A Hybrid Approach for Coordinated Voltage Stability Control using amalgamation of Fuzzy and Taguchi Method

On-load tap changers (OLTCs) play a vital role in maintaining power system stability and quality by adjusting bus voltages to desired levels during disturbances. However, while OLTCs are beneficial in achieving voltage control under normal conditions, their operation may increase the risk of voltage collapse in heavily loaded scenarios, making their impact on system stability both advantageous and potentially adverse. This study introduces a two-stage coordinated approach to ensure optimal power quality under diverse loading conditions. In the first stage, a novel index is used to identify heavily loaded, critical transformers to locate OLTCs most susceptible to instability. Voltage stability issues are then addressed through coordinated control of OLTCs and dynamic VAR compensators, optimized using the Taguchi method (TM). In the second stage, a fuzzy multi-objective optimization problem is formulated to refine OLTC tap settings and optimize the operating points of dynamic VAR controllers for enhancing system stability and reducing power loss. The proposed approach is validated on the IEEE 30-bus test system, showing significant improvement in power quality and stability across loading conditions. Results underscore the effectiveness of this coordinated strategy, offering valuable insights for future power system planning and operation.