A method for controlling power quality in a substation using orderly charging and discharging of distributed energy storage

Abstract

The present invention discloses a method for managing power quality in a substation using distributed energy storage for orderly charging and discharging, and belongs to the technical field of power quality management in a substation. The specific steps of the method are as follows: obtaining substation data, charging pile data, distributed energy storage system data, and distributed photovoltaic power generation system data; constructing a power management strategy optimization model based on distributed energy storage systems and distributed photovoltaic power generation systems; and regulating charging piles according to the output of the power management strategy optimization model. The above-mentioned method for managing power quality in a substation using distributed energy storage for orderly charging and discharging fully considers the combined effects of distributed photovoltaic power generation systems and distributed energy storage systems, is more in line with the actual power grid system, improves the ability to translate photovoltaic output, and provides an effective optimization strategy for power quality management in the substation.

Description

Technical Field

[0001] The present invention relates to the technical field of power quality management in power substations, and in particular to a method for managing power quality in power substations by orderly charging and discharging distributed energy storage. Background Art

[0002] The existing technology focuses on solving the energy storage location and capacity issues of large-scale distributed energy in the grid-connected distribution network. However, with the access of a large number of electric vehicle charging piles and distributed photovoltaics, the power grid has been faced with problems such as heavy load, low voltage and increased network loss. In order to ensure the stability of the power grid and ensure economic benefits, the prior art uses an orderly charging and discharging plan strategy to regulate the charging and discharging state, phase or charging load of the plugged-in charging piles to optimize the power quality of the current period. For example, the patent with announcement number CN113602131 discloses an orderly charging and discharging method for electric vehicles based on optimizing the power quality of the distribution station area. According to the charging pile operation data of the current period, the phase, adjustable charging load and dischargeable power of the plugged-in charging piles are determined; the power quality of the station area is calculated according to the station area data analysis of the current period, and it is determined whether the power quality of the station area meets the preset requirements; according to the power quality of the station area and the charging pile operation data, the orderly charging and discharging plan strategy of the charging pile is periodically generated; when the power quality of the station area does not meet the preset requirements, the charging and discharging state, phase or charging load of the plugged-in charging piles are regulated according to the orderly charging and discharging plan strategy to optimize the power quality of the station area in the current period. By periodically formulating an orderly charging and discharging strategy for electric vehicles for planned charging or discharging, the problems of heavy load, overload and three-phase imbalance in the station area are solved. However, existing technologies do not take into account the situation of distributed energy storage and photovoltaic output. Summary of the invention

[0003] The purpose of the present invention is to provide a method for controlling power quality in an area by orderly charging and discharging distributed energy storage, so as to solve the above-mentioned technical problems.

[0004] To achieve the above objectives, the present invention provides a method for controlling power quality in a substation area by orderly charging and discharging distributed energy storage, and the specific steps are as follows:

[0005] Step S1: Acquire data of the area, charging piles, distributed energy storage system and distributed photovoltaic power generation system;

[0006] Step S2: construct an energy management strategy optimization model based on distributed energy storage system and distributed photovoltaic power generation system;

[0007] Step S3: Regulate the charging pile according to the output of the power management strategy optimization model.

[0008] Preferably, in step S1, the station area data includes load data and voltage data;

[0009] Charging pile data includes charging pile voltage data, load data, electric vehicle charging data and electricity price data;

[0010] Distributed energy storage system data includes energy storage data, maximum energy storage data, and charging and discharging data;

[0011] The distributed photovoltaic power generation system data includes the voltage data and power generation data of the distributed photovoltaic power generation system.

[0012] Preferably, in step S2, the power management strategy optimization model based on the distributed energy storage system and the distributed photovoltaic power generation system is as follows:

[0013] ;

[0014] in, is the comprehensive voltage deviation, is the load improvement degree, and C is the energy storage cost.

[0015] Preferably, the comprehensive voltage deviation calculation formula is as follows:

[0016] ;

[0017] in, is the voltage deviation conversion coefficient, It is the voltage deviation indicator;

[0018] The calculation formula is as follows:

[0019] ;

[0020] in, is the number of nodes, For the Node voltage deviation index, is the phase number, For the cycle;

[0021] ;

[0022] in, For the Nodes Mutually The voltage value at the moment, and are the minimum and maximum values ​​of the total voltage, respectively. is the rated voltage value, and Respectively Nodes The minimum and maximum phase voltages, For the The active power of each node, is the total reactive power.

