Voltage-sourced converter based FACTS controllers, modelling, dispatch, computation, and control.

摘要

Flexible AC Transmission System (FACTS) Controllers offer potentials to directly control flows and voltages on an ac network. A newer generation of FACTS Controllers based on voltage-sourced converters (VSC) provides fast controllable shunt and series voltage injections into the ac network, with which further enhancement in controllability and power transfer capability can be achieved.; In this research work, we tackle the problems of modeling, dispatching, and control of various VSC-based FACTS Controllers, including the Static Synchronous Compensator (STATCOM), Static Synchronous Series Compensator (SSSC), Unified Power Flow Controller (UPFC), Interline Power Flow Controller (IPFC), and Generalized Unified Power Flow Controller (GUPFC). We use the injected shunt and series voltage sources to model the VSC-based FACTS controllers. This offers a common modeling framework, based on which a Newton-Raphson loadflow solution and a network sensitivity analysis tool can be readily developed. The FACTS Controller sensitivities, similar to generator shift factors affecting network flows, provide a linear estimate of the effect of the FACTS control variables on the network variables, and are useful for the analysis and optimal dispatch of FACTS Controllers. Using the sensitivity analysis, methodologies for dispatch optimizations, including voltage dispatch, power dispatch, and maximizing power transfer, are presented.; When FACTS Controllers operate at the rated capacity, advanced dispatch strategies are required because voltage and power setpoint enforcement of the FACTS Controllers are no longer possible. A dispatch strategy for the UPFC operating at rated capacity is presented, in which the circulating power between the coupled VSCs is used as the parameter to co-optimize the coupled shunt and series VSCs, while respecting the operational constraints. A similar strategy using the power circulation regulation is also proposed for the IPFC. Voltage stability curves are used to illustrate the effectiveness of the strategy to maximize voltage-stability limited power transfer. An automatic control system is proposed to implement the power circulation dispatch strategy in real-time for both normal operation and rated capacity conditions.