A voltage regulation method and device for a battery energy storage system

Abstract

This invention discloses a voltage regulation method and apparatus for a battery energy storage system. The method includes: acquiring load demand data and photovoltaic power generation data of a distribution network, as well as state of charge (SOC) data of the battery energy storage system; performing power flow calculations on the distribution network based on the load demand data, the photovoltaic power generation data, and the SOC data to obtain voltage data for each bus node; calculating a weighted average bus voltage based on a plurality of preset constants and preset voltage reference values, combined with the voltage data; and adjusting the voltage value of the battery energy storage system based on the error between the weighted average bus voltage data and the preset voltage reference values. This method helps to solve the technical problem that traditional voltage regulation methods have limited ability to regulate voltage fluctuations when photovoltaic power has penetrated the distribution network in large quantities, thus improving the voltage regulation efficiency of the battery energy storage system.

Description

Technical Field

[0001] This invention relates to the technical field of voltage regulation in battery energy storage systems, and more particularly to a voltage regulation method and apparatus for battery energy storage systems. Background Technology

[0002] Photovoltaics (PV) is being widely integrated into the electricity demand side as a distributed energy source. Distributed generation, as a flexible resource for distribution networks, has promoted the flexibility of distribution networks, but it has also changed the net load power, network losses, voltage levels, and short-circuit fault analysis of the distribution network. However, it has also brought adverse effects to system relay protection, economic operation, and load forecasting. Currently, distributed generation supports a considerable proportion of electricity demand in some areas with abundant distributed energy resources, but the volatility of renewable energy can easily cause voltage exceedance issues. Voltage regulation is a crucial power quality issue in distribution networks, requiring the supply voltage to user terminals to be within an acceptable range. Traditional distribution systems are designed as passive networks with unidirectional power flow. With the increasing penetration of solar photovoltaic (PV), reverse power flow may occur during peak solar power generation, leading to voltage rises in the distribution system. This voltage rise problem, coupled with the intermittent nature of solar PV generation, changes the traditional voltage regulation problem. The integration of energy storage (ES) helps to mitigate the impact of distributed energy volatility, which is beneficial to the safety of power system operation. Furthermore, when PV penetration in the distribution network is high, energy storage can be used to smooth out peak and valley loads during periods of high and low electricity demand. By combining the time-of-use pricing mechanism of the electricity market, charging energy storage during off-peak hours and discharging during peak hours can achieve the best economic benefits of energy storage and effectively reduce the cost of flexible adjustment of the distribution network by energy storage.

[0003] Existing technologies for the operation and control strategies of battery energy storage integrated into high-penetration photovoltaic distribution networks mainly focus on two aspects. One is based on a single control objective, such as preventing voltage exceedances caused by photovoltaic integration into the distribution network, to obtain specific control procedures and achieve online control of energy storage. However, energy storage systems are costly, and this control strategy only aims to achieve safe and stable operation of the distribution network, not the most economical operating mode, thus hindering economic value. The other approach involves constructing an optimization model, analyzing and modeling various physical parameters under the physical scenario of high photovoltaic penetration in the distribution network, and optimizing the energy storage system configuration with the goal of minimizing system operating costs such as network losses and voltage exceedance adjustments. Solving this control strategy involves optimization analysis and relatively complex calculations, but it can take multiple objectives into account and achieve optimal system operation. Traditional equipment is rarely used in these two types of research, and if used, it is limited to situations where distributed generation lacks sufficient voltage self-regulation. The integration of traditional equipment with battery energy storage systems has not been studied in depth. In previous studies, traditional voltage regulation methods were mostly used as auxiliary regulation methods, which are limited by regulation speed and discontinuity. In situations where photovoltaics have extensively penetrated the distribution network, the means of regulating voltage fluctuations are limited, leaving room for further research and improvement.

[0004] Therefore, in order to improve the voltage regulation capability of battery energy storage systems and solve the technical problem that the existing traditional voltage regulation methods have limited ability to regulate voltage fluctuations when photovoltaics are widely integrated into the distribution network, it is urgent to construct a voltage regulation method for battery energy storage systems. Summary of the Invention

[0005] This invention provides a voltage regulation method and device for a battery energy storage system, which solves the technical problem that the existing traditional voltage regulation methods have limited ability to regulate voltage fluctuations when photovoltaics are widely integrated into the power distribution network.

