基于有功无功直流分量比值的变压器涌流新判据

针对变压器差动保护存在的区分励磁涌流和内部故障电流的难题,在引入瞬时无功功率理论的基础上,提出一种依据变压器各侧三相差有功功率和差无功功率直流分量比值的变化关系来识别变压器励磁涌流和内部故障电流的新方法.该方法原理简单,易于实现,具有数据采样方便、计算量小、动作可靠等特点.该方法从能量守恒的角度及有功功率和无功功率的关系出发,揭示了变压器励磁涌流和故障状态的本质不同.对变压器各种运行状态进行了实时数字仿真(RTDS)实验,仿真实验结果表明:该方法简单可靠,识别效果显著.

New Criterion to Identify Transformer Inrush Current Based on Ratio of DC Component of Real Power to Reactive Power

Discrimination between inrush current and internal fault current has been a challenging issue in power transformer protection.By introducing the theory of instantaneous reactive power,a new algorithm based on the variation of DC component ratio of real power to reactive power of transformer differential power is proposed to discriminate the transformer inrush current and the internal fault current.The proposed new method is of the characteristics of convenient data sampling,low computation cost and reliable operation,and is easy to realize.From the angle of conservation of energy and the relationship between real and reactive power,the essential difference between transformer inrush current and fault status is revealed.Results of RTDS simulation tests show that the proposed method is simple and reliable in providing distinct discrimination.