expression is:

[0060]

[0061] Among them, ΔP max is the maximum disturbance power, RoCoF max is the maximum frequency change rate of the power system;

[0062] The critical inertia of the power system based on the maximum frequency deviation constraint The expression is:

[0063]

[0064] Among them, f B is the reference frequency, t nadir is the moment when the lowest frequency point occurs, is the maximum frequency deviation of the power system.

[0065] Furthermore, the above calculation of the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node includes:

[0066]

[0067] Among them, H min is the minimum inertia value of other network nodes, and the serial number of other network nodes corresponding to the minimum inertia value of other network nodes is recorded as x, x = 1, 2, ..., M; B nx is the susceptance between the nth generator node and the xth other network node in the augmented admittance matrix, r xn is the element in the matrix R corresponding to the voltage relationship between the xth other network node and the nth generator node.

[0068] Furthermore, the above respectively calculates the short-circuit ratio of the access point of the new energy station and the short-circuit ratio of the grid connection point, including:

[0069]

[0070] Among them, MESCR r is the short-circuit ratio at the rth access point / grid connection point of the new energy station, UNr is the nominal voltage of the rth access point / grid connection point of the new energy station, U REr I is the voltage generated by the power generated by the new energy equipment / station at the rth access point / grid connection point, r and I e are the short-circuit currents provided to the rth and eth access points / grid-connected points, W is the total number of access points / grid-connected points, and Z eqrr Z eq The r-th row and r-th column element of Z eqre Z eq The rth row and eth column element of Z eq is the AC grid equivalent impedance matrix at the rth access point / grid connection point of the new energy station, and Z eq and the augmented admittance matrix Y s are inverse matrices of each other.

[0071] A computer-readable storage medium stores a computer program, and when the computer program is executed, the method for selecting a site and determining the capacity of a mesh-type SVG is implemented.

[0072] An electronic device includes a storage medium, a processor, and a computer program stored in the storage medium and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned method for selecting and determining the location and capacity of a meshed SVG.

[0073] The present invention proposes a method for site selection and sizing of a network-type SVG. The method uses inertia and short-circuit ratio as indicators, considers critical inertia and critical short-circuit ratio limits for sizing, and satisfies system voltage support strength and frequency support strength at the same time, thereby ensuring stable operation of the system after a disturbance occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 This is a flowchart of site selection and capacity determination for the network-based SVG proposed in the present invention;

[0075] Figure 2 This is the WSCC9 node system diagram including wind turbines;

[0076] Figure 3 It is a bar chart of the inertia sensitivity of each node of the WSCC9 system to the SVG installation node. DETAILED DESCRIPTION

[0077] The following will be combined with the accompanying 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, rather than 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 belong to the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0078] Specific implementation method 1: refer to Figure 1 Specifically describing this embodiment, the method for selecting a site and determining a volume of a network-based SVG described in this embodiment includes:

[0079] Step 1: Read the grid structure, line parameters and unit parameters of the power system, and calculate the system critical inertia considering the maximum frequency deviation and frequency change rate according to the power disturbance of the power system.

[0080] The rate of change of frequency of the power system RoCoF is an important indicator to measure the frequency safety and stability of the system after a disturbance occurs, and its size mainly depends on the system inertia level. The maximum frequency change rate after the system is disturbed is proportional to the disturbance power and inversely proportional to the inertia size. The larger the disturbance power and the lower the system inertia, the easier it is to trigger the protection action. The frequency does not change at the moment of the disturbance, and the frequency regulation effect of the generator and load in the system does not work. The frequency change only depends on the size of the system inertia and the disturbance power. Critical inertia of power system based on frequency change rate constraint for:

[0081]

[0082] Among them, ΔP max is the maximum disturbance power, RoCoF max is the maximum frequency change rate of the power system.