[0006] In a first aspect, the present invention provides a voltage regulation method for a battery energy storage system, comprising:

[0007] Acquire load demand data and photovoltaic power generation data of the power distribution network, as well as the state of charge data of the battery energy storage system;

[0008] Based on the load demand data, the photovoltaic power generation data, and the state of charge data, power flow calculations are performed on the distribution network to obtain the voltage data of each bus node;

[0009] Based on a number of preset constants and preset voltage reference values, and combined with the voltage data, the weighted average voltage data of the bus is calculated.

[0010] The voltage value of the battery energy storage system is adjusted based on the error between the weighted average voltage data of the bus and the preset voltage reference value.

[0011] Optionally, based on a plurality of preset constants and preset voltage reference values, and in combination with the voltage data, the weighted average voltage of the bus is calculated, including:

[0012] The weight of each bus node is calculated based on the preset constants and the preset reference values.

[0013] Based on the voltage data and the weights, the weighted average voltage data of the bus is calculated.

[0014] Optionally, adjusting the voltage value of the battery energy storage system based on the error value between the bus weighted average voltage data and the preset voltage reference value includes:

[0015] The absolute value of the difference between the weighted average voltage data of the bus and the preset voltage reference value is calculated to obtain the error value;

[0016] Based on the error value, the voltage value of the battery energy storage system is adjusted.

[0017] Optionally, adjusting the voltage value of the battery energy storage system based on the error value includes:

[0018] Based on the error value, calculate the tap position information that the transformer tap changer module needs to adjust;

[0019] Adjust the tap changer module to the position corresponding to the tap position information so that the voltage value of the battery energy storage system is close to the preset voltage reference value.

[0020] Optionally, after adjusting the voltage value of the battery energy storage system based on the error value between the bus weighted average voltage data and the preset voltage reference value, the method further includes:

[0021] When the error value is greater than a preset threshold, after a preset period, the tap of the transformer is moved one unit in the error direction.

[0022] In a second aspect, the present invention provides a voltage regulating device for a battery energy storage system, comprising:

[0023] The acquisition module is used to acquire load demand data and photovoltaic power generation data of the distribution network, as well as the state of charge data of the battery energy storage system.

[0024] The calculation module is used to perform power flow calculation of the distribution network based on the load demand data, the photovoltaic power generation data and the state of charge data, and to obtain the voltage data of each bus node;

[0025] The weighting module is used to calculate the weighted average voltage data of the bus based on a number of preset constants and preset voltage reference values, combined with the voltage data.

[0026] The adjustment module is used to adjust the voltage value of the battery energy storage system based on the error value between the bus weighted average voltage data and the preset voltage reference value.

[0027] Optionally, the weighting module includes:

[0028] The weighting submodule is used to calculate the weight of each bus node based on the preset constants and the preset reference values.

[0029] The weighting submodule is used to calculate the weighted average voltage data of the bus based on the voltage data and the weights.

[0030] Optionally, the adjustment module includes:

[0031] The error submodule is used to calculate the absolute value of the difference between the weighted average voltage data of the bus and the preset voltage reference value, so as to obtain the error value;

[0032] The adjustment submodule is used to adjust the voltage value of the battery energy storage system based on the error value.

[0033] Optionally, the adjustment submodule includes:

[0034] The calculation unit is used to calculate the tap position information that the transformer's tap changer module needs to adjust based on the error value.

[0035] An adjustment unit is used to adjust the tap switch module to the position corresponding to the tap position information so that the voltage value of the battery energy storage system is close to the preset voltage reference value.

[0036] Optionally, the device further includes:

[0037] The moving module is used to move the tap of the transformer one unit in the error direction after a preset period when the error value is greater than a preset threshold.

