Siemens at that time, conversion between reasonable consumer voltages and higher dc transmission voltages could only be realized by means of rotating dc machines. Special converter transformers are the key components of hvdc transmission systems. This paper investigates a new topology for tap terminals on hvdc transmission, which is based on highpower dcdc converters. Hvdc circuit breakers are difficult some mechanism must be included in the circuit breaker to force current to zero. 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.
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. The worlds largest hvdc converter transformers provided to. Home complianceonline standards iso ics 21 mechanical systems and components for general use convertor transformers part 2. 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. 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. What is hvdc high voltage direct current transmission.
Available for download link will be provided in my complianceonline section. 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. Hvdc converter transformers are the heart of hvdc transmission systems. Developments in uhvdc and uhvac transmission english pdf white paper. Specific design of converter transformers for hvdc. Hvdc is used as an alternative to ac for transmitting electrical energy over long distances or between ac power systems of different frequencies. These two transformers are almost same design except 1. 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. The application of increasing voltage levels together with the continuous application of. 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. The commutation capacitors improve the commutation failure performance of the. Abb to deliver hvdc converter transformers to chinese utility sgcc. Topics associated with dc transmission have been included, in detail, to support this study.
Main duct in hvdc transformers require more pb barriers than normal. Hvdc transformer brochure digital asset management. Hvdc transmission based on current sourced converters has been in use for 50 years. 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.
Alstom grid 256 mva, 3phase, 358 kv hvdc transformer on test. 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. Good question, let me explain you, being a hvdc engineer. Hvdc converter transformers power transformers abb. Hvdc transmission line has less right of way requirement. 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. In backtoback hvdc stations, the converters and rectifiers are installed in the same stations. Siemens at that time, conversion between reasonable consumer voltages and higher dc transmission voltages could only be.
Guide to high voltage direct current hvdc transmission. Hvdc classic transformers are the heart of hvdc transmission systems. Hvdc converter transformers the backbone of reliable power supply. These have been developed to support projects from 50kv hvdc backtoback converter stations up to 800kv hvdc transmission projects.
High voltage dc transmission system electronics hub. 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. Ac transformers as dc voltage is taken mainly by pb. What is the difference between a converter transformer. Insultion provided for converter transformer is very high as it needs to withstand voltage stress under both ac and dc condition. Converter transients, imposed on hvdc converter transformers, can produce voltages and currents which result in equipment failure. Abb pioneered hvdc technology and is the world leader in the hvdc field. Hvdc classic converter transformers hvdc converter. High voltage direct current hvdc power systems use d. The valves are protected using snubber circuits, gapless surge arrestors, and protective firing circuits. High voltage direct current hvdc line commutated converter lcc systems have been in operation for over 50 years. With the transmission power capability of hvdc systems steadily on the rise, requirements for converter transformer technology and design have greatly increased. Guide to high voltage direct current hvdc transmission on photo.
Pdf 800 kv ultra hvdc transformer a new dimension of. In hvdc plus monopole applications, no dc voltage stresses occurs at the transformer valve terminals. The hvdc system which transfers energy between the ac buses at the same location is called backtoback system or an hvdc coupling system. 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. Converter transients imposed on hvdc converter transformers.
For longdistance power transmission, hvdc lines are less expensive, and losses are less as compared to ac transmission. The role of hvdc transformers hvdc transformers are at the heart of hvdc transmission systems. Power transformers hvdc transformers building trust. For short distance transmission of power, ac transmissions are widely prefered. 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. It transmits the power between the unsynchronized ac system. 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 is the technology of choice for efficiently transporting power over long distances 400 km and with sea cables. Hvdc transformers are also used to ensure an appropriate tapping range for part of the dc voltage and for reactive power. Hvdc bipolar system layout hvdc rectifier and invertor station in hvdc bipolar systems consists of following parts 1.