[0083] When the maximum disturbance power ΔP occurs in the system max In order to make the center of inertia RoCoF not exceed the threshold RoCoF max , the power system inertia should be greater than

[0084] Without considering the frequency regulation of generators and loads, the maximum frequency deviation mainly depends on the inertia level and primary frequency regulation capability. The greater the inertia level and primary frequency regulation capability of the power system, the smaller the maximum frequency deviation of the system after the disturbance occurs. In order to ensure that the frequency deviation is within the safety constraint range, In order to avoid collapse, the system should have sufficient inertia level to cope with various disturbances; the system frequency deviation depends on the initial power shortage and system inertia, and has a linear relationship with time. According to the frequency response model of the multi-machine system, the critical inertia of the power system under the maximum frequency deviation constraint of the power system is derived. The expression is:

[0085]

[0086] Among them, f B is the reference frequency, t nadir is the moment when the lowest frequency point occurs, is the maximum frequency deviation of the power system.

[0087] It can be seen that in a power system with low inertia, RoCoF max and In summary, the boundary inertia level that satisfies these two indicators within the safe range after the disturbance is the critical inertia considering the frequency stability constraint.

[0088] Step 2: Use the line parameters and unit parameters of the power system to obtain the augmented admittance matrix of the power system.

[0089] Assuming that there are N+M nodes in a power system, including N generator nodes and M other network nodes, the augmented admittance matrix Y of the power system is s The expression is:

[0090]

[0091] Among them, Y N is the diagonal array formed after the transient reactance of the generator is converted into admittance, Y NN and Y MM are the self-admittances of the generator node and other network nodes, Y lN and Y lM are the equivalent admittances of the loads at the generator nodes and other network nodes after being simplified to equivalent admittances, Y NM and Y MN are the mutual admittances of the generator node and other network nodes respectively, and the conductance is neglected.

[0092] The network equation of the power system is:

[0093]

[0094] Among them, I n U is the current input from the potential node in the generator to the network; e and U netare the voltages of the generator node and other network nodes respectively; Y 1 , Y 2 , Y 3 , Y 4 They are the augmented admittance matrices Y s of four regions, including:

[0095] Y 1 =Y N , Y 2 =[-Y N 0]、Y 3 =[-Y N 0] T ,

[0096] Step 3: Calculate the inertia of the generator node in the power system by the following formula:

[0097]

[0098] Among them, H n is the inertia of the nth generator node, n=1,2,...,N, G and Q represent the number of synchronous generators and renewable energy units under the nth generator node, respectively, S g and S q They represent the capacity of the g-th synchronous generator and the q-th new energy unit, respectively. g is the inertia time constant of the g-th synchronous generator.

[0099] Step 4: Calculate the inertia of other network nodes in the power system by the following formula:

[0100]

[0101] Among them, H m is the inertia of the mth other network node, m=1,2,...,M, B nm is the susceptance between the nth generator node and the mth other network node in the augmented admittance matrix, r mn is the element in the matrix R corresponding to the voltage relationship between the mth other network node and the nth generator node. The matrix R is U e and U net The correlation matrix between net =RU e And there is

[0102] Step 5: Determine whether the minimum inertia of other network nodes in the power system is greater than the critical inertia of the power system based on the frequency change rate constraint. Critical inertia of power system under the constraint of maximum frequency deviation

[0103] If yes, it means that the power system has strong frequency stability at this time, and there is no need to consider the inertia-constrained SVG site selection and sizing, and then execute step 7; otherwise, execute step 6.

[0104] Step 6: Calculate the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node:

[0105]

[0106] Among them, H min is the minimum inertia value of other network nodes, and the serial number of other network nodes corresponding to the minimum inertia value of other network nodes is recorded as x, x = 1, 2, ..., M; B nx is the susceptance between the nth generator node and the xth other network node in the augmented admittance matrix, r xn is the element in the matrix R corresponding to the voltage relationship between the xth other network node and the nth generator node.

[0107] Configure the grid-type SVG at the generator node with the highest sensitivity to increase the overall inertia of the system, update the line parameters and unit parameters of the power system, and then return to step 2.

