A high-pass transformation method for a wind turbine variable pitch control system

Abstract

This invention relates to a high-voltage ride-through (HVRT) retrofit method for a wind turbine pitch control system. The method involves adding a HVRT control bit to the communication protocol of the main control system. When the main control system detects a high voltage event, it sets the HVRT control bit to "1" and sends a HVRT signal to the pitch control system, which then executes the HVRT strategy. Conversely, when a high voltage event is detected, the HVRT control bit is set to "0," and the main control system does not send a HVRT signal to the pitch control system, which then executes normal and non-HVRT strategies. This invention ensures stable operation of the pitch system within a controllable range, reduces the fault area, minimizes unnecessary resource waste, allows for rapid identification and repair of faults, prevents wind turbine grid disconnection accidents, and guarantees the normal operation of the pitch system.

Description

Technical Field

[0001] This invention relates to the field of green new energy and environmental protection technology for wind power generation systems, and in particular to a high-speed retrofit method for the pitch control system of a wind turbine generator set. Background Technology

[0002] In recent years, my country's wind power generation technology has made continuous progress, and wind turbine units have developed rapidly. However, many problems and challenges still exist in the development process. High-voltage ride-through technology for wind turbine units is one of the difficulties. With the development of my country's wind power industry, industry standards are also gradually improving. Because the withstand voltage of the charging power supply of the previous pitch system was 1.19Un (rated voltage), it did not meet the new standard for high-voltage ride-through (up to 1.3Un). The original solution was to directly replace the charging power supply, which increased the system cost.

[0003] If a grid fault occurs, the response characteristics of the relevant equipment in the wind turbines will significantly impact power generation. Therefore, appropriate high-voltage ride-through upgrades are necessary. The aim is to improve the grid connection characteristics of wind power, achieve real-time energy balance in the system, and ensure stable voltage and current. Improving the grid connection characteristics of wind power ensures balanced grid operation during short-term faults, prevents grid disconnection, and reduces the area affected by the fault.

[0004] High-voltage ride-through (HVRT) technology for wind turbines refers to ensuring that wind turbines do not disconnect from the grid and that the system maintains operational stability within a certain timeframe and voltage range when a grid fault or external disturbance causes voltage instability. To meet HVRT requirements without increasing costs and enhancing market competitiveness, the HVRT retrofit scheme for pitch control systems needs to be optimized. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the technical problem to be solved by this patent application is how to provide a high-penetration retrofit method for the pitch control system of wind turbine generator sets, which can ensure the stable operation of the pitch system within a controllable range, reduce the fault occurrence area, reduce unnecessary waste of resources, find out the cause of the fault in a short time and repair it in a timely manner, avoid wind turbine generator set grid disconnection accidents, and ensure the normal operation of the pitch system.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for retrofitting a wind turbine pitch control system involves adding a high-voltage ride-through control bit to the communication protocol of the main control system. When the main control system detects a high voltage, it sets the high-voltage ride-through control bit to "1" and sends a high-voltage ride-through signal to the pitch control system, which then executes the high-voltage ride-through strategy. Conversely, when the high-voltage ride-through control bit is set to "0", the main control system does not send a high-voltage ride-through signal to the pitch control system, which then executes normal and non-high-voltage ride-through strategies.

[0008] When executing the high-voltage ride-through strategy, if the power output can be restored within 12 seconds after the pitch control system receives the high-voltage ride-through signal command from the master control system, the pitch control system will not report a power failure; if the power output cannot be restored within 12 seconds after the pitch control system receives the high-voltage ride-through signal command from the master control system, the pitch control system will report a power failure.

[0009] If the pitch control system does not issue a high-through signal command, it will report a power failure after 6 seconds.

[0010] During high-voltage ride-through, the pitch control system makes the following adjustments:

[0011] The backup power supply low voltage fault value has been adjusted from 40V to 50V. When the backup power supply voltage is lower than 50V, the pitch system will shut down unconditionally.

[0012] During the high-altitude traverse, the main power supply delay time is 12 seconds, while in the non-high-altitude traverse, the main power supply delay time is 6 seconds. In both states, if the main power supply failure time exceeds the respective judgment time, the pitch system will shut down unconditionally.

[0013] In the simulation test, the main control system can open the blades to 70 degrees, simulate a high-speed pass signal to the pitch control system, disconnect the contactor, and then trigger an emergency stop. At this time, the safety chain is disconnected and the blades automatically feather, which proves that the emergency stop function is normal during the simulated high-speed pass and ensures the safety of subsequent tests.

[0014] The pitch control system is designed to disconnect the main power supply and be powered by a supercapacitor during high-altitude traverse. According to the high-altitude traverse requirements, the supercapacitor needs to provide power for a maximum of 12 seconds. At the same time, to ensure safety, the remaining capacity of the supercapacitor is required to ensure the safe retraction of the pitch in the event of a unit failure.

[0015] When the machine is stopped, disconnecting the contactor causes a 70-89 degree reciprocating pitch movement on one blade, which consumes capacitor voltage. When the voltage of the pitch supercapacitor drops below 50V, the system reports a low capacitor voltage fault.

