Analysis of Metrological Requirements for Electrical Measurement of HVDC Station Losses

Losses of HVDC converter stations need to be accurately measured and/or estimated in order to support the evaluation of bids for such systems and to underpin efforts to reduce greenhouse gas emissions. The challenge of measurement has risen with modern converters where insulated gate bipolar transistors (IGBT) are used at high switching frequency. The theoretical bases for measurement errors are studied, both for measurement on the IGBT as a component and on complete converter stations. The study shows that electrical measurements are difficult to augment to an accuracy level sufficient for the needs and that a supplemental method such as calorimetric measurement may be needed. In certain cases, there will be a possibility to make temporary connections to permit two converters to operate in back-to-back mode, permitting a direct measurement of losses. The achievable accuracy is studied and estimated.