[0023] Preferably, the load improvement The calculation formula is as follows:

[0024] ;

[0025] in, is the load improvement conversion factor, It is the load improvement index, and the calculation formula is as follows:

[0026] ;

[0027] in, is the average load during the cycle, is the original peak-to-valley difference of the power grid, is the peak-to-valley difference of the composite effect of the distributed photovoltaic power generation system and the distributed energy storage system. The calculation formula is as follows:

[0028] ;

[0029] in, and are the maximum load and minimum load of the distributed photovoltaic power generation system, and are the charging power and discharging power of the energy storage system respectively.

[0030] Preferably, the calculation formula of energy storage cost C is as follows:

[0031] ;

[0032] in, is the fixed investment cost, is the energy storage operating cost, Profit from peak-valley price difference of energy storage;

[0033] Energy storage operating costs Including maintenance costs and cable loss costs, the calculation formula is as follows:

[0034] ;

[0035] in, is the number of energy storage units, is the average maintenance cost of the energy storage unit, For the The rated capacity of each energy storage unit, is the unit line loss cost, is the number of lines, For the Line in The power loss at the moment, is the time interval;

[0036] Energy storage peak-valley price difference income The calculation formula is as follows:

[0037] ;

[0038] in, Set a period for energy storage, Set the cycle interval number for energy storage, Design loss rate for energy storage, is the energy storage utilization rate in the process of electricity price arbitrage, is the total energy storage, and are the electricity prices for charging and discharging energy storage respectively.

[0039] Preferably, the constraint functions of the electric energy management strategy optimization model include a power grid operation constraint function, a three-phase imbalance constraint function, and a distributed energy storage system constraint function.

[0040] Preferably, the power grid operation constraint function is as follows:

[0041] ;

[0042] ;

[0043] ;

[0044] in, , , , as well as They are the active power of generator, distributed photovoltaic system, distributed energy storage system, electric vehicle and load; For the Phase Node exist The voltage amplitude at the moment, For the Phase and Di Phase-to-phase node and nodes The conductance between For the Phase and Di Phase-to-phase node and nodes The electrical susceptance between For the Phase and Di Phase-to-phase node and nodes The voltage phase angle difference between

[0045] , , , as well as They are the reactive power of generator, distributed photovoltaic system, distributed energy storage system, electric vehicle and load.

[0046] Preferably, the three-phase unbalance constraint function is as follows:

[0047] ;

[0048] in, For Node exist The three-phase unbalance coefficient at the moment, It is the maximum three-phase unbalance coefficient that is set.

[0049] Preferably, the distributed energy storage system constraint function calculation formula is as follows:

[0050] ;

[0051] ;

[0052] ;

[0053] ;

[0054] in, For Node In the energy storage cycle Neidi The energy storage power for a time interval, is the energy storage energy at the initial time of the energy storage cycle, is the energy storage energy at the end of the energy storage cycle, for Energy storage at all times, is the maximum value of energy storage, It is the maximum power of energy storage. In one energy storage cycle, the total charge amount is equal to the total discharge amount, the energy capacity remains unchanged, and the energy storage energy and energy storage power are within the set range.

[0055] Therefore, the present invention adopts the above-mentioned method for power quality management in substations using orderly charging and discharging of distributed energy storage, which has the following beneficial effects: the load improvement degree in the power management strategy optimization model based on the distributed energy storage system and the distributed photovoltaic power generation system fully considers the combined effect of the distributed photovoltaic power generation system and the distributed energy storage system, is more in line with the actual power grid system, improves the ability to translate photovoltaic output, and provides an effective optimization strategy for power quality management in substations.

[0056] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a flow chart of a method for managing power quality in a substation using orderly charging and discharging of distributed energy storage according to the present invention;

[0058] Figure 2 It is a peak-to-valley difference diagram of the composite action of the distributed photovoltaic power generation system and the distributed energy storage system of the present invention;

[0059] Figure 3 This is a simulation test result diagram of the present invention. DETAILED DESCRIPTION

[0060] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the invented product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "setting", "installation", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0062] Example 1

[0063] like Figure 1 As shown, a method for controlling power quality in a substation using orderly charging and discharging of distributed energy storage is described, and the specific steps are as follows:

[0064] Step S1: Acquire data on the area, charging piles, distributed energy storage systems, and distributed photovoltaic power generation systems.

[0065] Charging pile data includes charging pile voltage data, load data, electric vehicle charging data and electricity price data.

[0066] Distributed energy storage system data includes energy storage data, maximum energy storage data, and charging and discharging data.

[0067] The distributed photovoltaic power generation system data includes the voltage data and power generation data of the distributed photovoltaic power generation system.

[0068] Step S2: Construct an energy management strategy optimization model based on distributed energy storage systems and distributed photovoltaic power generation systems.

