Operational security criterion of a smart grid

Traditional N-1 security assessment is carried out by analysing a predefined set of credible contingencies and enforcing a threshold criterion of acceptable risk on system variables based on standard operating practices. The system is eventually despatched to avoid the occurrence of worst-case scenario among the credible contingency set. This rudimentary risk-avoidance approach has served the power industry tolerably for so many years due to heavy computational burdens involved in security analysis as well as the difficulty of communicating outage statistics and risk indices of various components in operation timescales. As power systems will soon be flirting with smart grid technologies that offer advanced sensing and telecommunication capabilities, it is prudent to leverage existing deterministic N-1 security criterion to a risk-based security management to realise the premise of a smart grid. The paper highlights the drawbacks of the N-1 contingency criterion and introduces some concepts of risk-based analysis for the potential application in determining power system operational security level.