Commissioning of a 225 Mvar SVC incorporating A ±75 Mvar STATCOM at NGC´s 400 kV East Claydon substation

In view of the many system planning uncertainties faced by the UK National Grid Company (NGC), there is a clear need for readily relocatable reactive power compensation systems with enhanced system performance. To date 12 relocatable SVCs (RSVCs) have been installed as part of a planned programme of work to meet these changing system needs. Developments in the rating capabilities of gate turn-off (GTO) thyristors have enabled power electronic converters using GTOs to be proposed as serious competitive alternatives to the well proven thyristor controlled reactor (TCR) and thyristor switched capacitor (TSC). GTO-based STATCOM convertors have a number of benefits which are of value to NGC, such as reduction in required site area and ease of relocation. The authors describe the East Claydon project, which is viewed as an important step towards long-term objectives which could see the deployment of a range of compact power electronic devices on NGC´s system.