Oscillation Identification and Frequency Damping Controller Design for Battery Energy Storage System Using Subspace Identification

In this paper, a novel method for the identification of oscillatory modes based on subspace identification is proposed for bulk electric grids integrated with renewable energy resources (RERs) and battery energy storage systems (BESS). The main contribution of the work is the development of a subspace identification framework to monitor the grid at various measurement points and identify the oscillatory modes. Based on this information, the paper also proposes a control algorithm for BESS that can damp the frequency oscillations of the grid. The main advantage of such a technique is its ability to improve electric grid stability with millions of RERs and BESS. The architecture is tested on a smaller electric grid model and modified IEEE test system models. It was found that the proposed method not only provides information regarding the system oscillatory modes in grid-connected and islanded modes of operation with RERs and BESS, but it is also capable of damping frequency oscillations. As showcased in validation, the improvement in frequency oscillation damping is more than 20%.