[0016] In summary, this invention can ensure the stable operation of the pitch system within a controllable range, reduce the area of ​​failure, reduce unnecessary waste of resources, identify the cause of failure and repair it in a short time, avoid wind turbine disconnection accidents, and ensure the normal operation of the pitch system. Attached Figure Description

[0017] Figure 1 This is a data graph showing the data after disconnecting the main power supply 8 seconds after grid connection.

[0018] Figure 2 This is a data graph showing the data after the main power supply is disconnected for 10 seconds following grid connection.

[0019] Figure 3 This is a data graph showing the data after the main power supply is disconnected for 12 seconds following grid connection.

[0020] Figure 4 This is a test data graph simulating a 400V input fault in the pitch control system. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings. In the description of the present invention, it should be understood that directional terms such as "upper," "lower," "top," and "bottom" indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. These terms are used only for the convenience of describing the present invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of the present invention. The directional terms "inner" and "outer" refer to the inner or outer contours relative to the outline of each component itself.

[0022] A method for retrofitting a wind turbine pitch control system involves adding a high-voltage ride-through control bit to the communication protocol of the main control system. When the main control system detects a high voltage, it sets the high-voltage ride-through control bit to "1" and sends a high-voltage ride-through signal to the pitch control system, which then executes the high-voltage ride-through strategy. Conversely, when the high-voltage ride-through control bit is set to "0", the main control system does not send a high-voltage ride-through signal to the pitch control system, which then executes normal and non-high-voltage ride-through strategies.

[0023] When executing the high-voltage ride-through strategy, if the power output can be restored within 12 seconds after the pitch control system receives the high-voltage ride-through signal command from the master control system, the pitch control system will not report a power failure; if the power output cannot be restored within 12 seconds after the pitch control system receives the high-voltage ride-through signal command from the master control system, the pitch control system will report a power failure.

[0024] If the pitch control system does not issue a high-through signal command, it will report a power failure after 6 seconds.

[0025] When the machine is stopped, disconnecting the contactor causes a 70-89 degree reciprocating pitch movement on one blade, which consumes capacitor voltage. When the voltage of the pitch supercapacitor drops below 50V, the system reports a low capacitor voltage fault.

[0026] In the simulation test, the main control system can open the blades to 70 degrees, simulate a high-speed pass signal to the pitch control system, disconnect the contactor, and then trigger an emergency stop. At this time, the safety chain is disconnected and the blades automatically feather, which proves that the emergency stop function is normal during the simulated high-speed pass and ensures the safety of subsequent tests.

[0027] During high-voltage ride-through, the pitch control system makes the following adjustments:

[0028] The backup power supply low voltage fault value has been adjusted from 40V to 50V. When the backup power supply voltage is lower than 50V, the pitch system will shut down unconditionally.

[0029] During the high-altitude traverse, the main power supply delay time is 12 seconds, while in the non-high-altitude traverse, the main power supply delay time is 6 seconds. In both states, if the main power supply failure time exceeds the respective judgment time, the pitch system will shut down unconditionally.

[0030] The pitch control system is designed to disconnect the main power supply and be powered by a supercapacitor during high-altitude traverse. According to the high-altitude traverse requirements, the supercapacitor needs to provide power for a maximum of 12 seconds. At the same time, to ensure safety, the remaining capacity of the supercapacitor is required to ensure the safe retraction of the pitch in the event of a unit failure.

[0031] The specific testing plan is as follows:

[0032] When the main control system issues a high-through signal command, a high-through function test is performed. At this time, neither of the two main power supplies for the pitch control system should have any output. If the power output can be restored within 12 seconds of receiving the high-through command from the main control system, no power failure will be reported. If it cannot be restored within 12 seconds, a power failure will be reported after 12 seconds, and the blades of the three pitch control systems will execute a feathering command, causing the blades to rotate to the safe position of 89°.

[0033] If the master control system does not issue a high-penetration command, and the power supply itself malfunctions (i.e., the 400V pitch power supply fails), the rotor will lock in a Y-shape, the pitch blades will rotate to 70 degrees, and the nacelle control cabinet will disconnect the 400V pitch power supply. If the master control system does not issue a high-penetration signal at this time, the pitch system will report a power failure after 6 seconds and execute a feathering command to rotate the blades to a safe position of 89 degrees.

[0034] Test results

[0035] 1. Light wind test (wind speed ≤ 10m / s)

[0036] 1) After the generator unit is started and connected to the grid and the power is stable, start the waveform recording software, simulate the high-voltage transmission signal to the pitch and disconnect the main power supply.

[0037] 2) Record the blade angle and voltage drop of the supercapacitor during the process.

[0038] 3) The data recorded and saved by the waveform recording software is organized as follows: Figure 1-3 .

[0039] High-speed wind data from a wind farm turbine test: See Figure 1 This is the data from 8 seconds after the main power supply was disconnected following grid connection. Figure 2 The data is for 10 seconds after the main power supply is disconnected from the grid. From the data collected for 8 seconds and 10 seconds after the main power supply is disconnected, it can be seen that during the period of disconnection, the blade angle did not change and remained at 0 degrees. The capacitor voltage did not show a significant downward trend until the unit was back in normal operation after the main power supply was closed. No fault was reported and the voltage did not change significantly.

