Transient stability in a power system refers to its ability to maintain synchronous operation following a disturbance, such as a fault or sudden change in operating conditions. It specifically relates to the system's capability to withstand and recover from transient disturbances without losing synchronism or experiencing a cascading failure that leads to a widespread blackout.
When a fault occurs or a major disturbance happens, there is an abrupt change in the electrical parameters of the power system, including voltage, current, and power flow. These changes can cause a temporary loss of stability and result in large swings in rotor angles and speeds of synchronous machines, such as generators.
Transient stability analysis involves studying the dynamic response of the power system during and after a disturbance, typically by simulating the system's behavior using mathematical models. This analysis helps determine if the system can withstand the disturbance and maintain stable operation or if it will diverge and lead to an unstable condition.
Maintaining transient stability is crucial for ensuring the reliable and secure operation of a power system. If the system loses transient stability, it can lead to cascading failures, where subsequent generators trip offline due to the imbalance between power generation and demand. Ultimately, this can result in a widespread blackout affecting a large area.
Various measures can be taken to enhance transient stability, such as installing power system stabilizers (PSS) on generators, employing fast-acting protective relays, and implementing appropriate control strategies. These measures aim to minimize the impact of disturbances and enable the power system to recover and regain stable operation quickly.