Active-reactive support optimization method and system considering multiple operation modes of rural power grid

Abstract

The invention discloses an active-reactive power support optimization method and system considering multiple operation modes of a rural power grid, and the method comprises the steps: firstly considering a reverse discharge mode of an electric inspection vehicle configured at a rural power distribution network node, and building a rural power grid active-reactive power support optimization model with the purpose of minimizing the comprehensive power supply guarantee cost of a rural power grid system; and solving the rural power grid active-reactive power support optimization model to obtain a source load operation optimization scheme of the rural power distribution network in a networking mode and an island mode, including operation modes of an electric inspection vehicle, local new energy and an agricultural load. The reverse power supply capability of the electric inspection vehicle is utilized, the electric inspection vehicle is configured to the rural power distribution network node, the island operation capability of the rural power grid node is improved, when the rural power grid node runs in an island mode when encountering a fault, the operation mode of the electric inspection vehicle and local new energy is optimized, the degree of dependence of the rural power grid on reactive compensation facilities is effectively reduced, and the reactive compensation efficiency is improved. And the configuration cost of the reactive compensation facility is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of distribution network optimization, and particularly relates to an active-reactive power support optimization method and system considering multiple operating modes of rural power grids. Background Art

[0002] Due to the wide distribution of lines, low load density, and limited power source support capacity in rural distribution networks, compared with urban distribution networks, the power supply reliability of rural distribution networks is relatively weak. In the event of a fault, rural power grids often lack sufficient active and reactive power support capabilities, resulting in local power supply interruptions. Moreover, due to the diverse load types in rural areas, including agricultural production and residential electricity consumption loads, the uncertainty of rural power grid operation is further exacerbated. Therefore, establishing an effective support system in rural distribution networks to ensure the balance adjustment capabilities of active and reactive power not only helps improve power supply reliability but also enhances the adaptability and security of the power grid to better support the development of rural economy.

[0003] To adjust the active and reactive power balance of rural distribution networks, if simply relying on the local configuration of fixed active and reactive power sources at each rural power grid node to provide support, although it can enhance the stability of the local power grid to a certain extent, the overall cost is high, and it is difficult to flexibly adapt to the power supply demands in different regions and time periods. Especially in the case of uneven load distribution and large fluctuations in electricity demand in rural power grids, fixed configuration may lead to resource redundancy, making some equipment in a low utilization state and increasing investment and maintenance costs. Therefore, in view of the special requirements of rural distribution networks, it is necessary to explore more flexible support means to further enhance the power supply resilience of rural distribution networks and achieve the balance between reliability and economy. Summary of the Invention

[0004] The purpose of the present invention is to provide an active-reactive power support optimization method and system considering multiple operating modes of rural power grids for the above problems existing in the prior art.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows:

[0006] In the first aspect, the present invention proposes an active-reactive power support optimization method considering multiple operating modes of rural power grids, including:

[0007] S1. Considering the reverse discharge mode of the electric inspection vehicle configured at the nodes of the rural distribution network, and aiming at minimizing the comprehensive power supply guarantee cost of the rural power grid system, an active-reactive power support optimization model of the rural power grid is constructed;

[0008] S2. Solve the active-reactive power support optimization model of the rural power grid to obtain the source-load operation optimization schemes of the rural distribution network in the grid-connected mode and the island mode, including the operation modes of the electric inspection vehicle, local new energy, and agricultural load.

[0009] In the above S1, the objective function of the active-reactive power support optimization model for rural power grids includes:

[0010]

[0011]

[0012] In the above formula, t IS is the fault occurrence period. During the fault occurrence period, the island operation state and the grid-connected operation state each last for a period of time. Among them, the duration of the island operation state is T IS , and the duration of the grid-connected operation state is T U -T IS , is the curtailment cost at distribution network node e at fault occurrence period t IS , is the probability of a fault occurring at distribution network node e at fault occurrence period t IS . d is the number of typical days in a quarter. is the configuration cost of the static var generator at distribution network node e. α is the discount rate and y is the investment period. is the active base load at distribution network node e at fault occurrence period t IS , is the curtailment ratio of the base load at distribution network node e at fault occurrence period t IS . T U is the duration of each period. T IS is the fault duration. PR A is the unit cost of curtailment. is the capacity of the static var generator configured at distribution network node e. PR S is the unit configuration cost of the static var generator.

[0013] In the above S1, the constraint conditions of the active-reactive power support optimization model for rural power grids include the power source constraints under grid-connected operation and the power source constraints under island operation;

[0014] The power source constraints under grid-connected operation include:

[0015]

[0016] In the above formula, are respectively the active power output and reactive power output of the photovoltaic power connected to distribution network node e during grid-connected operation at period t, is the maximum apparent power output of the photovoltaic power connected to distribution network node e, is the output characteristic coefficient of the grid-connected operation photovoltaic at period t. cosθ GP is the minimum power factor of the photovoltaic during grid-connected operation, are the active power output and reactive power output of the wind turbine generator connected to the distribution network node e during the time period t when operating in grid-connected mode, respectively, is the maximum apparent power output of the wind turbine generator connected to the distribution network node e, is the output characteristic coefficient of the grid-connected wind turbine generator during the time period t, cosθ GW is the minimum power factor of the wind turbine generator during grid-connected operation, is the reactive power support provided by the static var generator when the distribution network node e is operating in grid-connected mode during the time period t, is the capacity of the static var generator configured at the distribution network node e;

[0017] The power source constraints under the island operation include:

[0018]

[0019] In the above formula, is the number of electric inspection vehicles configured at the distribution network node e, S Y is the rated apparent power when the electric inspection vehicle supplies power in reverse, cosθ Y is the minimum power factor when the electric inspection vehicle supplies power in reverse, are the active power and reactive power output by the electric inspection vehicle connected to the distribution network node e during the fault occurrence time period t, respectively, IS T IS is the duration of the fault, E Y is the energy that each electric inspection vehicle can use for reverse power supply, are the active power output and reactive power output of the photovoltaic power connected to the distribution network node e when operating in island mode during the fault occurrence time period t, respectively, IS is the maximum apparent power output of the photovoltaic power connected to the distribution network node e, is the output characteristic coefficient of the photovoltaic power during the fault occurrence time period t, IS cosθ IP is the minimum power factor of the photovoltaic power in island mode operation, are the active power output and reactive power output of the wind turbine generator connected to the distribution network node e when operating in island mode during the fault occurrence time period t, respectively, IS is the maximum apparent power output of the wind turbine generator connected to the distribution network node e, is the output characteristic coefficient of the wind turbine generator during the fault occurrence time period t, IS cosθ IW is the minimum power factor of the wind turbine generator in island mode operation, is the fault occurrence time period t, IS ​​Reactive power support provided by the static var generator when the distribution network node e is in island operation Capacity of the static var generator configured at the distribution network node e

[0020] In the said S1, the constraint conditions of the rural power grid active-reactive power support optimization model further include the typical agricultural load constraints in the rural power grid

[0021] The typical agricultural load constraints in the rural power grid include load demand constraints, load power constraints during grid-connected operation, and load power constraints during island operation

[0022] The said load demand constraints include:

[0023]

[0024]

[0025] In the above formula, H t，e is the heat demand of the greenhouse at the distribution network node e at time period t, A e is the area of the greenhouse that needs heating and heat preservation at the distribution network node e, ΔD t is the temperature difference between inside and outside the greenhouse, τ H is the heat conductivity coefficient of the greenhouse, T U is the duration of each time period, G t，e is the ventilation volume demand of the greenhouse at the distribution network node e at time period t is the ventilation volume required per unit area of the greenhouse

[0026] The load power constraints during grid-connected operation include:

[0027]

[0028] In the above formula are respectively the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in grid-connected operation at time period t, θ H is the power factor angle of the greenhouse heating equipment are respectively the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in grid-connected operation at time period t, K G is the energy consumed per unit ventilation volume, θ G is the power factor angle of the greenhouse ventilation equipment are respectively the active power and reactive power of the irrigation system when the distribution network node e is in grid-connected operation at time period t is the maximum power of the irrigation system at the distribution network node e are respectively the binary decision constants for the irrigation time periods in the early morning, at noon, and in the evening, θ L is the power factor angle of the irrigation system They are the irrigation demands at node e of the distribution network in the early morning, noon, and evening respectively, K L is the energy consumed for supplying a unit of water volume, They are the active power and reactive power of the residential electric vehicle charging when node e of the distribution network is in grid-connected operation at time t, E t，e is the charging demand of the residential electric vehicle at node e of the distribution network at time t, P CM is the maximum charging power of a single electric vehicle charging, is the number of electric vehicle charging piles at node e of the distribution network, θ VC is the power factor angle of the residential electric vehicle charging;

