Lcc 3 hvdc classic current source converters csc linecommutated converter lcc with thyristor valves requires 50% reactive compensation 35% hf converter transformers minimum short circuit capacity 2 x pd, 1. Hvdc transformers are used for selfcommutated voltagesourced converters. Brazil, hvdc backtoback system was chosen to ensure supply of 50 hz bulk mw power to a 60 hz system under a 20year power supply contract. Hvdc circuit breakers are difficult some mechanism must be included in the circuit breaker to force current to zero. Converter transients, imposed on hvdc converter transformers, can produce voltages and currents which result in equipment failure. Mainly due to the extra conversion equipment and maintenance difficulty.
Hvdc is an established technology that has been in. Jun 20, 2012 abb is building the riomadeira hvdc power superhighway that will bring clean hydropower from porto velho in the northwest to sao paulo, brazils main economic center covering a distance of more. Abb and hvdc the worlds first commercial highvoltage direct current hvdc link, situated between the swedish mainland and the island gotland, was delivered by abb already in the 1950s. Hvdc converter transformers xdge has developed the hvdc converter transformer designs up to the maximum 800kv voltage level and has produced a large number of hvdc converter transformers. As a key enabler in the future energy system based on renewables, hvdc is truly shaping the grid of the future. Abb successfully developed and tested 1,100 kv converter transformer technology breaking the record for the highest dc voltage levels ever. Home complianceonline standards iso ics 21 mechanical systems and components for general use convertor transformers part 2. Hvdc bipolar system layout hvdc rectifier and invertor station in hvdc bipolar systems consists of following parts 1. Improving power reliability for millions of west coast residents the worlds largest hvdc converter transformers provided to a major link in the us the owners of the celilo converter station decided to refurbish and upgrade the station capacity to 3,800 mw. What is the difference between a converter transformer.
Hvdc transformer brochure digital asset management. Reduced emission painting for transformers brochure english pdf brochure. Summary a highvoltage, direct current hvdc system also called a power superhighway or an electrical superhighway uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current ac systems. Markus pettersson, september 22, 2016 plnabb power grids. The system which uses the direct current for the transmission of the power such type of system is called hvdc high voltage direct current system. Abb hvdc transformers are at the heart of these systems. An hvdc converter converts electric power from high voltage alternating current ac to highvoltage direct current hvdc, or vice versa. Guide to high voltage direct current hvdc transmission on photo. The valves are protected using snubber circuits, gapless surge arrestors, and protective firing circuits. Siemens at that time, conversion between reasonable consumer voltages and higher dc transmission voltages could only be realized by means of rotating dc machines. Hvdc transmission line has less right of way requirement. Hvdc classic transformers are the heart of hvdc transmission systems.
As all generating stations are generating power in ac, we are in need to convert this ac to hvdc. Principles of hvdc controls control of dc voltage dc voltage is varied by means of a converter bridge in rectifier operation the power flow is from the ac system to the dc system the power flow is changed from the dc system to the ac system by reversing the dc voltage. Abb to deliver hvdc converter transformers to chinese utility sgcc. Dec 06, 20 application based hvdc transmission types upto 3000 mw hvdc represents the most economical solution to transmit electrical energy over distances greater than approx. Insultion provided for converter transformer is very high as it needs to withstand voltage stress under both ac and dc condition. A monopolar hvdc system with ground return consists of one or more sixpulse converter units in series or parallel at each end, a single conductor and return through the earth or sea, as shown in figure 2. Hvdc transformers are also used to ensure an appropriate tapping range for part of the dc voltage and for reactive power. The use of dc transformers brings benefits in terms of better resilience from tap system faults, more flexibility in power reversal, an additional control channel and lower costs for main acdc converter and transformer. A highvoltage, direct current hvdc electric power transmission system also called a power superhighway or an electrical superhighway uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current ac systems. High voltage direct current hvdctransmission systems. It transmits the power between the unsynchronized ac system. A new voltage level is introduced with a transmission voltage of 800 kv for highvoltage dc transmission. The commutation capacitors improve the commutation failure performance of the.
