Patent ID: 7616005

Claim:
A method of detecting imbalances in an electrical corrective device, connected to an electric power system, the method comprising: measuring a voltage V A , V B , and V C of each phase A, B, C of an electric power system; measuring a current I A , I B , and I C between each phase A, B, C of the electric power system and an electrical corrective device connected to the electric power system; calculating positive-sequence, negative-sequence, and zero-sequence device currents I 1 , I 2 , and I 0 , respectively, and positive-sequence, negative-sequence, and zero-sequence voltages V 1 , V 2 , and V 0 , respectively, on the basis of the currents I A , I B , and I C and the voltages V A , V B , and V C ; determining a predetermined negative-sequence current I 2un of an undamaged electrical corrective device; calculating a negative-sequence current difference by comparing the calculated negative-sequence current I 2 with the predetermined negative-sequence current I 2un ; comparing the negative-sequence current difference to a predetermined threshold; if the negative-sequence current difference exceeds the predetermined threshold, determining that an imbalance exists in the electrical corrective device; and de-energizing the electrical corrective device when an imbalance exists in the electrical corrective device.