Parameter Estimation of Resonant Fault Current Limiter for Protection and Stability Analysis

Aging or prolonged subjection to stressed conditions cause changes in the parameters of fault current limiter (FCL). These changes must be noticed to take remedial actions if necessary and to make sure whether the system fault current level is within the rated capacities of existing equipment or not. This paper presents a method for estimating parameters of a series resonant type FCL (RFCL) by using synchronized time-domain data from both ends of a transmission line. Estimated parameters during normal operation are used for protection and stability analysis of the system and fault data are used to analyze the performance of RFCL during fault. Electromagnetic transient line model is used to calculate the current and voltage across the device which are used to estimate the parameters of RFCL. PSCAD/EMTDC simulations are used to test the method. Applications of the parameter estimation method are also presented and as a demonstration, effect of variation in current limiting reactor on system transient stability is analyzed.