Recently, China Shenhua’s Shendong Coal was granted a national invention patent for its Phase Sequence Identification Device. This patent resolves the persistent industry challenge of incorrect phase sequence wiring in the microprocessor-based protection devices of underground high-voltage distribution equipment in coal mines. It offers a novel technical solution for enhancing the safety and stability of underground power supply systems and fills a technological gap in the field of online automatic phase sequence identification and adjustment for mining microprocessor-based protectors.
Mining high-voltage explosion-proof switchgear fitted with intelligent microprocessor-based comprehensive protectors constitutes critical equipment for underground power supply safety. The protector’s calculations for protection logic, active power, and electrical energy all rely on accurate voltage and current phase sequences. During equipment installation and retrofit work, unclear wiring diagrams and illegible cable markings can easily result in incorrect voltage and current phase sequence connections. Conventional corrective measures require a power shutdown, entry underground, cover removal, and rewiring, or alternatively, manual adjustment of sampling channels by technicians based on recorded waveform data. These methods are not only labor-intensive but also cause production downtime. For certain critical loads where power outages are not permissible, phase sequence errors cannot be addressed promptly, potentially leading to protection device misoperation or non-operation, distortion of power metering and energy consumption data, and ultimately hindering the advancement of intelligent and automatic mining operations.
To tackle this common industry problem, Shendong Coal has developed two innovative methods: the PSEV voltage phase-shift eigenvalue identification method and the PSEC current phase-shift eigenvalue identification method. This solution makes full use of the existing hardware in mining microprocessor-based protectors, requiring no additional equipment, and strikes a balance between technological innovation and practical site applicability. Once implemented, it can effectively prevent protection anomalies caused by phase sequence errors, reduce the need for power-off maintenance, lower underground maintenance workloads, and ensure the accuracy and reliability of protection, metering, and energy monitoring data, improving the intrinsic safety of underground power systems.
