Wind farm start-up auxiliary power supply system

Abstract

The application discloses a wind farm starting auxiliary power supply system, comprising: an auxiliary power supply module, the auxiliary power supply module being connectable with an external wind driven generator, the auxiliary power supply module being used for generating alternating current for assisting the starting of the external wind driven generator; and a feedback control module, an input end of the feedback control module being connected with an output end of the auxiliary power supply module, an output end of the feedback control module being connected with a control end of the auxiliary power supply module, the feedback control module being used for adjusting the size of output voltage and / or current of the auxiliary power supply module. The auxiliary power supply module generates alternating current suitable for the starting of the wind driven generator and transmits the alternating current to the wind driven generator, so as to provide alternating current support for assisting the starting of the wind driven generator. When the wind driven generator is completed starting, the feedback control module controls the auxiliary power supply module to reduce the output current to zero, that is, the auxiliary power supply module enters a standby state, and this is favorable for reducing the loss of the auxiliary power supply module and the overall system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind farms, in particular to a wind farm starting auxiliary power supply system. BACKGROUND

[0002] With the development of wind power generation technology, compared with land wind farms, offshore wind farms do not occupy land resources, and the sea wind speed is higher, the single machine capacity of offshore wind turbine generators is larger, and the annual utilization hours are higher, therefore, offshore wind farms are an important development field of wind power generation, and offshore wind power projects are gradually developing towards deep sea and open sea.

[0003] Offshore wind farms are integrated into the power grid, and due to the distance of offshore wind farms from the land, the traditional AC transmission scheme cannot meet the power output of large-scale offshore wind farms in the open sea, thereby limiting the large-scale development of offshore wind farms. Drawing on the experience of the fastest developing region in Europe, DC transmission technology has become the only optional scheme for power output of deep sea and open sea wind power generation.

[0004] Based on the distributed DC transmission of series uncontrolled converter stations, the system cost and operation loss are greatly reduced, the system reliability is improved, and the development demand of deep and open sea wind power is greatly adapted. Due to the configuration of series uncontrolled converters on the sea, the system cannot provide starting energy for the wind farm through the DC submarine cable, and needs to additionally configure a wind farm starting auxiliary power supply, and needs to properly regulate and control the auxiliary power supply. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a wind farm starting auxiliary power supply system which can feedback control module to control the auxiliary power supply module to adjust the output power and reduce the output current after the external wind turbine completes the starting, so as to reduce the loss.

[0006] The wind farm starting auxiliary power supply system according to the present application comprises: an auxiliary power supply module, which can be connected with an external wind turbine, and is used to generate AC power for assisting the starting of the external wind turbine; a feedback control module, the input end of which is connected with the output end of the auxiliary power supply module, the output end of which is connected with the control end of the auxiliary power supply module, and the feedback control module is used to adjust the size of the output voltage and / or current of the auxiliary power supply module.

[0007] The wind farm starting auxiliary power supply system according to the embodiment of the present application has at least the following beneficial effects: the auxiliary power supply module generates AC power suitable for starting the wind driven generator and transmits the AC power to the wind driven generator to provide AC power support for starting the wind driven generator. After the wind driven generator starts to generate power, the AC voltage between the auxiliary power supply module and the wind driven generator increases, the feedback control module detects and controls the auxiliary power supply module according to the AC voltage, so that the auxiliary power supply module adjusts the output power to reduce the size of the output current. When the wind driven generator completes the starting, the feedback control module controls the auxiliary power supply module to reduce the output current to zero, that is, the auxiliary power supply module enters the standby state, which is beneficial to reducing the loss of the auxiliary power supply module and the overall system.

[0008] According to some embodiments of the present application, the feedback control module comprises a detection unit and a vector control unit, the detection unit is connected with the output end of the auxiliary power supply module, the input end of the vector control unit is connected with the detection unit, and the output end of the vector control unit is connected with the auxiliary power supply module.

