AVC optimization control method for coordination and cooperation of SVG and inverter of photovoltaic power station

Abstract

The embodiment of the invention discloses a photovoltaic power station SVG and inverter coordinated AVC optimization control method, and the method comprises the steps: carrying out the operation of a station system according to a voltage instruction of a power grid needing to be adjusted by a station, calculating the total reactive power demand of a photovoltaic power station, and calculating the change degree of the total reactive power output to the bus voltage, distributing the calculated reactive power output demand value to each photovoltaic power generation unit and reactive power compensation equipment in the power station according to a formulated reactive power distribution strategy so as to change reactive power output reference values of a photovoltaic inverter and an SVG, so that the bus voltage of the plant station reaches a control target value, and the voltage and reactive power automatic closed-loop control of multiple units of the new energy plant station is realized; and finally, establishing an AVC (Automatic Voltage Control) control overall framework considering the coordination reactive compensation of the SVG and the inverter of the photovoltaic power station. According to the invention, the voltage of the outlet of the station and the voltage of the low-voltage side of the box transformer substation are considered through the AVC regulation in the station, and reactive power distribution is carried out on the SVG and the inverter in the station, so that the voltage requirement is met.

Description

Technical Field

[0001] The present application relates to an AVC optimization control method for coordinated cooperation between SVG and inverter in a photovoltaic power station, belonging to the technical field of voltage regulation in photovoltaic power stations. Background Art

[0002] In recent years, the photovoltaic power generation industry has developed rapidly, the cost of system components has continued to decline, and photovoltaic grid-connected technology has become increasingly mature. The construction of grid-connected photovoltaic power stations has become an effective way to utilize clean energy on a large scale under the background of new power systems. Photovoltaic power stations, especially centralized grid-connected photovoltaic power stations, are generally far away from the power load center, and the power grid system is relatively weak. The photovoltaic power generation system itself will cause grid-connected voltage fluctuations and even exceed the limit due to changes in temperature and light. Therefore, it is necessary for photovoltaic power stations to participate in the voltage regulation control of the power grid system and provide fast reactive power support for the power grid in an emergency. It can effectively improve the voltage limit of photovoltaic grid-connected points and improve the stability and safety of photovoltaic grid-connected points. According to the instructions of the power grid dispatching agency, the photovoltaic power station automatically adjusts the reactive power it emits (or absorbs) to control the voltage of the grid-connected point. Its adjustment speed and control accuracy should meet the requirements of power system voltage regulation, and the photovoltaic power station should make full use of the reactive capacity and regulation capability of the grid-connected inverter; when the reactive capacity of the inverter cannot meet the system voltage regulation needs, a reactive compensation device of appropriate capacity should be installed in the photovoltaic power station.

[0003] The AVC control target of the photovoltaic power station is to meet the system voltage stability needs. The provincial dispatching department sends a dispatching instruction value to the AVC control terminal of the photovoltaic station to maintain the station outlet voltage. The dispatching instruction is issued every 5 minutes. The outlet voltage of the photovoltaic power station is collected 3 minutes after the dispatching instruction value is issued to see whether the station has adjusted to the standard according to the grid requirements. If it does not meet the standard, there will be a response assessment. After receiving the instruction, the AVC on the station side analyzes and calculates the voltage regulation demand, and then uses the reactive power regulation resources in the station to adjust. The AVC regulation in the station takes into account the voltage at the station outlet and the voltage on the low-voltage side of the box transformer, and distributes the reactive power of the SVG and inverter in the station to meet the voltage demand.

[0004] Therefore, how to optimize the power distribution of reactive equipment to reduce the power loss caused by reactive power generation of each device is a technical problem that urgently needs to be solved. Summary of the invention

[0005] To solve the above technical problems, the embodiments of the present application provide an AVC optimization control method for the coordinated cooperation between SVG and inverter in a photovoltaic power station, which optimizes the power distribution of reactive equipment and reduces the power loss caused by reactive power generation of each device.

[0006] Specifically, the present application first calculates the system of the station for the voltage instruction that the power grid wants the station to adjust, calculates the total reactive power demand of the photovoltaic power station and the degree of change of the bus voltage due to the total reactive output considering the parameters of the station equipment, and then distributes the calculated reactive power output demand value to each photovoltaic power generation unit and reactive compensation equipment in the power station according to the formulated reactive power distribution strategy as a control signal to change the reactive power output reference value of the photovoltaic inverter and SVG, so that the bus voltage of the plant station reaches the control target value, and realizes the automatic closed-loop control of the voltage and reactive power of multiple units in the new energy plant station. Finally, based on the above, an overall AVC control framework considering the coordinated reactive compensation of the photovoltaic power station SVG and the inverter is established. The present application designs an AVC optimization control method for the coordinated cooperation of the photovoltaic power station SVG and the inverter, and distributes the reactive power of the SVG and the inverter in the station to meet the voltage demand by adjusting the AVC in the station and considering the voltage at the station outlet and the voltage on the low-voltage side of the box transformer.