[0108] Step 7: Calculate the short-circuit ratio MESCR of the access point of the new energy station according to the following formula G And the short circuit ratio of the new energy station and grid connection point MESCR S :

[0109]

[0110] Among them, MESCR r is the short-circuit ratio at the rth access point / grid connection point of the new energy station, U Nr is the nominal voltage of the rth access point / grid connection point of the new energy station, U REr I is the voltage generated by the power generated by the new energy equipment / station at the rth access point / grid connection point, r and I e are the short-circuit currents provided to the rth and eth access points / grid-connected points, W is the total number of access points / grid-connected points, and Z eqrr Z eq The r-th row and r-th column element of Z eqre Z eq The rth row and eth column element of Z eq is the AC grid equivalent impedance matrix at the rth access point / grid connection point of the new energy station, and Z eq and the augmented admittance matrix Y s are inverse matrices of each other.

[0111] Step 8: Determine whether the access point short circuit ratio is greater than the access point critical short circuit ratio, if yes, execute step 9, otherwise execute step 10.

[0112] Step 9: Determine whether the short-circuit ratio of the grid-connected point is greater than the critical short-circuit ratio of the grid-connected point. If so, it means that the power system does not need to be configured with SVG, otherwise, execute step 10.

[0113] Step 10: Configure a meshing type SVG at the grid-connected bus node with the smallest short-circuit ratio among the access point and the grid-connected point, recalculate the augmented admittance matrix, and then return to step 7.

[0114] In step ten, the short-circuit ratio of the access point of the new energy station and the short-circuit ratio of the grid-connected point of the new energy station are recalculated until both the short-circuit ratio of the access point and the short-circuit ratio of the grid-connected point meet the critical requirements, indicating that the power system has good voltage stability at this time and can avoid the occurrence of transient overvoltage phenomena.

[0115] This implementation method uses a two-stage meshed SVG site selection and capacity determination method to enable the system to simultaneously meet the system voltage support strength and frequency support strength, thereby ensuring stable operation of the system after a disturbance occurs.

[0116] Specific implementation method 2: The network-type SVG site selection and volume determination device described in this implementation method includes:

[0117] Critical inertia calculation unit: reads the grid structure, line parameters and unit parameters of the power system, and calculates the system critical inertia considering the maximum frequency deviation and frequency change rate according to the power disturbance of the power system.

[0118] The rate of change of frequency of the power system RoCoF is an important indicator to measure the frequency safety and stability of the system after a disturbance occurs, and its size mainly depends on the system inertia level. The maximum frequency change rate after the system is disturbed is proportional to the disturbance power and inversely proportional to the inertia size. The larger the disturbance power and the lower the system inertia, the easier it is to trigger the protection action. The frequency does not change at the moment of the disturbance, and the frequency regulation effect of the generator and load in the system does not work. The frequency change only depends on the size of the system inertia and the disturbance power. Critical inertia of power system based on frequency change rate constraint for:

[0119]

[0120] Among them, ΔP max is the maximum disturbance power, RoCoF max is the maximum frequency change rate of the power system.

[0121] When the maximum disturbance power ΔP occurs in the system max In order to make the center of inertia RoCoF not exceed the threshold RoCoF max , the power system inertia should be greater than

[0122] Without considering the frequency regulation of generators and loads, the maximum frequency deviation mainly depends on the inertia level and primary frequency regulation capability. The greater the inertia level and primary frequency regulation capability of the power system, the smaller the maximum frequency deviation of the system after the disturbance occurs. In order to ensure that the frequency deviation is within the safety constraint range, In order to avoid collapse, the system should have sufficient inertia level to cope with various disturbances; the system frequency deviation depends on the initial power shortage and system inertia, and has a linear relationship with time. According to the frequency response model of the multi-machine system, the critical inertia of the power system under the maximum frequency deviation constraint of the power system is derived. The expression is:

[0123]

[0124] Among them, f B is the reference frequency, t nadir is the moment when the lowest frequency point occurs, is the maximum frequency deviation of the power system.

