Energy storage optimal configuration method and system for improving new energy multi-station short-circuit ratio

Abstract

The invention discloses an energy storage optimal configuration method and system for improving the short-circuit ratio of multiple new energy stations, and the method comprises the steps: building a power grid simulation digital model comprising a plurality of new energy stations, and determining the selected range of the new energy stations; calculating the short-circuit ratio of each new energy station in the selected range; determining the capacity configuration and access position scheme of energy storage which can be accessed by each new energy station; based on the short-circuit ratio, the energy storage capacity configuration and the access position scheme of each new energy station, determining an energy storage configuration scheme of each new energy station meeting the short-circuit ratio requirement; based on the power grid security constraint, determining an energy storage configuration scheme meeting the power grid security constraint; and determining an energy storage configuration scheme meeting the economical efficiency requirement based on the economical efficiency requirement objective function.

Description

Technical Field

[0001] The present invention relates to the technical field of distributed renewable energy power generation in power systems, and more specifically, to an energy storage optimization configuration method and system for improving the short-circuit ratio of multiple renewable energy stations. Background Art

[0002] The structure of the power system shows a trend of a high proportion of new energy. As the scale of new energy grid connection continues to increase, it has brought new changes to the operating characteristics of the power grid, especially the problem of voltage stability has gradually become prominent. However, new energy resources such as wind and light are subject to environmental constraints, resulting in intermittent and high uncertainty in their output, and it is difficult to maintain a balance between power generation and load. Not only does it affect the safe operation of the power grid, but it is also accompanied by wind and light abandonment, which to a certain extent restricts the development of new energy technologies. To solve this problem, energy storage devices are usually installed in the process of new energy grid connection to smooth out output fluctuations and reduce peaks and fill valleys.

[0003] Energy storage has the characteristics of high regulation accuracy, fast response speed, and flexible application. It can be applied to power peak regulation, frequency regulation, voltage regulation, and improving renewable energy absorption capacity. It also has unique active and reactive four-quadrant regulation capabilities and millisecond-level response capabilities, which can effectively control the system voltage and improve the voltage regulation capability and transient voltage stability of the power grid. At this important stage of energy storage development, it is of great significance to explore the impact of energy storage access on the system MRSCR.

[0004] Therefore, a technology is needed to achieve an optimized energy storage configuration solution for the short-circuit ratio of multiple renewable energy stations. Summary of the invention

[0005] The technical solution of the present invention provides a method and system for optimizing energy storage configuration for improving the short-circuit ratio of multiple renewable energy stations, so as to solve the problem of how to optimize energy storage configuration for improving the short-circuit ratio of multiple renewable energy stations.

[0006] In order to solve the above problems, the present invention provides a method for optimizing energy storage configuration for improving the short-circuit ratio of multiple renewable energy stations, the method comprising:

[0007] Establish a digital model of power grid simulation that includes multiple new energy stations and determine the selection range of new energy stations;

[0008] Calculate the short-circuit ratio of each new energy station within the selected range;

[0009] Determine the capacity configuration and access location plan of energy storage that can be connected to each new energy station;

[0010] Based on the short-circuit ratio of each new energy station, the capacity configuration of energy storage and the access location plan, determine the energy storage configuration plan for each new energy station that meets the short-circuit ratio requirements;

[0011] Based on grid security constraints, determine the energy storage configuration scheme that meets grid security constraints;

[0012] Based on the economic requirement objective function, determine the energy storage configuration plan that meets the economic requirements.

[0013] Preferably, the establishment of a power grid simulation digital model including a plurality of new energy stations includes a power grid component model, equipment operation limit parameters and new energy station model parameters, wherein:

[0014] The grid element model includes transmission line parameters, transformer parameters, generator node parameters, load node parameters, and generator and spare capacity data; the transmission line parameters include resistance, reactance, conductance, and susceptance; the transformer parameters include leakage reactance, transformation ratio, and tap position; the generator node parameters include active and reactive output values; the load node parameters include active and reactive values;

[0015] The equipment operation limit parameters include: line rated current, transformer rated capacity, and generator maximum output; the generator maximum output includes: active maximum output and reactive maximum output;

[0016] The new energy station model parameters include: bus node information, line information and transformer information; the bus node information includes: node name, node type, reference voltage, node zone, maximum active output of new energy units, and actual active output of new energy units; the line information includes: line name, line rated current, resistance per unit value, reactance per unit value, and ground admittance, covering the connecting lines between each new energy unit and the collection station; the transformer information includes: transformer name, rated capacity, leakage reactance, and transformer tap position, covering the box transformer and step-up transformer of each new energy unit.

[0017] Preferably, the calculating the short circuit ratio of each new energy station within the selected range includes:

[0018] The equivalent impedance matrix expression of the AC power grid of the new energy grid-connected bus is:

[0019]

[0020] in, The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The m-th row and m-th column element of ;

[0021] The calculation formula for the short-circuit ratio of multiple renewable energy stations taking into account the mutual influence between multiple renewable energy stations is:

[0022]

[0023] in: is the nominal voltage of the mth grid-connected bus node; The short-circuit current provided for the mth new energy station; The short-circuit current provided for the nth new energy station; is the actual operating voltage of the mth grid-connected bus node; The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The element in the mth row and nth column of ; The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The mth row and mth column element of ; h is the number of grid-connected busbars.

[0024] Preferably, the determining of the capacity configuration and access location scheme of the energy storage that each new energy station can access includes:

[0025] Assume that the i-th new energy station needs to be connected to energy storage, denoted as X i ,X i =0 or 1, 0 means no energy storage is connected, 1 means energy storage is connected, and the energy storage that each new energy station needs to connect to is X = [X 1 ,X 2 ,...,X n ];

[0026] Assume that the accessible capacity of energy storage is S = [S 1 ,S 2 ,...,S k ], where S 1 , S 2 , ..., S k is the number of grid-connected busbars;

[0027] Then the energy storage capacity configuration plan of the i-th new energy station is:

[0028] D i =X i,1 *S 1 +X i,2 *S 2 +...+X i,k *S k , X i,k =0 or 1 (3)

[0029] Among them, D i The total capacity of energy storage configured for the i-th new energy station; X i,k Is the i-th new energy station configured with a capacity of S k Energy storage, X i,k The value is 0 or 1.

[0030] Preferably, the method of determining the energy storage configuration scheme of each new energy station that meets the short circuit ratio requirement based on the short circuit ratio of each new energy station and the capacity configuration and access location scheme of the energy storage includes:

[0031] S1: When there are multiple new energy stations with short circuit ratio Less than the minimum short-circuit ratio M MRSCR(min) When the short circuit ratio is selected The smallest new energy station is connected to energy storage;

[0032] S2: Determine whether the different capacity energy storage configuration schemes generated for the connected new energy stations meet the short-circuit ratio Greater than the minimum short-circuit ratio M MRSCR(min) Configuration scheme;

[0033] S3: When there is a short circuit ratio Greater than the minimum short-circuit ratio M MRSCR(min) If there is no configuration scheme that satisfies the short-circuit ratio, the configuration scheme is retained; Greater than the minimum short-circuit ratio M MRSCR(min) When the configuration scheme is selected, the short circuit ratio Improve the configuration scheme with the largest size;

[0034] S4: Recalculate the short-circuit ratio of the new energy stations and repeat S1-S4 until the short-circuit ratio of all new energy stations is Both are greater than M MRSCR(min) until.

