In contingency analysis, what does N-1 mean?

In contingency analysis, what does N-1 mean?

• A. The loss of any single component should not compromise system security
• B. Only one generator failure is considered
• C. Only one transmission line is shut down
• D. All components must be online

Answer: (A)

In contingency analysis, the N-1 criterion means the system must remain secure if any single component fails. This requires checking, for every possible single outage—such as a generator going offline or a transmission line dropping out—that the remaining system can meet demand without violating voltage limits or line flow limits. The answer that captures this idea states that the loss of any single component should not compromise system security, which directly reflects the N-1 requirement. It isn’t limited to generator outages or to one type of element, and it doesn’t demand that all components stay online, since the whole point is to tolerate a single failure. This principle helps operators ensure reliability by preparing for one failure at a time.

In contingency analysis, the N-1 criterion means the system must remain secure if any single component fails. This requires checking, for every possible single outage—such as a generator going offline or a transmission line dropping out—that the remaining system can meet demand without violating voltage limits or line flow limits. The answer that captures this idea states that the loss of any single component should not compromise system security, which directly reflects the N-1 requirement. It isn’t limited to generator outages or to one type of element, and it doesn’t demand that all components stay online, since the whole point is to tolerate a single failure. This principle helps operators ensure reliability by preparing for one failure at a time.