Method and device for improving bearing capacity of power grid based on roof photovoltaic regulation and control

Abstract

The invention relates to a power grid bearing capacity improving method and device based on roof photovoltaic regulation, and the method comprises the steps: deploying a battery energy storage system at a voltage sensitive node, and planning the capacity of the battery energy storage system; controlling a roof photovoltaic unit to dynamically adjust reactive power and active power by adopting a hybrid control strategy of volt-watt control and volt-safety control; and when the roof photovoltaic unit adopts volt-watt control, activating the battery energy storage system, and absorbing excess energy generated by photovoltaic active power reduction through the battery energy storage system. The bearing capacity hosting capability of the low-voltage power grid can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of low-voltage power distribution networks, in particular to a method and device for improving power grid carrying capacity based on roof photovoltaic regulation. BACKGROUND

[0002] With the acceleration of global energy transformation, the penetration rate of distributed photovoltaics in low-voltage distribution networks continues to rise, and the overvoltage problem caused thereby has become a key bottleneck restricting the carrying capacity of the power grid. Traditional voltage regulation schemes mainly rely on the autonomous control function of photovoltaic inverters: Volt-Var (V-V) control adjusts the reactive power dynamically to support voltage, but in low X / R power grids, a large amount of reactive current needs to be injected, resulting in a sharp increase in line loss and the risk of equipment overload; Volt-Watt (V-W) control directly reduces photovoltaic active power output, which can quickly suppress overvoltage, but causes 5%-15% annual energy waste and damages investor returns. Existing research shows that a single control strategy can only improve the power grid carrying capacity (HC) by 1.5-2 times, and the hard power limit of V-W control can lead to the "rush to generate effect" - photovoltaics far from the point of common coupling (PCC) will reduce the capacity first due to higher voltage sensitivity, exacerbating system unfairness. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a method and device for improving the carrying capacity of a power grid based on roof photovoltaic regulation, which can improve the carrying capacity of a low-voltage power grid.

[0004] The technical solution adopted by the present application to solve the technical problem is to provide a method for improving the carrying capacity of a power grid based on roof photovoltaic regulation, comprising the following steps:

[0005] Deploying a battery energy storage system at a voltage-sensitive node and planning the capacity of the battery energy storage system;

[0006] Controlling the roof photovoltaic unit to adopt a hybrid control strategy of V-W control and V-A control to dynamically adjust reactive and active power;

[0007] When the roof photovoltaic unit adopts V-W control, activating the battery energy storage system to absorb excess energy generated by photovoltaic active power reduction through the battery energy storage system.

[0008] When planning the capacity of the battery energy storage system, the power capacity of the battery energy storage system is determined by BESS MaxPower = max{PV curtailed [n]}, wherein BESS MaxPower is the maximum power requirement of the battery energy storage system, PV curtailed[n] is the cut power value of the nth roof photovoltaic unit when the voltage-watt control is adopted.

[0009] When the capacity of the battery energy storage system is planned, the energy capacity of the battery energy storage system is determined by , wherein the BESS Capacity is the energy capacity of the battery energy storage system, the ∑P curtailed (n)·Duration is the all-day theoretical energy storage demand of the battery energy storage system, the P curtailed (n) is the maximum cut power of the nth roof photovoltaic unit under voltage-watt control, the Duration is the time interval, the DoD is the depth of discharge of the battery energy storage system, and the Eff is the charge-discharge efficiency of the battery energy storage system.

[0010] When the roof photovoltaic unit adopts the mixed control strategy of voltage-watt control and voltage-ampere control to dynamically adjust reactive power and active power, when the roof photovoltaic unit adopts voltage-ampere control, the roof photovoltaic unit maintains the grid voltage within the allowable range by adjusting the reactive power output of the roof photovoltaic unit; when the roof photovoltaic unit adopts voltage-watt control, the roof photovoltaic unit reduces the active power by a preset proportion or directly reduces the active power to zero output.

[0011] When the roof photovoltaic unit adopts voltage-ampere control, the limit value of the reactive power injected by the roof photovoltaic unit into the grid is determined by , wherein the Q pv,n is the limit value of the reactive power injected by the nth roof photovoltaic unit into the grid, the S pv,n is the rated apparent power of the nth roof photovoltaic unit, and the P pv,n is the active power of the nth roof photovoltaic unit.

