Copyright © 2018 N K Rayaguru et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Engineering & Technology, 7 (1.2) (2018) 47-52 International Journal of Engineering & Technology Website: www.sciencepubco.com/index.php/IJET Research paper Mathematical modeling and control of wind energy electric conversion system feeding standalone load N K Rayaguru 1 *, N. Poornachandra Rao 2 , K. Navin Sam 3 , Sunil Kumar Thakur 3 1 Associate Professor, Veltech Multitech Dr.Rangarajan Dr. Sakunthala Engg.College,Chennai 2 2Assistant professor, Veltech Dr.RR & SR University, Chennai 3 Assistant professor, National Institute of Technology, Puducherry 4 PG Student, Veltech Dr.RR & SR University, Chennai *Corresponding author E-mail: kumarrayaguru@veltechmultitech.org Abstract In this paper, state space model of the complete Wind Energy Electric Conversion System (WEECS) comprising of wind turbine, Perma- nent Magnet Synchronous Generator (PMSG), uncontrolled rectifier, DC-DC boost converter, and SPWM inverter feeding a standalone load has been formulated. The derived state space model is then simulated using Matlab/Simulink to test the model. As the standalone three phase load connected to the inverter demands constant output voltage irrespective of intermittent wind pattern, a PI controller is used to control the duty ratio of DC-DC boost converter to maintain constant output voltage at the inverter end. Keywords: WEECS; PMSG; Boost Converter. 1. Introduction In India, electricity supply and demand gap is widening over the years because of increasing load and lack of generation expansion [1]. Hence, to reduce the supply and demand gap, government is planning to expand generation capacity. In view of the rising tem- perature of the earth due to global warming, generating stations utilizing renewable energy as primary resource are becoming pop- ular [2]. In addition, as most of the people lives in remote areas, the extension of existing transmission network to such areas is economically unviable. So Renewable Electric Energy Conversion Systems (REECS) are becoming popular alternatives to cater the power supply needs of people living in remote areas. Various authors have developed stand-alone REECS using variety of re- newable sources to supply isolated loads. In this context, WEECS is found to be one of the good candidates for the stand-alone gen- erating stations. Most of the literature available utilizes induction machine (or) permanent magnet synchronous machine (PMSG) for electricity generation in such WEECS [3]. The merits and demerits of both these electromechanical conversion systems have been detailed in [4]. On one hand, the use of induction machine based WEECS is not suitable for isolated loads. Also it requires an additional capacitor bank which consumes magnetizing reactive power rather than delivering it. In addition, the control of IM based systems is com- paratively complex than PMSG based systems. On the other hand PMSG based systems does not require any capacitor bank and also it is easy to control. So, in general IM based systems are preferred for high power capacity grid connected operation and PMSG based systems are preferred for low power capacity isolated opera- tion. In this paper, a 650W wind generator is used to supply iso- lated load and hence PMSG is chosen. The objective of this paper is to derive a state space model of PMSG driven WEECS feeding standalone load and test the de- rived model using Matlab. In order to maintain constant voltage across the inverter end irrespective of wind speed variation, a closed loop PI controller is used to control the duty ratio of DC- DC boost converter. This complete system is simulated using the system dynamic equations. 2. System configuration Fig.1 shows the complete system configuration of a typical PMSG based WEECS feeding an isolated load. The different components of the system are given below: • Wind turbine • Permanent magnet synchronous generator (PMSG) • Uncontrolled rectifier • DC-DC boost converter • Three phase voltage source inverter (VSI) • Three phase load Fig. 1: Configuration of PMSG Based WEECS Feeding Isolated Load. Wind turbine connected to PMSG generates fluctuating voltage pertaining to intermittent wind pattern. The obtained voltage is