Calculation Method for Absorbable Capacity of Distribution Network Distributed Photovoltaic and Energy Storage Optimization Configuration

Abstract

The present invention relates to a method for calculating the consumable capacity of distributed photovoltaic power in a distribution network and optimizing the energy storage configuration, which includes the following steps: obtaining the annual load electricity consumption and distributed photovoltaic power output data of each basic power supply area, including high-voltage substations, medium-voltage feeders, and low-voltage distribution areas; determining the photovoltaic accessible capacity of high-voltage substations, the photovoltaic accessible capacity of feeders connected to substations, and the photovoltaic accessible capacity of low-voltage distribution areas connected to feeders according to the obtained data; obtaining the energy storage configuration capacity of the basic power supply area; The method for calculating the consumable capacity of distributed photovoltaic power in a distribution network and optimizing the energy storage configuration of the present invention can better study the distributed photovoltaic power consumption level of the distribution network.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage optimization, and particularly relates to a method for calculating the absorbable capacity of distributed photovoltaic power in a distribution network and optimizing the configuration of energy storage. Background Technique

[0002] The large-scale access of distributed photovoltaic power will cause changes in power generation and load balance, affecting the power quality, short-circuit current, power flow distribution and power supply safety of the distribution network. Therefore, it is urgent to evaluate and calculate the maximum access capacity of distributed photovoltaic power, provide relevant basis for the access of distributed photovoltaic power to the distribution network, and realize the safe and orderly access of distributed photovoltaic power to the distribution network.

[0003] At present, in the field of analysis of the accessible capacity of distributed photovoltaic power, the country has a certain research foundation. However, distributed photovoltaic power is mainly configured on the medium and low voltage distribution network side, where the network structure is complex, the parameter loss problem is serious, and the observability and measurability are poor. Therefore, in the previous calculation methods of the accessible capacity of distributed photovoltaic power, by constructing a mathematical model for the calculation and analysis of the accessible capacity, the actual operability is relatively poor.

[0004] To provide a basis for the access planning of distributed photovoltaic power sources, study the principle of the access capacity of distributed photovoltaic power that can meet local and nearby consumption. At the same time, for the convenience of operation, integrating typical experience, linking the access capacity with the load; revealing the relationship between the photovoltaic capacity and the typical load, and obtaining the accessible capacity of distributed photovoltaic power for substations, feeders and low-voltage areas from top to bottom, which has high engineering practice value. Summary of the Invention

[0005] The purpose of the present invention is to provide a practical method for calculating the absorbable capacity of distributed photovoltaic power in a distribution network and optimizing the configuration of energy storage, so as to solve the problems of complex calculation and poor practicability of the traditional method for planning the accessible capacity of distributed photovoltaic power, and further guide the distributed photovoltaic construction work of front-line power workers.

[0006] The present invention solves its technical problems by adopting the following technical solutions:

[0007] A method for calculating the absorbable capacity of distributed photovoltaic power in a distribution network and optimizing the configuration of energy storage includes the following steps:

[0008] Obtain the annual load electricity consumption and distributed photovoltaic power generation data of each basic power supply area, including high-voltage substations, medium-voltage feeders and low-voltage areas;

[0009] Determine the accessible capacity of photovoltaic power for high-voltage substations, the accessible capacity of photovoltaic power for the feeders connected to the substations, and the accessible capacity of photovoltaic power for the low-voltage areas connected to the feeders according to the obtained data;

[0010] Obtain the energy storage configuration capacity of the basic power supply area;

[0011] Among them, the method for obtaining the energy storage configuration capacity of the basic power supply area includes the following steps:

[0012] Determine that the maximum access capacity that can be fully absorbed by the photovoltaic is P pv,max , and then increase the photovoltaic capacity by a ratio of r. Given the historical photovoltaic characteristic curve of the basic power supply area, the charging power and charging time of the energy storage are determined as follows:

[0013] a) Obtain the photovoltaic absorption intensity

[0014] Obtain the photovoltaic absorption intensity coefficient of each basic power supply area after the increase in photovoltaic capacity, and count all the moments when the photovoltaic absorption intensity is greater than 1, that is, the moments when the load electricity consumption cannot absorb the photovoltaic output, to obtain the time set T α ;

[0015] b) Obtain the charging power

[0016] After the increase in photovoltaic capacity, the charging power of the energy storage at all moments when the photovoltaic absorption intensity coefficient is greater than 1 is the difference between the increased photovoltaic output and the original photovoltaic output:

[0017]

[0018] Among them, P ess,t is the photovoltaic output that cannot be absorbed by each basic power supply area at time t, that is, the charging power of the energy storage at time t; is the photovoltaic output of each basic power supply area at time t after the increase in photovoltaic capacity, and P pv,t is the maximum photovoltaic output that can be absorbed by each basic power supply area at time t; the difference between the increased photovoltaic capacity and the photovoltaic power under the original maximum absorption is the power that needs to be stored by the energy storage.