[0009] According to some embodiments of the present application, the vector control unit comprises a coordinate conversion unit, a comparison operation unit and an inverse coordinate conversion unit, the input end of the coordinate conversion unit is connected with the detection unit, the coordinate conversion unit is used to calculate the voltage value and / or current value in the DQ coordinate system according to the voltage value and / or current value of the AC power, the output end of the coordinate conversion unit is connected with the input end of the comparison operation unit, the comparison operation unit is used to compare the voltage value and / or current value in the DQ coordinate system with the preset reference value to calculate the control quantity, the output end of the comparison operation unit is connected with the input end of the inverse coordinate conversion unit, the inverse coordinate conversion unit is used to calculate the voltage control component and / or current control component according to the control quantity, and the output end of the inverse coordinate conversion unit is connected with the auxiliary power supply module, so that the auxiliary power supply module adjusts the size of the output voltage and / or current according to the voltage control component and / or current control component.

[0010] According to some embodiments of the present application, the comparison operation unit comprises a D-axis voltage PI controller and a Q-axis voltage PI controller, the coordinate conversion unit is provided with a D-axis voltage output end and a Q-axis voltage output end; the first input end of the D-axis voltage PI controller is connected with the detection unit or the D-axis voltage output end, the second input end of the D-axis voltage PI controller receives a first preset reference voltage value, and the output end of the D-axis voltage PI controller is connected with the inverse coordinate conversion unit; the first input end of the Q-axis voltage PI controller is connected with the detection unit or the Q-axis voltage output end, the second input end of the Q-axis voltage PI controller receives a second preset reference voltage value, and the output end of the Q-axis voltage PI controller is connected with the inverse coordinate conversion unit.

[0011] According to some embodiments of the present application, the comparison operation unit further comprises a D-axis current PI controller and a Q-axis current PI controller, and the coordinate conversion unit is provided with a D-axis current output end and a Q-axis current output end; a first input end of the D-axis current PI controller is connected with an output end of the D-axis voltage PI controller, a second input end of the D-axis current PI controller is connected with the D-axis current output end, and an output end of the D-axis current PI controller is connected with the inverse coordinate conversion unit; a first input end of the Q-axis current PI controller is connected with an output end of the Q-axis voltage PI controller, a second input end of the Q-axis current PI controller is connected with the Q-axis current output end, and an output end of the Q-axis current PI controller is connected with the inverse coordinate conversion unit.

[0012] According to some embodiments of the present application, the comparison operation unit further comprises a D-axis limiting unit and a Q-axis limiting unit; an output end of the D-axis voltage PI controller is connected with an input end of the D-axis limiting unit, an output end of the D-axis limiting unit is connected with a first input end of the D-axis current PI controller, and the D-axis limiting unit is used for limiting an output value of the D-axis voltage PI controller in a preset range; an output end of the Q-axis voltage PI controller is connected with an input end of the Q-axis limiting unit, an output end of the Q-axis limiting unit is connected with a first input end of the Q-axis current PI controller, and the Q-axis limiting unit is used for limiting an output value of the Q-axis voltage PI controller in a preset range.

[0013] According to some embodiments of the present application, the comparison operation unit further comprises a linkage unit, an input end of the linkage unit is connected with an output end of the Q-axis voltage PI controller, an output end of the linkage unit is connected with a first input end of the Q-axis current PI controller, and a control end of the linkage unit is connected with an output end of the D-axis voltage PI controller, and the linkage unit is used for limiting an output value range of the Q-axis voltage PI controller according to an output value of the D-axis voltage PI controller.

[0014] According to some embodiments of the present application, the auxiliary power supply module comprises a power transmission line and a power electronic device or a load-regulated voltage transformer, an input end of the power electronic device is connected with an external power grid or an external direct-current power transmission system, an input end of the load-regulated voltage transformer is connected with the external power grid, an output end of the power electronic device or an output end of the load-regulated voltage transformer is connected with an external wind turbine through the power transmission line, and a control end of the power electronic device or a control end of the load-regulated voltage transformer is connected with the feedback control module.

[0015] According to some embodiments of the present application, the power electronic device comprises a back-to-back converter, an input end of the back-to-back converter is connected with an external power grid, an output end of the back-to-back converter is connected with an external wind power generator through the power transmission line, and a control end of the back-to-back converter is connected with the feedback control module.

