Flexible Operation of Hybrid Distributed Energy System Based on Reliability Redundancy

Abstract

This paper establishes a reliable-economic power sharing scheme of distributed energy system (DES) consists of Li-ion storage battery and photovoltaic (PV) source connected to the utility grid through a distribution feeder. The system is intended to supply a vehicle charging station that requires dense energy production for efficient and short time charging process. Therefore, the issue of battery state-of-charge (SOC) optimal scheduling and power routing among the sources are considered as a technical-economic problem from system dynamic reliability point of view. In the developed optimization framework, the required energy reserve, the optimal SOC scheduling, and the impact of the station on the utility grid are considered and investigated. A new PSO based optimization is proposed to optimize the power sharing of the sources using reliability based optimal power flow scheduling. The proposed methodology quantifies the reliability redundancy of the system to reliably dispatch the power between the sources. The reliability redundancy concept is proposed as a tool to dynamically schedule the battery SOC and updates the power dispatching among the sources in order to: (1) establish a flexible reserve margin, (2) increase the overall number of battery charging/ discharging cycles, (3) economically dispatch the power, and (4) provide an indirect grid service by decreasing the impact of the charging station on the utility grid. The results show that the system reliability is maintained and the number of accumulated cycles is increased by 134 cycles. Furthermore, the maximum imported grid power is decrease from 40.0 kW to 28.3 kW.