[0012] The method for improving the carrying capacity of the grid based on roof photovoltaic regulation further comprises: evaluating the carrying capacity of the grid, and the performance of the grid is quantified by the charge-discharge rate, the battery-photovoltaic power ratio, the carrying capacity coefficient, and the photovoltaic-load energy ratio during the evaluation.

[0013] When the carrying capacity of the grid is evaluated, the charge-discharge rate is calculated by , the battery-photovoltaic power ratio is calculated by , the carrying capacity coefficient is calculated by , and the photovoltaic-load energy ratio is calculated by , wherein the E-rate is the charge-discharge rate, the BESS MarPower is the maximum power demand of the battery energy storage system, the BESS Capacity is the actual capacity of the battery energy storage system taking into account the loss, the BESSPVratio is the battery-photovoltaic power ratio, and the PVPower is the daily total power generation of the rooftop photovoltaic unit, S PV is the daily total power generation of the rooftop photovoltaic unit, S L is the daily total power consumption of the load.

[0014] The technical scheme adopted by the present application to solve its technical problems is: to provide a power grid carrying capacity improvement device based on rooftop photovoltaic regulation, comprising:

[0015] A deployment planning module is configured to deploy a battery energy storage system at a voltage-sensitive node and plan the capacity of the battery energy storage system.

[0016] A control module is configured to control the rooftop photovoltaic unit to adopt a hybrid control strategy of V-W control and V-A control to dynamically adjust reactive power and active power.

[0017] An activation module is configured to activate the battery energy storage system when the rooftop photovoltaic unit adopts V-W control, and to absorb excess energy generated by photovoltaic active power reduction through the battery energy storage system.

[0018] The technical scheme adopted by the present application to solve its technical problems is: to provide an electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the power grid carrying capacity improvement method based on rooftop photovoltaic regulation.

[0019] The technical scheme adopted by the present application to solve its technical problems is: to provide a computer-readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the steps of the power grid carrying capacity improvement method based on rooftop photovoltaic regulation.

[0020] Advantages

[0021] Due to the adoption of the above technical scheme, the present application has the following advantages and positive effects compared with the prior art: by combining the V-V control strategy and the V-W control strategy, the present application reduces line loss caused by reactive current circulation, and combines the battery energy storage system to store reduced energy, thereby improving energy utilization rate and increasing the comprehensive efficiency of the power grid system by 30%-40%. The battery energy storage system is deployed at a voltage-sensitive node to specifically alleviate the overvoltage problem, thereby improving the low-voltage power grid carrying capacity (HC) by more than 30%, and improving the accuracy by 50% compared with the traditional centralized energy storage scheme. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1is a flow chart of a power grid carrying capacity improvement method based on roof photovoltaic regulation according to the first embodiment of the present application;

[0023] Figure 2 is a flow chart of power grid carrying capacity evaluation according to the first embodiment of the present application. DETAILED DESCRIPTION

[0024] The present application will be further described below with reference to specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not used to limit the scope of the present application. Furthermore, it should be understood that those skilled in the art can make various modifications or changes to the present application after reading the content taught by the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0025] The first embodiment of the present application relates to a power grid carrying capacity improvement method based on roof photovoltaic regulation, as shown in Figure 1 comprising the following steps:

[0026] Step 1, deploying a battery energy storage system at a voltage-sensitive node and planning the capacity of the battery energy storage system.

[0027] In this step, the battery energy storage system is deployed at the voltage-sensitive node, and the locally stored voltage watt V control reduction energy is used to absorb the excess energy generated by the photovoltaic active power reduction to achieve optimization. In the present embodiment, the capacity planning mode of the battery energy storage system is as follows:

[0028] For the power capacity of the battery energy storage system, the maximum power demand of the battery energy storage system is the maximum reduction power value of each roof photovoltaic unit under V-W control, that is:

[0029] BESS MaxPower = max{PV curtailed [n]};

[0030] Wherein, BESS MaxPower is the maximum power demand of the battery energy storage system, and PV curtailed [n] is the reduction power value of the nth roof photovoltaic unit under V-W control.

