Analysis of Droop Control of BESS for VPP based Frequency Control in Distribution Network

In this paper, we analysed conventional droop control of battery energy storage systems (BESSs) installed in the distribution network to provide frequency support under a virtual power plant (VPP) type control architecture. In particular, VPP based frequency control and its subsequent impact on the network voltages depending on the X/R ratio of the network is analysed. The adverse effect on the system frequency when regulating the voltages of the network is also investigated. Frequency response based on the initial operation status of the BESSs, the sensitivity of droop coefficient in system frequency and network voltages, and the effect of voltage events on the system frequency are investigated through simulation studies conducted in DIgSILENT PowerFactory. The results show that direct use of droop controlled BESSs for frequency support in the VPP control structure can result in voltage fluctuations in the network and vice versa.