A STATCOM-based relocatable SVC project in the UK for National Grid

As part of a programme of investment in relocatable reactive compensation in the UK, National Grid initiated a project to deliver a static VAr compensator (SVC) for its East Claydon substation in Buckinghamshire. The SVC includes a ±75 MVAr STATCOM and is viewed as an important step towards long-term objectives intended to encourage new technologies with the potential to improve the efficiency and security of its system. This paper outlines the requirements for reactive compensation in the UK and the need for a SVC at East Claydon. The basic design of the SVC is described with particular focus on the STATCOM. 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.