A new voltage level is introduced with a transmission voltage of 800 kv for highvoltage dc transmission. It converts direct current to alternating current or the reverse. 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. The backtoback system provides an asynchronous interconnection between the. Hvdc is an established technology that has been in. As a key enabler in the future energy system based on renewables, hvdc is truly shaping the grid of the future. The development, design and production of hvdc transformers differ from those of. Skan%202%20hvdc%20pole%20with%20an %20upgrade%20of%20the%20existing%20fennoskan%201%20. An hvdc converter converts electric power from high voltage alternating current ac to highvoltage direct current hvdc, or vice versa. Application based hvdc transmission types upto 3000 mw hvdc represents the most economical solution to transmit electrical energy over distances greater than approx. Hvdc transformers are either built as singlephase or three phase units as per our requirement. As all generating stations are generating power in ac, we are in need to convert this ac to hvdc. Abb hvdc transformers are at the heart of these systems.
Manufacturers can standardize their product portfolios utilities can have the same equipment for several converter stations same voltage level increased insulation margins for e. Abb library is a web tool for searching for documents related to abb products and services. Abb designed, manufactured and tested the worlds largest hvdc converter transformers for the project. Principlesof hvdc controls convertercontrol functions, dc voltagecontrol 1. Abbs first 800 kv hvdc transformer successfully tested worlds highestvoltage power link with record capacity of 6. In total, about,000 mw hvdc transmission capacity is installed in more than 140 projects worldwide. A remarkable journey transportation of the worlds largest. At present there are more than 100 systems in operation transmitting more than 100 000 mw of power. 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 transformers are used for selfcommutated voltagesourced converters. For longdistance transmission, hvdc systems may be less expensive and suffer lower electrical losses. 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. Application based hvdc transmission types hvdc is an alternative for submarine transmission. Pros and cons with standard insulation levels for hvdc pros. Tapping on hvdc lines using dc transformers sciencedirect.
Reduced emission painting for transformers brochure english pdf brochure. Transformers for hvdc applications document number. 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. Markus pettersson, september 22, 2016 plnabb power. High voltage direct current hvdc transmission finally proved to be technically feasible. Hvdc highvoltage direct current is a highly efficient alternative for transmitting large amounts of electricity over long distances and for special purpose applications. Hvdc converter transformers guidelines for conducting. 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. Economical even for shorter distances such as a few 10kmmiles 23. For long distance transmission of power, hvdc transmissions are more economical than ac. It interconnects the networks that have different frequencies and characteristics.
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 transformers used before the rectification of ac in hvdc system are called as converter transformers. 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. 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. 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. 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. Design considerations of ultra high voltage dc system siemens ag. 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. 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. Abbs hvdc transformer and highvoltage technology will integrate largescale renewables in china. Pdf 800 kv ultra hvdc transformer a new dimension of dc. Abb has participated in the delivery of more than half of the worlds around 170 hvdc links. Abb has delivered more than 75 of these projects with a total transmission capacity of almost 60,000 mw. Hvdc converters capable of converting up to two gigawatts gw and with voltage ratings of.
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. Transformer saturation occurs due to voltage recovery after a. Markus pettersson, september 22, 2016 plnabb power grids. 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. In addition to the converter, the station usually contains. Inverter ud control no change in dc voltage, but change in dc current. The light signals further converted into electrical signals using gate drive amplifiers with pulse transformers. Abb successfully developed and tested 1,100 kv converter transformer technology breaking the record for the highest dc voltage levels ever. Mainly due to the extra conversion equipment and maintenance difficulty.
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. The hvdc system is less expensive and has minimum losses. Applications for high voltage direct current hvdc transmission technologies april 22, 20 nreca conference center. 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. Large hvdc transmission schemes having power transmission capacities of.
Their main application is to transfer power between an ac system and the dc transmission network. High voltage direct current hvdctransmission systems. Power transformers hvdc transformers building trust through a. 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. Plains and eastern hvdc clean line energy partners report r8.