[0007] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0008] According to one aspect of an embodiment of the present application, there is provided an AVC optimization control method for coordinated cooperation between SVG and an inverter of a photovoltaic power station, the method comprising:

[0009] Calculate the voltage and reactive power demand at the grid connection point of the PV power station based on the coordination between SVG and inverter;

[0010] Inverter and SVG coordinated reactive power distribution scheme based on AVC control of photovoltaic power station;

[0011] Based on the grid connection point voltage, reactive power demand and reactive power distribution scheme of the photovoltaic power station, an AVC overall control framework considering coordinated reactive power compensation between the photovoltaic power station SVG and the inverter is determined, and AVC optimization control is realized through the AVC overall control framework;

[0012] The calculation is based on the grid connection point voltage and reactive power demand of the photovoltaic power station coordinated by the SVG and the inverter, including:

[0013] Taking the grid system voltage as the reference, the grid connection point voltage of the photovoltaic power station is expressed as:

[0014]

[0015] Where: U PCC is the grid connection point voltage of the photovoltaic power station; U S is the grid system voltage; X and R are the system reactance and resistance; ΔP1 and ΔQ1 are the active loss and reactive loss caused by the station collection line and transformer impedance respectively; P G , Q GThey are respectively the active output and reactive output of the photovoltaic power station inverter; Q C It is the reactive power output of the reactive power compensation device of the photovoltaic power station;

[0016] Considering the impact of active output on the reactive power loss of the box transformer and the main transformer and the impact of active output on the output line voltage, the reactive power demand is:

[0017]

[0018] Where: ΔQ r is the reactive power demand; ΔU PCC is the voltage change at the grid connection point; P is the active output of the photovoltaic power station; ΔP is the active power output change of the photovoltaic power station; S N is the rated capacity of the transformer; U KT % is the short-circuit impedance of the main transformer; U kt % is the short-circuit impedance of the box-type transformer.

[0019] Furthermore, the inverter and SVG coordinated reactive power distribution scheme based on AVC control of photovoltaic power station includes:

[0020] Get the capacity factor λ, participate in adjusting the number of inverters n, and set the maximum reactive power Q for reactive compensation svg , Inverter rated reactive power Q gimax And reactive power target value Q t , when the reactive power regulation of the inverter is not greater than the reactive power compensation, the reactive power distribution scheme is determined as:

[0021] When Q t ≤λQ svg When , voltage regulation is fully allocated to reactive power compensation devices, the inverter does not participate in regulation, the voltage target value is allocated to SVG, and the reactive power allocated by the inverter is zero;

[0022] when When the reactive power is allocated to the inverter first, the reactive power is allocated to the reactive power compensation device secondly;

[0023] when When the reactive power is adjusted to the maximum, the reactive power of each adjustable inverter is adjusted to the maximum, and the remaining voltage is allocated to the reactive power compensation device;

[0024] when When the inverter reactive power is adjusted to the maximum, the target voltage value is sent to the reactive power compensation device and an alarm is sounded.

[0025] Furthermore, the coordinated reactive power distribution scheme between the inverter and SVG based on the AVC control of the photovoltaic power station also includes: when the reactive power adjustment amount of the inverter is greater than the reactive power compensation, waiting for the step cycle to be adjusted multiple times.

[0026] Furthermore, based on the grid connection point voltage, reactive power demand and reactive power distribution scheme of the photovoltaic power station, an AVC overall control framework considering coordinated reactive power compensation between the photovoltaic power station SVG and the inverter is determined, including:

[0027] With the regional AVC system as the master station and the AVC system of the photovoltaic power station as the substation, an overall AVC control framework is established; wherein, the master station takes the qualified voltage of the grid-connected port as the first goal, the power factor of the grid-connected port and the reduction of reactive network loss as the second goal, and takes the minimum number of actions of the photovoltaic power station substation as the constraint condition, and sends real-time voltage instructions and voltage plan curves to the substation; the substation adjusts the output reactive power of the inverter group and SVG according to the voltage instruction, and adjusts the on-load voltage tap position of the main transformer to make the grid-connected point voltage reach the target value.

[0028] Furthermore, the control process of the AVC overall control framework includes:

[0029] Obtain internal information of the photovoltaic power station and upload the target information to the main station;

[0030] According to the deviation between the actual bus voltage value of the photovoltaic grid-connected point and the reference value issued by the dispatching master station, the total reactive power output to be changed in the photovoltaic power station is calculated;

[0031] When SVG participates in reactive power regulation, the reactive power that needs to be changed for each inverter and SVG during regulation is calculated; when SVG does not participate in reactive power regulation, the reactive power that needs to be changed for each inverter during regulation is calculated;

[0032] When the SVG participates in reactive power regulation, the inverter and the SVG complete the regulation according to the received reactive power command; when the SVG does not participate in reactive power regulation, the inverter completes the regulation according to the received reactive power command.

[0033] According to one aspect of the embodiment of the present application, there is provided an AVC optimization control device for coordinated cooperation between SVG and inverter of a photovoltaic power station, comprising:

[0034] A calculation module is configured to calculate the voltage and reactive power demand at the grid connection point of the photovoltaic power station based on the coordination between the SVG and the inverter;

[0035] A distribution module is configured as a coordinated reactive power distribution scheme between an inverter and an SVG based on AVC control of a photovoltaic power station;

[0036] A control module is configured to determine an AVC overall control framework that considers coordinated reactive power compensation between the SVG and the inverter of the photovoltaic power station based on the grid connection point voltage, reactive power demand, and reactive power distribution scheme of the photovoltaic power station, and implement AVC optimization control through the AVC overall control framework;

[0037] The computing module is further configured to:

[0038] Taking the grid system voltage as the reference, the grid connection point voltage of the photovoltaic power station is expressed as:

[0039]

[0040] Where: U PCC is the grid connection point voltage of the photovoltaic power station; U S is the grid system voltage; X and R are the system reactance and resistance; ΔP1 and ΔQ1 are the active loss and reactive loss caused by the station collection line and transformer impedance respectively; P G , Q G They are respectively the active output and reactive output of the photovoltaic power station inverter; Q C It is the reactive power output of the reactive power compensation device of the photovoltaic power station;

[0041] Considering the impact of active output on the reactive power loss of the box transformer and the main transformer and the impact of active output on the output line voltage, the reactive power demand is:

[0042]

[0043] Where: ΔQ r is the reactive power demand; ΔU PCC is the voltage change at the grid connection point; P is the active output of the photovoltaic power station; ΔP is the active power output change of the photovoltaic power station; S N is the rated capacity of the transformer; U KT % is the short-circuit impedance of the main transformer; U kt % is the short-circuit impedance of the box-type transformer.