[0038] As can be seen from the above technical solutions, the present invention has the following advantages: The present invention provides a voltage regulation method for a battery energy storage system. By acquiring load demand data and photovoltaic power generation data of the distribution network, as well as the state of charge data of the battery energy storage system, power flow calculation of the distribution network is performed based on the load demand data, the photovoltaic power generation data, and the state of charge data to obtain voltage data of each bus node. Based on multiple preset constants and preset voltage reference values, combined with the voltage data, the weighted average voltage data of the bus is calculated. Based on the error value between the weighted average voltage data of the bus and the preset voltage reference value, the voltage value of the battery energy storage system is adjusted. Through a voltage regulation method for a battery energy storage system, the technical problem of limited adjustment capability of traditional voltage regulation methods for voltage fluctuations when photovoltaics penetrate a large amount of the distribution network is solved, thereby improving the voltage regulation efficiency of the battery energy storage system. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a flowchart illustrating the steps of a voltage regulation method for a battery energy storage system according to a first embodiment of the present invention.

[0041] Figure 2 This is a flowchart illustrating the steps of a second embodiment of a voltage regulation method for a battery energy storage system according to the present invention.

[0042] Figure 3 This is a structural block diagram of an embodiment of a voltage regulation device for a battery energy storage system according to the present invention. Detailed Implementation

[0043] This invention provides a voltage regulation method and apparatus for a battery energy storage system, which addresses the technical problem that traditional voltage regulation methods have limited ability to regulate voltage fluctuations when photovoltaics are widely integrated into the power distribution network.

[0044] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0045] Example 1, please refer to Figure 1 , Figure 1 This is a flowchart illustrating the steps of a voltage regulation method for a battery energy storage system according to an embodiment of the present invention, including:

[0046] Step S101: Obtain load demand data and photovoltaic power generation data of the distribution network, as well as the state of charge data of the battery energy storage system;

[0047] It should be noted that an on-load tap-changing transformer (OLTC) is a type of transformer that can switch tap voltages while operating under load. It can guarantee the quality of the power supply voltage to users at any time, but it cannot alter the reactive power demand balance.

[0048] A battery energy storage system (BESS) is an energy storage system consisting of a battery and a parallel voltage-type converter, which has the ability to quickly regulate and exchange (output or absorb) power (active or reactive) between AC systems.

[0049] Step S102: Based on the load demand data, the photovoltaic power generation data, and the state of charge data, perform power flow calculation of the distribution network to obtain the voltage data of each bus node;

[0050] In this embodiment of the invention, the voltage data of each bus node is calculated based on the power flow calculation of the distribution network.

[0051] Step S103: Based on multiple preset constants and preset voltage reference values, and combined with the voltage data, calculate the weighted average voltage data of the bus.

[0052] In this embodiment of the invention, the weight of each bus node is calculated based on the preset multiple constants and the preset reference values, and the weighted average voltage data of the bus is calculated based on the voltage data and the weights.

[0053] Step S104: Adjust the voltage value of the battery energy storage system based on the error value between the bus weighted average voltage data and the preset voltage reference value.

[0054] In this embodiment of the invention, the absolute value of the difference between the bus weighted average voltage data and the preset voltage reference value is calculated to obtain the error value, and the voltage value of the battery energy storage system is adjusted based on the error value.

[0055] The voltage regulation method for a battery energy storage system provided in this embodiment of the invention acquires load demand data and photovoltaic power generation data of the distribution network, as well as state of charge data of the battery energy storage system. Based on the load demand data, photovoltaic power generation data, and state of charge data, power flow calculation of the distribution network is performed to obtain voltage data of each bus node. Based on multiple preset constants and preset voltage reference values, combined with the voltage data, the weighted average voltage data of the bus is calculated. Based on the error value between the weighted average voltage data of the bus and the preset voltage reference values, the voltage value of the battery energy storage system is adjusted. This voltage regulation method for a battery energy storage system solves the technical problem that the current traditional voltage regulation methods have limited ability to regulate voltage fluctuations when photovoltaics penetrate the distribution network in large quantities, thus improving the voltage regulation efficiency of the battery energy storage system.

[0056] Example 2, please refer to Figure 2 , Figure 2 The flowchart of a voltage regulation method for a battery energy storage system according to the present invention includes:

[0057] Step S201: Obtain load demand data and photovoltaic power generation data of the distribution network, as well as state of charge data of the battery energy storage system;

[0058] In this embodiment of the invention, the on-load tap-changing transformer uses a centralized controller, which collects state-of-charge data from all battery energy storage systems at each time t. ), load demand data of the load bus ( , ) and solar photovoltaic inverters collect photovoltaic power generation data ( ),in and These are the SOC (State of Charge) of the battery energy storage system on the i-th bus, the active and reactive power demand on the i-th bus, and the active power output of the solar photovoltaic system on the i-th bus.

