谐波闭锁在抑制电流互感器饱和对差动保护影响方面的应用

摘要

This paper investigated the impact of current-transformer(CT) saturation on transformer differential relays,and built harmonic blocking model.Then,the model's accuracy was verified with CT simulations,relay secondary injections,and high current primary injections.The simulations and results demonstrate that the slope characteristic only can not provide sufficient safety,and there is great need to activate harmonic blocking to trip relay with higher sensitivity to internal faults and turns faults when CT saturates during through-faults.In addition to improving protection sensitivity,harmonic blocking can provide adequate safety for spurious trip introduced by CT saturation by simplifying protection calculation.%针对电流互感器(CT)饱和对变压器差动继电器的影响,建立由CT饱和引起的谐波闭锁模型,用CT仿真、继电器二次注入和大电流一次注入方式来验证模型的精度.结果表明,击穿故障期间,当CT饱和时,仅使用斜率特性并不能提供足够的安全保障,还需激活谐波闭锁使继电器跳闸.谐波闭锁对内部故障和匝间故障具有更高的灵敏度,能有效提供安全保障;此外,谐波闭锁简化了保护设定计算,为防止由CT饱和引起的误动操作提供有效的保障.