[0044] According to one aspect of an embodiment of the present application, an electronic device is provided, including: a controller; a memory for storing one or more programs, and when the one or more programs are executed by the controller, the controller implements the above-mentioned AVC optimization control method for coordinated cooperation between the SVG and the inverter of the photovoltaic power station.

[0045] According to one aspect of an embodiment of the present application, a computer-readable storage medium is also provided, on which computer-readable instructions are stored. When the computer-readable instructions are executed by a processor of a computer, the computer executes the above-mentioned AVC optimization control method for coordinated cooperation between the SVG and the inverter of the photovoltaic power station.

[0046] According to one aspect of the embodiments of the present application, a computer program product or a computer program is also provided, the computer program product or the computer program including computer instructions, the computer instructions being stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the above-mentioned AVC optimization control method for the coordinated cooperation between the SVG and the inverter of the photovoltaic power station.

[0047] The technical solution provided in the embodiments of the present application has at least the following advantages:

[0048] For the voltage regulation of photovoltaic power stations, this application designs the AVC grid-connected point voltage and reactive demand calculation strategy and the inverter and SVG reactive coordination control strategy by analyzing the impact of active power changes, reactive output, and reactive loss on voltage regulation in the photovoltaic power station. Through the coordinated control of SVG and photovoltaic inverters, the PCC voltage can be quickly and effectively maintained to avoid or reduce the active power loss caused by unreasonable reactive flow. Combined with the characteristics of photovoltaic power stations, the needs of power grids and power generation companies are fully considered, and the target power is adaptively dispatched and allocated to allocate the reactive output of inverters and SVGs with the optimal combination strategy, so as to achieve batch regulation and fine-tuning and improve the refined operation of regulation.

[0049] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0051] Figure 1 It is a structural diagram of an AVC optimized control photovoltaic power station grid-connected system in which a photovoltaic power station SVG and an inverter cooperate with each other according to an exemplary embodiment of the present application;

[0052] Figure 2 It is an overall flow chart of an AVC optimization control method for coordinated cooperation between SVG and inverter in a photovoltaic power station shown in an exemplary embodiment of the present application;

[0053] Figure 3 is a structural diagram of an AVC overall control framework shown in an exemplary embodiment of the present application;

[0054] Figure 4This is a control flow of the AVC overall control framework shown in an exemplary embodiment of the present application. Figure 1 ;

[0055] Figure 5 This is a control flow of the AVC overall control framework shown in an exemplary embodiment of the present application. Figure 2 ;

[0056] Figure 6 It is a structural diagram of an AVC optimization control device for coordinated cooperation between SVG and inverter in a photovoltaic power station shown in an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0057] Here, exemplary embodiments will be described in detail, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are only examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

[0058] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0059] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0060] The term "multiple" as used in this application refers to two or more than two. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

[0061] See also Figure 1 , Figure 1An exemplary embodiment of the present application shows a structural diagram of a photovoltaic power station grid-connected system in which a photovoltaic power station SVG and an inverter cooperate with each other in an AVC optimization control. The photovoltaic power station grid-connected system in which a photovoltaic power station SVG and an inverter cooperate with each other in an AVC optimization control includes a photovoltaic power station inverter G1, a dynamic reactive power compensation device G2, and a power grid. The photovoltaic power station inverter G1 and the dynamic reactive power compensation device G2 are connected in parallel and then connected to the power grid through the photovoltaic power station transmission line; the impedance Z of the photovoltaic power station transmission line is S =R+jX; X, R are system reactance and resistance; U PCC is the grid-connected point voltage of the photovoltaic power station, U S is the grid system voltage; U G It is the low-voltage side voltage of the transformer at the photovoltaic power station outlet.

[0062] One aspect of the present application provides an AVC optimization control method for the coordinated cooperation between SVG and inverter in a photovoltaic power station. The method can be applied to Figure 1 The PV power station SVG and inverter coordinate with each other in the AVC optimization control PV power station grid-connected system. It should be noted that Figure 1 The photovoltaic power station grid-connected system shown is only an example of a grid-connected system to which the method proposed in the embodiment of the present application can be applied, and does not mean that the present application must be applied to the system. Figure 1 This is just an example of a grid-connected system and does not constitute a limitation to this application. Figure 2 , Figure 2 This is an overall flow chart of an AVC optimization control method for coordinated cooperation between SVG and inverter in a photovoltaic power station shown in an exemplary embodiment of the present application. The method includes steps S100 to S300, which are described in detail as follows.

[0063] S100: Calculate the voltage and reactive power demand at the grid connection point of the PV power station based on the coordination between SVG and inverter.

