Microgrid wireless energy management with energy storage system

Abstract

The penetration of renewable energy sources in small-scale power production gives the opportunity parts of the grid to work as microgrids. The microgrid should be able to work both in grid-connected and island mode, while its voltage and frequency deviations follow the EN 50160 standard. The use of energy storage system is generally recommended in order to absorb the mismatches between the demand and the generation side and to preserve the quality of the microgrid voltage. While the up to day research is mainly concentrated on energy management based on communication, this paper proposes a wireless method for keeping the voltage and the frequency within the limits, using a battery as an energy storage system (ESS). An analytical expression for calculating the battery capacity is also proposed. The active and reactive power sharing among the parallel resources is achieved using the droop control method and an algorithm proportional to droop characteristic and the rated apparent power of each resource. According to the values of frequency and voltage and the State of Charge (SoC), the battery is connected in the microgrid, working in charging or discharging mode. A microgrid consisting of two inverter-interfaced power resources, a battery and a constant power load is investigated. Simulation results demonstrate that the proposed wireless control method provides the load with a high quality voltage in both grid-connected and islanded mode under several load scenarios.