A method and system for coordinating control of grid-connected photovoltaic power generation and electric vehicle charging

Abstract

This invention relates to the field of distribution network operation and control technology, and particularly to a method and system for suppressing photovoltaic backfeeding and coordinating control of electric vehicles in rural power grids. The method includes: dividing the rural power grid feeder into zones based on a radial rural feeder topology and calculating the voltage sensitivity of each zone; constructing an objective function with the upper-level rural power grid control center as the main body, and determining the aggregated power adjustment range of electric vehicles and photovoltaic reactive power control parameters for each zone; determining the aggregated charging and discharging power of electric vehicles under the constraint of the aggregated power adjustment range; and coordinating the control of the rural power grid feeder based on the photovoltaic reactive power control parameters and the aggregated charging and discharging power. This invention effectively solves the problem of difficulty in suppressing photovoltaic backfeeding due to differences in voltage sensitivity between different zones under a rural radial feeder structure. By coordinating the control of photovoltaic reactive power and the aggregated charging and discharging behavior of electric vehicles, coordinated control of photovoltaic backfeeding suppression and rural power grid operation status is achieved.

Description

Technical Field

[0001] This invention relates to the field of power distribution network operation and control technology, and in particular to a method and system for suppressing backfeeding from rural photovoltaic power grids and coordinating control with electric vehicles. Background Technology

[0002] In rural power distribution networks, distribution lines often adopt a radial feeder structure, which is relatively long and has high impedance. Different feeder sections exhibit significant differences in voltage response characteristics to power changes. With the concentrated integration of distributed photovoltaic (PV) systems in rural areas, when the PV output in a local area exceeds the local load demand, power can easily be fed back to the upper-level grid at the feeder or transformer substation level, leading to issues such as increased node voltage or even exceeding limits.

[0003] Existing control methods for photovoltaic backfeeding in rural distribution networks typically rely on reactive power regulation of photovoltaic inverters or photovoltaic power limiting, implementing unified control over the entire feeder or distribution area. This fails to differentiate control based on the voltage sensitivity of different feeder zones. Furthermore, although electric vehicles are becoming increasingly common in rural areas, their adjustable charging and discharging power gives them the potential to absorb excess energy during periods of high photovoltaic output. However, current technologies primarily utilize electric vehicles as independent loads, lacking a coordinated control mechanism that integrates their operation with photovoltaic output characteristics and feeder voltage conditions. Summary of the Invention

[0004] This invention provides a method for suppressing backfeeding from rural photovoltaic power grids and coordinating control of electric vehicles, which can effectively solve the problems in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for suppressing backflow of photovoltaic power in rural areas and coordinating control of electric vehicles, the method comprising: Based on the radial rural feeder topology, the rural power grid feeder is divided into zones, and the voltage sensitivity of each zone is calculated. Based on the voltage sensitivity of the zones, and taking the upper-level rural power grid control center as the main body, an objective function is constructed, and the aggregate power adjustment range of electric vehicles and photovoltaic reactive power control parameters of each zone are determined. Under the condition of satisfying the aforementioned aggregate power adjustment range constraint, determine the aggregate charging and discharging power of the electric vehicle; Based on the photovoltaic reactive power control parameters and the aggregated charging and discharging power, the rural power grid feeder is synergistically regulated.

[0006] Furthermore, the voltage sensitivity is modeled using a linearized DistFlow model, which is expressed as follows: ; in, , Let be the voltages of nodes j and i during time period t, respectively. and These are the line impedance parameters; and These represent the active and reactive power flows from node i to node j, respectively.

[0007] Furthermore, the formula for calculating the voltage sensitivity of each zone is as follows: ; in, The voltage sensitivity of partition z; The voltage of the weakest node during time period t; The equivalent injected active power for partition z in time period t.

[0008] Furthermore, the aggregate power of the zoned electric vehicles is expressed as: ; The net power of a zone is expressed as: ; The total photovoltaic output of the zone is expressed as follows: ; in, For the set of EVs within the partition; For partitioning During the period EV aggregate active power; For EV individuals During the period The active power of charging and discharging; For partitioning During the period Net power requirement / net load; For partitioning During the period The aggregated active power load includes conventional loads such as agriculture and residential loads; partition During the period Photovoltaic polymerization has active power output; For nodes / photovoltaic units During the period Those who have made meritorious contributions; Indicates partition Internal photovoltaic access point / photovoltaic unit collection.