[0029] The load power constraints during island operation include:

[0030]

[0031] In the above formula, is the time period t when the fault occurs IS is the active power of the greenhouse heating equipment at node e of the distribution network at time t when the fault occurs, T IS is the duration of the fault, They are respectively the active power and reactive power of the greenhouse heating equipment at node e of the distribution network when it is in island operation at time t when the fault occurs IS , γ H is the proportion of the heat demand that can be reduced at most in the island mode, is the active power of the greenhouse ventilation equipment at node e of the distribution network at time t when the fault occurs IS , They are respectively the active power and reactive power of the greenhouse ventilation equipment at node e of the distribution network when it is in island operation at time t when the fault occurs IS , They are respectively the active power and reactive power of the irrigation system at node e of the distribution network when it is in island operation at time t when the fault occurs IS , They are respectively the binary decision constants for the auxiliary time periods in the early morning, noon, and evening, They are respectively the active power and reactive power of the residential electric vehicle reverse discharging at node e of the distribution network at time t when the fault occurs IS , P DM is the maximum charging power of a single electric vehicle reverse discharging, θ VD is the power factor angle of the residential electric vehicle reverse discharging.

[0032] In the S1, the constraint conditions of the rural power grid active-reactive power support optimization model also include the distribution network constraints under grid-connected operation and the distribution network constraints under island operation;

[0033] The constraints of the distribution network under grid-connected operation include:

[0034]

[0035] In the above formula, are respectively the active power and reactive power output from the external power grid to the distribution network node e at time period t, are respectively the active power output and reactive power output of the photovoltaic power connected to the distribution network node e during grid-connected operation at time period t, are respectively the active power output and reactive power output of the wind turbine generator connected to the distribution network node e during grid-connected operation at time period t, are respectively the active power and reactive power of the greenhouse heating equipment at the distribution network node e during grid-connected operation at time period t, are respectively the active power and reactive power of the greenhouse heating equipment at the distribution network node e during grid-connected operation at time period t, are respectively the active power and reactive power of the irrigation system at the distribution network node e during grid-connected operation at time period t, are respectively the active power and reactive power of the residential electric vehicle charging at the distribution network node e during grid-connected operation at time period t, are respectively the active basic load and reactive basic load at the distribution network node e, is the reactive power support provided by the static var generator at the distribution network node e during grid-connected operation at time period t, are respectively the active power and reactive power transmitted on the distribution network line w at time period t, ψ e，w is the binary correlation coefficient between the distribution network line w and the distribution network node e, is the line capacity of the distribution network line w, ΔU t，w is the voltage drop of the distribution network line w at time period t, are respectively the resistance and reactance of the distribution network line w, U N is the rated voltage of the distribution network node, U t，i 、U t，j are respectively the node voltages of the starting node i and the ending node j of the distribution network line at time period t, are respectively the binary correlation coefficients between the distribution network line w and the starting node i and the ending node j, U m 、U M are respectively the lower limit and upper limit of the distribution network node voltage, is the node voltage at the distribution network node e at time period t;

[0036] The constraints of the distribution network under island operation include:

[0037]

[0038] In the above formula, are respectively the active power and reactive power output by the electric inspection vehicle connected to the distribution network node e during the fault occurrence period t IS ; are respectively the active power output and reactive power output of the photovoltaic power connected to the distribution network node e during the island operation period t IS ; are respectively the active power output and reactive power output of the wind turbine generator connected to the distribution network node e during the island operation period t IS ; are respectively the active power and reactive power of the greenhouse heating equipment connected to the distribution network node e during the island operation period t IS ; are respectively the active power and reactive power of the greenhouse ventilation equipment connected to the distribution network node e during the island operation period t IS ; are respectively the active power and reactive power of the irrigation system connected to the distribution network node e during the island operation period t IS ; are respectively the active power and reactive power when the residential electric vehicle at the distribution network node e discharges reversely during the fault occurrence period t IS ; are respectively the active basic load and reactive basic load at the distribution network node e during the fault occurrence period t IS ; is the waste power ratio of the basic load at the distribution network node e during the fault occurrence period t IS ; is the reactive power support provided by the static var generator when the distribution network node e is in island operation during the fault occurrence period t IS ;

[0039] Secondly, the present invention proposes an active-reactive power support optimization system considering multiple operation modes of rural power grids, including a model construction module and a model solution module;

[0040] The model construction module is used to consider the reverse discharge mode of the electric inspection vehicle configured at the rural distribution network node, and construct an active-reactive power support optimization model for the rural power grid with the goal of minimizing the comprehensive power supply guarantee cost of the rural power grid system;

[0041] The model solution module is used to solve the active-reactive power support optimization model for the rural power grid, and obtain the source-load operation optimization scheme of the rural distribution network in the grid-connected mode and the island mode, including the operation modes of the electric inspection vehicle, local new energy, and agricultural load.

[0042] The model construction module includes an objective function construction unit;

[0043] The objective function construction unit is used to construct the objective function of the following active-reactive power support optimization model for rural power grids:

[0044]

[0045] In the above formula, t IS is the fault occurrence period. During the fault occurrence period, the island operation state and the grid-connected operation state each last for a period of time. Among them, the duration of the island operation state is t IS , and the duration of the grid-connected operation state is T U -T IS , is the curtailment cost at distribution network node e at the fault occurrence period t IS , is the probability of a fault occurring at distribution network node e at the fault occurrence period t IS . d is the number of typical days in a quarter. is the configuration cost of the static var generator at distribution network node e. α is the discount rate, and y is the investment period. is the active base load at distribution network node e at the fault occurrence period t IS , is the curtailment ratio of the base load at distribution network node e at the fault occurrence period t IS . T U is the duration of each period. T IS is the fault duration. PR A is the unit cost of curtailment. is the capacity of the static var generator configured at distribution network node e. PR S is the unit configuration cost of the static var generator.

[0046] The model construction module also includes a power supply constraint construction unit under grid-connected operation and a power supply constraint construction unit under island operation;

[0047] The power supply constraint construction unit under grid-connected operation is used to construct the following power supply constraints under grid-connected operation:

[0048]

[0049] In the above formula, are the active power output and reactive power output of the photovoltaic connected to distribution network node e during grid-connected operation at time t respectively. is the maximum apparent power output of the photovoltaic connected to distribution network node e. is the output characteristic coefficient of the grid-connected operation photovoltaic at time t. cosθ GP is the minimum power factor of the photovoltaic during grid-connected operation. are the active power output and reactive power output of the wind turbine generator connected to the distribution network node e during grid-connected operation at time period t, respectively, is the maximum apparent power output by the wind turbine generator connected to the distribution network node e, is the output characteristic coefficient of the grid-connected wind turbine generator at time period t, cosθ GW is the minimum power factor of the wind turbine generator during grid-connected operation, is the reactive power support provided by the static var generator when the distribution network node e is in grid-connected operation at time period t, is the capacity of the static var generator configured at the distribution network node e;

[0050] The power supply constraint construction unit under island operation is used to construct the following power supply constraint under island operation:

[0051]

[0052] In the above formula, is the number of electric inspection vehicles configured at the distribution network node e, S Y is the rated apparent power when the electric inspection vehicle supplies power in reverse, cosθ Y is the minimum power factor when the electric inspection vehicle supplies power in reverse, are the active power and reactive power output by the electric inspection vehicle connected to the distribution network node e at time period t during the fault occurrence, respectively, IS T IS is the duration of the fault, E Y is the energy that each electric inspection vehicle can use for reverse power supply, are the active power and reactive power output by the PV connected to the distribution network node e during island operation at time period t during the fault occurrence, respectively, IS is the maximum apparent power output by the PV connected to the distribution network node e, is the output characteristic coefficient of the PV at time period t during the fault occurrence, cosθ IS IP is the minimum power factor of the PV during island mode operation, are the active power and reactive power output by the wind turbine generator connected to the distribution network node e during island operation at time period t during the fault occurrence, respectively, IS is the maximum apparent power output by the wind turbine generator connected to the distribution network node e, is the output characteristic coefficient of the wind turbine generator at time period t during the fault occurrence, cosθ IS IW is the minimum power factor of the wind turbine generator during island mode operation, is the time period t during the fault occurrence, IS ​​​​Reactive power support provided by the static var generator when the distribution network node e is in island operation The capacity of the static var generator configured at the distribution network node e