[0125] It can be seen that in a power system with low inertia, RoCoF max and In summary, the boundary inertia level that satisfies these two indicators within the safe range after the disturbance is the critical inertia considering the frequency stability constraint.

[0126] Augmented admittance matrix calculation unit: The augmented admittance matrix of the power system is obtained using the line parameters and unit parameters of the power system.

[0127] Assuming that there are N+M nodes in a power system, including N generator nodes and M other network nodes, the augmented admittance matrix Y of the power system is s The expression is:

[0128]

[0129] Among them, Y N is the diagonal array formed after the transient reactance of the generator is converted into admittance, Y NN and Y MM are the self-admittances of the generator node and other network nodes, Y lN and Y lM are the equivalent admittances of the loads at the generator nodes and other network nodes after being simplified to equivalent admittances, Y NM and Y MN are the mutual admittances of the generator node and other network nodes respectively, and the conductance is neglected.

[0130] The network equation of the power system is:

[0131]

[0132] Among them, I n U is the current input from the potential node in the generator to the network; e and U net are the voltages of the generator node and other network nodes respectively; Y 1 , Y 2 , Y 3 , Y 4 They are the augmented admittance matrices Y s of four regions, including:

[0133] Y 1 =Y N , Y 2 =[-Y N 0]、

[0134] Inertia calculation unit of generator node:

[0135] The inertia of the generator node in the power system is calculated by the following formula:

[0136]

[0137] Among them, H n is the inertia of the nth generator node, n=1,2,...,N, G and Q represent the number of synchronous generators and renewable energy units under the nth generator node, respectively, S g and S q They represent the capacity of the g-th synchronous generator and the q-th new energy unit, respectively. g is the inertia time constant of the g-th synchronous generator.

[0138] Inertia calculation unit of other network nodes:

[0139] The inertia of other network nodes in the power system is calculated by the following formula:

[0140]

[0141] Among them, H m is the inertia of the mth other network node, m=1,2,...,M, B nm is the susceptance between the nth generator node and the mth other network node in the augmented admittance matrix, r mn is the element in the matrix R corresponding to the voltage relationship between the mth other network node and the nth generator node. The matrix R is U e and U net The correlation matrix betweennet =RU e And there is

[0142] Inertia judgment unit: judge whether the minimum inertia of other network nodes in the power system is greater than the critical inertia of the power system based on the frequency change rate constraint Critical inertia of power system under the constraint of maximum frequency deviation

[0143] Sensitivity calculation unit: When the minimum inertia of other network nodes in the power system is less than the critical inertia of the power system, the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node is calculated:

[0144]

[0145] Among them, H min is the minimum inertia value of other network nodes, and the serial number of other network nodes corresponding to the minimum inertia value of other network nodes is recorded as x, x = 1, 2, ..., M; B nx is the susceptance between the nth generator node and the xth other network node in the augmented admittance matrix, r xn is the element in the matrix R corresponding to the voltage relationship between the xth other network node and the nth generator node.

[0146] Then, a meshed SVG is configured at the generator node with the highest sensitivity to increase the overall inertia of the system.

[0147] Short-circuit ratio calculation unit: When the minimum inertia of other network nodes in the power system is greater than the critical inertia of the power system, it means that the power system has strong frequency stability at this time, and there is no need to consider the site selection and sizing of the grid-forming SVG with inertia constraints.

[0148] Calculate the short-circuit ratio MESCR of the access point of the new energy station according to the following formula G And the short circuit ratio of the new energy station and grid connection point MESCR S :

[0149]

[0150] Among them, MESCR r is the short-circuit ratio at the rth access point / grid connection point of the new energy station, U Nr is the nominal voltage of the rth access point / grid connection point of the new energy station, U REr I is the voltage generated by the power generated by the new energy equipment / station at the rth access point / grid connection point, r and I e are the short-circuit currents provided to the rth and eth access points / grid-connected points, W is the total number of access points / grid-connected points, and Zeqrr Z eq The r-th row and r-th column element of Z eqre Z eq The rth row and eth column element of Z eq is the AC grid equivalent impedance matrix at the rth access point / grid connection point of the new energy station, and Z eq and the augmented admittance matrix Y s are inverse matrices of each other.