[0009] Furthermore, the active power flow of node j satisfies ; Unreactive current satisfaction ; in, For time period branch road The positive current is in the direction of the branch road. ; For nodes The set of downstream child nodes, branch road During the period The meritorious trend, Represents a node The sum of active power transmitted to all its downstream branches; For nodes During the period Active load; For nodes During the period The photovoltaic system is generating active power. For nodes During the period EV aggregation is effective; For time period branch road The reactive power flow (kVar) above, in the same positive direction as above; branch road During the period The unproductive current; Represents a node The sum of reactive power transmitted to all downstream branches; For nodes During the period reactive load; For nodes During the period Photovoltaic reactive power; For nodes Photovoltaic inverters during time periods The controllable reactive power provided.

[0010] Furthermore, the process of generating the aggregated power adjustment range for electric vehicles in each zone takes the suppression of rural power grid voltage deviation, the suppression of power backflow from distribution transformers, and the constraint of excess power in each zone as comprehensive control objectives.

[0011] Furthermore, the aggregated power adjustment range of electric vehicles serves as a power constraint condition for the lower-level electric vehicle aggregation scheduling.

[0012] Furthermore, the lower-level electric vehicle aggregation scheduling aims to maximize economic benefits and penalizes behaviors that deviate from the aggregation power adjustment range.

[0013] Furthermore, in determining the aggregated charging and discharging power of the electric vehicle, the charging and discharging power of the electric vehicle is constrained by the rated charging and discharging power range; the state of charge of the electric vehicle is updated according to the charging and discharging power and is constrained by the minimum state of charge and the maximum state of charge, and the aggregated charging and discharging power of the electric vehicle within the zone is constrained by the upper limit of the station-level capacity.

[0014] A rural photovoltaic backfeed suppression and electric vehicle coordinated control system, the system comprising: The voltage sensitivity calculation module, based on the radial rural feeder topology, divides the rural power grid feeder into zones and calculates the voltage sensitivity of each zone. The control parameter generation module, based on the voltage sensitivity of the partition and with the upper-level rural power grid control center as the main body, constructs an objective function and determines the aggregate power adjustment range of electric vehicles and photovoltaic reactive power control parameters for each partition. The charging and discharging power determination module determines the aggregate charging and discharging power of the electric vehicle under the condition of satisfying the aggregate power adjustment range constraint. The rural power grid coordinated control module coordinates and controls the rural power grid feeders based on the photovoltaic reactive power control parameters and the aggregated charge and discharge power.

[0015] The technical solution of this invention can achieve the following technical effects: This invention addresses the problem of significant differences in voltage sensitivity among different feeder zones in the radial feeder structure of rural power distribution networks, making it difficult for a unified control method to effectively suppress photovoltaic backfeeding. By dividing the rural power grid feeders into zones and calculating the voltage sensitivity of each zone, the control strategy can reflect the voltage response characteristics of different zones to power changes, thus avoiding the lack of specificity in traditional overall control methods. Furthermore, based on the zoned voltage sensitivity, this invention introduces electric vehicles as an adjustable load resource, generating aggregated power adjustment ranges for electric vehicles in each zone. This is then coordinated with photovoltaic reactive power control parameters, allowing the charging and discharging behavior of electric vehicles to participate in photovoltaic backfeeding suppression according to the feeder operating status. This enables the local absorption of excess photovoltaic power, reducing the risk of power backfeeding from distribution transformers and feeders to the upper-level grid. In addition, by synergistically considering the aggregated charging and discharging power of electric vehicles and photovoltaic reactive power regulation, this invention implements coordinated control of the rural power grid feeders, improving feeder operating status without relying on photovoltaic power curtailment. This helps improve the rural power distribution network's ability to absorb distributed photovoltaic power and enhances the stability of the power distribution network's voltage operation.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating a method for coordinating the suppression of backflow from rural photovoltaic power grids with the control of electric vehicles. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Example 1: like Figure 1 As shown, this application provides a method for coordinating the suppression of backflow from rural photovoltaic power grids with the control of electric vehicles. The method includes: S1: Based on the radial rural feeder topology, the rural power grid feeder is divided into zones, and the voltage sensitivity of each zone is calculated. Specifically, starting from the distribution transformer, branch nodes are identified sequentially along the feeder trunk towards the end. Based on the feeder topology, branch connections, and line electrical characteristics, the entire rural power grid feeder is divided into several relatively independent zones. Each zone typically contains several nodes with similar electrical distances and operating characteristics, along with their connected loads and distributed photovoltaic units. Preferably, the zone division can comprehensively consider branch bifurcation locations, line lengths, conductor types, and historical voltage fluctuations to ensure consistent voltage responses to power changes within the same zone, thus avoiding the inclusion of nodes with significantly different electrical characteristics in the same area. After completing the feeder zoning, the impact of active power changes on the voltage levels of key feeder nodes within each zone is analyzed to obtain corresponding voltage sensitivity parameters. These parameters characterize the strength of voltage responses to power injection or absorption changes in different zones. This voltage sensitivity is not simply determined based on node geographical location but reflects the zone's comprehensive ability to respond to voltage changes under actual grid operating conditions. For example, zones farther from the distribution transformer and with higher line impedance typically exhibit more significant voltage responses to power changes. The process of zoning and obtaining voltage sensitivity provides a foundation for implementing differentiated control for different zones, enabling control strategies to focus on voltage-weak areas in rural power distribution networks, thereby improving the overall targeting and effectiveness of control.

