Box transformer low-voltage side distributed reactive power compensation system and method based on wind speed detection

Abstract

The application provides a box transformer low-voltage side distributed reactive power compensation system and method based on wind speed detection. A distributed capacitor compensation device is installed on the low-voltage side bus of each box transformer, and an intelligent monitoring control unit is arranged to obtain wind speed information and voltage information in real time, and generate an operation instruction according to the wind speed information and the voltage information, so as to control the input or removal of the distributed capacitor compensation device. The above technical scheme uses the wind speed information as a feedforward criterion to realize advanced response, overcomes the lag defect of the traditional voltage deviation feedback control, and at the same time, uses the voltage information for closed-loop verification to ensure the compensation accuracy. By moving the compensation point to the low-voltage side of the box transformer, the reactive power is compensated on site at each fan terminal, the line loss caused by long-distance transmission is avoided, and the investment cost of the centralized SVG equipment is reduced, so that the voltage drop under the low-wind-speed working condition is effectively inhibited, and the safety and economy of the wind farm operation are improved.

Description

Technical Field

[0001] This invention relates to the field of reactive power compensation technology for wind farms, specifically to a distributed reactive power compensation system and method for the low-voltage side of a transformer substation based on wind speed detection. Background Technology

[0002] As wind power accounts for an increasing proportion of the power system, the problem of reactive power and voltage control in wind farms is becoming increasingly prominent. Especially under low wind speed conditions, wind turbines absorb a large amount of inductive reactive power due to excitation requirements, resulting in a significant voltage drop at the grid connection point and the end of the collection line. In severe cases, this may trigger the wind turbine's low voltage protection to disconnect from the grid, affecting the power generation efficiency of the wind farm and the safe and stable operation of the power grid.

[0003] Currently, reactive power control in wind farms mainly adopts a centralized compensation method based on voltage deviation feedback. This involves installing a Dynamic Var Compensator (SVG) at the substation, injecting capacitive reactive power into the system with the grid connection voltage as the control target. This method has the following drawbacks: First, control relies on deviation information after voltage dips, making it a deviation-driven feedback regulation with a slow response speed, making it difficult to adapt to rapid fluctuations in wind turbine reactive power at low wind speeds. Second, centralized compensation cannot accurately match the different reactive power demands of each wind turbine, resulting in low compensation accuracy and an inability to achieve local reactive power balance. Third, SVG equipment needs to be installed on the high-voltage side and requires additional land acquisition, leading to high investment costs. Fourth, capacitive reactive power needs to be transmitted long distances from the substation to each wind turbine terminal, resulting in significant active power losses due to reactive current in the line resistance, leading to high system losses. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the aforementioned technologies by proposing a distributed reactive power compensation system and method for the low-voltage side of a transformer substation based on wind speed detection. This aims to solve the problem of how to move the compensation point forward to each wind turbine terminal, achieve local reactive power compensation on the low-voltage side of the transformer substation, and construct a control mechanism that can balance rapid response and accurate compensation.

[0005] This invention provides a distributed reactive power compensation system for the low-voltage side of a box-type transformer based on wind speed detection, comprising several box-type transformers. The high-voltage side of each box-type transformer is connected to the wind farm collection line, and the low-voltage side is electrically connected to the corresponding wind turbine generator set, for boosting the output voltage of the corresponding wind turbine generator set. Distributed capacitor compensation devices are installed on the low-voltage side busbar of each box-type transformer and are electrically connected to the low-voltage side busbar of the box-type transformer. They are used to provide capacitive reactive power to the low-voltage side of the box-type transformer as needed. The intelligent monitoring and control unit is electrically connected to each distributed capacitor compensation device. It is used to acquire wind speed information at the location of each wind turbine generator and voltage / current information of the low-voltage side bus of the box transformer. Based on the wind speed information and voltage / current information, it generates control commands to control whether the distributed capacitor compensation device performs capacitive reactive power compensation on the low-voltage side of the corresponding box transformer.

[0006] Preferably, the intelligent monitoring and control unit includes a wind speed sensor, a voltage detection module, and a controller. The wind speed sensor and the voltage / current detection module are respectively connected to the controller, and the sampling terminal of the voltage / current detection module is connected to the low-voltage side bus of the box-type transformer.

