Research on PD detection method under induced impulse voltage for stator winding of wind turbine generator

Abstract

This research mainly focuses on the PD detection for stator winding under induced impulse voltage in order to diagnose the insulation defects, especially in inter-turn insulation. The PD test result may help evaluate the integrity and quality of insulation in a form-wound stator winding of wind turbine generator (WTG). In previous work, a test system which consists of impulse voltage generator, auxiliary magnetic core and exciting coil, and high frequency current sensor has been established and applied in inter-turn PD detection for single coil. The situation gets complicated in a winding compare to the impulse induction in a single coil. In this research, a series of impulse induction tests in a real stator winding were accomplished. Impulse voltage distributions along the winding was measured and recorded when impulse voltage was induced at certain coil (target coil). Then impulse induction with two induction units in series at two adjacent target coils was studied and summarized. Four character parameters were put forward to help evaluate whether the impulse distribution is suitable for the purpose of PD detection. High frequency current sensor is applied to detect the PD related signals in the inter-turn insulation.