Comparing a Novel Optimal Coordinated Voltage Control and Secondary Voltage Control

This paper deals with the comparison between an optimal coordinated voltage control (OCVC) and secondary voltage control (SVC) for long-term voltage stability enhancement. OCVC model in this paper is based on quasi-steady-state (QSS) approximation, including continuous and discrete time differential-algebraic equations (DAEs). This model considers long-term voltage stability and costs of controls synthetically, which can coordinate different kinds of controls distributed over different locations. Pontryagin maximum value principle and Radau collocation method are applied to solve the OCVC model. Besides, in order to consider discrete characteristics of transformer tap control, capacitor switching and load shedding, a quadratic penalty function mechanism is incorporated to this control model. SVC model used here is a simplified version of Italian type, which is simulated by PSAT (Power system analysis toolbox). With the simulation results on New England 39 buses system, we can see that OCVC has better voltage profile, better use of reactive power resources and better capability of maintaining long-term voltage stability after disturbances.