Yaw control system of wind generating set and wind generating set

Abstract

The invention provides a yaw control system of a wind generating set and the wind generating set, and aims to solve the problems that the cost pressure of a yaw system is increased and the economical efficiency of yaw is poor during light-load operation. In the system, a yaw protection circuit breaker is connected to the secondary side of a distribution transformer; the first contactor is connected between the yaw protection circuit breaker and a stator of the yaw motor; the second contactor is connected in parallel with two ends of the stator of each yaw motor; the third contactor is connected between the yaw protection circuit breaker and the input end of the yaw frequency converter; the fourth contactor is connected between the output end of the yaw frequency converter and the rotor of each yaw motor; the fifth contactor is connected to the two ends of the rotor of each yaw motor in parallel; the system is configured to realize automatic switching between a doubly-fed variable-speed operation mode and an asynchronous constant-speed operation mode by controlling on-off of the first contactor to the fifth contactor and starting and stopping of the yaw frequency converter.

Description

Technical Field

[0001] This application relates to the field of wind power generation, specifically to a yaw control system for a wind turbine generator set and a wind turbine generator set. Background Art

[0002] With the increasing size of wind turbine generators, yaw loads are becoming larger and larger, and the required yaw drive power is also increasing. However, in actual operation, the yaw drive power fluctuates within a large range. Currently, the yaw drive is designed to be compatible with the maximum power requirement, which increases the cost pressure of the yaw system and makes the yaw less economical when operating under light load. Summary of the Invention

[0003] To address the issues of increased cost pressures and poor economic efficiency of yaw systems under light loads, this application provides a yaw control system for a wind turbine generator set and a wind turbine generator set.

[0004] The technical solution of this invention is as follows: This invention provides a yaw control system for a wind turbine generator set, comprising: Distribution transformer (T1), yaw protection circuit breaker (F1), multiple yaw motors (M3), yaw frequency converter (U1), and first contactor (Q1) to fifth contactor (Q5); The yaw protection circuit breaker (F1) is connected to the secondary side of the distribution transformer (T1); The first contactor (Q1) is connected between the yaw protection circuit breaker (F1) and the stator of the yaw motor (M3); The second contactor (Q2) is connected in parallel to the stator terminals of each yaw motor (M3); The third contactor (Q3) is connected between the yaw protection circuit breaker (F1) and the input terminal of the yaw frequency converter (U1); The fourth contactor (Q4) is connected between the output terminal of the yaw inverter (U1) and the rotor of each yaw motor (M3); The fifth contactor (Q5) is connected in parallel to both ends of the rotor of each yaw motor (M3); The system is configured to automatically switch between doubly fed variable speed operation mode and asynchronous constant speed operation mode by controlling the on / off state of the first contactor (Q1) to the fifth contactor (Q5) and the start / stop state of the yaw inverter (U1).

[0005] Preferably, when the yaw inverter is operating normally, the doubly fed variable speed mode is executed; In the event of a yaw inverter failure, an asynchronous constant speed operation mode is executed; Automatic switching between two operating modes is achieved by controlling the opening and closing states of the first contactor (Q1) to the fifth contactor (Q5) and the operating state of the yaw inverter (U1).

[0006] Preferably, the rated capacity of the yaw inverter (U1) is configured to be 25% to 30% of the total rated power of all the yaw motors (M3).

[0007] Preferably, the doubly-fed variable speed operation mode includes an asynchronous start-up phase and a synchronous grid connection phase executed sequentially: During the asynchronous start-up phase, the first contactor (Q1) and the fifth contactor (Q5) are disconnected, the second contactor (Q2) is closed to short-circuit the stator winding of the yaw motor (M3), and the third contactor (Q3) and the fourth contactor (Q4) are closed to activate the soft start function of the yaw inverter (U1), so that the yaw motor (M3) starts asynchronously. During the synchronous grid connection phase, when the speed of each yaw motor (M3) reaches the preset synchronous speed threshold N, the second contactor (Q2) is disconnected, and the yaw frequency converter (U1) applies excitation to the rotor of each yaw motor (M3) to synchronize the stator voltage with the grid. Then, the first contactor (Q1) is closed, thereby connecting the stator of each yaw motor (M3) to the grid and entering doubly fed variable speed operation.