[0151] Access point short circuit ratio judgment unit: judges whether the short circuit ratio of the access point of the new energy station is greater than the critical short circuit ratio of the access point.

[0152] Grid connection point short circuit ratio judgment unit: When the short circuit ratio of the new energy station access point is greater than the critical short circuit ratio of the access point, and the short circuit ratio of the new energy station grid connection point is greater than the critical short circuit ratio of the grid connection point, it means that the current power system does not need to be configured with SVG.

[0153] Configuration unit: When the short-circuit ratio of the access point of the new energy site is less than the critical short-circuit ratio of the access point, a meshing type SVG is configured at the grid-connected bus node with the smallest short-circuit ratio.

[0154] Specific implementation method three: This implementation method describes a computer-readable storage medium, wherein the storage medium stores a computer program, and is characterized in that when the computer program is executed, the method described in specific implementation method one is implemented.

[0155] Specific implementation mode 4: The electronic device described in this implementation mode includes a storage medium, a processor, and a computer program stored in the storage medium and executable on the processor, wherein the processor executes the computer program to implement the method described in specific implementation mode 1.

[0156] Example

[0157] In order to verify the practicability of the method of the present invention, an improved WSCC9 node example system is used for verification. Figure 2 As shown in the figure, the inertia time constants of generators G1, G2, and G3 are 6.4s, 3.01s, and 23.64s respectively. Wind turbines with capacities of 100MW, 100MW, and 50MW are connected to generators G1, G2, and G3 respectively in an external manner, and the system wind turbine penetration rate is 30.49%. Set the load of node 2 to increase by 90MW. The base frequency is 50Hz, and RoCoF max =0.15Hz / s, maximum allowable frequency deviation The critical inertia of the system stability under the maximum frequency change rate and maximum deviation constraints is 17.9s, the critical short-circuit ratio of the grid connection point is 2, and the critical short-circuit ratio of the access point is 1.5. The inertia time constant of the configured grid-type SVG is 7s and the capacity is 50MVar.

[0158] Under the above working conditions, the critical inertia H of the system is calculated by the limit values ​​of the maximum frequency change rate and the maximum frequency deviation. min , according to the system related parameters, calculate the node inertia and evaluate the system inertia distribution. Find the minimum inertia node as node 5, the minimum inertia is 9.96s, which is less than the minimum critical inertia H min . Then you need to configure the mesh type SVG. By calculating the sensitivity of the minimum inertia node inertia to the inertia of each generator node, such as Figure 3 The sensitivity of the inertia of the 9 nodes in the WSCC9-node system to the inertia of the 3 generator nodes is used to find the configuration position where the minimum inertia node sensitivity is dominant; Table 1 shows that the minimum inertia node before configuration is node 5, and the generator node with the best inertia sensitivity for node 5 is node 8. After configuring the meshing type SVG at node 8, a new node inertia is obtained, and so on until the minimum inertia node is greater than the critical inertia of the system, and the meshing type SVG site selection and capacity determination considering the inertia limitation is ended. The inertia of each node in the system before and after the meshing type SVG configuration is shown in Table 1.

[0159] Table 1 Inertia of each node before and after the configuration of the mesh type SVG

[0160]

[0161] The results of the meshing SVG configuration are shown in Table 2. It is necessary to configure two meshing SVGs at generator node 8 and one meshing SVG at generator node 7, for a total of three meshing SVGs with a total capacity of 150 Mvar.

