Power Based Open Phase Condition Detection Scheme

Abstract

Open phase condition can occur in all types of power plants and substations, of which the detection and treatment measures are beginning to be required in the design standards of nuclear power plants. Operation experience shows that when open phase condition occurs on the primary side of the transformer, especially under light and no-load conditions, the traditional protection device based on sequence components cannot reliably operate, and the safety equipment that is used to isolate station auxiliaray transformer will not work properly, which leads to the failure of safe bus automatically transfered to a stanby power source. This situation posts great threats to the safe operation of nuclear power plants. This article systematically analyzes the difficulties in open-phase detection and the change in electrical quantities after open phase fault, and more importantly, focuses on the analysis of the power characteristics after the fault, based on which a new open phase detection scheme for nuclear power plants is proposed. It can also be applied to other types of power plants. The method and its feasibility are verified on PSCAD simulation software. The paper provides a new idea for the detection of open phase fault.