[0008] Preferably, after the grid connection phase, the system enters a stable operating state; The yaw inverter (U1) monitors the output active power of all yaw motors (M3) in real time; When the output active power is lower than a preset percentage X% of the rated power, the yaw inverter (U1) injects capacitive reactive power into the grid with constant apparent power as the control target to improve the grid power factor.

[0009] Preferably, during the shutdown phase of the doubly fed variable speed operation mode, the yaw inverter (U1) controls the deceleration of each yaw motor (M3); When the rotational speed drops to the preset shutdown threshold N1, the first contactor (Q1) is disconnected.

[0010] Preferably, in the event of a yaw inverter failure, the second contactor (Q2), the third contactor (Q3), and the fourth contactor (Q4) are disconnected to isolate the yaw inverter (U1) from the main circuit. Close the fifth contactor (Q5) to short-circuit the rotor winding of the yaw motor (M3); Close the first contactor (Q1) to make the yaw motor (M3) run at a constant speed in asynchronous motor mode.

[0011] This application also provides a wind turbine generator set, which includes the yaw control system of the wind turbine generator set as described above.

[0012] The beneficial effects of this invention are as follows: This system, through the coordinated control of the yaw inverter and the first to fifth contactors, forms a flexible switching path in the stator and rotor circuits of the doubly fed motor. This allows the yaw motor to achieve wide-range smooth speed regulation under inverter control in a doubly fed mode, and to switch to asynchronous motor constant speed operation by shorting the contactor when the inverter fails. In principle, this realizes the automatic redundant switching between the two modes of efficient speed regulation and reliable constant speed of the yaw system, improving the system's adaptability and reliability to different operating conditions and fault states. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the yaw control system of the wind turbine generator set in the embodiments of this application. Detailed Implementation

[0014] Doubly fed induction generators (DFIGs) can operate around synchronous speeds, meaning they can operate in subsynchronous and supersynchronous conditions. Their speed range is wider than that of ordinary asynchronous motors, resulting in better dynamic performance and bidirectional energy flow. By adjusting the rotor excitation, the operating conditions of the DFIG can be controlled. On one hand, it allows the DFIG to fluctuate around synchronous speeds (i.e., subsynchronous and supersynchronous operation), expanding the yaw motor's operating speed range. On the other hand, under light load conditions, it maintains constant apparent power. When the load fluctuates, i.e., when the motor's active power output fluctuates, the DFIG can control its capacitive reactive power output to compensate for reactive power in the distribution network, thereby improving the power factor of the distribution transformer's power supply circuit and reducing losses. Furthermore, the inverter capacity matched to the DFIG is significantly reduced compared to traditional full-power inverters, typically about 25%, resulting in a significant cost reduction. Additionally, an isolation contactor is added to the DFIG inverter, allowing conventional asynchronous motor operation in the event of a DFIG inverter failure, improving the reliability of the unit's yaw system.

[0015] This invention provides a yaw control system for a wind turbine generator set, the circuit structure of which is as follows: Figure 1 As shown. The system mainly includes a distribution transformer T1, a yaw protection circuit breaker F1, multiple yaw motors M3, a yaw frequency converter U1, and first contactors Q1 (i.e., yaw motor stator contactors) to fifth contactors Q5 (i.e., yaw motor rotor short-circuit contactors).

[0016] The yaw protection circuit breaker F1 is connected to the secondary side of the distribution transformer T1 to provide power and protection for the entire yaw system. The first contactor Q1 is connected between the yaw protection circuit breaker F1 and the stator of the yaw motor M3, controlling the connection and disconnection of the stator circuit to the power grid. The second contactor Q2 (i.e., the yaw motor stator short-circuit contactor) is connected in parallel across the stator terminals of each yaw motor M3 to short-circuit the stator windings, enabling asynchronous starting. The third contactor Q3 (i.e., the inverter input contactor) is connected between the yaw protection circuit breaker F1 and the input terminal of the yaw inverter U1, controlling the power input to the inverter. The fourth contactor Q4 (i.e., the inverter output contactor) is connected between the output terminal of the yaw inverter U1 and the rotor of each yaw motor M3, connecting the inverter to the rotor circuit. The fifth contactor Q5 is connected in parallel across the rotor terminals of each yaw motor M3 to short-circuit the rotor windings, enabling asynchronous operation.