[0035] Preferably, based on the grid security constraint, an energy storage configuration scheme satisfying the grid security constraint is determined, wherein the grid security constraint includes: short-circuit current and voltage offset constraints;

[0036] Evaluate the short-circuit current of the energy storage system after adding energy storage, and determine whether the short-circuit current exceeds the short-circuit current threshold: the energy storage is equivalent to a controlled current source. When the voltage continues to drop after a short circuit, the low-voltage control enables the energy storage system to continue to operate without disconnecting from the grid, and the reactive support is increased by energy storage to restore the voltage at the grid connection point; when the grid fails, the energy storage system is equivalent to a current source as an equivalent model of the energy storage system in the short-circuit current calculation. The output current of the energy storage system is:

[0037] I c =K bat K.I N (4)

[0038] Among them, K is the allowable overcurrent multiple, ranging from 1.2 to 1.5; K bat is the output current coefficient of different batteries, I N is the rated output current of the energy storage system;

[0039] When a three-phase short circuit fault occurs at a certain point in the energy storage system, for a normal network, it is equivalent to adding an injection current at the fault point k. The voltage at any point i in the network is expressed as:

[0040]

[0041] Among them, G is the set of active nodes in the network; Z ij is the mutual impedance between the ij nodes; is the injected current of node j; Z ik is the impedance of fault point k; j is node j;

[0042] Any node voltage consists of two voltage superpositions. The first is the normal component of the node voltage before the short circuit. The second is when the three-phase voltage source in the network is short-circuited and the equivalent current source is open-circuited. The voltage generated at node k is also the fault component of the node voltage. The voltage at the fault point is obtained by superimposing the two voltages. For the fault point, the circuit current at the fault point is obtained by combining the boundary conditions of the fault point:

[0043]

[0044] in, is the fault point voltage; Z f is the grounding resistance at the fault point; is the normal component of the node voltage before short circuit; Z kk is the self-impedance of the k-node;

[0045] The three-phase quantity generated by the asymmetric fault is decomposed into positive, negative and zero sequence, and the three-sequence network equation is established. Then, according to the superposition principle, the boundary conditions are established to solve the short-circuit current of each sequence network, where the network equation of each sequence network is:

[0046]

[0047] in, are the positive sequence voltage, negative sequence voltage and zero sequence voltage of the fault port respectively; is the external voltage source voltage; are the sequence components of the fault current injected by the power supply to the fault point respectively; are the equivalent impedance matrices of each sequence network respectively; to are the positive sequence network impedance respectively; to are the negative sequence network impedance respectively; to are zero-sequence network impedance respectively; m is the fault node; n is the number of nodes;

[0048] Set the boundary conditions for single-phase ground fault:

[0049]

[0050] Set the boundary conditions for a two-phase short-circuit fault:

[0051]

[0052] Boundary conditions of two-phase ground short circuit fault:

[0053]

[0054] The short-circuit current obtained from the symmetrical fault and asymmetrical fault of the network equation is combined with the constraints of the converter type power supply to obtain the energy storage system equation:

[0055]

[0056] in, It is the additional phase angle generated by the energy storage system to provide reactive power support for the AC system; U is the voltage of the energy storage system; I c is the output current of the energy storage power station; P ref is the energy storage power reference value; i qref is the reference value of the q-axis component on the AC side; I max is the maximum output current of the energy storage system;

[0057] Obtaining the output current of the energy storage power station through the voltage drop area Substitute them into the equations of different fault types to solve them, obtain the accurate sum of short-circuit currents provided by synchronous generators and energy storage power stations, and set the grid short-circuit current constraint as:

[0058] I D,j ≤I D,max (14)

[0059] Among them, I D,j is the short-circuit current of grid node j; I D,max It is the preset maximum allowable value of short-circuit current;

[0060] After the energy storage is connected to the grid, it needs to meet the voltage offset constraint range of the grid. The voltage offset constraint is set as:

[0061]

[0062] Among them, U N is the nominal voltage; U j is the voltage amplitude of grid node j; and They are the lower and upper limits of voltage deviation specified in the technical guidelines respectively;

[0063] Based on the voltage offset constraint range, the short-circuit current and voltage offset of each energy storage configuration scheme are calculated, and the configuration schemes that do not meet the short-circuit current and voltage offset constraints are removed to generate an energy storage configuration scheme that meets the grid safety constraints. 1 ,Φ 2 ,...,Φ p ]; where p is the number of configuration schemes that meet the grid security constraints.

[0064] Preferably, the determining of the energy storage configuration scheme that meets the economic requirements based on the economic requirements objective function includes:

[0065] The economic requirement objective function is:

[0066] minC i =min(X i,1 *c 1 +X i,2 *c 2 +...+X i,k *c k ) (16)

[0067] Among them, c 1 、c 2 …c k The total cost of configuring energy storage for the 1st, 2nd…kth new energy stations; X i，1 , X i，2 …X i，k The configuration capacity of the 1st, 2nd…kth new energy stations is S k The amount of energy stored, c k To configure the capacity to S k The cost of energy storage.

[0068] Based on another aspect of the present invention, the present invention provides an energy storage optimization configuration system for improving the short-circuit ratio of multiple new energy stations, the system comprising:

[0069] A power grid simulation digital model building unit is used to build a power grid simulation digital model including multiple new energy stations and determine the selection range of the new energy stations;

[0070] A new energy multi-station short-circuit ratio calculation unit, used to calculate the short-circuit ratio of each new energy station within a selected range;

[0071] The energy storage capacity configuration unit is used to determine the capacity configuration and access location plan of the energy storage that each new energy station can access;

[0072] A short circuit ratio constraint unit is used to determine the energy storage configuration plan of each new energy station that meets the short circuit ratio requirements based on the short circuit ratio of each new energy station, the capacity configuration of the energy storage and the access location plan;

[0073] A power grid security constraint unit, used to determine an energy storage configuration scheme that satisfies the power grid security constraints based on the power grid security constraints;

[0074] The economic constraint unit is used to determine the energy storage configuration scheme that meets the economic requirements based on the economic requirement objective function.

[0075] Preferably, the establishment of a power grid simulation digital model including a plurality of new energy stations includes a power grid component model, equipment operation limit parameters and new energy station model parameters, wherein:

[0076] The grid element model includes transmission line parameters, transformer parameters, generator node parameters, load node parameters, and generator and spare capacity data; the transmission line parameters include resistance, reactance, conductance, and susceptance; the transformer parameters include leakage reactance, transformation ratio, and tap position; the generator node parameters include active and reactive output values; the load node parameters include active and reactive values;

[0077] The equipment operation limit parameters include: line rated current, transformer rated capacity, and generator maximum output; the generator maximum output includes: active maximum output and reactive maximum output;

[0078] The new energy station model parameters include: bus node information, line information and transformer information; the bus node information includes: node name, node type, reference voltage, node zone, maximum active output of new energy units, and actual active output of new energy units; the line information includes: line name, line rated current, resistance per unit value, reactance per unit value, and ground admittance, covering the connecting lines between each new energy unit and the collection station; the transformer information includes: transformer name, rated capacity, leakage reactance, and transformer tap position, covering the box transformer and step-up transformer of each new energy unit.

[0079] Preferably, the calculating the short circuit ratio of each new energy station within the selected range includes:

[0080] The equivalent impedance matrix expression of the AC power grid of the new energy grid-connected bus is:

[0081]

[0082] in, The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The m-th row and m-th column element of ;

[0083] The calculation formula for the short-circuit ratio of multiple renewable energy stations taking into account the mutual influence between multiple renewable energy stations is:

[0084]

[0085] in: is the nominal voltage of the mth grid-connected bus node; The short-circuit current provided for the mth new energy station; The short-circuit current provided for the nth new energy station; is the actual operating voltage of the mth grid-connected bus node; The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The element in the mth row and nth column of ; The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The mth row and mth column element of ; h is the number of grid-connected busbars.

[0086] Preferably, the determining of the capacity configuration and access location scheme of the energy storage that each new energy station can access includes:

[0087] Assume that the i-th new energy station needs to be connected to energy storage, denoted as X i ,X i =0 or 1, 0 means no energy storage is connected, 1 means energy storage is connected, and the energy storage that each new energy station needs to connect to is X = [X 1 ,X 2 ,...,X n ];

[0088] Assume that the accessible capacity of energy storage is S = [S 1 ,S 2 ,...,S k ], where S 1 , S 2 , ..., S k The capacity of the access storage;

[0089] Then the energy storage capacity configuration plan of the i-th new energy station is:

[0090] D i =X i,1 *S 1 +X i,2 *S 2 +...+X i,k *S k , X i,k =0 or 1 (3)

[0091] Among them, D i The total capacity of energy storage configured for the i-th new energy station; X i,k Is the i-th new energy station configured with a capacity of S k Energy storage, X i,k The value is 0 or 1.

