Comparison of Retrofitting Techniques for Improving LVRT Capability of Variable Speed Wind Turbine Employing SCIG
Rapid infiltration of wind farms into central power grid has prompted authorities to insist on low voltage ride through capability (LVRT) of wind turbines to prevent cascading failures. A large number of existing wind farms still employ squirrel cage induction generators (SCIG) because of their robustness and low cost. Their main drawback is absence of LVRT capability. This paper proposes enhancing the LVRT of a variable speed wind turbine(VSWT) employing squirrel cage induction generators by three techniques, braking chopper, energy storage and STATCOM.The transient behaviour of the VSWT using retrofitting devices is analyzed and simulated in MATLAB/Simulink. The losses occurring due to lack of LVRT capability was studied by collecting data from a wind farm in India employing variable speed SCIG. A comparison of technical performance and economic feasibility of the above three techniques was also done.