[0017] By coordinating the on / off of the first contactor Q1 to the fifth contactor Q5 and the start / stop of the yaw inverter U1, the system can automatically switch between doubly fed variable speed operation mode and asynchronous constant speed operation mode, which significantly improves the reliability and operating efficiency of the system.

[0018] In this embodiment of the application, the construction and operation of the yaw control system of the wind turbine generator set includes the following steps: The first step is to select the number n of yaw motors M3 based on the yaw load of the unit. The capacity of the distribution transformer T1 is determined according to the needs of the entire power distribution circuit. The yaw protection circuit breaker F1, the first contactor Q1, the second contactor Q2, and the fifth contactor Q5 are all selected based on the number of yaw motors and their operating current; the third contactor Q3 and the fourth contactor Q4 are selected based on the operating current of the yaw inverter U1.

[0019] The second step involves selecting a doubly-fed inverter, specifically the yaw inverter U1, with a design capacity of 25% to 30% of the total rated power of all yaw motors. This capacity is sufficient to handle the motor's slip power, ensuring that the inverter can efficiently control the motor's operation.

[0020] The third step, during yaw start-up, involves first disconnecting the first contactor Q1 and the fifth contactor Q5; then closing the second contactor Q2 to short-circuit the stator windings of the yaw motor M3; next, closing the third contactor Q3 and the fourth contactor Q4; finally, starting the yaw inverter U1, which uses its soft-start function to control the yaw motor M3 for asynchronous start-up. This starting method effectively reduces the starting current surge and minimizes the impact on the power grid.

[0021] The fourth step involves the yaw motor M3 reaching its preset speed N, which triggers the synchronization control phase. The second contactor Q2 is disconnected, allowing the yaw inverter U1 to excite the motor rotor and precisely adjust the stator voltage amplitude, frequency, and phase to synchronize with the power grid. Subsequently, the first contactor Q1 is closed, smoothly connecting the stator of the yaw motor M3 to the power grid, achieving doubly-fed variable-speed operation. This synchronization process avoids current surges and ensures the stability of grid-connected operation.

[0022] Fifth, during doubly-fed variable speed operation, the yaw inverter U1 monitors the output active power of the yaw motor M3 in real time. When this output active power is lower than X% of the rated power, the system automatically aims to maintain a constant apparent power. By adjusting the capacitive reactive power injected into the grid, the grid power factor can be improved, effectively reducing system losses. When the yaw load changes significantly, the yaw motor can operate in subsynchronous or supersynchronous states, with the rotor absorbing power from and feeding power into the distribution network, allowing the motor speed to be continuously adjusted within the range above and below the synchronous speed. This significantly expands the motor's operating speed range and improves the dynamic response performance of the yaw system.

[0023] The sixth step involves the yaw inverter U1 controlling the motor to smoothly decelerate when the unit's yaw ends. Once the speed drops to the preset value N1, the first contactor Q1 is disconnected, completing the shutdown process. This shutdown method avoids mechanical shock and extends the equipment's service life.

[0024] Step 7: If the yaw inverter U1 fails, the system automatically switches to asynchronous constant speed operation mode: disconnecting the second contactor Q2, the third contactor Q3, and the fourth contactor Q4 completely isolates the faulty inverter from the main circuit; closing the fifth contactor Q5 short-circuits the rotor winding; and then closing the first contactor Q1, causing the yaw motor M3 to operate as an asynchronous motor. This redundancy design ensures that the basic yaw function of the unit can still be maintained in the event of an inverter failure, greatly improving the reliability and availability of the system.

[0025] Currently, wind turbine yaw electrical drives often employ a one-to-many inverter approach, where one yaw inverter drives multiple yaw motors. As the power of the yaw motors increases in tandem with the overall turbine power, the required power and cost of the yaw inverter also increase. The yaw control system design described in this invention reduces the power rating of the yaw inverter while simultaneously improving the yaw system's drive capability and lowering its cost.

