Active power distribution network overvoltage control system and method

Abstract

This application provides an active distribution network overvoltage control system and method. The active distribution network overvoltage control system includes several local controllers and a coordination controller; the several local controllers are used to collect photovoltaic inverter information and send active power regulation commands and reactive power regulation commands to the corresponding photovoltaic inverters; the coordination controller is connected to the several local controllers and is used to receive photovoltaic inverter information, obtain several transformer area voltages and multiple feeder voltages, and send active power regulation commands and reactive power regulation commands based on the several transformer area voltages and multiple feeder voltages; the control method includes determining whether any one of the multiple feeders, several transformer areas, or several grid connection points is overvoltaged; in the case of overvoltage at any one of the multiple feeders, several transformer areas, or several grid connection points, voltage regulation control is performed on the system according to the reactive power regulation coefficient and the active power regulation coefficient.

Description

Technical Field

[0001] This application relates to the field of power system control, and more specifically, to an active distribution network overvoltage control system and method. Background Technology

[0002] Connecting a large number of distributed power sources to a distribution network may lead to operational issues such as reverse power flow, which in turn raises the voltage at the grid connection point, transformer substations, and feeders. Overvoltage can cause distributed power sources to trip, jeopardizing operational safety. Therefore, overvoltage control technology is needed to address these issues.

[0003] The paper "Distributed Voltage Control in Distribution Networks with High-Penetration Photovoltaics" proposes a distributed voltage control strategy for distribution networks, achieving low-cost and rapid voltage control through reactive power coordination compensation and active power optimization reduction of the photovoltaic system. The paper "Local-Distributed Voltage Control in Distribution Networks with High-Penetration Photovoltaics" proposes a voltage control strategy for distribution networks with high-penetration photovoltaics based on the approximate voltage sensitivity of distribution network nodes and combining the characteristics of local control and distributed control. This strategy utilizes local measurement data and distributed communication information to achieve economical and rapid voltage control of the system through reactive power coordination control and active power optimization scheduling of key nodes.

[0004] Patent CN114421474B, "Estimation Method for Power-Voltage Sensitivity Between Distribution Network Nodes," proposes a method for estimating the power-voltage sensitivity between distribution network nodes. This method selects a number of nodes in the distribution network that is much smaller than the total number of nodes in the network. This avoids reliance on the distribution network topology and network equipment parameters, as well as the requirement to monitor all nodes in the network. It can also proactively adapt to the dynamic changes in the distribution network, effectively meeting the power-voltage control and evaluation needs of the distribution network. Patent CN114552593A, "An Evaluation Method for Reactive Power and Voltage Adjustment Elasticity Margin of Power Grid," proposes a method for evaluating the reactive power and voltage adjustment elasticity margin of power grid. This method quantifies and evaluates the adjustable reactive power and voltage resources in the power source, grid, load, and storage, and ultimately provides multiple classification margin indicators, overall system margin indicators, and level classifications. It aims to accurately quantify the elasticity margin of the adjustable reactive power and voltage resources of the power grid, providing a reliable and powerful reference for the optimal planning and control of the power grid and reactive power and voltage.

[0005] However, the above methods lack comprehensive consideration of complex overvoltage situations in multi-layered distribution network structures, and the control methods do not take into account voltage control sensitivity and adjustability margin.

[0006] Therefore, it is necessary to propose an active distribution network overvoltage control method and system based on voltage sensitivity and active and reactive power adjustable margin, which takes into account both control cost and control speed, and can minimize inverter control cost under the condition of rapidly suppressing overvoltage.

[0007] The information disclosed in the background section is only intended to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0008] This application aims to provide an active distribution network overvoltage control system and method based on voltage sensitivity and active and reactive power adjustable margin, which takes into account both control cost and control speed, and can minimize inverter control cost under the condition of rapidly suppressing overvoltage.

[0009] According to one aspect of this application, an active distribution network overvoltage control system is proposed, the control system comprising a plurality of photovoltaic inverters, a plurality of grid connection points, a plurality of transformer substations, a plurality of feeders, a plurality of local controllers and a coordination controller, wherein:

[0010] Any one of the plurality of feeders connects to a plurality of the plurality of transformer substations, any one of the plurality of transformer substations connects to a plurality of the plurality of grid connection points, and any one of the plurality of grid connection points connects to a plurality of the plurality of photovoltaic inverters.

[0011] The plurality of local controllers are connected one-to-one with the plurality of photovoltaic inverters, and are used to collect photovoltaic inverter information and send active power adjustment commands and reactive power adjustment commands to the corresponding photovoltaic inverters. The photovoltaic inverter information includes grid connection point voltage, output active power, output reactive power, adjustable active power and adjustable reactive power.

