A strategy and device for controlling voltage overruns in low-voltage distribution networks

Abstract

This invention discloses a strategy and apparatus for mitigating voltage exceedances in low-voltage distribution networks, relating to the field of low-voltage power grid technology. The strategy includes collecting outer-loop voltage data, inner-loop current data, inverter design parameter data, and energy storage battery data. Based on the outer-loop voltage data, inner-loop current data, and inverter design parameter data, it calculates reactive current reference data, the inverter's target total output current when outputting the reactive current reference data, and the inverter's target output AC voltage amplitude data. By adding an energy storage battery in conjunction with the inverter, when the inverter's own reactive power support is insufficient to stabilize the power grid, the energy storage battery provides additional reactive power support to the distribution network, improving the inverter's stability range against power grid fluctuations. Simultaneously, it analyzes the charging and discharging efficiency of the energy storage battery and the cost-saving effect caused by charging and discharging, minimizing the cost loss while ensuring grid voltage stability.

Description

Technical Field

[0001] This invention relates to the field of low-voltage power grid technology, and more specifically to a strategy and apparatus for managing voltage overruns in low-voltage distribution networks. Background Technology

[0002] Low-voltage power grids are susceptible to fluctuations in the upstream power grid and distributed power generation output, which can easily lead to voltage fluctuations and voltage exceeding limits. To ensure that the voltage of the low-voltage power grid fluctuates within the normal range, SVG (Static Var Generator) is generally used to compensate for reactive power in the low-voltage power grid to ensure voltage stability. However, the compensation capacity of SVG is limited. Its operation must prioritize the stability of its own DC bus voltage. When the reactive power to be compensated causes its DC bus voltage to exceed the limit, it will reduce or even suspend the reactive power support of the power grid. The prior art disclosed in CN112583020A presents a two-stage voltage control method for low-voltage distribution networks, comprising the following steps: Step 1: Selecting the dominant node of the low-voltage distribution network and monitoring its voltage; Step 2: Determining whether the voltage of the dominant node exceeds the limit. If so, updating the capacity utilization rate of the remaining photovoltaic inverters in the low-voltage distribution network based on the capacity utilization rate of the photovoltaic inverters on the dominant node, thereby controlling the voltage of the low-voltage distribution network by adjusting the reactive power of the remaining photovoltaic inverters; Step 3: Determining whether the voltage of the dominant node exceeds the limit. If so, updating the availability rate of the remaining energy storage systems based on the utilization rate of the energy storage system on the dominant node and combined with local control, thereby controlling the voltage of the low-voltage distribution network by adjusting the active power output of the remaining energy storage systems. This prior art improves the safety and economy of vulnerable low-voltage distribution systems by utilizing the fair participation of various devices in voltage regulation and effectively ensuring that the voltage is within a safe threshold.

[0003] Although the aforementioned existing technologies have improved voltage regulation capabilities through the cooperation of photovoltaic inverters and energy storage systems, there are still some limitations. The charging and discharging of energy storage systems have a certain conversion efficiency, meaning that some energy is lost during both charging and discharging. Furthermore, energy storage systems have a limited lifespan, i.e., a limited number of charging cycles. Over-reliance on energy storage systems can easily lead to excessive wear and tear, resulting in higher costs. Summary of the Invention

[0004] The purpose of this invention is to provide a strategy and apparatus for managing voltage overruns in low-voltage distribution networks, thereby addressing the aforementioned shortcomings in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a strategy for controlling voltage overshoot in low-voltage distribution networks, comprising the following steps:

