一种发电机差动保护的新方案

比率制动式发电机差动保护在运行中的问题,主要是电流互感器在外部短路暂态过程中因为饱和效应可能产生误动作;此外,定子绕组短路时发电机一侧可能存在不大的穿越性电流,影响保护动作的灵敏性.本文提出一种改进的基于小矢量算法的发电机差动保护新方案.该方案根据内部故障和外部故障时故障电流特性的不同,使用小矢量算法,对故障性质做出初步判断,并根据不同的故障状态选择合适的制动电流.该方案与传统的差动保护方案相比,提高了可靠性和灵敏度.

A Novel Scheme of Generator Differential Protection

In terms of the problems occurred during the generator ratio restraint differential protection operating,owing to CT saturation caused by external short circuit transient fault,maloperation may be occurred in. Moreover,a certain amount of out-flow current may exist on the primary side of generator or transformer at short circuit fault on windings. It can decrease the sensitivity of the protection,and sometimes even bring the protection in non-operation. This paper presents a novel scheme of the generator differential protection. The phaselet component is used for judging whether an external fault or an internal fault is happened. After that different restraining currents are chosen. The simulation results prove that the new scheme of generator differential protection can ensure better sensitivity than traditional one during internal fault,and better security during external fault.