Optimal Cost of Voltage Security Control Using Voltage Dependent Load Models in Presence of Demand Response

This paper proposes a new framework for corrective voltage control (CVC) of power systems. It ensures a desired loading margin (LM) after encountering severe contingencies while minimizing the corresponding control costs. The framework is divided into primary CVC (PCVC) and secondary CVC (SCVC) stages for restoration of voltage stability and ensuring a desired LM. These stages are based on the sequence and quickness of the control actions required in post-contingency state of the system. The PCVC sub problem deals with the condition faced by a power system subject to voltage instability as the result of severe contingencies. Such control is merely devised to restore system stability. Next, in the SCVC sub problem that follows PCVC, the system operating point is modified such that a desired LM is ensured, and hence voltage security of the system is achieved. The active and reactive power redispatch of generation units and involuntary load curtailment are employed along with the voluntary demand-side participations as control facilities in PCVC and SCVC sub problems, by deploying a proper voltage dependent static model for loads. The proposed framework is examined on the IEEE 118-bus system. The numerical results substantiate the effectiveness of the proposed approach.