[0022] S2: Based on the voltage sensitivity of the zones, with the upper-level rural power grid control center as the main body, construct the objective function and determine the aggregate power adjustment range of electric vehicles and photovoltaic reactive power control parameters for each zone; Specifically, after completing the rural power grid feeder zoning and obtaining the voltage sensitivity parameters of each zone, the upper-level rural power grid control center uniformly executes control decisions. Using zone voltage sensitivity as the core basis for reflecting the response characteristics of different zones to voltage changes, a comprehensive control target is constructed to guide operation control. Based on this, the aggregate power adjustment range of electric vehicles and photovoltaic reactive power control parameters for each zone are determined. In a preferred embodiment, the upper-level rural power grid control center comprehensively considers voltage deviation, backfeed risks of distribution transformers and feeders during rural power grid operation, and the sensitivity of different zones to power changes. Zone voltage sensitivity is incorporated into the control decision-making process, giving zones more sensitive to voltage changes higher weight in control. Based on the above control targets, the upper-level rural power grid control center generates an adjustable range for the aggregate power of electric vehicles for each zone, limiting the power boundary that electric vehicles in that zone can participate in adjustment during the current operating cycle. Simultaneously, corresponding reactive power adjustment parameters are configured for the photovoltaic inverters connected to that zone, making the photovoltaic reactive power adjustment capability complementary to the electric vehicle power adjustment. Preferably, for zones with higher voltage sensitivity and a greater risk of voltage overshoot or backfeed, the electric vehicle aggregate power adjustment range is set relatively wide to enhance the zone's ability to absorb excess photovoltaic power and simultaneously increase the participation of photovoltaic reactive power regulation. Conversely, for zones with lower voltage sensitivity, the adjustment range is narrowed accordingly to avoid unnecessary impacts on the operating status of other zones due to excessive regulation. Through this method, the upper-level rural power grid control center achieves the generation of control parameters based on zone differences without relying on uniform power limiting or a single regulation method, providing clear and executable adjustment boundaries for subsequent coordinated control.

[0023] S3: Determine the aggregate charging and discharging power of the electric vehicle under the condition of satisfying the aggregate power adjustment range constraint; Specifically, after the upper-level rural power grid control center has generated an electric vehicle aggregated power adjustment range for each zone, the electric vehicle aggregated scheduling unit determines the aggregated charging and discharging power of the corresponding zone within the current operating cycle, within the constraints of the adjustment range. In a preferred embodiment, the electric vehicle aggregated scheduling unit takes the zone as the basic control object, collects the operating information of multiple electric vehicles connected to the zone, and coordinates and allocates the charging and discharging behavior of each electric vehicle without exceeding the aggregated power adjustment range given by the upper level, thereby forming the aggregated charging and discharging power at the zone level. Preferably, when determining the aggregated charging and discharging power, the number of electric vehicles connected to the zone, the available charging and discharging capacity, and the current operating status can be comprehensively considered, so that the determined aggregated power not only meets the upper-level control requirements but also has practical feasibility. For example, when the photovoltaic output is high and the upper-level control center sets a large charging adjustment range for the zone, the electric vehicle aggregation scheduling unit can guide more vehicles in the charging state to participate in charging, thereby improving the zone's ability to absorb excess photovoltaic power. When the upper-level control center limits a narrow adjustment range for a certain zone, it can coordinate to reduce the number of vehicles participating in the adjustment or reduce the charging and discharging level of a single vehicle, so that the aggregated power is always kept within the allowable range.

