Control Instability Index (CII) based approach for evaluating weak grid integration of wind generation clusters

Significant research has been performed to evaluate the challenges and mitigation options associated with integration of individual Wind Generation Resources (WGRs) to weaker portions of the electric grid. This paper focusses on the development of a screening approach to assess control instability issues on a weak portion of grid expected to have a cluster of wind farms connected to it. A Control Instability Index (CII) based approach is introduced in the paper. The CII approach utilizes a system strength matrix of the weak portion of the network in conjunction with net gains of the voltage control loops for the wind farms to assess potential for control instability. The performance of the mathematical premise of CII based approach has been evaluated on the ERCOT transmission grid. Thresholds associated with CII levels have been established to assist system operators and planners to screen for potential instability conditions. The proposed approach provides a unique approach to address wind farm cluster integration on weak grids.