The over-voltage analysis and protection measure determination of thyristor controlled reactance series compensation by adjustable coupling

The overvoltage analysis and confirmation of the protection measure for different short-circuit faults can ensure safe operation of thyristor controlled reactance series compensation device. A characteristics parameters analysis method is proposed. By use of characteristics parameters of circuit it can identify fault spots with serious overvoltage. In view of these fault spots, thyristor control method to reduce overvoltage and over-current is obtained. Furthermore the overvoltage protection measure of TCSCAC is presented. Electromagnetic transient program PSCAD/EMTDC is used to simulate overvoltage, as well as over-current and protection measure effect of serious fault spot. Analysis results show that the characteristics parameters method can quickly and accurately estimate the overvoltage level for short-circuit faults. After thyristor control and protection measure are adopted, the overvoltage level, over-current level and MOV energy consumption drop remarkably. Expenses of overvoltage protection are reduced greatly.