[0024] S4: Based on photovoltaic reactive power control parameters and aggregated charging and discharging power, the rural power grid feeder is coordinated and regulated.

[0025] Specifically, after obtaining the photovoltaic reactive power control parameters of each zone and the aggregate charging and discharging power of electric vehicles, these two types of control quantities are used as coordinated control measures in the operation control process of the rural power grid feeder to achieve comprehensive regulation of photovoltaic backfeeding and voltage status. In a preferred embodiment, the upper-level rural power grid control center sends the photovoltaic reactive power control parameters to the photovoltaic inverters in the corresponding zones, enabling them to participate in voltage regulation according to the preset reactive power regulation mode. At the same time, the determined aggregate charging and discharging power of electric vehicles is introduced into the feeder operation as a load-side regulation quantity, thereby forming a synergistic effect between the generation side and the load side. Through this coordinated control method, when the photovoltaic output in a certain zone is high and there is a risk of backfeeding, on the one hand, the reactive power regulation of the photovoltaic inverter is used to smooth the local voltage level, and on the other hand, the excess active power is absorbed by the electric vehicle aggregation charging, reducing the possibility of backfeeding to the upper-level grid from the source. In operating scenarios with small voltage fluctuations or low backfeeding risks, the control intensity is reduced accordingly to avoid unnecessary impact on the normal operation of other zones. The above-mentioned coordinated control process is dynamically executed based on the feeder operating status, so that the photovoltaic reactive power regulation and the electric vehicle aggregation power regulation cooperate with each other under the same control framework. Thus, without relying on a single control method, the stable control of the rural power grid feeder operating status is achieved, improving the adaptability of the rural distribution network to distributed photovoltaics.

[0026] The technical solution of this invention effectively solves the problem that it is difficult to suppress photovoltaic backfeeding under unified control due to the difference in voltage sensitivity of different zones in rural radial feeder structures. By coordinating the regulation of photovoltaic reactive power and the aggregated charging and discharging behavior of electric vehicles, the invention achieves coordinated control of photovoltaic backfeeding suppression and rural power grid operation status.

[0027] As a preferred embodiment of the above, the voltage sensitivity adopts a linearized DistFlow model, which is expressed as follows: ; in, , Let be the voltages of nodes j and i during time period t, respectively. and These are the line impedance parameters; and These represent the active and reactive power flows from node i to node j, respectively.

[0028] As a preferred embodiment of the above, the formula for calculating the voltage sensitivity of each zone is as follows: ; in, The voltage sensitivity of partition z; The voltage of the weakest node during time period t; The equivalent injected active power for partition z in time period t.

[0029] Specifically, based on the linearized DistFlow model describing the voltage and power flow relationship of rural power grid feeder nodes, the voltage sensitivity parameters for each zone are obtained by analyzing the impact of changes in equivalent active power in different zones on the voltage level of the weakest node in the feeder. First, based on the topology and line parameters of the rural radial feeder, the voltage state of each node in the feeder is estimated at different operating times using the linearized DistFlow model, thereby identifying the node with the lowest voltage level or the most significant voltage fluctuation under the current operating conditions as the weakest node in that period. Then, the photovoltaic output, load, and adjustable resources within the zone are comprehensively equivalent to the active power injection of the zone. By analyzing the voltage change trend of the weakest node when the equivalent active power of the zone changes, the voltage sensitivity of the corresponding zone is calculated. Preferably, this voltage sensitivity is used to quantitatively reflect the strength of the impact of power changes in a zone on the feeder's operating state, enabling different zones to be treated differently according to their degree of voltage impact in subsequent regulation. For example, in a zone located at the end of a feeder with high line impedance, the voltage response amplitude at the weakest node is usually large when its equivalent active power changes. The above calculation method yields a high voltage sensitivity value, indicating that this zone requires close attention during operation and control. Conversely, zones closer to distribution transformers with better line conditions exhibit relatively lower voltage sensitivity and greater resilience to power changes. This method, while ensuring the calculation process conforms to the physical characteristics of the distribution network, achieves a quantitative characterization of the voltage impact characteristics of different feeder zones, providing a reliable basis for subsequent control decisions based on zone differences.

