Power system reliability

The power system reliability (sometimes grid reliability) is the probability of a normal operation of the electrical grid at a given time. Reliability indices characterize the ability of the electrical system to supply customers with electricity as needed by measuring the frequency, duration, and scale of supply interruptions. Traditionally two interdependent components of the power system reliability are considered:

• power system adequacy, a presence in the system of sufficient amounts of generation and transmission capacity;
• power system security (also called operational reliability), an ability of the system to withstand real-time contingencies (adverse events, e.g., an unexpected loss of generation capacity).

Ability of the system to limit the scale and duration of an power interruptions is called resiliency. The same term is also used to describe the reaction of the system to the truly catastrophic events.