[0059] In practice, solar photovoltaic systems cause changes in the active power of the connected bus. Due to the high R / X ratio of the distribution network, these changes lead to voltage deviations. To regulate the bus voltage, the battery energy storage system operates in active power control mode. This means that the active power output of the battery energy storage system is controlled based on the SOC (State of Charge) and the bus voltage at the connection point. The battery energy storage system controller has two modes: emergency and normal. The operating mode of the controller at any given time is selected based on the output of the mode selector block. This is based on the bus voltage at any time t and t-t. delay Emergency mode output power (P) during the period emer This ensures that when the battery storage system's emergency power supply is used to regulate the bus voltage, the emergency mode remains active until the system can maintain the bus voltage. The controller has two modes as follows.

[0060] 1) Emergency Mode: When the bus voltage is less than the relevant minimum limit (V) min or greater than the relevant maximum limit (V) max When mode=0, the battery energy storage system operates to maintain the bus voltage within the limit and continues to operate until the system is able to maintain the bus voltage within the limit. When mode=0, the mode selector block selects this mode. The active power output of the battery energy storage system is controlled by a proportional-integral (PI) controller, whose input is V. i,t and reference voltage The difference, i.e. The selection here is based on the bus voltage and battery conditions. As shown below:

[0061] ;

[0062] The depth of discharge (DOD) of a battery energy storage system is inversely proportional to the expected average number of cycles of its state of charge (SOC). Therefore, to maximize the number of charge-discharge cycles of a battery energy storage system, a fixed SOC is necessary. min and SOC max The DOD (Demand of Activation) of the battery energy storage system is limited. At each time t, the SOC (State of Charge) limiter block detects whether the SOC of the battery energy storage system exceeds its limit when the emergency power provided by the battery energy storage system equals the output of the PI controller. Therefore, the predicted SOC value is... The calculation formula is:

[0063] ;

[0064] Among them, T p This is the controller switching time, measured in seconds. It is the output of the PI controller at time t. It is the nominal voltage of BESS (Battery Energy Storage System). It is the SOC (State of Charge) data of the battery energy storage system at the previous moment, C b This is the rated capacity of the battery energy storage system. Among them, It can be represented as: =1-Mode. Based on The output of the SOC (State of Charge) limiter block is shown below:

[0065] ;

[0066] In the above situation, when When its limits are exceeded, the BESS (Battery Energy Storage System) is unable to provide the necessary P without exceeding its SOC (State of Charge) limit. emer To maintain the voltage. Therefore, the responsibility for maintaining the voltage is transferred to the OLTC (On-Load Tap Changer). In this case, both the voltage deviation term and the SOC (State of Charge) deviation term will increase, thereby increasing the total weight of the bus, as shown in Equation (1). The BESS (Battery Energy Storage System) power supply is cut off, i.e., when the predicted SOC (State of Charge) reaches its limit, P emer =0, these limits are considered hard limits, thus preventing overcharging and over-discharging of the BESS (Battery Energy Storage System). When the pressure on the system decreases, the BESS restarts and moves to the next mode—normal mode.

[0067] 2) Normal Mode: When the system is able to maintain the voltage within the required limits on its own, the BESS (Battery Energy Storage System) operates, thereby restoring the SOC (State of Charge) to its normal value through charging or discharging. ref This is when mode = 1 in the mode selector block. The BESS (Battery Energy Storage System) output power in this mode is calculated as follows:

[0068] ;

[0069] Where R is a constant depending on the thermal limit of the BESS (Battery Energy Storage System). R determines the maximum charge / discharge rate of the battery in normal mode. St is a scaling factor that ensures that the normal operation of the BESS does not cause voltage rise / fall. Therefore, S in the formula... t The calculation is as follows:

[0070] ;

[0071] in, Used to control S tThe rate of change relative to the bus voltage. For weak buses, the voltage should be lower, as a small amount of power may cause the voltage to exceed its limit, while for strong buses, the voltage should be higher.

