Instability risk analysis of distributed renewable energy caused by energy storage balance zone

Abstract

An energy storage balance zone (ESBZ) is formed by multiple energy storages to suppress fluctuations in distributed renewable energy (DRE). However, the effects of an ESBZ on the dynamic stability of DRE have usually been ignored, resulting in the underestimation of the potential instability risk. In this study, the impact of dynamics of an ESBZ on the small signal stability of DRE under different steady states was analyzed, and the dynamic instability risk clarified. First, a linearized interconnection model of the ESBZ and DRE was established in d-q coordinates, so that the model can be transformed into a single-input and single-output model. Based on this model, the virtual-damping method was used to analyze the influence of the ESBZ on stability of the DRE. It was found that the effects of the ESBZ vary at different steady states. The different power flows of DRE and ESBZ have different effects on DRE stability. Moreover, the increasing number of ESBZs can amplify the effects on the DRE, in the worst case, leading to instability of the DRE. Therefore, a method was proposed to determine the scale of the ESBZ considering the critical stability of the DRE. Finally, in this paper, a distribution-network system with ESBZ and DRE is selected as an example to demonstrate the correctness of the conclusions.

Keywords

• Distributed renewable energy
• Energy storage balance zone
• Instability risk
• Small signal stability