[0007] Based on the received wind speed information and the voltage / current information on the low-voltage side of the box-type transformer, the controller generates a first control command, including: When the wind speed is lower than the first wind speed threshold and the voltage / current is higher than the first voltage / current threshold, or when the wind speed is lower than the second wind speed threshold and the voltage / current is higher than the first voltage / current threshold, an instruction is generated for the distributed capacitor compensation device to maintain the current state. When the wind speed is lower than the first wind speed threshold and the voltage / current is lower than the first voltage / current threshold, or when the wind speed is lower than the second wind speed threshold and the voltage / current is lower than the first voltage / current threshold, an instruction is generated for the distributed capacitor compensation device to perform capacitive reactive power compensation on the low-voltage side of the corresponding box transformer. When the wind speed is higher than the second wind speed threshold, or the voltage / current is higher than the second voltage / current threshold, an instruction is generated to disconnect the distributed capacitor compensation device from the low-voltage side of the corresponding box transformer to perform capacitive reactive power compensation. The second wind speed threshold is greater than the first wind speed threshold, and the second voltage / current threshold is greater than the first voltage / current threshold.

[0008] Preferably, the intelligent monitoring and control unit further includes a sensing module for detecting the current and temperature of the distributed capacitor compensation device. The sensing module is connected to the controller, and the controller generates a second control command based on the acquired current and temperature information of the distributed capacitor compensation device. During the process of capacitive reactive power compensation by the distributed capacitor compensation device on the low-voltage side of the corresponding box-type transformer, if the current or temperature information of the distributed capacitor compensation device indicates overcurrent or overtemperature, a command is generated to disconnect the distributed capacitor compensation device from the low-voltage side of the corresponding box-type transformer.

[0009] Preferably, the distributed capacitor compensation device includes a capacitor bank and a switching switch, with the switching switch connected in series between the capacitor bank and the low-voltage side bus. The intelligent monitoring and control unit controls whether the distributed capacitor compensation device performs capacitive reactive power compensation on the low-voltage side of the corresponding box-type transformer by controlling the opening and closing of the switching switch based on control commands.

[0010] A distributed reactive power compensation method for the low-voltage side of a transformer substation based on wind speed detection includes the following steps; S1: Obtain wind speed information and voltage information of the low-voltage side busbar of the box-type transformer at the location of the wind turbine generator set; S2: Generates operating instructions based on wind speed and voltage information; S3: Controls the activation or deactivation of distributed capacitor compensation devices installed on the low-voltage side busbar of the box-type transformer according to the operation command.

[0011] Preferably, an activation command is generated when the wind speed information is lower than a first wind speed threshold and the voltage information is lower than a first voltage threshold. When the wind speed information is higher than the second wind speed threshold, or the voltage information is higher than the second voltage threshold, a cut-off command is generated; Wherein, the second wind speed threshold is greater than the first wind speed threshold, and the second voltage threshold is greater than the first voltage threshold.

[0012] Preferably, the capacity of the distributed capacitor compensation device configured on the low-voltage side of each box-type transformer is determined according to the following formula:

[0013] in, This refers to the compensation capacity of a single distributed capacitor compensation device. N represents the maximum total reactive power absorbed by the wind turbines in a wind farm under low wind speed conditions, and N is the number of box-type transformers.

[0014] Preferably, it also includes a protection step: real-time monitoring of the operating current and temperature of the distributed capacitor compensation device; when overcurrent or overtemperature occurs, the distributed capacitor compensation device is forcibly disconnected and an alarm message is issued; the protection step has a higher priority than the step of generating operating instructions based on wind speed and voltage information.

