Multi-Objective Combinatorial Optimization of Trigeneration Plants Based on Metaheuristics

Mirko Stojiljković,Mladen Stojiljković,Bratislav Blagojević

doi:10.3390/en7128554

Abstract

In this paper, a methodology for multi-objective optimization of trigeneration plants is presented. It is primarily applicable to the systems for buildings’ energy supply characterized by high load variations on daily, weekly and annual bases, as well as the components applicable for flexible operation. The idea is that this approach should enable high accuracy and flexibility in mathematical modeling, while remaining efficient enough. The optimization problem is structurally decomposed into two new problems. The main problem of synthesis and design optimization is combinatorial and solved with different metaheuristic methods. For each examined combination of the synthesis and design variables, when calculating the values of the objective functions, the inner, mixed integer linear programming operation optimization problem is solved with the branch-and-cut method. The applicability of the exploited metaheuristic methods is demonstrated. This approach is compared with the alternative, superstructure-based approach. The potential for combining them is also examined. The methodology is applied for multi-objective optimization of a trigeneration plant that could be used for the energy supply of a real residential settlement in Niš, Serbia. Here, two objectives are considered: annual total costs and primary energy consumption. Results are obtained in the form of a Pareto chart using the epsilon-constraint method.

Highlights

On-site energy systems with cogeneration, trigeneration and thermal storage are very important today, because of their significant potential to provide benefits related to finances, energy efficiency, environmental impact, flexibility and security of the energy supply
The proposed approach is applied for the optimization of an energy plant that might supply a residential settlement in Niš, Serbia
The analysis is performed for one typical year within the horizon of 15 years, the annual inflation rate of 8% and the neglected residual value of the equipment after the horizon observed

Summary

Introduction

On-site energy systems with cogeneration, trigeneration and thermal storage are very important today, because of their significant potential to provide benefits related to finances, energy efficiency, environmental impact, flexibility and security of the energy supply. Their main advantages are: high conversion efficiency, low losses due to relative closeness to the consumers and operational flexibility. Synthesis optimization defines the configuration, i.e., the set of components included in the system and their interconnections. Synthesis decision variables are usually binary (0–1), indicating whether a component or an interconnection should be included or not. Design optimization implies the technical specifications of the components and the properties of substances at nominal loads

Methods

Results

Conclusion