VOLTAGE STABILITY ANALYSIS ON THE NGC SYSTEM

The reactive power requirements on the National Grid Company (NGC) sys tem have risen as a result of increased power flows and the shorter ti mescale on which power stations are commissioned and withdrawn from se rvice. Power transfers across internal system boundaries are found in some cases to be determined by voltage limits and the need to avoid vo ltage collapse, rather than thermal capability of the transmission pla nt. Analytical techniques for voltage stability analyses have been und er investigation with the ultimate objective of providing better tools for operational planning and operation. This paper describes the deve lopment of a method for voltage stability analysis using improved sens itivity techniques to rapidly calculate the transfer limit of any defi ned boundary. This is extended to include the modelling of synchronous compensators and static var compensators (SVCs), as well as on-load t ap changers. Extensive testings of the algorithm are carried out on th e NGC test systems. (C) 1998 Elsevier Science S.A. All rights reserved .