Voltage control method of energy storage wind farm based on optimal control

Abstract

The present invention discloses a voltage control method for an energy storage wind farm based on optimal control. The method comprises: constructing a linearized branch power flow model based on the energy storage wind farm topology to obtain the relationship between voltage and power; establishing an energy storage system increment model to obtain the relationship between the energy of the energy storage system and the charge and discharge power; obtaining the energy of the energy storage system and the node voltage of the energy storage wind farm, and using these to construct a first-stage objective function and a second-stage objective function; then establishing constraints based on the power of the wind turbines in the energy storage wind farm and the charge and discharge power of the energy storage units in the energy storage system; solving a mathematical model for wind farm voltage control composed of the above models to obtain the optimal value of the charge and discharge power of the energy storage system; and adjusting the reactive output of the wind turbines and the energy storage system in the energy storage wind farm based on the optimal value of the charge and discharge power of the energy storage system. The present invention can effectively suppress node voltage fluctuations and maintain node voltage stability.

Description

Technical Field

[0001] The present invention relates to the field of power grid voltage control, and in particular to a wind farm voltage control method based on optimal control. Background Art

[0002] Due to the randomness and intermittency of wind energy, the reactive voltage characteristics of wind power differ from those of conventional energy sources such as thermal power and hydropower. When large-scale wind power is integrated into the grid, new reactive voltage problems arise. These reactive voltage issues primarily manifest themselves in two ways. First, current wind turbines are equipped with inherent protection devices, such as undervoltage and overvoltage protection. Once the voltage exceeds the safety range, the turbines themselves will trip, easily causing a large number of turbines in a local area to go offline, resulting in a significant loss of power to the power system in a short period of time, significantly impacting the safe operation of the grid. Second, the inherent randomness and volatility of wind power can cause numerous problems such as voltage fluctuations and harmonics when connected to the grid. Furthermore, excessive wind power output can reduce the voltage safety margin, which can easily lead to voltage collapse.

[0003] An effective reactive voltage control strategy is very necessary for the safe operation and stable grid connection of wind farms. For the above problems, appropriate reactive compensation equipment can be used, such as parallel power capacitors at the unit end, parallel SVC and STATCOM at the entrance of the wind farm, etc., which can provide reactive compensation capacity, which can improve the voltage stability and reactive power output of the wind farm to a certain extent. In addition, the energy storage system has the function of storing and releasing electric energy in a timely manner, can smooth out the fluctuations of new energy output, participate in the frequency and voltage regulation of the power grid, and is widely used in the field of new energy power generation and grid connection. Among them, battery energy storage has the characteristics of fast response speed, flexible power and energy configuration, and installation without geographical restrictions, making it the energy storage technology with the greatest potential for large-scale application. In order to improve the friendliness of wind power and increase its absorption ratio, it has become an effective measure to configure a large-capacity energy storage system for the wind farm and build it into an energy storage wind farm. Configuring a certain proportion of energy storage devices according to the installed capacity has been adopted by more and more wind farms, forming an energy storage wind farm with wind power generation system as the main body and energy storage system as the auxiliary. Figure 1 As shown in Figure 2 , adding energy storage devices to wind farms and utilizing the energy storage system to temporarily store wind energy can increase wind energy utilization. Furthermore, combining wind power generation with energy storage systems can reduce output power fluctuations and address large-scale grid connection issues. Therefore, integrating energy storage systems with wind power generation systems to form energy storage-based wind farms has become a key approach to addressing large-scale wind power grid connection issues. Currently, several energy storage-based wind farm demonstration projects utilizing battery energy storage technology are operational both domestically and internationally. The deployment of battery energy storage systems in wind farms significantly enhances overall controllability, increases operational flexibility, and improves operational performance.

[0004] In recent years, OPC (Optimal Control) has been widely used to optimize the coordinated control of active and reactive power in wind farms. OPC can coordinate wind turbines and energy storage under different operating conditions, simplifying the nonlinear wind farm model into a linearized one for rapid solution.