[0072] Step S202: Based on the load demand data, the photovoltaic power generation data, and the state of charge data, perform power flow calculation of the distribution network to obtain the voltage data of each bus node;

[0073] In this embodiment of the invention, the bus voltage is calculated using load and solar energy data obtained by the system based on power flow calculations of the distribution network. Here, the power output of the BESS (Battery Energy Storage System) is ignored. Therefore, assuming the absence of a BESS, the voltage is calculated and used as an estimate for any time t. , where 1≤i≤N, and N represents the number of distribution network buses.

[0074] Step S203: Calculate the weight of each bus node based on a plurality of preset constants and the preset reference values;

[0075] In this embodiment of the invention, the weight of each bus node is calculated by combining a plurality of preset constants and preset reference values.

[0076] In the specific implementation, the weights are determined as follows: the weight of bus i at time t, i.e. The weighting equation is calculated as follows:

[0077] ;

[0078] Where k1, k2, and k3 are constants obtained through optimization methods; Indicates the estimated voltage at bus i ( ) and its reference value (V) ref ) deviation, that is ;dir indicates the direction of movement of SOC (State of Charge) relative to voltage. This indicates the deviation of the SOC (State of Charge) of the BESS (Battery Energy Storage System) at bus i from its reference value. The deviation between them is expressed by the following equation:

[0079] ;

[0080] dir represents the direction of shift of SOC (State of Charge) relative to voltage. The equation for calculating the direction of shift is shown below:

[0081] ;

[0082] The combination of the above two equations (the deviation equation and the direction of movement calculation equation) can serve as an indicator of the voltage regulation availability of a battery energy storage system. This is because if the voltage deviation and the SOC (State of Charge) deviation show similar signs, the greater the deviation of the battery energy storage system from the reference value, the less power can be extracted without violating its SOC limits. However, if the voltage deviation and the SOC deviation have different signs, power can be extracted from the battery energy storage system for voltage regulation, thereby reducing the weight of a specific bus.

[0083] Regarding the determination of multiple constants k1, k2, and k3:

[0084] The weighting equation is crucial for determining the involvement of voltage deviation and SOC (State of Charge) deviation in the voltage regulation of a battery energy storage system. From the weighting equation, a higher k1 indicates that the bus weight primarily depends on the voltage deviation. Similarly, a higher k2 indicates that the bus weight primarily depends on the SOC deviation of the battery energy storage system. Regardless of the voltage and SOC deviations, a larger k3 provides a constant weight for all buses. The required balance between k1, k2, and k3 can be achieved by using their optimal values, thus minimizing the voltage deviation and the operating costs of the battery energy storage system. However, while attempting to minimize one, another increases; therefore, a multi-objective optimization problem is proposed. Genetic algorithms (GA) are used to solve this problem. GA can simultaneously search different regions of the solution space without sorting or weighing objectives, making it suitable for solving multi-objective problems. The specific operation is as follows:

[0085] 1) Obtain day-ahead load forecasts and solar data. Longer timeframes of data, such as data from a month ago or year ago, can be used here, but the uncertainty between actual and forecast values ​​increases with the duration.

[0086] 2) Define the constants k1, k2, and k3 in the weighting equation as control parameters for the GA in the optimization program. These control parameters determine which variables need to be changed to obtain the optimal solution.

[0087] 3) To compare the obtained solutions, the two objective functions in GA are as follows:

[0088] ;

[0089] ;

[0090] in, and These represent the voltage at bus i at instant t and the SOC (State of Charge) of the battery energy storage system at bus i (if it exists), respectively, obtained using the constants k1, k2, and k3 of the on-load tap-changing transformer. N BESS The number of BESS (Battery Energy Storage Systems) is represented by T, and the total duration is represented by T.

[0091] To include limits on bus voltage and the number of tap operations of the on-load tap-changing transformer, OB1 is further appended to include penalty factors pf1, pf2, and pf3 for voltage rise / fall, as well as the number of operations of the on-load tap-changing transformer, as follows:

[0092] ;

[0093] ;

[0094] ;

[0095] in, This refers to the total number of on-load tap-changing transformers in operation. pf1 and pf2 only apply to voltage violations of their respective V values. max or V min The busbars are evaluated. The overall goal of GA is: and By minimizing OB1, the solution with the minimum system voltage deviation and the fewest OLTC (On-Load Tap Changer) operations is obtained. Therefore, minimizing OB1 will result in minimizing voltage regulation and OLTC utilization. By minimizing OB2, the solution with the minimum deviation of the battery energy storage system from the fixed reference value's SOC (State of Charge) is obtained. Since the performance comparison of the battery energy storage system is based on charge-discharge cycle kilowatt-hours, OB2 represents the battery capacity required in the proposed method.