[0069] The optimization model of electric energy management strategy based on distributed energy storage system and distributed photovoltaic power generation system is as follows:

[0070] ;

[0071] in, is the comprehensive voltage deviation, is the load improvement degree, and C is the energy storage cost.

[0072] Preferably, the comprehensive voltage deviation calculation formula is as follows:

[0073] ;

[0074] in, is the voltage deviation conversion coefficient, It is the voltage deviation indicator.

[0075] The calculation formula is as follows:

[0076] ;

[0077] in, is the number of nodes, For the Node voltage deviation index, is the phase number, For cycle.

[0078] ;

[0079] in, For the Nodes Mutually The voltage value at the moment, and are the minimum and maximum values ​​of the total voltage, respectively. is the rated voltage value, and Respectively Nodes The minimum and maximum phase voltages, For the The active power of each node, is the total reactive power.

[0080] Load improvement The calculation formula is as follows:

[0081] ;

[0082] in, is the load improvement conversion factor, It is the load improvement index, and the calculation formula is as follows:

[0083] ;

[0084] in, is the average load during the period, is the original peak-to-valley difference of the power grid, is the peak-to-valley difference of the combined effect of the distributed photovoltaic power generation system and the distributed energy storage system, such as Figure 2 As shown, the calculation formula is as follows:

[0085] ;

[0086] in, and are the maximum load and minimum load of the distributed photovoltaic power generation system, and are the charging power and discharging power of the energy storage system respectively.

[0087] The calculation formula of energy storage cost C is as follows:

[0088] ;

[0089] in, is the fixed investment cost, is the energy storage operating cost, It is the peak-valley price difference profit of energy storage.

[0090] Energy storage operating costs Including maintenance costs and cable loss costs, the calculation formula is as follows:

[0091] ;

[0092] in, is the number of energy storage units, is the average maintenance cost of the energy storage unit, For the The rated capacity of each energy storage unit, is the unit line loss cost, is the number of lines, For the Line in The power loss at the moment, is the time interval.

[0093] Energy storage peak-valley price difference income The calculation formula is as follows:

[0094] ;

[0095] in, Set a period for energy storage, Set the cycle interval number for energy storage, Design loss rate for energy storage, is the energy storage utilization rate in the process of electricity price arbitrage, is the total energy storage, and are the electricity prices for charging and discharging energy storage respectively.

[0096] The constraint functions of the power management strategy optimization model include grid operation constraint function, three-phase imbalance constraint function and distributed energy storage system constraint function.

[0097] The grid operation constraint function is as follows:

[0098] ;

[0099] ;

[0100] ;

[0101] in, , , , as well as They are the active power of generator, distributed photovoltaic system, distributed energy storage system, electric vehicle and load; For the Phase Node exist The voltage amplitude at the moment, For the Phase and Di Phase-to-phase node and nodes The conductance between For the Phase and Di Phase-to-phase node and nodes The electrical susceptance between For the Phase and Di Phase-to-phase node and nodes The voltage phase angle difference between

[0102] , , , as well as They are the reactive power of generator, distributed photovoltaic system, distributed energy storage system, electric vehicle and load.

[0103] The three-phase unbalance constraint function is as follows:

[0104] ;

[0105] in, For Node exist The three-phase unbalance coefficient at the moment, It is the maximum three-phase unbalance coefficient that is set.

[0106] Preferably, the distributed energy storage system constraint function calculation formula is as follows:

[0107] ;

[0108] ;

[0109] ;

[0110] ;

[0111] in, For Node In the energy storage cycle Neidi The energy storage power for a time interval, is the energy storage energy at the initial time of the energy storage cycle, is the energy storage energy at the end of the energy storage cycle, for Energy storage at all times, is the maximum value of energy storage, It is the maximum power of energy storage. In one energy storage cycle, the total charge amount is equal to the total discharge amount, the energy capacity remains unchanged, and the energy storage energy and energy storage power are within the set range.

[0112] Step S3: Regulate the charging pile according to the output of the power management strategy optimization model.

[0113] In order to verify the superiority of this embodiment, a simulation test is performed:

[0114] Option 1: Original power grid.

[0115] Option 2: Connect to a distributed photovoltaic system.

