Research On Grid Connected Control Strategy For Permanent Magnet Synchronous Wind Power

Nowadays the problems of environment pollution and energy lack are more and more serious, and the utilization of renewable energy is attention of the people. Wind power is the most scale and most commercial of renewable energy technology. Wind power generation develop rapidly because of its cleanliness and free pollution. The technology of permanent magnet synchronous wind power generation is the research hotspot in wind power generation systems. This technology has many advantages, such as no boxes, few mechanical failure, high operational efficiency and low cost of maintenance, and so on. So it is very good of the future of the people.Firstly, this paper has analyzed the development of wind power technology and expounded several basic wind power operation modes. Then it has mainly discussed the structure characteristic and operation principle of the permanent magnet synchronous wind power system. The next this paper has analyzed and established the structure of the three-phase PWM converter device of wind power grid. And this paper has established mathematical model in the three-phase static coordinate system, two phase static coordinate system and two phase rotation of the three-phase PWM converter device.The different control strategies was been used in view of the different wind power systems grid topology structure in this paper. The strategy of direct power control was been used for the topology structure of the not controlled rectifier with voltage source PWM inverter. And this paper has introduced direct power control based on single switch table and double switch table. According to calculating the three-phase voltages and currents, this paper has calculated the active power and reactive power of the transmission system. The calculation results subtract the reference of the active power and reactive power, and then hysteresis compares, and outputs hysteresis control signal. The voltage signal has calculated go by two phase static coordinate system, and after the choice of sector, then output sector selection signal. This signal is been input switch table with hysteresis control signal. And then the switch table output switch signals of PWM. And then these signals can control the commutation of the PWM converter device. The simulation results show that this strategy can make the sine of the current and voltage, and realize independent regulation of the active power and reactive power.Finally, this paper has taken the voltage vector control strategy for the topology structure of the PWM rectifier with voltage source PWM inverter. This strategy can make active current and reactive current tracking reference value, and realize independent decoupling of the active power and reactive power. The simulation results show that the net runes in the work condition of the inverter when the system is normal operation. Then the system makes the wind power transfer to the grid effective and efficient. When the system appear voltage drop in the short time, the net inverter is in the running the mode of STATCOM. This control strategy can stable dc voltage and make up the reactive power to power grid. Then this strategy make wind power systems don’t split the connected grid because of the network voltage drop.