A Novel Self-Adaptive Compensated Differential Protection Design Suitable for the Generator With Considerable Winding Distributed Capacitance

This paper presents a self-adaptive compensated differential protection of ac synchronous generators, particularly a type of high-voltage graded insulated cable wound generator, powerformer. The phase voltages at the terminals are utilized to estimate the capacitive currents when the generator is synchronized and no fault is detected. With the calculated capacitive current the capacitance distribution along with the winding of the generator can be determined. This capacitance will be equivalently arranged on the terminal and neutral of the generator respectively in a reasonable partition. Then, the capacitive current in the case of normal operation, external fault and internal fault can be calculated using the terminal voltage and the determined capacitance. It can be compensated to improve the reliability of the differential protection. The feasibility and effectiveness of the proposed scheme is proved with the simulation test results