Investigation On The Model And Control Strategy Of Thyristor Controlled Series Capacitor (TCSC)

TCSC (Thyristor Controlled Series Capacitor) is one kind of FACTS (Flexible Alternating Current Transmission System) device, and so far it is the only one which has been practically used in the projects for the reasons that it is simple in structure and inexpensive in cost. Compared with the FSC (Fixed Series Compensation), with it's ability of large-scale smooth regulation of the impedance by changing the trigger angle of the thyristor, it has the advantages of enhancing the transient stability and restraining the LFO (Low Frequency Oscillation) and SSO (SubSynchronous Oscillation).This thesis describes the basic configuration and the operation principle of TCSC. Based on this, it analyses the factors which affects the range of the compensation and limitations in the operation of the TCSC. After that, the thesis introduces a scheme of establishing a control and monitory system based on the requirements of project Dynamic Simulation TCSC for the LAB of ShanDong University.As control of the TCSC plays a very important role, this dissertation focuses its attention on the designing of a controller for the TCSC based on the artificial intelligence principle. It is actually a three layer control system.In chapter 3, the author analyses the controlling strategy for the bottom layer controller and summarizes the methods suit to the angle triggering and the region switching. Then, the mechanism of TCSC to enhance the transient stability of power system in analyzed. At last, the reason of why the TCSC can restrain the LFO is given by use of the plural coefficient torque method.In chapter 4,a controller for TCSC based on the SNN (Single Neural Network) for a SGIB (Single Generator Infinite Bus) power system is proposed. Simulation results show that the SNN based controller is able to enhance system stable and to improve the robust of the controller as well. In chapter 5, a three-order dynamic model of a SGIB system for TCSC application is given at first. Then, a TCSC with a new kind PID controller based on the theory of fuzzy logic theory is used. The simulation results shows that the fuzzy-pid controller is robust. The transient stability of power system is significantly improved. However, this kind of controller has a disadvantage in selecting an appropriate membership function. This is a subject for the further investigation..