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Innovative solutions with HVDC (High Voltage Direct Current) and FACTS (Flexible AC Transmission Systems)have the potential to cope with the system planning and operational challenges of global climate developments and the call for changes in the way electricity is supplied. New power electronic technologies with self-commutated converters make advanced technical features possible, such as independent control of active and reactive power, and the capability to supply weak or passive networks. As part of the overall planning considerations, this paper presents the fundamental system planning, modeling and operational challenges of connecting large wind farms (both onshore and offshore) via long transmission systems, as well as the practical applications of traditional and new power electronic technologies.

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 ± ± ± ±75Mvar 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.

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Turbine specialists have extensive experience in the analysis and interpretation of turbine–generator operational plant data and in the diagnosis of fault conditions. Expert system technology makes it possible for such expertise, elicited from specialists, to be structured in a ‘knowledge base’. This paper will discuss the application of specialist knowledge to the analysis of turbine–generator plant data to aid turbine staff of optimize plant performance, thus demonstrating to users the operation and potential benefits of a consultative expert system.