[0064] In this embodiment, the reactive source of the photovoltaic power station mainly includes photovoltaic inverters, static VAR generators (SVG) configured in the station, etc. The SVG needs to be configured according to the actual situation of the photovoltaic power station project, such as the distribution of the collection lines in the station, the length of the transmission lines, the installation form and capacity of the project, the access situation of the photovoltaic grid-connected point to the power grid, etc. It is determined after the reactive voltage study, and it outputs the reactive current that meets the requirements by changing the phase angle and amplitude of the AC voltage of the bridge circuit to achieve reactive compensation. The photovoltaic inverter only needs to improve the control strategy to achieve reactive power output without adding additional equipment, which can greatly reduce the investment cost of the photovoltaic power station. The automatic voltage control (AVC) system substation configured in the photovoltaic power station receives the instructions of the dispatching master station, issues reactive distribution control instructions to the reactive power sources (inverters, SVG, etc.) in the station, and adjusts the voltage at the grid connection point. Combined with Figure 1 The photovoltaic power station grid-connected system shown. With the grid system voltage U S As a benchmark, the grid-connected voltage U PCC It can be approximately expressed as:

[0065]

[0066] Where: U S is the grid system voltage; X, R are the system reactance and resistance; ΔP1 and ΔQ1 are the active loss and reactive loss caused by the station collection line and transformer impedance respectively; P G , Q G They are respectively the active output and reactive output of the photovoltaic power station inverter; Q C is the reactive power output of the reactive power compensation device of the photovoltaic power station; U G It is the low-voltage side voltage of the transformer at the photovoltaic power station outlet.

[0067] Photovoltaic power station active output P G Changes will cause the grid-connected voltage U PCC This can be solved by adjusting the reactive power output Q of the inverter in the station. G , reactive power compensation device reactive power output Q C , so as to achieve the purpose of regulating the voltage at the grid connection point of the photovoltaic power station.

[0068] In the voltage tracking control mode, the reactive power demand is calculated by formula (2) to realize the conversion from voltage command to reactive power command. Among them, the reactive power regulation is a function of the voltage regulation command and the current active power output. When the active power output does not change much near a certain power point, the reactive power and voltage are proportional. However, when the power changes too much, the reactive power and voltage are no longer proportional. Considering the impact of active power output on the reactive power loss of the box transformer and the main transformer and the impact of active power output on the output line voltage, the reactive power demand ΔQ r for:

[0069]

[0070] Where: ΔU PCC is the voltage change at the grid connection point; P is the active output of the photovoltaic power station; ΔP is the active power output change of the photovoltaic power station; S N is the rated capacity of the transformer; U KT % is the short-circuit impedance of the main transformer; U kt % is the short-circuit impedance of the box-type transformer.

[0071] S200: A coordinated reactive power distribution scheme between inverter and SVG based on AVC control of photovoltaic power station.

[0072] In an exemplary embodiment, the voltage data of the grid connection point is first obtained, and the real-time voltage value is U PCC , the voltage difference is ΔU PCC , determine whether the voltage difference is within the control range, if so, wait for the next cycle to control, calculate the total reactive power demand of the photovoltaic power station according to formula (2), under the preset protection constraints, such as communication interruption protection conditions, state quantity blocking protection conditions and analog quantity over-limit protection conditions, if each inverter and reactive power compensation device meets the conditions, it will participate in reactive power voltage control; if it does not meet the constraints, it will not participate in reactive power voltage control. According to the target reactive power value, the inverter and reactive power compensation device are regulated, and the specific method is as follows:

[0073] Assume λ is the capacity factor; n is the number of inverters involved in regulation; Q svg Set the maximum reactive power for reactive power compensation; Q gimax is the rated reactive power of the inverter; Q t is the reactive power target value. The reactive power adjustment of the inverter cannot be greater than the reactive power compensation. If it is greater, it needs to wait for the step cycle to adjust multiple times. The designed reactive power distribution scheme is as follows:

[0074] 1) Q t ≤λQ svg , when the reactive power target value is not greater than the reactive power compensation device capacity factor λQ svg When the voltage is fully controlled, the reactive power compensation device is allocated, and the inverter does not participate in the control. The voltage target value is allocated to the SVG, and the reactive power allocated to the inverter is zero.

[0075] 2) When the reactive power target value is greater than the reactive power compensation device coefficient capacity λQ svg And not greater than the coefficient capacity λQ of the reactive power compensation device svg When the reactive power is added to the rated reactive capacity of the inverter, the reactive power is allocated to the inverter first, and then to the reactive power compensation device.

[0076] 3) When the reactive power target value is greater than the reactive power compensation device coefficient capacity λQ svg The sum of the rated reactive capacity of the inverter and not greater than the capacity of the reactive compensation device λQ svg When the reactive power is equal to the sum of the rated reactive power capacity of the inverter, this regulation is jointly undertaken by the reactive power compensation device and the inverter, and is allocated to the inverter reactive power first, that is, the reactive power of each adjustable inverter is adjusted to the maximum, and the remaining voltage is allocated to the reactive power compensation device.

[0077] 4) When the reactive power target value is greater than the sum of the reactive power compensation device capacity and the rated reactive power capacity of the inverter, the reactive power of the inverter is adjusted to the maximum, the target voltage value is sent to the reactive power compensation device and an alarm is sounded.

[0078] In an exemplary embodiment, when adjusting the reactive power of the inverter, it is necessary to satisfy that the reactive power adjusted each time is not greater than the reactive compensation, so the reactive power of the inverter is adjusted in the following manner: ① The reactive power allocated to the inverter is not greater than the reactive compensation, and it is adjusted in one time; ② The reactive power allocated to the inverter is greater than the reactive compensation, and it is adjusted in multiple times, first adjusting according to the step size and waiting for the compensation cycle before continuing to adjust.