[0092] Preferably, the method of determining the energy storage configuration scheme of each new energy station that meets the short circuit ratio requirement based on the short circuit ratio of each new energy station and the capacity configuration and access location scheme of the energy storage includes:

[0093] S1: When there are multiple new energy stations with short circuit ratio Less than the minimum short-circuit ratio M MRSCR(min) When the short circuit ratio is selected The smallest new energy station is connected to energy storage;

[0094] S2: Determine whether the different capacity energy storage configuration schemes generated for the connected new energy stations meet the short-circuit ratio Greater than the minimum short-circuit ratio M MRSCR(min) Configuration scheme;

[0095] S3: When there is a short circuit ratio Greater than the minimum short-circuit ratio M MRSCR(min) If there is no configuration scheme that satisfies the short-circuit ratio, the configuration scheme is retained; Greater than the minimum short-circuit ratio M MRSCR(min) When the configuration scheme is selected, the short circuit ratio Improve the configuration scheme with the largest size;

[0096] S4: Recalculate the short-circuit ratio of the new energy stations and repeat S1-S4 until the short-circuit ratio of all new energy stations is Both are greater than M MRSCR(min) until.

[0097] Preferably, based on the grid security constraint, an energy storage configuration scheme satisfying the grid security constraint is determined, wherein the grid security constraint includes: short-circuit current and voltage offset constraints;

[0098] Evaluate the short-circuit current of the energy storage system after adding energy storage, and determine whether the short-circuit current exceeds the short-circuit current threshold: the energy storage is equivalent to a controlled current source. When the voltage continues to drop after a short circuit, the low-voltage control enables the energy storage system to continue to operate without disconnecting from the grid, and the reactive support is increased by energy storage to restore the voltage at the grid connection point; when the grid fails, the energy storage system is equivalent to a current source as an equivalent model of the energy storage system in the short-circuit current calculation. The output current of the energy storage system is:

[0099] I c =K bat K.I N (4)

[0100] Among them, K is the allowable overcurrent multiple, ranging from 1.2 to 1.5; K bat is the output current coefficient of different batteries, I N is the rated output current of the energy storage system;

[0101] When a three-phase short circuit fault occurs at a certain point in the energy storage system, for a normal network, it is equivalent to adding an injection current at the fault point k. The voltage at any point i in the network is expressed as:

[0102]

[0103] Among them, G is the set of active nodes in the network; Z ij is the mutual impedance between the ij nodes; is the injected current of node j; Z ik is the impedance of fault point k; j is the node;

[0104] Any node voltage consists of two voltage superpositions. The first is the normal component of the node voltage before the short circuit. The second is when the three-phase voltage source in the network is short-circuited and the equivalent current source is open-circuited. The voltage generated at node k is also the fault component of the node voltage. The voltage at the fault point is obtained by superimposing the two voltages. For the fault point, the circuit current at the fault point is obtained by combining the boundary conditions of the fault point:

[0105]

[0106] in, is the fault point voltage; Z f is the grounding resistance at the fault point; is the normal component of the node voltage before short circuit; Z kk is the self-impedance of the k-node;

[0107] The three-phase quantity generated by the asymmetric fault is decomposed into positive, negative and zero sequence, and the three-sequence network equation is established. Then, according to the superposition principle, the boundary conditions are established to solve the short-circuit current of each sequence network, where the network equation of each sequence network is:

[0108]

[0109] in, are the positive sequence voltage, negative sequence voltage and zero sequence voltage of the fault port respectively; is the external voltage source voltage; are the sequence components of the fault current injected by the power supply to the fault point respectively; are the equivalent impedance matrices of each sequence network respectively; to are the positive sequence network impedance respectively; to are the negative sequence network impedance respectively; to are zero-sequence network impedance respectively; m is the fault node; n is the number of nodes;

[0110] Set the boundary conditions for single-phase ground fault:

[0111]

[0112] Set the boundary conditions for a two-phase short-circuit fault:

[0113]

[0114] Boundary conditions of two-phase ground short circuit fault:

[0115]

[0116] The short-circuit current obtained from the symmetrical fault and asymmetrical fault of the network equation is combined with the constraints of the converter type power supply to obtain the energy storage system equation:

[0117]

[0118] in, It is the additional phase angle generated by the energy storage system to provide reactive power support for the AC system; U is the voltage of the energy storage system; I c is the output current of the energy storage power station; P ref is the energy storage power reference value; i qref is the reference value of the q-axis component on the AC side; I max is the maximum output current of the energy storage system;

[0119] Obtaining the output current of the energy storage power station through the voltage drop area Substitute them into the equations of different fault types to solve them, obtain the accurate sum of short-circuit currents provided by synchronous generators and energy storage power stations, and set the grid short-circuit current constraint as:

[0120] I D,j ≤I D,max (14)

[0121] Among them, I D,j is the short-circuit current of grid node j; I D,max It is the preset maximum allowable value of short-circuit current;

[0122] After the energy storage is connected to the grid, it needs to meet the voltage offset constraint range of the grid. The voltage offset constraint is set as:

[0123]

[0124] Among them, U N is the nominal voltage; U j is the voltage amplitude of grid node j; and They are the lower and upper limits of voltage deviation specified in the technical guidelines respectively;

[0125] Based on the voltage offset constraint range, the short-circuit current and voltage offset of each energy storage configuration scheme are calculated, and the configuration schemes that do not meet the short-circuit current and voltage offset constraints are removed to generate an energy storage configuration scheme that meets the grid safety constraints. 1 ,Φ 2 ,...,Φ p ]; where p is the number of configuration schemes that meet the grid security constraints.

[0126] Preferably, the determining of the energy storage configuration scheme that meets the economic requirements based on the economic requirements objective function includes:

[0127] The economic requirement objective function is:

[0128] minC i =min(X i,1 *c 1 +X i,2 *c 2 +...+X i,k *c k ),n i,k =0 or 1 (16)

[0129] Among them, c 1 、c 2 …c k The total cost of configuring energy storage for the 1st, 2nd…kth new energy stations; X i，1 , X i，2 …X i，k The configuration capacity of the 1st, 2nd…kth new energy fields is S k The amount of energy stored, c k To configure the capacity to S k the cost of energy storage;

[0130] Based on another aspect of the present invention, the present invention provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, and the computer program is used to execute a method for optimizing energy storage configuration to improve the short-circuit ratio of multiple new energy stations.

[0131] Based on another aspect of the present invention, the present invention provides an electronic device, characterized in that the electronic device comprises: a processor and a memory; wherein,

[0132] The memory is a memory for storing instructions executable by the processor;

[0133] The processor is used to read the executable instructions from the memory and execute the instructions to implement a method for optimizing energy storage configuration for improving the short-circuit ratio of multiple renewable energy stations.

[0134] The technical solution of the present invention provides a method and system for optimizing energy storage configuration to improve the short-circuit ratio of multiple renewable energy stations, wherein the method includes: establishing a power grid simulation digital model including multiple renewable energy stations, and determining the selected range of renewable energy stations; calculating the short-circuit ratio of each renewable energy station within the selected range; determining the capacity configuration and access location scheme of the energy storage that each renewable energy station can access; based on the short-circuit ratio of each renewable energy station and the capacity configuration and access location scheme of the energy storage, determining the energy storage configuration scheme of each renewable energy station that meets the short-circuit ratio requirements; based on the safety constraints of the power grid, determining the energy storage configuration scheme that meets the safety constraints of the power grid; based on the economic requirements objective function, determining the energy storage configuration scheme that meets the economic requirements. The technical solution provided by the present invention takes into account multiple safety constraints of the power grid, and realizes the comprehensiveness, safety and economy of the energy storage configuration scheme. BRIEF DESCRIPTION OF THE DRAWINGS

[0135] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0136] Figure 1 A flow chart of an energy storage optimization configuration method for improving the short-circuit ratio of multiple renewable energy stations according to a preferred embodiment of the present invention;

[0137] Figure 2 A flow chart of an energy storage optimization configuration method for improving the short-circuit ratio of multiple renewable energy stations according to a preferred embodiment of the present invention;

[0138] Figure 3 A flow chart of an energy storage configuration scheme that meets the short-circuit ratio requirement according to a preferred embodiment of the present invention;

[0139] Figure 4 A flow chart of an energy storage configuration scheme that meets grid security constraints according to a preferred embodiment of the present invention;

[0140] Figure 5 A flow chart of an energy storage configuration scheme that meets economic requirements according to a preferred embodiment of the present invention; and

[0141] Figure 6 This is a structural diagram of an energy storage optimization configuration system for improving the short-circuit ratio of multiple renewable energy stations according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0142] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0143] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0144] Figure 1 The present invention is a flow chart of a method for optimizing energy storage configuration for improving the short-circuit ratio of multiple renewable energy stations according to a preferred embodiment of the present invention.

