The wind energy known as "blue sky white coal" is an inexhaustible, clean and pollution-free renewable energy source, and its good prospects for development and utilization have received widespread attention from all countries in the world. In particular, with the application of computer technology and advanced control technology to the wind power field, wind power generation design and manufacturing technology has become increasingly sophisticated and has rapidly entered commercialization and industrialization. As one of the countries with abundant wind resources, China has made rapid progress in the localization of wind turbines. During the "Eighth Five-Year Plan" period, 200 kW/250 kW wind turbines were successfully developed and 600 kW stalled wind turbines were developed during the "Ninth Five-Year Plan" period. The key technology of wind turbine generator control systems was successfully developed. During the "10th Five-Year Plan" period, the 600kW stall-type wind turbines began to be industrialized, and the megawatt-level stalled and megawatt-class variable speed constant frequency have been listed as national scientific and technological projects. This article describes the industrialization project of 600kW stall-type wind turbines for the "Tenth Five-Year Plan" project. Based on the introduction of the control system, several key aspects of this key technology research for the wind turbine control system are highlighted. 2 Control system composition and function The control system is the core of the normal operation of the wind turbine. Its control technology is one of the key technologies of the wind turbine and it is closely related to other parts of the wind turbine. Its precise control and perfect function will directly affect the unit. Safety and efficiency. Therefore, the control system is a reliable guarantee for the normal and reliable operation of the entire unit and for optimal operation. The composition of the control system mainly includes: main circuit, control circuit, sensor and interface circuit. 2.1 System Components 2.1.1 Main Circuit The main circuit is the main power distribution system of a wind turbine generator system. It mainly completes the connections between generators and grids, reactive power compensation devices, soft grid-connected control devices, and various actuators and control loops. The main circuit provides a lot of power levels (such as 690VAC, 400VAC, motivation, power supply and other agencies operating status or feedback signals sent to the central controller for monitoring. 2.1.2 Control Circuit The control circuit consists of a central controller and its function extensions. Mainly to achieve input, output signal processing, logic function determination, issued a control command to the peripheral actuators, according to the signal processing and logic judgments to ensure the reliable operation of the various parts of the unit, at the same time through the configuration of the man-machine interface to see the data records, modify the operation Parameters and manual operation, the communication interface configured to communicate with the central monitoring system in real time. 2.1.3 Sensors and Interface Circuits The sensors mainly include current transformers and voltage transformers for monitoring power parameters; wind speed meters, wind vanes, Hall-type proximity switches, platinum thermal resistance, vibration acceleration sensors, and yaw counting sensors for wind parameters. Sensors that monitor the unit's status parameters such as trip switches, level switches, and pressure switches. The interface circuit converts the signals collected by some sensors into a unified standard signal through the interface circuit or is sent to the central controller for processing by means of communication. 2.2 System Function The control system mainly implements three functions: normal operation control, parameter monitoring and monitoring, and security protection and processing. The normal operation control includes wind generator automatic start soft-connected, automatic switching of large/small generators, generator heating, automatic yawing wind, automatic start/stop of hydraulic oil pump, automatic start/stop of gear oil pump, gear oil heater, and cooling Start-up and stop, automatic yawing and untwisting, automatic compensation for capacitor switching, and automatic shutdown of negative power. Parameter monitoring and monitoring includes power, wind parameters, hydraulic system status, yaw system status, soft grid connection, etc.; configuration of communication interface for central control room monitoring and remote monitoring, monitoring of operating status and fault conditions, and collection of fan operating data , Control instructions issued to the wind turbine. The safety protection and processing system is to ensure the safety and reliability of the operation process. It mainly includes brake protection when the unit fails, safety chain protection independent of the computer, protection of the device itself, grounding protection, and lightning protection. 3 Key technologies of the control system The control system of the wind turbine is a comprehensive control system. The control system not only monitors the grid, wind conditions and unit operating parameters, but also controls the grid connection and off-grid of the unit, and also changes the wind speed and wind direction. , Optimize the control of the unit. Therefore, the key technologies of the control system include the following major aspects: soft grid-connected control, yaw system control, reactive power compensation control, braking and safety protection, operation status parameter monitoring, local monitoring and remote monitoring. 3.1 Soft Grid Control Soft grid control technology is an important part of the control system. As wind turbines adopt squirrel-cage double-winding asynchronous generators, and if they do not take current limiting measures, they will have a strong impact on the wind turbines and the power grid. When the impact is severe, not only will the system voltage drop, but also Generators and mechanical components (such as towers, gear boxes) cause damage. Therefore, the use of soft grid-connected control can limit the transient currents of the generator during grid-connected and large/small motor switching so as to avoid excessive impact on the grid. The soft grid-connected control device adopts a bidirectional thyristor or thyristor anti-parallel connection, and the control method thereof is a voltage ramp soft grid-connected control mode. This method is evolved from the step-down start-up. It is controlled by thyristor phase-shift triggering to change the conduction angle of the thyristor so that the voltage applied to the stator of the motor gradually increases from a small initial value in the form of a staircase wave. Full pressure state, to achieve the purpose of pressure regulation and current limiting. The specific method is that when the generator speed is close to the synchronous speed, the triac directly connected to the power grid is turned on in step under the control of the gate trigger pulse, and the grid-connected inrush current is limited to 2 times the rated current of the motor. After the thyristor is completely turned on, the rotational speed exceeds the synchronous rotational speed and enters the power generation state. The bypass contactor short-circuits the two-way thyristor, and the wind turbine enters the steady state operation phase. The soft grid-connected control mainly includes the soft grid-connected small motor, the soft grid-connected large motor, the small motor switching to the large motor, the large motor switching to the small motor, and the small motor static electric start-up grid-connected. 