[0079] S300: Based on the voltage at the grid connection point of the photovoltaic power station, the reactive power demand and the reactive power distribution plan, determine the AVC overall control framework that considers the coordinated reactive power compensation between the photovoltaic power station SVG and the inverter, and implement AVC optimization control through the AVC overall control framework.

[0080] In an exemplary embodiment, see Figure 3 , Figure 3 300 is a structural diagram of an AVC overall control framework shown in an exemplary embodiment of the present application. The AVC overall control framework includes a master station 301 and a substation 302, wherein the master station 301 and the substation 302 are signal-connected. In step S300, the AVC overall control framework considering the coordinated reactive power compensation of the photovoltaic power station SVG and the inverter is determined specifically through the following steps:

[0081] The regional AVC system is used as the master station 301, and the AVC system of the photovoltaic power station is used as the substation 302. The master station 301 also has the control function of the substation 302. The overall control mode adopts a three-level coordinated control mode of reactive voltage master station side, plant station side and equipment side. The master station 301 takes the qualified voltage of the grid-connected port as the main goal (the first goal), the power factor of the grid-connected port and the reduction of reactive network loss as the secondary goals (the second goal), and the minimum number of actions of the photovoltaic power station substation as the constraint condition, and sends real-time voltage instructions and voltage plan curves to the substation 302. The substation 302 adjusts the output reactive power of the inverter group and SVG and other reactive power sources according to the voltage instruction, and adjusts the on-load voltage tap position of the main transformer to make the voltage at the grid-connected point reach the target value.

[0082] In an exemplary embodiment, see Figure 4 , Figure 4 This is a control flow of the AVC overall control framework shown in an exemplary embodiment of the present application. Figure 1 The control process of the AVC overall control framework includes steps S401-404.

[0083] S401: Data collection: Obtain the internal information of the photovoltaic power station and send the target information to the main station.

[0084] In this embodiment, the target information is information required to implement AVC optimization control, such as information required to calculate the voltage and reactive power demand at the grid connection point of the photovoltaic power station and information required to generate a reactive power distribution plan.

[0085] S402: Calculation of reactive power demand: Calculate the total reactive power output that needs to be changed in the PV power station based on the deviation between the actual bus voltage value at the PV grid-connected point and the reference value issued by the dispatching master station.

[0086] S403: Reactive power distribution: When the SVG participates in reactive power regulation, the reactive power amount that needs to be changed for each inverter and the SVG during regulation is calculated; when the SVG does not participate in reactive power regulation, the reactive power amount that needs to be changed for each inverter during regulation is calculated.

[0087] S404: Reactive power command execution: When the SVG participates in reactive power regulation, the inverter and the SVG complete the regulation according to the received reactive power command; when the SVG does not participate in reactive power regulation, the inverter completes the regulation according to the received reactive power command.

[0088] In an exemplary embodiment, see Figure 5 , Figure 5 This is a control flow of the AVC overall control framework shown in an exemplary embodiment of the present application. Figure 2 The control process of the AVC overall control framework includes steps S501 to S507.

[0089] S501: Acquire real-time data of the device.

[0090] S502: Calculate the real-time target voltage value.

[0091] S503: Determine whether the plant function is put into closed loop.

[0092] S504: Judgment | actual value - target value | > dead zone value.

[0093] S505: Whether the safety constraint condition is met.

[0094] S506: Control mode is determined.

[0095] S507: Generate a regulation control strategy based on the principle of giving priority to satisfying regulation targets and then considering economic control.

[0096] In this embodiment, steps S501 to S507 can be executed by the main station, wherein the acquisition of the real-time data of the equipment in step S501 can be obtained by collecting the corresponding data through the substation and uploading it to the main station. After obtaining the real-time data of the equipment, step S502 can calculate the reactive power demand as the real-time target value of the voltage based on formula (1) and formula (2). The purpose of steps S503 to S505 is to determine whether the grid-connected system is operating normally. The control mode determined in step S506 is one of the three-level coordinated control modes of reactive voltage master station side, plant station side and equipment side, which is used to determine the control side. The specific adjustment control strategy in step S507 can be based on Figure 2 The reactive power distribution scheme generated by step S300 is shown. According to the adjustment control strategy, the corresponding control instructions can be generated. After the control instructions are sent to the substation, the substation includes a photovoltaic power station monitoring system and a reactive power compensation control system, and the corresponding control instructions are executed according to different control objects. If it is necessary to adjust the inverter device or the SVC device, the photovoltaic power station monitoring system or the reactive power compensation control system executes the control instructions. If it is necessary to adjust the inverter device and the SVC device at the same time, the photovoltaic power station monitoring system and the reactive power compensation control system respectively execute the control instructions at the same time. For example, the control instructions can be divided into a first instruction and a second instruction for adjusting the inverter device and the SVC device. The first instruction is sent to the photovoltaic power station monitoring system, and the second instruction is sent to the reactive power compensation control system.