[0031] For the energy capacity of the battery energy storage system, the theoretical energy storage demand of the battery energy storage system throughout the day needs to be quantified, and the discharge depth and charge-discharge efficiency of the battery energy storage system are taken into account. In the present embodiment, the planning mode of the energy capacity of the battery energy storage system is as follows:

[0032]

[0033] Wherein, BESS Capacity is the energy capacity of the battery energy storage system, and ∑P curtailed(n) Duration is the full-day theoretical energy storage demand of the battery energy storage system, P curtailed (n) is the power reduction of the nth photovoltaic unit under voltage-to-watt control, Duration is the time interval, DoD is the depth of discharge of the battery energy storage system, usually 80%, Eff is the charge-discharge efficiency of the battery energy storage system, usually 98%.

[0034] Step 2, when the roof photovoltaic unit adopts a hybrid control strategy of voltage-to-watt control and voltage-to-ampere control, dynamically adjusts the reactive and active power.

[0035] The core goal of voltage-to-ampere control is to maintain the grid voltage within the allowed range by adjusting the reactive power output of the roof photovoltaic unit. When the grid voltage exceeds the upper limit, the system absorbs reactive power (inductive region operation); when the grid voltage is lower than the lower limit, the roof photovoltaic unit injects reactive power into the grid to raise the voltage. When the "watt priority" configuration is adopted within the inverter power limit, the system prioritizes maximizing active power generation, while voltage-to-ampere control requires additional reactive power to support the voltage level. When voltage-to-ampere control is used, the limit of reactive power injected by the roof photovoltaic unit into the grid is determined by the following method:

[0036]

[0037] Where, Q pv,n is the limit of reactive power injected by the nth roof photovoltaic unit into the grid, S pv,n is the rated apparent power of the nth roof photovoltaic unit, P pv,n is the active power of the nth roof photovoltaic unit.

[0038] Voltage-to-watt control is specifically adjusted for the upper voltage limit. When the voltage exceeds the threshold, the roof photovoltaic unit reduces the active power by a preset proportion (soft reduction strategy), or directly reduces the active power to zero output (hard reduction strategy). This strategy is particularly effective in low X / R ratio grids, significantly alleviating the overvoltage problem caused by high penetration of DER. Compared with the hard reduction strategy, the soft reduction strategy can reduce about 5% of annual power generation loss.

[0039] Step 3, when the roof photovoltaic unit adopts voltage-to-watt control, activate the battery energy storage system, and absorb the excess energy generated by photovoltaic active power reduction through the battery energy storage system.

[0040] It is worth mentioning that the present embodiment also evaluates the grid carrying capacity, i.e. by constructing a randomized HC evaluation framework, the relationship between the battery energy storage system capacity demand and the HC gain under different control strategies is quantified. As Figure 2 shown, the evaluation process of the present embodiment includes three stages: initialization configuration, automatic simulation cycle and data analysis output.

[0041] The performance of the power grid is quantified by the charge-discharge rate, the battery-PV power ratio, the hosting capacity coefficient, and the PV-load energy ratio at the time of evaluation.

[0042] The charge-discharge rate is calculated by , where E-rate is the charge-discharge rate, BESS MarPower is the maximum power demand of the battery energy storage system, BESS Capacity is the actual capacity of the battery energy storage system taking into account losses.

[0043] The battery-PV power ratio is calculated by , where BESSPVratio is the battery-PV power ratio, PV Power is the rated power capacity of the rooftop PV unit.

[0044] The hosting capacity coefficient is calculated by , where HCC is the hosting capacity coefficient, Energytobecurtailed is the amount of PV power generation that needs to be curtailed.

[0045] The PV-load energy ratio is calculated by , where PVLoadRatio is the PV-load energy ratio, S PV is the daily total power generation of the rooftop PV unit, S L is the daily total power consumption of the load.

[0046] It can be found that, by combining the V-V control strategy and the V-W control strategy, the present application reduces line losses caused by reactive current flow, and combines the battery energy storage system to store curtailed energy, thereby achieving an increase in energy utilization rate and an increase in the comprehensive efficiency of the power grid system by 30%-40%. The present application deploys the battery energy storage system at a voltage-sensitive node, specifically alleviates the problem of overvoltage, and increases the hosting capacity (HC) of the low-voltage power grid by more than 30%, which is 50% more accurate than the traditional centralized energy storage scheme.

[0047] The second embodiment of the present application relates to a power grid hosting capacity improvement device based on rooftop PV regulation, comprising:

[0048] A deployment planning module is configured to deploy a battery energy storage system at a voltage-sensitive node and plan the capacity of the battery energy storage system.

