A chance-constrained energy management in multi-microgrid systems considering degradation cost of energy storage elements

Abstract

Energy storage devices are very popular in systems with the presence of renewable-based power generation. However, inappropriate usage of them may lead to aging and also the early failure of such systems. The factors affecting the aging of the batteries as the main energy storage devices in electrical systems are frequent changes in charging and discharging status, deep discharge, and a large number of power transactions in a short time. Furthermore, the development of microgrids (MGs) in distribution networks (DNs), leads to more complicated structures known as multi-microgrid (MMG) systems. In this paper, the day-ahead scheduling for the MMG system considering the degradation cost of the energy storage systems has been proposed. To model the uncertainties, chance-constrained programming (CCP) approach has been employed. The CCP helps the system operator to make better decisions without jeopardizing the system security. The degradation cost has been designed in a way that in the energy management process, misuse of the batteries is avoided. A hierarchical three-stage energy management process is designed. First, deterministic equivalents for the CCP problem are made and using these equivalents, in the first stage, MGs perform local scheduling and in the second stage, again considering deterministic equivalents of the CCP, DN performs global management and finally, MGs perform a rescheduling. Simulations with four case studies on a modified version of the IEEE 33-bus test system have shown the effectiveness of the proposed scheduling framework. The results show that decreasing confidence level in CCP decreases the system operational costs, however, threatens the system stability. Also, considering the battery degradation cost prevents the system operator from misapplication of the battery energy storage systems.