[0005] In summary, in the context of the continuous increase in wind power grid-connected capacity and power generation, research on OPC-based energy storage wind farm grid voltage control technology is of great significance for improving the safe and stable operation level of the power grid. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: In response to the technical problems existing in the prior art, the present invention provides a wind farm voltage control method based on optimal control, which optimizes the charging and discharging power of energy storage, provides rapid reactive power support for the dynamic reactive capacity of the energy storage system, suppresses node voltage fluctuations, and maintains node voltage stability.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0008] A voltage control method for an energy storage type wind farm based on optimal control comprises the following steps:

[0009] S1) constructing a linearized branch power flow model in a wind farm voltage control mathematical model based on the topology of the energy storage wind farm, and obtaining the relationship between voltage and power in the energy storage wind farm;

[0010] S2) establishing an incremental model of the energy storage system in the mathematical model of wind farm voltage control, and obtaining the relationship between the energy and charging and discharging power of the energy storage system in the energy storage type wind farm;

[0011] S3) obtaining energy of an energy storage system in the energy storage type wind farm and node voltages of the energy storage type wind farm, and constructing a first-stage objective function and a second-stage objective function in a mathematical model for controlling voltage of the wind farm based on the energy and node voltages, and then constructing constraints in the mathematical model for controlling voltage of the wind farm based on the power of wind turbines in the energy storage type wind farm and the charge and discharge power of energy storage units in the energy storage system;

[0012] S4) Solving the mathematical model of wind farm voltage control to obtain the optimal value of the charging and discharging power of the energy storage system, and adjusting the reactive output of the wind turbines and the energy storage system in the energy storage wind farm according to the optimal value of the charging and discharging power of the energy storage system.

[0013] Furthermore, the linearized branch power flow model expression in step S1) is as follows:

[0014] P i +p i+1 =P i+1

[0015] Q i +q i+1 =Q i+1

[0016]

[0017] In the above formula, P i is the sum of the active power output of the i-th wind turbine and the active power output of the i-th energy storage battery, P i , Q i The relationship is: P i +jQ i The apparent power flowing from bus i to bus i+1; p i+1 and q i+1 are the active power and reactive power of the wind turbine on bus i+1; R i 、X i The relationship is: R i +jX i The complex impedance between busbar i and busbar i+1; V0 is the voltage value on the boundary bus related to the wind farm, V i is the unit voltage.

[0018] Furthermore, the incremental model expression of the energy storage system in step S2) is as follows:

[0019] C E =C E,0 -∫P E dt-η L C E,0

[0020]

[0021]

[0022]

[0023]

[0024] In the above formula, C E is the energy stored in the energy storage system, C E,0 is the initial energy, P E is the charging and discharging power of the energy storage system, The increment of energy stored in the energy storage system, ΔP E is the increment of charging and discharging power of the energy storage system, P E,0 is the initial value of the energy storage system charging and discharging power, η L is the energy storage system loss coefficient; Δi L is the increment of the charging and discharging current of the energy storage unit, s is the preset operator, and are the proportional and integral gains of the outer loop PI controller respectively; T id is the inner loop time constant; T fd is the time constant of the DC / DC converter active filter; ΔP g is the increment of the active output of the fan, ΔP int U is the increment of the error integral between the reference value and the actual value of the wind turbine active output, E is the voltage of energy storage; is the reference power of energy storage; P g is the generator power; P int is the error integral between the energy storage reference power and the energy storage power.

[0025] Furthermore, the objective function of the first stage in step S3) is to suppress the voltage fluctuations of the medium voltage nodes and wind turbine nodes in the wind farm and reduce the distance between the energy storage system power and 50% of the rated power. The expression is as follows:

[0026]

[0027] In the above formula, They are the total power of the energy storage system at the kth moment, the total power of the energy storage system at the initial moment, and 50% of the rated power of the energy storage system; λ C is the weight of the preset energy storage energy control objective function; V is the weight of the preset voltage control objective function; T is the number of wind turbines in the wind farm; V MV-bus is the medium voltage node voltage; V WT-bus is the wind turbine node voltage; λ1 is the preset bus node voltage weight; λ2 is the preset wind turbine node voltage weight.

[0028] Furthermore, in step S3), the second-stage objective function is that each energy storage unit can achieve fair output, which is expressed as follows:

[0029]

[0030] In the above formula, C E,j (k) are the power of j energy storage units at the kth moment, the power of the energy storage unit at the initial moment, and the average power of all energy storage units; N T is the number of wind turbines in the wind farm; N p is the prediction step for optimal control.

[0031] Furthermore, the constraint condition expression in step S3) is as follows:

[0032]

[0033]

[0034]

[0035]

[0036] In the above formula, is the total available charging power of the energy storage system, is the total reference power of the energy storage system, is the total discharge power of the energy storage system, is the active power output reference value of the i-th wind turbine, is the available wind energy of the i-th wind turbine, N T is the number of wind turbines in the wind farm, is the charging power available to the i-th energy storage unit, is the reference power of the i-th energy storage unit, is the available discharge power of the i-th energy storage unit.