[0015] Compared with existing technologies, it has the following beneficial effects: This invention provides a distributed reactive power compensation system and method for the low-voltage side of a prefabricated transformer based on wind speed detection. It involves installing a distributed capacitor compensation device on the low-voltage busbar of each prefabricated transformer and setting up an intelligent monitoring and control unit to acquire wind speed and voltage information in real time. Based on this information, it generates operating commands to control the activation or deactivation of the distributed capacitor compensation device. Using this technical solution, 1. Using wind speed information as a feedforward criterion to achieve advanced response, overcoming the lag defect of traditional voltage deviation feedback control, and using voltage information for closed-loop verification to ensure compensation accuracy. 2. By moving the compensation point forward to the low-voltage side of the transformer, reactive power is compensated locally at each wind turbine terminal, avoiding line losses caused by long-distance transmission and reducing the investment cost of centralized SVG equipment. This effectively suppresses voltage drop under low wind speed conditions and improves the safety and economy of wind farm operation. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only preferred embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a block diagram of the distributed reactive power compensation system for the low-voltage side of a transformer substation based on wind speed detection, according to the present invention. Figure 2 This is a flowchart of the distributed reactive power compensation method for the low-voltage side of a transformer substation based on wind speed detection, according to the present invention.

[0017] In the diagram, there are: box-type transformer-1; distributed capacitor compensation device-2; capacitor bank-21; switching switch-22; intelligent monitoring and control unit-3; wind speed sensor-31; voltage / current detection module-32; controller-33; and communication module-34. Detailed Implementation

[0018] To better understand the structure, functional features, and advantages of the present invention, preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings: Example: like Figure 1 As shown, this invention provides a distributed reactive power compensation system for the low-voltage side of a prefabricated substation based on wind speed detection. It includes multiple prefabricated transformers 1, commonly referred to in the industry as prefabricated substations, which integrate electrical components such as transformers, high-voltage switchgear, and low-voltage switchgear into a single unit. These are widely used in wind farms, photovoltaic power plants, and other new energy power generation sites. In this application, the prefabricated transformers 1 are step-up type. The high-voltage side of each prefabricated transformer 1 is connected to the wind farm's collection line. This collection line collects the generated power from each wind turbine generator and transmits it to the wind farm's step-up substation, where it is further stepped up by the main transformer and then connected to the power grid. The low-voltage side power is connected to the corresponding wind turbine generator via low-voltage cables; the output voltage of the wind turbine generator is stepped up by the prefabricated transformer 1 and then sent to the collection line.

[0019] Distributed capacitor compensation device 2, installed on the low-voltage side busbar of each box-type transformer 1 and electrically connected to the low-voltage side busbar, is used to provide capacitive reactive power to the low-voltage side. The function of distributed capacitor compensation device 2 is to generate capacitive reactive power on the low-voltage side to compensate for the reactive power demand of wind turbine generators. Wind turbine generators in wind farms typically use doubly-fed asynchronous generators or permanent magnet synchronous generators. During power generation, they need to absorb reactive power from the grid to establish a magnetic field. Insufficient reactive power will lead to a decrease in the power factor, increased line losses, and even affect voltage stability. After distributed capacitor compensation device 2 is put into operation, capacitor bank 21 injects capacitive reactive current into the low-voltage side busbar, providing reactive power support to the wind turbine generators nearby, thereby reducing the flow of reactive power on long-distance transmission lines, reducing line losses, and improving voltage stability. Each box-type transformer 1 is equipped with a low-voltage busbar on its low-voltage side. The electrical energy generated by the wind turbine generator is input through the low-voltage side of the box-type transformer 1, stepped up, and then output from the high-voltage side to the collection line. The distributed capacitor compensation device 2 is installed at the low-voltage busbar of the box-type transformer 1. Its physical installation location can be located inside the low-voltage switchgear of the box-type transformer 1, or it can be located outside the box-type transformer 1 and close to the low-voltage busbar.

[0020] The distributed capacitance compensation device 2 includes a capacitor bank 21 and a switching switch 22. The capacitor bank 21 consists of multiple capacitor units and is used to provide capacitive reactive power to the low-voltage side. The switching switch 22 is connected in series between the capacitor bank 21 and the low-voltage side busbar. That is, one end of the switching switch 22 is connected to the low-voltage side busbar, and the other end is connected to one end of the capacitor bank 21. The other end of the capacitor bank 21 is connected to the neutral line, ground line, or another phase busbar, thus forming a complete electrical circuit. By closing or opening the switching switch 22, the capacitor bank 21 is controlled to be connected to the low-voltage side busbar, thereby realizing the input or output of reactive power.

