A novel control strategy for solar-wind hybrid energy systems based on optimal battery charge and discharge limits in various time domain

Optimal operation of hybrid energy systems has been motivated in developed countries, by decreasing operation costs and pollutions, and increasing use of renewable energy resources. This paper presents a new energy management scheme for utilization of batteries and diesel generators, to decrease operation costs and pollutions, while increase reliability simultaneously. The capacity of the system components is firstly optimized by HOMER software. Then, diesel generator capacity is optimized by particle swarm optimization (PSO) algorithm, taking into account the environmental and outage costs. In the proposed control strategy, due to the variation of power generation and power consumption in hybrid systems, different charge / discharge limits are applied for each hour of the day, instead of conventional fixed upper and lower bands for the state of charge (SOC) of battery. The results show the effectiveness of the proposed strategy on reducing the cost of power generation, the reliability and the environmental issues.