[0012] The coordination controller is connected to the plurality of local controllers, and is used to receive photovoltaic inverter information, connect to the plurality of feeders, obtain the plurality of transformer area voltages and the plurality of feeder voltages, and send the active power regulation command and the reactive power regulation command based on the plurality of transformer area voltages and the plurality of feeder voltages.

[0013] According to some embodiments, the local controller communicates with the coordinating controller via optical fiber or wireless communication, sends information about the photovoltaic inverter, and receives the active power regulation command and the reactive power regulation command.

[0014] According to a second aspect of this application, an active distribution network overvoltage control method is proposed for use in an active distribution network overvoltage control system as described in any one of the first aspects, comprising:

[0015] Determine whether any one of the plurality of feeders, the plurality of transformer substations, or the plurality of grid connection points is overvoltage;

[0016] In the event of overvoltage in any of the plurality of feeders, the plurality of transformer substations, or the plurality of grid connection points, the reactive power of the control system is controlled according to the reactive power regulation coefficient.

[0017] According to some embodiments, in the event of an overvoltage in any of the plurality of feeders, the plurality of transformer substations, or the plurality of grid connection points, controlling the reactive power of the control system according to the reactive power regulation coefficient includes:

[0018] In the event of overvoltage in the feeder, the reactive power of the feeder is controlled in ascending order of the reactive voltage regulation coefficient of the feeder.

[0019] For the transformer substations connected to the feeder, the reactive power of the substations is controlled in ascending order of the reactive voltage regulation coefficient.

[0020] According to some embodiments, it also includes:

[0021] When the reactive power regulation coefficients of the transformer substations are the same, the reactive power of the transformer substations is controlled sequentially from the nearest to the farthest from the feeder.

[0022] According to some embodiments, the reactive power regulation coefficient of the feeder is:

[0023]

[0024] The reactive power regulation coefficient for the transformer area is:

[0025]

[0026] Among them, H Q_l J is the reactive power regulation coefficient for the transformer area. Q_m U is the reactive power regulation coefficient of the feeder. N The reference voltage point voltage, This is the sum of the line inductances from the reference voltage point to the overvoltage zone. This is the sum of the line inductances from the reference voltage point to the overvoltage feeder. This is the sum of the adjustable reactive power of the photovoltaic system under the transformer substation. Let Q be the sum of the adjustable reactive power of the photovoltaic system on feeder m, and sign(Q) be the sign function of Q, which is positive when inductive reactive power is generated and negative when capacitive reactive power is generated.

[0027] According to some embodiments, when the reactive power of the feeder reaches the adjustable reactive power and there is feeder overvoltage, the active power of the feeder is controlled in ascending order of the feeder active voltage adjustment coefficient.

[0028] For the transformer substations connected to the feeder, the active power of the substations is controlled in ascending order of the active voltage regulation coefficient of the substations.

[0029] According to some embodiments, when the active voltage regulation coefficients of the transformer substations are the same, the active power of the transformer substations is controlled sequentially from the nearest to the farthest from the distance between the transformer substations and the feeder.

[0030] According to some embodiments, the active voltage regulation coefficient of the feeder is:

[0031]

[0032] The active voltage regulation coefficient of the transformer area is:

[0033]

[0034] Among them, H P_l J is the active voltage regulation coefficient of the transformer area. P_m This is the active power voltage regulation coefficient for the feeder. This is the sum of the line resistances from the reference voltage point to the overvoltage zone. This is the sum of the line resistances from the reference voltage point to the overvoltage feeder. This is the sum of the adjustable active power of the photovoltaic system under the transformer substation. This is the sum of the adjustable active power of the photovoltaic system under the feeder line.

[0035] According to some embodiments, in the event of an overvoltage in any of the plurality of feeders, the plurality of transformer substations, or the plurality of grid connection points, controlling the reactive power of the control system according to the reactive power regulation coefficient includes:

[0036] In the event of overvoltage in the transformer area, the reactive power of the transformer area is controlled in ascending order of reactive power voltage regulation coefficient.

[0037] For the grid connection point connected to the transformer substation, the reactive power of the grid connection point is controlled in ascending order of the reactive voltage regulation coefficient of the grid connection point.

[0038] According to some embodiments, it also includes:

[0039] When the reactive power regulation coefficients of the grid connection points are the same, the reactive power of the grid connection points is controlled sequentially from the nearest to the farthest from the grid connection point and the transformer area.

[0040] According to some embodiments, the reactive power regulation coefficient at the grid connection point is:

[0041]

[0042] Among them, K Q_k The reactive voltage regulation coefficient at the grid connection point. This is the sum of adjustable reactive power from photovoltaic systems at the grid connection point. This is the sum of the line inductance from the reference voltage point to the photovoltaic inverter.