[0019] Among them, the relationship μ between the maximum charging power of the energy storage and the photovoltaic capacity can be expressed as:

[0020]

[0021] Among them, is the moment when the maximum charging power of the energy storage is located;

[0022] According to the photovoltaic characteristic curve, the photovoltaic output at time t max is set to d times the photovoltaic capacity, and then Equation (6) can be rewritten as:

[0023]

[0024] Equation (7) can finally be abbreviated as:

[0025]

[0026] Therefore, it can be concluded that the proportionality coefficient of the charging power of energy storage to the PV capacity is only related to the increasing ratio of the PV capacity.

[0027] Finally, the maximum charging power of energy storage can be expressed as:

[0028] P ess,t =P pv,max ×r×μ (9)

[0029] c) Charging time

[0030] After calculating the charging power of energy storage according to Equation (5), the moment when P ess,t >0 is the moment when energy storage needs to be charged; the continuous charging moments are counted, which is the charging time of energy storage, and can be expressed as:

[0031] T ess,max =max{T 1,ess ,T 2,ess ,...,T m,ess} (10)

[0032] where T m,ess is the continuous charging time of energy storage on the m-th day in historical data.

[0033] Furthermore, the determination principle of the accessible PV capacity in the basic power supply area is as follows:

[0034] Obtain the PV accommodation intensity coefficient α t at each moment in the basic power supply area. When increasing the PV capacity, α t at each moment increases proportionally until α max =1, which can ensure that the PV output at all moments is not greater than the load demand, that is, the PV output can be fully accommodated. That is, the PV output at time t max is equal to the load demand at this time, which can ensure the maximum accessible PV capacity and meet the local and nearby accommodation.

[0035] Furthermore, the method for determining the accessible PV capacity of the high-voltage substation is as follows:

[0036] Obtain the PV accommodation intensity coefficient of the high-voltage substation Determine that the moment with the maximum accommodation intensity coefficient of the 110 kV substation is t max , then the maximum accessible capacity of distributed PV in this substation can be expressed as:

[0037]

[0038] where is the load power demand of the substation at time t max , is the load power demand of the substation at time t maxPhotovoltaic output power of the substation at a certain moment Is the currently connected photovoltaic capacity of the substation

[0039] Furthermore, the method for determining the photovoltaic connectable capacity of the feeder connected to the substation is as follows:

[0040] a) To ensure that the sum of the photovoltaic connectable capacities of all feeders is less than or equal to the photovoltaic consumable capacity of the substation, the photovoltaic connectable capacity of each feeder is proportionally allocated according to its load power consumption at the typical moment, expressed as:

[0041]

[0042] b) If the resource endowment of feeder n - 1 does not support the connection of photovoltaic, its connectable capacity can be evenly distributed to adjacent feeders, and the power generated by the photovoltaic can be transmitted through the bus to achieve photovoltaic consumption.

[0043] Furthermore, the method for determining the photovoltaic connectable capacity of the low - voltage area connected to the feeder is as follows:

[0044] According to the annual load of this area and the distributed photovoltaic characteristic curve, obtain the photovoltaic consumption intensity coefficient, and determine that the moment with the maximum consumption intensity coefficient of the low - voltage area is Then the maximum connectable capacity of the distributed photovoltaic in this low - voltage area can be expressed as:

[0045]

[0046] Wherein, Is The load power consumption demand of the area at the moment Is The photovoltaic output power of the area at the moment Is the currently connected photovoltaic capacity of the area

[0047] The advantages and positive effects of the present invention are:

[0048] The method for measuring the connectable capacity of distributed photovoltaic in the distribution network and optimizing the energy storage configuration of the present invention can better study the distributed photovoltaic consumption level of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. However, it should be noted that these drawings are only designed for explanatory purposes and therefore do not limit the scope of the present invention. In addition, unless otherwise specified, these drawings are only intended to conceptually illustrate the structural configuration described herein and are not necessarily drawn to scale.

