Enhancement of power system security level using FACTS controllers and emerging energy storage technologies

Abstract

Energy security is jointly with economy one of the most important requirements during the operation of the electric power system (EPS). However, many large blackouts happened worldwide in the last decade with serious economic losses allows concluding that security of existing power systems is poor and should be improved. Primary frequency control (PFC) is one of the important means to ensure power system security. It can regulate short period random variations of frequency during normal operation conditions and response to emergency rapidly. An alternative to enhance the PFC and thus security is to store exceeding energy during off-peak load periods in efficient energy storage systems (ESSs) for substituting the primary control reserve. In this sense, ESSs in combination with flexible AC transmission system (FACTS) controllers are capable of supplying power systems with both active and reactive powers simultaneously and very fast, and thus are able to enhance the security dramatically. In this chapter, a new concept of PFC for improving the EPS security level based on incorporating a FACTS device coupled with emerging ESS systems is thoroughly presented. More specifically, of the various advanced FACTS devices and emerging energy storage systems nowadays existing, the combination of a static synchronous compensator (STATCOM) with the three foremost ESSs for EPS power level applications are considered, i.e. ultra capacitors, SMESs and flywheels. To this aim, major operating characteristics of these modern devices are firstly analyzed and a detailed modeling approach is presented. Moreover, a simplified state-space averaged mathematical model of the combined STATCOM-ESS controller is provided. By using concepts of instantaneous power on the synchronousrotating d-q reference frame, a novel three-level control scheme is then proposed for improving the EPS security level. Eventually, the dynamic behavior of the presented models and control algorithms is fully evaluated through a computational implementation in the MATLAB/Simulink environment using the SimPowerSystems blockset. The results obtained demonstrate the excellent dynamic performance of the STATCOM-ESS as well as the benefits of its use in the improvement of the EPS security.