[0043] According to some embodiments, it also includes:

[0044] When the reactive power of the transformer area reaches the adjustable reactive power and there is overvoltage in the transformer area, the active power of the transformer area is controlled in order of increasing active voltage regulation coefficient.

[0045] For the grid connection points connected to the transformer substation, the active power of the grid connection points is controlled in ascending order of the active power voltage regulation coefficient of the grid connection points.

[0046] According to some embodiments, it also includes:

[0047] When the active voltage regulation coefficients of the grid connection points are the same, the active power of the grid connection points is controlled sequentially from the nearest to the farthest from the grid connection point and the transformer area.

[0048] According to some embodiments, the active voltage regulation coefficient at the grid connection point is:

[0049]

[0050] Among them, K P_k The active voltage regulation coefficient at the grid connection point. This is the sum of the line resistances from the reference voltage point to the overvoltage grid connection point. This is the sum of the adjustable active power of photovoltaic power at the grid connection point.

[0051] According to some embodiments, in the event of an overvoltage in any of the plurality of feeders, the plurality of transformer substations, or the plurality of grid connection points, controlling the reactive power of the control system according to the reactive power regulation coefficient includes:

[0052] In the event of overvoltage at the grid connection point, the reactive power of the grid connection point is controlled in ascending order of the reactive voltage regulation coefficient at the grid connection point.

[0053] For the photovoltaic inverter connected to the grid connection point, the reactive power of the photovoltaic inverter is controlled in ascending order of the reactive voltage regulation coefficient of the photovoltaic inverter.

[0054] According to some embodiments, it also includes:

[0055] When the reactive power regulation coefficients of the photovoltaic inverters are the same, the reactive power of the photovoltaic inverters is controlled sequentially from the nearest to the farthest from the grid connection point.

[0056] According to some embodiments, the reactive power voltage regulation coefficient of the photovoltaic inverter is:

[0057]

[0058] Among them, K Q_k_i Q is the reactive power regulation coefficient of the photovoltaic inverter. ei For photovoltaic inverters with adjustable reactive power, This is the sum of the line inductance from the reference voltage point to the photovoltaic inverter.

[0059] According to some embodiments, it also includes:

[0060] When the reactive power at the grid connection point reaches the adjustable reactive power and there is an overvoltage at the grid connection point, the active power at the grid connection point is controlled in ascending order of the active voltage adjustment coefficient at the grid connection point.

[0061] For the photovoltaic inverter connected at the grid connection point, the active power of the photovoltaic inverter is controlled in ascending order of the active voltage regulation coefficient of the photovoltaic inverter.

[0062] According to some embodiments, it also includes:

[0063] When the active voltage regulation coefficients of the photovoltaic inverters are the same, the active power of the photovoltaic inverters is controlled sequentially from the nearest to the farthest from the grid connection point.

[0064] According to some embodiments, the active voltage regulation coefficient of the photovoltaic inverter is:

[0065]

[0066] Among them, K P_k_i P is the active voltage regulation coefficient of the photovoltaic inverter. ei For adjustable active power of photovoltaic inverters, This is the sum of the line resistances from the reference voltage point to the photovoltaic inverter.

[0067] According to some embodiments, it also includes:

[0068] If at least two types of overvoltage exist in the feeder, the transformer area, or the grid connection point, voltage regulation control shall be performed in the order of priority for handling feeder overvoltage, handling transformer area overvoltage, and handling grid connection point overvoltage.

[0069] According to some embodiments, it also includes:

[0070] The voltage difference value is obtained by subtracting the collected feeder voltage, transformer area voltage, or grid connection point voltage from the control target voltage;

[0071] The voltage difference is adjusted by the overall PI active power regulation to obtain the overall active power control target;

[0072] The individual active power adjustment command is obtained based on the overall active power control target.

[0073] According to some embodiments, the calculation method for the active power regulation command of the individual is as follows:

[0074]

[0075] Where ΔP is the total active power control target, P ei For adjustable active power, ΔP i The active power regulation command is given by the individual, and Y is the set of overvoltage feeders.

[0076] According to some embodiments, it also includes:

[0077] The voltage difference value is obtained by subtracting the collected feeder voltage, transformer area voltage, or grid connection point voltage from the control target voltage;

[0078] The voltage difference is processed by the overall PI reactive power regulation to obtain the overall reactive power control target;

[0079] The individual reactive power adjustment command is obtained based on the overall reactive power control target.

[0080] According to some embodiments, the method for calculating the reactive power adjustment command of the individual is as follows:

[0081]

[0082] Where ΔQ is the total reactive power control target, Q ei For adjustable reactive power, ΔQ i The active power regulation command is given by the individual, and Y is the set of overvoltage feeders.

