【摘要】 在分析多起和应涌流引起变压器差动保护误动的现场实例的基础上,指出和应涌流引起差动保护误动一般是在和应涌流和电流互感器(current transformer,CT)暂态饱和的综合作用下发生的,并进一步分析了和应涌流引起差动保护误动的过程和特点。利用和应涌流先逐渐增大后缓慢衰减的波形特征,提出了基于判断差动电流基波幅值变化过程的和应涌流识别新方法。所提方法充分考虑了和应涌流的波形特征和误动原因,能在和应涌流引起CT暂态饱和之前快速可靠地对其加以识别,并采取有效闭锁措施来防止差动保护误动。仿真和动模试验验证了该方法的有效性和可行性。更多还原

【Abstract】 The analysis of some field mal-operation cases indicates that mal-operations of the transformer differential protection caused by sympathetic inrush usually occur under the combined action of sympathetic inrush and current transformer (CT) saturation. The process and characteristics of the mal-operation caused by sympathetic inrush are analyzed. According to the wave characteristics of sympathetic inrush that firstly increases to maximum gradually and then decays slowly, a new sympathetic inrush identification method is proposed, based on the calculation of the fundamental component increment of transformer differential current. The new method can identify sympathetic inrush quickly and reliably and adopt effective measures accordingly before sympathetic inrush makes CT saturated. The simulation and dynamic simulation experiment verifies the validity and feasibility of the method.更多还原