RCCN WeChat QrCode
Mobile WebSite
This article briefly describes the entire wind power generation control system, and gives a detailed description of the basic functions of the wind power generation control system. Then, it briefly describes the current state of wind power generation technology and countermeasures in our plant, and finally briefly introduces the current wind power generation main direction.
A brief description of wind power control systemThe wind power control system includes on-site wind turbine control unit, high-speed ring-type redundant optical fiber Ethernet, and remote host computer operator station. The on-site wind turbine control unit is the core of the control of each wind turbine, which realizes the functions of parameter monitoring, automatic power generation control and equipment protection; each wind turbine is equipped with a local HMI human-machine interface to realize on-site operation, debugging and Maintain the unit; the high-speed ring-type redundant optical fiber Ethernet is the data highway of the system, which sends the real-time data of the unit to the upper computer interface; the upper computer operator station is the core of the operation monitoring of the wind power plant, and has complete unit status monitoring, Parameter alarm, real-time/historical data record display and other functions, the operator realizes the operation monitoring and operation of all units in the wind farm in the control room.
The wind turbine control unit (WPCU) is the control core of each wind turbine, which is distributed in the tower and nacelle of the unit. Due to the harsh operating environment of wind turbines, the reliability requirements of the control system are very high, and the wind power control system is specifically designed for the operation requirements of large wind farms. It should have extremely high environmental adaptability and anti-electromagnetic interference capabilities. The system structure is as follows:
The field control stations of the wind power control system include: tower main controller cabinet, nacelle control station cabinet, pitch system, converter system, on-site touch screen station, Ethernet switch, field bus communication network, UPS power supply, emergency shutdown backup system Wait. The network structure of the wind power control system is shown in Figure 1:
1. Tower control station
The tower control station, the main controller cabinet, is the core of the wind turbine equipment control, mainly including the controller, I/O modules, etc. The controller hardware adopts a 32-bit processor, and the system software adopts a strong real-time operating system. Various complex main control logics of the running unit communicate with the cabin controller cabinet, pitch system, and converter system through fieldbus. In order to make the unit run in the best condition.
The configuration of the controller adopts the configuration software with rich functions and friendly interface, and adopts the configuration method in accordance with the IEC61131-3 standard, including: function diagram (FBD), instruction list (LD), sequential function block (SFC), ladder diagram , Structured text and other configuration methods.
2. Engine room control station
The cabin control station collects the temperature, pressure, speed, and environmental parameters measured by the crew sensors, and communicates with the crew main control station through the field bus. The main controller controls the frame through the cabin to realize the crew's yaw and un-cable functions. In addition, It also controls various auxiliary motors, oil pumps, and fans in the engine room to make the unit work in the best condition.
3. Variable pitch system
Large-scale wind turbines above MW level usually adopt hydraulic pitch system or electric pitch system. The pitch system is controlled by the front-end controller to the pitch driving device of the three wind turbine blades. It is the execution unit of the main controller. It uses CANOPEN to communicate with the main controller to adjust the pitch of the three blades to work at the best status. The pitch system is protected by a backup power system and a safety chain to ensure emergency shutdown under critical conditions.
4. Converter system
Large-scale wind turbines currently generally use high-power converters to realize the conversion of power generation energy. The converter system communicates with the main controller through the field bus to realize the adjustment of the unit's speed, active power and reactive power.
5. On-site touch screen station
The on-site touch screen station is the on-site operation station for unit monitoring, which realizes the functions of on-site parameter setting, equipment debugging, and maintenance of the wind turbine unit. It is the on-site host computer operator station for the unit control system.
6. Ethernet switch (HUB)
The system adopts industrial-grade Ethernet switches to realize the connection between the controller of a single unit, the on-site touch screen and the remote control center network. The on-site cabinet adopts ordinary twisted-pair connection, and the remote control room upper computer adopts optical cable connection.
7. On-site communication network
The main controller has various types of fieldbus interfaces such as CANOPEN, PROFIBUS, MODBUS, and Ethernet, which can be configured according to the actual needs of the project.
8. UPS power supply
UPS power supply is used to ensure the power supply of the unit control system, emergency protection system and related execution units in the case of an external power failure.
9. Backup critical safety chain system
The backup critical safety chain system is independent of the hardware protection measures of the computer system. Even if the control system is abnormal, it will not affect the normal operation of the safety chain. The safety chain connects the abnormal faults that may cause fatal damage to the wind turbine into a loop. When the safety chain is activated, it will cause an emergency shutdown and the unit will be disconnected from the network, thereby maximizing the safety of the unit.
All wind turbines are connected to the upper computer operator station in the main control room through optical fiber Ethernet to realize remote monitoring of the entire wind farm. The upper computer monitoring software should have the following functions:
① The system has a friendly control interface. When compiling the monitoring software, fully consider the requirements of wind farm operation and management, and use Chinese menus to make the operation simple and as convenient as possible for the management of the wind farm.