[0083] This application provides an active distribution network overvoltage control system and method based on voltage sensitivity and active and reactive power adjustable margins, which balances control cost and control speed, and can minimize inverter control cost under the condition of rapidly suppressing overvoltage.

[0084] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0085] The above and other objects, features, and advantages of this application will become more apparent from the detailed description of exemplary embodiments with reference to the accompanying drawings. The drawings described below are merely some embodiments of this application and are not intended to limit the scope of this application.

[0086] Figure 1 A schematic diagram of an active distribution network overvoltage control system based on voltage sensitivity and active and reactive power adjustable margin is shown as an exemplary embodiment.

[0087] Figure 2 A block diagram illustrating an exemplary embodiment of a coordinated active and reactive power control method is shown.

[0088] Figure 3 A flowchart illustrating a grid connection point voltage control method of an exemplary embodiment is shown.

[0089] Figure 4 A flowchart of a transformer substation voltage control method of an exemplary embodiment is shown;

[0090] Figure 5 A flowchart illustrating a feeder voltage control method of an exemplary embodiment is shown.

[0091] Figure 6 A schematic diagram illustrating the overvoltage suppression effect of an exemplary embodiment is shown. Detailed Implementation

[0092] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0093] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. In these cases, well-known structures, methods, devices, implementations, materials, or operations will not be shown or described in detail.

[0094] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0095] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0096] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of exemplary embodiments, and the modules or processes in the drawings are not necessarily essential for implementing this application, and therefore cannot be used to limit the scope of protection of this application.

[0097] Figure 1 This diagram illustrates an exemplary embodiment of an active distribution network overvoltage control system based on voltage sensitivity and adjustable active and reactive power margins.

[0098] like Figure 1 As shown, the active distribution network overvoltage control system includes a local controller LC and a coordination controller CC. The coordination controller CC is connected to the local controller LC and receives information from the local controller LC, collecting data on the transformer substation and feeder voltages. When an overvoltage occurs in a transformer substation or feeder, the active power regulation command P for photovoltaic inverter i is calculated according to the coordination control algorithm. di and reactive power regulation command Q di The value is then sent to the local controller LC via communication to execute the photovoltaic inverter control, where the photovoltaic inverter i = 1, 2, 3, ..., n.

[0099] According to the example embodiment, the local controller LC is connected to the photovoltaic inverter i and is used to collect photovoltaic inverter information and send active power regulation commands P to the photovoltaic inverter i. di and reactive power regulation command Q di When an overvoltage occurs, the inverter is controlled for active and reactive power according to the control algorithm.

[0100] According to the example embodiment, the photovoltaic inverter information includes the inverter's output active power P i Output reactive power Q i Adjustable active power P ei Adjustable reactive power Q ei Grid connection point voltage U PVi information.

[0101] According to some embodiments, the local controller LC is installed near the photovoltaic inverter i, and the coordination controller CC is installed in the substation.

[0102] According to some embodiments, the local controller LC communicates with the coordinating controller CC via high-speed, low-latency fiber optic or wireless communication to send photovoltaic inverter information and receive regulation commands.

[0103] According to some embodiments, the control strategy is divided into three layers: grid connection point, transformer area, and feeder voltage control. Figure 2 A block diagram illustrating an exemplary embodiment of a coordinated active and reactive power control method is shown. According to some embodiments, the control algorithm includes a coordinated active and reactive power control method.

[0104] According to some embodiments, the coordinated active power control method is as follows: the difference between the actual voltage U and the control target voltage Uset is used to form ΔU. ΔU is fed into the PI controller to generate the total active power control target value ΔP. ΔP is then multiplied by a coefficient. The active power control increment value ΔP allocated to i is obtained. i Where i can represent photovoltaic, grid connection point, transformer area, or feeder, Y represents the set of overvoltage grid connection points, transformer areas, or feeders, and P ei For adjustable active power, the ratio is 1 if there is only one target.

[0105] According to the example embodiment, taking transformer area i as an example, if the transformer area experiences overvoltage, the difference between the actual voltage U of the transformer area and the control target voltage Uset of the transformer area is used to form ΔU. ΔU is fed into the PI controller to generate the total active power control target value ΔP. ΔP is then multiplied by a coefficient. The active power control increment value ΔP allocated to transformer area i is obtained. i P ei Y represents the adjustable active power of the substation area, and Y represents the overvoltage substation set.

[0106] According to some embodiments, the coordinated reactive power control method is as follows: the difference between the actual voltage U and the control target voltage Uset is used to form ΔU. ΔU is fed into the PI controller to generate the total reactive power control target value ΔQ. ΔQ is then multiplied by a coefficient. The reactive power control increment value ΔQ allocated to i is obtained. i Where i can represent photovoltaic, grid connection point, transformer area, or feeder, Y represents the set of overvoltage grid connection points, transformer areas, or feeders, and Q... ei For adjustable reactive power, the ratio is 1 if there is only one target.