[0030] As a preferred embodiment of the above, the aggregate power of the zoned electric vehicles is expressed as: ; The net power of a zone is expressed as: ; The total photovoltaic output of the zone is expressed as follows: ; in, For the set of EVs within the partition; For partitioning During the period EV aggregate active power; For EV individuals During the period The active power of charging and discharging; For partitioning During the period Net power requirement / net load; For partitioning During the period The aggregated active power load includes conventional loads such as agriculture and residential loads; partition During the period Photovoltaic polymerization has active power output; For nodes / photovoltaic units During the period Those who have made meritorious contributions; Indicates partition Internal photovoltaic access point / photovoltaic unit collection.

[0031] Specifically, firstly, multiple electric vehicles connected to the same zone are considered as a uniformly controllable load set. By summing the charging and discharging power of each electric vehicle in the zone during the corresponding time period, the aggregated active power of electric vehicles in that zone is obtained, which characterizes the overall power regulation capability of electric vehicles at the zone level. At the same time, the active power output of multiple photovoltaic units connected to the zone is aggregated to form the total photovoltaic output of the zone, reflecting the distributed photovoltaic power generation level of the zone in the current time period. Based on this, combined with the conventional electricity demand such as agricultural load and residential load in the zone, the aggregated power of electric vehicles, the aggregated output of photovoltaics, and the conventional load of the zone are uniformly balanced to obtain the net power of the zone, which is used to characterize the net load or net power injection state of the zone in the current operating period. Preferably, when the photovoltaic output in the zone is high and the aggregated charging power of electric vehicles is large, the net power of the zone can be represented as a load state, which is conducive to absorbing local photovoltaic power. When the participation of electric vehicles is low or the photovoltaic output decreases, the net power of the zone increases accordingly, reflecting the change in power demand from the upper-level grid. By using the aforementioned power aggregation and net power characterization methods at the partition level, the dispersed electric vehicles and photovoltaic units within a partition are uniformly mapped into equivalent power quantities that can be used for control decisions. This enables the rural power grid operation status to be clearly and intuitively described at the partition scale, providing a foundation for subsequent control based on partition power characteristics.

[0032] As a preferred embodiment of the above embodiments, the active power flow of node j satisfies ; Unreactive current satisfaction ; in, For time period branch road The positive current is in the direction of the branch road. ; For nodes The set of downstream child nodes, branch road During the period The meritorious trend, Represents a node The sum of active power transmitted to all its downstream branches; For nodes During the period Active load; For nodes During the period The photovoltaic system is generating active power. For nodes During the period EV aggregation is effective; For time period branch road The reactive power flow (kVar) above, in the same positive direction as above; branch road During the period The unproductive current; Represents a node The sum of reactive power transmitted to all downstream branches; For nodes During the period reactive load; For nodes During the period Photovoltaic reactive power; For nodes Photovoltaic inverters during time periods The controllable reactive power provided.