② The system displays the operating data of each unit, such as the instantaneous power generation, cumulative power generation, power generation hours of each unit, rotation speed, wind speed, and wind direction of the wind turbine and motor, etc., and transfer these data from the lower computer to the upper computer. It is displayed on the monitor, and can be displayed intuitively in the form of a curve or a chart when necessary.
③ The system displays the operating status of each wind turbine unit, such as startup, parking, direction adjustment, manual/automatic control, and large/small generator operation, and learns the operation of the entire wind farm through the status of each wind turbine.
④ The system can promptly display the faults that occur during the operation of each unit. When the fault is displayed, the type and time of the fault can be displayed, so that the operating personnel can handle and eliminate the fault in time to ensure the safe and continuous operation of the wind turbine.
⑤ The system can achieve centralized control of wind turbines. In the centralized control room, the attendant only needs to operate the corresponding key indicating a certain function to change the setting state and control the lower computer. Such as start-up, shutdown and left-right direction adjustment. However, such operations have certain authority to ensure the safety of the entire wind farm.
⑥ System management. The monitoring software has the functions of timed printing and manual real-time printing of operating data and automatic fault recording, so as to check the historical record of the wind farm operation status at any time.
2. Basic functions of wind power control system
(1) Data acquisition (DAS) function: including collecting power grid, weather, unit parameters, and realizing control, alarm, recording, curve functions, etc.;
(2) Unit control functions: including automatic starting of the unit, grid-connected control, speed control, power control, reactive power compensation control, automatic wind control, untwisting control, automatic disconnection, safe shutdown control, etc.;
(3) Remote monitoring system functions: including the monitoring of unit parameters, related equipment status, historical and real-time curve functions, and cumulative monitoring of unit operating conditions.
1. Data acquisition (DAS) function
Related parameters monitored during unit operation include:
(1) Grid parameters, including grid three-phase voltage, three-phase current, grid frequency, power factor, etc. Voltage fault detection: grid voltage flicker, overvoltage, low voltage, voltage drop, phase sequence failure, three-phase asymmetry, etc.
(2) Meteorological parameters, including wind speed, wind direction, ambient temperature, etc.
(3) Unit status parameter detection, including: wind turbine speed, generator speed, generator coil temperature, generator front and rear bearing temperature, gear box oil temperature, gear box front and rear bearing temperature, hydraulic system oil temperature, oil pressure, oil level , Engine room vibration, cable twisting, engine room temperature, etc.
Both the upper computer and the tower touch screen station of the wind farm remote monitoring center can monitor the status of the unit, and realize the display, record, curve, alarm and other functions of related parameters.
2. Unit start and stop, power generation control
(1) The main control system detects grid parameters, meteorological parameters, and unit operating parameters. When the conditions are met, the yaw system is activated to perform automatic untwisting and wind control, release the brake disc of the unit, adjust the pitch angle, and the windmill starts to rotate freely To enter the standby state.
(2) When the wind speed monitored by the external weather system is greater than a certain value, the main control system starts the converter system to start the rotor excitation. When the generator stator output electric energy is at the same frequency, phase and amplitude as the grid, the closing outlet is open. The generator realizes grid-connected power generation.
(3) Wind turbine power and speed adjustment
According to the characteristics of the wind turbine, when the unit is operating at the best tip speed ratio λ, the wind turbine unit will capture the maximum energy. Although theoretically the unit speed can run at any speed, it is limited by the actual unit speed and system power. This stage has to be divided into the following operating areas: variable speed operating area, constant speed operating area and constant power operating area. The operating conditions within the rated power include: variable speed operating area (optimal λ) and constant speed operating area.
When the wind turbine is connected to the grid, the speed is lower than the limit speed and the power is lower than the rated power, according to the current actual wind speed, adjust the speed of the wind wheel to make the unit work in the state of capturing the maximum wind energy.
Because there is a certain error between the wind speed at the measuring point of the anemometer and the wind speed acting on the blades, the torque observer predicts the mechanical transmission torque of the wind turbine, and the rotation speed is derived from the corresponding relationship between the generator speed and the torque. ω is the expected value of generator speed. Tm is the observed value of torque. Kopt is the proportional constant at the optimal speed.
When the wind speed increases and the generator speed reaches the upper limit, the main controller needs to maintain a constant speed. The electric power generated by the wind turbine generator increases with the increase in wind speed. At this time, the turbine generator deviates from the optimal λ curve operation of the wind turbine.
When the wind speed continues to increase and the speed and power reach the upper limit, it enters the constant power operation area. In this state, the main control passes through the converter to maintain the unit power constant. On the one hand, 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 blades; on the other hand, the generator speed section is reduced through the converter to make the wind turbine run off the optimal λ curve and maintain the stable output power of the generator.