[0107] According to some embodiments, taking feeder i as an example, if the feeder experiences overvoltage, the difference between the actual feeder voltage U and the target feeder voltage Uset is taken to form ΔU. ΔU is then fed into the PI controller to generate the total reactive power control target value ΔQ. ΔQ is multiplied by a coefficient. The reactive power control increment value ΔQ allocated to feeder i is obtained. i Q ei Y represents the adjustable reactive power of the feeder and the set of overvoltage feeders.

[0108] According to the example embodiment, the active power control increment value ΔP i That is, the active power regulation command P di Reactive power control increment ΔQ i That is, reactive power regulation command Q di .

[0109] Figure 3 A flowchart of a grid connection point voltage control method is shown as an exemplary embodiment.

[0110] According to some embodiments, the grid connection point voltage control method adopts the following steps:

[0111] S301, determine if there is an overvoltage connection point.

[0112] According to the example embodiment, the voltage at the grid connection point k is greater than the upper limit of the photovoltaic grid connection point voltage U. PVk >U PVlim If the grid connection point k is considered to be overvoltage, then the overvoltage grid connection point k belongs to the set of overvoltage grid connection points A, k∈A.

[0113] S302, sort the overvoltage grid connection points.

[0114] According to the example embodiment, based on the reactive power voltage regulation coefficient K at the grid connection point Q_k Control the reactive power of the grid connection point in ascending order.

[0115] S303 sorts the photovoltaic inverters.

[0116] According to the example embodiment, for photovoltaic inverter i connected at the overvoltage grid connection point k, the photovoltaic reactive power voltage regulation coefficient K is used. Q_k_i Control the reactive power of photovoltaic inverter i in ascending order.

[0117] According to some embodiments, if the photovoltaic reactive voltage regulation coefficients are the same, they are adjusted sequentially from the nearest to the farthest distance between the photovoltaic inverter i and the overvoltage grid connection point.

[0118] According to some implementation methods, if the reactive power of the photovoltaic system at the grid connection point reaches the adjustable reactive power Q... ei If the grid connection point k is still overvoltage, then the active voltage adjustment coefficient K at the grid connection point k shall apply. P_k Control the active power at grid connection point k in ascending order; for photovoltaic inverter i connected to grid connection point k, control the active power voltage regulation coefficient K. P_k_i The active power of photovoltaic inverter i is controlled in ascending order. If the photovoltaic active voltage regulation coefficients are the same, the active power of photovoltaic inverter i is adjusted in ascending order according to the distance from the overvoltage point.

[0119] Figure 4 A flowchart of a transformer substation voltage control method is shown as an exemplary embodiment.

[0120] According to some embodiments, the transformer area voltage control method employs the following steps:

[0121] S401, determine if there is an overpressure zone.

[0122] According to the example embodiment, the voltage of transformer area 1 is greater than the upper limit of transformer area voltage U. Tl >U Tlim If a transformer area l is considered to be overvoltage, then the overvoltage transformer area l belongs to the set of overvoltage transformer areas B, l∈B.

[0123] S402, sort the overpressure zones.

[0124] According to the example embodiment, based on the reactive power voltage regulation coefficient H of the transformer area Q_l The reactive power of the photovoltaic system in the control area is arranged from smallest to largest.

[0125] S403, sort the grid connection points.

[0126] According to the example embodiment, for the grid connection point k connected to transformer area l, the reactive power voltage adjustment coefficient K of the grid connection point is used. Q_k Control the reactive power of grid connection point k in ascending order.

[0127] According to some embodiments, if the reactive voltage regulation coefficients of the grid connection points are the same, they are adjusted sequentially from the nearest to the farthest distance between the grid connection point k and the overvoltage point.

[0128] According to some embodiments, if the reactive power of photovoltaic inverter i under all grid connection points k in all distribution areas l reaches the adjustable reactive power Q ei If overvoltage persists, adjust according to the active voltage regulation coefficient H of the transformer area. P_l The active power of the control area is arranged in ascending order; for the grid connection point k connected to area l, the active power voltage regulation coefficient K of the grid connection point is used. P_k Control the active power of the grid connection point in ascending order. If the active voltage regulation coefficients of the grid connection points are the same, then adjust them sequentially according to the distance of the grid connection point k from the overvoltage point from near to far.

[0129] Figure 5 A flowchart illustrating a feeder voltage control method of an exemplary embodiment is shown.

[0130] According to some embodiments, the feeder voltage control method employs the following steps:

[0131] S501, determine if there is an overvoltage feeder.

