| Flexible Power Conditioner is a new style FACTS device, which can enhance power system stability. FPC can perform multi-functions including energy storage, active and reactive power generation. It can quickly and smoothly regulate the active and reactive power exchanging with connected power system. A back-to-back PWM rectifier is used as the excitation power supply. The converter used in FPC includes a grid side converter and a rotor side converter. Operating characteristics of the converter under steady and fault conditions is analyzed in this thesis.A three phase stationary frame based model and a two phase synchronously rotated frame based model are established. The state space averaging method is used to establish a continuous model. Direct current control method is used in VSC1 and voltage feedback control method is used in VSC2. Results are proved by simulation.Maximum power exchanged between converter and grid under grid symmetrical fault is analyzed. Basis is confirmed to choose source voltage. Rotor over current and control lose of capacitance voltage is analyzed. For ride-through operation of FPC under fault, a method is proposed. Its effectively is proved by simulation.Negative sequence and harmonic voltage and current appear when the grid voltage is asymmetrical. A method to restrain fluctuation of the capacitance voltage is proposed. The control of VSC2 is connected with the control of DFIG. A excitation method for DFIG is analyzed. As a result, a control method for VSC2 is proposed. At last, detection method of positive and negative sequence voltage and current is proposed. |
PDF Full Text Request