Slot corona protection systems for medium voltage rotor windings subjected to PWM voltage in doubly fed induction generators

Abstract

Doubly fed induction generators using static frequency converters provide the possibility to have adjustable speed pump storage units where the active power can be controlled quickly for both generation (energy discharge) and pumping (energy storage) operation. However, high magnitude voltage spikes with high repetition rate and fast rise times (associated with PWM voltage of the converter) applied to the rotor winding, have adverse effects on the rotor insulation system. In this study using IEC 60034-18-42 test requirements, four different slot corona protection systems were evaluated. The results show that the design and manufacturing of the insulation system have great impacts on the performance of the slot corona protection system subjected to PWM voltages.

Modeling and Simulation of Rotating Machine Windings Fed by High-Power Frequency Converters for Insulation Design

“…The tangential component of the electric field in the CAT is well below the tangential electric fieldint heSGT (Figure 17(a)), but the heat generated in this coating is considerably higher (Figure 17(b)). Experimental work on form-wound coils stressed by fast pulses has shown that this condition can damage the CAT, allowing surface PD to appear right at the slot exit [51,52]. The next section introduces the use of FEM modeling to investigate possible solutionstothisproblem.…”