Long-Term Unit Commitment with Combined-Cycle Units

The performance of long-term power system studies are vital to evaluate the system reliability and efficiency under an increasing penetration of renewable energy sources (RES). This work develops a long-term unit commitment (UC) model considering combined-cycle (CC) units to enable the performance of annual studies in power systems. Specifically, a simplified configuration-based model of the CC units is used that decreases the number of configurations to reduce the computational complexity. The considered UC problem is formulated as a mixed-integer linear program (MILP), which is intractable when a long-term horizon is used. To make the problem tractable, a rolling horizon approach is proposed to solve the long-term MILP problem, generating high-quality approximate solutions. The proposed approach is applied to a real isolated power system and an annual study is carried out to examine the impact of an increasing RES penetration on the system operation

Optimal Energy Management and Scheduling of a Microgrid in Grid-Connected and Islanded Modes

Microgrids are becoming one of the main components of future smart grids. Ensuring their optimal and stable operation is of crucial importance and can be a challenging task. In this paper, two optimization algorithms are implemented for scheduling the microgrid operation in grid-connected and islanded modes, according to the priorities and objectives in each mode. For achieving an optimal operation at each mode, the proposed scheme is able to shed loads, define the generation level of the photovoltaics and regulate the charging/discharging level of the Energy Storage System (ESS). The effectiveness of the proposed scheduling is demonstrated through an analytical real-time simulation, where various transitions between the grid-connected and islanded modes are considered. The results indicate that the proposed scheme is able to regulate successfully the energy flows of the microgrid even under various transitions