[0116] Solution 3: Connecting the distributed photovoltaic system and the distributed energy storage system, and using the output optimization measurement of this embodiment, the results are as follows Figure 3 As shown, the technical solution of this embodiment significantly reduces the variance of power flow sensitivity, reduces the impact of electric vehicle charging on the power grid, and reduces line losses.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for managing power quality in a substation area using orderly charging and discharging of distributed energy storage, characterized in that: The specific steps are as follows: Step S1: Acquire data of the area, charging piles, distributed energy storage system and distributed photovoltaic power generation system; Step S2: Construct an optimization model for electric energy management strategy based on distributed energy storage system and distributed photovoltaic power generation system; the optimization model for electric energy management strategy based on distributed energy storage system and distributed photovoltaic power generation system is as follows: in, is the comprehensive voltage deviation, is the load improvement degree, C is the energy storage cost; The comprehensive voltage deviation calculation formula is as follows: in, is the voltage deviation conversion coefficient, It is the voltage deviation indicator; The calculation formula is as follows: in, is the number of nodes, For the Node voltage deviation index, is the phase number, For the cycle; in, For the Nodes Mutually The voltage value at the moment, and are the minimum and maximum values ​​of the total voltage, respectively. is the rated voltage value, and Respectively Nodes The minimum and maximum phase voltages, For the The active power of each node, is the total reactive power; Load improvement The calculation formula is as follows: in, is the load improvement conversion factor, It is the load improvement index, and the calculation formula is as follows: in, is the average load during the cycle, is the original peak-to-valley difference of the power grid, is the peak-to-valley difference of the composite effect of the distributed photovoltaic power generation system and the distributed energy storage system. The calculation formula is as follows: in, and are the maximum load and minimum load of the distributed photovoltaic power generation system, and are the charging power and discharging power of the energy storage system respectively; The calculation formula of energy storage cost C is as follows: in, is the fixed investment cost, is the energy storage operating cost, Profit from peak-valley price difference of energy storage; Energy storage operating costs Including maintenance costs and cable loss costs, the calculation formula is as follows: in, is the number of energy storage units, is the average maintenance cost of the energy storage unit, For the The rated capacity of each energy storage unit, is the unit line loss cost, is the number of lines, For the Line in The power loss at the moment, is the time interval; Energy storage peak-valley price difference income The calculation formula is as follows: in, Set a period for energy storage, Set the cycle interval number for energy storage, Design loss rate for energy storage, is the energy storage utilization rate in the process of electricity price arbitrage, is the total energy storage, and are the electricity prices for charging and discharging energy storage, respectively; Step S3: Regulate the charging pile according to the output of the power management strategy optimization model.

2. According to claim 1, a method for controlling power quality in a substation using orderly charging and discharging of distributed energy storage is characterized in that: In step S1, the station area data includes load data and voltage data; Charging pile data includes charging pile voltage data, load data, electric vehicle charging data and electricity price data; Distributed energy storage system data includes energy storage data, maximum energy storage data, and charging and discharging data; The distributed photovoltaic power generation system data includes the voltage data and power generation data of the distributed photovoltaic power generation system.

3. According to claim 2, a method for controlling power quality in a substation using orderly charging and discharging of distributed energy storage is characterized in that: The constraint functions of the power management strategy optimization model include grid operation constraint function, three-phase imbalance constraint function and distributed energy storage system constraint function.

4. The method for controlling power quality in a substation using orderly charging and discharging of distributed energy storage according to claim 3 is characterized in that: The grid operation constraint function is as follows: in, , , , as well as They are the active power of generator, distributed photovoltaic system, distributed energy storage system, electric vehicle and load; For the Phase Node exist The voltage amplitude at the moment, For the Phase and Di Phase-to-phase node and nodes The conductance between For the Phase and Di Phase-to-phase node and nodes The electrical susceptance between For the Phase and Di Phase-to-phase node and nodes The voltage phase angle difference between , , , as well as They are the reactive power of generator, distributed photovoltaic system, distributed energy storage system, electric vehicle and load.

5. A method for controlling power quality in a substation using orderly charging and discharging of distributed energy storage according to claim 4, characterized in that: The three-phase unbalance constraint function is as follows: in, For Node exist The three-phase unbalance coefficient at the moment, It is the maximum three-phase unbalance coefficient that is set.

6. A method for controlling power quality in a substation using orderly charging and discharging of distributed energy storage according to claim 5, characterized in that: The calculation formula of the constraint function of the distributed energy storage system is as follows: in, For Node In the energy storage cycle Neidi The energy storage power for a time interval, is the energy storage energy at the initial time of the energy storage cycle, is the energy storage energy at the end of the energy storage cycle, for Energy storage at all times, is the maximum value of energy storage, It is the maximum power of energy storage. In one energy storage cycle, the total charge amount is equal to the total discharge amount, the energy capacity remains unchanged, and the energy storage energy and energy storage power are within the set range.

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