[0006] S1. Collect voltage outer loop data, current inner loop data, inverter design parameter data, and energy storage battery data. When collecting voltage outer loop data, this includes acquiring the three-phase grid voltage at the grid connection point or inverter AC output terminal using a voltage sensor; acquiring voltage reference values ​​through an upper-level control system (such as a power plant energy management system) or local fixed setpoints; and calculating the real-time phase angle and fundamental frequency of the grid voltage using a PLL based on the acquired three-phase grid voltage. When collecting current inner loop data using a current sensor, this includes acquiring the three-phase output current at the inverter AC output terminal; acquiring the inverter's active current reference value (i.e., d-axis current reference value) through the MPPT's maximum power point current command, active power dispatch command, or the output of the DC bus voltage control loop; acquiring the real-time phase angle; and acquiring the inverter DC bus voltage across the inverter's DC-side capacitors using a voltage sensor. When collecting inverter design parameter data, this includes calculating the rated peak current by acquiring the effective value of the rated current from the inverter nameplate parameters; calculating the upper limit of AC voltage amplitude by the maximum modulation ratio; and acquiring the inverter output filter reactance, etc., from the inverter design parameters. Energy storage battery data includes charging efficiency, discharging efficiency, current SOC, optimal SOC operating point, maximum SOC change rate, maximum charging / discharging power, minimum charging / discharging power, rated capacity of the energy storage battery, control cycle, cumulative charging / discharging amount, basic aging coefficient, loss coefficient, energy loss cost coefficient (RMB / kW), battery aging cost coefficient (RMB / kWh), and SOC offset penalty coefficient (RMB / kWh). ), power grid regulation penalty coefficient (yuan / ).

[0007] S2. Based on the voltage outer loop data, current inner loop data and inverter design parameter data, calculate the reactive current reference data, the inverter target output total current and the inverter target output AC voltage amplitude data when the inverter outputs the reactive current reference data.

[0008] S3. Based on the voltage outer loop data, current inner loop data, and inverter design parameter data, perform reactive current gap calculation processing to meet the reactive current compensation requirements for maintaining low-voltage grid voltage stability; based on the reactive current gap and the energy storage battery data, perform minimum energy storage battery operation equivalent cost analysis processing to meet the reactive current compensation requirements for maintaining low-voltage grid voltage stability, and generate energy storage battery charging and discharging power data.

[0009] S4. Based on the inverter design parameter data and the energy storage battery charging and discharging power data, update the active current input to the inverter to generate inverter input analysis data.

[0010] S5. Based on the voltage outer loop data, current inner loop data, inverter design parameter data, and energy storage battery charging and discharging power data, perform three-phase modulation voltage data analysis and processing to maintain the stability of the low-voltage grid voltage by the inverter, and generate three-phase modulation voltage analysis data.

[0011] S6. Construct voltage over-limit management data and perform grid voltage over-limit management operations based on the voltage over-limit management data.

[0012] Furthermore, S2 includes the following steps:

[0013] S21. Based on the voltage outer loop data, perform reactive current reference value calculation and processing to generate reactive current reference data;

[0014] S22. Based on the current inner loop data and reactive current reference data, calculate the inverter's target total output current when the inverter outputs the reactive current reference data.

[0015] S23. Based on the voltage outer loop data, reactive current reference data and inverter design parameter data, calculate the inverter target output AC voltage amplitude data when the inverter outputs the reactive current reference data.

[0016] S24. Determine whether the total target output current of the inverter is less than or equal to the set rated peak current, and whether the target output AC voltage amplitude data of the inverter is less than or equal to the set AC voltage amplitude upper limit.

[0017] S25. If both are true, the inverter meets the reactive power compensation requirement for maintaining the stability of the low-voltage grid voltage and does not require the energy storage battery to discharge. Otherwise, it does not meet the requirement and the energy storage battery needs to discharge.

