Risk-based framework for assessment of operational constraints for power systems focusing on small-disturbance stability and sub-synchronous resonance

This paper presents a risk-based framework to establish operational constraints for modern power systems. The methodology is established and subsequently applied to two areas of power system analysis - small-disturbance stability and sub-synchronous resonance (SSR). In the first case, probability density functions (pdfs) for critical oscillatory electromechanical modes are established based on the stochastic variation of system uncertainties such as generation and loading. These pdfs provide probabilities of unstable or poorly damped oscillations that are evaluated using risk-based approaches. For SSR analysis, frequency scans are completed to identify generators which are at risk of experiencing high mechanical torques. In both cases, evaluation using severity functions is used to ensure that acceptable levels of risk are not exceeded. The proposed methods are demonstrated using a meshed power system with capacitor series compensated AC tie lines.