3.2 Yaw system control The yaw system is a unique control system for wind turbines. The yaw control system is mainly composed of three parts: yaw measurement, yaw drive transmission, and cable protection device. Mainly to achieve two functions: First, the cabin to track changes in the stability of the wind direction; Second, due to the role of yaw leading to the nacelle internal cable winding and automatic unwinding. An automatic yaw is designed based on the wind vane to track the change of wind direction, and a 90* crosswind, central control room yaw, yaw of the control panel, and yawing of the top nacelle are designed according to specific control requirements. The yaw control sets the priority, and the priority from small to large is: automatic yaw controlled by the wind vane, yaw control by the central control room, yaw of the control panel, and yawing of the top cabin. The untwisting system automatically unwinds the cable according to the signal of the cable sensor when the cable is wound. The cable unwinding system is divided into two types: automatic cable unwinding controlled by a new cable sensor and safety chain protection controlled by a new cable switch. When the cable winding reaches the set value, the control system controls the yaw system to perform cable unwinding according to the signal sent from the cable sensor. If the control system does not perform the untwisting automatically, when the cable winding reaches the permissible limit, the safety chain protection of the cable switch is triggered, and the crew is shut down for emergency. 3.3 Reactive power compensation control The wind turbine generator set uses asynchronous generators. It must absorb the backward reactive power from the power grid for excitation, and at the same time the stator and rotor flux losses also consume reactive power. For power systems, reactive power mainly affects the grid voltage and increases line losses. When the power provided by the grid is insufficient, the quality of the power grid will be affected. Therefore, it is of great significance to carry out reactive power compensation to improve the power factor and improve the power quality of the wind turbine. The specific control idea is: using the method of parallel capacitors for reactive power compensation. It is divided into four levels for compensation. The four levels of capacity are: 87.5kvar, 50kvar, 25kvar and 12.5kvar. Capacitor switching can be controlled according to the active power generated by the generator. At the same time, in order to prevent frequent switching of the compensation capacitor. During the switching process, set the delay, and set a certain return value for the input and output power values. 3.4 Brake and safety protection Brake system and safety protection are the guarantee for the safe operation of wind turbines. The brake system is mainly composed of two parts, the tip air brake and the disc high speed brake. According to the type of failure of the wind turbine, the control system judges to perform alarm, normal shutdown, safety shutdown, and emergency shutdown respectively. At the same time, the wind turbine can be automatically restarted or started manually for self-resetting and non-resettable faults. The dual effect of safety and improving the availability of the unit; k independent of the safety chain of the computer is the use of anti-logic design, the supernormal failure that may cause fatal injury to the wind turbine, such as the computer system out of control and other series in a loop, once one action It will cause an emergency stop and the system will lose power. After an emergency stop occurs, it must be manually reset before restarting. The protection measures of the device itself mainly adopt hardware protection measures, such as adding RC absorption loops, hardware interlocking circuits, and over-voltage and over-current protection at both ends of the coil; the grounding protection mainly directly handles the control cabinet and the shielded cable layer; and it prevents lightning strikes. The protection mainly adopts lightning protection measures for the output of the main circuit, the input end of the electronic circuit, and the communication line, and is generally protected by an instantaneous absorption circuit. 3.S Operating status parameters Monitoring and monitoring Various wind turbine operating parameters during operation include power parameters, wind parameters, and status parameter monitoring. The power parameters that a wind turbine needs to continuously monitor include the three-phase voltage of the grid, the three-phase current output by the generator, the grid frequency, the power factor of the generator, the active power, and the reactive power. When the voltage is measured, it mainly detects the impact of power grid, over-voltage, over-current and power-off voltage. When measuring the current, it mainly detects current dropping, three-phase unbalance, etc. The wind parameters that the wind turbine needs to monitor are mainly wind speed and wind direction. 》The state parameters that need to be monitored include temperature, cabin vibration, New Zealand cable, system pressure, tip pressure, gear oil pressure, gear oil filter, and actuator feedback signals; among them, the rotation speed includes the rotation speed including the generator rotation speed and the impeller rotation speed; It mainly includes gearbox oil temperature, large generator temperature, small generator temperature, front bearing temperature, rear bearing temperature, ambient temperature, and control cabinet temperature. 3.6 On-site monitoring and remote monitoring The PC in the central control room is used as the upper computer. Multiple lower computer control systems (central controllers) are networked to communicate with the PC through dedicated communication devices and interface circuits. Real-time monitoring Wind turbine operating status, operating data, accumulated data storage, record fault conditions, statistical print statements, can also be yawing, reset, start, stop and other operations. Remote monitoring is through Modem or Industrial Ethernet, and communicates with the PC in the central control room to collect monitoring data from the PC in the central control room. Remote monitoring of multiple wind turbines is performed at a remote location (such as a fan manufacturer). 4 System Reliability Design The areas with abundant wind resources are usually remote areas, islands or even seas. The natural environment is rather harsh and requires unattended and remote monitoring. The requirements for the reliability and safety of the control system are relatively high. Therefore, when designing the control system, the central controller is generally selected to be used in the field of industrial control, especially to adapt to work in harsh natural environments, and to have strong real-time, reliability, and anti-jamming capabilities; The signal processing should adopt signal isolation measures and shielding protection; use hardware interlocks, instantaneous sensing over-voltage and other protection measures in the design of the hardware circuit; in terms of software design, the authority design of the software, task coordination design, fault-tolerant design, Anti-jamming design and program loops need to be considered. Cheap Measuring Tape,Steel Blade Tape Measure,Woodworking Measure Tape,Easy Read Measuring Tools Yucheng Weisite Measuring Tools Co., Ltd , https://www.wsttools.com