[0016] According to some embodiments of the present application, the power electronic device comprises an inverter, an input end of the inverter is connected with an external DC power transmission system, an output end of the inverter is connected with an external wind power generator through the power transmission line, and a control end of the inverter is connected with the feedback control module.

[0017] Additional aspects and advantages of the present application will be made apparent from the following description of embodiments of the present application, which will be described in the following description of embodiments of the present application, which will be described in the following description of embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description of embodiments of the present application, taken in conjunction with the accompanying drawings in which:

[0019] Figure 1 A structural schematic diagram of one of embodiments of the present application;

[0020] Figure 2 A schematic diagram of a feedback control module of one of embodiments of the present application. DETAILED DESCRIPTION

[0021] Embodiments of the present application are described below in detail, examples of which are shown in the accompanying drawings, in which the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below are exemplary and are intended to explain the present application, and should not be understood as limiting the present application.

[0022] In the description of the present application, it should be understood that, in relation to the orientation description, for example, the orientation or position relationship indicated by the upper, lower, front, rear, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0023] In the description of the present application, if there is a description of first, second, etc. for the purpose of distinguishing technical features, it cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0024] In the description of the present application, the words such as arrangement, installation, connection and the like should be understood broadly unless otherwise explicitly limited, and the skilled in the art can determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0025] As shown in Figure 1 The wind farm starting auxiliary power supply system according to the embodiment of the present application comprises: an auxiliary power supply module 100, which is connectable with an external wind turbine, and is used to generate alternating current for assisting the starting of the external wind turbine; and a feedback control module 200, an input end of which is connected with an output end of the auxiliary power supply module 100, and an output end of which is connected with a control end of the auxiliary power supply module 100, and which is used to adjust the size of the output voltage and / or current of the auxiliary power supply module 100.

[0026] The auxiliary power supply module 100 generates alternating current suitable for the starting of the wind turbine and transmits the alternating current to the wind turbine, so as to provide alternating current support for assisting the starting of the wind turbine. After the starting of the wind turbine is completed and the wind turbine starts to generate electricity, the alternating voltage between the auxiliary power supply module 100 and the wind turbine will increase, and the feedback control module 200 detects and controls the auxiliary power supply module 100 according to the alternating voltage, so as to make the auxiliary power supply module 100 adjust the output power to reduce the size of the output current. When the starting of the wind turbine is completed, the feedback control module 200 controls the auxiliary power supply module 100 to reduce the output current to zero, that is, the auxiliary power supply module 100 enters a standby state, which is beneficial to reducing the loss of the auxiliary power supply module 100 and the overall system.

[0027] The auxiliary power supply module 100 can be connected with a plurality of wind turbines, that is, connected with a wind farm, so as to assist the starting of the plurality of wind turbines.

[0028] Referring to Figure 2 In some embodiments of the present application, the feedback control module 200 comprises a detection unit 210 and a vector control unit 220, the detection unit 210 is connected with the output end of the auxiliary power supply module 100, the input end of the vector control unit 220 is connected with the detection unit 210, and the output end of the vector control unit 220 is connected with the auxiliary power supply module 100.

[0029] The detection unit 210 detects the alternating current between the auxiliary power supply module 100 and the wind driven generator, and feeds back the voltage and current of the alternating current to the vector control unit 220. The vector control unit 220 controls the output voltage and / or current of the auxiliary power supply module 100 according to the voltage and current of the alternating current by vector control. The voltage and current of the alternating current are processed by the vector control unit 220 by vector control, which realizes the decoupling of the flux and torque during the starting process, i.e. the control of the flux and torque respectively, which is beneficial to the vector control unit 220 to control the auxiliary power supply module 100 to output alternating current more suitable for the starting of the wind driven generator.

[0030] The detection unit 210 can be a device capable of detecting voltage and current, such as a voltage transformer and a current transformer. The number of voltage transformers and current transformers can be multiple to detect the voltage and current of each phase of the alternating current. The detection unit 210 can also be an embodiment including a common voltage effective value detection circuit to detect the voltage effective value of the alternating current.