[0037] Furthermore, the charging power available for the i-th energy storage unit is and discharge power The expressions are:

[0038]

[0039]

[0040] In the above formula, is the available discharge energy in the discharge mode of the i-th energy storage unit, is the available discharge energy in the charging mode of the i-th energy storage unit, is the output power upper limit of the energy storage battery; Δt is the control period.

[0041] Furthermore, the available discharge energy in the discharge mode and the charging mode of the i-th energy storage unit is The expressions are:

[0042]

[0043]

[0044] In the above formula, SOC i is the state of charge of the i-th energy storage battery, SOC min and SOC max are the maximum charge value and minimum charge value of the energy storage battery respectively, is the rated capacity of the i-th energy storage battery; ξ is the preset proportional coefficient.

[0045] The present invention further provides a computer system, comprising a computer, wherein the computer is programmed or configured to execute any of the above-mentioned methods for controlling voltage of an energy storage-type wind farm based on optimal control.

[0046] The present invention further provides a computer-readable storage medium storing a computer program programmed or configured to execute any of the above-mentioned methods for controlling voltage of an energy storage-type wind farm based on optimal control.

[0047] Compared with the prior art, the advantages of the present invention are:

[0048] Based on the topological structure of an energy storage wind farm, the present invention establishes a linearized branch power flow model to determine the relationship between voltage and power in the energy storage wind farm. It then introduces an energy storage system incremental model to determine the relationship between the energy of the energy storage system and the charge and discharge power in the energy storage wind farm. This is used to construct an objective function and constraints, ultimately combining these models into a mathematical model for wind farm voltage control. This mathematical model transforms the voltage control problem of the energy storage wind farm into a quadratic programming problem. Solving this mathematical model yields the optimal charge and discharge power of the energy storage system. Based on this optimal charge and discharge power, the reactive output of the wind turbines and energy storage system in the energy storage wind farm can be coordinated to suppress node voltage fluctuations. Voltage fluctuations are effectively suppressed through the optimal coordinated power output of the wind turbine group and the distributed energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a diagram of the control configuration scheme for energy storage wind farms.

[0050] Figure 2 Schematic diagram of a flow chart according to an embodiment of the present invention.

[0051] Figure 3 FIG. 4 is a system block diagram according to an embodiment of the present invention.

[0052] Figure 4 FIG. 4 is a topological structure diagram of a DC / DC converter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby.

[0054] Energy storage has the ability to quickly charge and discharge, can dynamically absorb energy and release it in a timely manner, and is an effective means to improve the grid's ability to accept wind power. Based on the characteristics of energy storage wind farms, this embodiment proposes a voltage control method for energy storage wind farms based on optimal control. By adopting the optimal control method to suppress voltage fluctuations, the charging and discharging power of energy storage is optimized to achieve reactive support, such as Figure 2As shown, the following steps are included:

[0055] S1) constructing a linearized branch power flow model based on the topology of the energy storage wind farm to obtain the relationship between voltage and power in the energy storage wind farm;

[0056] S2) Establishing an incremental model for the energy storage system to obtain the relationship between the energy storage system's energy and the charge and discharge power in the energy storage wind farm, and thereby obtaining the state space equation of the energy storage system. When the voltage fluctuation at the wind turbine node is too large, the energy storage releases energy to help suppress the voltage fluctuation;

[0057] S3) obtaining the energy of the energy storage system in the energy storage wind farm and the node voltage of the energy storage wind farm, and constructing a first-stage objective function and a second-stage objective function of the energy storage wind farm voltage control based on optimal control based on the energy and the node voltage, and then constructing constraint conditions of the energy storage wind farm voltage control based on optimal control based on the power of the wind turbines in the energy storage wind farm and the charge and discharge power of the energy storage units in the energy storage system;

[0058] S4) A wind farm voltage control mathematical model is formed by combining the linearized branch power flow model, the energy storage system increment model, and the model of energy storage-based wind farm voltage control based on optimal control. The wind farm voltage control mathematical model is solved to obtain the optimal value of the charge and discharge power of the energy storage system. The reactive output of the wind turbines and the energy storage system in the energy storage-based wind farm is adjusted according to the optimal value of the charge and discharge power of the energy storage system.

