The electric power system on the British Isles was among the first to be deregulated, a decade or so ago. As a consequence the generation became more independent from grid operation and other means had to be introduced in order to safeguard the stablility of the grid. Particularly as generation dispatch could change drastically, the criteria for grid stability changed over time. Some flexible means of grid support was urgently needed and FACTS was called upon.
Four Relocatable Static Var Compensators (RSVC), supplied by ABB, has been commissioned to the National Grid Company’s 400/275 kV power transmission network. The compensators, all having a dynamic rating of 0-60 Mvar, are located in the Midland area. The SVCs have been designed to be connected to the 13 kV tertiary windings of existing substation autotransformers. The operating range of the compensators is achieved by means of Thyristor-Switched Capacitors (TSC) exclusively.
The truly relocatable design of ABBs RSVC enables full relocation of each installation from one place in the grid to another within just a few weeks, depending on local conditions. The relocatability was a customer requirement driven by the need to achieve flexible grid support.