[0031] Reference Figure 2 In some embodiments of the present application, the vector control unit 220 includes a coordinate transformation unit 221, a comparison operation unit 230 and an inverse coordinate transformation unit 222. The input end of the coordinate transformation unit 221 is connected with the detection unit 210, which is used to calculate the voltage and / or current in the DQ coordinate system according to the voltage and / or current of the alternating current. The output end of the coordinate transformation unit 221 is connected with the input end of the comparison operation unit 230, which is used to compare the voltage and / or current in the DQ coordinate system with the preset reference value to calculate the control quantity. The output end of the comparison operation unit 230 is connected with the input end of the inverse coordinate transformation unit 222, which is used to calculate the voltage control component and / or current control component according to the control quantity. The output end of the inverse coordinate transformation unit 222 is connected with the auxiliary power supply module 100, so that the auxiliary power supply module 100 adjusts the output voltage and / or current according to the voltage control component and / or current control component.

[0032] The detection unit 210 detects the voltage value and the current value of the alternating current and feeds back to the coordinate conversion unit 221 for coordinate conversion, so that the voltage value and the current value of the alternating current are converted into the voltage value and the current value in the DQ coordinate system. The comparison operation unit 230 compares the voltage value in the DQ coordinate system with the preset reference voltage value, or compares the current value in the DQ coordinate system with the preset reference current value, to obtain a control quantity according to the comparison result, which generally includes a D-axis control quantity and a Q-axis control quantity. The inverse coordinate conversion unit 222 performs inverse coordinate conversion processing on the control quantity, so that the control quantity is converted into a voltage control component for controlling the alternating voltage, or is converted into a current control component for controlling the alternating current. The auxiliary power supply module 100 adjusts the voltage value and the current value of the alternating current output according to the voltage control component and the current control component.

[0033] The coordinate conversion unit 221 adopts the Park transformation mode, and the inverse coordinate conversion unit 222 adopts the corresponding inverse Park transformation mode. The voltage value and the current value of the alternating current output by the auxiliary power supply module are converted into the voltage value and the current value in the DQ coordinate system through the Park transformation, and in the DQ coordinate system, the voltage component and the current component on the D-axis and the voltage component and the current component on the Q-axis can correspond to the control of torque and flux respectively, which is beneficial to control the auxiliary power supply module 100 to output the alternating current more suitable for the start of the auxiliary wind driven generator.

[0034] The coordinate conversion unit 221 and the inverse coordinate conversion unit 222 can be a processing program in a single-chip microcomputer, FPGA or other device capable of calculating and processing input signals.

[0035] Reference Figure 2 In some embodiments of the present application, the comparison operation unit 230 includes a D-axis voltage PI controller 231 and a Q-axis voltage PI controller 232, and the coordinate conversion unit 221 is provided with a D-axis voltage output end and a Q-axis voltage output end; a first input end of the D-axis voltage PI controller 231 is connected with the detection unit 210 or the D-axis voltage output end, a second input end of the D-axis voltage PI controller 231 receives a first preset reference voltage value, and an output end of the D-axis voltage PI controller 231 is connected with the inverse coordinate conversion unit 222; a first input end of the Q-axis voltage PI controller 232 is connected with the detection unit 210 or the Q-axis voltage output end, a second input end of the Q-axis voltage PI controller 232 receives a second preset reference voltage value, and an output end of the Q-axis voltage PI controller 232 is connected with the inverse coordinate conversion unit 222.

[0036] The coordinate conversion unit 221 is provided with a D-axis voltage output end, a D-axis current output end, a Q-axis voltage output end and a Q-axis current output end, and the coordinate conversion unit 221 converts the alternating current of the wind driven generator into the voltage value and the current value in the DQ coordinate system, which generally includes a D-axis voltage value V ac_d, the D-axis current value i d , the Q-axis voltage value V ac_q , the Q-axis current value i q , respectively corresponding to the D-axis voltage output end, the D-axis current output end, the Q-axis voltage output end and the Q-axis current output end.