[0018] Furthermore, S3 includes the following steps:

[0019] S31. Based on the current inner loop data, inverter design parameter data, and reactive current reference data, calculate the reactive current gap and generate reactive current gap data. ,in, , This is the reactive current reference data. This is the rated peak current of the inverter. This refers to the photovoltaic input power (taking a photovoltaic grid-connected inverter as an example). This is the DC bus voltage;

[0020] S32. Based on the energy storage battery data, reactive current deficit data, and current electricity price data, construct an equivalent cost function for energy storage battery operation that meets the reactive power compensation requirements for maintaining low-voltage grid voltage stability, including the following formula:

[0021] Equivalent cost function for discharging an energy storage battery:

[0022] ,

[0023] Equivalent cost function for charging energy storage batteries:

[0024] ,

[0025] Constraints:

[0026] ,

[0027] in, The power loss cost coefficient (yuan / kW) Battery aging cost coefficient (yuan / kWh) SOC offset penalty coefficient (yuan / ), The grid regulation penalty coefficient (yuan / ), For energy storage battery charging and discharging power, and Discharge efficiency and charging efficiency, respectively and These represent the minimum charge / discharge power and the maximum charge / discharge power of the energy storage battery, respectively. and These represent the minimum and maximum SOC values ​​of the energy storage battery, respectively. To control the cycle, The maximum rate of change of SOC;

[0028] S33, if the above If the value is greater than zero, the equivalent cost function of the energy storage battery discharge is selected for minimization to generate minimum cost and corresponding charge / discharge power data; if the reactive current reference data is greater than zero, the equivalent cost function of the energy storage battery charging is selected for minimization to generate minimum cost and corresponding charge / discharge power data. When performing the minimization solution, methods such as the golden section method or gradient descent method can be used.

[0029] Furthermore, the method also includes processing the parameters in S32. , , , and To perform an update, the following steps are required:

[0030] Collect the cumulative charge and discharge amount of the energy storage battery and real-time electricity price ;

[0031] Based on formula Regarding the Update The initial power loss cost coefficient (yuan / kW);

[0032] Based on formula Regarding the Update The initial battery aging cost coefficient (yuan / kWh) is given. The aging factor of the energy storage battery (% / kWh);

[0033] Based on formula Regarding the Update Initial grid regulation penalty coefficient (yuan / ), This is the voltage deviation growth factor. This is the DC bus voltage. This is the standard voltage for the DC bus.

[0034] Based on formula and right and Update, among which and These represent the initial charging efficiency and the initial discharging efficiency, respectively. , , These are the charge / discharge efficiency control coefficients, respectively.

[0035] Furthermore, S4 includes the following steps:

[0036] S41. Based on the minimum cost and the corresponding charge / discharge power data, update the inverter's input power to generate an updated inverter input power. For example, taking a photovoltaic grid-connected inverter as an example. This means that the photovoltaic input power of the inverter is adjusted only when the energy storage battery is discharging;

[0037] S42. Collect and combine the charge / discharge power data and inverter input update power from the minimum cost and corresponding charge / discharge power data to generate inverter input power analysis data.

[0038] Furthermore, S5 includes the following steps:

[0039] S51. Based on the voltage outer loop data, current inner loop data, and inverter design parameter data, perform three-phase modulation voltage data analysis and processing to maintain the stability of the low-voltage grid voltage, and generate initial three-phase modulation voltage analysis data. Specifically, this includes the following steps: Based on the collected three-phase output current and real-time phase angle, convert them into components in the rotating coordinate system, namely d-axis current and q-axis current, through Clark transformation and Park transformation. Based on the d-axis current, q-axis current, active current reference value, and calculated reactive current reference data, calculate the current deviation of the d-axis and q-axis and input them into the current inner loop PI controller to obtain the voltage command components in the rotating coordinate system, namely d-axis reference voltage and q-axis reference voltage. Dynamic performance and anti-disturbance capability can be improved by adding feedforward decoupling terms and grid voltage feedforward. Then, transform the d-axis reference voltage and q-axis reference voltage into three-phase stationary coordinate system reference voltage through Park transformation and Clark transformation. Generate three-phase modulation voltage analysis data based on SPWM (sinusoidal pulse width modulation) and SVPWM (space vector pulse width modulation) combined with DC bus voltage.