[0053] The model construction module further includes a typical agricultural load constraint construction unit in the rural power grid

[0054] The typical agricultural load constraint construction unit in the rural power grid includes a load demand constraint construction subunit, a load power constraint construction subunit during grid-connected operation, and a load power constraint construction subunit during island operation

[0055] The load demand constraint construction subunit is used to construct the following load demand constraint

[0056]

[0057] In the above formula, H t,e is the heat demand of the greenhouse at the distribution network node e at time t, A e is the area of the greenhouse that needs heating and heat preservation at the distribution network node e, ΔD t is the temperature difference between the inside and outside of the greenhouse, τ H is the heat conductivity coefficient of the greenhouse, T U is the duration of each time period, G t，e is the ventilation volume demand of the greenhouse at the distribution network node e at time t, is the ventilation volume required per unit area of the greenhouse

[0058] The load power constraint construction subunit during grid-connected operation is used to construct the following load power constraint during grid-connected operation

[0059]

[0060]

[0061] In the above formula, are respectively the active power and reactive power of the greenhouse heating equipment at the distribution network node e during grid-connected operation at time t, θ H is the power factor angle of the greenhouse heating equipment, are respectively the active power and reactive power of the greenhouse heating equipment at the distribution network node e during grid-connected operation at time t, K G is the energy consumption per unit ventilation volume, θ G is the power factor angle of the greenhouse ventilation equipment, are respectively the active power and reactive power of the irrigation system at the distribution network node e during grid-connected operation at time t, is the maximum power of the irrigation system at the distribution network node e, Binary decision constants for the irrigation periods of morning, noon, and evening, θ L is the power factor angle of the irrigation system, are the irrigation demands at the distribution network node e during the morning, noon, and evening periods respectively, K L is the energy consumed for supplying a unit volume of water, are the active and reactive powers of the residential electric vehicle charging at the distribution network node e when it is connected to the grid during the period t, E t，e is the charging demand of the residential electric vehicle at the distribution network node e at the period t, P CM is the maximum charging power of a single electric vehicle charging, is the number of electric vehicle charging piles at the distribution network node e, θ VC is the power factor angle of the residential electric vehicle charging;

[0062] The load power constraint construction subunit during island operation is used to construct the following load power constraints during island operation:

[0063]

[0064]

[0065] In the above formula, is the fault occurrence period t IS is the active power of the greenhouse heating equipment at the distribution network node e at the period t when the fault occurs, T IS is the duration of the fault, are respectively the active and reactive powers of the greenhouse heating equipment at the distribution network node e when it is in island operation at the period t when the fault occurs IS , γ H is the proportion of the heat demand that can be reduced at most in the island mode, is the active power of the greenhouse ventilation equipment at the distribution network node e at the period t when the fault occurs IS , are respectively the active and reactive powers of the greenhouse ventilation equipment at the distribution network node e when it is in island operation at the period t when the fault occurs IS , are respectively the active and reactive powers of the irrigation system at the distribution network node e when it is in island operation at the period t when the fault occurs IS , are the binary decision constants for the auxiliary periods of morning, noon, and evening respectively, are respectively the active and reactive powers of the residential electric vehicle reverse discharging at the distribution network node e at the period t when the fault occurs IS , P DM is the maximum charging power of a single electric vehicle reverse discharging, θVD The power factor angle for the reverse power discharge of residential electric vehicles.

[0066] The model construction module further includes a distribution network constraint construction unit under grid-connected operation and a distribution network constraint construction unit under island operation;

[0067] The distribution network constraint construction unit under grid-connected operation is used to construct the following distribution network constraints under grid-connected operation:

[0068]

[0069]

[0070] In the above formula, are respectively the active power and reactive power output from the external power grid to the distribution network node e at time period t, are respectively the active power output and reactive power output of the photovoltaic power connected to the distribution network node e during grid-connected operation at time period t, are respectively the active power output and reactive power output of the wind turbine generator connected to the distribution network node e during grid-connected operation at time period t, are respectively the active power and reactive power of the greenhouse heating equipment at the distribution network node e during grid-connected operation at time period t, are respectively the active power and reactive power of the greenhouse heating equipment at the distribution network node e during grid-connected operation at time period t, are respectively the active power and reactive power of the irrigation system at the distribution network node e during grid-connected operation at time period t, are respectively the active power and reactive power of the residential electric vehicle charging at the distribution network node e during grid-connected operation at time period t, are respectively the active basic load and reactive basic load at the distribution network node e, is the reactive power support provided by the static var generator at the distribution network node e during grid-connected operation at time period t, are respectively the active power and reactive power transmitted on the distribution network line w at time period t, ψ e，w is the binary correlation coefficient between the distribution network line w and the distribution network node e, is the line capacity of the distribution network line w, ΔU t，w is the voltage drop of the distribution network line w at time period t, are respectively the resistance and reactance of the distribution network line w, U N is the rated voltage of the distribution network node, U t，i 、U t，j are respectively the node voltages of the starting node i and the ending node j of the distribution network line at time period t, are the binary correlation coefficients between the distribution network line w and the starting node i and the ending node j, respectively, U m and U M are the lower limit and upper limit of the distribution network node voltage, respectively, is the node voltage at the distribution network node e at time t;

[0071] The distribution network constraint construction unit under island operation is used to construct the following distribution network constraints under island operation:

[0072]

[0073] In the above formula, are the active power and reactive power output by the electric inspection vehicle connected to the distribution network node E at time t IS when a fault occurs, are the active power output and reactive power output of the photovoltaic power connected to the distribution network node E when the distribution network node E is in island operation at time t IS when a fault occurs, are the active power output and reactive power output of the wind turbine connected to the distribution network node e when the distribution network node e is in island operation at time t IS when a fault occurs, are the active power and reactive power of the greenhouse heating equipment when the distribution network node E is in island operation at time t IS when a fault occurs, are the active power and reactive power of the greenhouse ventilation equipment when the distribution network node E is in island operation at time t IS when a fault occurs, are the active power and reactive power of the irrigation system when the distribution network node E is in island operation at time t IS when a fault occurs, are the active power and reactive power when the residential electric vehicle at the distribution network node e discharges reversely at time t IS when a fault occurs, are the active basic load and reactive basic load at the distribution network node e at time t IS when a fault occurs, is the abandonment ratio of the basic load at the distribution network node e at time t IS when a fault occurs, is the reactive power support provided by the static var generator when the distribution network node e is in island operation at time t IS when a fault occurs.

[0074] Compared with the prior art, the beneficial effects of the present invention are:

[0075] 1. The present invention proposes an active-reactive power support optimization method and system considering multiple operation modes of rural power grids. This method first considers the reverse discharge mode of electric inspection vehicles configured at rural distribution network nodes, constructs an active-reactive power support optimization model for rural power grids with the goal of minimizing the comprehensive power supply guarantee cost of the rural power grid system; then, by solving the active-reactive power support optimization model for rural power grids, an optimized source-load operation plan for rural distribution networks in grid-connected mode and island mode is obtained, including the operation modes of electric inspection vehicles, local new energy, and agricultural loads. On the one hand, by utilizing the reverse power supply ability of electric inspection vehicles and configuring them at rural distribution network nodes, the island operation ability of rural power grid nodes is improved; on the other hand, when rural power grid nodes encounter faults and operate in island mode, by optimizing the operation modes of electric inspection vehicles and local new energy, the dependence of rural power grids on reactive power compensation facilities is effectively reduced, and the configuration cost of reactive power compensation facilities is reduced.

[0076] 2. The present invention proposes an active-reactive power support optimization method and system considering multiple operation modes of rural power grids. This method optimizes the operation of various typical agricultural loads (including ventilation, heating, and irrigation) existing in rural power grids in island mode, and reduces the load loss in island mode while ensuring agricultural production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 It is the active-reactive power support system diagram of the rural distribution network nodes described in the present invention.

[0078] Figure 2 It is the topological structure diagram of the example described in Embodiment 1.

[0079] Figure 3 It is the wind power-photovoltaic output characteristic diagram of the example described in Embodiment 1.