[0037] The D-axis voltage PI controller 231 compares the detected voltage value of the detection unit 210 with the first preset reference voltage value V * ac_d , for example, the effective value V ac_rms of the voltage detected by the detection unit 210 is compared with V * ac_d , or the D-axis voltage value V ac_d is compared with the first preset reference voltage value V * ac_d According to the difference of the comparison, PI processing is then performed, and the calculation result is transmitted to the inverse coordinate conversion unit 222 as the D-axis control quantity, so as to control the auxiliary power supply module 100. Similarly, the Q-axis voltage PI controller 232 compares the detected voltage value of the detection unit 210 with the second preset reference voltage value V * ac_q , or the Q-axis voltage value V ac_q is compared with the second preset reference voltage value V * ac_q According to the difference of the comparison, PI processing is then performed, and the calculation result is transmitted to the inverse coordinate conversion unit 222 as the Q-axis control quantity, so as to control the auxiliary power supply module 100. In this structure, the function of voltage closed-loop control is realized in the control system, so that the voltage value of the auxiliary power supply module 100 changes with the voltage value of the alternating current between the auxiliary power supply module 100 and the wind turbine.

[0038] Referring to Figure 2 , in some embodiments of the present application, the comparison operation unit 230 further comprises a D-axis current PI controller 233 and a Q-axis current PI controller 234, and the coordinate conversion unit 221 is provided with a D-axis current output end and a Q-axis current output end; the first input end of the D-axis current PI controller 233 is connected with the output end of the D-axis voltage PI controller 231, the second input end of the D-axis current PI controller 233 is connected with the D-axis current output end, and the output end of the D-axis current PI controller 233 is connected with the inverse coordinate conversion unit 222; the first input end of the Q-axis current PI controller 234 is connected with the output end of the Q-axis voltage PI controller 232, the second input end of the Q-axis current PI controller 234 is connected with the Q-axis current output end, and the output end of the Q-axis current PI controller 234 is connected with the inverse coordinate conversion unit 222.

[0039] The D-axis current PI controller 233 uses the calculated value output by the D-axis voltage PI controller 231 as the D-axis reference current value i * d and D-axis current value i d The difference between the two is compared and PI processing is performed, and the calculated result is transmitted to the inverse coordinate transformation unit 222 as the D-axis control quantity, thereby controlling the auxiliary power supply module 100. Similarly, the Q-axis current PI controller 234 uses the calculated value output by the Q-axis voltage PI controller 232 as the Q-axis reference current value i * q and Q-axis current value i q The difference between the two is then subjected to PI processing, and the resulting calculation result is transmitted to the inverse coordinate transformation unit 222 as the Q-axis control quantity, thereby controlling the auxiliary power supply module 100. This structure implements current closed-loop control from a control system perspective, with the voltage closed-loop serving as the outer control loop and the current closed-loop serving as the inner control loop. This improves response speed and enables more rapid adjustment of the output power of the auxiliary power supply module 100 based on the voltage and current values ​​of the AC power.

[0040] The D-axis voltage PI controller 231, the D-axis current PI controller 233, the Q-axis voltage PI controller 232 and the Q-axis current PI controller 234 can be implemented by hardware, that is, including common comparison circuits, proportional circuits and integration circuit implementation methods; they can also be implemented by software, that is, devices such as microcontrollers and FPGAs that can perform calculations and processing, and compare, proportional and integrate the received signal values ​​through software programs to achieve the processing of analog PI controllers, thereby obtaining the calculation results.

[0041] Reference Figure 2 In some embodiments of the present invention, the comparison operation unit 230 further includes a D-axis limiting unit 235 and a Q-axis limiting unit 236; the output end of the D-axis voltage PI controller 231 is connected to the input end of the D-axis limiting unit 235, and the output end of the D-axis limiting unit 235 is connected to the first input end of the D-axis current PI controller 233. The D-axis limiting unit 235 is used to limit the output value of the D-axis voltage PI controller 231 within a preset range; the output end of the Q-axis voltage PI controller 232 is connected to the input end of the Q-axis limiting unit 236, and the output end of the Q-axis limiting unit 236 is connected to the first input end of the Q-axis current PI controller 234. The Q-axis limiting unit 236 is used to limit the output value of the Q-axis voltage PI controller 232 within a preset range.

