At present, the current small current connection device, mostly through an external voltage transformer, current transformer concentrates the zero sequence voltage of the substation and the zero sequence current of each outgoing switch. When the power grid occurs in a single phase failure, the fault line is judged by the ratio of the grade method, the phase method, or the ratio phase ratio phase. The correct line of the existing small current pickup device is less than 50%, and many power supply sectors are still using the larier method to determine the failover outline.
Our company has developed a high-voltage circuit breaker single-phase grounding protection and control system with independent intellectual property. The protection and control system and the circuit breaker body adopt integrated design. It collects three-phase currents on the switching line on the distribution line in real time. The voltage value, and extracts the fundamental wave of zero sequence voltage and zero sequence current, 3 times and 5 harmonics and zero-sequence power, according to the fault characteristics of single-phase fault, by zero-sequence voltage, zero-sequence current based base wave and 3 times and 5 harmonics are start-up values, and the zero-order power direction is determined, accurately determine the discharge device load side fault, send a single-phase protection alarm signal or give the protection trip command to realize single-phase alarm and protection .
This single-phase ground protection controller only needs to collect the electrical feature amount of this line, rather than centralizing the electrical feature amount of all outlines of the substation; when the line load side is uniformly fault, the single-phase ground protection controller can detect in time Out, issue alarm or protect the trip command; and when the power side of this line is single-phase failure, the circuit breaker does not operate, thereby achieving accurate identification failure, quickly locating the fault line.