[0040] S52. Based on the DC bus equivalent impedance, DC bus standard voltage, and the charging and discharging power data in the minimum cost and corresponding charging and discharging power data, the initial three-phase modulation voltage analysis data is adjusted to generate three-phase modulation voltage analysis data. How to adjust the three-phase modulation voltage of the inverter based on the charging and discharging power of the energy storage battery is common knowledge to those skilled in the art, and it is directly applied here without modification. Therefore, it will not be described in detail in this technical solution, and it will not cause any trouble to those skilled in the art.

[0041] Furthermore, S6 includes the following steps:

[0042] S61. Collect and combine the energy storage battery charging and discharging power data, inverter input analysis data and three-phase modulation voltage analysis data to generate voltage over-limit management data.

[0043] S62. Based on the inverter input analysis data in the voltage over-limit management data, the charging and discharging of the energy storage battery and the active power input of the inverter are managed respectively, and the modulation voltage output of the inverter is managed based on the three-phase modulation voltage analysis data.

[0044] A device for controlling voltage overruns in low-voltage distribution networks includes an interface, a storage unit, a processor, and a controller.

[0045] The interface is used to input the collected voltage outer loop data, current inner loop data, inverter design parameter data, energy storage battery data, DC bus equivalent impedance and DC bus standard voltage into the storage device.

[0046] The storage device is also used to store computer programs;

[0047] The processor is used to execute the computer program to implement a strategy for managing voltage overruns in low-voltage distribution networks;

[0048] The controller is used to perform grid voltage over-limit management operations based on the voltage over-limit management data.

[0049] 1. Compared with the prior art, the present invention provides a strategy and device for managing voltage overruns in low-voltage distribution networks. By adding energy storage batteries in conjunction with the inverter, when the reactive power support of the inverter itself is insufficient to stabilize the power grid, the energy storage batteries provide additional reactive power support to the distribution network, thereby improving the inverter's stability range against power grid fluctuations.

[0050] 2. Compared with the prior art, the present invention provides a strategy and device for managing voltage overruns in low-voltage distribution networks. By using energy storage batteries to ensure grid voltage stability, the present invention analyzes the charging and discharging efficiency of the energy storage batteries and the cost-saving effect caused by the loss of lifespan due to charging and discharging, thereby reducing cost losses while ensuring grid voltage stability. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0052] Figure 1 A strategy step diagram provided for an embodiment of the present invention;

[0053] Figure 2 This is a structural block diagram of the device provided in an embodiment of the present invention. Detailed Implementation

[0054] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0055] Exemplary embodiments will be described more fully below with reference to the accompanying drawings; however, these exemplary embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will enable those skilled in the art to fully understand the scope of this disclosure.

[0056] Where there is no conflict, the various embodiments of this disclosure and the features thereof in the embodiments may be combined with each other.

[0057] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0058] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded.

[0059] The embodiments described herein can be described with reference to plan views and / or cross-sectional views using the ideal schematic diagrams of this disclosure. Therefore, the example illustrations can be modified according to manufacturing techniques and / or tolerances. Therefore, the embodiments are not limited to those shown in the drawings, but include modifications to configurations formed based on manufacturing processes. Therefore, the areas illustrated in the drawings are schematic in nature, and the shapes of the areas shown in the figures illustrate specific shapes of areas of an element, but are not intended to be limiting.

[0060] Please see Figure 1 A strategy for managing voltage overruns in low-voltage distribution networks includes the following steps:

