Evaluation of Circuit Breaker Capability for Reignition Free Operation of 400kv Shunt Reactor and 765kv Shunt Reactor with Ngr Using Controlled Switching Device

The shunt reactor is a key element in the Extra High Voltage (EHV) power system used for voltage regulation. The current drawn by the reactor is highly inductive; due to this feature, it presents constraints in current interruption by circuit breakers. The current can resume after interruption if the rate of rise of dielectric strength (RRDS) of the dielectric medium is lower than the rise time derivative of the recovery voltage and can result in an unsuccessful current interruption. Based on this consideration, minimum arcing time is prescribed by Circuit Breaker (CB) manufacturers. Evaluation of the re-ignition free window for the EHV 420kV 80Mvar shunt reactor has been carried out in this paper as per the procedure laid out in IEC-62271-100 and IEEE-035-017 with the help of PSCAD-EMTDC software package. The results are well supported by field-implemented disturbance records of controlled switching opening operation. The effect of the presence of a surge arrester on Transient Recovery Voltage (TRV) has been considered and elaborated. The effect of the presence of a neutral grounding reactor (NGR) with a 765kV Shunt reactor is also discussed in this paper. The presence of NGR tends to increase the peak of TRV peak and the same has been calculated through simulations, the field results are then discussed based on the re-ignition free window calculated as per IEC 62271–100. Optimum controlled switching helps in the reduction of mechanical and electromagnetic stresses generated during random switching operations of the reactor. The simulation results and field reports are in good agreement and controlled switching helps in meeting the opening targets within a re-ignition free window with fair accuracy.