Basic functions of the second wind power control system
(1) Data collection (DAS) function: including collecting power grid, meteorological, and unit parameters to realize control, alarm, recording, and curve functions;
(2) Unit control functions: including automatic start unit, grid connection control, speed control, power control, reactive power compensation control, automatic air control, cable removal control, automatic off-network, and safe shutdown control;
(3) Remote monitoring system functions: including unit parameters, monitoring of related equipment status, historical and real-time curve functions, and cumulative monitoring of unit operating conditions.
1, data acquisition (DAS) function
The relevant parameters for monitoring during the operation of the unit include:
(1) Grid parameters, including grid three-phase voltage, three-phase current, grid frequency, power factor, etc. Voltage fault detection: grid voltage flicker, over voltage, low voltage, voltage drop, phase sequence fault, three-phase asymmetry, etc.
(2) Meteorological parameters, including wind speed, wind direction, ambient temperature, etc.
(3) Unit status parameter detection, including: rotor speed, generator speed, generator coil temperature, generator front and rear bearing temperature, gearbox oil temperature, gearbox front and rear bearing temperature, hydraulic system oil temperature, oil pressure, oil level , cabin vibration, cable turn, cabin temperature, etc.
The upper computer of the wind farm remote monitoring center and the tower touch screen station can realize the status monitoring of the unit, and realize the functions of displaying, recording, curve and alarm of relevant parameters.
2. Unit start and stop, power generation control
(1) The main control system detects the grid parameters, meteorological parameters, and unit operating parameters. When the conditions are met, the yaw system is activated to perform automatic cable unwinding and wind control, releasing the brake discs of the unit, adjusting the pitch angle, and the windmill begins to rotate freely. , enter the standby state.
(2) When the wind speed monitored by the external meteorological system is greater than a certain value, the main control system starts the converter system to start the rotor excitation. When the output power of the generator stator is the same frequency, the same phase and the same amplitude as the grid, the closing of the closing outlet The device realizes grid-connected power generation.
(3) Wind turbine power and speed adjustment
According to the characteristics of the wind turbine, when the unit is in the optimal tip speed ratio λ, the fan unit will capture the maximum energy. Although the unit speed can theoretically run at any speed, it is limited by the actual unit speed and the system power limit. The stage has to be divided into the following operating areas: the variable speed operating area, the constant speed operating area and the constant power operating area. Operating conditions within rated power include: variable speed operating zone (optimum λ) and constant speed operating zone.
When the fan is connected to the grid, if the speed is less than the limit speed and the power is lower than the rated power, adjust the speed of the wind wheel according to the current actual wind speed, so that the unit works in the state of capturing the maximum wind energy.
Since there is a certain error between the wind speed at the measuring point of the anemometer and the wind speed acting on the blade, the torque observer predicts the mechanical transmission torque of the wind turbine, and the rotational speed is introduced through the corresponding relationship between the rotational speed of the generator and the torque. ω is the expected value of the generator speed. Tm is the observed value of the torque. Kopt is the proportionality constant at the optimum speed.
When the wind speed increases and the generator speed reaches the upper limit, the main controller needs to maintain the constant speed. The electric power generated by the wind turbine increases with the increase of the wind speed. At this time, the unit deviates from the optimal λ curve of the wind turbine.
When the wind speed continues to increase, so that the speed and power reach the upper limit, enter the constant power operation zone. In this state, the main control passes through the converter to maintain the power of the unit constant, and the main controller reduces the wind power through the adjustment of the pitch system. The angle of attack reduces the capture of wind energy by the blade; on the other hand, the generator speed is reduced by the converter, so that the wind turbine deviates from the optimal λ curve and the output power of the generator is kept stable.
3, wind power control system auxiliary equipment logic
(1) Generator system
Monitor the generator operating parameters, control the generator coil temperature, bearing temperature, and slip ring chamber temperature in an appropriate range through 3 cooling fans and 4 electric heaters. The relevant logic is as follows:
When the temperature of the generator rises to a certain set value, the cooling fan is started. When the temperature drops to a certain set value, the fan operation is stopped; when the temperature of the generator is too high or too low and exceeds the limit, an alarm signal is issued, and Perform a safe shutdown procedure.
When the temperature is lower to a certain set value, the electric heater is started, and when the temperature rises to a certain set value, the heater operation is stopped; at the same time, the electric heater is also used to control the temperature end difference of the generator within a reasonable range. Inside.