[0040] Figure 3 The data is for 12 seconds after the main power supply is disconnected from the grid. It can be seen from the 12-second data of the main power supply disconnection that the pitch angle does not change and the capacitor voltage does not change significantly during the period of main power supply disconnection. After 12 seconds, the main power supply is closed and the unit reports a pitch power supply fault. The main control issues a pitch retraction command, and the blades retract from 0° to 89°. The capacitor voltage drops by about 2V.

[0041] 4) During normal unit operation, limit power to 400 kW. Manually disconnect the hub power switch until the blades have finished retracting, then close the hub power switch again. After simulating high-speed penetration, when an external 400V power supply failure occurs simultaneously, the data is as follows: Figure 4 . Figure 4 This is to simulate a 400V input fault test data for the pitch control system.

[0042] Twelve seconds after the hub power switch was disconnected, the unit reported a fault and the blades began to retract. Even after disconnecting the hub power switch, the unit could still run for 12 seconds before reporting a fault and stopping to retract the blades. The highest capacitor voltage loss was approximately 3.5V until feathering was completed.

[0043] 2. High wind test (backup)

[0044] Due to weather conditions, the wind speed required for a high-wind test was not met during the testing period, so the high-wind test was not conducted. The following alternative method was used instead.

[0045] Put the turbine into maintenance mode and lock the rotor into the hub. Switch one of the pitch control cabinet knobs to manual mode and manually control the pitch blades to approximately 0°. Then disconnect the input terminals of both chargers and record the initial voltage of the supercapacitor. Manually control the forward and backward movement of the blades, making them reciprocate between 0° and 3° for approximately 12 seconds. After the movement is complete, record the supercapacitor voltage value again, and then reconnect the charger input terminals.

[0046] The same steps were used to test the other two blades, and each shaft cabinet was tested twice.

[0047] The data is as follows:

[0048]

[0049] Note: During the test, the capacitor voltage dropped by less than 4V after the blades ran continuously for 12-15 seconds. The capacitor voltage was far from reaching the fault reporting threshold of 50V.

[0050] The implementation scheme of this invention has its own outstanding advantages in high voltage ride-through capability, has strong practicality and application value, and the test results generally meet the high voltage ride-through requirements. Within a controllable range, it can ensure the stable operation of the pitch system, reduce the fault occurrence area, reduce unnecessary waste of resources, identify the cause of the fault in a short time and repair it in a timely manner, avoid wind turbine grid disconnection accidents, and ensure the normal operation of the pitch system.

[0051] Finally, it should be noted that those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for high-altitude retrofitting of a wind turbine generator pitch control system, characterized in that, The high-voltage ride-through control bit is added to the communication protocol by the main control system. When the main control system detects a high voltage, it sets the high-voltage ride-through control bit to "1" and sends a high-voltage ride-through signal to the pitch control system, which then executes the high-voltage ride-through strategy. Conversely, if the high-voltage ride-through control bit is set to "0", the main control system does not send a high-voltage ride-through signal to the pitch control system, and the pitch control system executes the normal and non-high-voltage ride-through strategies. When executing the high-voltage ride-through strategy, if the power output can be restored within 12 seconds after the pitch control system receives the high-voltage ride-through signal command from the master control system, the pitch control system will not report a power failure; if the power output cannot be restored within 12 seconds after the pitch control system receives the high-voltage ride-through signal command from the master control system, the pitch control system will report a power failure. If the pitch control system does not issue a high-speed signal command, the pitch control system will report a power failure after 6 seconds. During high-voltage ride-through, the pitch control system makes the following adjustments: The backup power supply low voltage fault value has been adjusted from 40V to 50V. When the backup power supply voltage is lower than 50V, the pitch system will shut down unconditionally. During high-altitude traverse, the main power supply delay time is 12 seconds, while in non-high-altitude traverse, the main power supply delay time is 6 seconds. In both states, if the main power supply failure time exceeds the respective judgment time, the pitch system will shut down unconditionally.

2. The high-altitude retrofit method for a wind turbine generator pitch control system according to claim 1, characterized in that, After the blades are opened to 70 degrees via the main control system, a simulated high-speed transmission signal is sent to the pitch control system. The system disconnects the contactor and then activates the emergency stop. At this point, the safety chain disconnects and the blades automatically feather, proving that the emergency stop function is working properly during the simulated high-altitude crossing, ensuring the safety of subsequent tests.

3. The high-altitude retrofit method for a wind turbine generator pitch control system according to claim 1, characterized in that, The pitch control system is designed to disconnect the main power supply and be powered by a supercapacitor during high-altitude traverse. According to the high-altitude traverse requirements, the supercapacitor needs to provide power for a maximum of 12 seconds. At the same time, to ensure safety, the remaining capacity of the supercapacitor is required to ensure the safe retraction of the pitch unit after a unit failure.

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