Advanced Angle Estimation using Kalman Filter for high impedance Grid-following Inverters Stability

Frequency and phase angle are important factors in maintaining stability of power systems integrated with Grid-following inverters. This has led to the development of various grid synchronisation techniques. In practice, high grid impedance presents a significant challenge to the stability of power systems. However, most existing methods neglect to consider this issue. This research proposes an Advanced Angle Estimation using Kalman Filter technique, which incorporates grid impedance terms into state space models as part of the Kalman Filter approach. This is used to estimate instantaneous phase angle and frequency using Synchronous Reference Frame equations in a-fi frame. Using the proposed approach in this paper, the stability performance of a two-source system is applied and validated, using eigenvalue analysis. The results demonstrate improved performance of this technique over the Conventional Angle Estimation using Kalman Filter and Conventional Phase-Locked Loop methods, in terms of accuracy, distortion reduction, and convergence time under conditions of increases in grid impedance due to abrupt load change, switching, etc.