[0080] Figure 4 It is the heating-ventilation demand characteristic diagram of the example described in Embodiment 1.

[0081] Figure 5 It is the residential electric vehicle charging demand characteristic diagram of the example described in Embodiment 1.

[0082] Figure 6 It is the overall flowchart of the method described in the present invention.

[0083] Figure 7 It is the structure diagram of the system described in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0084] The present invention will be further described in detail below in conjunction with the specific embodiments and the accompanying drawings.

[0085] The present invention proposes an active-reactive power support optimization method and system considering multiple operation modes of rural power grids, which is used to optimize the source-load operation modes of rural distribution networks in grid-connected mode and island mode. This method is aimed at the active-reactive power support system of rural distribution network nodes as shown in Figure 1 As shown, in the grid-connected mode, the upper-level distribution network and local new energy structures such as wind power and photovoltaic power provide power support for rural power grid nodes, and the static var generator provides partial reactive power support; in the island mode, the electric inspection vehicle and residential electric vehicles enter the reverse discharge mode, and at the same time, the operation modes of local new energy structures such as wind power and photovoltaic power and flexible agricultural loads such as heating, ventilation, and irrigation are optimized to ensure that the active and reactive power balance can still be achieved at rural power grid nodes during faults.

[0086] The present invention makes full use of the reverse power supply ability of the electric inspection vehicle, configures it at rural power grid nodes, and improves the island operation ability of rural power grid nodes. At the same time, when rural power grid nodes operate in the island mode during faults, the power factor of the electric inspection vehicle (reverse power supply) and local new energy is optimized to provide partial reactive power support, reduce the dependence on reactive power compensation facilities, and optimize the operation of typical agricultural loads (ventilation, heating, irrigation) existing in the rural power grid. On the premise of ensuring the island operation ability of rural distribution network nodes and agricultural production efficiency, the comprehensive power supply guarantee cost of the system is minimized.

[0087] Example 1:

[0088] This example takes a 12-node rural distribution network as the research object, and its topological structure is as shown in Figure 2 As shown, the wind power-photovoltaic output characteristics adopted in the example are as shown in Figure 3 As shown, the heating-ventilation demand characteristics are as shown in Figure 4 As shown, the charging demand characteristics of residential electric vehicles are as shown in Figure 5As shown in the figure, the parameter settings in the example are as follows: the unit cost of abandoned electricity is 50 yuan per kilowatt-hour, the number of typical days in a quarter is 90 days, the unit time is 1 hour, the duration of a single fault is 0.25 hours, the unit configuration cost of the static var generator is 0.8 ten thousand yuan per kilovar, the discount rate is 0.05, the investment period is 10 years, the minimum power factor of photovoltaic power during grid-connected operation is 0.95, the minimum power factor of wind turbines during grid-connected operation is 0.9, the rated apparent power of the electric inspection vehicle during reverse power supply is 150 kVA, the minimum power factor of the electric inspection vehicle during reverse power supply is 0.8, the energy available for reverse power supply of each electric inspection vehicle is 30 kWh, the minimum power factor of photovoltaic power during island operation is 0.8, the minimum power factor of wind turbines during island operation is 0.8, the power factors of greenhouse heating equipment, ventilation equipment, and irrigation equipment are 0.75, 0.7, and 0.8 respectively, the heat transfer coefficient of the greenhouse is 4 W / (m²·°C), the energy consumption per unit ventilation volume is 1 Wh / m³, the energy consumption per unit water supply is 0.5 kWh / m³, the maximum charging power of a single electric vehicle is 60 kW, the power factor of residential electric vehicle charging is 0.9, the maximum proportion of heat demand reduction in island mode is 20%, the maximum charging power of a single electric vehicle during reverse discharge is 60 kW, the power factor of residential electric vehicle reverse discharge is 0.9, the rated voltage of the distribution network node is 10 kV, and the lower and upper limits of the distribution network node voltage are 9.5 kV and 10.5 kV respectively.

[0089] As Figure 6 shown, the active-reactive power support optimization method considering multiple operating modes of rural power grids is carried out in the following steps:

[0090] 1. Considering the reverse discharge mode of electric inspection vehicles configured at rural distribution network nodes, an active-reactive power support optimization model for rural power grids is constructed with the goal of minimizing the comprehensive power supply guarantee cost of the rural power grid system;

[0091] The objective function of the active-reactive power support optimization model for rural power grids includes:

[0092]

[0093] In the above formula, t IS is the fault occurrence period, referring to a short-term fault not exceeding the unit time period. During the fault occurrence period, the island operation state and the grid-connected operation state each last for a period of time, where the duration of the island operation state is T IS , and the duration of the grid-connected operation state is T U -T IS , is the abandoned electricity cost at the distribution network node e at the fault occurrence period t IS , is the fault occurrence period tIS The probability of a fault occurring at node e of the distribution network, d is the number of typical days in a quarter, is the configuration cost of the static var generator at node e of the distribution network, α is the discount rate, and y is the investment period, is the time period t when the fault occurs IS is the active base load at node e of the distribution network at time t when the fault occurs, is the time period t when the fault occurs IS is the proportion of abandoned electricity of the base load at node e of the distribution network at time t when the fault occurs, T U is the duration of each time period, T IS is the duration of the fault, PR A is the unit cost of abandoned electricity, is the capacity of the static var generator configured at node e of the distribution network, PR S is the unit configuration cost of the static var generator;

[0094] The constraint conditions of the active-reactive power support optimization model for the rural power grid include the power source constraints under grid-connected operation, the power source constraints under island operation, the typical agricultural load constraints in the rural power grid, the distribution network constraints under grid-connected operation, and the distribution network constraints under island operation;

[0095] Regarding the power source constraints under grid-connected operation and the power source constraints under island operation, it is mainly considered to use the wind power, photovoltaic power, static var generators, and electric inspection vehicles configured at the rural power grid nodes as local active and reactive power sources. When operating in grid-connected mode and island mode, the local active and reactive power sources have a certain degree of flexibility, and the rural power grid is adapted to different operating modes by optimizing their output and power factor;

[0096] The power source constraints under grid-connected operation include:

[0097] Power constraint during grid-connected operation of photovoltaic power:

[0098]

[0099] Power constraint during grid-connected operation of wind power. Among them, the wind turbines used for wind power are full-power variable-speed wind turbines, which can actively provide reactive power support and flexible adjustment:

[0100]

[0101]

[0102] Reactive power support constraint of the static var generator during grid-connected operation:

[0103]

[0104] In the above formula, the time period t is any time period within a typical day, They are the active power output and reactive power output of the PV connected when the distribution network node e is in grid-connected operation at time t, respectively. It is the maximum apparent power output of the PV connected at the distribution network node e. It is the output characteristic coefficient of the PV in grid-connected operation at time t, cosθ GP It is the minimum power factor of the PV in grid-connected operation. They are the active power output and reactive power output of the wind turbine generator connected when the distribution network node e is in grid-connected operation at time t, respectively. It is the maximum apparent power output of the wind turbine generator connected at the distribution network node e. It is the output characteristic coefficient of the wind turbine generator in grid-connected operation at time t, cosθ GW It is the minimum power factor of the wind turbine generator in grid-connected operation. It is the reactive power support provided by the static var generator when the distribution network node e is in grid-connected operation at time t. It is the capacity of the static var generator configured at the distribution network node e.

