That makes them a good choice for offshore wind farms. “They require maybe 30% of the area of a conventional converter and about 50% of the weight,” Curci said. Vince Curci, underground transmission project manager with HDR, said one of the advantages of VSC technology is that it is very compact. All HVDC manufacturers are applying MMC technology in VSCs today. MMC technology offers excellent harmonic performance and reduced power losses compared to previous VSCs. The Trans Bay Cable project, which runs between San Francisco and Pittsburg, California, was completed in 2010, using Siemens’ HVDC Plus system. VSC technology was further improved when Siemens introduced a modular multilevel converter (MMC). ABB named its new VSC-based product HVDC Light. An IGBTs high switching frequency capability allows more-precise VSC control and less-complex circuit configuration through the use of pulse width modulation techniques. VSC technology uses gate turn-off switching devices, such as insulated-gate bipolar transistors (IGBTs), to perform the conversion. In 1997, ABB commissioned the world’s first HVDC demonstration project using voltage source converters (VSCs). The service was re-engineered in 1970, increasing capacity to 30 MW at a voltage of 150 kV through the addition of a thyristor valve bridge.ĪSEA continued to push boundaries, developing new HVDC systems during the decades that followed. The original Gotland link could transfer 20 MW over a 98-kilometer (km)-long submarine cable with a voltage of 100 kV. In 1954, ASEA, the predecessor of ABB, used this classic technology utilizing mercury arc valves to construct the world’s first commercial HVDC link between Västervik, on the east coast of Sweden, and Ygne, on the island of Gotland in the Baltic Sea. Conventional HVDC converter technology is based on the use of line-commutated or phase-commutated converters. Electrical pioneers were working on the building blocks for HVDC-links back in the late 1800s. First, the AC power must be converted to DC to begin the transmission process, and then when it gets to the desired tie-in destination, the DC power must be converted back to AC to be utilized on the grid.Ĭonversion technology is well-established. The challenge, however, is that to transmit via HVDC, two converter stations are needed. “If the transmission line route is longer than about 300 miles, DC is a better option because AC lines have more line losses than DC for bulk power transfer.” Converting from AC to DC “One big advantage to HVDC is the efficiency of power transmission over long distances,” George Culbertson, vice president of power delivery markets for HDR, told POWER. However, there are instances when high-voltage direct current (HVDC) transmission systems offer significant benefits. Thus, the majority of transmission lines carrying power around the world are of the AC type. Typical utility-scale power plants generate alternating current (AC) electricity, and most electrical loads run on AC power. Once installed, HVDC transmission systems are an integral part of the electrical power system, improving stability, reliability, and transmission capacity. However, cost is an important variable in the equation. For example, it allows more efficient bulk power transfer over long distances. Information on the effects of electric and magnetic fields can be found here.High-voltage direct current (HVDC) technology offers several advantages compared to alternating current transmission systems. We make sure that the electric and magnetic fields caused by transmission lines remain below the recommended maximum values, and we have released a related statement on electric and magnetic fields. Here you can find out more about Fingrid's transmission line projects as a landowner and participate in planning (in Finnish). The assessment also takes into account the corona noise caused by the transmission line, as well as concerns relating to the possible health effects of electric and magnetic fields. In the Environmental Impact Assessment procedure for transmission line projects, the impacts on people's living conditions, living comfort and health are assessed. In the planning of new transmission line routes, our aim is to avoid the proximity of residential areas, day-care centres, playgrounds and schools. In accordance with the nation-wide land use objectives, stipulated in the Land Use and Building Act, the objective is to primarily utilise existing rights-of-way. Find out more about the multiple uses of transmission line areas here. There are many different ways of utilising transmission line areas. The land and trees under a transmission line belong to the landowner.
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