[0162] Table 2 Site selection and capacity determination strategy for grid-type SVG considering inertia constraints

[0163]

[0164] The short circuit ratio of each new energy access point and the short circuit ratio of the new energy grid connection point are calculated as shown in Table 3. The short circuit ratio of the new energy access point at nodes 7 and 8 is less than the critical value. It is necessary to configure the network-type SVG at the node with the smallest short circuit ratio. After configuration, recalculate the short circuit ratio of each new energy access point and the short circuit ratio of the new energy grid connection point. This is repeated until the short circuit ratio of the smallest new energy access point is greater than 1.5 and the short circuit ratio of the smallest new energy grid connection point is greater than 2, and the site selection and capacity determination of the network-type SVG considering the short circuit ratio restriction is terminated.

[0165] Table 3 Short-circuit ratio of each new energy access point and new energy grid connection point before SVG configuration

[0166]

[0167] The results of the mesh-type SVG configuration are shown in Table 4. It is necessary to configure 2 mesh-type SVGs at generator node 7 and 2 mesh-type SVGs at generator node 8, for a total of 4 mesh-type SVGs with a total capacity of 200 Mvar.

[0168] Table 4. Site selection and capacity determination strategy for network-based SVG considering short-circuit ratio constraints

[0169]

[0170] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. A method for selecting and determining the location and volume of a network-based SVG, characterized in that: include: The augmented admittance matrix of the power system is obtained by using the line parameters and unit parameters of the power system. Based on the augmented admittance matrix, respectively calculate the inertia of the generator node and other network nodes in the power system; Determine whether the minimum inertia of other network nodes in the power system is greater than the critical inertia of the power system. If so, calculate the short-circuit ratio of the access point of the new energy station and the short-circuit ratio of the grid connection point respectively. Otherwise, calculate the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node, and configure the network-type SVG at the generator node with the highest sensitivity. Determine whether the short-circuit ratios of the new energy station access point and the grid-connected point are both greater than their respective critical short-circuit ratios. If so, it means that the current power system does not need to configure SVG. Otherwise, configure a grid-connected SVG at the grid-connected bus node with the smallest short-circuit ratio.

2. The method for selecting a site and determining the volume of a network-based SVG according to claim 1, wherein: The method of obtaining an augmented admittance matrix of the power system by using line parameters and unit parameters of the power system includes: Assume that the power system has a total of N+M nodes, including N generator nodes and M other network nodes, then the augmented admittance matrix Y of the power system is s The expression is: Among them, Y N is the diagonal array formed after the transient reactance of the generator is converted into admittance, Y NN and Y MM are the self-admittances of the generator node and other network nodes, Y lN and Y lM are the equivalent admittances of the loads at the generator nodes and other network nodes after being simplified to equivalent admittances, Y NM and Y MN are the mutual admittances of the generator node and other network nodes respectively.

3. The method for selecting a site and determining the volume of a network-based SVG according to claim 2, wherein: The method of calculating the inertia of the generator node and other network nodes in the power system based on the augmented admittance matrix includes: The inertia of the generator node in the power system is calculated by the following formula: Among them, H n is the inertia of the nth generator node, n=1,2,...,N, G and Q represent the number of synchronous generators and renewable energy units under the nth generator node, respectively, S g and S q They represent the capacity of the g-th synchronous generator and the q-th new energy unit, respectively. g is the inertia time constant of the g-th synchronous generator; The inertia of other network nodes in the power system is calculated by the following formula: Among them, H m is the inertia of the mth other network node, m=1,2,...,M, B nm is the susceptance between the nth generator node and the mth other network node in the augmented admittance matrix, r mn is the element in the matrix R corresponding to the voltage relationship between the mth other network node and the nth generator node. The matrix R is U e and U net The correlation matrix between U e and U net are the voltages of the generator node and other network nodes, and U net =RU e .