[0097] See also Figure 6 , Figure 6 It is a structural diagram of an AVC optimization control device for coordinating between SVG and inverter of a photovoltaic power station shown in an exemplary embodiment of the present application. Another aspect of the embodiment of the present invention further provides an AVC optimization control device for coordinating between SVG and inverter of a photovoltaic power station, the device comprising:

[0098] The calculation module 601 is configured to calculate the grid connection point voltage and reactive power demand of the photovoltaic power station based on the coordination between the SVG and the inverter;

[0099] The allocation module 602 is configured to coordinate reactive power allocation scheme between inverter and SVG based on AVC control of photovoltaic power station;

[0100] The control module 603 is configured to determine an AVC overall control framework that considers coordinated reactive power compensation between the SVG and the inverter of the photovoltaic power station based on the grid connection point voltage, reactive power demand, and reactive power distribution scheme of the photovoltaic power station, and implement AVC optimization control through the AVC overall control framework;

[0101] The calculation module 601 is further configured to:

[0102] Taking the grid system voltage as the reference, the grid connection point voltage of the photovoltaic power station is expressed as:

[0103]

[0104] Where: U PCC is the grid connection point voltage of the photovoltaic power station; U S is the grid system voltage; X and R are the system reactance and resistance; ΔP1 and ΔQ1 are the active loss and reactive loss caused by the station collection line and transformer impedance respectively; P G , Q G They are respectively the active output and reactive output of the photovoltaic power station inverter; Q C It is the reactive power output of the reactive power compensation device of the photovoltaic power station;

[0105] Considering the impact of active output on the reactive power loss of the box transformer and the main transformer and the impact of active output on the output line voltage, the reactive power demand is:

[0106]

[0107] Where: ΔQ r is the reactive power demand; ΔU PCC is the voltage change at the grid connection point; P is the active output of the photovoltaic power station; ΔP is the active power output change of the photovoltaic power station; S N is the rated capacity of the transformer; U KT % is the short-circuit impedance of the main transformer; U kt % is the short-circuit impedance of the box-type transformer.

[0108] In some embodiments, the allocation module is further configured to:

[0109] Get the capacity factor λ, participate in adjusting the number of inverters n, and set the maximum reactive power Q for reactive compensation svg , Inverter rated reactive power Q gimax And reactive power target value Q t , when the reactive power regulation of the inverter is not greater than the reactive power compensation, the reactive power distribution scheme is determined as:

[0110] When Q t ≤λQ svg When , voltage regulation is fully allocated to reactive power compensation devices, the inverter does not participate in regulation, the voltage target value is allocated to SVG, and the reactive power allocated by the inverter is zero;

[0111] when When the reactive power is allocated to the inverter first, the reactive power is allocated to the reactive power compensation device secondly;

[0112] when When the reactive power is adjusted to the maximum, the reactive power of each adjustable inverter is adjusted to the maximum, and the remaining voltage is allocated to the reactive power compensation device;

[0113] when When the inverter reactive power is adjusted to the maximum, the target voltage value is sent to the reactive power compensation device and an alarm is sounded.

[0114] In some embodiments, the control module is further configured to:

[0115] With the regional AVC system as the master station and the AVC system of the photovoltaic power station as the substation, an overall AVC control framework is established; wherein, the master station takes the qualified voltage of the grid-connected port as the first goal, the power factor of the grid-connected port and the reduction of reactive network loss as the second goal, and takes the minimum number of actions of the photovoltaic power station substation as the constraint condition, and sends real-time voltage instructions and voltage plan curves to the substation; the substation adjusts the output reactive power of the inverter group and SVG according to the voltage instruction, and adjusts the on-load voltage tap position of the main transformer to make the grid-connected point voltage reach the target value.

[0116] In some embodiments, the control process of the AVC overall control framework includes:

[0117] Obtain internal information of the photovoltaic power station and upload the target information to the main station;

[0118] According to the deviation between the actual bus voltage value of the photovoltaic grid-connected point and the reference value issued by the dispatching master station, the total reactive power output to be changed in the photovoltaic power station is calculated;

[0119] When SVG participates in reactive power regulation, the reactive power that needs to be changed for each inverter and SVG during regulation is calculated; when SVG does not participate in reactive power regulation, the reactive power that needs to be changed for each inverter during regulation is calculated;

[0120] When the SVG participates in reactive power regulation, the inverter and the SVG complete the regulation according to the received reactive power command; when the SVG does not participate in reactive power regulation, the inverter completes the regulation according to the received reactive power command.

[0121] It should be noted that the AVC optimization control device for coordinated cooperation between the photovoltaic power station SVG and the inverter provided in the above embodiment and the AVC optimization control method for coordinated cooperation between the photovoltaic power station SVG and the inverter provided in the above embodiment belong to the same concept, and the specific manner of executing the step operation has been described in detail in the method embodiment and will not be repeated here.

[0122] Another aspect of the present application provides an electronic device, including: a controller; a memory for storing one or more programs, which, when executed by the controller, executes the AVC optimization control method for coordinated cooperation between the SVG and the inverter of the photovoltaic power station in the above-mentioned embodiments.

[0123] In particular, according to an embodiment of the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a computer program for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication part, and / or installed from a removable medium. When the computer program is executed by a central processing unit (CPU) 701, various functions defined in the system of the present application are executed.

[0124] It should be noted that the computer-readable medium shown in the embodiment of the present application can be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium can be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media can include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a flash memory, an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable storage medium can be any tangible medium containing or storing a program, which can be used by an instruction execution system, device or device or used in combination with it. In the present application, a computer-readable signal medium can include a data signal propagated in a baseband or as a part of a carrier wave, wherein a computer-readable computer program is carried. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, which may send, propagate, or transmit programs for use by or in conjunction with an instruction execution system, apparatus, or device. The computer program contained on the computer-readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

[0125] The flowchart and block diagram in the accompanying drawings illustrate the possible architecture, functions and operations of the system, method and computer program product according to various embodiments of the present application. Wherein, each box in the flowchart or block diagram can represent a module, a program segment, or a part of the code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order than the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0126] The modules / units involved in the embodiments described in this application may be implemented by software or hardware, and the described units may also be set in a processor. The names of these modules / units do not, in some cases, constitute limitations on the modules / units themselves.

