Research on Inter-Turn Short-Circuit Fault Detection and Diagnosis for Dry-Type Air-Core Reactors Based on Impulse Oscillation Method

Inter-turn insulation defects in air-core reactors are a leading cause of equipment failure and pose significant threats to the safety and stability of power systems. Existing detection systems based on the pulse oscillation method typically rely on voltage regulators to raise the test voltage at power frequency, resulting in large and cumbersome equipment that limits applicability in field testing. To address this challenge, this paper proposes a high-frequency, compact high-voltage power module tailored for inter-turn insulation testing. The system employs an IGBT-based single-phase inverter and a power electronic transformer as high-frequency components, integrated with advanced voltage regulation technology. A voltage-doubling rectifier circuit is used to achieve a 12 kV DC output. The overall setup is lightweight and supports real-time voltage control via command signals, ensuring both operational safety and adaptability during testing. To evaluate the feasibility of the system, a simulation model for inter-turn insulation faults was developed. Simulation results show that when a short circuit occurs, the oscillation frequency and damping factor both increase significantly, with the waveform exhibiting accelerated attenuation-providing effective indicators for fault identification. The developed system was subsequently applied in a practical test on an air-core reactor. A total of 3000 pulse oscillation tests were completed within one minute, successfully reaching the required voltage level. The proposed device enables rapid and accurate detection of inter-turn faults, fulfilling the requirements of field applications and significantly improving both the efficiency and safety of fault diagnostics in air-core reactors.