[0105] When the rural power grid node encounters a fault and operates in the island mode, optimize the reverse power supply capacity of the electric inspection vehicle and the power factor of the local new energy, reduce the dependence of the rural power grid on the reactive power compensation facilities, and improve the island operation ability of the rural power grid node. Therefore, the power source constraints under island operation include:

[0106] Output power constraint of the electric inspection vehicle under island operation mode:

[0107]

[0108] Available energy constraint of the electric inspection vehicle under island operation mode:

[0109]

[0110] Operation constraint of the PV under island operation mode:

[0111]

[0112] Operation constraint of the wind power under island operation mode:

[0113]

[0114] Reactive power support constraint of the static var generator under island operation mode:

[0115]

[0116] In the above formula, It is the number of electric inspection vehicles configured at the distribution network node e, S Yis the rated apparent power when the electric inspection vehicle supplies power in reverse, and cosθ Y is the minimum power factor when the electric inspection vehicle supplies power in reverse, are respectively the active power and reactive power output by the electric inspection vehicle connected to the distribution network node e during the fault occurrence period t IS , and T IS is the duration of the fault, and E Y is the energy available for reverse power supply for each electric inspection vehicle, are respectively the active power output and reactive power output of the photovoltaic power generation connected to the distribution network node e during the fault occurrence period t IS when the distribution network node e is in island operation, is the maximum apparent power output by the photovoltaic power generation connected to the distribution network node e, is the output characteristic coefficient of the photovoltaic power generation during the fault occurrence period t IS , and cosθ IP is the minimum power factor of the photovoltaic power generation in island mode operation, are respectively the active power output and reactive power output of the wind turbine connected to the distribution network node e during the fault occurrence period t IS when the distribution network node e is in island operation, is the maximum apparent power output by the wind turbine connected to the distribution network node e, is the output characteristic coefficient of the wind turbine during the fault occurrence period t IS , and cosθ IW is the minimum power factor of the wind turbine in island mode operation, is the reactive power support provided by the static var generator when the distribution network node e is in island operation during the fault occurrence period t IS , and is the capacity of the static var generator configured at the distribution network node e;

[0117] Regarding the typical agricultural load constraints in rural power grids, mainly considering extreme weather scenarios, such as the heating, ventilation, and irrigation of winter greenhouses, which are three typical agricultural loads. When a fault occurs, the heating and ventilation loads can be reduced in a short time, and part of the irrigation load can be transferred conditionally, so as to reduce the active and reactive support pressures of the rural power grid node in island operation during the fault while ensuring the agricultural production efficiency;

[0118] The typical agricultural load constraints in rural power grids include load demand constraints, load power constraints during grid-connected operation, and load power constraints during island operation;

[0119] The load demand constraints include:

[0120] Heating demand constraints:

[0121] ​

[0122] Ventilation demand constraint:

[0123]

[0124] In the above formula, H t，e is the heat demand of the greenhouse at the distribution network node e at time t, A e is the area of the greenhouse that needs heating and heat preservation at the distribution network node e, ΔD t is the temperature difference between inside and outside the greenhouse, τ H is the heat conductivity coefficient of the greenhouse, T U is the duration of each time period, G t，e is the ventilation volume demand of the greenhouse at the distribution network node e at time t, is the ventilation volume required per unit area of the greenhouse;

[0125] The load power constraints during grid-connected operation include:

[0126] The active and reactive power constraints of the heating load during grid-connected operation:

[0127]

[0128] The active and reactive power constraints of the ventilation load during grid-connected operation

[0129]

[0130] The active and reactive power constraints of the irrigation load during grid-connected operation

[0131]

[0132] The irrigation demand constraints at different times during grid-connected operation. Considering three irrigation periods in a day, the irrigation system is only allowed to work during these periods:

[0133]

[0134] The charging demand and power constraints of residential electric vehicles during grid-connected operation:

[0135]

[0136] In the above formula, are respectively the active power and reactive power of the greenhouse heating equipment at the distribution network node e at time t during grid-connected operation, θ H is the power factor angle of the greenhouse heating equipment, are respectively the active power and reactive power of the greenhouse heating equipment at the distribution network node e at time t during grid-connected operation, K G is the energy consumed per unit ventilation volume, θ G is the power factor angle of the greenhouse ventilation equipment, are the active power and reactive power of the irrigation system when the distribution network node e is in grid-connected operation at time period t, respectively, is the maximum power of the irrigation system at the distribution network node e, are the binary determination constants for the irrigation time periods in the early morning, noon, and evening, respectively. When it is 1, it means that the time period t is in this irrigation time period, θ L is the power factor angle of the irrigation system, are the irrigation demands at the distribution network node e in the early morning, noon, and evening time periods, respectively, K L is the energy consumed for supplying a unit of water volume, are the active power and reactive power of the residential electric vehicle charging when the distribution network node e is in grid-connected operation at time period t, respectively, E t，e is the charging demand of the residential electric vehicle at the distribution network node e at time period t, P CM is the maximum charging power for a single electric vehicle charging, is the number of electric vehicle charging piles at the distribution network node e, θ VC is the power factor angle of the residential electric vehicle charging;

[0137] The load power constraints during islanding operation include:

[0138] The active and reactive power constraints of the heating load under the islanding operation mode:

[0139]

[0140] The active and reactive power constraints of the ventilation load under the islanding operation mode:

[0141]

[0142] The active and reactive power constraints of the irrigation load during islanding operation:

[0143]

[0144] During islanding operation, the irrigation demand constraints for different time periods:

[0145]

[0146] The charging demand and power constraints of the residential electric vehicle during islanding operation:

[0147]

[0148]

[0149] In the above formula, is the time period t when the fault occurs IS is the active power of the greenhouse heating equipment at the distribution network node e at time period t, TIS is the duration of the fault, are respectively the fault occurrence time period t IS when the greenhouse heating equipment has active power and reactive power at the distribution network node e in island operation, γ H is the proportion of the heat demand that can be reduced at most in the island mode, is the fault occurrence time period t IS when the active power of the greenhouse ventilation equipment at the distribution network node e, are respectively the fault occurrence time period t IS when the greenhouse ventilation equipment has active power and reactive power at the distribution network node e in island operation, are respectively the fault occurrence time period t IS when the irrigation system has active power and reactive power at the distribution network node e in island operation, are respectively the binary decision constants for the auxiliary time periods in the morning, at noon, and in the evening. For any fault occurrence time period t IS , t = t IS when is 0, and for the remaining time periods t are all 1, are respectively the fault occurrence time period t IS when the active power and reactive power of the residential electric vehicle reverse discharge at the distribution network node e, P DM is the maximum charging power of a single electric vehicle reverse discharge, θ VD is the power factor angle of the residential electric vehicle reverse discharge;

[0150] For the constraints of the distribution network under grid-connected operation and the constraints of the distribution network under island operation;

[0151] The constraints of the distribution network under grid-connected operation include:

[0152] Under grid-connected operation, the active and reactive power balance constraints of the distribution network:

[0153]

[0154] The distribution network line capacity constraint:

[0155]

[0156] The distribution network node voltage constraint:

[0157]

[0158] In the above formula, are respectively the active power and reactive power output from the external power grid to the distribution network node e at the time period t, are the active power output and reactive power output of the PV connected when the distribution network node e is in grid-connected operation at time t, respectively, are the active power output and reactive power output of the wind turbine connected when the distribution network node e is in grid-connected operation at time t, respectively, are the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in grid-connected operation at time t, respectively, are the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in grid-connected operation at time t, respectively, are the active power and reactive power of the irrigation system when the distribution network node e is in grid-connected operation at time t, respectively, are the active power and reactive power of the residential electric vehicle charging when the distribution network node e is in grid-connected operation at time t, respectively, are the active basic load and reactive basic load at the distribution network node e at time t, respectively, is the reactive power support provided by the static var generator when the distribution network node e is in grid-connected operation at time t, are the active power and reactive power transmitted on the distribution network line w at time t, ψ e,w is the binary correlation coefficient between the distribution network line w and the distribution network node e. When it is 1, the distribution network line w is connected to the distribution network node e, is the line capacity of the distribution network line w, ΔU t,w is the voltage drop of the distribution network line w at time t, are the resistance and reactance of the distribution network line w, U N is the rated voltage of the distribution network node, U t，i 、U t，j are the node voltages of the starting node i and the ending node j of the distribution network line at time t, respectively, are the binary correlation coefficients between the distribution network line w and the starting node i and the ending node j. When is 1, the node i is the starting node of the distribution network line w. When is 1, the node j is the ending node of the distribution network line w, U m 、U M are the lower limit and upper limit of the distribution network node voltage, respectively, is the node voltage at the distribution network node e at time t;

[0159] The constraints of the distribution network under island operation include:

[0160] Under fault conditions, the power balance constraint when the distribution network node operates in the island mode:

[0161]

[0162] In the above formula, are respectively the active power and reactive power output by the electric inspection vehicle connected to node e of the distribution network during the fault occurrence period t IS ; are respectively the active power output and reactive power output of the photovoltaic power connected to node e of the distribution network during the fault occurrence period t IS when it is in island operation; are respectively the active power output and reactive power output of the wind turbine generator connected to node e of the distribution network during the fault occurrence period t IS when it is in island operation; are respectively the active power and reactive power of the greenhouse heating equipment connected to node e of the distribution network during the fault occurrence period t IS when it is in island operation; are respectively the active power and reactive power of the greenhouse ventilation equipment connected to node e of the distribution network during the fault occurrence period t IS when it is in island operation; are respectively the active power and reactive power of the irrigation system connected to node e of the distribution network during the fault occurrence period t IS when it is in island operation; are respectively the active power and reactive power when the residential electric vehicle at node e of the distribution network discharges reversely during the fault occurrence period t IS ; are respectively the active basic load and reactive basic load at node e of the distribution network during the fault occurrence period t IS ; is the curtailment ratio of the basic load at node e of the distribution network during the fault occurrence period t IS ; is the reactive power support provided by the static var generator when node e of the distribution network is in island operation during the fault occurrence period t IS .