[0132] According to the example embodiment, the feeder m voltage is greater than the upper limit of the feeder voltage U. Lm >U LlimIf feeder m is considered to be overvoltage, then the overvoltage feeder m belongs to the set of overvoltage feeders C, m∈C.

[0133] S502, sort the overvoltage feeders.

[0134] According to the example embodiment, based on the reactive voltage regulation coefficient J of the feeder m Q_m Control the reactive power of the feeder photovoltaic system in ascending order of size.

[0135] S503 sorts the station areas.

[0136] According to the example embodiment, for the transformer substation l connected to feeder m, the reactive power voltage regulation coefficient H of the transformer substation is used. Q_l The reactive power of console area l is displayed in ascending order.

[0137] According to some embodiments, if the reactive voltage regulation coefficients of the transformer substations are the same, they are adjusted sequentially from the nearest to the farthest point from the overvoltage point.

[0138] According to some embodiments, if the reactive power of photovoltaic inverter i under all feeder m, substation l, and grid connection point k reaches the adjustable reactive power Q... ei If overvoltage persists, adjust according to the feeder active voltage regulation coefficient J. P_m Control the active power of the feeder in ascending order; for the transformer substation l connected to feeder m, adjust the active power regulation coefficient H according to the transformer substation's active power regulation coefficient. P_l The active power of the control area is adjusted in ascending order. If the active voltage adjustment coefficients of the control areas are the same, the adjustment is made sequentially from the nearest to the farthest point from the overvoltage point.

[0139] According to some embodiments, if multiple overvoltage conditions occur, voltage regulation is performed in the following order: photovoltaic feeder overvoltage, low-voltage side overvoltage in the distribution area, and grid connection point overvoltage.

[0140] According to some embodiments, the active power voltage regulation coefficients for photovoltaic systems, grid connection points, transformer substations, and feeders are defined as follows:

[0141]

[0142]

[0143]

[0144]

[0145] In the above formula, U N The reference voltage point voltage, P is the sum of the line resistances from the reference voltage point to the overvoltage grid connection point k, the overvoltage feeder l, and the overvoltage feeder m. ei For photovoltaic inverters, i.e., adjustable active power. Let K be the sum of the adjustable active power of photovoltaic power at the grid connection point k. The sum of the adjustable active power of the photovoltaic system under the L-type substation. This represents the sum of the adjustable active power of the photovoltaic system at feeder m.

[0146] According to some embodiments, the reactive power regulation coefficients for photovoltaic systems, grid connection points, transformer substations, and feeders are defined as follows:

[0147]

[0148]

[0149]

[0150]

[0151] In the above formula, U N The reference voltage point voltage, Q is the sum of the line inductances from the reference voltage point to the photovoltaic inverter. ei For photovoltaic inverters with adjustable reactive power, Let K be the sum of the adjustable reactive power of photovoltaic power at the grid connection point k. This is the sum of the adjustable reactive power of the photovoltaic system under the L-type transformer substation. Let Q be the sum of the adjustable reactive power of the photovoltaic system under feeder m, and sign(Q) be the sign function of Q, which is positive when the photovoltaic inverter i outputs inductive reactive power and negative when it outputs capacitive reactive power.

[0152] Figure 6 A schematic diagram illustrating the overvoltage suppression effect of an exemplary embodiment is shown.

[0153] Figure 6 To address the overvoltage suppression effect of the active distribution network overvoltage control system based on this application, this application provides an active distribution network overvoltage control system and method based on voltage sensitivity and active and reactive power adjustable margins, which can quickly suppress overvoltage while balancing control cost and control speed.

[0154] It should be clearly understood that this application describes how specific examples are formed and used, but this application is not limited to any details of these examples. Rather, based on the teachings of the disclosure of this application, these principles can be applied to many other embodiments.

[0155] Furthermore, it should be noted that the above figures are merely illustrative representations of the processes included in the method according to exemplary embodiments of this application, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0156] Exemplary embodiments of this application have been specifically shown and described above. It should be understood that this application is not limited to the detailed structures, arrangements, or implementation methods described herein; rather, this application is intended to cover various modifications and equivalent arrangements contained within the spirit and scope of the appended claims.

