SVC refurbishment experience for critical coal train haulage network

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By June 2009, Powerlink Queensland of Australia will have nineteen (19) Static Var Compensators (SVCs) in service and they provide 3871 MVArs of Dynamic Reactive Power Support to the Queensland transmission network. Ten (10) of these SVCs have been in service since 1987 at substations supplying two phase supply to railway traction loads. Over the last 20 years, these SVCs have provided the critical Negative Phase Sequence (NPS) balance support to the railway electrification network in Central Queensland, Australia. Aging secondary system components have been responsible for some failures and network interruption in recent years. SVC failures causing power transfer limits in the operational network are major concerns and can affect the Australian coal export capability. Recognising the need to refurbish these old SVC components to achieve adequate reliability is an important aspect of Asset Management and Network Operation. This paper describes in detail the refurbishment process for ten (10) aging SVCs at railway electrification sites. Understanding the critical failure modes and using this information to determine detailed design parameters for different SVC components is a great engineering challenge. The refurbishment processes include study of SVC failure modes, operational network constraints, specification, network modelling, design, testing, implementation, challenges and solutions to overcome challenges. Practical experiences learnt from a difficult yet successful refurbishment project are documented. Over the last 3 years, Powerlink Queensland has worked together with Siemens Limited and successfully refurbished ten (10) SVCs in Central Queensland, Australia, without interruption to the electrified coal train network.