[0145] like Figure 1 As shown, the present invention provides a method for optimizing energy storage configuration for improving the short-circuit ratio of multiple renewable energy stations, the method comprising:

[0146] Step 101: Establish a power grid simulation digital model including multiple new energy stations and determine the selection range of the new energy stations;

[0147] Preferably, a power grid simulation digital model including a plurality of new energy stations is established, including a power grid component model, equipment operation limit parameters and new energy station model parameters, wherein:

[0148] The grid component model includes transmission line parameters, transformer parameters, generator node parameters, load node parameters, and generator and spare capacity data; transmission line parameters include resistance, reactance, conductance, and susceptance; transformer parameters include leakage reactance, ratio, and tap position; generator node parameters include active and reactive output values; load node parameters include active and reactive values;

[0149] Equipment operating limit parameters include: line rated current, transformer rated capacity, generator maximum output; generator maximum output includes: active maximum output and reactive maximum output;

[0150] The parameters of the new energy station model include: bus node information, line information and transformer information; bus node information includes: node name, node type, reference voltage, node zone, maximum active output of new energy units, actual active output of new energy units; line information includes: line name, line rated current, resistance per unit value, reactance per unit value, and ground admittance, covering the connecting lines between each new energy unit and the collection station; transformer information includes: transformer name, rated capacity, leakage reactance, transformer tap position, covering the box transformer and step-up transformer of each new energy unit.

[0151] The present invention, in step 101: constructs a power grid simulation digital model including a plurality of new energy stations;

[0152] In step 101, a power grid simulation digital model including a plurality of new energy stations is constructed, including power grid component models, equipment operation limit parameters and new energy station model parameters.

[0153] The grid component model includes transmission line parameters (resistance, reactance, conductance, susceptance), transformer parameters (leakage reactance, ratio, tap position), generator node parameters (active and reactive output values), load node parameters (active and reactive values); generator and reserve capacity data;

[0154] The equipment operating limit parameters include: line rated current, transformer rated capacity, and generator maximum output (maximum active output and maximum reactive output).

[0155] The new energy station model includes bus node information, line information and transformer information. The bus node information includes node name, node type, reference voltage, node zone, maximum active output of new energy units, and actual active output of new energy units; line information includes line name, line rated current, resistance per unit value, reactance per unit value, and ground susceptance, covering the connection lines between each new energy unit and the collection station; transformer information includes transformer name, rated capacity, leakage reactance, and transformer tap position, covering each new energy unit box transformer and step-up transformer.

[0156] Based on the constructed power grid simulation digital model, the scope of new energy sites to be studied is selected.

[0157] Step 102: Calculate the short circuit ratio of each new energy station within the selected range;

[0158] Preferably, calculating the short circuit ratio of each new energy station within the selected range includes:

[0159] The equivalent impedance matrix expression of the AC power grid of the new energy grid-connected bus is:

[0160]

[0161] in, The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The m-th row and m-th column element of ;

[0162] The calculation formula for the short-circuit ratio of multiple renewable energy stations taking into account the mutual influence between multiple renewable energy stations is:

[0163]

[0164] in: is the nominal voltage of the mth grid-connected bus node; The short-circuit current provided for the mth new energy station; The short-circuit current provided for the nth new energy station; is the actual operating voltage of the mth grid-connected bus node; The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The element in the mth row and nth column of ; The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The mth row and mth column element of ; h is the number of grid-connected busbars.

[0165] In step 102 of the present invention: based on the range selected in step 101, the short circuit ratio of each new energy station within the range is calculated;

[0166] In step 102, based on the range selected in step 101, the short-circuit ratio of each new energy station within the range is calculated.

[0167] The AC grid equivalent impedance matrix expression of the new energy grid-connected bus is as follows:

[0168]

[0169] The formula for calculating the short-circuit ratio of multiple renewable energy stations taking into account the mutual influence between multiple renewable energy stations is as follows:

[0170]

[0171] in: is the nominal voltage of the mth grid-connected bus node; The short-circuit current provided for the mth new energy station; The short-circuit current provided for the nth new energy station; is the actual operating voltage of the mth grid-connected bus node; The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The element in the mth row and nth column of ; The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The m-th row and m-th column element of .

[0172] According to the above theoretical formula, the short-circuit ratio of each new energy station within the scope of the study is calculated. The short-circuit ratios are arranged in order from small to large, and compared with the preset minimum short-circuit ratio M. MRSCR(min) Make comparisons and determine the sites that need to be equipped with energy storage.

[0173] Step 103: Determine the capacity configuration and access location plan of the energy storage that can be accessed by each new energy station;

[0174] Preferably, the capacity configuration and access location plan of the energy storage that each new energy station can access is determined, including:

[0175] Assume that the i-th new energy station needs to be connected to energy storage, denoted as Xi ,X i =0 or 1, 0 means no energy storage is connected, 1 means energy storage is connected, and the energy storage that each new energy station needs to connect to is X = [X 1 ,X 2 ,...,X n ];

[0176] Assume that the accessible capacity of energy storage is S = [S 1 ,S 2 ,...,S k ], where S 1 , S 2 , ..., S k The capacity of the access storage;

[0177] Then the energy storage capacity configuration plan of the i-th new energy station is:

[0178] D i =X i,1 *S 1 +X i,2 *S 2 +...+X i,k *S k , X i,k =0 or 1 (3)

[0179] Among them, D i The total capacity of energy storage configured for the i-th new energy station; X i,k Is the i-th new energy station configured with a capacity of S k Energy storage, X i,k The value is 0 or 1.

[0180] The present invention, in step 103: determines the capacity configuration and access location plan of energy storage that can be accessed by each new energy station;

[0181] In step 103, according to actual conditions, the energy storage capacity configuration and access location plan that can be connected to each new energy station are determined:

[0182] First, determine the new energy stations that can be connected to energy storage and the capacity of energy storage that can be connected to each station.

[0183] Assume that the i-th new energy station needs to be connected to energy storage, denoted as X i ,X i It is 0 or 1. 0 means no energy storage is connected, and 1 means energy storage is connected. The energy storage that each station needs to connect to is X = [X 1 ,X 2 ,...,X n ].

[0184] Assume that the accessible storage capacity is S = [S 1 ,S2 ,...,S k ], then the energy storage capacity configuration scheme of the i-th new energy station is

[0185] D i =X i,1 *S 1 +X i,2 *S 2 +...+X i,k *S k , X i,k =0 or 1 (3)

[0186] Among them, D i The total capacity of energy storage configured for the i-th new energy station; X i,k Is the i-th new energy station configured with a capacity of S k Energy storage, X i,k The value is 0 or 1.

[0187] Step 104: Based on the short-circuit ratio of each new energy station, the capacity configuration of the energy storage, and the access location plan, determine the energy storage configuration plan of each new energy station that meets the short-circuit ratio requirement;

[0188] Preferably, based on the short-circuit ratio of each new energy station, the capacity configuration of the energy storage and the access location plan, the energy storage configuration plan of each new energy station that meets the short-circuit ratio requirement is determined, including:

[0189] S1: When there are multiple new energy stations with short circuit ratio Less than the minimum short-circuit ratio M MRSCR(min) When the short circuit ratio is selected The smallest new energy station is connected to energy storage;

[0190] S2: Determine whether the different capacity energy storage configuration schemes generated for the connected new energy stations meet the short-circuit ratio Greater than the minimum short-circuit ratio M MRSCR(min) Configuration scheme;

[0191] S3: When there is a short circuit ratio Greater than the minimum short-circuit ratio M MRSCR(min) If there is no configuration scheme that satisfies the short-circuit ratio, the configuration scheme is retained; Greater than the minimum short-circuit ratio M MRSCR(min) When the configuration scheme is selected, the short circuit ratio Improve the configuration scheme with the largest size;

[0192] S4: Recalculate the short-circuit ratio of the new energy stations and repeat S1-S4 until the short-circuit ratio of all new energy stations is Both are greater than M MRSCR(min) until.

[0193] In step 104 of the present invention: based on step 102 and step 103, an energy storage configuration scheme that meets the short-circuit ratio requirement is determined;

[0194] In step 104, based on step 102 and step 103, an energy storage configuration scheme that meets the short-circuit ratio requirement is determined. Figure 3 .