Claims

1. An active distribution network overvoltage control method, characterized in that, An overvoltage control system for an active power distribution network, the control system comprising a plurality of photovoltaic inverters, a plurality of grid connection points, a plurality of transformer substations, and a plurality of feeders, wherein any one of the plurality of feeders connects to a plurality of transformer substations, any one of the plurality of transformer substations connects to a plurality of grid connection points, and any one of the plurality of grid connection points connects to a plurality of photovoltaic inverters, the control method comprising: Determine whether any one of the plurality of feeders, the plurality of transformer substations, or the plurality of grid connection points is overvoltage; In the event of overvoltage in any of the plurality of feeders, the plurality of transformer substations, or the plurality of grid connection points, the reactive power of the control system is controlled according to the reactive power regulation coefficient, including: In the event of overvoltage in the feeder, the reactive power of the feeder is controlled in ascending order of the reactive voltage regulation coefficient of the feeder. For the transformer area connected to the feeder, the reactive power of the transformer area is controlled in ascending order of the reactive voltage regulation coefficient of the transformer area. The reactive power regulation coefficient of the feeder is: The reactive power regulation coefficient for the transformer area is: in, This is the reactive power regulation coefficient for the transformer area. Q is the reactive power regulation coefficient of the feeder. ei For adjustable reactive power, U N The reference voltage point voltage, This is the sum of the line inductances from the reference voltage point to the overvoltage zone. This is the sum of the line inductances from the reference voltage point to the overvoltage feeder. This is the sum of the adjustable reactive power of the photovoltaic system under the transformer substation. Let Q be the sum of the adjustable reactive power of the photovoltaic system on feeder m, and sign(Q) be the sign function of Q, which is positive when inductive reactive power is generated and negative when capacitive reactive power is generated.

2. The control method as described in claim 1, characterized in that, Also includes: When the reactive power regulation coefficients of the transformer substations are the same, the reactive power of the transformer substations is controlled sequentially from the nearest to the farthest from the feeder.

3. The control method as described in claim 1, characterized in that, Also includes: When the reactive power of the feeder reaches the adjustable reactive power and there is feeder overvoltage, the active power of the feeder is controlled in ascending order of the feeder active voltage adjustment coefficient. For the transformer substations connected to the feeder, the active power of the substations is controlled in ascending order of the active voltage regulation coefficient of the substations.

4. The control method as described in claim 3, characterized in that, Also includes: When the active voltage regulation coefficients of the transformer substations are the same, the active power of the transformer substations is controlled sequentially from the nearest to the farthest from the feeder.

5. The control method as described in claim 3, characterized in that, The active voltage regulation coefficient of the feeder is: The active voltage regulation coefficient of the transformer area is: in, This refers to the active voltage regulation coefficient of the transformer substation. This is the active power voltage regulation coefficient for the feeder. This is the sum of the line resistances from the reference voltage point to the overvoltage zone. This is the sum of the line resistances from the reference voltage point to the overvoltage feeder. This is the sum of the adjustable active power of the photovoltaic system under the transformer substation. This is the sum of the adjustable active power of the photovoltaic system under the feeder line.

6. The control method as described in claim 1, characterized in that, In the event of overvoltage in any of the plurality of feeders, the plurality of transformer substations, or the plurality of grid connection points, controlling the reactive power of the control system according to the reactive power regulation coefficient includes: In the event of overvoltage in the transformer area, the reactive power of the transformer area is controlled in ascending order of reactive power voltage regulation coefficient. For the grid connection point connected to the transformer substation, the reactive power of the grid connection point is controlled in ascending order of the reactive voltage regulation coefficient of the grid connection point.

7. The control method as described in claim 6, characterized in that, Also includes: When the reactive power regulation coefficients of the grid connection points are the same, the reactive power of the grid connection points is controlled sequentially from the nearest to the farthest from the grid connection point and the transformer area.

8. The control method as described in claim 7, characterized in that, The reactive power regulation coefficient at the grid connection point is: in, The reactive voltage regulation coefficient at the grid connection point. This is the sum of adjustable reactive power from photovoltaic systems at the grid connection point. This is the sum of the line inductance from the reference voltage point to the photovoltaic inverter.

9. The control method as described in claim 6, characterized in that, Also includes: When the reactive power of the transformer area reaches the adjustable reactive power and there is overvoltage in the transformer area, the active power of the transformer area is controlled in order of increasing active voltage regulation coefficient. For the grid connection points connected to the transformer substation, the active power of the grid connection points is controlled in ascending order of the active power voltage regulation coefficient of the grid connection points.

10. The control method as described in claim 9, characterized in that, Also includes: When the active voltage regulation coefficients of the grid connection points are the same, the active power of the grid connection points is controlled sequentially from the nearest to the farthest from the grid connection point and the transformer area.

11. The control method as described in claim 9, characterized in that, The active voltage regulation coefficient at the grid connection point is: in, The active voltage regulation coefficient at the grid connection point. This is the sum of the line resistances from the reference voltage point to the overvoltage grid connection point. This is the sum of the adjustable active power of photovoltaic power at the grid connection point.

12. The control method as described in claim 1, characterized in that, In the event of overvoltage in any of the plurality of feeders, the plurality of transformer substations, or the plurality of grid connection points, controlling the reactive power of the control system according to the reactive power regulation coefficient includes: In the event of overvoltage at the grid connection point, the reactive power of the grid connection point is controlled in ascending order of the reactive voltage regulation coefficient at the grid connection point. For the photovoltaic inverter connected to the grid connection point, the reactive power of the photovoltaic inverter is controlled in ascending order of the reactive voltage regulation coefficient of the photovoltaic inverter.

