FACTS devices modeling in real-time dynamic control of power systems

Dynamic loads of high capacity power grids under normal and severe conditions are the most concerns of system operators and dispatchers to maintain voltage stability. Reactive power (Q) are often drawn by loads from various generated sources disturbing the operational power factor. Compensating methods are used, depending on load types and their reactive power patterns, to continuously monitor and correctly counteract fast changes by extremely rapid VAR compensation especially during transient conditions. Using power electronics and combining both, power and control engineering, some FACTS devises equipped with selected power electronic switching are the appropriate methods to respond to system variations in almost no time. STATCOM regulates system voltages based on a voltage-source converters, by absorbing or generating reactive power. Contrary to a thyristor-based Static VAR Compensator (SVC), STATCOM output current (inductive or capacitive) can be controlled independent of the system voltage. This paper presents a design of voltage controller to analyze and validate the dynamic behavior of FACTS device (STATCOM)in riding through severe transient imbalance using a powerful computer simulation application “PSCAD EMTDC”. The STATCOM was modeled in 3-Phase network with various parameters in a steady state condition and during a short interval of system fault. The regulator provided the ride through during severe transient while maintaining sufficient bandwidth to perform necessary compensations. The controller behavior is simulated in distribution system model while it was subjected to severe three phases to ground fault with rapidly varying three phase load.