Tapping on hvdc lines using dc transformers sciencedirect. High voltage direct current hvdc transmission finally proved to be technically feasible. The development, design and production of hvdc transformers differ from those of. This paper investigates a new topology for tap terminals on hvdc transmission, which is based on highpower dcdc converters. Main duct in hvdc transformers require more pb barriers than normal. For long distance transmission of power, hvdc transmissions are more economical than ac. Hvdc transformers are normally singlephase transformers, whereby the valve windings for the star and delta connection are configured either for one core with at least two main limbs or separately for two cores with at least one main limb, depending on the rated power and the system voltage. Applications for high voltage direct current hvdc transmission technologies april 22, 20 nreca conference center. Topics associated with dc transmission have been included, in detail, to support this study. High voltage direct current hvdc line commutated converter lcc systems have been in operation for over 50 years. Alstom grid 256 mva, 3phase, 358 kv hvdc transformer on test. In hvdc plus monopole applications, no dc voltage stresses occurs at the transformer valve terminals. Manufacturers can standardize their product portfolios utilities can have the same equipment for several converter stations same voltage level increased insulation margins for e. Siemens delivers hvdc plus converter transformers for transmission lines up to 1,200 mw, up to 500 kv dc with connections to ac grids up to 525 kv.
The role of hvdc transformers hvdc transformers are at the heart of hvdc transmission systems. Transformers for hvdc applications document number. A remarkable journey transportation of the worlds largest. In large emerging countries such as the bric countries, hvdc cables already transmit several gw of electric power at up to 800 kv over thousands of kilometers. Hvdc is used as an alternative to ac for transmitting electrical energy over long distances or between ac power systems of different frequencies. Abb has delivered more than 75 of these projects with a total transmission capacity of almost 60,000 mw.
Pros and cons with standard insulation levels for hvdc pros. Abb has participated in the delivery of more than half of the worlds around 170 hvdc links. It interconnects the networks that have different frequencies and characteristics. Hvdc converter transformers are the heart of hvdc transmission systems. With the transmission power capability of hvdc systems steadily on the rise, requirements for converter transformer technology and design have greatly increased. Application based hvdc transmission types upto 3000 mw hvdc represents the most economical solution to transmit electrical energy over distances greater than approx.
It converts direct current to alternating current or the reverse. The transformers used before the rectification of ac in hvdc system are called as converter transformers. Pdf 800 kv ultra hvdc transformer a new dimension of dc. Hvdc classic converter transformers hvdc converter. Guide to high voltage direct current hvdc transmission. Abbs hvdc transformer and highvoltage technology will integrate largescale renewables in china. Siemens at that time, conversion between reasonable consumer voltages and higher dc transmission voltages could only be. The ultra high voltage uhv technology is an advancement of hvdc, transmitting large amount of power with minimum losses and integrating renewables often located at a great distance from centers of the demand.
Abb library is a web tool for searching for documents related to abb products and services. In addition to the converter, the station usually contains. Markus pettersson, september 22, 2016 plnabb power. Main feature chapter iii making energy available to all. What is hvdc high voltage direct current transmission. Economical even for shorter distances such as a few 10kmmiles 23. The light signals further converted into electrical signals using gate drive amplifiers with pulse transformers. The worlds largest hvdc converter transformers provided to. Sep 24, 2014 converter transformers used in high voltage direct current hvdc system are specially designed power transformers of high mva rating connected between ac bus bar and converter valves. For short distance transmission of power, ac transmissions are widely prefered. High voltage dc transmission system electronics hub.
Specific design of converter transformers for hvdc. Large hvdc transmission schemes having power transmission capacities of. Application based hvdc transmission types hvdc is an alternative for submarine transmission. In gotland, sweden, hvdc was chosen to connect a newly developed wind power site to the main city of visby, in consideration of the environmental sensitivity of the project area an. Converter transients imposed on hvdc converter transformers. Power transformers hvdc transformers building trust through a. Abb designed, manufactured and tested the worlds largest hvdc converter transformers for the project. Special converter transformers are the key components of hvdc transmission systems. Developments in uhvdc and uhvac transmission english pdf white paper. Hvdc light rating increase to 1100 mw elements common to existing systems igbt chip igbt submodule igbt stakpak igbt module or stack control system cooling system dc capacitor increased dc current six submodules per stakpak rather than four increased dc voltage 150 kv to 320 kv valve stacks comprised of igbt modules with 26 positions arranged horizontally. In total, about,000 mw hvdc transmission capacity is installed in more than 140 projects worldwide.
