The wind turbine controller plays a key role in safe and efficient energy conversion. The control system consists of sensors, actuators, and software and hardware processors. The actuators include hydraulic or electric drive devices. The processor system uses a reliable hardware safety chain. Its functions include data collection and processing, variable speed control, speed control, automatic maximum power point tracking control, power factor control, yaw control, automatic unloading, grid connection and outage control, parking brake control, safety protection system, and local monitoring. and remote monitoring to ensure optimized performance and safe operation.
1、Wind turbine composition-control system
（1）Integral Role of Wind Turbine Control System in Safe and Efficient Energy Conversion
The control system of the wind turbine unit runs through every part of the unit and is directly related to the safe and economical operation of the unit.
The main function of the control system is to obtain as much wind energy as possible while ensuring the safe operation of the wind turbine and convert it into electrical energy efficiently.
（2）Components and Functions of the Wind Turbine Control System
The wind turbine control system consists of sensors, actuators and software/hardware processors. The processor is responsible for processing the sensor input signal and sending out an output signal to control the action of the actuator.
The sensor is responsible for collecting signals, generally including rotation speed, power, position, vibration, temperature, pressure sensors, anemometer, wind vane, operating switches, buttons and other devices.
（3）Actuators and Processor System in Ensuring Safety and Reliability
The actuator includes hydraulic or electric drive devices, torque control, grid connection, braking, and yaw motor. The processor system uses a computer or microcontroller with a reliable hardware safety chain for wind turbine control functions.
When a serious failure occurs in the unit, the control system can ensure that the unit is in a safe state.
（4）Comprehensive Control Functions of Wind Turbine Control System for Optimal Performance and Safety
The specific control contents of the control system include data collection and processing, variable speed control, speed control, automatic maximum power point tracking control, power factor control, yaw control, automatic uncapping, grid connection and decommissioning control, parking brake control, safety Protection system, local monitoring, remote monitoring, etc.
2、Pitch control system
The variable pitch control system adjusts blade angles based on instructions from the main controller. It controls power, startup, shutdown, and emergency shutdown. During startup, pitch angles gradually adjust for maximum torque. Below rated power, pitch angle remains at zero degrees. At rated power, pitch angles adjust to maintain constant output. Pitch angle information is obtained through a counter or encoder. The system ensures aerodynamic shutdown during unit failure. It pitches blades to 90 degrees for normal and emergency shutdown, ensuring safety.
3、Power control system
（1）Wind Farm Automatic Generation Control
Wind turbines allocate active power based on grid instructions and output characteristics, achieving closed-loop control. This ensures wind farm’s active output meets grid control requirements.
（2）Wind Farm Primary Frequency Control
When the frequency of the power system deviates from the specified frequency regulation dead zone, the wind farm quickly and automatically adjusts the active power to respond to changes in the grid frequency and maintain the stability of the grid frequency.
（3）Wind Farm Power Control System
A system that realizes functions such as automatic power generation control, primary frequency regulation control and reactive power voltage control of wind farms through direct control of wind turbines and reactive power compensation devices.
4、Yaw control system
(1) Automatic wind control during normal operation
When the engine room deviates from the wind direction at a certain Angle, the control system issues clockwise or counterclockwise yaw instructions according to the control strategy, controls the position of the engine room to the dynamic wind, and then stops the yaw.
(2) Automatic release of cable when twisted
When cumulative engine room deflection reaches the set value, the control system stops fan operation to prevent excessive cable distortion. The engine room rotates in the opposite direction to unwind cables. If yaw twist angle is too large, limit switch triggers emergency fan stoppage, requiring manual cable unhooking.
(3) Some fans are also equipped with overspeed automatic crosswind function
When the wind wheel speed exceeds the set value and the control system cannot reduce the speed, the yaw system will yaw the engine room 90° from the main wind direction, and the fan will lose wind energy after the crosswind to reduce the fan damage.
5、Security protection system
When the wind speed, ambient temperature and other conditions exceed the limit, manual shutdown is required or the unit itself encounters a non-emergency shutdown failure, the control system will perform a normal shutdown based on the control strategy.
When the wind turbine is shut down normally, the control system controls the blade pitch device to pneumatically retract the blades. When the power drops to the set value, the main circuit breaker is disconnected from the grid. After the shutdown conditions are eliminated, wind turbines can often resume operation automatically.
When the control system detects an emergency shutdown fault, it will trigger a quick shutdown program. At this time, the control system will pneumatically retract the propellers at a faster speed.
When the power drops to the set value, the main circuit breaker will be disconnected from the grid. When the spindle speed is The mechanical brake is activated below the specified value.
In order to ensure the safety of wind turbines, key protection nodes are connected in series in the form of a safety chain to form a hardware protection loop that is independent of the control system.
Generally speaking, emergency stop of the converter, emergency stop of the pitch system, emergency stop of the tower base cabinet, emergency stop of the engine room cabinet, overspeed, vibration exceeding the limit, and twisting cable exceeding the limit will trigger the safety chain protection action.
The propellers are retracted at a certain speed, the converter is disconnected from the grid, and the mechanical brake is applied. When personal safety is endangered, the internal power supply of the unit may be cut off.
Learn More：State-of-the-art in wind turbine control: Trends and challenges – ScienceDirect
