Hvdc is used as an alternative to ac for transmitting electrical energy over long distances or between ac power systems of different frequencies. Plnabb power grids workshop abb hvdc converter transformers markus pettersson, september 22, 2016. The most powerful hvdc transformer in the world has recently successfully passed its test phase in nuremberg, germany. Markus pettersson, september 22, 2016 plnabb power. Hvdc power transmission an overview sciencedirect topics. Because of the superposition of the voltage harmonics, the valve voltage wave is more serrated than a pure ac voltage. Hvdc transmission systems unit1 introduction electric power transmission was originally developed with direct current. The control of vschvdc and its use for large industrial. Hvdc transformers transformers siemens siemens global. Study of the stray losses calculation in structural parts for hvdc converter transformers based on the team problem 21 family. Pdf dc transformer for dcdc connection in hvdc network.
The transformers form part of the hvdc transmission link built in the 1970s to transmit electrical power from the hydropower plant over a distance of 1,450 kilometers. One bipolar hvdc transmission system with two conductors, a positive and a negative one is equivalent to a double circuit ac transmission line for the same transmitted power. Sep 28, 2017 good question, let me explain you, being a hvdc engineer. High voltage direct current transmission pdf notes hvdc. Apr 02, 2015 this transformer recycling project was performed as part of the pacfic hvdc intertie upgrade. Insultion provided for converter transformer is very high as it needs to. 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. As the voltage changes can be sudden, it is obvious that manual control of converter. Measurementbased frequencydependent model of a hvdc. The protection of these transformers is therefore essential for the reliable operation of the hvdc link. The recent development in semiconductor and control equipment has made the highvoltage direct current transmission based on voltage sourced converters vsc. The transformers form part of the hvdc transmission link built in the 1970s to transmit electrical power from the hydropower plant over a. In converter transformer primary is not much affected where as secondary is severely affected. What is the difference between a converter transformer.
The operation condition of converter transformers is more complex than that of conventional ac transformers. 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. An excellent agreement between simulation and measurement is achieved. Abstractpower transformers can fail from dielectric stresses caused by. Further easy to comprehend analytical model in universally available software like matlabsimulink can help in fast spread of complex hvdc system knowledge also to those who are responsible for operation and maintenance of these systems thus bringing large benefits. This transformer recycling project was performed as part of the pacfic hvdc intertie upgrade. Hvdc traditionally has been used to transfer large amounts of power over long distances. The worlds first hvdc transformer passes the test for 1,100. The availability of transformers and the development and improvement of induction motors at the beginning of the 20th century, led to the use of ac transmission. Abb hvdc transformers are at the heart of these systems. As a key enabler in the future energy system based on renewables, hvdc. The breakeven distance, depending on specific cases could be between 450 600 km. Markus pettersson, september 22, 2016 plnabb power grids. Pdf 800 kv ultra hvdc transformer a new dimension of dc.
Hvdc highvoltage direct current ppt topics for seminar. Hvdc transformers, transformers, power transformers, hvdc. Hvdc converters capable of converting up to two gigawatts gw and with voltage ratings of up to 1,100. Hvdc transformers are either built as singlephase or three phase units as per our requirement. Generation of hvac transformer with divided secondary winding in metal housing. Pdf 800 kv ultra hvdc transformer a new dimension of.
Hvdc transmission overview 5 core hvdc technologies ac dc hvdc csc indoor outdoor ac filters dc filters thyristor valves converter transformers ac dc hvdc vsc indoor outdoor igbt valves ac hvdc classic current source converters linecommutated thyristor valves requires 50% reactive compensation 35% harmonic filter converter transformers. As a galvanic barrier between ac and dc systems to prevent. The worlds first hvdc transformer passes the test for. Hvdc transformers transformers siemens global website. A large amount of higher harmonics will be generated in the load current when the transformer. Project on transformers pdf project report physics xii transformers free download as pdf file.
