Modelling plant for flexible AC transmission systems

To achieve a flexible AC transmission system (FACTS) requires the insertion of plant to control system voltage magnitude and phase. Most of this plant is electronic and depends upon properly coordinated control action. Modelling is used to generate confidence and the type of modelling must reflect the principles to be demonstrated and plant characteristics. Here, the authors describe how modeling may take the form of digital computer models which are convenient to use but which ignore some operating conditions or physical models which, whilst not so convenient to use and which are more expensive to give a more detailed prediction of performance. Within these broad categories there is a range of models available which are identified