[0059] Through the above steps, this embodiment combines the constructed linearized branch power flow model, the energy storage system incremental model, and the energy storage-based wind farm voltage control model based on optimal control into a wind farm voltage control mathematical model. First, a linearized branch power flow model for the wind farm is established. Then, the state-space equations of the energy storage system are introduced through the energy storage system incremental model. The objective function and constraints of the energy storage-based wind farm voltage control model based on optimal control are determined. Finally, a mathematical model for wind farm voltage control including energy storage-based wind turbines is obtained. This mathematical model transforms the voltage control problem of the energy storage-based wind farm into a quadratic programming problem. Solving this mathematical model yields the optimal charge and discharge power values of the energy storage system. Based on this optimal charge and discharge power value, the reactive output of the wind turbines and the energy storage system in the energy storage-based wind farm can be coordinated to suppress node voltage fluctuations. This allows the performance characteristics of the energy storage system to be utilized to optimize wind turbine control, improve voltage regulation capability, and meet control objectives by adjusting the reactive power output of both.

[0060] The topology of energy storage wind farm is as follows: Figure 3 As shown, each bus corresponds to an energy storage type wind turbine set, and each energy storage type wind turbine set consists of a one-to-one corresponding wind turbine and energy storage system. Therefore, the linearized branch power flow model expression in step S1) is as follows:

[0061]

[0062] In the above formula, P i , Q i The relationship is: P i +jQ i The apparent power flowing from bus i to bus i+1; p i+1 and q i+1 are the active power and reactive power of the wind turbine on bus i+1; R i 、X i The relationship is: R i +jX i The complex impedance between busbar i and busbar i+1; V0 is the voltage value on the boundary bus related to the wind farm, V i Is the unit voltage. Where the unit voltage V i The value range is: V i min ≤V i ≤V i max In this embodiment, V i min Set to 0.95pu, V i max Set to 1.05pu, Pi in this model is the sum of the active power output of the i-th wind turbine and the active power output of the i-th energy storage battery, that is,

[0063] In step S2 of this embodiment, the energy storage system incremental model expression (i.e., the state space equation of the energy storage system) is as follows:

[0064] C E =C E,0 -∫P E dt-η L C E,0 (2)

[0065]

[0066]

[0067]

[0068]

[0069] In the above formula, C E is the energy stored in the energy storage system, C E,0 is the initial energy, P E is the charging and discharging power of the energy storage system, The increment of energy stored in the energy storage system, ΔPE is the increment of charging and discharging power of the energy storage system, P E,0 is the initial value of the energy storage system charging and discharging power, η L is the energy storage system loss coefficient; Δi L is the increment of the charging and discharging current of the energy storage unit, s is the preset operator, and are the proportional and integral gains of the outer loop PI controller respectively; T id is the inner loop time constant; T fd is the time constant of the DC / DC converter active filter; ΔP g is the increment of the active output of the fan, ΔP int U is the increment of the error integral between the reference value and the actual value of the wind turbine active output, E is the voltage of energy storage; is the reference power of energy storage; P g is the generator power; P int is the error integral between the energy storage reference power and the energy storage power.

[0070] In step S3) of this embodiment, to express more precise meanings, parameters related to electricity and power are given superscripts and subscripts compared to corresponding parameters in the energy storage system incremental model. Therefore, the relevant parameters and expressions are all constrained by the energy storage system incremental model. Step S3) of this embodiment is described in detail below:

[0071] For an energy storage system, the state of charge (SOC) of each energy storage unit should be kept within a safe operating range. For the i-th energy storage battery in the energy storage unit, there is:

[0072] SOC min ≤SOC i ≤SOC max (7)

[0073] In the above formula, SOC i is the state of charge of the i-th energy storage battery, SOC min and SOC max are the maximum charge value and the minimum charge value of the energy storage battery, respectively, so that the energy storage battery will not consume all the energy during the control period through formula (7);

[0074] For the discharge mode of the i-th energy storage unit, the available discharge energy The expression is:

[0075]

[0076] For the charging mode of the i-th energy storage unit, the available discharge energy The expression is:

[0077]

[0078] In the above formula, SOC i is the state of charge of the i-th energy storage battery, SOC min and SOC max are the maximum charge value and minimum charge value of the energy storage battery respectively, is the rated capacity of the i-th energy storage battery; ξ is the preset proportional coefficient.