[0163] 2. Perform simulation operation based on the MATLAB / CPLEX platform, solve the active-reactive power support optimization model of the rural power grid, and obtain the source-load operation optimization schemes of the rural distribution network in the grid-connected mode and island mode, including the operation modes of electric inspection vehicles, local new energy, and agricultural loads;

[0164] The parameter settings of the hardware equipment of the simulation platform are: Intel Core i7-9750H, 32G RAM, 2.6GHz.

[0165] To verify the effectiveness of this solution, an operation optimization method that only uses local power for island power support is introduced as Method 2. Both this method proposed in this solution (Method 1) and Method 2 are applied to the 12-node rural distribution network example for comparison. Among them, Method 2 does not consider the power support of the electric inspection vehicle and does not optimize the local distributed power sources and flexible loads. The comparison of the comprehensive power supply security costs of the two methods is shown in Table 1:

[0166] Table 1 Comparison table of comprehensive power supply security costs

[0167]

[0168] Table 1 lists the configuration costs, curtailment costs, and comprehensive power supply security costs of the static var generator per quarter when using the two methods. It can be seen from Table 1 that when using Method 1 compared with Method 2, the configuration cost of the static var generator is reduced by 11.31%, the curtailment cost is reduced by 16.91%, and the comprehensive power supply security cost is reduced by 12.76%. The above results show that the active-reactive power support optimization method considering multiple operation modes of the rural power grid proposed in this solution achieves the effect of minimizing the comprehensive power supply security cost of the rural power grid system on the premise of ensuring the island operation ability of the rural distribution network nodes and the agricultural production efficiency.

[0169] Example 2:

[0170] As Figure 7 shown, the active-reactive power support optimization system considering multiple operation modes of the rural power grid includes a model construction module and a model solution module;

[0171] The model construction module is used to consider the reverse discharge mode of the electric inspection vehicle configured at the rural distribution network nodes, and construct an active-reactive power support optimization model for the rural power grid with the goal of minimizing the comprehensive power supply security cost of the rural power grid system;

[0172] The model solution module is used to solve the active-reactive power support optimization model for the rural power grid and obtain the source-load operation optimization scheme of the rural distribution network in the grid-connected mode and the island mode, including the operation modes of the electric inspection vehicle, local new energy, and agricultural loads.

[0173] The model construction module includes an objective function construction unit, a power source constraint construction unit under grid-connected operation, a power source constraint construction unit under island operation, a typical agricultural load constraint construction unit in the rural power grid, a distribution network constraint construction unit under grid-connected operation, and a distribution network constraint construction unit under island operation;

[0174] The objective function construction unit is used to construct the objective function of the active-reactive power support optimization model for the rural power grid as shown in Example 1;

[0175] The power constraint construction unit under grid-connected operation is used to construct the power constraint under grid-connected operation as shown in Embodiment 1;

[0176] The power constraint construction unit under island operation is used to construct the power constraint under island operation as shown in Embodiment 1;

[0177] The typical agricultural load constraint construction unit in the rural power grid includes a load demand constraint construction subunit, a load power constraint construction subunit during grid-connected operation, and a load power constraint construction subunit during island operation;

[0178] The load demand constraint construction subunit is used to construct the load demand constraint as shown in Embodiment 1;

[0179] The load power constraint construction subunit during grid-connected operation is used to construct the load power constraint during grid-connected operation as shown in Embodiment 1;

[0180] The load power constraint construction subunit during island operation is used to construct the load power constraint during island operation as shown in Embodiment 1;

[0181] The distribution network constraint construction unit under grid-connected operation is used to construct the distribution network constraint under grid-connected operation as shown in Embodiment 1;

[0182] The distribution network constraint construction unit under island operation is used to construct the distribution network constraint under island operation as shown in Embodiment 1.

Claims

1. An active-reactive power support optimization method considering multiple operation modes of rural power grids, characterized in that: The method includes: S1. Considering the reverse discharge mode of the electric inspection vehicle configured at the nodes of the rural distribution network, taking the minimization of the comprehensive power supply guarantee cost of the rural power grid system as the goal, and constructing an active-reactive power support optimization model for the rural power grid; S2. Solving the active-reactive power support optimization model for the rural power grid to obtain the optimized source-load operation schemes of the rural distribution network in the grid-connected mode and the island mode, including the operation modes of the electric inspection vehicle, local new energy, and agricultural load.

2. The active-reactive power support optimization method considering multiple operation modes of rural power grids according to claim 1, characterized in that: In the S1, the objective function of the active-reactive power support optimization model for the rural power grid includes: In the above formula, t IS is the fault occurrence period. During the fault occurrence period, the island operation state and the grid-connected operation state each last for a period of time. The duration of the island operation state is T IS , and the duration of the grid-connected operation state is T U -T IS . is the electricity abandonment cost at the distribution network node e during the fault occurrence period t IS . is the probability of a fault occurring at the distribution network node e during the fault occurrence period t IS . d is the number of typical days in a quarter is the configuration cost of the static var generator at the distribution network node e. α is the discount rate and y is the investment period is the active base load at the distribution network node e during the fault occurrence period t IS . is the electricity abandonment ratio of the base load at the distribution network node e during the fault occurrence period t IS . T U is the duration of each period. T IS is the fault duration. PR A is the unit cost of electricity abandonment is the capacity of the static var generator configured at the distribution network node e. PR S is the unit configuration cost of the static var generator 3. The active-reactive power support optimization method considering multiple operation modes of rural power grids according to claim 1, characterized in that: In the S1, the constraint conditions of the active-reactive power support optimization model for the rural power grid include the power supply constraints under grid-connected operation and the power supply constraints under island operation; The power supply constraints under grid-connected operation include: In the above formula, are the active power output and reactive power output of the photovoltaic power connected to the distribution network node e during the time period t when it is connected to the grid, respectively, is the maximum apparent power output of the photovoltaic power connected to the distribution network node e, is the output characteristic coefficient of the photovoltaic power connected to the grid during the time period t, cosθ GP is the minimum power factor of the photovoltaic power when it is connected to the grid, are the active power output and reactive power output of the wind turbine connected to the distribution network node e during the time period t when it is connected to the grid, respectively, is the maximum apparent power output of the wind turbine connected to the distribution network node e, is the output characteristic coefficient of the wind turbine connected to the grid during the time period t, cosθ GW is the minimum power factor of the wind turbine when it is connected to the grid, is the reactive power support provided by the static var generator when the distribution network node e is connected to the grid during the time period t, is the capacity of the static var generator configured at the distribution network node e; The power supply constraints under island operation include: In the above formula, is the number of electric inspection vehicles configured at the distribution network node e, S Y is the rated apparent power when the electric inspection vehicle supplies power in reverse, cosθ Y is the minimum power factor when the electric inspection vehicle supplies power in reverse, are respectively the active power and reactive power output by the electric inspection vehicles connected to the distribution network node e during the fault occurrence period t IS ; T IS is the duration of the fault, E Y is the energy available for reverse power supply for each electric inspection vehicle, are respectively the active power output and reactive power output of the photovoltaic power generation connected to the distribution network node e during the fault occurrence period t IS when it is in island operation; is the maximum apparent power output by the photovoltaic power generation connected to the distribution network node e, is the output characteristic coefficient of the photovoltaic power generation during the fault occurrence period t IS ; cosθ IP is the minimum power factor of the photovoltaic power generation in island mode operation, are respectively the active power output and reactive power output of the wind turbine connected to the distribution network node e during the fault occurrence period t IS when it is in island operation; is the maximum apparent power output by the wind turbine connected to the distribution network node e, is the output characteristic coefficient of the wind turbine during the fault occurrence period t IS ; cosθ IW is the minimum power factor of the wind turbine in island mode operation, is the reactive power support provided by the static var generator when the distribution network node e is in island operation during the fault occurrence period t IS ; is the capacity of the static var generator configured at the distribution network node e.

