Study On ASVG Based On New Type Voltage Modulation Strategy

Advanced Static Var Generator (ASVG) is an important FACTS controller, which has been applied in some power networks domestic and abroad. So far, most of the researches and applications have been carrying in the aspect of the design of main circuit, the detection method of reactive current, and the design of control strategy. Most of the current controlling strategies are based on the principle of equal height and unequal interval voltage superposition method, which has much disadvantage in practice. In this thesis the further analysis and research on ASVG is done, and a new modulation strategy is proposed.Firstly, the thesis analyzes the operating principle of ASVG briefly and summarizes the characteristics of ASVG. Compared with traditional reactive power compensation equipments, ASVG has the advantages of faster regulation speed and higher control accuracy. Besides, the performance of ASVG is better than that of synchronous regulating phase motor and SVC in the field of improving transient stability and damping of power systems.Thus, this thesis establishes the ASVG mathematic model which is used for the simulation and control of ASVG.Secondly, the control method for ASVG is studied and a new-type modulation method of ASVG is proposed in this thesis. The transformers with the uniform transformation ratio and capacity are connected directly in series on secondary side of the windings. For generating necessary sine waveform voltage in ASVG, a series of equal height and unequal interval rectangle waveform voltages are superposed, generated by switching inverting bridge circuit on and off by turns under the control of the specific algorithm. The ASVG sine waveform voltage injects into the power system directly or via step-up transformer. The result of mathematics simulation shows that the new type...