[0079] like Figure 4 As shown, the DC / DC converter in the energy storage system can operate in buck or boost mode under different IGBT switch states. Figure 4 Middle,U E is the terminal voltage, i is the charge and discharge current from the energy storage system to the DC link, u is the voltage of the DC link, i L is the charge and discharge current of the energy storage system. Considering the charge and discharge power limit of the DC / DC converter, the available charging power of the i-th energy storage unit is and discharge power The expressions are:

[0080]

[0081]

[0082] In the above formula, is the available discharge energy in the discharge mode of the i-th energy storage unit, is the available discharge energy in the charging mode of the i-th energy storage unit, is the output power upper limit of the energy storage battery; Δt is the control period.

[0083] The total available charging power of the energy storage system is and total available discharge power The expressions are:

[0084]

[0085]

[0086] In the above formula, N T is the number of wind turbines in the wind farm.

[0087] In step S3 of this embodiment, the objective function of the first stage is to suppress the voltage fluctuations of the medium voltage nodes and wind turbine nodes in the wind farm and reduce the distance between the energy storage system power and 50% of the rated power. The expression is as follows:

[0088]

[0089] In the above formula, They are the total power of the energy storage system at the kth moment, the total power of the energy storage system at the initial moment, and 50% of the rated power of the energy storage system; λ C is the weight of the preset energy storage energy control objective function; V is the weight of the preset voltage control objective function; T is the number of wind turbines in the wind farm; V MV-bus is the medium voltage node voltage; V WT-bus is the wind turbine node voltage; λ1 is the preset bus node voltage weight; λ2 is the preset wind turbine node voltage weight; V MV-bus 、V WT-bus The corresponding electrical quantity of the energy storage system and the corresponding node voltage can be measured.

[0090] In step S3 of this embodiment, the second-stage objective function is to enable each energy storage unit to achieve fair output, which is expressed as follows:

[0091]

[0092] In the above formula, C E,j (k) are the power of j energy storage units at the kth moment, the power of the energy storage unit at the initial moment, and the average power of all energy storage units; N T is the number of wind turbines in the wind farm; N p is the prediction step of optimal control. In this embodiment, N p =2. Similarly, C E,j (k) The power can be measured for the corresponding energy storage unit in the energy storage system.

[0093] In step S3) of this embodiment, the constraint condition expression is as follows:

[0094]

[0095]

[0096]

[0097]

[0098] In the above formula, is the total available charging power of the energy storage system, is the total reference power of the energy storage system, is the total discharge power of the energy storage system, is the active power output reference value of the i-th wind turbine is the available wind energy of the ith wind turbine, NT is the number of wind turbines in the wind farm, is the charging power available to the i-th energy storage unit, is the reference power of the i-th energy storage unit, is the available discharge power of the i-th energy storage unit.

[0099] In step S4 of this embodiment, the mathematical model for wind farm voltage control can be solved using a solver. Using a solver to solve optimization problems is a common practice for those skilled in the art. This solution does not involve improvements to the solver's method, and the solution process will not be described in detail here. The solver used in this embodiment is the Mosek solver.

[0100] After obtaining the optimal value of the charge and discharge power of the energy storage system, adjusting the reactive output of the wind turbine and the energy storage system according to the charge and discharge power of the energy storage system is a common method used by those skilled in the art. This solution does not involve improvements to the specific process, and the specific process of adjusting the reactive output of the wind turbine and the energy storage system according to the charge and discharge power of the energy storage system will not be repeated here.

[0101] The present invention further provides a computer system, comprising a computer, wherein the computer is programmed or configured to execute any of the above-mentioned methods for controlling voltage of an energy storage-type wind farm based on optimal control.

[0102] The present invention further provides a computer-readable storage medium storing a computer program programmed or configured to execute any of the above-mentioned methods for controlling voltage of an energy storage-type wind farm based on optimal control.

