Analysis of Non-Full-Phase Operation Incidents and Recommendations for Fault Handling

Non-full-phase operation, as a typical abnormal condition in power systems, can easily lead to increased zero-sequence currents and neutral point voltage shifts, posing a significant threat to the safe and stable operation of the power grid. This paper systematically reviews the entire process—from fault occurrence and alarm reporting to on-site inspection and dispatch handling—based on an actual case of a line non-full-phase fault during bus switching operations at a 220kV substation. It also conducts a theoretical analysis of zero-sequence network characteristics under longitudinal faults using an equivalent model of non-full-phase operation for bus tie circuit breakers. Research findings indicate that the distribution of zero-sequence currents generated by non-full-phase operation is jointly influenced by neutral grounding methods, network structure, and load levels. Improper handling may easily lead to protection misoperation. Finally, this paper proposes clear, operationally feasible dispatch handling procedures and precautions for non-full-phase faults in line/main transformer circuit breakers and bus tie circuit breakers, respectively. These aim to provide reference for on-site operation and dispatch command, enhancing the grid''s safety control capabilities in responding to non-full-phase faults.