Offshore wind power flexible direct current transmission power limiting control system and method

Abstract

The application discloses a kind of offshore wind power flexible DC sending power limiting control system and method, belong to flexible DC wind power control field, offshore wind power flexible DC sending power limiting control system, the system includes: flexible DC control device, stability device and flexible DC power reduction detection device, flexible DC control device respectively with stability device, flexible DC power reduction detection device communication connection;Stability device is used to set on land grid side, and the power reduction value needed by offshore power grid is calculated;Flexible DC power reduction detection device is used to calculate the power reduction value needed by offshore wind farm.Compared with the original scheme, after the flexible DC control device of offshore converter station side receives the power reduction value, directly send control data to energy management platform, no longer need to issue control instruction from onshore dispatching station to offshore converter station, then to offshore wind farm energy management platform control instruction, so as to speed up the control speed of offshore wind power flexible DC power.

Description

Technical Field

[0001] This invention belongs to the field of wind power control, and in particular relates to a control system and method for limiting the power output of flexible DC transmission from offshore wind power. Background Technology

[0002] Flexible DC transmission has advantages such as no need for additional reactive power compensation, no commutation failure problem, power supply for passive systems, and suitability for constructing multi-terminal DC systems. With the increase in the capacity and distance of offshore wind farms, flexible DC transmission has become the mainstream solution for transmitting and connecting large-capacity offshore wind power in deep sea to the grid.

[0003] The existing flexible DC transmission control system for offshore wind power works as follows: When the onshore dispatch station receives an instruction from the onshore power grid or offshore wind farm to reduce power output, the onshore dispatch station obtains power data from both the onshore power grid and the offshore wind farm. The dispatch station then calculates the specific power reduction value based on this data and transmits the value level by level to the offshore energy control station. The offshore energy control station then controls the power generation of the wind turbines based on the magnitude of the power reduction. However, the dispatch station's process of retrieving the relevant data and calculating the specific power reduction value takes several seconds, and then transmitting the power value level by level to the offshore energy control station also takes several seconds. For flexible DC transmission power, the control speed requirement is in the millisecond range; the existing control rate is too slow and cannot effectively control DC faults.

[0004] In summary, when power reduction is required, the existing offshore wind power flexible DC transmission power control process is slow and inefficient. Summary of the Invention

[0005] The purpose of this invention is to provide a power limiting control system and method for offshore wind power flexible DC transmission, so as to solve the technical problems of slow speed and low efficiency in the existing offshore wind power flexible DC transmission power control process when power reduction is required.

[0006] To achieve the above objectives, the technical solution of the flexible DC power transmission limitation control system and method for offshore wind power provided by the present invention is as follows:

[0007] A flexible DC power transmission limiting and control system for offshore wind power includes: a flexible DC control device, a stabilization device, and a flexible DC power reduction detection device. The flexible DC control device is communicatively connected to the stabilization device and the flexible DC power reduction detection device, respectively.

[0008] The stabilization device is installed on the onshore power grid side to detect changes in the onshore power grid load, and when an emergency reduction in the onshore power grid load occurs, it acquires the onshore power grid power data, calculates the required power reduction value for the offshore power grid, and sends the power reduction value to the flexible DC control device.

[0009] The flexible DC power reduction detection device is installed on the offshore converter station side to detect the status of the offshore converter station, and when an emergency power reduction condition occurs at the offshore converter station, it acquires the power data of the offshore wind farm, calculates the required power reduction value of the offshore wind farm, and sends the power reduction value to the flexible DC control device.

[0010] The flexible DC control device is installed on the offshore converter station side to compare the power reduction values ​​sent by the stabilization device and the detection device, calculate the required power value of the offshore wind farm based on the maximum value, and send the required power value to the offshore wind farm energy management platform. The offshore wind farm energy management platform controls the offshore wind turbines to reduce power according to the required power value.

[0011] The beneficial effects are as follows: By using the stabilization device installed on the onshore power grid side to detect the load status of the onshore power grid and calculate the power reduction value when there is a power reduction requirement, and by using the flexible DC control device installed on the offshore converter station side to detect the working status of the offshore converter and calculate the corresponding power reduction value when there is a power reduction requirement, compared with the current method, this invention does not require the dispatch station to obtain data from the offshore converter station remotely and calculate the power reduction value, nor does it require obtaining data from the onshore power grid to calculate the power reduction value, and can quickly and accurately obtain the corresponding power reduction value.

