Aspects of series controlled flexible AC transmission system planning and operation

Planning and operational aspects of a static synchronous series compensator (SSSC) applied to increase the utilisation of a transmission system are discussed. It is shown that planning of flexible AC transmission systems (FACTS) requires detailed and comprehensive system modelling and analysis. A process structure to design and specify a series FACTS device illustrates the relationship between the major analysis activities and the data, which are derived from operational needs. In accordance with the design process, a metal oxide varistor (MOV) based SSSC protection scheme and a control strategy to regulate the current flow in a transmission line is introduced. Test results demonstrate the application of the proposed control strategy, which has been implemented on a digital signal processor system (DSP) to control an experimental model of a 24-pulse SSSC. Power quality aspects are also considered.