Influence of combined protective circuit parameters on protective effect of breaking overvoltage for shunt reactor

In order to ensure that the overvoltage caused in the process where cuts off the dry-type air-core shunt reactor falls within a reasonable range, this paper studies the effects of the combined protective circuit parameters on the breaking overvoltage when cutting off shunt reactors, by theoretical analysis and simulation methods. Based on the circuit theory, breaking overvoltage is theoretically analyzed. Based on the ATP-EMTP software, the circuit breaker, reactor and arrester model are established, the breaking overvoltage of the reactor is studied at different action time of the breaker under different cut-off current values. The results show that for the CKK-108/10-6 dry-type air-core reactor, the value of the resistor in the combined protective circuit mainly affects the re-ignition overvoltage. Re-ignition overvoltage decreases first and then increases with the increase of the resistance value. When the resistance value is set as 200Ω, re-ignition overvoltage has reached the lowest value, which is not higher than 2.8p.u. The value selection of the capacitor affects both the cut-off overvoltage and re-ignition overvoltage. The greater value of the capacitor is, the better overvoltage suppression effect is. The arrester starts when the cut-off value is 20A. The value of each parameter of the combined protective circuit has a great influence on the protection effect, and only the reasonable parameter selection can achieve the purpose of suppressing the overvoltage.