TRVs across circuit breakers of series compensated lines-status with present technology and analysis for the Turkish 420 kV grid

Analysis is made of TRVs (transient recovery voltages) across circuit breakers of EHV lines compensate with modern series capacitors protected by varistors. A physical explanation of the phenomenon is presented first. This is useful for classifying the series compensation transmission schemes on the basis of the TRV magnification they can cause. Means are reviewed for limiting TRVs (opening resistors, by-passing of capacitors, surge arresters, etc.). An attractive and novel solution is explored, namely varistors branched across line breaker contacts. Results are presented of EMTP TRV analysis performed for three groups of series compensated 420 kV lines in Turkey, and a description is given of measures applied for limiting TRVs