[0050] Figure 1Schematic flow chart of the method for calculating the consumable capacity of distributed PV in the distribution network and optimizing the energy storage configuration provided by the embodiments of the present invention; Detailed implementation manners

[0051] First of all, it should be noted that the specific structure, features, advantages, etc. of the present invention will be specifically described by way of examples below. However, all the descriptions are only for the purpose of explanation and should not be construed as any limitation to the present invention. In addition, any single technical feature described or implied in the embodiments mentioned in this article, or any single technical feature shown or implied in the respective drawings, can still be arbitrarily combined or deleted between these technical features (or their equivalents), so as to obtain more other embodiments of the present invention that may not be directly mentioned in this article. In addition, for the sake of simplifying the drawings, the same or similar technical features may be marked only at one place in the same drawing.

[0052] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0053] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0054] As Figure 1 shown, the method for calculating the consumable capacity of distributed PV in the distribution network and optimizing the energy storage configuration provided in this embodiment includes the following steps:

[0055] Obtain the annual load electricity consumption and distributed PV output data of each basic power supply area, including high-voltage substations, medium-voltage feeders, and low-voltage distribution areas;

[0056] Determine the PV accessible capacity of the high-voltage substation, the PV accessible capacity of the feeder connected to the substation, and the PV accessible capacity of the low-voltage distribution area connected to the feeder according to the obtained data;

[0057] Obtain the energy storage configuration capacity of the basic power supply area;

[0058] Among them, the method for obtaining the energy storage configuration capacity of the basic power supply area includes the following steps:

[0059] Determine that the maximum accessible capacity for full PV consumption is P pv,max, then increase the photovoltaic capacity according to the ratio of r. Given the historical photovoltaic characteristic curve of the known basic power supply area, the determination methods of the charging power and charging time of the energy storage are as follows:

[0060] a) Obtain the photovoltaic accommodation intensity

[0061] Obtain the photovoltaic accommodation intensity coefficient of each basic power supply area after the increase of photovoltaic capacity, and count all the moments when the photovoltaic accommodation intensity is greater than 1, that is, the moments when the load electricity consumption cannot accommodate the photovoltaic output, to obtain the time set T α ;

[0062] b) Obtain the charging power

[0063] After the increase of photovoltaic capacity, the charging power of the energy storage at all moments when the photovoltaic accommodation intensity coefficient is greater than 1 is the difference between the increased photovoltaic output and the original photovoltaic output:

[0064]

[0065] where P ess,t is the photovoltaic output that cannot be accommodated in each basic power supply area at time t, that is, the charging power of the energy storage at time t; is the photovoltaic output of each basic power supply area at time t after the increase of photovoltaic capacity, and P pv,t is the maximum photovoltaic output that can be accommodated in each basic power supply area at time t; the difference between the increased photovoltaic capacity and the photovoltaic power under the original maximum accommodation is the power that needs to be stored in the energy storage.

[0066] The relationship μ between the maximum charging power of the energy storage and the photovoltaic capacity can be expressed as:

[0067]

[0068] where is the moment when the maximum charging power of the energy storage is located;

[0069] According to the photovoltaic characteristic curve, the photovoltaic output at time t max is set to d times the photovoltaic capacity, and then Equation (6) can be rewritten as:

[0070]

[0071] Equation (7) can finally be simplified to:

[0072]

[0073] Therefore, it can be concluded that the proportional coefficient of the charging power of the energy storage to the photovoltaic capacity is only related to the increase ratio of the photovoltaic capacity.

[0074] Finally, the maximum charging power of the energy storage can be expressed as:

[0075] P ess,t = P pv,max × r × μ (9)

[0076] c) Charging time

[0077] After calculating the energy storage charging power according to Equation (5), when P ess,t > 0, it is the moment when the energy storage needs to be charged; counting the consecutive charging moments is the energy storage charging time, which can be expressed as:

[0078] T ess,max = max{T 1,ess , T 2,ess ,..., T m,ess} (10)

[0079] where T m,ess is the consecutive charging time of the energy storage on the m-th day in the historical data.