[0021] The switching switch 22 can be a thyristor switch, a composite switch, or an AC contactor. This application uses a thyristor switch, which has the advantage of zero-crossing switching, enabling connection or disconnection near the voltage zero-crossing point, thereby effectively suppressing inrush current and operational overvoltage generated when the capacitor is connected, making it suitable for operating conditions requiring frequent switching. The switching switch 22 performs connection or disconnection operations accordingly based on the type of instruction received. When the switching switch 22 receives a connection instruction, its internal main circuit closes, connecting the capacitor bank 21 to the low-voltage side bus, and the capacitor bank 21 provides capacitive reactive power to the low-voltage side; when the switching switch 22 receives a disconnection instruction, its internal main circuit opens, disconnecting the capacitor bank 21 from the low-voltage side bus, and the capacitor bank 21 stops outputting reactive power.

[0022] The intelligent monitoring and control unit 3 is electrically connected to each distributed capacitor compensation device 2. It is used to obtain wind speed information and low-voltage side bus voltage information at the location of each wind turbine generator set, and generate operation commands based on the wind speed information and voltage information to control the activation or deactivation of the distributed capacitor compensation device 2.

[0023] The intelligent monitoring and control unit 3 includes a wind speed sensor 31, a voltage detection module 32, and a controller 33. The wind speed sensor 31 and the voltage detection module 32 are respectively connected to the controller 33. The sampling end of the voltage detection module 32 is connected to the low-voltage side bus of the box-type transformer 1.

[0024] The wind speed sensor 31 is installed at the nacelle of the wind turbine generator or the weather mast to detect the wind speed at the location of the wind turbine generator in real time and transmit the wind speed information to the controller 33. The wind speed sensor 31 can be a mechanical anemometer or an ultrasonic anemometer. The wind speed sensor 31 in this application uses an ultrasonic anemometer, which has no mechanical moving parts, high accuracy and long life.

[0025] The voltage detection module 32 is used to collect voltage information from the low-voltage side bus in real time, and converts the collected voltage information into electrical information that can be recognized by the controller 33 before transmitting it to the controller 33. The voltage detection module 32 can be a voltage transformer, which proportionally transforms the high voltage into a low voltage, and then sends the result to the controller 33 via an A / D converter. The specific connection method between the voltage detection module 32 and the low-voltage side bus is as follows: the high-voltage side of the voltage transformer is connected in parallel between the three-phase line and the neutral line or between phase lines of the low-voltage side bus; the low-voltage side of the voltage transformer is connected to the analog input interface of the controller 33 via a shielded cable.

[0026] The controller 33 is the core logic processing component of the intelligent monitoring and control unit 3. It receives information collected by the wind speed sensor 31 and the voltage detection module 32, performs logical judgments according to the preset control strategy, and generates corresponding on / off commands to control the switching of the distributed capacitor compensation device 2. The controller 33 can be a programmable logic controller (PLC), which mainly includes a central processing unit (CPU), memory, input interface, output interface, and communication interface. The CPU is responsible for executing user programs to perform logical and arithmetic operations. The memory is used to store system programs and user programs. The input interface is used to receive external information (such as wind speed information and voltage information). The output interface is used to output control commands to the switching switch 22. The communication interface is used to connect with the communication module 34 to realize data interaction with the wind farm monitoring system.

[0027] The intelligent monitoring and control unit 3 also includes a sensing module for detecting the current and temperature of the distributed capacitor compensation device 2, which is connected to the controller 33. The sensing module includes a current transformer connected in series in the capacitor bank 21 circuit and a temperature sensor attached to the surface of the capacitor bank 21 casing, used to detect the operating current and operating temperature of the distributed capacitor compensation device 2, respectively. During the process of the distributed capacitor compensation device 2 performing capacitive reactive power compensation on the low-voltage side of the corresponding box-type transformer 1, when the current information detected by the sensing module indicates that the current value exceeds a preset multiple of the capacitor's rated current, such as 1.3 times, or the temperature information indicates that the temperature value exceeds the capacitor's maximum allowable operating temperature, such as 65℃, the controller 33 generates a forced disconnection command to disconnect the distributed capacitor compensation device 2 from the low-voltage side of the corresponding box-type transformer 1, and sends a fault alarm signal to the wind farm control center, thereby achieving overcurrent and overheat protection for the distributed capacitor compensation device 2.