[0049] A control module is configured to control the rooftop PV unit to adopt a hybrid control strategy of V-W control and V-A control to dynamically adjust reactive and active power.

[0050] An activation module is configured to activate the battery energy storage system to absorb excess energy caused by active power reduction of the rooftop PV unit when the rooftop PV unit adopts V-W control.

[0051] The deployment planning module comprises a power capacity planning unit configured to determine the power capacity of the battery energy storage system by MaxPower = max{PV curtailed [n]} where BESS MaxPower is the maximum power demand of the battery energy storage system, PV curtailed [n] is the reduction power value of the nth rooftop PV unit when adopting V-W control.

[0052] The deployment planning module comprises an energy capacity planning unit configured to determine the energy capacity of the battery energy storage system by where BESS Capacity is the energy capacity of the battery energy storage system, ∑P curtailed (n)·Duration is the theoretical energy storage demand of the battery energy storage system throughout the day, P curtailed (n) is the maximum reduction power of the nth rooftop PV unit when adopting V-W control, Duration is the time interval, DoD is the depth of discharge of the battery energy storage system, and Eff is the charge-discharge efficiency of the battery energy storage system.

[0053] The control module is configured to control the rooftop PV unit to maintain the grid voltage within the allowable range by adjusting the reactive power output of the rooftop PV unit when the rooftop PV unit adopts V-A control, and to control the rooftop PV unit to reduce the active power by a preset proportion or directly reduce the active power to zero output when the rooftop PV unit adopts V-W control.

[0054] The control module is configured to determine the limit of the reactive power injected by the rooftop PV unit into the grid by when the rooftop PV unit adopts V-A control, where Q pv,n is the limit of the reactive power injected by the nth rooftop PV unit into the grid, S pv,n is the rated apparent power of the nth rooftop PV unit, and P pv,n is the active power of the nth rooftop PV unit.

[0055] The rooftop PV-based grid carrying capacity improvement device further comprises an evaluation module configured to evaluate the carrying capacity of the grid by quantifying the performance of the grid through the charge-discharge rate, the battery-PV power ratio, the carrying capacity coefficient, and the PV-load energy ratio.

[0056] The evaluation module comprises:

[0057] a charge-discharge rate calculation unit configured to calculate a charge-discharge rate by

[0058] a battery-photovoltaic power ratio calculation unit configured to calculate a battery-photovoltaic power ratio by

[0059] a hosting capacity coefficient calculation unit configured to calculate a hosting capacity coefficient by

[0060] a photovoltaic-load energy ratio calculation unit configured to calculate a photovoltaic-load energy ratio by

[0061] wherein E-rate is the charge-discharge rate, BESS MarPower is the maximum power demand of the battery energy storage system, BESS Capacity is the actual capacity of the battery energy storage system taking into account losses, BESSPVratio is the battery-photovoltaic power ratio, PV Power is the rated power capacity of the rooftop photovoltaic unit, HCC is the hosting capacity coefficient, Energytobecurtailed is the amount of photovoltaic power generation to be curtailed, PVLoadRatio is the photovoltaic-load energy ratio, S PV is the daily total power generation of the rooftop photovoltaic unit, S L is the daily total power consumption of the load.

[0062] A third embodiment of the present application relates to an electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the method for improving the hosting capacity of a power grid based on rooftop photovoltaic regulation of the first embodiment when executing the computer program.

[0063] A fourth embodiment of the present application relates to a computer-readable storage medium having stored thereon a computer program, the computer program implementing the steps of the method for improving the hosting capacity of a power grid based on rooftop photovoltaic regulation of the first embodiment when executed by a processor.

[0064] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems, or computer program products. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, magnetic disks and optical storage media) embodying computer program code thereon.

[0065] ​​​​The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0066] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0067] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0068] The above description is only specific embodiments of the application, but the protection scope of the application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered by the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A method for improving grid carrying capacity based on rooftop photovoltaic regulation, characterized in that: The following steps are involved: Deploy a battery energy storage system at a voltage-sensitive node and plan the capacity of the battery energy storage system; The rooftop photovoltaic units are controlled using a hybrid control strategy of volt-watt control and volt-ampere control to dynamically adjust reactive and active power; When the rooftop photovoltaic unit adopts volt-watt control, the battery energy storage system is activated to absorb excess energy generated by photovoltaic active power reduction.

