A series dynamic resistor based converter protection scheme for doubly-fed induction generator during various fault conditions

This paper proposes a new converter protection method, primarily based on a series dynamic resistor (SDR), that avoids the doubly-fed induction generator (DFIG) control being disabled by crowbar protection during fault conditions. A combined converter protection scheme based on the proposed series dynamic resistor and conventional crowbar is analysed and discussed. The main protection advantages are due to the series topology when compared with crowbar and DC-chopper protection. Various fault over-current conditions (both symmetrical and asymmetrical) are analysed and used to design the protection in detail, including the switching strategy and coordination with crowbar, and resistance value calculations. PSCAD/EMTDC simulation results show that the proposed method is advantageous for fault over-current protection, especially for asymmetrical faults, in which the traditional crowbar protection may malfunction.