Artificial Intelligence based Battery Power Management for Solar PV And Wind Hybrid Power System

This paper proposes an approach for the hybrid solar photovoltaic and wind power system in Battery management for stand-alone applications with Artificial Intelligence. In general, Solar and wind energy are utilized as leading sources of energy and battery unit is considered as storage element to meet out the load demand. Loads are considered based on the priority. Ratings of hybrid energy system components such as solar PV, wind generator, battery unit, power electronic converter, etc., are optimally selected based on the rating of load. Fuzzy logic and Neural network are the tools being used here to obtain the maximum utilization of battery. A simulation model with MATLAB/Simulink for the hybrid power system has been developed. Considering power supply variation in Solar and Wind Hybrid Power system (SWHP) caused due to disturbed power supply from wind turbine generator and solar cells, fuzzy-PID-NN control is brought into it. The main components model of SWHP is established and simulation of fuzzyPID-NN control is being presented, analyzed and compared. The final result of simulation indicates an effective utilization of battery. Keywordsfuzzy logic; neural network; solar photovoltaic; wind power; battery management INTRODUCTION Many Countries count on coal, oil and natural gas to supply most of their energy needs due to tremendous increase in population growth rate. But reliance on fossil fuels presents a big problem. Fossil fuels are a finite resource. Eventually, the world will run out of fossil fuels, or it will become too expensive to retrieve those that remain. Fossil fuels also cause air, water and soil pollution, and produce greenhouse gases that contribute to global warming. Renewable energy resources, such as wind, solar and hydropower, offer clean alternatives to fossil fuels. They produce little or no pollution and they will never run out. SWHP has a bright application to face electric demand in the near future. It can raise power supply reliability and reduce the system cost according to local environment condition and load characteristics of residents [1]. For stand-alone SWHP, lead-acid batteries play a vital role as an energy storage unit. Even though batteries are the weaker section in the overall system, they are in need of certain initial investment of equipment. As the management of charging/discharging in storage battery directly affects the quality of power supply in SWHP since electric energy from wind turbine generator and solar cells has obvious fluctuation. It makes the system great demand to electric power management. Therefore, it is significant to study power management of batteries in detail [2]. Conventional control theories do not have good performance for them. In this paper, the combination of fuzzy control and traditional PID control is presented along with Neural Network to solve the problem of battery management in Solar and Wind Hybrid Power system. And simulation result of the fuzzy and NN control system is compared at the end [3]. Fig. 1. Block Diagram of SWHP International Journal of Engineering Research and General Science Volume 1, Issue 2, December 2013 ISSN 2091-2730 www.ijergs.org SYSTEM DESCRIPTION The SWHP is made up of solar photovoltaic array, wind turbine generator, controller with the combination of PID/fuzzy/Neural Network, storage batteries, Rectifier, chopper, inverter, etc. as shown in Fig. 1. Rectifier used in wind Turbine line is to convert AC into DC. Chopper used in Solar PV line is to convert variable DC into constant DC. Then it is connected to batteries through charge controller. Here battery will ensure reliability of the power system for all climatic conditions. Batteries will charge when the power generation from wind and solar PV system is in excess and it will discharge when the power generation from wind and solar PV is not enough to meet the load demand. Further battery makes the voltage of power supply steady. Fuzzy intelligence and NN controller are used to switch and regulate working state of batteries, so as to operate alternately in the state of charging or discharging. Thus the stability and continuity of power supply is improved. For the AC loads, PWM inverter is used to convert DC from battery into AC. SYSTEM MODEL A. Wind turbine generator model According to aerodynamics principle, output power characteristic of wind turbine is described as follows [1,2] considering the main components of a wind turbine for modeling purposes consist of the turbine rotor, a shaft and gearbox unit, an electric generator, and a control system. 2 3 ) , ( 2 1 R v C P p i     (1) Where CP is a constant denotes wind power utilization coefficient, ρ is the density of air, v is the wind speed and R is the radius of wind turbine blades. The tip speed ratio of wind turbine is written as: v R   (2) Where ω is the wind turbine angular speed and the aerodynamic torque can be expressed as: 3 2 ) , ( 2 1 R v C T T a     (3) Where ) , (   T C is the torque coefficient which is given by ) , ( 1 ) , (      P T C C  (4) The fitting functions of ) , (   P C is obtained by:       6 4 3 2 1 5 ) ( ) , ( C e C C C C C i C