基于等值回路方程的变压器保护判据的研究

现有的基于变压器等值回路方程的保护原理不受励磁涌流的影响,但动作方程的选取及保护判据的整定尚未得到合理的解决.基于等值回路方程,利用一、二次绕组参数与短路参数的关系,推导出单相及三相双绕组、三绕组变压器的动作方程,提出以正序电流作为制动量的保护判据.与传统的设定单一门槛值的保护判据相比,该判据通过寻求动作量与制动量之间的关系,制定出动作曲线,提高了保护的灵敏性和可靠性.动模试验结果表明,该判据不受涌流的影响,在内部故障后一个半周期快速动作.

Research on Transformer Protection Criterion Based on Equivalent Circuit Equation

The existing transformer protection principle based on equivalent circuit equation casts off the influence of magnetizing inrush,however,reasonable operation equation and protection criterion have not been worked out.Based on equivalent circuit equation,utilizing the relations of first and second winding parameters and short circuit parameters,operation equations for single-phase and three-phase two-winding and three-winding transformer are derived from this principle.A protection criterion using positive sequence current as restraint portion is proposed.In contrast to the existing criterion,the new criterion improves sensitivity and reliability for protection by setting the action curve based on relationship between action value and resistance value.Test result indicates that it can escape from inrush current and can recognize the internal faults in one and a half cycles.