[0033] Specifically, when analyzing and regulating the operation status of rural power grid feeders, a radial feeder structure is used as the basis for unified modeling of the active and reactive power flows at each node to reflect the power balance at the node. In a preferred embodiment, any node in the feeder is considered a key location for power aggregation and distribution. The active and reactive power transmitted to this node from its upstream branches is used to meet the node's own load demand, distributed photovoltaic power generation output, aggregated charging and discharging power of electric vehicles, and the power continued to be transmitted to downstream branches. Specifically, the active power flow of a node is jointly determined by the active power demand of each downstream branch, the conventional load at the node, the aggregated active power of electric vehicles, and the active power output of photovoltaics, thus reflecting the comprehensive impact of electric vehicles and photovoltaic access on the active power balance of the node; the reactive power flow of a node, based on the reactive power demand and conventional reactive load of the downstream of the node, introduces the controllable reactive power of the photovoltaic inverter, so that the reactive power balance of the node can be compensated through inverter adjustment. In practical operation scenarios, when the photovoltaic output at a node is high, the photovoltaic inverter can participate in the node's reactive power balance by adjusting its reactive power output, thereby mitigating voltage fluctuations. Simultaneously, the aggregated charging behavior of electric vehicles at a node alters the node's active power demand level, impacting the active power flow of upstream branches. For example, at the end node of a feeder, if photovoltaic units and multiple electric vehicles are simultaneously connected, the aforementioned active and reactive power flow balance relationship can clearly characterize the interaction between photovoltaic power generation, electric vehicle loads, and conventional loads, providing a basis for judging the node's operating status and its impact on the overall power distribution of the feeder. By adopting the above node power balance modeling method, the rural power grid feeder, even with the introduction of electric vehicles and distributed photovoltaics, can still have its active and reactive power flow characteristics described in a clear and interpretable manner, providing necessary operational status support for subsequent control decisions.

[0034] As a preferred embodiment of the above, the process of generating the aggregated power adjustment range of electric vehicles in each zone takes the suppression of rural power grid voltage deviation, the suppression of power backflow from distribution transformers, and the constraint of excess power in each zone as the comprehensive control objectives.

[0035] Specifically, the objective function for optimizing the aggregate power adjustment range of an electric vehicle is: ,in, For nodes During the period The voltage amplitude; The reference voltage (usually taken as) pu), used for voltage deviation penalty items; The positive part of the backfeed quantity is equivalent to "only penalizing backfeeding, not penalizing normal power receiving"; This is a voltage deviation penalty weight (used to balance terms with different dimensions, usually treated as a dimensionless weight). To transfer penalty weights; The weighting of excess photovoltaics in the partition is used for penalties.

[0036] Backfeed power is defined as: in, For time period Net active power exchange (kW) at the distribution transformer (transformer in the distribution area / grid connection point); Active power supplied from the upper-level power grid to the distribution area / transformer; For the merit of the transformer area in feeding back to the superior power grid, when This indicates that the distribution transformer is moving against the current and needs to be penalized.

[0037] The definition of excess photovoltaic power in a zone is: Therefore, the upper output power range , This indicates the adjustable EV power range (kW) output from the upper layer to the lower layer. After satisfying voltage / power flow constraints, the upper layer provides the allowable aggregate charge / discharge range for that region during that time period. As a preferred embodiment of the above, the aggregated power adjustment range of electric vehicles serves as the power constraint condition for the lower-level electric vehicle aggregated scheduling.

[0038] Specifically, the reason for using the aggregated power adjustment range of electric vehicles as the power constraint condition for lower-level electric vehicle aggregation scheduling is that the upper-level rural power grid control center and the lower-level electric vehicle scheduling differ in their functional focus and information scope. The upper-level rural power grid control center mainly focuses on the overall operating status of the distribution network, including network-level constraints such as voltage deviation, backfeed risk of distribution transformers, and regional power balance, rather than directly grasping detailed information such as the access status, state of charge, and user demand of individual electric vehicles. Correspondingly, the lower-level electric vehicle aggregation scheduling unit is more suitable for allocating specific charging and discharging power based on real-time vehicle operating information. By generating the aggregated power adjustment range of electric vehicles from the upper-level control center and using this range as the power constraint condition for lower-level scheduling, the lower-level scheduling results are always limited to the range that meets the safety requirements of rural power grid operation. At the same time, it allows the lower level to flexibly schedule according to the actual vehicle status within the range, thereby improving the executability and adaptability of the control scheme while prioritizing voltage stability and backfeed suppression, and achieving effective coordination between upper and lower-level control.

[0039] As a preferred embodiment of the above, the lower-level electric vehicle aggregation scheduling aims to maximize economic benefits and penalizes behaviors that deviate from the aggregation power adjustment range.

