High voltage direct current (HVDC) transmission systems are a key tool in extending the capacity of electricity grids and integrating sustainable energy from remote locations into the existing network. This EMRP project brought together eight NMIs and DIs to develop the metrological infrastructure to support a wide implementation of HVDC transmission in Europe. The research addressed metrological challenges that support a reduction of losses in HVDC transmission, ease the introduction of renewable energy sources, enhance the stability of electric power grids, support low loss, long distance energy transmission and ensure fair trade between organisations employing the grid.
The project developed:
- Improved measurement of power loss. State-of-the-art methods and instrumentation to evaluate losses in AC DC converter values (the key source of losses) were developed, as well as techniques to estimate the losses at the design stage, in order to support the needs of systems designers. The ability to identify and reduce losses has a direct impact on fuel use and greenhouse gas emissions.
- Improved capabilities in high voltage measurements. The measurement range was extended from a few 100 kV to 1000 kV and the uncertainties decreased substantially (to 0.005 %) in order to support accurate electricity metering and loss determination. A system suitable for on-site calibration was developed and tested at HVDC converter stations in Europe and Japan.
- New methods to assess the causes and effects of poor power quality were developed and tested on-site at HVDC stations. These methods assessed harmonics and inter-harmonics introduced into the grid system by the HVDC converter values. The knowledge generated will enable the design of appropriate filters to improve power quality and prevent component failure.
- Development of calibration methods and test systems for DC meters. Calibration services for primary current and voltage transducers for revenue metering on the DC side of converter stations have been created. Accurate metering is essential for the trading of electricity between commercial partners. A prototype DC energy meter was developed and demonstrated at the Lindome Scanlink 1 HVDC Station, proving that DC.-side metering is feasible. The specifications and test methods for DC side electricity meters have been identified and suggested for future inclusion in publicly available written standards.
The project worked closely with HVDC operators and equipment manufacturers to understand needs and test solutions on-site in HVDC converter stations. As a result, an electricity transmission system operator now refers to methods developed in the project to define verification of losses in its procurement specifications for a new HVDC intertie, and the Swedish NMI, SP, has been awarded a contract to perform the measurements. The long-term measurement campaign in a HVDC system converter station has yielded a vast amount of power quality that is available for further studies and analysis. Documentary standards are an important route to the use of best practice and the project’s outputs have been used in the preparation of an IEC standard for loss evaluation of voltage source convertors.
- EMRP Energy Theme impact case studies