[0195] First, when the short circuit ratio of multiple renewable energy stations is Less than the minimum short-circuit ratio M MRSCR(min) When The smallest station is connected to the energy storage. The different capacity energy storage configuration schemes generated for the station in step 103 are connected in sequence, and the one that meets the requirements is selected. Greater than M MRSCR(min) If no configuration is met Greater than M MRSCR(min) If you want to use the configuration scheme, select Improve the configuration plan the most.

[0196] Then, recalculate the short-circuit ratio of each new energy station within the scope of the study, and arrange the short-circuit ratios in order from small to large. Select the current new energy multi-station with the smallest short-circuit ratio and lower than M MRSCR(min) The new energy station continues to connect to the energy storage. Sequentially connect to the different capacity energy storage configuration solutions generated for the station in step 103, and select the one that meets M MRSCRi Greater than M MRSCR(min) If there is no configuration scheme that satisfies M MRSCRi Greater than M MRSCR(min) If the configuration scheme is M MRSCRi Improve the configuration plan the most.

[0197] Finally, the above steps are repeated until the short-circuit ratio of all new energy stations is greater than M. MRSCR(min) At this point, several energy storage configuration schemes are available Ω=[Ω 1 ,Ω 2 ,...,Ω m ]. Where m is the number of configuration schemes that meet the short-circuit ratio requirements.

[0198] Step 105: Based on the grid security constraints, determine an energy storage configuration solution that meets the grid security constraints;

[0199] Preferably, based on the grid security constraints, an energy storage configuration scheme satisfying the grid security constraints is determined, wherein the grid security constraints include: short-circuit current and voltage offset constraints;

[0200] Evaluate the short-circuit current of the energy storage system after adding energy storage, and determine whether the short-circuit current exceeds the short-circuit current threshold: the energy storage is equivalent to a controlled current source. When the voltage continues to drop after a short circuit, the low-voltage control allows the energy storage system to continue to operate without disconnecting from the grid, and the reactive support is increased by energy storage to restore the voltage at the grid connection point; when the grid fails, the energy storage system is equivalent to a current source, which is used as an equivalent model of the energy storage system in the short-circuit current calculation. The output current of the energy storage system is:

[0201] I c =K bat K.I N (4)

[0202] Among them, K is the allowable overcurrent multiple, ranging from 1.2 to 1.5; K bat is the output current coefficient of different batteries, I N is the rated output current of the energy storage system;

[0203] When a three-phase short circuit fault occurs at a certain point in the energy storage system, for a normal network, it is equivalent to adding an injection current at the fault point k. The voltage at any point i in the network is expressed as:

[0204]

[0205] Among them, G is the set of active nodes in the network; Z ij is the mutual impedance between the ij nodes; is the injected current of node j; Z ik is the impedance of the fault point k; j is the node; the voltage at any node includes two voltage superpositions, the first is the normal component of the node voltage before the short circuit, and the second is when the three-phase voltage source in the network is short-circuited, the equivalent current source is open-circuited, which is the short-circuit current The voltage generated at node k is also the fault component of the node voltage. The voltage at the fault point is obtained by superimposing the two voltages. For the fault point, the circuit current at the fault point is obtained by combining the boundary conditions of the fault point:

[0206]

[0207] in, is the fault point voltage; Z f is the grounding resistance at the fault point; is the normal component of the node voltage before short circuit; Z kk is the k-node self-impedance; decompose the three-phase quantity generated by the asymmetric fault into positive, negative and zero sequence, establish the three-sequence network equation, and then establish the boundary conditions according to the superposition principle to solve the short-circuit current of each sequence network, where the network equation of each sequence network is:

[0208]

[0209]

[0210] in, are the positive sequence voltage, negative sequence voltage and zero sequence voltage of the fault port respectively; is the external voltage source voltage; are the sequence components of the fault current injected by the power supply to the fault point respectively; are the equivalent impedance matrices of each sequence network respectively; to are the positive sequence network impedance respectively; to are the negative sequence network impedance respectively; to are zero-sequence network impedance respectively; m is the fault node; n is the number of nodes;

[0211] Set the boundary conditions for single-phase ground fault:

[0212]

[0213] Set the boundary conditions for a two-phase short-circuit fault:

[0214]

[0215] Boundary conditions of two-phase ground short circuit fault:

[0216]

[0217] The short-circuit current obtained from the symmetrical fault and asymmetrical fault of the network equation is combined with the constraints of the converter type power supply to obtain the energy storage system equation:

[0218]

[0219] in, It is the additional phase angle generated by the energy storage system to provide reactive power support for the AC system; U is the voltage of the energy storage system; I c is the output current of the energy storage power station; P ref is the energy storage power reference value; i qref is the reference value of the q-axis component on the AC side; I max is the maximum output current of the energy storage system;

[0220] Obtaining the output current of the energy storage power station through the voltage drop area Substitute them into the equations of different fault types to solve them, obtain the accurate sum of short-circuit currents provided by synchronous generators and energy storage power stations, and set the grid short-circuit current constraint as:

[0221] I D,j ≤ID,max (14)

[0222] Among them, I D,j is the short-circuit current of grid node j; I D,max It is the preset maximum allowable value of short-circuit current;

[0223] After the energy storage is connected to the grid, it needs to meet the voltage offset constraint range of the grid. The voltage offset constraint is set as:

[0224]

[0225] Among them, U N is the nominal voltage; U j is the voltage amplitude of grid node j; and They are the lower and upper limits of voltage deviation specified in the technical guidelines respectively;

[0226] Based on the voltage offset constraint range, the short-circuit current and voltage offset of each energy storage configuration scheme are calculated, and the configuration schemes that do not meet the short-circuit current and voltage offset constraints are removed to generate an energy storage configuration scheme that meets the grid safety constraints. 1 ,Φ 2 ,...,Φ p ]; where p is the number of configuration schemes that meet the grid security constraints.

[0227] In step 105 of the present invention: based on the solution of step 104, short-circuit current and voltage offset constraints are considered to determine an energy storage configuration solution that meets the grid safety constraints;

[0228] In step 105, based on the solution of step 104, short-circuit current and voltage offset constraints are considered to determine an energy storage configuration solution that meets the grid safety constraints.

[0229] Energy storage will inject short-circuit current into the system when a fault occurs. Therefore, it is necessary to evaluate the system short-circuit current level after adding energy storage to determine whether it will cause the short-circuit current to exceed the standard.

[0230] The energy storage is equivalent to a controlled current source. When the voltage continues to drop after a short circuit, the low-break control allows the energy storage system to operate continuously without disconnecting from the grid, and the energy storage increases the reactive power to support the voltage recovery at the grid connection point. The higher the voltage drop, the greater the short-circuit current output by the energy storage power station. When the power grid fails, the energy storage system is equivalent to a current source, which is used as the equivalent model of the energy storage system in the short-circuit current calculation. The output current of the energy storage system is:

[0231] I c =K bat K.I N (4)

[0232] Where: K is the allowable overcurrent multiple, and the value range is usually around 1.2 to 1.5. bat is the output current coefficient of different batteries, I N is the rated output current of the energy storage system.

[0233] (1) Three-phase symmetrical short-circuit calculation

[0234] When a three-phase short circuit fault occurs at a certain point in the system, for a normal network, it is equivalent to adding an injection current at the fault point k. The voltage at any point i in the network can be expressed as:

[0235]

[0236] G is the set of active nodes in the network.

[0237] From the superposition theorem, we know that any node voltage is composed of two terms. The first term is the normal component of the node voltage before the short circuit, and the second term is when the three-phase voltage source in the network is short-circuited, the equivalent current source is open-circuited, and only the short-circuit current The voltage generated at node k is also the fault component of the node voltage. The two components are superimposed to obtain the fault point voltage. For the fault point, the fault point circuit current is obtained by combining the boundary conditions of the fault point:

[0238]

[0239] (2) Three-phase asymmetric short circuit calculation

[0240] The three-phase quantities generated by the asymmetric fault are decomposed into positive, negative and zero sequences, and the three-sequence network equation is established. Then, according to the superposition principle, the boundary conditions are established to solve the short-circuit current of each sequence network.

