Abstract The single-phase insulation fault caused by high temperature, high current and heating loss in the nuclear reactor electric heating engineering environment is the main fault in IT systems. The paper analyzes two scenarios of single-phase insulation faults: ① the total injected source loop current is small when the insulation resistance of the faulty branch is large; ②the branch resistive current is small when the distributed capacitance of the faulty branch is too large. Based on the errors arising from these two scenarios, the paper summarizes the basic principle of the dual-frequency method to detect insulation resistance, and proposes a dual-frequency injection insulation monitoring method for variable frequency and voltage based on the weak signals extracted by dual-phase locking amplification technology. By building a simulation model in Matlab/Simulink, the data from several simulation tests show that the error of insulation resistance is controlled within 5% and 10% at 2~500kΩ and 500kΩ~3MΩ. The theoretical feasibility of the method is verified.
LIU Jianhui,ZENG Tiejun,WANG Xinlin. A dual-frequency injection insulation monitoring method based on frequency conversion and voltage conversion[J]. Electrical Engineering, 2022, 23(4): 18-24.
2022, Vol. 23 