[0042] The output power of the auxiliary power supply module 100 needs to be within a proper range. By providing the D-axis limiting unit 235, the output value of the D-axis voltage PI controller 231 is limited within a preset range, and by providing the Q-axis limiting unit 236, the output value of the Q-axis voltage PI controller 232 is limited within a preset range, so that the subsequent D-axis control quantity and Q-axis control quantity transmitted to the inverse coordinate conversion unit 222 are also limited within a certain range, and thus the power output by the auxiliary power supply module 100 is limited within a certain range.

[0043] By providing the D-axis limiting unit 235, the auxiliary power supply module 100 can only provide active power to the wind farm, and the situation of power being sent back is limited. Preferably, the limiting range of the D-axis limiting unit 235 is 0 to 1 p.u., and the limiting range of the Q-axis limiting unit 236 is -1 p.u. to +1 p.u., and 1 p.u. (per unit) is equal to the rated voltage value of the wind turbine.

[0044] Reference Figure 2 In some embodiments of the present application, the comparison operation unit 230 further comprises a linkage unit 237, the input end of the linkage unit 237 is connected with the output end of the Q-axis voltage PI controller 232, the output end of the linkage unit 237 is connected with the first input end of the Q-axis current PI controller 234, and the control end of the linkage unit 237 is connected with the output end of the D-axis PI voltage controller. The linkage unit 237 is used for limiting the output value range of the Q-axis voltage PI controller 232 according to the output value of the D-axis PI voltage controller.

[0045] After the wind turbine starts to generate power, the output values of the D-axis PI controller and the Q-axis PI controller gradually decrease. When the wind turbine completes the start to output power, the output values of the D-axis PI controller and the Q-axis PI controller decrease to zero, so that the output current of the auxiliary power supply module 100 decreases to zero and enters the standby state.

[0046] In order to limit the output of the Q-axis voltage PI controller 232 to zero when the output of the D-axis voltage PI controller 231 is zero, so as to avoid the problem of system oscillation during the switching state of the auxiliary power supply module 100. For this purpose, by providing the linkage unit 237, the linkage unit 237 limits the output value range of the Q-axis voltage PI controller 232 according to the output value of the D-axis voltage PI controller 231, so that when the output of the D-axis voltage PI controller 231 is zero, the output of the Q-axis voltage PI controller 232 is also limited to zero.

[0047] The linkage unit 237 can multiply the output value of the D-axis voltage PI controller 231 by a preset coefficient as a limiting value, and the absolute values of the positive limiting value and the negative limiting value are the same.

[0048] Referring to Figure 1 In some embodiments of the present application, the auxiliary power supply module 100 includes a power transmission line 120 and a power electronic device 110 or a load-regulated voltage transformer, the input end of the power electronic device 110 is connected with an external power grid or an external direct-current power transmission system, the input end of the load-regulated voltage transformer is connected with the external power grid, the output end of the power electronic device 110 or the output end of the load-regulated voltage transformer is connected with an external wind turbine through the power transmission line 120, and the control end of the power electronic device 110 or the control end of the load-regulated voltage transformer is connected with the feedback control module 200.

[0049] The power electronic device 110 obtains electric energy from the power grid or the direct-current power transmission system, converts the electric energy to form appropriate alternating current for assisting the start of the wind turbine, and then transmits the alternating current to the wind turbine through the power transmission line 120 to assist the start of the wind turbine. The power electronic device 110 obtains electric energy from the power grid or the direct-current power transmission system, which is more stable and reliable. The load-regulated voltage transformer obtains alternating current from the power grid, processes the alternating current, and then transmits the processed alternating current to the wind turbine through the power transmission line 120. The load-regulated voltage transformer has a simple structure and is easy to use. The power transmission line 120 can be an alternating current submarine cable, an overhead line, or a cable, etc.