[0241] Each sequence network equation:

[0242]

[0243] Boundary conditions:

[0244] Boundary conditions for single-phase ground fault:

[0245]

[0246] Boundary conditions for two-phase short-circuit fault:

[0247]

[0248] Boundary conditions of two-phase ground short circuit fault:

[0249]

[0250] By combining the short-circuit current obtained from the symmetrical fault and asymmetrical fault of the network equation with the constraints of the converter type power supply, the following system equation can be obtained:

[0251]

[0252] Obtaining the output current of the energy storage power station through the voltage drop area By substituting the different fault types into the equations and solving them, we can get the accurate sum of short-circuit currents provided by the synchronous generator and the energy storage power station.

[0253] Therefore, the grid short-circuit current constraint is set to

[0254] I D,j ≤I D,max (14)

[0255] Among them, I D,j is the short-circuit current of grid node j; I D,max The maximum allowable short-circuit current specified in the technical guidelines.

[0256] On the other hand, after the energy storage is connected to the grid, it must meet the voltage offset constraint range of the grid. Therefore, the voltage offset constraint is set as

[0257]

[0258] Among them, U N is the nominal voltage; U j is the voltage amplitude of grid node j; and They are the lower and upper limits of voltage deviation specified in the technical guidelines respectively.

[0259] Based on the above constraints, the short-circuit current and voltage offset of each energy storage configuration scheme in step 4 are calculated. The configuration schemes that do not meet the short-circuit current and voltage offset constraints are eliminated to generate an energy storage configuration scheme that meets the grid safety constraints. 1 ,Φ 2 ,...,Φ p ]. Where p is the number of configuration schemes that meet the grid security constraints.

[0260] Step 106: Based on the economic requirement objective function, determine an energy storage configuration solution that meets the economic requirements.

[0261] Preferably, based on the economic requirement objective function, determining an energy storage configuration scheme that meets the economic requirements includes:

[0262] The economic requirement objective function is:

[0263] minC i =min(X i,1*c 1 +X i,2 *c 2 +...+X i,k *c k ) (16)

[0264] Among them, c 1 、c 2 …c k The total cost of configuring energy storage for the 1st, 2nd…kth new energy stations; X i，1 , X i，2 …X i，k The configuration capacity of the 1st, 2nd…kth new energy stations is S k The amount of energy storage, c k To configure the capacity to S k the cost of energy storage;

[0265] The present invention, at step 106 , determines an energy storage configuration scheme that meets the economic requirements based on the objective function.

[0266] In step 106, based on the objective function, an energy storage configuration scheme that meets the economic requirements is determined.

[0267] The purpose of configuring energy storage is to ensure optimal economic performance while improving the short-circuit ratio of multiple renewable energy stations. Therefore, the energy storage configuration objectives are:

[0268] minC i =min(X i,1 *c 1 +X i,2 *c 2 +...+X i,k *c k ),n i,k =0 or 1 (16)

[0269] Among them, C i The total cost of configuring energy storage for the i-th new energy station; X i,k Whether the i-th new energy station is equipped with energy storage and the configured capacity is S k , c k To configure the capacity to S k The unit price of energy storage.

[0270] Based on the above objective function, the most economical solution among the energy storage configuration solutions that meet the grid security constraints is selected, which is the final configuration result.

[0271] Figure 6 This is a structural diagram of an energy storage optimization configuration system for improving the short-circuit ratio of multiple renewable energy stations according to a preferred embodiment of the present invention.

[0272] like Figure 6As shown, the present invention provides an energy storage optimization configuration system for improving the short-circuit ratio of multiple new energy stations, and the system includes:

[0273] A power grid simulation digital model building unit 601 is used to build a power grid simulation digital model including multiple new energy stations and determine the selection range of the new energy stations;

[0274] A new energy multi-station short circuit ratio calculation unit 602 is used to calculate the short circuit ratio of each new energy station within a selected range;

[0275] The energy storage capacity configuration unit 603 is used to determine the capacity configuration and access location plan of the energy storage that each new energy station can access;

[0276] The short circuit ratio constraint unit 604 is used to determine the energy storage configuration scheme of each new energy station that meets the short circuit ratio requirement based on the short circuit ratio of each new energy station, the capacity configuration of the energy storage and the access location scheme;

[0277] A power grid security constraint unit 605, configured to determine an energy storage configuration scheme that satisfies the power grid security constraint based on the power grid security constraint;

[0278] The economic constraint unit 606 is used to determine the energy storage configuration scheme that meets the economic requirements based on the economic requirements objective function. Preferably, a power grid simulation digital model including multiple new energy stations is established, including a power grid component model, equipment operation limit parameters and new energy station model parameters, wherein:

[0279] The grid component model includes transmission line parameters, transformer parameters, generator node parameters, load node parameters, and generator and spare capacity data; transmission line parameters include resistance, reactance, conductance, and susceptance; transformer parameters include leakage reactance, ratio, and tap position; generator node parameters include active and reactive output values; load node parameters include active and reactive values;

[0280] Equipment operating limit parameters include: line rated current, transformer rated capacity, generator maximum output; generator maximum output includes: active maximum output and reactive maximum output;

[0281] The parameters of the new energy station model include: bus node information, line information and transformer information; bus node information includes: node name, node type, reference voltage, node zone, maximum active output of new energy units, actual active output of new energy units; line information includes: line name, line rated current, resistance per unit value, reactance per unit value, and ground admittance, covering the connecting lines between each new energy unit and the collection station; transformer information includes: transformer name, rated capacity, leakage reactance, transformer tap position, covering the box transformer and step-up transformer of each new energy unit.

[0282] Preferably, calculating the short circuit ratio of each new energy station within the selected range includes:

[0283] The equivalent impedance matrix expression of the AC power grid of the new energy grid-connected bus is:

[0284]

[0285] in, The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The m-th row and m-th column element of ;

[0286] The calculation formula for the short-circuit ratio of multiple renewable energy stations taking into account the mutual influence between multiple renewable energy stations is:

[0287]

[0288] in: is the nominal voltage of the mth grid-connected bus node; The short-circuit current provided for the mth new energy station; The short-circuit current provided for the nth new energy station; is the actual operating voltage of the mth grid-connected bus node; The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The element in the mth row and nth column of ; The AC power grid equivalent impedance matrix of the busbar at the new energy grid connection point is The mth row and mth column element of ; h is the number of grid-connected busbars.

[0289] Preferably, the capacity configuration and access location plan of the energy storage that each new energy station can access is determined, including:

[0290] Assume that the i-th new energy station needs to be connected to energy storage, denoted as X i ,X i =0 or 1, 0 means no energy storage is connected, 1 means energy storage is connected, and the energy storage that each new energy station needs to connect to is X = [X 1 ,X 2 ,...,X n ];

[0291] Assume that the accessible capacity of energy storage is S = [S 1 ,S 2 ,...,S k ], where S 1 , S 2 , ..., S k The capacity of the access storage;

[0292] Then the energy storage capacity configuration plan of the i-th new energy station is:

[0293] D i =X i,1 *S 1 +X i,2 *S 2 +...+X i,k *S k , X i,k =0 or 1 (3)

[0294] Among them, D i The total capacity of energy storage configured for the i-th new energy station; X i,k Is the i-th new energy station configured with a capacity of S k Energy storage, X i,k The value is 0 or 1.

[0295] Preferably, based on the short-circuit ratio of each new energy station and the capacity configuration and access location plan of the energy storage, the energy storage configuration plan of each new energy station that meets the short-circuit ratio requirement is determined, including:

[0296] S1: When there are multiple new energy stations with short circuit ratio Less than the minimum short-circuit ratio M MRSCR(min) When the short circuit ratio is selected The smallest new energy station is connected to energy storage;

[0297] S2: Determine whether the different capacity energy storage configuration schemes generated for the connected new energy stations meet the short-circuit ratio Greater than the minimum short-circuit ratio M MRSCR(min) Configuration scheme;

[0298] S3: When there is a short circuit ratio Greater than the minimum short-circuit ratio M MRSCR(min) If there is no configuration scheme that satisfies the short-circuit ratio, the configuration scheme is retained; Greater than the minimum short-circuit ratio M MRSCR(min) When the configuration scheme is selected, the short circuit ratio Improve the configuration scheme with the largest size;

[0299] S4: Recalculate the short-circuit ratio of the new energy stations and repeat S1-S4 until the short-circuit ratio of all new energy stations is Both are greater than M MRSCR(min) until.

