Design and analysis on overvoltage protection circuit topology of resonance fault current limiter

The resonance fault current limiter (RFCL) is a practical way to solve the problem of the bulk fault current on the EHV. The capacitor will endure overvoltage for the fault current. Traditional ways of overvoltage protection are not meeting with the RFCL needs. The new type of overvoltage protection circuit is introduced. The protective equipment consisted with thyristor, gap and bypass breaker. The characters of equipment are not the same so that they have different damping circuit topology. Mathematical model of topology circuit is built to analyze the current strength. Thus the structure is optimized. Damping parameters also affect the current gradient and surge time. They are ranged in numerical value through lots of simulation. Fault current and discharging current of capacitor would give more current strength to the thyristor. The transient temperature changed by the current strength is analyzed through Cauer model. Simulation proved the theory correct and practical.