2. The method for improving grid carrying capacity based on rooftop photovoltaic regulation according to claim 1 is characterized in that: When planning the capacity of the battery energy storage system, the power capacity of the battery energy storage system is calculated by BESS. MaxPower =max{PV curtailed [n]} is determined, where BESS MaxPower is the maximum power demand of the battery energy storage system, PV curtailed [n] is the power reduction value of the nth rooftop photovoltaic unit under volt-watt control.

3. The method for improving grid carrying capacity based on rooftop photovoltaic regulation according to claim 1 is characterized in that: When planning the capacity of the battery energy storage system, the energy capacity of the battery energy storage system is calculated by Determine, among which BESS Capacity is the energy capacity of the battery energy storage system, ∑P curtailed (n) Duration is the theoretical energy storage requirement of the battery energy storage system throughout the day, P curtailed (n) is the maximum curtailment power of the nth rooftop PV unit under volt-watt control; Duration is the time interval; DoD is the depth of discharge of the battery energy storage system, and Eff is the charge and discharge efficiency of the battery energy storage system.

4. The method for improving grid carrying capacity based on rooftop photovoltaic regulation according to claim 1, characterized in that: When the rooftop photovoltaic unit is controlled by a hybrid control strategy of volt-watt control and volt-ampere control to dynamically adjust reactive and active power, when the rooftop photovoltaic unit adopts volt-ampere control, the grid voltage is maintained within an allowable range by adjusting the reactive output of the rooftop photovoltaic unit; when the rooftop photovoltaic unit adopts volt-watt control, the rooftop photovoltaic unit reduces active power according to a preset ratio or directly reduces the active power to zero output.

5. The method for improving grid carrying capacity based on rooftop photovoltaic regulation according to claim 4 is characterized in that: When the rooftop photovoltaic unit adopts volt-ampere control, the limit of reactive power injected by the rooftop photovoltaic unit into the grid is Determine, where Q pv,n is the limit of reactive power injected into the grid by the nth rooftop photovoltaic unit, S pv,n is the rated apparent power of the nth rooftop photovoltaic unit, P pv,n is the active power of the nth rooftop photovoltaic unit.

6. The method for improving grid carrying capacity based on rooftop photovoltaic regulation according to claim 1 is characterized in that: Also includes: The grid's carrying capacity is assessed, quantifying grid performance through charge and discharge rates, battery-to-PV power ratio, carrying capacity factor, and PV-to-load energy ratio.

7. The method for improving grid carrying capacity based on rooftop photovoltaic regulation according to claim 6 is characterized in that: When evaluating the carrying capacity of the power grid, the charge and discharge rate is The battery-photovoltaic power ratio is calculated by The load capacity coefficient is calculated by The photovoltaic-load energy ratio is calculated by Calculated, where E-rate is the charge and discharge rate, BESS MarPower is the maximum power requirement of the battery energy storage system, BESS Capacity is the actual capacity of the battery energy storage system taking into account losses, BESSPVratio is the battery-photovoltaic power ratio, PV Power is the rated power capacity of the rooftop photovoltaic unit, HCC is the load capacity coefficient, Energytobecurtailed is the photovoltaic power generation that needs to be curtailed, PVLoadRatio is the photovoltaic-load energy ratio, S PV is the total daily power generation of the rooftop photovoltaic unit, S L is the total daily electricity consumption of the load.

8. A device for improving the grid carrying capacity based on rooftop photovoltaic regulation, characterized in that: include: A deployment planning module, configured to deploy the battery energy storage system at voltage-sensitive nodes and plan the capacity of the battery energy storage system; A control module is used to control the rooftop photovoltaic unit to dynamically adjust reactive and active power using a hybrid control strategy of volt-watt control and volt-ampere control; The activation module is used to activate the battery energy storage system when the rooftop photovoltaic unit adopts volt-watt control, so as to absorb the excess energy generated by the photovoltaic active power reduction through the battery energy storage system.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method for improving the grid carrying capacity based on rooftop photovoltaic regulation as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for improving the grid carrying capacity based on rooftop photovoltaic regulation as described in any one of claims 1 to 7 are implemented.

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