[0061] S1. Collect voltage outer loop data, current inner loop data, inverter design parameter data, and energy storage battery data. When collecting voltage outer loop data, this includes acquiring the three-phase grid voltage at the grid connection point or inverter AC output terminal using a voltage sensor; acquiring voltage reference values ​​through an upper-level control system (such as a power plant energy management system) or local fixed setpoints; and calculating the real-time phase angle and fundamental frequency of the grid voltage using a PLL based on the acquired three-phase grid voltage. When collecting current inner loop data using a current sensor, this includes acquiring the three-phase output current at the inverter AC output terminal; acquiring the inverter's active current reference value (i.e., d-axis current reference value) through the MPPT's maximum power point current command, active power dispatch command, or the output of the DC bus voltage control loop; acquiring the real-time phase angle; and acquiring the inverter DC bus voltage across the inverter's DC-side capacitors using a voltage sensor. When collecting inverter design parameter data, this includes calculating the rated peak current by acquiring the effective value of the rated current from the inverter nameplate parameters; calculating the upper limit of AC voltage amplitude by the maximum modulation ratio; and acquiring the inverter output filter reactance, etc., from the inverter design parameters. Energy storage battery data includes charging efficiency, discharging efficiency, current SOC, optimal SOC operating point, maximum SOC change rate, maximum charging / discharging power, minimum charging / discharging power, rated capacity of the energy storage battery, control cycle, cumulative charging / discharging amount, basic aging coefficient, loss coefficient, energy loss cost coefficient (RMB / kW), battery aging cost coefficient (RMB / kWh), and SOC offset penalty coefficient (RMB / kWh). ), power grid regulation penalty coefficient (yuan / ).

[0062] S2. Based on the voltage outer loop data, current inner loop data, and inverter design parameter data, calculate the reactive current reference data, the inverter target total output current when the inverter output reactive current reference data is obtained, and the inverter target output AC voltage amplitude data, including the following steps:

[0063] S21. Calculate and process reactive current reference values ​​based on voltage outer loop data to generate reactive current reference data.

[0064] S22. Based on the current inner loop data and reactive current reference data, calculate the inverter's target total output current when the inverter outputs reactive current reference data.

[0065] S23. Based on the voltage outer loop data, reactive current reference data and inverter design parameter data, calculate the inverter target output AC voltage amplitude data when the inverter output reactive current reference data is used.

[0066] S24. Determine whether the target total output current of the inverter is less than or equal to the set rated peak current, and whether the target output AC voltage amplitude data of the inverter is less than or equal to the set AC voltage amplitude upper limit.

[0067] S25. If both are true, the inverter meets the reactive power compensation requirement for maintaining the stability of the low-voltage grid voltage and does not require the energy storage battery to discharge. Otherwise, it does not meet the requirement and the energy storage battery needs to discharge.

[0068] S3. Based on the voltage outer loop data, current inner loop data, and inverter design parameter data, perform reactive current gap calculation for the reactive power compensation requirement to maintain low-voltage grid voltage stability; based on the reactive current gap and energy storage battery data, perform minimum energy storage battery operation equivalent cost analysis to meet the reactive power compensation requirement to maintain low-voltage grid voltage stability, and generate energy storage battery charging and discharging power data, including the following steps:

[0069] S31. Based on the current inner loop data, inverter design parameter data, and reactive current reference data, calculate the reactive current gap and generate reactive current gap data. ,in, , This is the reactive current reference data. This is the rated peak current of the inverter. This refers to the photovoltaic input power (taking a photovoltaic grid-connected inverter as an example). This is the DC bus voltage;

[0070] S32. Based on energy storage battery data, reactive current deficit data, and current electricity price data, construct an equivalent cost function for energy storage battery operation that meets the reactive power compensation requirements for maintaining low-voltage grid voltage stability, including the following formula:

[0071] Equivalent cost function for discharging an energy storage battery:

[0072] ,

[0073] Equivalent cost function for charging energy storage batteries:

[0074] ,

[0075] Constraints:

[0076] ,

[0077] in, The power loss cost coefficient (yuan / kW) Battery aging cost coefficient (yuan / kWh) SOC offset penalty coefficient (yuan / ), The grid regulation penalty coefficient (yuan / ), For energy storage battery charging and discharging power, and Discharge efficiency and charging efficiency, respectively and These represent the minimum charge / discharge power and the maximum charge / discharge power of the energy storage battery, respectively. and These represent the minimum and maximum SOC values ​​of the energy storage battery, respectively. To control the cycle, The maximum rate of change of SOC;