[0026] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0027] Furthermore, the functional units in the various embodiments of this disclosure can be integrated into a single processing module, or each unit can exist physically separately, or two or more units can be integrated into a single module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. The aforementioned storage medium can be a read-only memory, a hard disk, or an optical disk, etc.

[0028] Although embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A yaw control system for a wind turbine generator set, characterized in that, include: Distribution transformer (T1), yaw protection circuit breaker (F1), multiple yaw motors (M3), yaw frequency converter (U1), and first contactor (Q1) to fifth contactor (Q5); The yaw protection circuit breaker (F1) is connected to the secondary side of the distribution transformer (T1); The first contactor (Q1) is connected between the yaw protection circuit breaker (F1) and the stator of the yaw motor (M3); The second contactor (Q2) is connected in parallel to the stator terminals of each yaw motor (M3); The third contactor (Q3) is connected between the yaw protection circuit breaker (F1) and the input terminal of the yaw frequency converter (U1); The fourth contactor (Q4) is connected between the output terminal of the yaw inverter (U1) and the rotor of each yaw motor (M3); The fifth contactor (Q5) is connected in parallel to both ends of the rotor of each yaw motor (M3); The system is configured to automatically switch between doubly fed variable speed operation mode and asynchronous constant speed operation mode by controlling the on / off state of the first contactor (Q1) to the fifth contactor (Q5) and the start / stop state of the yaw inverter (U1).

2. The yaw control system of the wind turbine generator set according to claim 1, characterized in that, When the yaw inverter is functioning normally, the doubly fed variable speed operation mode is executed. In the event of a yaw inverter failure, an asynchronous constant speed operation mode is executed; Automatic switching between two operating modes is achieved by controlling the opening and closing states of the first contactor (Q1) to the fifth contactor (Q5) and the operating state of the yaw inverter (U1).

3. The yaw control system for a wind turbine generator set according to claim 1 or 2, characterized in that, The rated capacity of the yaw inverter (U1) is configured to be 25% to 30% of the total rated power of all the yaw motors (M3).

4. The yaw control system of the wind turbine generator set according to claim 1 or the present invention, characterized in that, The doubly-fed variable speed operation mode includes an asynchronous start-up phase and a synchronous grid connection phase executed sequentially: During the asynchronous start-up phase, the first contactor (Q1) and the fifth contactor (Q5) are disconnected, the second contactor (Q2) is closed to short-circuit the stator winding of the yaw motor (M3), and the third contactor (Q3) and the fourth contactor (Q4) are closed to activate the soft start function of the yaw inverter (U1), so that the yaw motor (M3) starts asynchronously. During the synchronous grid connection phase, when the speed of each yaw motor (M3) reaches the preset synchronous speed threshold N, the second contactor (Q2) is disconnected, and the yaw frequency converter (U1) applies excitation to the rotor of each yaw motor (M3) to synchronize the stator voltage with the grid. Then, the first contactor (Q1) is closed, thereby connecting the stator of each yaw motor (M3) to the grid and entering doubly fed variable speed operation.

5. The yaw control system of the wind turbine generator set according to claim 4, characterized in that, After the synchronization and grid connection phase, the system enters a stable operating state; The yaw inverter (U1) monitors the output active power of all yaw motors (M3) in real time; When the output active power is lower than a preset percentage X% of the rated power, the yaw inverter (U1) injects capacitive reactive power into the grid with constant apparent power as the control target to improve the grid power factor.

6. The yaw control system of the wind turbine generator set according to claim 4, characterized in that, During the shutdown phase of the doubly fed variable speed operation mode, the yaw inverter (U1) controls the deceleration of each yaw motor (M3); When the rotational speed drops to the preset shutdown threshold N1, the first contactor (Q1) is disconnected.

7. The yaw control system of the wind turbine generator set according to claim 2, characterized in that, In the event of a yaw inverter failure, disconnect the second contactor (Q2), the third contactor (Q3), and the fourth contactor (Q4) to isolate the yaw inverter (U1) from the main circuit. Close the fifth contactor (Q5) to short-circuit the rotor winding of the yaw motor (M3); Close the first contactor (Q1) to make the yaw motor (M3) run at a constant speed in asynchronous motor mode.

8. A wind turbine generator set comprising a yaw control system for a wind turbine generator set as described in any one of claims 1-7.

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