[0028] The output of controller 33 is connected to the control electrode of switching switch 22 via a drive circuit. The control commands generated by controller 33 are converted into corresponding switch drive signals by the drive circuit, controlling switching switch 22 to perform closing or opening operations. When controller 33 generates an activation command, the drive circuit triggers switching switch 22 to close, connecting capacitor bank 21 to the low-voltage side bus, and distributed capacitor compensation device 2 begins to provide capacitive reactive power to the low-voltage side of box transformer 1. When controller 33 generates a deactivation command, the drive circuit controls switching switch 22 to open, disconnecting capacitor bank 21 from the low-voltage side bus, and distributed capacitor compensation device 2 stops outputting reactive power. When switching switch 22 uses a thyristor switch, controller 33 detects the voltage zero-crossing point and the current zero-crossing point, controlling switching switch 22 to complete the activation operation near the voltage zero-crossing point and the deactivation operation near the current zero-crossing point, thereby effectively suppressing the surge current generated when the capacitor is activated and the operating overvoltage generated when it is deactivated.

[0029] The intelligent monitoring and control unit 3 of this application also includes a communication module 34, which is connected to the controller 33 and used for data interaction with the wind farm monitoring system. The communication module 34 uses Ethernet. It uploads wind speed information, voltage information, and the current on / off status (on or off) of the distributed capacitor compensation device 2 obtained by the controller 33 to the wind farm monitoring system, enabling wind farm operators to remotely monitor the operating status and reactive power compensation status of each wind turbine generator. Simultaneously, the communication module 34 can also receive remote control commands issued by the wind farm monitoring system. The controller 33 then remotely controls the on / off operation of the distributed capacitor compensation device 2 according to these commands, achieving remote scheduling functionality.

[0030] As another embodiment, such as Figure 2As shown, the distributed reactive power compensation method for the low-voltage side of a transformer substation based on wind speed detection in this application includes the following steps; S1: Obtain wind speed information at the location of the wind turbine generator and voltage information of the low-voltage side busbar of the box-type transformer 1.

[0031] Specifically, wind speed sensors 31, installed at the nacelle or meteorological mast of the wind turbine generator, detect the wind speed at the location of the wind turbine generator in real time, generate wind speed information, and transmit it to the controller 33. Simultaneously, voltage detection module 32 collects the voltage information of the low-voltage side bus of the box-type transformer 1 in real time and transmits this voltage information to the controller 33. Both wind speed and voltage information are continuously sampled in real time. The controller 33 collects this information at a predetermined sampling period, for example, once every 100ms, and uses this information as input parameters for subsequent reactive power compensation decisions.

[0032] S2: Generates operating instructions based on wind speed and voltage information; A power-on command is generated when both wind speed and voltage information are below a first wind speed threshold and a first voltage threshold, respectively. The first wind speed threshold is used to determine whether the wind turbine is operating under low wind speed conditions. When the wind speed is below the first wind speed threshold, it indicates that the wind turbine is connected to the grid but its output power is low. In this case, wind turbines such as doubly-fed induction generators absorb relatively large amounts of reactive power from the grid, requiring capacitor input for compensation. When the voltage information is below the first voltage threshold, it indicates that the bus voltage is low, and capacitor input can simultaneously boost the voltage. Inputting compensation when both conditions are met avoids overvoltage caused by inputting capacitors when the voltage is already sufficient.

[0033] A disconnection command is generated when the wind speed information exceeds the second wind speed threshold or the voltage information exceeds the second voltage threshold. The second wind speed threshold is greater than the first wind speed threshold and is used to determine whether the wind turbine has entered the high wind speed operating range. When the wind speed is higher than the second wind speed threshold, it indicates good wind conditions and the unit's output power is already high. At this time, the unit may have entered the power limiting zone or no longer needs a large amount of reactive power support. Continuing to connect capacitors may lead to excess reactive power being fed back to the grid, so disconnection is necessary. The second voltage threshold is greater than the first voltage threshold. When the bus voltage has risen above the second voltage threshold, it indicates that the voltage has returned to the normal range. Continuing to connect capacitors may lead to overvoltage, so compensation needs to be disconnected.