[0078] right , , , and To perform an update, the following steps are required:

[0079] Collect the cumulative charge and discharge volume of the energy storage battery and real-time electricity price ;

[0080] Based on formula right Update The initial power loss cost coefficient (yuan / kW);

[0081] Based on formula right Update The initial battery aging cost coefficient (yuan / kWh) is given. The aging factor of the energy storage battery (% / kWh);

[0082] Based on formula right Update Initial grid regulation penalty coefficient (yuan / ), This is the voltage deviation growth factor. This is the DC bus voltage. This is the standard voltage for the DC bus.

[0083] Based on formula and right and Update, among which and These represent the initial charging efficiency and the initial discharging efficiency, respectively. , , These are the charge / discharge efficiency control coefficients, respectively.

[0084] S33, if If the reactive current reference data is greater than zero, the equivalent cost function of the energy storage battery discharge is selected for minimization to generate the minimum cost and corresponding charge / discharge power data. If the reactive current reference data is greater than zero, the equivalent cost function of the energy storage battery charging is selected for minimization to generate the minimum cost and corresponding charge / discharge power data. When performing the minimization solution, methods such as the golden section method or gradient descent method can be used.

[0085] S4. Based on the inverter design parameter data and the energy storage battery charging and discharging power data, update the active current input to the inverter to generate inverter input analysis data, including the following steps:

[0086] S41. Based on the minimum cost and the corresponding charge / discharge power data, update the inverter's input power to generate the inverter's updated input power. For example, taking a photovoltaic grid-connected inverter as an example. This means that the photovoltaic input power of the inverter is adjusted only when the energy storage battery is discharging;

[0087] S42. Collect and combine the charge and discharge power data and inverter input update power from the minimum cost and corresponding charge and discharge power data to generate inverter input power analysis data.

[0088] S5. Based on the voltage outer loop data, current inner loop data, inverter design parameter data, and energy storage battery charging and discharging power data, perform three-phase modulation voltage data analysis and processing to generate three-phase modulation voltage analysis data, including the following steps:

[0089] S51. Based on voltage outer loop data, current inner loop data, and inverter design parameter data, perform three-phase modulation voltage data analysis and processing to maintain the stability of the low-voltage grid voltage, and generate initial three-phase modulation voltage analysis data. Specifically, this includes the following steps: Based on the collected three-phase output current and real-time phase angle, convert them into components in the rotating coordinate system, namely d-axis current and q-axis current, through Clark transformation and Park transformation. Based on the d-axis current, q-axis current, active current reference value, and calculated reactive current reference data, calculate the current deviation of the d-axis and q-axis, respectively, and input them into the current inner loop PI controller to obtain the voltage command components in the rotating coordinate system, namely d-axis reference voltage and q-axis reference voltage. Dynamic performance and anti-disturbance capability can be improved by adding feedforward decoupling terms and grid voltage feedforward. Then, transform the d-axis reference voltage and q-axis reference voltage into three-phase stationary coordinate system reference voltage through Park transformation and Clark transformation. Generate three-phase modulation voltage analysis data based on SPWM (sinusoidal pulse width modulation) and SVPWM (space vector pulse width modulation) combined with DC bus voltage.

[0090] S52. Based on the DC bus equivalent impedance, DC bus standard voltage, minimum cost, and corresponding charge / discharge power data, the initial three-phase modulation voltage analysis data is adjusted to generate three-phase modulation voltage analysis data. How to adjust the inverter's three-phase modulation voltage based on the energy storage battery's charge / discharge power is common knowledge to those skilled in the art, and it is directly applied here without modification. Therefore, it will not be described in detail in this technical solution, and it will not cause any trouble to those skilled in the art.

