Wind Resource Concession Approach in China

Single-pole tripping of circuit breakers at the end of a transmission line for clearing LG fault (single phase to ground fault) produces high negative sequence current in nearby generators. Inserting a capacitor-connected between the ground and neutral of wye winding of a transformer at the end of the transmission line under open phase conditions-causes the net zero sequence reactance, which shunts the negative sequence network, to be zero. The negative sequence current is eliminated. The power transfer with one phase open, during single pole switching, becomes equal to pre-fault power and the transient stability limit is highly enhanced. Power swing is reduced.