Prevention of transient voltage instabilities due to induction motor loads by static VAr compensators

The application of static VAr compensators (SVC) to prevent transient voltage instability due to the presence of large induction loads at the terminals of long transmission lines is discussed. Eigenvalue analysis is used to identify the conditions for voltage instability. The analysis is supported by transient time simulations for the complete power system following large disturbances. It is found that SVC can obviate transient voltage instabilities and maintain the load voltage near its rated value. It is shown that replacing the SVC with mechanically switched capacitors may not provide stabilization owing to the time delays associated with voltage drop detection and breaker operation