Reactive power reserve management tool for voltage stability enhancement

This study introduces an efficient management approach of the effective reactive power reserves considering the trade‐off of the security level for N − 1 contingencies and economical concerns. The proposed method is deemed as an operational planning tool that simultaneously minimises the operating cost for a given forecasted load and control cost of the likely disturbances while ensuring that the level of available effective VAR reserves is adequate to withstand the credible severe contingencies without violating system security. The load shedding as a last resort control option is included in the problem formulation to guarantee that the voltage stability margins are maintained at a minimum control cost. The sensitivity of the load margin with respect to the generator VAR output is employed in order to determine the generator relative worth for keeping voltage security. Since the presented problem is a large‐scale optimisation problem consisting of a base case and several sub‐problems representing contingency states, a hybrid method based on particle swarm optimisation and conventional method is used as a solution methodology. The effectiveness of the proposed approach has been validated by its implementation on a six‐bus system and IEEE 57‐bus system.