Fuzzy Logic Control And Coordinated Control Apply To HVDC And AC/DC Systems

With the development of power system and our country's economy, Our country will implement the developing strategy of "the west power transmitted to the east area". At that time, several HVDC transmission lines will be built, there will appear large and complicated AC/DC Systems in our country. It will be practice and concrete of studying the problem of the HVDC control affecting the whole AC/DC systems' stability and the problem of the coordination among the many controllable components in the multi-infeed AC/DC systems.At present, the control method in HVDC systems is still the typical control theory based on the state equations. Although the traditional method has adaptability and robust to some extent, the dynamic characters of the actual system are not always satisfactory because that the actual AC/DC mixed systems are typical nonlinear and time-varying systems. So the classic control theory should integrate with the artificial intelligent technique in order to improve the dynamic characters of the whole AC/DC systems. The fuzzy logic control technique is one of the important branches of artificial intelligent technique.The AC/DC control problems and the background of this thesis are summarized in the first chapter, as well as the development of HVDC technique.In chapter 2, the control theory and the control method of HVDC system and its mathematic model are presented.In chapter 3, according to the characters of HVDC system, the auxiliary fuzzy logic control is added to the inverter in HVDC system by fuzzy logic reasoning in order to maintain invariance and stability of the direct current and improve the transient performance of the AC system.The study of how to use the HVDC system to improve the stability of AC system is stressed in chapter 4. In terms of the fuzzy logic reasoning based on the back function, a fuzzy logic controller is designed to improving the dynamic characters and enhancing the damping of AC system.In virtue of the fuzzy logic reasoning method and the algorithm of optimal decentralize and coordination, a intelligent fuzzy and decentralized and coordinated controller is designed in chapter 5, the controller is used to settle the coordination problem among the many controllable components and achieve the object that the minimal dynamic index of the whole AC/DC system.