Large transformer removal project hvdc station upgrade youtube. Here you can download the free lecture notes of high voltage direct current transmission pdf notes hvdc pdf notes materials with multiple file linksthe high voltage direct current transmission notes pdf hvdc notes pdf. The massive transmission of electricity in the form of dc over long distances by means of submarine cables or overhead transmission line is the high voltage direct current transmission. The development of domestic hvdc transmission system needs the hvdc transformer to perform better. 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 classic converter transformers hvdc converter. It serves as an isolating device between power transformer and dc link. In hvdc plus monopole applications, no dc voltage stresses occurs at the transformer valve terminals. As a result, the insulation system withstands severe stress. For operators, assessing reliability risks is crucial for evaluating the total cost of ownership of an hvdc transformer. Tailoredtofit and delivered fullyassembled, hvdc transformers by siemens enable reliable and. Historically the main use of high voltage direct current hvdc systems has been the bulk transmission of power over long distances and interconnecting neighbouring asynchronous ac systems. Converter transformers operate with high flux power steps in the four steps of the converter per cycle, and so produce more acoustic noise than normal threephase power transformers.
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. This chapter presents the sen transformer st that offers a whole slew of power flow control features, such as independent power flow, voltage, phase angle, impedance, fault current, all in one unit, which uses time. Demand for hvdc transformers has increased as renewable energy sources like offshore wind farm and. Siemens overhauls 15 converter transformers at cahora bassa. Supply of ac voltages into two separate circuits feeding the rectifier bridges with a phase shift of 30 electrical degrees for reduction of low order harmonics esp. The general aspects, including application and build up, of high voltage direct current hvdc power transmission systems and static var compensators svc will be described in this chapter.
Stray loss calculation of hvdc converter transformer. Compared to alternating current, the direct current system is less expensive and loses less energy. This happens because hvac lines are more expensive than hvdc lines. Abb has a deep understanding of the different net system operating conditions. Recently new applications have been found, most prominently the interconnection of large offshore windfarms. Paper presented at 15th international workshop on largescale integration of wind power into power systems as well as on transmission networks for offshore wind power plants, vienna, austria, 1517 nov. Hitachis kokubu factory located in hitachi city, japan is a highly sophisticated research and quality control facility that has been supplying large capacity power transformers to the worldwide market since 1910. Hvdc highvoltage direct current is a highly efficient alternative for transmitting large amounts of electricity over long distances and for special purpose applications. In this way the 5th and 7th harmonic currents through the two transformers are in opposite phase. Hvdc disadvantages hvdc is generally less reliable and has lower availability than hvac. The fundamental stray losses in different currents and the harmonic stray losses of the team problem 21 family members are analyzed to verify the iec method. Charpentier raghuveer sharma abb power systems world bank abb financial services sweden united states sweden synopsis beginning with a brief historical perspective on the development of high voltage direct current hvdc. Hvdc transformers are key components of hvdc stations.
Power transformers hvdc transformers building trust through a. With successful testing of the worlds first hvdc transformer for a transmission voltage of 1,100 kilovolts, we have set a new benchmark in directcurrent transmission, states beatrix natter, ceo of power transformers at siemens energy management. For longdistance transmission, hvdc systems may be less expensive and suffer lower electrical losses. There are power converters with ratings in excess of mw.
Insultion provided for converter transformer is very high as it needs to withstand voltage stress under both ac and dc condition. 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. Sweden united states sweden synopsis beginning with a brief historical perspective on the development of high voltage direct current hvdc transmission systems, this paper presents an overview of the status of hvdc systems in the world today. High voltage direct current transmission open government. 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. To secure reliable and safe service conditions, abb comem operating unit provides a comprehensive range of measurement and safety devices, including the new generation of smart devices and costeffective complete solutions that monitor transformer health and improve safety, reliability and efficiency, while minimizing environmental impact. This effect should be considered in the siting of an hvdc converter station. The functional and performance requirements for the protection and control of hvdc systems are covered. This type of transformer provides the interface between ac grids and high power rectifiers and are used to control the load flow over the dc transmission lines. Highvoltage directcurrent hvdc power transmission is the most powerful application for linecommutated converters that exist today.
High voltage direct current transmission only active power flow is associated with hvdc. High voltage rectifiers semiconductor diode a conducting state. Oct 26, 2015 the stray losses calculation method proposed by the iec 6782 standard is analyzed in this study. Structure of a test transformer with open iron core. 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. Pdf study on harmonic characteristics of single phase three. The worlds largest hvdc converter transformers provided to. What is the difference between a converter transformer used. It is applicable for point to point hvdc links with both current sourced converters csc and voltage sourced converters vsc. It is also used to interconnect separate power systems, where traditional alternating current ac connections cannot be used. Hvdc converter and inverter stations terminate longdistance dc transmission lines or dc sea cables. The conversion from ac to dc and viceversa is done in hvdc converter. It converts direct current to alternating current or the reverse. Abb library is a web tool for searching for documents related to abb products and services.
