With the development of power electronic technology, power electronic devices are widely used in power system. Power electronic devices are subjected to high-frequency, steep rising and falling edge pulsed electric fields during operation, which will lead to the insulation more prone to failure. Based on the pulsed electro-acoustic (PEA) method, the behavior of space charge at the rising and falling edges of pulsed electric field is studied. It is found that the rising and falling edges of the pulsed electric field will cause the space charge to vibrate and produce stress waves. Stress wave exists with the working of power electronic devices, and is related to its working state. Therefore, it can be used for real-time condition monitoring of power electronic devices. To explore the influencing factors of stress wave, stress wave caused by different insulation defects is studied. It is found that the stress wave signal will be distorted at the insulation defect. This phenomenon is caused by the accumulation of space charge at the defect, and the attenuation and dispersion of stress wave at the defect. Fourier decomposition of the stress wave is performed, and it is found that defects will lead to the appearance of high-frequency components. This phenomenon shows that the stress wave generated by space charge vibration can reflect the internal insulation failure of power electronic devices.

power electronic devices;space charge vibration;stress waves;insulation failure;real-time online monitoring