[0300] Preferably, based on the grid security constraints, an energy storage configuration scheme satisfying the grid security constraints is determined, wherein the grid security constraints include: short-circuit current and voltage offset constraints;

[0301] Evaluate the short-circuit current of the energy storage system after adding energy storage, and determine whether the short-circuit current exceeds the short-circuit current threshold: the energy storage is equivalent to a controlled current source. When the voltage continues to drop after a short circuit, the low-voltage control allows the energy storage system to continue to operate without disconnecting from the grid, and the reactive support is increased by energy storage to restore the voltage at the grid connection point; when the grid fails, the energy storage system is equivalent to a current source, which is used as an equivalent model of the energy storage system in the short-circuit current calculation. The output current of the energy storage system is:

[0302] I c =K bat K.I N (4)

[0303] Among them, K is the allowable overcurrent multiple, ranging from 1.2 to 1.5; K bat is the output current coefficient of different batteries, I N is the rated output current of the energy storage system;

[0304] When a three-phase short circuit fault occurs at a certain point in the energy storage system, for a normal network, it is equivalent to adding an injection current at the fault point k. The voltage at any point i in the network is expressed as:

[0305]

[0306] Among them, G is the set of active nodes in the network; Z ij is the mutual impedance between the ij nodes; is the injected current of node j; Z ik is the impedance of fault point k; j is node j;

[0307] Any node voltage consists of two voltage superpositions. The first is the normal component of the node voltage before the short circuit. The second is when the three-phase voltage source in the network is short-circuited and the equivalent current source is open-circuited. The voltage generated at node k is also the fault component of the node voltage. The voltage at the fault point is obtained by superimposing the two voltages. For the fault point, the circuit current at the fault point is obtained by combining the boundary conditions of the fault point:

[0308]

[0309] in, is the fault point voltage; Z f is the grounding resistance at the fault point; is the normal component of the node voltage before short circuit; Z kk is the k-node self-impedance; decompose the three-phase quantity generated by the asymmetric fault into positive, negative and zero sequence, establish the three-sequence network equation, and then establish the boundary conditions according to the superposition principle to solve the short-circuit current of each sequence network, where the network equation of each sequence network is:

[0310]

[0311] in, are the positive sequence voltage, negative sequence voltage and zero sequence voltage of the fault port respectively; is the external voltage source voltage; are the sequence components of the fault current injected by the power supply to the fault point respectively; are the equivalent impedance matrices of each sequence network respectively; to are the positive sequence network impedance respectively; to are the negative sequence network impedance respectively; to are zero-sequence network impedance respectively; m is the fault node; n is the number of nodes;

[0312] Set the boundary conditions for single-phase ground fault:

[0313]

[0314] Set the boundary conditions for a two-phase short-circuit fault:

[0315]

[0316] Boundary conditions of two-phase ground short circuit fault:

[0317]

[0318] The short-circuit current obtained from the symmetrical fault and asymmetrical fault of the network equation is combined with the constraints of the converter type power supply to obtain the energy storage system equation:

[0319]

[0320] in, It is the additional phase angle generated by the energy storage system to provide reactive power support for the AC system; U is the voltage of the energy storage system; I c is the output current of the energy storage power station; P ref is the energy storage power reference value; i qref is the reference value of the q-axis component on the AC side; I max is the maximum output current of the energy storage system;

[0321] Obtaining the output current of the energy storage power station through the voltage drop area Substitute them into the equations of different fault types to solve them, obtain the accurate sum of short-circuit currents provided by synchronous generators and energy storage power stations, and set the grid short-circuit current constraint as:

[0322] I D,j ≤I D,max (14)

[0323] Among them, I D,j is the short-circuit current of grid node j; I D,max It is the preset maximum allowable value of short-circuit current;

[0324] After the energy storage is connected to the grid, it needs to meet the voltage offset constraint range of the grid. The voltage offset constraint is set as:

[0325]

[0326] Among them, U N is the nominal voltage; U j is the voltage amplitude of grid node j; and They are the lower and upper limits of voltage deviation specified in the technical guidelines respectively;

[0327] Based on the voltage offset constraint range, the short-circuit current and voltage offset of each energy storage configuration scheme are calculated, and the configuration schemes that do not meet the short-circuit current and voltage offset constraints are removed to generate an energy storage configuration scheme that meets the grid safety constraints. 1 ,Φ 2 ,...,Φ p ]; where p is the number of configuration schemes that meet the grid security constraints.

[0328] Preferably, based on the economic requirement objective function, determining an energy storage configuration scheme that meets the economic requirements includes:

[0329] The economic requirement objective function is:

[0330] minC i =min(X i,1 *c 1 +X i,2 *c 2 +...+X i,k *c k ) (16)

[0331] Among them, c 1 、c 2 …c k The total cost of configuring energy storage for the 1st, 2nd…kth new energy stations; X i，1 , X i，2 …X i，k The configuration capacity of the 1st, 2nd…kth new energy stations is S k Energy storage, c k To configure the capacity to S k The cost of energy storage.

[0332] The present invention provides a computer-readable storage medium, which stores a computer program. The computer program is used to execute a method for optimizing energy storage configuration for improving the short-circuit ratio of multiple renewable energy stations.

[0333] The present invention provides an electronic device, the electronic device comprising: a processor and a memory; wherein:

[0334] Memory, a memory for storing processor executable instructions;

[0335] The processor is used to read executable instructions from a memory and execute the instructions to implement an energy storage optimization configuration method for improving the short-circuit ratio of multiple renewable energy stations.

[0336] The present application also provides an energy storage optimization configuration system for improving the short-circuit ratio of multiple renewable energy stations, including:

[0337] A power grid simulation digital model building unit is used to obtain power grid component models, equipment operating limit parameters, and new energy station model parameters;

[0338] A new energy multi-station short-circuit ratio calculation unit is used to calculate the short-circuit ratio of each new energy station within the scope to be studied;

[0339] Energy storage capacity configuration unit, which determines the energy storage capacity configuration and access location plan that can be connected to each new energy station;

[0340] A short-circuit ratio constraint unit, used to determine an energy storage configuration scheme that meets the short-circuit ratio requirements;

[0341] A grid security constraint unit is used to consider short-circuit current and voltage offset constraints and determine the energy storage configuration scheme that meets the grid security constraints;

[0342] The economic constraint unit is used to determine the energy storage configuration scheme that meets the economic requirements.

[0343] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0344] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0345] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0346] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0347] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0348] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0349] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0350] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / said / the [means, components, etc.]" are to be openly interpreted as at least one instance of the means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

Claims

1. A method for optimizing energy storage configuration to improve the short-circuit ratio of multiple renewable energy stations, the method comprising: Establish a digital model of power grid simulation that includes multiple new energy stations and determine the selection range of new energy stations; Calculate the short-circuit ratio of each new energy station within the selected range; Determine the capacity configuration and access location plan of energy storage that can be connected to each new energy station; Based on the short-circuit ratio of each new energy station, the capacity configuration of energy storage and the access location plan, determine the energy storage configuration plan for each new energy station that meets the short-circuit ratio requirements; Based on grid security constraints, determine the energy storage configuration scheme that meets grid security constraints; Based on the economic requirement objective function, determine the energy storage configuration plan that meets the economic requirements.

2. According to the method of claim 1, the establishment of a power grid simulation digital model including a plurality of new energy stations includes a power grid component model, equipment operating limit parameters and new energy station model parameters, wherein: The grid element model includes transmission line parameters, transformer parameters, generator node parameters, load node parameters, and generator and spare capacity data; The transmission line parameters include resistance, reactance, conductance, and susceptance; the transformer parameters include leakage reactance, transformation ratio, and tap position; the generator node parameters include active and reactive output values; the load node parameters include active and reactive values; The equipment operation limit parameters include: line rated current, transformer rated capacity, and generator maximum output; the generator maximum output includes: active maximum output and reactive maximum output; The new energy station model parameters include: bus node information, line information and transformer information; the bus node information includes: node name, node type, reference voltage, node zone, maximum active output of new energy units, and actual active output of new energy units; the line information includes: line name, line rated current, per unit resistance value, per unit reactance value, and earth susceptance, covering the connecting lines between each new energy unit and the collection station; the transformer information includes: transformer name, rated capacity, leakage reactance, and transformer tap position, covering the box transformer and step-up transformer of each new energy unit.

