DESIGN OF MPPT BASED HYBRID WIND AND FUEL-CELL ENERGY SYSTEM Ch Rambabu, M Sunil Kumar and N Sri Harish Sri Vasavi Engineering College, Tadepalligudem, W.G.Dt., A.P.-534101 ram_feb7@rediff.com Abstract The wind energy conversion system can deliver the maximum power when the load impedance matches with the source impedance under a given wind speed. Since the load and wind speed are varying dynamically, the maximum power point tracking (MPPT) becomes more complex. A wind-generator (WG) maximum-power-point tracking (MPPT) system is presented in the present work, consisting of a high efficiency buck-type dc/dc converter and a control unit running the MPPT functions. The advantages of the MPPT method are that no knowledge of the WG optimal power characteristic or measurement of the wind speed is required and the WG operates at a variable speed. Thus, the system features higher reliability, lower complexity and less mechanical stress of the WG. A hybrid algorithm is used for tracking the maximum power. In this method, on power variation, the duty cycle is adjusted in according to the variation in rectifier output voltage. Key words: Maximum Power Point Tracking (MPPT), Wind Energy Conversion System (WECS). 1. Introduction The worldwide concern about the environment has led to increasing interest in technologies for generation of renewable electrical energy. The ever-increasing demand for conventional energy sources has driven society towards the need for research and development of alternative energy sources. Many such energy sources, such as wind energy, fuel-cells and photovoltaic‟s are now well developed, cost effective and they are widely used. These sources offer the advantages of load shifting, customer demand, production of power in environmentally friendlier ways, and emergency backup power[1]-[5]. These generation systems allow utility companies to locate small energy generating or storage units closer to the customer. These sources face many hurdles, such as cost, grid interface issues, power. Today more than ever, environmental concerns have taken a prominent seat in the forefront of people's minds. The coupling of this with rapid advancements in the field of wind turbine generation has made this mode of electricity production a realistic option on the commercial scale. It has become more and more possible to produce 'green' electricity at reasonable rates, which translates into profit that may become more significant[4]-[7]. Wind energy system consists of a turbine coupled to a generator and the turbine is rotated by means of the wind energy. Most modern wind power is generated in the form of electricity by converting the rotation of turbine blades into electrical current by means of an electrical generator. Wind generators (WGs) have been widely used both in autonomous systems for supplying power to remote loads and in grid-connected applications. Although WGs have a lower installation cost compared to fuel cells, the overall system cost can be further reduced using high-efficiency power converters, controlled such that the optimal power is acquired according to the atmospheric conditions. In windmills (a much older technology) wind energy is used to turn mechanical machinery to do physical work, like crushing grain or pumping water[17]. Wind power is used in large-scale wind farms for national electrical grid as well as in small individual turbines for providing electricity to rural residences or grid-isolated locations. The countries with the highest total installed capacity are Germany (20,621 MW), Spain (11,615 MW), USA (11,603 MW), India (6,270 MW) and Denmark (3,136 MW). Maximized electricity generation by wind turbines is an interesting topic in electrical engineering and many types of variable speed generating systems have been researched to achieve this goal. Use of a variable speed generating system in wind power applications can increase the captured wind energy by 10-15% annually [17]. This can yield a significant revenue increase over a 20 or 30 years life of operation. The designers of small turbines (up to about 40 KW) stress simplicity over complexity and the machines are designed for little or no maintenance. Integrated horizontal axis wind-rotor designs, simplified to reduce the number of moving parts have emerged as the most successful general configuration. The variability and intermittent character of renewable resources requires the system to have back-up generation capability and/or energy storage, the latter usually a battery bank. A nominal battery bank voltage of 120 or 240V is common. In battery charging stations, batteries are connected in series and in parallel and the whole battery bank is charged through a wind turbine [12]-[17]. 2. Wind Energy Conversion System Wind energy is transformed into mechanical energy by means of a wind turbine that has one or several blades. The turbine is coupled to the generator Ch Rambabu et al, International Journal of Computer Science & Communication Networks,Vol 1(3), 297-304 297 ISSN:2249-5789