Denizar Cruz Martins

Federal University of Santa Catarina



Development of Microgrids in Brazil



Brazil has an average solar radiation on the order of 5400 Wh/m2 day. The region with the lowest solar radiation is located in the south of the country (Santa Catarina), whose value is around 4500 Wh/m2 day, and the region with the highest radiation is located in the northeastern region of Brazil (Piaui, Paraiba, Bahia and Minas Gerais), and its value is 6300 Wh/m2 day. With regard to wind energy, Brazil has a potential around 140 GW, with an average annual wind speed of 6.25 m/s (to 50 m of ground height), whose variation is between a maximum of 9.0 m/s and minimum of 3.5 m/s. The region with the largest wind supply is in the northeast with 75 GW, and the lowest in the central-west region with 3.1 GW. Brazil still has a great potential of energies generated from the oceans, still very little explored. It is estimated that the 8 thousand kilometers of coastal extension in Brazil can receive enough wave power plants to generate 87 GW.

From these data it is evident that Brazil is one of the most promising countries for the use of renewable energy in its industrial, commercial and residential areas. In this way, the implantation of intelligent electric grids and, above all, microgrids represent one of the main alternatives of diversification of the Brazilian energy matrix. There is a great incentive in the country for the use and application of renewable energies in all sectors of daily life, including transportation and electricity.

As far as electricity is concerned, studies are being carried out to make feasible the implantation of electrical microgrids throughout the national territory. Research is being developed to design microgrids that use renewable energies, the most being considered are: solar photovoltaic energies, wind energy and ocean energies.

Therefore, in this mini-tutorial (or Keynote) we intend to discuss the latest advances presented in Brazil regarding the development of microgrids. It will show some successful experiences involving sectors of the Brazilian Electric Power Network. Techniques employing the modified droop feature to enable the state of charge balancing of a multiple battery system in a hybrid microgrid, combining wind and PV solar energy, are described. This balancing is realized without the use of logical communication between the different converters that form the microgrid. Thus, it is possible to distribute the converters through the microgrids, helping to improve the quality of the energy supplied to the loads. Preliminary results of a microgrid consisting of a photovoltaic solar array, a set of wind turbines and a diesel generator, are presented, whose main focuses are: the description of the system, the mode of operation, and the design of the converters.

Studies of a microgrid employing oceanic energies, more specifically tidal energy, will also be presented. In this case the focus will be on the economic operation of an energy storage system, whose main source of energy comes from tidal currents. From a batteries energy storage system, a strategy is proposed here to minimize the costs with the purchase of energy from the utility. The idea is to use the energy stored in the batteries during the high energy costs of the utility.



Denizar Cruz Martins was born in São Paulo, Brazil, in 1955. He holds Electrical Engineering degree (1978), and Master's degree in Electrical Engineering (1981), all at the Federal University of Santa Catarina (UFSC) and PhD degree in Electrical Engineering from the National Polytechnic Institute of Toulouse, Toulouse, France (1986). He has published over 300 (three hundred) scientific papers. He has developed several technological projects in partnership with Brazilian Companies, resulting in the realization of some patents of invention. He is the author of four national books in the area of Power Electronics and two chapters of international books in the area of Electronic Processing of the Photovoltaic Solar Energy. He is a Founding Partner of SOBRAEP (Brazilian Power Electronics Society), having been its President for two years. He was Coordinator of the Post-Graduation Program in Electrical Engineering at UFSC. He was Head of the Electrical and Electronic Engineering Department at UFSC for two consecutive terms, and He is currently Supervisor of INEP (Power Electronics Institute). He is a full professor in the Electrical and Electronic Engineering Department at the Federal University of Santa Catarina, where He teaches undergraduate and postgraduate courses. He is accredited by the Post-Graduate Program in Electrical Engineering of UFSC for guiding students in master and in doctoral thesis. He is representative of the Power Electronics area in the Post-Graduation Program in Electrical Engineering at UFSC. He has experience in Electrical Engineering, with emphasis on Power Electronics, working mainly on the following topics: DC-DC and DC-AC static converters, power factor correction, power quality, electronic power processing, distributed generation systems, DC and AC microgrids, simulation of static converters and electric drive.