[0096] 4) For the optimization variables k1, k2, and k3, solve the multi-objective optimization problem using OB1 and OB2 as fuzzy functions. Here, for each set of values ​​of k1, k2, and k3, OB1 and OB2 are obtained through power flow calculations of the distribution network, while also considering the controller model.

[0097] 5) Generate a Pareto optimal solution set. The optimal values ​​of k1, k2, and k3 are selected from this set based on the objective by assigning a rank to each solution using the following method:

[0098] ;

[0099] ;

[0100] ;

[0101] The ranks obtained above represent the distance between each set of solutions and the best (minimum) solution based on each objective. Therefore, the lower the rank of a solution, the better the solution. Based on these ranks, the solutions k1, k2, and k3 with the minimum rank are selected as the final solutions.

[0102] Step S204: Based on the voltage data and the weights, calculate the weighted average voltage data of the bus.

[0103] In this embodiment of the invention, the weighted average voltage data of the bus is calculated using voltage data and weights.

[0104] In practical implementation, the weighted average voltage is: weighted average voltage The calculation formula is:

[0105] ;

[0106] in, The weight at point i on the bus at time t. Indicates the estimated voltage at bus i ( ) and its reference value (V) ref ) deviation, that is At any time t, this weighted average voltage is used as the control voltage for the on-load tap-changing transformer.

[0107] Step S205: Calculate the absolute value of the difference between the weighted average voltage data of the bus and the preset voltage reference value to obtain the error value;

[0108] In this embodiment of the invention, the absolute value of the difference between the bus weighted average voltage data and the preset voltage reference value is determined as the error value.

[0109] In the specific implementation, the weighted average voltage is... Compared with reference value V ref The comparison generates an error value. This error value is used to calculate the required tap position of the tap changer module to maintain the control voltage of the on-load tap changer transformer. Approaching V ref .

[0110] Step S206: Adjust the voltage value of the battery energy storage system based on the error value;

[0111] In an optional embodiment, adjusting the voltage value of the battery energy storage system based on the error value includes:

[0112] Based on the error value, calculate the tap position information that the transformer tap changer module needs to adjust;

[0113] Adjust the tap changer module to the position corresponding to the tap position information so that the voltage value of the battery energy storage system is close to the preset voltage reference value.

[0114] In this embodiment of the invention, based on the error value, the tap position information that the transformer tap changer module needs to be adjusted is calculated, and the tap changer module is adjusted to the position corresponding to the tap position information so that the voltage value of the battery energy storage system is close to the preset voltage reference value.

[0115] In an optional embodiment, after adjusting the voltage value of the battery energy storage system based on the error value, the method further includes:

[0116] When the error value is greater than a preset threshold, after a preset period, the tap of the transformer is moved one unit in the error direction.

[0117] In this embodiment of the invention, the formula for calculating the error value is e=V ref - The operation of on-load tap-changing transformers uses a traditional dead-zone-based method, where half of the dead zone is set as a preset threshold. If the error value e exceeds half of the dead zone, the tap of the on-load tap-changing transformer moves one unit in the error direction after a suitable preset waiting period.

[0118] The pre-set period and dead-time comparator block avoids issues caused by weighted average voltage. This helps prevent unnecessary movement of the on-load tap-changing transformer caused by transients and to prevent oscillations in the tap position of the on-load tap-changing transformer.