[0050] In some embodiments of the present application, the power electronic device 110 includes a back-to-back converter, the input end of the back-to-back converter is connected with the external power grid, the output end of the back-to-back converter is connected with the external wind turbine through the power transmission line 120, and the control end of the back-to-back converter is connected with the feedback control module 200.

[0051] The back-to-back converter includes a rectifier side and an inverter side, the input end of the back-to-back converter, i.e., the rectifier side, is connected with the power grid to rectify the alternating current of the power grid into direct current and transmit the direct current to the inverter side, and the inverter side inversely converts the direct current into appropriate alternating current for assisting the start of the wind turbine under the control of the feedback control module 200 and transmits the alternating current to the wind turbine.

[0052] The back-to-back converter has a specific topology structure, in a small power scenario, can include a common three-phase bridge rectifier circuit and a three-phase bridge inverter circuit, the three-phase bridge rectifier circuit as the rectifier side is connected with the power grid, the three-phase bridge rectifier circuit outputs direct current to the three-phase bridge inverter circuit, and the three-phase bridge inverter circuit as the inverter side is connected with the wind turbine; in a large power scenario, can include a structure of two groups of three-phase MMC (Modular Multilevel) symmetrically arranged.

[0053] In some embodiments of the present application, the power electronic device 110 includes an inverter, the input end of the inverter is connected with an external direct-current power transmission system, the output end of the inverter is connected with an external wind turbine through the power transmission line 120, and the control end of the inverter is connected with the feedback control module 200.

[0054] Offshore wind farms are connected to the grid by DC transmission technology, that is, the AC power output by the wind turbine in the offshore wind farm is converted into DC power by rectifier equipment, and then the DC power is transmitted to the inverter equipment on the land by DC submarine cable, and the inverter equipment converts the DC power into AC power suitable for being connected to the grid. Therefore, the inverter is connected to the DC transmission system to obtain DC power, and the inverter converts the DC power into AC power suitable for assisting the start of the wind turbine under the control of the feedback control module 200 and transmits the AC power to the wind turbine.

[0055] The specific topology of the inverter can be a three-phase bridge inverter circuit in a small power application, and can be a three-phase MMC structure in a large power application.