The transformers offer lower losses, require less maintenance and will extend the lifetime of the hvdc link. Additional protection current transformers at tata steel. Hvdc converter transformers are the heart of hvdc transmission systems. Plnabb power grids workshop abb hvdc converter transformers markus pettersson, september 22, 2016 factory in operation since 1893. Mainly hvdc transformer primary is not much affected where as finds advantages in interconnection of two or more systems secondary is severely affected due. As a key enabler in the future energy system based on renewables, hvdc is truly shaping the grid of the future. In addition to the converter, the station usually contains. Pdf study on harmonic characteristics of single phase. Study of the stray losses calculation in structural parts for. Hvdc can be transmitted through cables both underground and underwater. This type of transmission is preferred over hvac transmission for very long distance when considering the cost, losses and many other. 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. Hvdc converter transformers guidelines for conducting. Today, hitachi has supplied over 6,800 units with power capacity up to 3,000 mva and voltage up to 1,000 kv.
Hvdc is an established technology that has been in. Hence, for given rated transmission power of an hvdc link, the converter transformers and converter valves are required to have as large nominal capacity as possible. Hvdc transmission system converter can be obtained by analytical modelling. The hvdc technology the fundamental process that occurs in an hvdc system is the conversion of electrical current from ac to dc rectifier at the transmitting end, and from dc to ac inverter at the receiving end. Teee is one of the best manufacturer and supplier company of transformers, high current power inductor, coil innovations, hvdc, electrical energy equipment and power substation in virginia, oregon, california, new york. Abb has participated in the delivery of more than half of the worlds around 170 hvdc links. Hvdc transformers are used for selfcommutated voltagesourced converters. Buy ehvac, hvdc transmission and distribution engineering by s. Abstractthe converter transformer is a vital equipment in hvdc transmission system.
Product range of siemens transformers generator and system transformers above 2. Ac transformers as dc voltage is taken mainly by pb. Good question, let me explain you, being a hvdc engineer. Main duct in hvdc transformers require more pb barriers than normal.
Converter transformer an overview sciencedirect topics. 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. Converter transformers are key facilities in hvdc systems. Design of power converters for hvdc applications eep. The voltage harmonics in valve winding of converter transformers are analyzed. The component that enables this conversion process is the thyristor high. The stray losses calculation method proposed by the iec 6782 standard is analyzed in this study. This comprehensive reference guides the reader through all hvdc technologies, including lcc line commutated converter, 2level vsc and vsc hvdc based on modular multilevel converters mmc for an indepth understanding of converters, system. Mainly due to the extra conversion equipment and maintenance difficulty. Hvdc circuit breakers are difficult some mechanism must be included in the circuit breaker to force current to zero. Dc transformer for dcdc connection in hvdc network. Transformer, inductor, electrical equipment, power substation. Hvdc converter transformers power transformers abb. Download ehvac, hvdc transmission and distribution.
The transformer will enable lowloss highvoltage directcurrent hvdc power transmission over a record distance of 3,284 kilometers with a transmission capacity of twelve gigawatts. Including failure rates fr and meantimebetweenfailure rates mtbf of a siemens hvdc transformer in purchase considerations lowers your risk potential and ensures savings over the entire transformer lifecycle. Siemens overhauls 15 converter transformers at cahora. 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. Applications for high voltage direct current hvdc transmission technologies april 22, 20 nreca conference center.
The hvdc and svc techniques have very much in common since thyristors are used as switching elements in both cases. Download pdf download citation view references email request permissions export to collabratec alerts abstract. High voltage direct current transmission notes pdf hvdc. An hvdc converter converts electric power from high voltage alternating current ac to highvoltage direct current hvdc, or vice versa. Large transformer removal project hvdc station upgrade. Hvdc transformers are together with thyristor valves the fundamental components in any lcctype hvdc converter. Power transformers hvdc transformers building trust.