[0012] Meanwhile, after receiving the power reduction value, the flexible DC control device on the offshore converter station side directly sends control data to the offshore wind farm energy management platform. Compared with the original scheme, it is no longer necessary to send control commands from the onshore dispatch station to the offshore converter station and then to the offshore wind farm energy management platform, thereby speeding up the control speed of the flexible DC power of offshore wind power.

[0013] As a further improvement, emergency load reduction of onshore power grid refers to: the load reduction of onshore power grid within a set time exceeds the load threshold; emergency power reduction refers to: the failure of offshore converter station to disconnect due to connection transformer failure, flexible DC voltage reduction operation, abnormal valve cooling equipment or operation of flexible DC protection device requiring emergency power reduction.

[0014] The beneficial effects are: the load stabilization device determines whether the load needs to be urgently reduced by using load thresholds and set time intervals, improving the accuracy of load reduction assessment. The flexible DC power reduction detection device identifies operating conditions in offshore wind farms, such as connection transformer failures, flexible DC voltage reduction operation, valve cooling equipment malfunctions, or flexible DC protection device activation requiring emergency power reduction, to determine whether it is necessary to reduce the power of the offshore wind farm. By reducing power, the faults in the offshore converter station are mitigated, ensuring the safe operation of the offshore converter station.

[0015] As a further improvement, the offshore wind farm energy management platform reduces power output by shutting down a corresponding number of wind turbines.

[0016] The beneficial effect is that the power injected into the onshore power grid is positively correlated with the power generation of the offshore wind farm, and the power generation of the offshore wind farm is determined by the number of wind turbines connected to the grid. Therefore, the power reduction requirements of the onshore power grid and the offshore wind farm can be achieved by disconnecting the wind turbines connected to the grid.

[0017] As a further improvement, the flexible DC control device and the stabilization device communicate via gigabit fiber optic cable.

[0018] The benefits are that gigabit fiber optics offer faster communication speeds compared to existing 100 Mbps fiber optics, facilitating the millisecond-level control speed required for flexible DC transmission.

[0019] This invention also discloses a method for limiting and controlling the power output of flexible DC transmission for offshore wind power, comprising the following steps: using a stabilization device installed on the onshore power grid side to detect changes in the onshore power grid load; when the onshore power grid load drops urgently, calculating the required power reduction value for the offshore power grid based on the onshore power grid power data and sending the power reduction value; using a flexible DC power reduction detection device installed on the offshore converter station side to detect the operating status of the offshore converter station; when an emergency power reduction condition occurs at the offshore converter station, calculating the required power reduction value for the offshore wind farm based on the offshore wind farm power data and sending the power reduction value; receiving the power reduction values ​​sent by the stabilization device and the flexible DC power reduction detection device, calculating the required power value for the offshore wind farm based on the maximum value among them, and sending the required power value to the offshore wind farm energy management platform; the offshore wind farm energy management platform controlling the power reduction of the offshore wind turbines based on the required power value.

[0020] The beneficial effects are: when the onshore power grid side's stabilization device detects a power reduction demand, it calculates and sends the specific value of the power reduction; when the offshore converter station's flexible DC power reduction detection device detects a power reduction demand, it calculates and sends the specific value of the power reduction. The control terminal receives the two specific values ​​of the power reduction, and the control terminal no longer needs to retrieve relevant data for calculation, saving control time and improving the efficiency of power reduction control.

[0021] As a further improvement, emergency load reduction of onshore power grid refers to: the load reduction of onshore power grid within a set time exceeds the load threshold; emergency power reduction refers to: the failure of offshore converter station to disconnect due to connection transformer failure, flexible DC voltage reduction operation, abnormal valve cooling equipment or operation of flexible DC protection device requiring emergency power reduction.

[0022] The beneficial effect is that by using load thresholds and set times to determine whether the load is urgently reduced, the accuracy of judging the load reduction situation is improved. When offshore wind farms experience situations such as connection transformer failure and outage, flexible DC step-down operation, valve cooling equipment malfunction, or flexible DC protection device activation requiring emergency power reduction, power reduction is necessary to alleviate the fault.

