Renewable and Sustainable Energy Reviews 16 (2012) 1577–1587 Contents lists available at SciVerse ScienceDirect Renewable and Sustainable Energy Reviews j ourna l h o mepage: www.elsevier.com/locate/rser A comprehensive method for optimal power management and design of hybrid RES-based autonomous energy systems S. Abedi a , A. Alimardani b,∗ , G.B. Gharehpetian b , G.H. Riahy a , S.H. Hosseinian b a Renewable Energy Lab, National Center of Excellence in Power Engineering, Department of Electrical Engineering, Amirkabir University of Technology (Tehran Polytechnic), P.O. Box: 15875-4413, 424 Hafez Ave., Tehran, Iran b National Center of Excellence in Power Engineering, Department of Electrical Engineering, Amirkabir University of Technology (Tehran Polytechnic), P.O. Box: 15875-4413, 424 Hafez Ave., Tehran, Iran a r t i c l e i n f o Article history: Received 22 May 2011 Accepted 25 November 2011 Available online 18 January 2012 Keywords: Hybrid energy systems Optimum power management strategy Differential evolution algorithm Fuzzy multi-objective optimization Resource uncertainty a b s t r a c t The power management strategy (PMS) plays an important role in the optimum design and efficient utilization of hybrid energy systems. The power available from hybrid systems and the overall lifetime of system components are highly affected by PMS. This paper presents a novel method for the determina- tion of the optimum PMS of hybrid energy systems including various generators and storage units. The PMS optimization is integrated with the sizing procedure of the hybrid system. The method is tested on a system with several widely used generators in off-grid systems, including wind turbines, PV panels, fuel cells, electrolyzers, hydrogen tanks, batteries, and diesel generators. The aim of the optimization problem is to simultaneously minimize the overall cost of the system, unmet load, and fuel emission considering the uncertainties associated with renewable energy sources (RES). These uncertainties are modeled by using various possible scenarios for wind speed and solar irradiation based on Weibull and Beta proba- bility distribution functions (PDF), respectively. The differential evolution algorithm (DEA) accompanied with fuzzy technique is used to handle the mixed-integer nonlinear multi-objective optimization prob- lem. The optimum solution, including design parameters of system components and the monthly PMS parameters adapting climatic changes during a year, are obtained. Considering operating limitations of system devices, the parameters characterize the priority and share of each storage component for serving the deficit energy or storing surplus energy both resulted from the mismatch of power between load and generation. In order to have efficient power exploitation from RES, the optimum monthly tilt angles of PV panels and the optimum tower height for wind turbines are calculated. Numerical results are com- pared with the results of optimal sizing assuming pre-defined PMS without using the proposed power management optimization method. The comparative results present the efficacy and capability of the proposed method for hybrid energy systems. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Distributed generation (DG) has been recently nominated as one of the solutions to reliable, less costly, and more efficient energy supply systems. Specifically, small DG systems with power level ranging from 1 kW to 10 MW [1], located near the loads, are extensively utilized both in grid-connected and stand-alone modes. Among available DGs, renewable-based systems (RES) such as photovoltaics and wind turbines have attained the most popularity due to ever increasing concerns about depletion of fossil fuels and global warming. They have also been getting more cost-effective during recent years. However, a significant drawback associated with solar and wind energy systems is their intermittent and unpredictable behavior ∗ Corresponding author. E-mail address: arash.alimardani@ieee.org (A. Alimardani). due to their direct dependence on climatic conditions. In addition, the variations of the wind and solar energy may not match with load changes [2]. The reliability of the system is important to both plan- ning and utilization stages. Designing energy systems including solar and wind energies together, to some extent, reduces the depth of the problem. Since, the advantage of one source can overcome the disadvantage of the other one and vice versa [3]. In addition, taking into account the intermittency and uncertainty associated with solar and wind energy sources, improves the adaptation of design results with practical and realistic conditions. Another con- ventional solution is appropriate incorporation of energy storage devices such as batteries and hydrogen storage systems compris- ing electrolyzers, hydrogen tanks and fuel cells into the system [3]. Hence, hybrid energy systems are becoming more attractive to power engineers. One of the most prominent issues regarding hybrid energy systems is to determine their optimum design and operation modes taking account of regional conditions and load demand 1364-0321/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.rser.2011.11.030