(2) Hydraulic system
The hydraulic system of the unit is used for yaw system braking and mechanical brake disc drive. When the unit is normal, it is necessary to maintain the rated pressure range.
The hydraulic pump controls the hydraulic system pressure. When the pressure drops to the set value, the oil pump is started. When the pressure rises to a certain set value, the pump is stopped. (3) Meteorological system
The meteorological system is an intelligent meteorological measurement instrument that communicates with the controller through the RS485 port and collects meteorological parameters outside the cabin to the control system. The heater of the meteorological measurement system is controlled according to the ambient temperature to prevent icing.
The flashing obstacle light is controlled, and a flashing obstacle light is installed at the end of each blade to light up at night.
The cabin fan controls the ambient temperature inside the cabin.
(4) Electric pitch system
The pitch system includes the motor, the driver, and the main control PLC on each blade. The PLC communicates with the main control system of the unit through the CAN bus. It is the pitch adjustment control unit in the wind power control system. The pitch system has Backup DO feather control interface. The main functions of the pitch system are as follows: emergency brake feathering system control, in the case of emergency, fan blower control. The main communication command is accepted through communication with the main controller through the CAN communication interface, and the pitch system adjusts the pitch angle of the blade to a predetermined position. The communication between the pitch system and the main controller includes:
Blade A position feedback
Blade B position feedback
Blade C position feedback
Blade pitch given command
Pitch system integrated fault status
Blade in feathered state
Feather command
(5) Speed increasing gearbox system
The gearbox system is used to increase the speed of the wind turbine to the normal speed operating range of the doubly-fed generator. It is necessary to monitor and control the gear oil pump, gear oil cooler, heater, lubricating oil pump and so on.
When the gear oil pressure is lower than the set value, the gear oil pump is started; when the pressure is higher than the set value, the gear oil pump is stopped. When the pressure is exceeded, an alarm is issued and the shutdown procedure is executed.
Gear oil cooler / heater control gear oil temperature: When the temperature is lower than the set value, start the heater, stop the heater when the temperature is higher than the set value; when the temperature is higher than a set value, start the gear oil The cooler stops the gear oil cooler when the temperature drops to the set value.
Lubricating oil pump control, when the lubricating oil pressure is lower than the set value, start the lubricating oil pump, when the oil pressure is higher than a certain set value, stop the lubricating oil pump.
(6) yaw system control
According to the current cabin angle and the measured low-frequency average wind direction signal value, as well as the current operating state and load signal of the unit, the CW (clockwise) and CCW (counterclockwise) motors are adjusted to realize automatic wind and cable unwinding control.
Automatic wind control: When the unit is in running state or standby state, the CW and CCW motors are adjusted according to the deviation of the cabin angle and the measured wind direction to realize automatic wind adjustment. (The yaw is performed at the set yaw speed, and the running state of the yaw motor needs to be detected)
Automatic cable unwinding control: When the unit is in the pause state, if the cabin is twisted more than 720 degrees in a certain direction, the automatic cable unwinding procedure is started, or when the unit is in the running state, if the twist is greater than 1024 degrees, the cable unwinding procedure is realized.
(7) High-power converter communication
The main controller communicates with the converter through the CANOPEN communication bus, and the converter realizes grid-connected/off-network control, generator speed regulation, active power control, and reactive power control:
Grid-connected and off-grid: The converter system controls the output power of the generator stator to the same frequency, in phase, and the same amplitude according to the command of the main control, and then drives the stator outlet contactor to close. When the generating power of the unit is less than a certain value for several seconds or when the fan or the power grid fails to operate, the converter drives the stator exit contactor of the generator to open, and the unit is disconnected.
Generator speed regulation: When the unit is running in the following stage of rated load, the unit is operated at the optimal λ curve by controlling the generator speed. By measuring the real-time torque value as an anemometer, the unit is adjusted to the optimal state. run.
Power control: When the unit enters the constant power zone, it maintains the power of the unit output through the communication command with the inverter.
Reactive power control: Reactive power control or power factor adjustment through communication commands with the inverter.
8) Safety chain circuit
The safety chain loop is independent of the main control system and executes the emergency shutdown logic in parallel. All relevant drive circuits are backed up by the backup battery to ensure reliable execution of the system in an emergency.