[0103] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed above with reference to the preferred embodiment, it is not intended to limit the present invention. Therefore, any simple modifications, equivalent variations, and modifications to the above embodiment that do not depart from the technical solution of the present invention and are based on the technical essence of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A voltage control method for an energy storage type wind farm based on optimal control, characterized in that: The following steps are involved: S1) Based on the topological structure of the energy storage wind farm, a linearized branch power flow model in the wind farm voltage control mathematical model is constructed to obtain the relationship between voltage and power in the energy storage wind farm; S2) Establishing an incremental model of the energy storage system in the wind farm voltage control mathematical model to obtain the relationship between the energy storage system energy and the charging and discharging power in the energy storage wind farm; S3) Obtain the energy of the energy storage system in the energy storage wind farm and the node voltage of the energy storage wind farm, and construct the first-stage objective function and the second-stage objective function in the wind farm voltage control mathematical model based on the energy and node voltage. Then, construct the constraint conditions in the wind farm voltage control mathematical model based on the power of the wind turbines in the energy storage wind farm and the charge and discharge power of the energy storage units in the energy storage system. The first-stage objective function is to suppress the voltage fluctuations of the medium-voltage nodes and wind turbine nodes in the wind farm and reduce the distance between the energy storage system power and 50% of the rated power. The expression is as follows: In the above formula, They are the total power of the energy storage system at the kth moment, the total power of the energy storage system at the initial moment, and 50% of the rated power of the energy storage system; The weight of the preset energy storage energy control objective function; The weight of the preset voltage control objective function; is the number of wind turbines in the wind farm; is the medium voltage node voltage; is the wind turbine node voltage; is the preset bus node voltage weight; is the preset wind turbine node voltage weight; The objective function of the second stage is to achieve fair output for each energy storage unit, which is expressed as follows: In the above formula, They are the power of j energy storage units at the kth moment, the power of the energy storage unit at the initial moment, and the average power of all energy storage units; is the number of wind turbines in the wind farm; is the prediction step for optimal control; S4) Solve the mathematical model of wind farm voltage control to obtain the optimal value of the charging and discharging power of the energy storage system, and adjust the reactive output of the wind turbines and the energy storage system in the energy storage wind farm based on the optimal value of the charging and discharging power of the energy storage system.

2. The voltage control method for energy storage type wind farm based on optimal control according to claim 1, characterized in that: The linearized branch power flow model expression in step S1) is as follows: In the above formula, P i is the sum of the active power output of the i-th wind turbine and the active power output of the i-th energy storage battery, The relationship is: The apparent power flowing from bus i to bus i+1 is: and Busbar Active power and reactive power of wind turbines on the The relationship is: The complex impedance between busbar i and busbar i+1; is the voltage value on the boundary bus related to the wind farm, is the unit voltage.

3. The voltage control method for energy storage type wind farm based on optimal control according to claim 1, characterized in that: The incremental model expression of the energy storage system in step S2) is as follows: In the above formula, is the energy stored in the energy storage system, is the initial energy, is the charging and discharging power of the energy storage system, The increment of energy stored in the energy storage system, is the increment of charging and discharging power of the energy storage system, is the initial value of the energy storage system charging and discharging power, is the energy storage system loss coefficient; is the increment of the charging and discharging current of the energy storage unit, is the preset operator, and are the proportional and integral gains of the outer loop PI controller respectively; is the inner loop time constant; is the time constant of the DC / DC converter active filter; is the increment of the active power output of the fan, is the increment of the error integral between the reference value and the actual value of the active output of the fan. is the voltage of energy storage; is the reference power of energy storage; is the generator power; is the error integral between the energy storage reference power and the energy storage power.

4. The voltage control method for energy storage type wind farm based on optimal control according to claim 1, characterized in that: The constraint condition expression in step S3) is as follows: In the above formula, is the total available charging power of the energy storage system, is the total reference power of the energy storage system, is the total discharge power of the energy storage system, is the active power output reference value of the i-th wind turbine, is the available wind energy of the ith wind turbine, is the number of wind turbines in the wind farm, is the charging power available to the i-th energy storage unit, is the reference power of the i-th energy storage unit, is the available discharge power of the i-th energy storage unit.

5. The voltage control method for energy storage type wind farm based on optimal control according to claim 4, characterized in that: Available charging power for the i-th energy storage unit and discharge power The expressions are: In the above formula, is the available discharge energy in the discharge mode of the i-th energy storage unit, is the available discharge energy in the charging mode of the i-th energy storage unit, The output power limit of the energy storage battery; For the control cycle.

6. The voltage control method for energy storage type wind farm based on optimal control according to claim 5, characterized in that: The available discharge energy of the i-th energy storage unit in discharge mode and charge mode 、 The expressions are: In the above formula, is the state of charge of the i-th energy storage battery, and are the maximum charge value and minimum charge value of the energy storage battery respectively, is the rated capacity of the i-th energy storage battery; is the preset scaling factor.

7. A computer system comprising a computer, characterized in that: The computer is programmed or configured to execute the energy storage type wind farm voltage control method based on optimal control according to any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program programmed or configured to execute the energy storage type wind farm voltage control method based on optimal control according to any one of claims 1 to 6.

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