4. The active-reactive power support optimization method considering multiple operation modes of rural power grids according to claim 1, characterized in that: In the S1, the constraint conditions of the active-reactive power support optimization model for the rural power grid also include the typical agricultural load constraints in the rural power grid; The typical agricultural load constraints in the rural power grid include load demand constraints, load power constraints during grid-connected operation, and load power constraints during island operation; The load demand constraints include: In the above formula, H t，e is the heat demand of the greenhouse at the distribution network node e at time period t, A e is the area of the greenhouse that needs heating and heat preservation at the distribution network node e, ΔD t is the temperature difference between the inside and outside of the greenhouse, τ H is the heat conductivity coefficient of the greenhouse, T U is the duration of each time period, G t，e is the ventilation volume demand of the greenhouse at the distribution network node e at time period t, is the ventilation volume required per unit area of the greenhouse; The load power constraints during grid-connected operation include: In the above formula, are the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in grid-connected operation at time t, respectively, and θ H is the power factor angle of the greenhouse heating equipment, are the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in grid-connected operation at time t, respectively, and K G is the energy consumption per unit ventilation volume, and θ G is the power factor angle of the greenhouse ventilation equipment, are the active power and reactive power of the irrigation system when the distribution network node e is in grid-connected operation at time t, respectively, is the maximum power of the irrigation system at the distribution network node e, are the binary decision constants for the irrigation periods in the early morning, noon, and evening, respectively, and θ L is the power factor angle of the irrigation system, are the irrigation demands at the distribution network node e in the early morning, noon, and evening periods, respectively, and K L is the energy consumption for supplying a unit volume of water, are the active power and reactive power of the residential electric vehicle charging when the distribution network node e is in grid-connected operation at time t, respectively, and E t，e is the charging demand of the residential electric vehicle at the distribution network node e at time t, and P CM is the maximum charging power for single electric vehicle charging, is the number of electric vehicle charging piles at the distribution network node e, and θ VC is the power factor angle of the residential electric vehicle charging; The load power constraints during island operation include: In the above formula, is the active power of the greenhouse heating equipment at the distribution network node e during the fault occurrence period t IS while T IS is the fault duration, are respectively the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in island operation during the fault occurrence period t IS and γ H is the proportion of the heat demand that can be reduced at most in the island mode, is the active power of the greenhouse ventilation equipment at the distribution network node e during the fault occurrence period t IS , are respectively the active power and reactive power of the greenhouse ventilation equipment when the distribution network node e is in island operation during the fault occurrence period t IS , are respectively the active power and reactive power of the irrigation system when the distribution network node e is in island operation during the fault occurrence period t IS , are respectively the binary decision constants for the auxiliary periods in the morning, noon, and evening, are respectively the active power and reactive power of the reverse power discharge of the residential electric vehicle at the distribution network node e during the fault occurrence period t IS , P DM is the maximum charging power of a single electric vehicle for reverse power discharge, and θ VD is the power factor angle of the reverse power discharge of the residential electric vehicle.

5. The active-reactive power support optimization method considering multiple operation modes of rural power grids according to claim 1, characterized in that: In the S1, the constraint conditions of the active-reactive power support optimization model for the rural power grid also include the distribution network constraints under grid-connected operation and the distribution network constraints under island operation; The distribution network constraints under grid-connected operation include: In the above formula, are the active power and reactive power output from the external power grid to the distribution network node e at time period t, respectively, are the active power output and reactive power output of the photovoltaic power generation connected to the distribution network node e during grid-connected operation at time period t, respectively, are the active power output and reactive power output of the wind turbine generator connected to the distribution network node e during grid-connected operation at time period t, respectively, are the active power and reactive power of the greenhouse heating equipment at the distribution network node e during grid-connected operation at time period t, respectively, are the active power and reactive power of the greenhouse heating equipment at the distribution network node e during grid-connected operation at time period t, respectively, are the active power and reactive power of the irrigation system at the distribution network node e during grid-connected operation at time period t, respectively, are the active power and reactive power of the residential electric vehicle charging at the distribution network node e during grid-connected operation at time period t, respectively, are the active basic load and reactive basic load at the distribution network node e at time period t, respectively, is the reactive power support provided by the static var generator when the distribution network node e is in grid-connected operation at time period t, are the active power and reactive power transmitted on the distribution network line w at time period t, ψ e，w is the binary correlation coefficient between the distribution network line w and the distribution network node e, is the line capacity of the distribution network line w, ΔU t，w is the voltage drop of the distribution network line w at time period t, are the resistance and reactance of the distribution network line w, respectively, U N is the rated voltage of the distribution network node, U t，i 、U t，j are the node voltages of the starting node i and the ending node j of the distribution network line at time period t, respectively, are the binary correlation coefficients between the distribution network line w and the starting node i and the ending node j, respectively, U m 、U M are the lower limit and upper limit of the distribution network node voltage, respectively, is the node voltage at the distribution network node e at time period t; The distribution network constraints under island operation include: In the above formula, are respectively the active power and reactive power output by the electric inspection vehicle connected to node e of the distribution network during the fault occurrence period t IS ; are respectively the active power output and reactive power output of the photovoltaic power generation connected to node e of the distribution network during the island operation period t IS ; are respectively the active power output and reactive power output of the wind turbine connected to node e of the distribution network during the island operation period t IS ; are respectively the active power and reactive power of the greenhouse heating equipment connected to node e of the distribution network during the island operation period t IS ; are respectively the active power and reactive power of the greenhouse ventilation equipment connected to node e of the distribution network during the island operation period t IS ; are respectively the active power and reactive power of the irrigation system connected to node e of the distribution network during the island operation period t IS ; are respectively the active power and reactive power when the residential electric vehicle at node e of the distribution network discharges reversely during the fault occurrence period t IS ; are respectively the active basic load and reactive basic load at node e of the distribution network during the fault occurrence period t IS ; is the abandonment ratio of the basic load at node e of the distribution network during the fault occurrence period t IS ; is the reactive power support provided by the static var generator when node e of the distribution network is in island operation during the fault occurrence period t IS .

6. An active-reactive power support optimization system considering multiple operation modes of rural power grids, characterized in that: The system includes a model construction module and a model solution module; The model construction module is used to consider the reverse discharge mode of the electric inspection vehicle configured at the nodes of the rural distribution network, taking the minimization of the comprehensive power supply guarantee cost of the rural power grid system as the goal, and constructing an active-reactive power support optimization model for the rural power grid; The model solution module is used to solve the active-reactive power support optimization model for the rural power grid to obtain the optimized source-load operation schemes of the rural distribution network in the grid-connected mode and the island mode, including the operation modes of the electric inspection vehicle, local new energy, and agricultural load.