[0034] The specific values ​​of the aforementioned first wind speed threshold, second wind speed threshold, first voltage threshold, and second voltage threshold can be set by those skilled in the art based on the actual operating conditions of the wind farm and the technical parameters of the selected wind turbine generator set. For example, for a doubly-fed asynchronous wind turbine generator set with a rated wind speed of 12 m / s, the first wind speed threshold can be set to 4 m / s and the second wind speed threshold can be set to 10 m / s; the voltage threshold can be set based on the rated voltage, with the first voltage threshold set to 0.95 times the rated voltage and the second voltage threshold set to 1.05 times the rated voltage.

[0035] The capacity of the distributed capacitor compensation device 2 configured on the low-voltage side of each box-type transformer 1 is determined according to the following formula:

[0036] in, This refers to the compensation capacity of a single distributed capacitor compensation device. N represents the maximum total reactive power absorbed by the wind turbines in a wind farm under low wind speed conditions, and N is the number of box-type transformers.

[0037] The reactive power is obtained by measuring or simulating the reactive power absorbed by each wind turbine from the grid under low wind speed conditions. The sum of the reactive power absorbed by each turbine is the maximum total reactive power. Since each box-type transformer 1 is independently equipped with a distributed capacitor compensation device 2 on its low-voltage side, and the wind turbine connected to each box-type transformer 1 has a basically the same capacity, the total reactive power demand is evenly distributed to each box-type transformer 1. That is, the compensation capacity of each distributed capacitor compensation device 2 is 1 / N of the maximum total reactive power.

[0038] The above-described equal-capacity configuration method applies to situations where all wind turbine generators in a wind farm are of the same specification. If the capacities of the wind turbine generators differ, those skilled in the art can also allocate unequal capacities based on the proportion of each generator's capacity in the total installed capacity of the wind farm, i.e.:

[0039] in, Let be the compensation capacity of the i-th distributed capacitor compensation device 2. Let i be the rated capacity of the i-th wind turbine generator. This represents the total installed capacity of the wind farm.

[0040] S3: Controls the activation or deactivation of the distributed capacitor compensation device installed on the low-voltage side busbar of box-type transformer 1 according to the operation command.

[0041] When controller 33 generates an on / off command, it sends the operating command to the control terminal of switching switch 22. Upon receiving an on command, switching switch 22 performs a closing operation, its internal main circuit is activated, connecting capacitor bank 21 to the low-voltage side bus and injecting capacitive reactive current into the low-voltage side to achieve local reactive power compensation. Upon receiving a off command, it performs a disconnecting operation, its internal main circuit is deactivated, disconnecting capacitor bank 21 from the low-voltage side bus and stopping reactive power compensation. Switch 22 preferably uses thyristor switches or composite switches to achieve zero-crossing switching of capacitor bank 21, suppressing inrush current and operational overvoltage, reducing impact on the power grid, and extending equipment lifespan.

[0042] Each distributed capacitor compensation device 2 is controlled independently and does not affect the others. The controller 33 generates independent operating commands for each distributed capacitor compensation device 2 based on the wind speed information of each wind turbine generator and the voltage information of each low-voltage side bus. The activation or deactivation of a single device does not affect the normal operation of other devices, thus realizing independent reactive power compensation and precise control of each unit.

[0043] As another embodiment, such as Figure 2 As shown, this application also includes a protection step: each distributed capacitor compensation device 2 is further equipped with a current detection module and a temperature detection module, which are used to detect the operating current and operating temperature of the capacitor bank 21 in real time, and transmit the detection information to the controller 33 in real time. The operating current and temperature of the distributed capacitor compensation device 2 are monitored in real time, and when overcurrent or overtemperature occurs, the distributed capacitor compensation device 2 is forcibly disconnected and an alarm message is issued; The protection steps take precedence over the steps that generate operating commands based on wind speed and voltage information. Even if the system determines whether to activate or remain activated based on wind speed and voltage information, controller 33 will still perform forced disconnection in case of overcurrent or overtemperature, ensuring equipment safety takes precedence over reactive power compensation needs. After forced disconnection, the system can only be reactivated after manual confirmation that the fault has been resolved and the system has been reset.

