The Study On Power Differential Bus Protection

With the development of intelligent electric equipments, especially the intelligent switch, photoelectric transformer, etc.Digital substation has been the main aspect of substation automatization system. Current differential principle is a basical busbar protection theory and is widely used. But in digital substations, there are some difficulties to apply current differential principle. This paper proposes a new principle bus protection scheme, power differential protection.In the power differential protection scheme, active power is a constant, so it is not affected by asynchronous clock. It is proved by simulation results that the power differential protection scheme is practical. The power differential protection scheme provides a way that is not affected by asynchronous clock, and it makes up for a deficiency, that is the current differential protection must be locked when the clock is asynchronous.