7. The active-reactive power support optimization system considering multiple operation modes of rural power grids according to claim 6, characterized in that: The model construction module includes an objective function construction unit; The objective function construction unit is used to construct the following objective function of the active-reactive power support optimization model for the rural power grid: In the above formula, t IS is the fault occurrence period. During the fault occurrence period, the islanded operation state and the grid-connected operation state each last for a period of time. The duration of the islanded operation state is T IS , and the duration of the grid-connected operation state is T U -T IS . is the curtailment cost at the distribution network node e during the fault occurrence period t IS . is the probability of a fault occurring at the distribution network node e during the fault occurrence period t IS . d is the number of typical days in a quarter is the configuration cost of the static var generator at the distribution network node e. α is the discount rate, and y is the investment period is the active base load at the distribution network node e during the fault occurrence period t IS . is the curtailment ratio of the base load at the distribution network node e during the fault occurrence period t IS . T U is the duration of each period. T IS is the fault duration. PR A is the unit cost of curtailment is the capacity of the static var generator configured at the distribution network node e. PR S is the unit configuration cost of the static var generator 8. The active-reactive power support optimization system considering multiple operation modes of rural power grids according to claim 6, characterized in that: The model construction module further includes a power supply constraint construction unit under grid-connected operation and a power supply constraint construction unit under island operation; The power supply constraint construction unit under grid-connected operation is used to construct the following power supply constraints under grid-connected operation: In the above formula, are the active power output and reactive power output of the PV connected to the distribution network node e during the time period t when it is operating in parallel, is the maximum apparent power output of the PV connected at the distribution network node e, is the output characteristic coefficient of the PV operating in parallel during the time period t, cosθ GP is the minimum power factor of the PV when operating in parallel, are the active power output and reactive power output of the wind turbine connected to the distribution network node e during the time period t when it is operating in parallel, is the maximum apparent power output of the wind turbine connected at the distribution network node e, is the output characteristic coefficient of the wind turbine operating in parallel during the time period t, cosθ GW is the minimum power factor of the wind turbine when operating in parallel, is the reactive power support provided by the static var generator when the distribution network node e is operating in parallel during the time period t, is the capacity of the static var generator configured at the distribution network node e; The power supply constraint construction unit under island operation is used to construct the following power supply constraints under island operation: In the above formula, is the number of electric inspection vehicles configured at the distribution network node e, and S Y is the rated apparent power when the electric inspection vehicle supplies power in reverse, and cosθ Y is the minimum power factor when the electric inspection vehicle supplies power in reverse. are the active power and reactive power output by the electric inspection vehicles connected to the distribution network node e during the fault occurrence period t IS respectively, T IS is the duration of the fault, and E Y is the energy that each electric inspection vehicle can use for reverse power supply. are the active power output and reactive power output of the photovoltaic power connected to the distribution network node e during the fault occurrence period t IS when it is in island operation respectively, is the maximum apparent power output by the photovoltaic power connected to the distribution network node e, is the output characteristic coefficient of the photovoltaic power during the fault occurrence period t IS , and cosθ IP is the minimum power factor of the photovoltaic power in island mode operation. are the active power output and reactive power output of the wind turbine generator connected to the distribution network node e during the fault occurrence period t IS when it is in island operation respectively, is the maximum apparent power output by the wind turbine generator connected to the distribution network node e, is the output characteristic coefficient of the wind turbine generator during the fault occurrence period t IS , and cosθ IW is the minimum power factor of the wind turbine generator in island mode operation. is the reactive power support provided by the static var generator when the distribution network node e is in island operation during the fault occurrence period t IS , and is the capacity of the static var generator configured at the distribution network node e.​ 9. The active-reactive power support optimization system considering multiple operation modes of rural power grids according to claim 6, characterized in that The model construction module further includes a typical agricultural load constraint construction unit in the rural power grid; The typical agricultural load constraint construction unit in the rural power grid includes a load demand constraint construction subunit, a load power constraint construction subunit during grid-connected operation, and a load power constraint construction subunit during island operation; The load demand constraint construction subunit is used to construct the following load demand constraints: In the above formula, H t，e is the heat demand of the greenhouse at the distribution network node e at time period t, A e is the area of the greenhouse that needs to be heated and insulated at the distribution network node e, ΔD t is the temperature difference between inside and outside the greenhouse, τ H is the heat conductivity coefficient of the greenhouse, T U is the duration of each time period, G t，e is the ventilation volume demand of the greenhouse at the distribution network node e at time period t, is the ventilation volume required per unit area of the greenhouse; The load power constraint construction subunit during grid-connected operation is used to construct the following load power constraints during grid-connected operation: In the above formula, are the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in grid-connected operation at time t, respectively, and θ H is the power factor angle of the greenhouse heating equipment, are the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in grid-connected operation at time t, respectively, and K G is the energy consumption per unit ventilation volume, and θ G is the power factor angle of the greenhouse ventilation equipment, are the active power and reactive power of the irrigation system when the distribution network node e is in grid-connected operation at time t, respectively, is the maximum power of the irrigation system at the distribution network node e, are the binary determination constants for the irrigation time periods in the early morning, noon, and evening, respectively, and θ L is the power factor angle of the irrigation system, are the irrigation demands at the distribution network node e in the early morning, noon, and evening time periods, respectively, and K L is the energy consumption for supplying a unit volume of water, are the active power and reactive power of the residential electric vehicle charging when the distribution network node e is in grid-connected operation at time t, respectively, and E t，e is the charging demand of the residential electric vehicle at the distribution network node e at time t, and P CM is the maximum charging power for a single electric vehicle charging, is the number of electric vehicle charging piles at the distribution network node e, and θ VC is the power factor angle of the residential electric vehicle charging; The load power constraint construction subunit during island operation is used to construct the following load power constraints during island operation: In the above formula, is the active power of the greenhouse heating equipment at the distribution network node e during the fault occurrence period t IS and T IS is the duration of the fault. are respectively the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in island operation during the fault occurrence period t IS and γ H is the proportion of the heat demand that can be reduced at most in the island mode. is the active power of the greenhouse ventilation equipment at the distribution network node e during the fault occurrence period t IS and are respectively the active power and reactive power of the greenhouse ventilation equipment when the distribution network node e is in island operation during the fault occurrence period t IS and are respectively the active power and reactive power of the irrigation system when the distribution network node e is in island operation during the fault occurrence period t IS and are respectively the binary decision constants for the auxiliary periods in the morning, at noon, and in the evening. are respectively the active power and reactive power of the reverse power discharge of the residential electric vehicle at the distribution network node e during the fault occurrence period t IS and P DM is the maximum charging power of a single electric vehicle for reverse power discharge, and θ VD is the power factor angle of the reverse power discharge of the residential electric vehicle.​​​ 10. The active-reactive power support optimization system considering multiple operation modes of rural power grids according to claim 6, characterized in that The model construction module further includes a distribution network constraint construction unit under grid-connected operation and a distribution network constraint construction unit under island operation; The distribution network constraint construction unit under grid-connected operation is used to construct the following distribution network constraints under grid-connected operation: In the above formula, are the active power and reactive power output from the external power grid to the distribution network node e at time period t, respectively, are the active power output and reactive power output of the photovoltaic power connected when the distribution network node e is in grid-connected operation at time period t, respectively, are the active power output and reactive power output of the wind turbine generator connected when the distribution network node e is in grid-connected operation at time period t, respectively, are the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in grid-connected operation at time period t, respectively, are the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in grid-connected operation at time period t, respectively, are the active power and reactive power of the irrigation system when the distribution network node e is in grid-connected operation at time period t, respectively, are the active power and reactive power of the residential electric vehicle charging when the distribution network node e is in grid-connected operation at time period t, respectively, are the active basic load and reactive basic load at the distribution network node e at time period t, respectively, is the reactive power support provided by the static var generator when the distribution network node e is in grid-connected operation at time period t, are the active power and reactive power transmitted on the distribution network line w at time period t, ψ e，w is the binary correlation coefficient between the distribution network line w and the distribution network node e, is the line capacity of the distribution network line w, ΔU t，w is the voltage drop of the distribution network line w at time period t, are the resistance and reactance of the distribution network line w, respectively, U N is the rated voltage of the distribution network node, U t，i 、U t，j are the node voltages of the starting node i and the ending node j of the distribution network line at time period t, respectively, are the binary correlation coefficients between the distribution network line w and the starting node i and the ending node j, respectively, U M 、U M are the lower limit and upper limit of the distribution network node voltage, respectively, is the node voltage at the distribution network node e at time period t; The distribution network constraint construction unit under island operation is used to construct the following distribution network constraints under island operation: In the above formula, are the active power and reactive power output by the electric inspection vehicle connected to the distribution network node e during the fault occurrence period t IS respectively, are the active power output and reactive power output of the photovoltaic power connected when the distribution network node e is in island operation during the fault occurrence period t IS respectively, are the active power output and reactive power output of the wind turbine generator connected when the distribution network node e is in island operation during the fault occurrence period t IS respectively, are the active power and reactive power of the greenhouse heating equipment when the distribution network node e is in island operation during the fault occurrence period t IS respectively, are the active power and reactive power of the greenhouse ventilation equipment when the distribution network node e is in island operation during the fault occurrence period t IS respectively, are the active power and reactive power of the irrigation system when the distribution network node e is in island operation during the fault occurrence period t IS respectively, are the active power and reactive power when the residential electric vehicle at the distribution network node e discharges in reverse during the fault occurrence period t IS respectively, are the active basic load and reactive basic load at the distribution network node e during the fault occurrence period t IS respectively, is the curtailment ratio of the basic load at the distribution network node e during the fault occurrence period t IS respectively, is the reactive power support provided by the static var generator when the distribution network node e is in island operation during the fault occurrence period t IS respectively.

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