[0091] S6. Construct voltage over-limit management data, and perform grid voltage over-limit management operations based on the voltage over-limit management data, including the following steps:

[0092] S61. Collect and combine energy storage battery charging and discharging power data, inverter input analysis data and three-phase modulation voltage analysis data to generate management data for managing voltage over-limit;

[0093] S62. Based on the voltage over-limit management data and inverter input analysis data, manage the charging and discharging of the energy storage battery and the active power input of the inverter respectively, and manage the modulation voltage output of the inverter based on the three-phase modulation voltage analysis data.

[0094] Please refer to Figure 2 A device for controlling voltage overruns in low-voltage distribution networks, comprising an interface, a storage unit, a processor, and a controller;

[0095] The interface is used to input the collected voltage outer loop data, current inner loop data, inverter design parameter data, energy storage battery data, DC bus equivalent impedance and DC bus standard voltage into the storage device.

[0096] Storage is also used to store computer programs;

[0097] The processor is used to execute computer programs to implement a strategy for managing voltage overruns in low-voltage distribution networks;

[0098] The controller is used to perform grid voltage over-limit management operations based on the voltage over-limit management data.

[0099] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A strategy for governing low-voltage distribution network voltage out-of-limit, characterized in that: Comprise the following steps: S1, collect voltage outer loop data, current inner loop data, inverter design parameter data, energy storage battery data; S2, based on the voltage outer loop data, current inner loop data and inverter design parameter data, calculate the reactive current reference data, the inverter target output total current when the inverter outputs the reactive current reference data and the inverter target output ac voltage amplitude data; S3, based on the voltage outer loop data, current inner loop data and inverter design parameter data, the reactive power compensation demand of maintaining low voltage grid voltage stability is calculated; Based on the reactive power gap and the energy storage battery data, the minimum energy storage battery action equivalent cost analysis processing is carried out to meet the reactive power compensation demand of maintaining low voltage grid voltage stability, and the energy storage battery charging and discharging power data is generated; The S3 comprises the following steps: S31, based on the current inner loop data, the inverter design parameter data and the reactive current reference data, calculate the reactive current gap, generate reactive current gap data ; S32, based on the energy storage battery data, reactive current gap data and current price data, an energy storage battery action equivalent cost function is constructed to meet the reactive power compensation demand of maintaining low voltage grid voltage stability, comprising the following formula: Energy storage battery discharge equivalent cost function: ， Energy storage battery charging equivalent cost function: ， Constraint condition: ， wherein, is the electricity consumption cost coefficient (yuan / kW), is the battery aging cost coefficient (yuan / kWh), is the SOC offset penalty coefficient (yuan / ), , is the grid regulation penalty coefficient (yuan / ), , is the energy storage battery charge and discharge power, and are the discharge efficiency and the charge efficiency, respectively, and represent the minimum charge and discharge power of the energy storage battery and the maximum charge and discharge power of the energy storage battery, respectively, and represent the minimum value of the SOC of the energy storage battery and the maximum value of the SOC of the energy storage battery, respectively, is the control period, is the maximum SOC change rate; S33, if the If the reactive current reference data is greater than zero, the energy storage battery charging equivalent cost function is selected to be minimized to generate the minimum cost and corresponding charge and discharge power data. S4, based on the inverter design parameter data and energy storage battery charging and discharging power data, the active current input of the inverter is updated to generate inverter input analysis data; S5, based on the voltage outer loop data, current inner loop data, inverter design parameter data and energy storage battery charging and discharging power data, the three-phase modulation voltage data analysis processing of inverter maintaining low voltage grid voltage stability is carried out, and three-phase modulation voltage analysis data is generated; S6, construct governance voltage out-of-limit management data, and execute grid voltage out-of-limit management operation according to the governance voltage out-of-limit management data. 2.The strategy for treating low-voltage distribution network voltage out-of-limit according to claim 1, characterized in that: The S2 comprises the following steps: S21, based on the voltage outer loop data, the reactive current reference value calculation processing is carried out, and the reactive current reference data is generated; S22, based on the current inner loop data and the reactive current reference data, the inverter target output total current when the inverter outputs the reactive current reference data is calculated; S23, based on the voltage outer loop data, the reactive current reference data and the inverter design parameter data, the inverter target output ac voltage amplitude data when the inverter outputs the reactive current reference data is calculated; S24, judge whether the inverter target output total current is less than or equal to the set rated peak current, and whether the inverter target output ac voltage amplitude data is less than or equal to the set ac voltage amplitude upper limit; S25, if both are, the inverter meets the reactive power compensation demand of maintaining low voltage grid voltage stability, and the energy storage battery does not need to be discharged, otherwise, it does not meet the demand and needs to be discharged. 3.The strategy for treating low-voltage distribution network voltage out-of-limit according to claim 1, characterized in that: The method further comprises updating the S32 , , , and comprises the steps of: Collecting cumulative charge and discharge amount of the energy storage battery and real-time electricity price ; Based on the formula updating the initial power consumption cost coefficient (yuan / kW) according to the initial power consumption cost coefficient (yuan / kW) and the initial power consumption cost coefficient (yuan / kW) of the previous period. is the initial power consumption cost coefficient (yuan / kW);​ Based on the formula updating the initial battery aging cost coefficient (yuan / kWh) and the energy storage battery aging coefficient (% / kWh) according to the formula based on the formula updating the updating, a penalty coefficient for initial grid regulation (kWh / mA), a voltage deviation growth coefficient, a DC bus voltage, a DC bus standard voltage;​ are updated based on the formulas and respectively, where and represent the initial charging efficiency and the initial discharging efficiency respectively, , , , , are the charge-discharge efficiency control coefficients respectively.

