Study On FACTS And Its Application For Improving The Comprehensive Performance In Wind Power And Power Grid

This paper is focused on the design of FACTS equipment and its application to the wind power, mainly for the asynchronous wind power generation system. It researched on the principle, design and simulation with EMTP. The main work is as follows:(1) A new dynamic reactive power compensation technique is proposed. The principle, control method, parameter design and performance are discussed. The entire control arithmetic is presented and proved, including DC voltage control, active and reactive current, and so on. The control strategy of DC voltage is designed based on the principle of power flow between the two sides of the convertor. The negative vector of the unbalance three-phase system is extracted and compensated in another dynamic var compensator. For a harmonic load which contains harmonic with certain characteristic frequencies, the characteristic harmonic current at the certain frequency can also be compensated after analysis on the harmonic load. So it can compensate the var current, negative vector and harmonic component together. The simulation results prove the good performance. The dynamic var compensation based on the algorithm can adjust its control methods by the load and the device through the analysis on the system. This design has great practical significance.(2) For the problem to detect the real-time information of frequency and phase, this paper analyzes the fundamental principle and performance of three-phase phase-locked loop, and the harmonic component in variable situations. It deducts the error influence on three-phase locked phase when the three-phase input signals are offsetting, unbalanced or harmonic in principle. The theoretical conclusions are confirmed by detailed simulations under these situations, such as offsetting, unbalance, harmonic, phase-abrupt, and frequency-abrupt. The three-phase phase-locked loop can work well in variable frequency system when the frequency of the inputs is variable.(3) The new-style dynamic var regulating invertor is used as the excitation regulator for the asynchronous wind power generator. The simulation is performed under different wind speed situations. The comparison of working effect is made between it and capacitor with fixed capacity. The results verify a quick, stable operation of this dynamic excitation regulator in reactive power compensation, and there are no serious inrush currents or overvoltages. The algorithm is proved too. (4) For the asynchronous wind power generator, a solution is presented as a variable speed wind turbines system, which is interconnected to power grid through rectifying circuit and inverter unit. A new-style equipment is also designed which can regulate the excitation current and eliminate the harmonic current. It can control the rectifier and inverter coordinately. In this proposed system, the rotating speed of the generator is variable, and the availability of both wind energy and generator is improved. The excitation regulating equipment can also eliminate the harmonic current caused by the rectifier and inverter, which can step down the detriment to the torque of the generator and improve the performance-cost ratio of the whole system.(5) It establishes an overall dynamic model for wind turbine set, including the equivalent model of machinery shafts, asynchronous generator and other parts. The parameters are calculated and confirmed. It studies basicly on the turbine generator shaft torsional oscillation between the wind-turbine machinery part and electric power.