4. The method for selecting a site and determining the volume of a network-based SVG according to claim 1, wherein: The critical inertia of the power system includes: the critical inertia of the power system based on the frequency change rate constraint and the critical inertia of the power system based on the maximum frequency deviation constraint; When the minimum node inertia is greater than the critical inertia of the power system based on the frequency change rate constraint and the critical inertia of the power system based on the maximum frequency deviation constraint, the short-circuit ratio of the new energy station access point and the short-circuit ratio of the grid connection point are calculated respectively; otherwise, the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node is calculated, and the meshing type SVG is configured at the generator node with the highest sensitivity.

5. The method for selecting a site and determining the volume of a network-based SVG according to claim 4, characterized in that: The critical inertia of the power system based on the frequency change rate constraint The expression is: Among them, ΔP max is the maximum disturbance power, RoCoF max is the maximum frequency change rate of the power system; The critical inertia of the power system based on the maximum frequency deviation constraint The expression is: Among them, f B is the reference frequency, t nadir is the moment when the lowest frequency point occurs, is the maximum frequency deviation of the power system.

6. The method for selecting a site and determining the volume of a network-based SVG according to claim 3, characterized in that: The calculation of the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node includes: Among them, H min is the minimum inertia value of other network nodes, and the serial number of other network nodes corresponding to the minimum inertia value of other network nodes is recorded as x, x = 1, 2, ..., M; B nx is the susceptance between the nth generator node and the xth other network node in the augmented admittance matrix, r xn is the element in the matrix R corresponding to the voltage relationship between the xth other network node and the nth generator node.

7. The method for selecting a site and determining the volume of a network-based SVG according to claim 1, wherein: The respectively calculating the short-circuit ratio of the access point of the new energy station and the short-circuit ratio of the grid connection point includes: Among them, MESCR r is the short-circuit ratio at the rth access point / grid connection point of the new energy station, U Nr is the nominal voltage of the rth access point / grid connection point of the new energy station, U REr I is the voltage generated by the power generated by the new energy equipment / station at the rth access point / grid connection point, r and I e are the short-circuit currents provided to the rth and eth access points / grid-connected points, W is the total number of access points / grid-connected points, and Z eqrr Z eq The r-th row and r-th column element of Z eqre Z eq The rth row and eth column element of Z eq is the AC grid equivalent impedance matrix at the rth access point / grid connection point of the new energy station, and Z eq and the augmented admittance matrix Y s are inverse matrices of each other.

8. A network-type SVG site selection and volume determination device, characterized in that: include: Augmented admittance matrix calculation unit: using the line parameters and unit parameters of the power system to obtain the augmented admittance matrix of the power system; Inertia calculation unit: calculates the inertia of the generator node and other network nodes in the power system respectively based on the augmented admittance matrix; Inertia judgment unit: judge whether the minimum inertia of other network nodes in the power system is greater than the critical inertia of the power system; Sensitivity calculation unit: when the minimum inertia of other network nodes in the power system is less than the critical inertia of the power system, the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node is calculated, and the meshing type SVG is configured at the generator node with the highest sensitivity; Short-circuit ratio calculation unit: when the minimum inertia of other network nodes in the power system is greater than the critical inertia of the power system, the short-circuit ratio of the new energy station access point and the short-circuit ratio of the grid connection point are calculated respectively; Short-circuit ratio judgment unit: judge whether the short-circuit ratios of the access point and the grid connection point of the new energy station are both greater than their respective critical short-circuit ratios. When the short-circuit ratios of the access point and the grid connection point of the new energy station are both greater than their respective critical short-circuit ratios, it means that the current power system does not need to configure SVG. Otherwise, a grid-forming SVG is configured at the grid-connected bus node with the smallest short-circuit ratio.

9. The network-type SVG site selection and volume determination device according to claim 8, characterized in that: The method of obtaining an augmented admittance matrix of the power system by using line parameters and unit parameters of the power system includes: Assume that the power system has a total of N+M nodes, including N generator nodes and M other network nodes, then the augmented admittance matrix Y of the power system is s The expression is: Among them, Y N is the diagonal array formed after the transient reactance of the generator is converted into admittance, Y NN and Y MM are the self-admittances of the generator node and other network nodes, Y lN and Y lM are the equivalent admittances of the loads at the generator nodes and other network nodes after being simplified to equivalent admittances, Y NM and Y MN are the mutual admittances of the generator node and other network nodes respectively.

