Multistage Preventive Scheme for Improving Voltage Stability and Security in an Integrated Renewable Energy System

Abstract

The trend of renewable energy integration, power system size and complexity growth, occurrence of line contingencies, and more stressed loading conditions for power systems increase the threat of voltage stability, which has recently been among the main problems in power systems. This paper proposes a multistage preventive scheme based on voltage stability and security monitoring and control. A stochastic security-constrained optimal power flow considering voltage stability and renewable energy generation uncertainty, reactive power compensator tap re-operation minimization, and load-shedding minimization problems are hierarchically implemented in the proposed method. This method ensures voltage stability under the uncertainty of renewable energy generation and selected line contingencies considering their occurrence probability and/or voltage instability severity level for the upcoming time-slot. Several cases based on a modified IEEE 57-bus test system are used to demonstrate the effectiveness of the proposed method. The simulation results show that the proposed method can make an important contribution to improve voltage stability and security performance under severe conditions, especially to handle the uncertainty.