Uninterrupted Supply and Frequency Support for Local Load in Microgrid by Battery Energy Storage System (BESS)

Abstract

Renewable energy is the most economic solution for new grid-connected capacity in areas with good resources. The RES power variation and their unpredictable nature may decrease the grids reliability. In this regard, this paper presents an enhanced control method for battery energy storage systems (BESS) to support the frequency of MG and with the ability of disconnecting from the MG to supplying in the island mode a local consumer. The combination of Battery Energy Storage Systems (BESS) with a hierarchical control of the resources provides a solution to overcome the frequency control issues within an MG. Within the BESS, a power electronics converter interfaces the energy storage unit with a single or three-phase MG. The power converters operation in two states, namely MG-tied or islanded, is an important feature to improve the MG flexibility and feasibility. The BESS may also provide voltage support in the point of common coupling with the MG. The proposed BESS may compensate the power absorbed by the local loads in order to improve the MG frequency response. When the MG power quality worsens under a certain stage, in terms of voltage and frequency, the BESS detaches from the MG and continues to operate islanded. The reconnection is accomplished a smoothly resynchronization of the local voltage with the MG, without troubling the local loads supply. In this proposed method, by proper maintenance of charging and discharging of battery, it enhances the lifetime of battery and it also provides the uninterrupted supply of load.