10. The network-type SVG site selection and volume determination device according to claim 9, characterized in that: The method of calculating the inertia of the generator node and other network nodes in the power system based on the augmented admittance matrix includes: The inertia of the generator node in the power system is calculated by the following formula: Among them, H n is the inertia of the nth generator node, n=1,2,...,N, G and Q represent the number of synchronous generators and renewable energy units under the nth generator node, respectively, S g and S q They represent the capacity of the g-th synchronous generator and the q-th new energy unit, respectively. g is the inertia time constant of the g-th synchronous generator; The inertia of other network nodes in the power system is calculated by the following formula: Among them, H m is the inertia of the mth other network node, m=1,2,...,M, B nm is the susceptance between the nth generator node and the mth other network node in the augmented admittance matrix, r mn is the element in the matrix R corresponding to the voltage relationship between the mth other network node and the nth generator node. The matrix R is U e and U net The correlation matrix between U e and U net are the voltages of the generator node and other network nodes, and U net =RU e .

11. The network-type SVG site selection and volume determination device according to claim 8, characterized in that: The critical inertia of the power system includes: the critical inertia of the power system based on the frequency change rate constraint and the critical inertia of the power system based on the maximum frequency deviation constraint; When the minimum node inertia is greater than the critical inertia of the power system based on the frequency change rate constraint and the critical inertia of the power system based on the maximum frequency deviation constraint, the short-circuit ratio of the new energy station access point and the short-circuit ratio of the grid connection point are calculated respectively. Otherwise, the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node is calculated, and the meshing type SVG is configured at the generator node with the highest sensitivity.

12. The network-type SVG site selection and volume determination device according to claim 11, characterized in that: The critical inertia of the power system based on the frequency change rate constraint The expression is: Among them, ΔP max is the maximum disturbance power, RoCoF max is the maximum frequency change rate of the power system; The critical inertia of the power system based on the maximum frequency deviation constraint The expression is: Among them, f B is the reference frequency, t nadir is the moment when the lowest frequency point occurs, is the maximum frequency deviation of the power system.

13. The network-type SVG site selection and volume determination device according to claim 10, characterized in that: The calculation of the sensitivity of the minimum inertia of other network nodes to the inertia of each generator node includes: Among them, H min is the minimum inertia value of other network nodes, and the serial number of other network nodes corresponding to the minimum inertia value of other network nodes is recorded as x, x = 1, 2, ..., M; B nx is the susceptance between the nth generator node and the xth other network node in the augmented admittance matrix, r xn is the element in the matrix R corresponding to the voltage relationship between the xth other network node and the nth generator node.

14. The network-type SVG site selection and volume determination device according to claim 8, characterized in that: The respectively calculating the short-circuit ratio of the access point of the new energy station and the short-circuit ratio of the grid connection point includes: Among them, MESCR r is the short-circuit ratio at the rth access point / grid connection point of the new energy station, U Nr is the nominal voltage of the rth access point / grid connection point of the new energy station, U REr I is the voltage generated by the power generated by the new energy equipment / station at the rth access point / grid connection point, r and I e are the short-circuit currents provided to the rth and eth access points / grid-connected points, W is the total number of access points / grid-connected points, and Z eqrr Z eq The r-th row and r-th column element of Z eqre Z eq The rth row and eth column element of Z eq is the AC grid equivalent impedance matrix at the rth access point / grid connection point of the new energy station, and Z eq and the augmented admittance matrix Y s are inverse matrices of each other.

15. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed, the method according to any one of claims 1 to 7 is implemented.

16. An electronic device comprising a storage medium, a processor, and a computer program stored in the storage medium and executable on the processor, characterized in that: The processor executes the computer program to implement the method according to any one of claims 1 to 7.

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