[0127] Another aspect of the present application further provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the AVC optimization control method for the coordinated cooperation between the SVG and the inverter of the photovoltaic power station as described above is implemented. The computer-readable storage medium may be included in the electronic device described in the above embodiment, or may exist independently without being assembled into the electronic device.

[0128] Another aspect of the present application also provides a computer program product or a computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the AVC optimization control method for the coordinated cooperation between the SVG and the inverter of the photovoltaic power station provided in the above-mentioned embodiments.

[0129] According to one aspect of an embodiment of the present application, a computer system is also provided, including a central processing unit (CPU), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) or a program loaded from a storage portion into a random access memory (RAM), such as executing the method in the above embodiment. In RAM, various programs and data required for system operation are also stored. CPU, ROM and RAM are connected to each other via a bus. An input / output (I / O) interface is also connected to the bus.

[0130] The following components are connected to the I / O interface: an input part including a keyboard, a mouse, etc.; an output part including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker; a storage part including a hard disk, etc.; and a communication part including a network interface card such as a LAN (Local Area Network) card, a modem, etc. The communication part performs communication processing via a network such as the Internet. A drive is also connected to the I / O interface as needed. Removable media, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., are installed on the drive as needed so that the computer program read therefrom is installed into the storage part as needed.

[0131] The above content is only a preferred exemplary embodiment of the present application and is not intended to limit the implementation scheme of the present application. A person skilled in the art can easily make corresponding changes or modifications based on the main concept and spirit of the present application. Therefore, the scope of protection of the present application shall be based on the scope of protection required by the claims.

Claims

1. A method for optimizing the AVC control of the coordinated cooperation between SVG and inverter in a photovoltaic power station, characterized in that: The method comprises: Calculate the voltage and reactive power demand at the grid connection point of the PV power station based on the coordination between SVG and inverter; Inverter and SVG coordinated reactive power distribution scheme based on AVC control of photovoltaic power station; Based on the grid connection point voltage, reactive power demand and reactive power distribution scheme of the photovoltaic power station, an AVC overall control framework considering coordinated reactive power compensation between the photovoltaic power station SVG and the inverter is determined, and AVC optimization control is realized through the AVC overall control framework; The calculation is based on the grid connection point voltage and reactive power demand of the photovoltaic power station coordinated by the SVG and the inverter, including: Taking the grid system voltage as the reference, the grid connection point voltage of the photovoltaic power station is expressed as: Where: U PCC is the grid connection point voltage of the photovoltaic power station; U S is the grid system voltage; X and R are the system reactance and resistance; ΔP1 and ΔQ1 are the active loss and reactive loss caused by the station collection line and transformer impedance respectively; P G , Q G They are respectively the active output and reactive output of the photovoltaic power station inverter; Q C It is the reactive power output of the reactive power compensation device of the photovoltaic power station; Considering the impact of active output on the reactive power loss of the box transformer and the main transformer and the impact of active output on the output line voltage, the reactive power demand is: Where: ΔQ r is the reactive power demand; ΔU PCC is the voltage change at the grid connection point; P is the active output of the photovoltaic power station; ΔP is the active power output change of the photovoltaic power station; S N is the rated capacity of the transformer; U KT % is the short-circuit impedance of the main transformer; U kt % is the short-circuit impedance of the box-type transformer.

2. The AVC optimization control method for coordinated cooperation between SVG and inverter in a photovoltaic power station according to claim 1 is characterized in that: The inverter and SVG coordinated reactive power distribution scheme based on AVC control of photovoltaic power plants includes: Get the capacity factor λ, participate in adjusting the number of inverters n, and set the maximum reactive power Q for reactive compensation svg , Inverter rated reactive power Q gimax And reactive power target value Q t , when the reactive power regulation of the inverter is not greater than the reactive power compensation, the reactive power distribution scheme is determined as: When Q t ≤λQ svg When , voltage regulation is fully allocated to reactive power compensation devices, the inverter does not participate in regulation, the voltage target value is allocated to SVG, and the reactive power allocated by the inverter is zero; when When the reactive power is allocated to the inverter first, the reactive power is allocated to the reactive power compensation device secondly; when When the reactive power is adjusted to the maximum, the reactive power of each adjustable inverter is adjusted to the maximum, and the remaining voltage is allocated to the reactive power compensation device; when When the inverter reactive power is adjusted to the maximum, the target voltage value is sent to the reactive power compensation device and an alarm is sounded.

3. The AVC optimization control method for coordinated cooperation between SVG and inverter in a photovoltaic power station according to claim 2 is characterized in that: The inverter and SVG coordinated reactive power distribution scheme based on AVC control of photovoltaic power station also includes: when the reactive power adjustment amount of the inverter is greater than the reactive power compensation, the step cycle is waited for to be adjusted multiple times.

