Programming of Simplified Models of Flexible Alternating Current Transmission System (FACTS) Devices Using DIgSILENT Simulation Language

Abstract

An electric power system (EPS) must meet certain requirements that allow a continuous supply of demand at minimum cost and with the least environmental impact. For this purpose, several system controllers, such as the flexible alternating current transmission system (FACTS) devices, might be integrated into the grid, and so they should be included as part of the power system modelling in simulation programs. The addition of a new device in the transmission grid requires several studies that consider the analysis of the system for a wide variety of normal and stressed operating conditions, including maintenance situations. Thus, the integration of FACTS devices in the transmission network requires the development of static studies and dynamic analysis concerning stability simulation. These types of studies are important for proper system planning and operation. Although DIgSILENT PowerFactory has several dynamic models to represent to a number of power system components, its model library does not include a sufficient variety of dynamic models of FACTS devices. Only the model of the static var system (SVS) is already included in its library. However, in addition to typical functions for power system analysis, DIgSILENT PowerFactory offers versatility to model new components using its programming language DIgSILENT simulation language (DSL). The present chapter describes the methodology for including the following models of FACTS devices into DIgSILENT PowerFactory: thyristor controlled series compensator (TCSC), static series synchronous compensator (SSSC), static synchronous compensator (STATCOM) and unified power flow controller (UPFC). Additionally, power oscillation damper (POD) is also incorporated into the models in order to improve oscillatory conditions. The models that will be described correspond to the so-called simplified models that are designed to be used in stability studies of EPSs (i.e. electromechanical transients). Finally, simulations are performed in a test power system that show the dynamic behaviour of the implemented FACTS devices and allow their corresponding validation.