Characteristics Analysis Of Thyristor Controlled Series Capacitor (TCSC) And Development Of An Experimental Prototype

Thyristor controlled series capacitor (TCSC) is a kind of new power system equipmentdeveloped from the conventional fixed series capacitor. Its effective fundamental equivalentreactance can be controlled continuously by controlling the thyristor in a relatively largerange, either capacitive or inductive. As a novel method for electrical network control,TCSC can be utilized in the power system transient stability enhancement, power systemoscillation damping, the SSR mitigation and load flow control. It is of great importance to develop experimental setup of TCSC for the investigationof its basic operation characteristics and control countermeasure. Experimental setup mayacts physically similar to a real TCSC to a large extent with the advantage of ignoring therestrictions of system operation. Also, as the control system of the experimental setup ofTCSC could be the same as those used in the practical power system, controllers based onthe different theories can be tested and the performance of them can be verified before theirpractical use. This thesis is devoted to the operation characteristic analysis, system design,implementation and the test for the experimental setup of TCSC. Before designing of the setup, it is important to understand inter connection and theinteraction between the TCSC setup and the external power system operation condition.The thesis first investigate the operation characteristics of the TCSC under its ratedoperation conditions, the relation between system reactance and the related work conditionsof the TCSC, as well as the effect of the parameters of the composed elements in TCSC onits characteristics. The dual solution for the effective fundamental equivalent reactance of TCSC has beenfound when the limited power quality factor of the reactor is considered. Compared thefundamental equivalent reactance characteristic for two different synchronization methodsshow that dual solution phenomenon exists only when the line current synchronization isused. The reason causing the dual solution for the effective fundamental equivalentreactance of TCSC is found and verified by the digital simulations. TCSC is mainly used to control its fundamental equivalent reactance. Theeffectiveness of the TCSC is directly determined by the dynamic response of the equivalent IIIreactance. The effects of the synchronization methods of it on the dynamic response ofopen loop equivalent reactance are studied. Based on the results of the detailed transientprocess analysis, a close loop control scheme by adjusting the firing angle is presented. Thedigital simulation verified the effectiveness of the proposed scheme. Typical experimental power system with TCSC and its possible operation conditionsincluding the faulted state are investigated. Based on the investigation results, the ratingand the selection of the TCSC elements is performed. An open stile supervision and control system for the experimental TCSC setup isdeveloped. Basic functions of the industrial used TCSC as well as the additional functionsused for convenience testing are implemented in the system Details about the hardware andthe software of the system are given. A digital simulation model and an experimental setup of the together with a typicalexperimental simulation system including is established to test the performance of theTCSC. Digital simulation and experimental test results show that the correctness and theeffectiveness of the implemented setup of the TCSC.