4. The AVC optimization control method for coordinated cooperation between SVG and inverter in a photovoltaic power station according to claim 1, characterized in that: Based on the grid connection point voltage, reactive power demand and reactive power distribution scheme of the photovoltaic power station, an AVC overall control framework considering coordinated reactive power compensation between the photovoltaic power station SVG and the inverter is determined, including: With the regional AVC system as the master station and the AVC system of the photovoltaic power station as the substation, an overall AVC control framework is established; wherein, the master station takes the qualified voltage of the grid-connected port as the first goal, the power factor of the grid-connected port and the reduction of reactive network loss as the second goal, and takes the minimum number of actions of the photovoltaic power station substation as the constraint condition, and sends real-time voltage instructions and voltage plan curves to the substation; the substation adjusts the output reactive power of the inverter group and SVG according to the voltage instruction, and adjusts the on-load voltage tap position of the main transformer to make the grid-connected point voltage reach the target value.

5. The AVC optimization control method for coordinated cooperation between SVG and inverter in a photovoltaic power station according to claim 4 is characterized in that: The control process of the AVC overall control framework includes: Obtain internal information of the photovoltaic power station and upload the target information to the main station; According to the deviation between the actual bus voltage value of the photovoltaic grid-connected point and the reference value issued by the dispatching master station, the total reactive power output to be changed in the photovoltaic power station is calculated; When SVG participates in reactive power regulation, the reactive power that needs to be changed for each inverter and SVG during regulation is calculated; when SVG does not participate in reactive power regulation, the reactive power that needs to be changed for each inverter during regulation is calculated; When the SVG participates in reactive power regulation, the inverter and the SVG complete the regulation according to the received reactive power command; when the SVG does not participate in reactive power regulation, the inverter completes the regulation according to the received reactive power command.

6. An AVC optimization control device for coordinated cooperation between SVG and inverter in a photovoltaic power station, characterized in that: The device comprises: A calculation module is configured to calculate the voltage and reactive power demand at the grid connection point of the photovoltaic power station based on the coordination between the SVG and the inverter; A distribution module is configured as a coordinated reactive power distribution scheme between an inverter and an SVG based on AVC control of a photovoltaic power station; A control module is configured to determine an AVC overall control framework that considers coordinated reactive power compensation between the SVG and the inverter of the photovoltaic power station based on the grid connection point voltage, reactive power demand, and reactive power distribution scheme of the photovoltaic power station, and implement AVC optimization control through the AVC overall control framework; The computing module is further configured to: Taking the grid system voltage as the reference, the grid connection point voltage of the photovoltaic power station is expressed as: Where: U PCC is the grid connection point voltage of the photovoltaic power station; U S is the grid system voltage; X and R are the system reactance and resistance; ΔP1 and ΔQ1 are the active loss and reactive loss caused by the station collection line and transformer impedance respectively; P G , Q G They are respectively the active output and reactive output of the photovoltaic power station inverter; Q C It is the reactive power output of the reactive power compensation device of the photovoltaic power station; Considering the impact of active output on the reactive power loss of the box transformer and the main transformer and the impact of active output on the output line voltage, the reactive power demand is: Where: ΔQ r is the reactive power demand; ΔU PCC is the voltage change at the grid connection point; P is the active output of the photovoltaic power station; ΔP is the active power output change of the photovoltaic power station; S N is the rated capacity of the transformer; U KT % is the short-circuit impedance of the main transformer; U kt % is the short-circuit impedance of the box-type transformer.

7. The AVC optimization control device for coordinated cooperation between SVG and inverter in a photovoltaic power station according to claim 6, characterized in that: The allocation module is further configured to: Get the capacity factor λ, participate in adjusting the number of inverters n, and set the maximum reactive power Q for reactive compensation svg , Inverter rated reactive power Q gimax And reactive power target value Q t , when the reactive power regulation of the inverter is not greater than the reactive power compensation, the reactive power distribution scheme is determined as: When Q t ≤λQ svg When , voltage regulation is fully allocated to reactive power compensation devices, the inverter does not participate in regulation, the voltage target value is allocated to SVG, and the reactive power allocated by the inverter is zero; when When the reactive power is allocated to the inverter first, the reactive power is allocated to the reactive power compensation device secondly; when When the reactive power is adjusted to the maximum, the reactive power of each adjustable inverter is adjusted to the maximum, and the remaining voltage is allocated to the reactive power compensation device; when When the inverter reactive power is adjusted to the maximum, the target voltage value is sent to the reactive power compensation device and an alarm is sounded.

8. The AVC optimization control device for coordinated cooperation between SVG and inverter in a photovoltaic power station according to claim 6, characterized in that: The control module is further configured to: With the regional AVC system as the master station and the AVC system of the photovoltaic power station as the substation, an overall AVC control framework is established; wherein, the master station takes the qualified voltage of the grid-connected port as the first goal, the power factor of the grid-connected port and the reduction of reactive network loss as the second goal, and takes the minimum number of actions of the photovoltaic power station substation as the constraint condition, and sends real-time voltage instructions and voltage plan curves to the substation; the substation adjusts the output reactive power of the inverter group and SVG according to the voltage instruction, and adjusts the on-load voltage tap position of the main transformer to make the grid-connected point voltage reach the target value.

9. An electronic device, characterized in that: include: Controller; A memory for storing one or more programs. When the one or more programs are executed by the controller, the controller implements the AVC optimization control method for coordinated cooperation between the SVG and the inverter of the photovoltaic power station according to any one of claims 1 to 5.

10. A computer-readable storage medium, characterized in that: Computer-readable instructions are stored thereon, and when the computer-readable instructions are executed by a processor of a computer, the computer is enabled to execute the AVC optimization control method for coordinated cooperation between the SVG and the inverter of a photovoltaic power station according to any one of claims 1 to 5.

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