3. Logic of auxiliary equipment for wind power control system
(1) Generator system
Monitor the generator operating parameters, through 3 cooling fans and 4 electric heaters, control the generator coil temperature, bearing temperature, and slip ring chamber temperature within an appropriate range. The relevant logic is as follows:
When the generator temperature rises to a certain set value, start the cooling fan, when the temperature drops to a certain set value, stop the fan operation; when the generator temperature is too high or too low and exceeds the limit, an alarm signal is issued, and Perform safe shutdown procedures.
When the temperature drops to a certain set value, start the electric heater, when the temperature rises to a certain set value, stop the heater operation; at the same time, the electric heater is also used to control the temperature difference of the generator within a reasonable range Inside.
(2) Hydraulic system
The hydraulic system of the unit is used for yaw system brake and mechanical brake disc drive. When the unit is normal, it is necessary to maintain the operation in the rated pressure range.
The hydraulic pump controls the pressure of the hydraulic system. When the pressure drops to a set value, the oil pump starts to run, and when the pressure rises to a certain set value, the pump stops.
(3) Meteorological system
The meteorological system is an intelligent meteorological measuring instrument, which communicates with the controller through the RS485 port to collect the meteorological parameters outside the cabin to the control system. Control the heater of the meteorological measurement system according to the ambient temperature to prevent freezing.
Flashing obstruction light control, the end of each blade is installed with flashing obstruction light, which lights up at night.
The cabin fan controls the ambient temperature in the cabin.
(4) Electric pitch system
The pitch system includes the motor, driver, and 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 feathering control interface. The main functions of the pitch system are as follows: Emergency brake feathering system control, in an emergency, to achieve fan feathering control. Communicate with the main controller through the CAN communication interface and receive the main control command. The pitch system adjusts the pitch angle of the blades to a predetermined position. The communication content 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
Comprehensive fault status of the pitch system
The blades are feathered
Feathering command
(5) Speed increasing gearbox system
The gearbox system is used to increase the speed of the wind turbine to the normal operating range of the doubly-fed generator, and needs to monitor and control the gear oil pump, gear oil cooler, heater, lubricating oil pump, etc.
When the gear oil pressure is lower than the set value, start the gear oil pump; when the pressure is higher than the set value, stop the gear oil pump. When the pressure exceeds the limit, an alarm is issued and the shutdown procedure is executed.
Gear oil cooler/heater controls gear oil temperature: when the temperature is lower than the set value, the heater is started, when the temperature is higher than the set value, the heater is stopped; when the temperature is higher than a set value, the gear oil is started Cooler, when the temperature drops to the set value, stop the gear oil cooler.
The lubricating oil pump is controlled. When the lubricating oil pressure is lower than the set value, the lubricating oil pump is started, and when the oil pressure is higher than a certain set value, the lubricating oil pump is stopped.
(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 status and load signal of the unit, adjust the CW (clockwise) and CCW (counterclockwise) motors to achieve automatic wind and cable unwinding control.
Automatic wind control: When the unit is in operation or standby mode, the CW and CCW motors are adjusted according to the cabin angle and the deviation of the measured wind direction to realize automatic wind control. (Yaw at the set yaw speed, and the operating state of the yaw motor needs to be tested at the same time)
Automatic untwisting control: When the unit is in a suspended state, such as when the nacelle is twisted more than 720 degrees in a certain direction, the automatic untwisting program is started, or when the unit is running, if the twisting is greater than 1024 degrees, the untwisting program is realized.
(7) High-power converter communication
The main controller communicates with the converter through the CANOPEN communication bus. The converter realizes grid-connected/off-grid control, generator speed adjustment, active power control, and reactive power control:
On-grid and off-grid: The converter system controls the generator stator output electric energy to the same frequency, phase and amplitude according to the command of the master control by exciting the generator rotor, and then drives the stator outlet contactor to close to achieve parallelism. Grid; when the generating power of the unit is less than a certain value for a few seconds or the wind turbine or the power grid has an operating failure, the converter drives the generator stator outlet contactor to open to realize the off-grid of the unit.
Generator speed adjustment: When the generator is connected to the grid and runs below the rated load, the generator speed is controlled to achieve the optimal λ curve operation, and the wind turbine is used as an anemometer to measure the real-time torque value to adjust the generator to the best state run.
Power control: When the unit enters the constant power zone, it maintains the power determined by the unit output through the communication command with the inverter.
Reactive power control: Realize reactive power control or power factor adjustment through communication commands with the inverter.
8) Safety chain loop
The safety chain circuit is independent of the main control system and executes the emergency shutdown logic in parallel. All related drive circuits are powered by a backup battery to ensure the reliable execution of the system in an emergency state.
