Power systems need reactive power support to withstand voltage instability issues. The Volt Ampere reactive (VAr) resources are to be optimally determined for location and size. Generally, candidate locations are determined based on the ranking of buses according to sensitivity indices, and the Trajectory Sensitivity Index (TSI) is the most widely used sensitivity index. However, the locations identified by ranking the buses at the system level using the TSI method do not guarantee an optimal VAr solution. The recent methods based on dividing the power system into zones address the issue of optimality. The prevailing zoning methods are based on the computation of the electrical distance between buses and do not address the zoning scenario where the electrical distance between the buses is indeterminable. This paper introduces a new multistage algorithm for grouping the buses into zones even when the electrical distance is indeterminable. The new proposed strategy encompasses applying proposed analytical and parametric techniques after the standard clustering steps. A new index, namely the Bilateral Sensitivity Index (BSI), is introduced to quantify the proximity of buses. The TSI-based zonal level ranking of buses is introduced. The proposed strategy demonstrates that when TSI is employed to rank the buses at the zonal level rather than at the system level, it helps towards an optimal VAr solution. The new multistage clustering strategy is integrated into the generalized Dynamic Voltage Stability Analysis (DVSA) framework for optimal VAr determination and applied to study the voltage collapse phenomenon on a practical 24-bus system in the southern part of India. The results demonstrate the proposed approach’s efficacy in mitigating voltage instability issues through optimal VAr support.

Maintaining voltage stability is an important factor in modern power system study and operation. Supplementing the system with reactive power (VAr) support devices such as FACTS helps to overcome voltage instability issues. Commonly, dynamic optimization based method is employed to study the dynamic Voltage Stability Analysis (VSA) of the system. The existing dynamic optimization approach has dependencies on the availability of specific tools and the FACTS model to perform dynamic VSA.  Besides, the application of the existing method for the voltage collapse phenomenon is not addressed in detail. It is desirable to have a generic dynamic VSA approach that does not have dependencies on specific tools and the FACTS model. This paper proposes a new generic approach to carry-out dynamic VSA with any given DAE tool. A method of emulating the FACTS device’s behaviour for dynamic VAr injection is introduced using an incremental optimization approach. A generic interface is newly developed as a Modifiable Off The Shelf (MOTS) component to couple the DAE solver and optimization solver.  The existing approach is enhanced into a generic dynamic optimization framework by integrating incremental optimization technique and the generic interface. Voltage collapse phenomenon on IEEE-9 bus system is investigated employing the enhanced framework.  Post contingency behaviour of the system illustrates the successful mitigation of voltage collapse issues. Obtained results show the effectiveness of the new generic approach in performing dynamic VSA.