Risk-based preventive-corrective security constrained optimal power flow for ac/dc grid

The limitations associated with the traditional N-1 reliability criterion and increasing system operation uncertainties are key drivers for switching to risk-based criteria for secure and optimal grid operation. The increased use of HVdc technology in existing power system motivates the need for inclusion of converter control into the decision-making for reliable operation. In line with these objectives, this paper introduces a non-linear preventive-corrective security constrained optimal power flow formulation for a hybrid ac/dc system. The model is used to investigate the impact of contingency probability, corrective costs and converter corrective control on the resulting risk and trade-off between preventive and corrective actions. The analysis finds that while lower contingency probability requires only corrective actions, higher probability leads to preventive actions in addition to corrective control. The exclusion of converter corrective control leads to higher operational risk and preventive costs as compared to the case allowing the converter actions in corrective stage, thus highlighting the additional flexibility offered by converters in reliability management.