[0040] Specifically, the objective function for lower-level electric vehicle aggregation scheduling is as follows: The first item represents the profit from electricity price arbitrage. For time period The equivalent electricity price coefficient is used to characterize the arbitrage profit level per unit of electricity during this period, also known as the equivalent price difference or unit profit coefficient. Its value is determined by the market electricity price / time-of-use electricity price, etc. For time period Electricity sold to the user side (EV side) (kWh); For time period Electricity purchased from the grid; Indicates time period The first term represents the profit from electricity price arbitrage. The second term represents the incentive profit obtained in response to instructions from higher levels. For upper-level partitioning During the period Incentive unit price / subsidy standard; For partitioning During the period The amount of service that can be incentivized for settlement. Calculated according to the settlement criteria stipulated by the higher level, the effective service volume related to absorbing excess photovoltaic power can be taken. The third item represents the deviation penalty, which encourages the lower level to execute the plan of the higher level as much as possible; For deviation penalty coefficient; This is the reference aggregate power given by the upper layer to the lower layer, representing the expected execution value; This is the deviation amount. .

[0041] As a preferred embodiment of the above, in the process of determining the aggregate charging and discharging power of the electric vehicle, the charging and discharging power of the electric vehicle is constrained by the rated charging and discharging power range; the state of charge of the electric vehicle is updated according to the charging and discharging power and is constrained by the minimum state of charge and the maximum state of charge, and the aggregate charging and discharging power of the electric vehicle within the zone is constrained by the upper limit of the station-level capacity.

[0042] Specifically, EV charging and discharging power ,in, For EV individuals The maximum charge and discharge power amplitude.

[0043] SOC Evolution: ,in, For EV individuals During the period The state of charge; The charge / discharge efficiency coefficient; The time step is in hours (h).

[0044] SOC range: ,in, Individual EVs The lower and upper limits of SOC.

[0045] Station-level capacity limit: ,in, For partitioning The station-level / aggregate capacity limit reflects the transformer capacity, pile power, or grid-connected capacity of the charging station. The above formula means that the sum of the power amplitude of all EVs in the zone shall not exceed the station-level capacity.

[0046] To achieve real-time performance and robustness, this invention adopts the following update method: ,in, For the upper level during the time period For partitions Provide the reference power command to the lower layer; To update the step size / relaxation coefficient (0-1), used to balance convergence speed and stability, if the lower-level execution power is higher than the reference ( If the reference value is lowered in the next cycle, it will be lowered; otherwise, it will be raised, so that the upper and lower layers gradually become consistent and suppress oscillations.

[0047] Example 2: Based on the same inventive concept as the method for suppressing backflow of rural photovoltaic power and coordinating control of electric vehicles in the foregoing embodiments, the present invention also provides a control system for suppressing backflow of rural photovoltaic power and coordinating control of electric vehicles, comprising: The voltage sensitivity calculation module, based on the radial rural feeder topology, divides the rural power grid feeder into zones and calculates the voltage sensitivity of each zone. The control parameter generation module, based on the voltage sensitivity of the zones and with the upper-level rural power grid control center as the main body, constructs an objective function and determines the aggregate power adjustment range of electric vehicles and photovoltaic reactive power control parameters for each zone. The charging and discharging power determination module determines the aggregate charging and discharging power of the electric vehicle under the condition of satisfying the aggregate power adjustment range constraint. The rural power grid coordinated control module coordinates and controls the rural power grid feeders based on photovoltaic reactive power control parameters and aggregated charging and discharging power.

[0048] The control system described above in this invention can effectively realize the method of suppressing backfeeding of rural photovoltaic power grids and coordinating control of electric vehicles. The technical effects it can achieve are as described in the above embodiments, and will not be repeated here.

[0049] Similarly, the above-mentioned optimization schemes for the system can also achieve the optimization effects corresponding to the methods in Embodiment 1, which will not be repeated here.

[0050] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A method for suppressing backflow of photovoltaic power in rural power grids and coordinating control of electric vehicles, characterized in that, The method includes: Based on the radial rural feeder topology, the rural power grid feeder is divided into zones, and the voltage sensitivity of each zone is calculated. Based on the voltage sensitivity of the zones, and taking the upper-level rural power grid control center as the main body, an objective function is constructed, and the aggregate power adjustment range of electric vehicles and photovoltaic reactive power control parameters of each zone are determined. Under the condition of satisfying the aforementioned aggregate power adjustment range constraint, determine the aggregate charging and discharging power of the electric vehicle; Based on the photovoltaic reactive power control parameters and the aggregated charging and discharging power, the rural power grid feeder is synergistically regulated.