[0056] Of course, the present application is not limited to the above-mentioned embodiments, and those skilled in the art can make equivalent modifications or replacements without departing from the spirit of the present application, and these equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. A wind farm start-up auxiliary power supply system, characterized by, The utility model relates to an auxiliary power supply module (100) can be connected with external wind driven generator, the auxiliary power supply module (100) is used to generate auxiliary external wind driven generator starting AC power supply; Feedback control module (200) input with the output of auxiliary power supply module (100) is connected, and the output of feedback control module (200) is connected with the control end of auxiliary power supply module (100), and feedback control module (200) is used to adjust the size of output voltage and / or current of auxiliary power supply module (100); The feedback control module (200) includes detection unit (210) and vector control unit (220), and the detection unit (210) is connected with the output of auxiliary power supply module (100), and the input of vector control unit (220) is connected with detection unit (210), and the output of vector control unit (220) is connected with auxiliary power supply module (100); The vector control unit (220) includes coordinate transformation unit (221), comparison operation unit (230) and inverse coordinate transformation unit (222), and the input of coordinate transformation unit (221) is connected with detection unit (210), and coordinate transformation unit (221) is used to calculate the voltage value and / or current value under DQ coordinate system according to the voltage value and / or current value of AC power supply, and the output of coordinate transformation unit (221) is connected with the input of comparison operation unit (230), and comparison operation unit (230) is used to compare the voltage value and / or current value under DQ coordinate system with preset reference value to calculate control quantity, and the output of comparison operation unit (230) is connected with the input of inverse coordinate transformation unit (222), and inverse coordinate transformation unit (222) is used to calculate voltage control component and / or current control component according to control quantity, and the output of inverse coordinate transformation unit (222) is connected with auxiliary power supply module (100), so that auxiliary power supply module (100) adjusts the size of output voltage and / or current according to voltage control component and / or current control component; The comparison operation unit (230) includes D-axis voltage PI controller (231) and Q-axis voltage PI controller (232), and coordinate transformation unit (221) is provided with D-axis voltage output and Q-axis voltage output; The first input of D-axis voltage PI controller (231) is connected with detection unit (210) or D-axis voltage output, the second input of D-axis voltage PI controller (231) receives first preset reference voltage value, and the output of D-axis voltage PI controller (231) is connected with inverse coordinate transformation unit (222); ​ A first input end of the Q-axis voltage PI controller (232) is connected with the detection unit (210) or the Q-axis voltage output end, a second input end of the Q-axis voltage PI controller (232) receives a second preset reference voltage value, and an output end of the Q-axis voltage PI controller (232) is connected with the inverse coordinate transformation unit (222); The comparison operation unit (230) further comprises a D-axis current PI controller (233) and a Q-axis current PI controller (234), and the coordinate transformation unit (221) is provided with a D-axis current output end and a Q-axis current output end; A first input end of the D-axis current PI controller (233) is connected with an output end of the D-axis voltage PI controller (231), a second input end of the D-axis current PI controller (233) is connected with the D-axis current output end, and an output end of the D-axis current PI controller (233) is connected with the inverse coordinate transformation unit (222); a first input end of the Q-axis current PI controller (234) is connected with an output end of the Q-axis voltage PI controller (232), a second input end of the Q-axis current PI controller (234) is connected with the Q-axis current output end, and an output end of the Q-axis current PI controller (234) is connected with the inverse coordinate transformation unit (222); and the comparison operation unit (230) further comprises a D-axis limiting unit (235) and a Q-axis limiting unit (236); An output end of the D-axis voltage PI controller (231) is connected with an input end of the D-axis limiting unit (235), an output end of the D-axis limiting unit (235) is connected with a first input end of the D-axis current PI controller (233), and the D-axis limiting unit (235) is used for limiting an output value of the D-axis voltage PI controller (231) in a preset range; An output end of the Q-axis voltage PI controller (232) is connected with an input end of the Q-axis limiting unit (236), an output end of the Q-axis limiting unit (236) is connected with a first input end of the Q-axis current PI controller (234), and the Q-axis limiting unit (236) is used for limiting an output value of the Q-axis voltage PI controller (232) in a preset range; The comparison operation unit (230) further comprises a linkage unit (237), an input end of the linkage unit (237) is connected with an output end of the Q-axis voltage PI controller (232), an output end of the linkage unit (237) is connected with a first input end of the Q-axis current PI controller (234), a control end of the linkage unit (237) is connected with an output end of the D-axis voltage PI controller (231), the linkage unit (237) is used for limiting an output value range of the Q-axis voltage PI controller (232) according to an output value of the D-axis voltage PI controller (231), wherein when the D-axis voltage PI controller (231) outputs zero, the linkage unit (237) limits the Q-axis voltage PI controller (232) to output zero, so as to avoid system oscillation in the switching state process of the auxiliary power supply module (100).

2. The wind farm start-up auxiliary power supply system of claim 1, wherein: The auxiliary power supply module (100) comprises a power transmission line (120) and a power electronic device (110) or a load-regulated voltage transformer, an input end of the power electronic device (110) is connected with an external power grid or an external direct-current power transmission system, an input end of the load-regulated voltage transformer is connected with the external power grid, an output end of the power electronic device (110) or an output end of the load-regulated voltage transformer is connected with an external wind turbine through the power transmission line (120), and a control end of the power electronic device (110) or a control end of the load-regulated voltage transformer is connected with the feedback control module (200).

3. The wind farm start-up auxiliary power supply system of claim 2, wherein: The power electronic device (110) comprises a back-to-back converter, an input end of the back-to-back converter is connected with the external power grid, an output end of the back-to-back converter is connected with the external wind turbine through the power transmission line (120), and a control end of the back-to-back converter is connected with the feedback control module (200).

4. The wind farm start-up auxiliary power supply system of claim 2, wherein: The power electronic device (110) comprises an inverter, an input end of the inverter is connected with the external direct-current power transmission system, an output end of the inverter is connected with the external wind turbine through the power transmission line (120), and a control end of the inverter is connected with the feedback control module (200).

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