Energy is a vital input for social and economic development. As a result of the generalization of agricultural, industrial and domestic activities the demand for energy has increased remarkably, especially in emergent countries. This has meant rapid grower in the level of greenhouse gas emissions and the increase in fuel prices, which are the main driving forces behind efforts to utilize renewable energy sources more effectively, i.e. energy which comes from natural resources and is also naturally replenished. Despite the obvious advantages of renewable energy, it presents important drawbacks, such as the discontinuity of generation, as most renewable energy resources depend on the climate, which is why their use requires complex design, planning and control optimization methods. Fortunately, the continuous advances in computer hardware and software are allowing researchers to deal with these optimization problems using computational resources, as can be seen in the large number of optimization methods that have been applied to the renewable and sustainable energy field. This paper presents a review of the current state of the art in computational optimization methods applied to renewable and sustainable energy, offering a clear vision of the latest research advances in this field.

Optimization methods applied to renewable and sustainable energy: A review

In solving the electrical power systems economic dispatch (ED) problem, the goal is to find the optimal allocation of output power among the various generators available to serve the system load. With the continuing search for alternatives to conventional energy sources, it is necessary to include wind energy conversion system (WECS) generators in the ED problem. This paper develops a model to include the WECS in the ED problem, and in addition to the classic economic dispatch factors, factors to account for both overestimation and underestimation of available wind power are included. With the stochastic wind speed characterization based on the Weibull probability density function, the optimization problem is numerically solved for a scenario involving two conventional and two wind-powered generators. Optimal solutions are presented for various values of the input parameters, and these solutions demonstrate that the allocation of system generation capacity may be influenced by multipliers related to the risk of overestimation and to the cost of underestimation of available wind power.

An Economic Dispatch Model Incorporating Wind Power

Public awareness of the need to reduce global warming and the significant increase in the prices of conventional energy sources have encouraged many countries to provide new energy policies that promote the renewable energy applications. Such renewable energy sources like wind, solar, hydro based energies, etc. are environment friendly and have potential to be more widely used. Combining these renewable energy sources with back-up units to form a hybrid system can provide a more economic, environment friendly and reliable supply of electricity in all load demand conditions compared to single-use of such systems. One of the most important issues in this type of hybrid system is to optimally size the hybrid system components as sufficient enough to meet all load requirements with possible minimum investment and operating costs. There are many studies about the optimization and sizing of hybrid renewable energy systems since the recent popular utilization of renewable energy sources. In this concept, this paper provides a detailed analysis of such optimum sizing approaches in the literature that can make significant contributions to wider renewable energy penetration by enhancing the system applicability in terms of economy.

Optimum design of hybrid renewable energy systems: Overview of different approaches

Modeling, planning and optimal energy management of combined cooling, heating and power microgrid: A review

An update literature review on trends in optimization techniques used for the design and development of solar photovoltaic–wind based hybrid energy systems is presented. The main objective is to identify latest promising techniques for the optimization of solar photovoltaic (PV)–wind based hybrid systems. Different techniques used by researchers for the optimization of renewable based hybrid energy systems are reviewed along with PV–wind based hybrid system sizing methodology, is presented. Optimization studies during last 2.5 decades by researchers using traditional and new generation methods are analyzed and sixteen optimization methods including hybrid algorithms are presented. The trend shows that new generation artificial intelligence algorithms are mostly used during last decade as these require less computation time and have better accuracy, good convergence in comparison to traditional methods. The study suggests using hybridization of two or more algorithms to overcome the limitations of a single algorithm. Additionally some other techniques are identified for follow up research in the design of PV–wind hybrid systems. This review will be useful for researchers to face complexity and challenges in renewable energy based hybrid system research.

Review of recent trends in optimization techniques for solar photovoltaic–wind based hybrid energy systems

As wind power penetrations increase in isolated power systems, more innovative and sophisticated approaches to system operation will need to be adopted due to the intermittency and unpredictability of wind power generation. In this paper, a hybrid approach of combining branch and bound algorithm with a dynamic programming algorithm is developed to coordinate the wind and thermal generation scheduling problem for operating an isolated hybrid power system reliably and efficiently. Several technique constraints are applied to determine the maximum proportion of wind generator capacity that can be integrated into the system. A simplified dispatch based on the direct search method (DSM) is also introduced to relieve the computational burden further. Numerical experiments are included to understand the wind generator capacity in production cost analysis and to provide valuable information for both operational and planning problems.

Optimal Wind–Thermal Generating Unit Commitment

Optimal wind-thermal coordination dispatch in isolated power systems with large integration of wind capacity

The rise of environmental protection and the progressive exhaustion of traditional fossil energy sources have increased the interests in integrating wind energy sources into existing power systems. Development of better wind-thermal coordination algorithms is necessary to determine the optimal proportion of wind generator capacity that can be integrated into the system for operating an isolated hybrid power system reliably and efficiently. A stochastic searching technique, which utilises a simulated annealing (SA) approach combined with an efficient constrained dynamic economic dispatch (CDED) method, is developed to coordinate the wind and thermal generation scheduling in isolated power systems with large integration of wind capacity. The SA algorithm is used for the scheduling of the generating units, whereas a direct search method routine carries out the ramp rate CDED when considering wind power generation. Several technique constraints are applied to determine the maximum proportion of wind generator capacity that can be integrated into the system. A constraint satisfaction technique for generating feasible neighbouring solution is also developed to improve the SA solution process. Numerical experiments are included to understand the wind generator capacity in the operating cost analysis and to provide valuable information for both the operational and planning problems.

Chun-Lung Chen

Papers

Optimal Wind–Thermal Generating Unit Commitment

Optimal wind-thermal coordination dispatch in isolated power systems with large integration of wind capacity

Simulated annealing-based optimal wind-thermal coordination scheduling

Unit commitment with probabilistic reserve: An IPSO approach

Non-convex economic dispatch: A direct search approach