The application of a relocatable STATCOM-based SVC on the UK National Grid system

As part of a programme of investment in relocatable reactive compensation in the UK, National Grid initiated a project to deliver a STATCOM-based static VAr compensator (SVC) for its 400 kV East Claydon substation. STATCOM technology has a range of advantages which are of increasing value to National Grid given the uncertain system planning environment in which it now operates. This paper describes the innovative STATCOM technology which has been successfully developed and put in to commercial service as part of this project. The paper outlines the need for a SVC at East Claydon and its basic design. The novel chain-circuit topology is used for the GTO-based STATCOM to provide a compact voltage-sourced convertor with low losses and the capability for single-phase operation to match prevailing system conditions. The commissioning of the STATCOM-based SVC is summarized with reference to site records of response tests and harmonic voltage measurements.