3. According to the method of claim 1, the step of calculating the short circuit ratio of each new energy station within the selected range comprises: The equivalent impedance matrix expression of the AC power grid of the new energy grid-connected bus is: in, The AC grid equivalent impedance matrix of the busbar at the new energy grid connection point is The m-th row and m-th column element of ; The calculation formula for the short-circuit ratio of multiple renewable energy stations taking into account the mutual influence between multiple renewable energy stations is: in: is the nominal voltage of the mth grid-connected bus node; The short-circuit current provided for the mth new energy station; The short-circuit current provided for the nth new energy station; is the actual operating voltage of the mth grid-connected bus node; The AC grid equivalent impedance matrix of the busbar at the new energy grid connection point is The element in the mth row and nth column of ; The AC grid equivalent impedance matrix of the busbar at the new energy grid connection point is The mth row and mth column element of ; h is the number of grid-connected busbars.

4. According to the method of claim 1, the step of determining the capacity configuration and access location plan of the energy storage that each new energy station can access comprises: Assume that the i-th new energy station needs to be connected to energy storage, denoted as X i ,X i It is 0 or 1, 0 means no access to energy storage, 1 means access to energy storage. The energy storage that each new energy station needs to access is X = [X1, X2, ..., X n ]; Assume that the accessible capacity of energy storage is S = [S1, S2, ..., S k ], where S1, S2, ..., S k Capacity for access to energy storage Then the energy storage capacity configuration plan of the i-th new energy station is: D i = X i,1 * S1 + X i,2 * S2 +... + X i,k * S k ,X i,k = 0 or 1 (3) Among them, D i The total capacity of energy storage configured for the i-th new energy station; X i,k Is the i-th new energy station configured with a capacity of S k Energy storage, X i,k The value is 0 or 1.

5. The method according to claim 1, wherein the energy storage configuration scheme of each new energy station that meets the short circuit ratio requirement is determined based on the short circuit ratio of each new energy station and the capacity configuration and access location scheme of the energy storage, comprising: S1: When there are multiple new energy stations with short circuit ratio Less than the minimum short-circuit ratio M MRSCR(min) When the short circuit ratio is selected The smallest new energy station is connected to energy storage; S2: Determine whether the different capacity energy storage configuration schemes generated for the connected new energy stations meet the short-circuit ratio Greater than the minimum short-circuit ratio M MRSCR(min) Configuration scheme; S3: When there is a short circuit ratio Greater than the minimum short-circuit ratio M MRSCR(min) If there is no configuration scheme that satisfies the short-circuit ratio, the configuration scheme is retained; Greater than the minimum short-circuit ratio M MRSCR(min) When the configuration scheme is selected, the short circuit ratio Improve the configuration scheme with the greatest improvement; S4: Recalculate the short-circuit ratio of the new energy stations and repeat S1-S4 until the short-circuit ratio of all new energy stations is Both are greater than M MRSCR(min) until.

6. The method according to claim 1, wherein the energy storage configuration scheme that satisfies the grid security constraints is determined based on the grid security constraints, wherein: The grid safety constraints include: short-circuit current and voltage deviation constraints; Evaluate the short-circuit current of the energy storage system after adding energy storage, and determine whether the short-circuit current exceeds the short-circuit current threshold: the energy storage is equivalent to a controlled current source. When the voltage continues to drop after a short circuit, the low-voltage control enables the energy storage system to continue to operate without disconnecting from the grid, and the reactive support is increased by energy storage to restore the voltage at the grid connection point; when the grid fails, the energy storage system is equivalent to a current source as an equivalent model of the energy storage system in the short-circuit current calculation. The output current of the energy storage system is: I c =K bat K·I N (4) Among them, K is the allowable overcurrent multiple, ranging from 1.2 to 1.5; K bat is the output current coefficient of different batteries, I N is the rated output current of the energy storage system; When a three-phase short circuit fault occurs at a certain point in the energy storage system, for a normal network, it is equivalent to adding an injection current at the fault point k. The voltage at any point i in the network is expressed as: Among them, G is the set of active nodes in the network; Z ij is the mutual impedance between the ij nodes; is the injected current of node j; Z ik is the impedance of fault point k; j is the node; Any node voltage consists of two voltage superpositions. The first is the normal component of the node voltage before the short circuit. The second is when the three-phase voltage source in the network is short-circuited and the equivalent current source is open-circuited. The voltage generated at node k is also the fault component of the node voltage. The voltage at the fault point is obtained by superimposing the two voltages. For the fault point, the circuit current at the fault point is obtained by combining the boundary conditions of the fault point: in, is the fault point voltage; Z f is the grounding resistance at the fault point; is the normal component of the node voltage before short circuit; Z kk is the k-node self-impedance; The three-phase quantity generated by the asymmetric fault is decomposed into positive, negative and zero sequence, and the three-sequence network equation is established. Then, according to the superposition principle, the boundary conditions are established to solve the short-circuit current of each sequence network, where the network equation of each sequence network is: in, are the positive sequence voltage, negative sequence voltage and zero sequence voltage of the fault port respectively; is the external voltage source voltage; are the sequence components of the fault current injected by the power supply to the fault point respectively; are the equivalent impedance matrices of each sequence network respectively; to are the positive sequence network impedance respectively; to are the negative sequence network impedance respectively; to are zero-sequence network impedance respectively; m is the fault node; n is the number of nodes; Set the boundary conditions for single-phase to ground fault: Set the boundary conditions for a two-phase short-circuit fault: Boundary conditions of two-phase ground short circuit fault: The short-circuit current obtained from the symmetrical fault and asymmetrical fault of the network equation is combined with the constraints of the converter type power supply to obtain the energy storage system equation: in, It is the additional phase angle generated by the energy storage system to provide reactive power support for the AC system; U is the voltage of the energy storage system; I c is the output current of the energy storage power station; P ref is the reference value of energy storage power; i qref is the reference value of the q-axis component on the AC side; I max is the maximum output current of the energy storage system; Obtaining the output current of the energy storage power station through the voltage drop area Substitute them into the equations of different fault types to solve them, obtain the accurate sum of short-circuit currents provided by synchronous generators and energy storage power stations, and set the grid short-circuit current constraint as: I D,j ≤I D,max (14) Among them, I D,j is the short-circuit current of grid node j; I D,max It is the preset maximum allowable value of short-circuit current; After the energy storage is connected to the grid, it needs to meet the voltage offset constraint range of the grid. The voltage offset constraint is set as: Among them, U N is the nominal voltage; U j is the voltage amplitude of grid node j; and They are the lower and upper limits of voltage deviation specified in the technical guidelines respectively; Based on the voltage offset constraint range, the short-circuit current and voltage offset of each energy storage configuration scheme are calculated, and the configuration schemes that do not meet the short-circuit current and voltage offset constraints are removed to generate an energy storage configuration scheme that meets the grid safety constraints. p ]; where p is the number of configuration schemes that meet the grid security constraints.

7. The method according to claim 1, wherein determining the energy storage configuration scheme that meets the economic requirements based on the economic requirements objective function comprises: The economic requirement objective function is: minC i =min(X i,1 *c1+X i,2 *c2+...+X i,k *c k ) (16) Among them, c1, c2…c k The total cost of configuring energy storage for the 1st, 2nd…kth new energy stations; X i，1 , X i，2 …X i，k The configuration capacity of the 1st, 2nd…kth new energy fields is S k The amount of energy stored, c k To configure the capacity to S k The cost of energy storage.

8. An energy storage optimization configuration system for improving the short-circuit ratio of multiple renewable energy stations, the system comprising: A power grid simulation digital model building unit is used to build a power grid simulation digital model including multiple new energy stations and determine the selection range of the new energy stations; A new energy multi-station short-circuit ratio calculation unit, used to calculate the short-circuit ratio of each new energy station within a selected range; The energy storage capacity configuration unit is used to determine the capacity configuration and access location plan of the energy storage that each new energy station can access; A short circuit ratio constraint unit is used to determine the energy storage configuration plan of each new energy station that meets the short circuit ratio requirements based on the short circuit ratio of each new energy station, the capacity configuration of the energy storage and the access location plan; A power grid security constraint unit, used to determine an energy storage configuration scheme that satisfies the power grid security constraints based on the power grid security constraints; The economic constraint unit is used to determine the energy storage configuration scheme that meets the economic requirements based on the economic requirement objective function.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 7.

10. An electronic device, characterized in that: The electronic device comprises: a processor and a memory; wherein, The memory is a memory for storing instructions executable by the processor; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method according to any one of claims 1 to 7.

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