Voltage instability performance of risk-based security constrained optimal power flow

•The RB-SCOPF can be solved using a two-layer decomposition algorithm.•Voltage stability is assessed by QV curve analysis on the buses of concern.•RB-SCOPF outperforms SCOPF on voltage instability performance.•The main reason is system flows are more uniformly distributed under RB-SCOPF.

This paper uses QV curve analysis to investigate the voltage instability performance of risk-based security-constrained optimal power flow (RB-SCOPF), where risk is modeled to capture the system's overall security level. The RB-SCOPF is an improvement of the traditional security-constrained optimal power flow (SCOPF) model. In previous works, we have demonstrated that the operating conditions obtained from RB-SCOPF were more secure (less risky) than those obtained from SCOPF. This raises the question of whether the RB-SCOPF operating condition is more stable than the SCOPF-operating condition for a power system. We respond to this question by comparing the voltage stability performance of operating conditions obtained from RB-SCOPF and SCOPF. We employ a practical algorithm to obtain the QV curves at the buses of concern and calculate the reactive power reserves associated with each bus for operating conditions obtained from RB-SCOPF and SCOPF, respectively. Test results for IEEE 30-bus system are presented to illustrate that RB-SCOPF has better voltage instability performance than SCOPF.