2. The method for suppressing backflow of rural photovoltaic power and coordinating control of electric vehicles according to claim 1, characterized in that, Voltage sensitivity is assessed using a linearized DistFlow model, which is expressed as follows: ； in, , Let be the voltages of nodes j and i during time period t, respectively. and These are the line impedance parameters; and These represent the active and reactive power flows from node i to node j, respectively.

3. The method for suppressing backflow of rural photovoltaic power and coordinating control of electric vehicles according to claim 2, characterized in that, The formula for calculating the voltage sensitivity of each zone is as follows: ； in, The voltage sensitivity of partition z; The voltage of the weakest node during time period t; The equivalent injected active power for partition z in time period t.

4. The method for suppressing backflow of rural photovoltaic power and coordinating control of electric vehicles according to claim 1, characterized in that, The aggregate power of electric vehicles in a given area is expressed as: ； The net power of a zone is expressed as: ; The total photovoltaic output of the zone is expressed as follows: ; in, For the set of EVs within the partition; For partitioning During the period EV aggregate active power; For EV individuals During the period The active power of charging and discharging; For partitioning During the period Net power requirement / net load; For partitioning During the period The aggregated active power load includes conventional loads such as agriculture and residential loads; partition During the period Photovoltaic polymerization has active power output; For nodes / photovoltaic units During the period Those who have made meritorious contributions; Indicates partition Internal photovoltaic access point / photovoltaic unit collection.

5. The method for suppressing backflow of rural photovoltaic power and coordinating control of electric vehicles according to claim 1, characterized in that, The active power flow of node j satisfies ; Unreactive current satisfaction ; in, For time period branch road The positive current direction is according to the branch direction. ; For nodes The set of downstream child nodes, branch road During the period The meritorious trend, Represents a node The sum of active power transmitted to all its downstream branches; For nodes During the period Active load; For nodes During the period The photovoltaic system is generating active power. For nodes During the period EV aggregation is effective; For time period branch road The reactive power flow (kVar) above, in the same positive direction as above; branch road During the period The unproductive current; Represents a node The sum of reactive power transmitted to all downstream branches; For nodes During the period reactive load; For nodes During the period Photovoltaic reactive power; For nodes Photovoltaic inverters during time periods The controllable reactive power provided.

6. The method for suppressing backflow of rural photovoltaic power and coordinating control of electric vehicles according to claim 1, characterized in that, The process of generating the aggregated power adjustment range of electric vehicles in each zone takes the suppression of rural power grid voltage deviation, the suppression of power backflow from distribution transformers, and the constraint of excess power in each zone as the comprehensive control objectives.

7. The method for suppressing backflow of rural photovoltaic power and coordinating control of electric vehicles according to claim 1, characterized in that, The aggregated power adjustment range of electric vehicles serves as a power constraint for the aggregated scheduling of lower-level electric vehicles.

8. The method for suppressing backflow of rural photovoltaic power and coordinating control of electric vehicles according to claim 1, characterized in that, The lower-level electric vehicle aggregation scheduling aims to maximize economic benefits and penalizes behaviors that deviate from the aggregation power adjustment range.

9. The method for suppressing backflow of rural photovoltaic power and coordinating control of electric vehicles according to claim 1, characterized in that, In determining the aggregate charging and discharging power of electric vehicles, the charging and discharging power of electric vehicles is constrained by the rated charging and discharging power range; the state of charge of electric vehicles is updated according to the charging and discharging power and is constrained by the minimum state of charge and the maximum state of charge, and the aggregate charging and discharging power of electric vehicles within a zone is constrained by the upper limit of the station-level capacity.

10. A rural photovoltaic backfeed suppression and electric vehicle coordinated control system, characterized in that, The system includes: The voltage sensitivity calculation module, based on the radial rural feeder topology, divides the rural power grid feeder into zones and calculates the voltage sensitivity of each zone. The control parameter generation module, based on the voltage sensitivity of the partition and with the upper-level rural power grid control center as the main body, constructs an objective function and determines the aggregate power adjustment range of electric vehicles and photovoltaic reactive power control parameters for each partition. The charging and discharging power determination module determines the aggregate charging and discharging power of the electric vehicle under the condition of satisfying the aggregate power adjustment range constraint. The rural power grid coordinated control module coordinates and controls the rural power grid feeders based on the photovoltaic reactive power control parameters and the aggregated charge and discharge power.

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