4. The strategy for governing low-voltage distribution network voltage out-of-limit according to claim 1, characterized in that: The S4 comprises the following steps: S41, based on the minimum cost and the charging and discharging power data in the corresponding charging and discharging power data, the input power of the inverter is updated to generate inverter input update power; S42, collect, combine the minimum cost and the charging and discharging power data in the corresponding charging and discharging power data and inverter input update power to generate inverter input power analysis data.

5. The strategy for governing the low-voltage distribution network voltage out-of-limit according to claim 1, characterized in that: The S5 comprises the following steps: S51, based on the voltage outer loop data, current inner loop data and inverter design parameter data, perform analysis and processing on three-phase modulation voltage data of the inverter maintaining low-voltage power grid voltage stability, and generate initial three-phase modulation voltage analysis data; S52, based on the DC bus equivalent impedance, DC bus standard voltage and the minimum cost and corresponding charge and discharge power data, adjust the initial three-phase modulation voltage analysis data to generate three-phase modulation voltage analysis data.

6. The strategy for governing low-voltage distribution network voltage out-of-limit according to claim 1, characterized in that: The S6 comprises the following steps: S61, collect and combine the energy storage battery charge and discharge power data, inverter input analysis data and three-phase modulation voltage analysis data to generate voltage out-of-limit management data; S62, manage the charge and discharge of the energy storage battery and the active input of the inverter according to the inverter input analysis data in the voltage out-of-limit management data, and manage the modulation voltage output by the inverter according to the three-phase modulation voltage analysis data.

7. A device for governing low-voltage distribution network voltage excursion, configured to implement the strategy for governing low-voltage distribution network voltage excursion according to any one of claims 1-6, characterized in that: It comprises an interface, a storage, a processor and a controller. The interface is used to input the collected voltage outer loop data, current inner loop data, inverter design parameter data, energy storage battery data, DC bus equivalent impedance and DC bus standard voltage into the storage. The storage is also used to store a computer program. The processor is used to execute the computer program to realize the strategy for managing low-voltage distribution network voltage out-of-limit according to any one of claims 1-6. The controller is used to perform power grid voltage out-of-limit management operation according to the voltage out-of-limit management data.

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