Single‐Switch Open‐Circuit Fault Diagnosis Based on Error Current for Active Power Filter

ABSTRACT This paper presents a fault diagnosis method based on the error current for active power filter (APF) to enhance reliability. APF have significant practical significance and application value because they can be used to solve power quality problems such as harmonics, reactive power or negative sequence existing in the power system. First, the expression of error current is educed which is analysed by the influence of different open‐circuit faults on the shunt three‐phase three‐level APF. Based on this, we analyse the differences in error current of the harmonic compensator when it is in normal operation and under different fault conditions, and then construct fault diagnosis variables. In addition, the relationship between the value of the fault diagnosis variable and fault type is built and the fault diagnosis method is proposed to detect the open‐circuit fault and locate the faulty switches. Finally, the simulation model and the experimental platform are established to verify the fault diagnosis method. The results of simulation and experiment are given to validate the proposed fault diagnosis.