[0023] As a further improvement, the offshore wind farm energy management platform reduces power output by shutting down a corresponding number of wind turbines.

[0024] The beneficial effect is that the power injected into the onshore power grid is positively correlated with the power generation of the offshore wind farm, and the power generation of the offshore wind farm is determined by the number of wind turbines connected to the grid. Therefore, the power reduction requirements of the onshore power grid and the offshore wind farm can be achieved by disconnecting the wind turbines connected to the grid. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the flexible DC power transmission limiting control system for offshore wind power according to the present invention;

[0026] Figure 2 This is a flowchart of the offshore wind power flexible DC transmission power limiting control method of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Example of a flexible DC power transmission limiting control system for offshore wind power:

[0029] like Figure 1 As shown, the offshore wind power flexible DC transmission power limiting control system includes: a flexible DC control device, a stabilization device, and a flexible DC power reduction detection device. The flexible DC control device is communicatively connected to both the stabilization device and the flexible DC power reduction detection device. The flexible DC control device and the stabilization device communicate via gigabit fiber optic cable. The offshore wind farm energy management platform controls the 66kV offshore wind turbines. This gigabit fiber optic cable is an IEC61850 gigabit fiber optic cable.

[0030] This stabilization device is installed on the onshore power grid side. When an emergency load reduction is detected, it acquires the onshore power grid's power data, calculates the power reduction command ΔPa, and sends it to the flexible DC control device. An emergency load reduction occurs when the load decreases by a percentage exceeding a set threshold within a short period.

[0031] The flexible DC power reduction detection device is installed on the offshore converter station side. When an emergency power reduction condition is detected at the offshore wind farm, it acquires the offshore wind farm's power data, calculates the power reduction command ΔPb, and sends it to the flexible DC control device. Emergency power reduction conditions detected at the offshore wind farm include: connection transformer failure and disconnection at the offshore converter station, flexible DC voltage reduction operation, valve cooling equipment malfunction, and activation of the flexible DC protection device requiring emergency power reduction.

[0032] The flexible DC control device is used to receive power reduction commands △Pa and △Pb, compare the magnitudes of △Pa and △Pb, obtain the current power command Pref required by the offshore wind farm by subtracting the maximum value of the current offshore wind farm power, and send the required power command Pref to the offshore wind farm energy management platform, where the power command is the corresponding power value.

[0033] The offshore wind farm energy management platform controls the offshore wind turbines to reduce power according to the power command Pref required by the offshore wind farm, and further reduces power by controlling the offshore wind farm to shut down a corresponding number of wind turbines.

[0034] The flexible DC control device acquires the specific power reduction values ​​ΔPa and ΔPb sent by the stabilization device and the flexible DC power reduction detection device. Compared with the existing scheme, the dispatch station no longer needs to retrieve relevant data to calculate the specific power reduction value, saving the control time of the flexible DC control device and improving the efficiency of power reduction control. The flexible DC control device calculates the required power based on the maximum value of the current power reduction demand received, so as to meet all power reduction requirements. The offshore wind farm energy management platform controls the power reduction of offshore wind turbines based on the received required power value. Wind turbines are key equipment for power generation in offshore wind farms, and reducing the power of wind turbines achieves the requirement of reducing offshore power generation. In this system, the communication distance between the stabilization device on the onshore grid side and the flexible DC control device on the offshore converter station side is relatively long. Therefore, IEC61850 gigabit fiber optic communication is used to improve the control efficiency of the control system. The communication between devices in the entire control system is either short-distance communication or gigabit fiber optic communication, realizing the millisecond-level control speed required for flexible DC transmission.