[0080] Specifically, the determination principle of the photovoltaic accessible capacity in the basic power supply area is as follows:

[0081] Obtain the photovoltaic consumption intensity coefficient α at each moment in the basic power supply area t . When increasing the photovoltaic capacity, α at each moment t increases proportionally until α max = 1, which can ensure that the photovoltaic output at all moments is not greater than the load demand, that is, the photovoltaic output can be fully consumed. That is, the photovoltaic output at time t max is equal to the load demand at this time, which can ensure the maximum access of the photovoltaic capacity and meet the local and nearby consumption.

[0082] Specifically, the method for determining the photovoltaic accessible capacity of the high-voltage substation is as follows:

[0083] Obtain the photovoltaic consumption intensity coefficient of the high-voltage substation Determine that the moment with the maximum consumption intensity coefficient of the 110 kV substation is t max . Then, the maximum access capacity of the distributed photovoltaic in this substation can be expressed as:

[0084]

[0085] where is the load power demand of the substation at time t max , is the photovoltaic output power of the substation at time t max , is the current photovoltaic access capacity of the substation.

[0086] Furthermore, the method for determining the photovoltaic accessible capacity of the feeder connected to the substation is as follows:

[0087] a) To ensure that the sum of the PV access capacities of all feeders is less than or equal to the PV accommodation capacity of the substation, the PV access capacity of each feeder is proportionally allocated according to its load power consumption at typical times, which is expressed as:

[0088]

[0089] b) If the resource endowment of feeder n - 1 does not support the access of PV, its access capacity can be evenly distributed to adjacent feeders, and the power generated by the PV can be transmitted through the bus to achieve PV accommodation.

[0090] Specifically, the method for determining the PV access capacity of the low - voltage distribution area connected to the feeder is as follows:

[0091] According to the annual load of this area and the distributed PV characteristic curve, obtain the PV accommodation intensity coefficient, and determine the moment with the maximum accommodation intensity coefficient of the low - voltage distribution area as Then the maximum access capacity of the distributed PV in this low - voltage distribution area can be expressed as:

[0092]

[0093] Among them, is the load power consumption demand of the distribution area at the is the PV output power of the distribution area at the is the current PV access capacity of the distribution area.

[0094] It should be noted that the present invention provides a method for calculating the access capacity of distributed PV in the distribution network from top to bottom (from the high - voltage - level power supply area to the low - voltage power supply area). In order to characterize the accommodation capacity of distributed PV by the loads in each basic power supply area of the high - voltage substation, medium - voltage feeder and low - voltage distribution area, a PV accommodation intensity index is constructed. This index is the ratio of the actual output power of distributed PV in a certain power supply area and at a certain voltage level of the power grid to the corresponding load power consumption, and can be expressed as:

[0095]

[0096] Among them, P pv,t is the power generated by distributed PV at time t, and P load,t is the load power consumption at time t.

[0097] The evaluation principle of distributed PV accommodation based on the PV accommodation intensity index is as follows:

[0098] If, within a certain period of time, α max = max(α t) If < 1, it indicates that on the premise that the peak shaving capacity of the large power grid meets the requirements, the instantaneous power generated by distributed photovoltaics can be consumed within the access area and the required voltage level range, and there is still room for more photovoltaics to be connected to the system.