For longdistance transmission, hvdc systems may be less expensive and suffer lower electrical losses. A basic overview of a classic hvdc power transmission station based on lcc technology with the discovery and usage of semiconductor switching devices such as transistors, and particularly the thyristors in the 1960s, solidstate technology began to replace the older mercuryarc technology, bringing improved reliability and higher power ratings. Hvdc transmission based on current sourced converters has been in use for 50 years. Converter transformers used in high voltage direct current hvdc system are specially designed power transformers of high mva rating connected between ac bus bar and converter valves. Reactors for hvdc transmission systems hvdc transformers transformers and smoothing reactors for bulk power transmission systems up to 800 kv dc transformers for dc coupling of different ac networks castresin distribution and power transformers geafol 100 kva to more than 40 mva, highest voltage for equipment up to 36 kv, of 3phase or 1phase. An hvdc converter station or simply converter station is a specialised type of substation which forms the terminal equipment for a highvoltage direct current hvdc transmission line. Power transformers hvdc transformers building trust. Skan%202%20hvdc%20pole%20with%20an %20upgrade%20of%20the%20existing%20fennoskan%201%20. Hvdc is the technology of choice for efficiently transporting power over long distances 400 km and with sea cables. In backtoback hvdc stations, the converters and rectifiers are installed in the same stations.
The worlds first commercial hvdc transmission link, was built in 1954 between the swedish mainland and the island of gotland, with a rating of 20 mw, 200 a and 100 kv. Transformer saturation occurs due to voltage recovery after a. Hvdc transformers are either built as singlephase or three phase units as per our requirement. A highvoltage, direct current hvdc system also called a power superhighway or an electrical superhighway uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current ac systems. Hvdc highvoltage direct current is a highly efficient alternative for transmitting large amounts of electricity over long distances and for special purpose applications. At present there are more than 100 systems in operation transmitting more than 100 000 mw of power. The hvdc system which transfers energy between the ac buses at the same location is called backtoback system or an hvdc coupling system. Hvdc transmission is a comprehensive text that facilitates indepth study of hvdc transmission, including inception, working principles, advantages and disadvantages, and stateoftheart hvdc transmission systems. High voltage direct current hvdc power systems use d. In a high voltage direct current hvdc system, electric power is taken from one point in a threephase ac network, converted to dc in a converter station, transmitted to the receiving point by an overhead line or cable and then converted back to ac in another converter station and injected into the receiving ac network. Pdf 800 kv ultra hvdc transformer a new dimension of. A total of seven single phase, 770 mva 3winding transformers, were designed to fit in the existing area, which reduced the complexity of the installation and commissioning of the converter station. The windings of the converter transformer on the ac line side are called line winding and the windings on the converter valve side are called valve.
Oct 29, 2015 high voltage dc transmission system october 29, 2015 by administrator 1 comment when a bulk power is to be transported over very long distances, or under water, hvdc transmission system is used which is more economical compared to ac transmission system. Todays hvdc power system in general has to be ac, because there is no dc transformers therefore todays hvdc involves conversion of ac to dc and back to ac to justify hvdc, there needs to be. Hvdc converters capable of converting up to two gigawatts gw and with voltage ratings of. Design considerations of ultra high voltage dc system siemens ag. For longdistance power transmission, hvdc lines are less expensive, and losses are less as compared to ac transmission. Hvdc disadvantages hvdc is generally less reliable and has lower availability than hvac. These two transformers are almost same design except 1. Hvdc classic converter transformers up to 12 gw gigawatt and 80 kv 1,100 kv direct current dc and 1,200 kv alternating current ac hvdc light converter transformers up to 1,500 mw and.
Their main application is to transfer power between an ac system and the dc transmission network. Hvdc converter transformers power transformers abb. Abb pioneered hvdc technology and is the world leader in the hvdc field. The operating range of the ideal converter theory from. Inverter ud control no change in dc voltage, but change in dc current. For longdistance transmission, hvdc systems may be less expensive and have lower electrical losses. Hvdc converter transformers the backbone of reliable power supply. The application of increasing voltage levels together with the continuous application of. Ac transformers as dc voltage is taken mainly by pb. Available for download link will be provided in my complianceonline section. Abbs first 800 kv hvdc transformer successfully tested worlds highestvoltage power link with record capacity of 6. Plains and eastern hvdc clean line energy partners report r8.