[0044] The working principle of the distributed reactive power compensation system for the low-voltage side of the transformer substation based on wind speed detection in this application is as follows: Wind speed sensor 31 detects wind speed in real time, and voltage detection module 32 collects low-voltage side bus voltage in real time. Both transmit the information to controller 33. Controller 33 determines whether reactive power compensation is needed based on the wind speed and voltage information according to a preset strategy. When it needs to be activated, a command is sent to close the switching switch 22, connecting capacitor bank 21 to the bus and injecting capacitive reactive current locally to reduce line losses and avoid delays in manual operation. When it needs to be deactivated, a command is sent to open the switching switch 22, disconnecting capacitor bank 21 to prevent overvoltage or reverse reactive power transmission. Each transformer substation is independently equipped with a compensation device, so a single unit failure does not affect other units, avoiding the risk of single-point failure in centralized compensation and improving system reliability. Communication module 34 uploads the operating status to the monitoring system in real time for remote monitoring and receives remote control commands to achieve remote switching. Dispatch can be completed without on-site inspection, reducing operation and maintenance costs and improving the level of intelligent management.

[0045] The working principle of the distributed reactive power compensation method for the low-voltage side of the box-type transformer based on wind speed detection is as follows: First, the wind speed information of the wind turbine generator location is obtained in real time through the wind speed sensor 31, and the voltage information of the low-voltage side bus of the box-type transformer 1 is obtained in real time through the voltage detection module 32. The controller 33 determines whether reactive power compensation is required under the current operating condition according to the received wind speed and voltage information and a preset control strategy. When the wind speed information is lower than the first wind speed threshold and the voltage information is lower than the first voltage threshold, an activation command is generated. When the wind speed information is higher than the second wind speed threshold or the voltage information is higher than the second voltage threshold, a deactivation command is generated. The switching switch 22 executes the closing command according to the received operating command. The controller 33 controls the capacitor bank 21 to connect to or disconnect the low-voltage side bus, thereby achieving local compensation of reactive power. Each distributed capacitor compensation device 2 is independently controlled and does not affect the others. During operation, the current detection module and temperature detection module monitor the operating current and temperature of the capacitor bank 21 in real time. When overcurrent or overtemperature occurs, the controller 33 forcibly disconnects the device and issues an alarm message. The protection step has a higher priority than the normal operation control step. The communication module 34 uploads the operating status to the wind farm monitoring system in real time and receives remote control commands to achieve remote scheduling, thereby achieving automatic, accurate, and local compensation of reactive power in the wind farm while ensuring system safety.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technology of the present invention without departing from the scope of the present invention are within the protection scope of the present invention.

Claims

1. A distributed reactive power compensation system for the low-voltage side of a prefabricated substation based on wind speed detection, characterized in that, include: Several box-type transformers (1), the high-voltage side of the box-type transformers (1) is connected to the wind farm collection line respectively, and the low-voltage side is electrically connected to the corresponding wind turbine generator set, for boosting the output voltage of the corresponding wind turbine generator set; Distributed capacitor compensation device (2) is installed on the low-voltage side bus of each of the box transformers (1) and is electrically connected to the low-voltage side bus of the box transformers (1) to provide capacitive reactive power to the low-voltage side of the box transformers (1) as needed. The intelligent monitoring and control unit (3) is electrically connected to each of the distributed capacitor compensation devices (2) and is used to obtain the wind speed information of the location of each wind turbine generator set and the voltage / current information of the low-voltage side bus of the box transformer (1), and generate control commands based on the wind speed information and the voltage / current information to control whether the distributed capacitor compensation device (2) performs capacitive reactive power compensation on the low-voltage side of the corresponding box transformer (1).

2. The distributed reactive power compensation system for the low-voltage side of a transformer substation based on wind speed detection according to claim 1, characterized in that, The intelligent monitoring and control unit (3) includes a wind speed sensor (31), a voltage / current detection module (32) and a controller (33). The wind speed sensor (31) and the voltage / current detection module (32) are respectively connected to the controller (33). The sampling end of the voltage / current detection module (32) is connected to the low-voltage side bus of the box transformer (1).