13. The control method as described in claim 12, characterized in that, Also includes: When the reactive power regulation coefficients of the photovoltaic inverters are the same, the reactive power of the photovoltaic inverters is controlled sequentially from the nearest to the farthest from the grid connection point.

14. The control method as described in claim 12, characterized in that, The reactive power regulation coefficient of the photovoltaic inverter is: in, Q is the reactive power regulation coefficient of the photovoltaic inverter. ei For photovoltaic inverters with adjustable reactive power, This is the sum of the line inductance from the reference voltage point to the photovoltaic inverter.

15. The control method as described in claim 13, characterized in that, Also includes: When the reactive power at the grid connection point reaches the adjustable reactive power and there is an overvoltage at the grid connection point, the active power at the grid connection point is controlled in ascending order of the active voltage adjustment coefficient at the grid connection point. For the photovoltaic inverter connected at the grid connection point, the active power of the photovoltaic inverter is controlled in ascending order of the active voltage regulation coefficient of the photovoltaic inverter.

16. The control method as described in claim 15, characterized in that, Also includes: When the active voltage regulation coefficients of the photovoltaic inverters are the same, the active power of the photovoltaic inverters is controlled sequentially from the nearest to the farthest from the grid connection point.

17. The control method as described in claim 15, characterized in that, The active voltage regulation coefficient of the photovoltaic inverter is: in, P is the active voltage regulation coefficient of the photovoltaic inverter. ei For adjustable active power of photovoltaic inverters, This is the sum of the line resistances from the reference voltage point to the photovoltaic inverter.

18. The control method as described in claim 1, characterized in that, Also includes: If at least two types of overvoltage exist in the feeder, the transformer area, or the grid connection point, voltage regulation control shall be performed in the order of priority for handling feeder overvoltage, handling transformer area overvoltage, and handling grid connection point overvoltage.

19. The control method as described in claim 1, characterized in that, Also includes: The voltage difference value is obtained by subtracting the collected feeder voltage, transformer area voltage, or grid connection point voltage from the control target voltage; The voltage difference is adjusted by the overall PI active power regulation to obtain the overall active power control target; The individual active power adjustment instructions are obtained based on the overall active power control target.

20. The control method as described in claim 19, characterized in that, The calculation method for the active power regulation command of the individual is as follows: Where ΔP is the total active power control target, P ei For adjustable active power, ΔP i The active power regulation command is given by the individual, and Y is the set of overvoltage feeders.

21. The control method as described in claim 1, characterized in that, Also includes: The voltage difference value is obtained by subtracting the collected feeder voltage, transformer area voltage, or grid connection point voltage from the control target voltage; The voltage difference is processed by the overall PI reactive power regulation to obtain the overall reactive power control target; Individual reactive power adjustment commands are obtained based on the overall reactive power control target.

22. The control method as described in claim 21, characterized in that, The calculation method for the reactive power regulation command of the individual is as follows: Where ΔQ is the total reactive power control target, Q ei For adjustable reactive power, ΔQ i The reactive power regulation command is given by the individual, and Y is the set of overvoltage feeders.

23. An active distribution network overvoltage control system, characterized in that, The control system includes a plurality of photovoltaic inverters, a plurality of grid connection points, a plurality of transformer substations, a plurality of feeders, a plurality of local controllers and a coordination controller. The control system is used to execute the control method as described in any one of claims 1-22, wherein: Any one of the plurality of feeders connects to a plurality of the plurality of transformer substations, any one of the plurality of transformer substations connects to a plurality of the plurality of grid connection points, and any one of the plurality of grid connection points connects to a plurality of the plurality of photovoltaic inverters. The plurality of local controllers are connected one-to-one with the plurality of photovoltaic inverters, and are used to collect photovoltaic inverter information and send active power adjustment commands and reactive power adjustment commands to the corresponding photovoltaic inverters. The photovoltaic inverter information includes grid connection point voltage, output active power, output reactive power, adjustable active power and adjustable reactive power. The coordination controller is connected to the plurality of local controllers, and is used to receive photovoltaic inverter information, connect to the plurality of feeders, obtain a plurality of transformer area voltages and a plurality of feeder voltages, and send the active power regulation command and the reactive power regulation command based on the plurality of transformer area voltages and the plurality of feeder voltages.

24. The control system as described in claim 23, characterized in that, The local controller communicates with the coordinating controller via fiber optic or wireless communication, sending information about the photovoltaic inverter and receiving active power regulation commands and reactive power regulation commands.

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