[0035] Example of a method for limiting and controlling the power output of flexible DC transmission from offshore wind power:

[0036] like Figure 2As shown, the offshore wind power flexible DC transmission power limiting control method includes the following steps: 1) Detecting changes in onshore grid load using a stabilization device installed on the onshore grid side; 2) Calculating the required power reduction value for the offshore grid based on onshore grid power data and sending the power reduction value when the onshore grid load drops urgently; 3) Detecting the operating status of the offshore converter station using a flexible DC power reduction detection device installed on the offshore converter station side; 4) Calculating the required power reduction value for the offshore wind farm based on offshore wind farm power data and sending the power reduction value when an emergency power reduction condition occurs at the offshore converter station; 5) Receiving the power reduction values ​​sent by the stabilization device and the flexible DC power reduction detection device, calculating the required power value for the offshore wind farm based on the maximum value, and sending the required power value to the offshore wind farm energy management platform; 6) Controlling the power reduction of the offshore wind turbines based on the required power value. This embodiment refers to the embodiment of the offshore wind power flexible DC transmission power limiting control system, and will not be repeated here.

[0037] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flexible DC transmission power limiting control system for offshore wind power, characterized in that, The system includes: a flexible DC control device, a stabilization device, and a flexible DC power reduction detection device, wherein the flexible DC control device is communicatively connected to the stabilization device and the flexible DC power reduction detection device, respectively. The stabilization device is installed on the onshore power grid side to detect changes in the onshore power grid load, and when an emergency reduction in the onshore power grid load occurs, it acquires the onshore power grid power data, calculates the required power reduction value for the offshore power grid, and sends the power reduction value to the flexible DC control device. The flexible DC power reduction detection device is installed on the offshore converter station side to detect the status of the offshore converter station, and when an emergency power reduction condition occurs at the offshore converter station, it acquires the power data of the offshore wind farm, calculates the required power reduction value of the offshore wind farm, and sends the power reduction value to the flexible DC control device. The flexible DC control device is installed on the offshore converter station side to compare the power reduction values ​​sent by the stabilization device and the detection device, calculate the required power value of the offshore wind farm based on the maximum value, and send the required power value to the offshore wind farm energy management platform. The offshore wind farm energy management platform controls the offshore wind turbines to reduce power based on the required power value. Emergency load reduction of onshore power grid refers to: the load reduction of the onshore power grid within a set time exceeds the load threshold; Emergency power reduction conditions refer to situations where the offshore converter station experiences a connection failure and disconnection, flexible DC voltage reduction operation, valve cooling equipment malfunctions, or flexible DC protection device activation, requiring an emergency power reduction.

2. The offshore wind power flexible DC transmission power limiting control system according to claim 1, characterized in that, The flexible DC control device and the stabilization device communicate via gigabit fiber optic cable.

3. The offshore wind power flexible DC transmission power limiting control system according to claim 1, characterized in that, Offshore wind farm energy management platforms reduce power output by shutting down a corresponding number of wind turbines.

4. The offshore wind power flexible DC transmission power limiting control system according to any one of claims 1-3, characterized in that, The flexible DC control device communicates with the offshore wind farm energy management platform via gigabit fiber optic cable.

5. A method for limiting and controlling the power output of flexible DC transmission from offshore wind power, characterized in that, Includes the following steps: The system uses a stabilization device installed on the onshore power grid side to detect changes in the onshore power grid load. When the onshore power grid load drops urgently, it calculates the required power reduction value for the offshore power grid based on the onshore power grid power data and sends the power reduction value. The working status of the offshore converter station is detected by a flexible DC power reduction detection device installed on the offshore converter station side. When an emergency power reduction condition occurs at the offshore converter station, the required power reduction value of the offshore wind farm is calculated based on the power data of the offshore wind farm and the power reduction value is sent. The system receives the power reduction values ​​sent by the stabilization device and the flexible DC power reduction detection device, calculates the required power value of the offshore wind farm based on the maximum value, and sends the required power value to the offshore wind farm energy management platform. The offshore wind farm energy management platform controls the power reduction of the offshore wind turbines based on the required power value. Emergency load reduction of onshore power grid refers to: the load reduction of the onshore power grid within a set time exceeds the load threshold; Emergency power reduction conditions refer to situations where the offshore converter station experiences a connection failure and disconnection, flexible DC voltage reduction operation, valve cooling equipment malfunctions, or flexible DC protection device activation, requiring an emergency power reduction.

6. The offshore wind power flexible DC transmission power limiting control method according to claim 5, characterized in that, Offshore wind farm energy management platforms reduce power output by shutting down a corresponding number of wind turbines.

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