[0119] In practical implementation, the weighting equations ensure that weak buses requiring immediate OLTC (On-Load Tap Changer) action for voltage regulation receive higher priority. This identification of weak buses can be demonstrated as follows: Assume two buses, A and B, experiencing overvoltage / undervoltage conditions, meaning both buses have high voltage deviations. For bus A, assume a low SOC (State of Charge) deviation, meaning a BESS (Battery Energy Storage System) can ensure voltage regulation at that moment. For bus B, assume a large SOC deviation. There are two possibilities. The first possibility is that the SOC and voltage deviations have similar characteristics. In this case, it's clear that any further use of the BESS could lead to saturation. Therefore, the weighting equations and the direction-of-motion calculation equations ensure that the voltage of bus B has a higher weight in the calculation than the voltage of bus A, thus initiating OLTC action to improve voltage regulation at bus B. The second possibility is when the SOC and voltage deviations have different characteristics. Under this possibility, it can be inferred that the availability of the BESS (Battery Energy Storage System) at bus B is higher than that at bus A. Therefore, the bus B voltage has a lower weight in the calculation than the bus A voltage, resulting in the OLTC (On-Load Tap Changer) improving voltage regulation at bus A.

[0120] The voltage regulation method for a battery energy storage system provided in this embodiment of the invention acquires load demand data and photovoltaic power generation data of the distribution network, as well as state of charge data of the battery energy storage system. Based on the load demand data, photovoltaic power generation data, and state of charge data, power flow calculation of the distribution network is performed to obtain voltage data of each bus node. Based on multiple preset constants and preset voltage reference values, combined with the voltage data, the weighted average voltage data of the bus is calculated. Based on the error value between the weighted average voltage data of the bus and the preset voltage reference values, the voltage value of the battery energy storage system is adjusted. This voltage regulation method for a battery energy storage system solves the technical problem that the current traditional voltage regulation methods have limited ability to regulate voltage fluctuations when photovoltaics penetrate the distribution network in large quantities, thus improving the voltage regulation efficiency of the battery energy storage system.

[0121] Please see Figure 3 , Figure 3 This is a structural block diagram of an embodiment of a voltage regulation device for a battery energy storage system according to the present invention, comprising:

[0122] The acquisition module 301 is used to acquire load demand data and photovoltaic power generation data of the distribution network, as well as the state of charge data of the battery energy storage system.

[0123] The calculation module 302 is used to perform power flow calculation of the distribution network based on the load demand data, the photovoltaic power generation data and the state of charge data, and to obtain the voltage data of each bus node;

[0124] The weighting module 303 is used to calculate the bus weighted average voltage data based on a number of preset constants and preset voltage reference values, combined with the voltage data.

[0125] The adjustment module 304 is used to adjust the voltage value of the battery energy storage system based on the error value between the bus weighted average voltage data and the preset voltage reference value.

[0126] In an optional embodiment, the weighting module 303 includes:

[0127] The weighting submodule is used to calculate the weight of each bus node based on the preset constants and the preset reference values.

[0128] The weighting submodule is used to calculate the weighted average voltage data of the bus based on the voltage data and the weights.

[0129] In an optional embodiment, the adjustment module 304 includes:

[0130] The error submodule is used to calculate the absolute value of the difference between the weighted average voltage data of the bus and the preset voltage reference value, so as to obtain the error value;

[0131] The adjustment submodule is used to adjust the voltage value of the battery energy storage system based on the error value.

[0132] In an optional embodiment, the adjustment submodule includes:

[0133] The calculation unit is used to calculate the tap position information that the transformer's tap changer module needs to adjust based on the error value.

[0134] An adjustment unit is used to adjust the tap switch module to the position corresponding to the tap position information so that the voltage value of the battery energy storage system is close to the preset voltage reference value.

[0135] In an optional embodiment, the apparatus further includes:

[0136] The moving module is used to move the tap of the transformer one unit in the error direction after a preset period when the error value is greater than a preset threshold.

[0137] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0138] In the several embodiments provided in this application, it should be understood that the methods and apparatus disclosed in this invention can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between devices or units, and may be electrical, mechanical, or other forms.