[0099] The above embodiments have described the present invention in detail, but the content described is only the preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A method for calculating the absorbable capacity of distributed photovoltaic power in the distribution network and optimizing the energy storage configuration, characterized in that, It includes the following steps: Obtain the annual load electricity consumption and distributed photovoltaic output data of each basic power supply area, including high-voltage substations, medium-voltage feeders, and low-voltage distribution areas; Determine the photovoltaic accessible capacity of the high-voltage substation, the photovoltaic accessible capacity of the feeder connected to the substation, and the photovoltaic accessible capacity of the low-voltage distribution area connected to the feeder according to the obtained data; Obtain the energy storage configuration capacity of the basic power supply area; Among them, the method for obtaining the energy storage configuration capacity of the basic power supply area includes the following steps: Determine that the maximum access capacity for full accommodation of photovoltaic power is P pv,max , and then increase the photovoltaic capacity in proportion to r. Given the historical photovoltaic characteristic curve of the basic power supply area, the determination methods for the charging power and charging time of energy storage are as follows: a) Obtain the photovoltaic accommodation intensity Obtain the PV accommodation intensity coefficients of each basic power supply area after the PV capacity increase, and count all the moments when the PV accommodation intensity is greater than 1, that is, the moments when the load electricity consumption cannot accommodate the PV output, to obtain the time set T α ; b) Obtain the charging power After the photovoltaic capacity increases, the charging power of the energy storage at all times when the photovoltaic accommodation intensity coefficient is greater than 1 is the difference between the increased photovoltaic output and the original photovoltaic output: Among them, P ess,t is the PV output that cannot be absorbed by each basic power supply area at time t, that is, the charging power of the energy storage at time t; is the PV output of each basic power supply area at time t after the PV capacity increases, and P pv,t is the maximum PV output that can be absorbed by each basic power supply area at time t; the difference between the PV power under the condition of increased PV capacity and the original maximum absorption is the power that needs to be stored by the energy storage; Among them, the relationship μ between the maximum charging power of the energy storage and the photovoltaic capacity can be expressed as: Among them, is the moment when the maximum charging power of the energy storage occurs; According to the photovoltaic characteristic curve, the photovoltaic output at time t max is set to d times the photovoltaic capacity. Furthermore, Equation (6) can be rewritten as: Equation (7) can finally be abbreviated as: Finally, the maximum charging power of the energy storage can be expressed as: P ess,t = P pv,max × r × μ (9) c) Charging time After calculating the energy storage charging power according to Equation (5), when P ess,t > 0, it is the time when the energy storage needs to be charged; counting the continuous charging time is the energy storage charging time, which can be expressed as: T ess,max = max{T 1,ess , T 2,ess ,..., T m,ess} (10) Among them, T m,ess is the continuous charging time of the energy storage on the m-th day in historical data.

2. The method for calculating the absorbable capacity of distributed PV in the distribution network and optimizing the energy storage configuration according to claim 1, wherein: The determination principle of the photovoltaic accessible capacity of the basic power supply area is: Obtain the PV accommodation intensity coefficient α at each moment in the basic power supply area t , when increasing the PV capacity, α at each moment t increases proportionally until α max = 1, which can ensure that the PV output at all moments is not greater than the load demand, that is, the PV output can be fully accommodated, that is, at time t max the PV output at the moment is equal to the load demand at this time, which can ensure the maximum access of the PV capacity and meet the local and nearby accommodation.

3. The method for measuring the accessible capacity of distributed photovoltaic power in the distribution network and optimizing the energy storage configuration according to claim 1, characterized in that: The method for determining the photovoltaic accessible capacity of the high-voltage substation is: Obtain the photovoltaic accommodation intensity coefficient of the high-voltage substation Determine that the moment with the maximum accommodation intensity coefficient of the 110 kV substation is t max , then the maximum access capacity of the distributed photovoltaic in this substation can be expressed as: Among them, is the load power demand of the substation at time t, max and is the PV output power of the substation at time t, max and is the currently connected PV capacity of the substation.

4. The method for measuring the accessible capacity of distributed photovoltaic power in the distribution network and optimizing the energy storage configuration according to claim 3, characterized in that: The method for determining the photovoltaic accessible capacity of the feeder connected to the substation is: a) To ensure that the sum of the photovoltaic access capacities of all feeders is less than or equal to the photovoltaic accessible capacity of the substation, the photovoltaic accessible capacity of each feeder is proportionally allocated according to its load electricity consumption at typical times, expressed as: b) If the resource endowment of feeder n-1 does not support the access of photovoltaic power, the access capacity can be evenly distributed to adjacent feeders, and the power generated by the photovoltaic can be transmitted through the bus to achieve the consumption of photovoltaic power.

5. The method for measuring the accessible capacity of distributed photovoltaic power in the distribution network and optimizing the energy storage configuration according to claim 4, characterized in that: The method for determining the photovoltaic accessible capacity of the low-voltage distribution area connected to the feeder is: According to the annual load and distributed photovoltaic characteristic curve of this low-voltage power distribution area, the photovoltaic accommodation intensity coefficient is obtained, and the moment with the maximum accommodation intensity coefficient of the low-voltage power distribution area is determined as Then the maximum access capacity of the distributed photovoltaic in this low-voltage power distribution area can be expressed as: Among them, is the power consumption demand of the substation area load at time is the PV output power of the substation area at time is the currently connected PV capacity of the substation area.

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