International Electrical Engineering Journal (IEEJ) Vol. 5 (2014) No.4, pp. 1305-1312 ISSN 2078-2365 http://www.ieejournal.com/ 1305 Rajkumar and Suganthi Hybrid Control Scheme for Fault Ride-Through Capability using Line-Side Converter and an Energy Storage System for PMSG Wind Turbine Systems A Hybrid Control Scheme for Fault Ride-Through Capability using Line-Side Converter and an Energy Storage System for PMSG Wind Turbine Systems S.Rajkumar 1 , S.T.Suganthi 2 1 Department of EEE,SNS College of Technology, Coimbatore-35 2 Department of EEE,SNS College of Technology,Coimbatore-35 1 rajkumareee89@gmail.com, 2 suganthi.sb@gmail.com Abstract — As the wind power installations are increasing in number, Wind Turbine Generators (WTG) are required to have Fault Ride-Through (FRT) capabilities. Lately developed grid operating codes demand the WTGs to stay connected during fault conditions, supporting the grid to recover faster back to its normal state. In this paper, the generator side converter incorporates the maximum power point tracking algorithm to extract maximum energy from wind turbine system. A hybrid control scheme for energy storage systems (ESS) and braking choppers for fault ride-through capability and a suppression of the output power fluctuation is proposed for permanent-magnet synchronous generator (PMSG) wind turbine systems. During grid faults, the dc-link voltage is controlled by the ESS instead of the line-side converter (LSC), whereas the LSC is exploited as a STATCOM to inject reactive current into the grid for assisting in the grid voltage recovery. A simple model of the proposed system is developed and simulated in MATLAB environment. The effectiveness of the system is validated through extensive simulation results Index Terms- Boost converter, Braking Chopper(BC),dc-link control, energy storage system(ESS),ride through, STATCOM, Permanent Magnet Synchronous Generator. I. INTRODUCTION The development of various wind turbine (WT) configurations in the last decade has been very dynamic and has resulted in larger ratings and higher operating speed ranges allowing them to be tied up to the grid more easily. Variable speed operation of wind energy conversion systems (WECS) make them more ‘grid-friendly’. Permanent magnet synchronous generators (PSMG) based WECS are emerging as strong competitors to the other variable speed technologies. The power converter, whose rating is the same as that of the generator, connected between PMSG and grid allows full controllability of the system during normal operation and fault conditions. Further, PMSG operates at higher efficiency and better power factor than its counterparts especially when it functions as a direct driven generator [1-3]. WECS based on PMSG can be connected to the grid by using a voltage source converter (VSC) on the grid side and by using either a diode converter with a buck-boost converter or a VSC on the machine side. Evidently, using VSC on both machine and grid sides offer full control of active and reactive powers resulting in the best performance [4-6] in terms of power output, quality of power and performance during faults. Different strategies have been presented by various authors, to enhance fault ride through (FRT) capabilities of PMSG based WECS. Many devices, such as static var compensator (SVC), dynamic voltage restorers (DVR), Static Synchronous Compensators (STATCOM) etc have been shown to improve FRT of WECS, but they will also increase the overall cost of the system [7-8]. In [9], a nonlinear controller design for power converter based WT system is presented which ensures that current levels remain within design limits, even at greatly reduced voltage levels. A back to back connected voltage source- converter (VSC) configuration is discussed in [10] where the machine side converter (MSC) controls the speed of the generator by using a flux vector control technique and the grid side converter (GSC) controls the power flow by PWM technique Transient analysis of a grid connected wind driven PMSG is presented in [11] and a comparison is presented with the other generators at fixed and variable speeds. An electromagnetic braking resistor controlled using power electronic switch is used to dissipate