[0139] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0140] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0141] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a readable storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned readable storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0142] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A voltage regulation method for a battery energy storage system, characterized in that, include: Acquire load demand data and photovoltaic power generation data of the power distribution network, as well as the state of charge data of the battery energy storage system; Based on the load demand data, the photovoltaic power generation data, and the state of charge data, power flow calculations are performed on the distribution network to obtain the voltage data of each bus node; Based on a number of preset constants and preset voltage reference values, and combined with the voltage data, the weighted average voltage data of the bus is calculated. The voltage value of the battery energy storage system is adjusted based on the error value between the weighted average voltage data of the bus and the preset voltage reference value. Based on multiple preset constants and preset voltage reference values, and combined with the voltage data, the weighted average voltage of the bus is calculated, including: The weight of each bus node is calculated based on the preset constants and the preset reference values. Based on the voltage data and the weights, the weighted average voltage data of the bus is calculated. The equation for calculating the weights is as follows: In the formula: The weight of bus i at time t is represented; k1, k2, and k3 are constants obtained by using optimization methods. This represents the estimated voltage at bus i at time t. Its reference value deviation, that is ;dir indicates the direction of movement of the state of charge (SOC) data relative to the voltage. This represents the State of Charge (SOC) data of the Battery Energy Storage System (BESS) at bus i. Its reference value Deviation between; Among them, deviation The calculation equation is shown below: The equation for calculating the movement direction dir is as follows: 。 2. The voltage regulation method for a battery energy storage system according to claim 1, characterized in that, Based on the error value between the bus weighted average voltage data and the preset voltage reference value, the voltage value of the battery energy storage system is adjusted, including: The absolute value of the difference between the weighted average voltage data of the bus and the preset voltage reference value is calculated to obtain the error value; Based on the error value, the voltage value of the battery energy storage system is adjusted.

3. The voltage regulation method for a battery energy storage system according to claim 2, characterized in that, Based on the error value, the voltage value of the battery energy storage system is adjusted, including: Based on the error value, calculate the tap position information that the transformer tap changer module needs to adjust; Adjust the tap changer module to the position corresponding to the tap position information so that the voltage value of the battery energy storage system is close to the preset voltage reference value.

4. The voltage regulation method for a battery energy storage system according to claim 1, characterized in that, After adjusting the voltage value of the battery energy storage system based on the error value between the bus weighted average voltage data and the preset voltage reference value, the system further includes: When the error value is greater than a preset threshold, after a preset period, the transformer tap is moved one unit in the error direction.

5. A voltage regulating device for a battery energy storage system, characterized in that, include: The acquisition module is used to acquire load demand data and photovoltaic power generation data of the distribution network, as well as the state of charge data of the battery energy storage system. The calculation module is used to perform power flow calculation of the distribution network based on the load demand data, the photovoltaic power generation data and the state of charge data, and to obtain the voltage data of each bus node; The weighting module is used to calculate the weighted average voltage data of the bus based on a number of preset constants and preset voltage reference values, combined with the voltage data. The adjustment module is used to adjust the voltage value of the battery energy storage system based on the error value between the bus weighted average voltage data and the preset voltage reference value. The weighting module includes: The weighting submodule is used to calculate the weight of each bus node based on the preset constants and the preset reference values. The weighting submodule is used to calculate the weighted average voltage data of the bus based on the voltage data and the weights. The equation for calculating the weights is as follows: In the formula: The weight of bus i at time t is represented; k1, k2, and k3 are constants obtained by using optimization methods. This represents the estimated voltage at bus i at time t. Its reference value deviation, that is ;dir indicates the direction of movement of the state of charge (SOC) data relative to the voltage. This represents the State of Charge (SOC) data of the Battery Energy Storage System (BESS) at bus i at time t. Its reference value Deviation between; Among them, deviation The calculation equation is shown below: The equation for calculating the movement direction dir is as follows: 。 6. The voltage regulating device for the battery energy storage system according to claim 5, characterized in that, The adjustment module includes: The error submodule is used to calculate the absolute value of the difference between the weighted average voltage data of the bus and the preset voltage reference value, so as to obtain the error value; The adjustment submodule is used to adjust the voltage value of the battery energy storage system based on the error value.

7. The voltage regulating device for a battery energy storage system according to claim 6, characterized in that, The adjustment submodule includes: The calculation unit is used to calculate the tap position information that the transformer's tap changer module needs to adjust based on the error value. An adjustment unit is used to adjust the tap switch module to the position corresponding to the tap position information so that the voltage value of the battery energy storage system is close to the preset voltage reference value.

8. The voltage regulating device for the battery energy storage system according to claim 5, characterized in that, The device further includes: The moving module is used to move the transformer tap one unit in the error direction after a preset period when the error value is greater than a preset threshold.

Images