3. Based on the received wind speed information and the voltage / current information on the low-voltage side of the box-type transformer (1), the controller generates a first control command, including: When the wind speed is lower than the first wind speed threshold and the voltage / current is higher than the first voltage / current threshold, or when the wind speed is lower than the second wind speed threshold and the voltage / current is higher than the first voltage / current threshold, an instruction is generated for the distributed capacitor compensation device (2) to maintain the current state. When the wind speed is lower than the first wind speed threshold and the voltage / current is lower than the first voltage / current threshold, or when the wind speed is lower than the second wind speed threshold and the voltage / current is lower than the first voltage / current threshold, an instruction is generated for the distributed capacitor compensation device (2) to perform capacitive reactive power compensation on the low-voltage side of the corresponding box transformer (1). When the wind speed is higher than the second wind speed threshold, or the voltage / current is higher than the second voltage / current threshold, an instruction is generated to disconnect the distributed capacitor compensation device (2) from the low-voltage side of the corresponding box transformer (1) for capacitive reactive power compensation. The second wind speed threshold is greater than the first wind speed threshold, and the second voltage / current threshold is greater than the first voltage / current threshold.

4. The distributed reactive power compensation system for the low-voltage side of a transformer substation based on wind speed detection according to claim 2, characterized in that, The intelligent monitoring and control unit (3) further includes a sensing module for detecting the current and temperature of the distributed capacitance compensation device (2). The sensing module is connected to the controller, and the controller generates a second control command based on the acquired current and temperature information of the distributed capacitance compensation device (2): During the process of capacitive reactive power compensation of the low-voltage side of the corresponding box transformer (1) by the distributed capacitor compensation device (2), if the current information or temperature information of the distributed capacitor compensation device (2) indicates overcurrent or overtemperature, an instruction is generated to disconnect the capacitive reactive power compensation of the low-voltage side of the corresponding box transformer (1) by the distributed capacitor compensation device (2).

5. The distributed reactive power compensation system for the low-voltage side of a transformer substation based on wind speed detection according to claim 1, characterized in that, The distributed capacitor compensation device (2) includes a capacitor bank (21) and a switching switch (22). The switching switch (22) is connected in series between the capacitor bank (21) and the low-voltage side bus. The intelligent monitoring and control unit (3) controls whether the distributed capacitor compensation device (2) performs capacitive reactive power compensation on the low-voltage side of the corresponding box transformer (1) by controlling the opening and closing of the switching switch (22) based on control commands.

6. A distributed reactive power compensation method for the low-voltage side of a prefabricated substation based on wind speed detection, characterized in that, The distributed reactive power compensation system for the low-voltage side of the transformer substation based on wind speed detection, as described in claims 1-4, includes the following steps; S1: Obtain wind speed information at the location of the wind turbine generator and voltage / current information of the low-voltage side busbar of the box transformer (1); S2: Generate an operation command based on the wind speed information and the voltage / current information; S3: Control the activation or deactivation of the distributed capacitor compensation device installed on the low-voltage side busbar of the box transformer (1) according to the operation command.

7. The distributed reactive power compensation method for the low-voltage side of a transformer substation based on wind speed detection according to claim 5, characterized in that, When the wind speed information is lower than the first wind speed threshold and the voltage information is lower than the first voltage threshold, an input command is generated; When the wind speed information is higher than the second wind speed threshold, or the voltage information is higher than the second voltage threshold, a cut-off command is generated; Wherein, the second wind speed threshold is greater than the first wind speed threshold, and the second voltage threshold is greater than the first voltage threshold.

8. The distributed reactive power compensation method for the low-voltage side of a transformer substation based on wind speed detection according to claim 5, characterized in that, The capacity of the distributed capacitor compensation device (2) configured on the low-voltage side of each of the aforementioned box-type transformers (1) is determined according to the following formula: ； in, This refers to the compensation capacity of a single distributed capacitor compensation device. N represents the maximum total reactive power absorbed by the wind turbines in a wind farm under low wind speed conditions, and N is the number of box-type transformers.

9. The distributed reactive power compensation method for the low-voltage side of a transformer substation based on wind speed detection according to claim 5, characterized in that, It also includes a protection step: real-time monitoring of the operating current and temperature of the distributed capacitor compensation device (2), and when overcurrent or overtemperature occurs, the distributed capacitor compensation device (2) is forcibly disconnected and an alarm message is issued. The priority of the protection step is higher than the step of generating the operating command based on the wind speed information and the voltage information.

Images