Also, tools for the system programming and supervision are. Pdf bulk power transmission at extra high voltages, a. Environmental characteristics of hvdc overhead transmission lines prof. Not many studies have been done of the health of people living near dc power lines. 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. Increasing the capacity of an existing power grid in situations where additional wires are difficult or expensive to install.
Hvdc transmission a highvoltage direct current hvdc electric power transmission system uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current ac systems the longest hvdc link in the world is currently the xiangjiaba shanghai 2,071 km hvdc allows power transmission between. A protection system for high voltage direct current, hvdc, transmission lines is provided. Hvdc projects for longdistance transmission have two or rarely, more converter stations and a transmission line interconnecting them. This course focuses upon hvdc transmission systems with high ratings, i. Assuming that the end voltages are regulated the power handling capacity of an ehv line, p depends mainly on its length and conductors are chosen to carry this load. As a result, these technologies have limited capability to respond to.
Hvdc network dc fault ridethrough capability is achieved by stopping grid contribution to the fault current, and minimization of the transient component due to discharge of the dc side capacitors. The resulting greater capacity of hvdc lines also means that a single hvdc transmission line can provide as much power as an hvac line of much higher voltage or even of multiple hvac lines. Ability to handle longer periods of overload operations. High voltage direct current hvdctransmission systems. The dc transmission requires conversion at two ends, from ac to dc at the sending end and dc to ac at the receiving end. High voltage direct current hvdc systems enable utilities to move more power further, interconnect grids, integrate renewables, and improve network performance. Hvdc can carry more power for a given size of conductor improved transient stability dynamic damping of the electric system oscillations require less space compared to ac for same voltage rating and size ground can be used as a return conductor no charging current hvdc transmission limits short circuit currents. The level of space charge from hvdc lines is changeable and difficult to predict, as it is. High voltage direct current hvdc power systems use d.
An innovation breakthrough for reliable hvdc grids pdf, abb grid systems. Mainly due to the extra conversion equipment and maintenance difficulty. Theoretical maximum limits on powerhandling capacity of. Generally overhead lines are used for interconnection, but an important class of hvdc projects use submarine power cables. In 1882, a 50kmlong 2kv dc transmission line was built between miesbach and munich in germany. The hvdc high voltage direct current transmission system, although in use since about half a century, is gaining new popularity in recent years, as it can allow to transmit very large amounts of. When and how it is used in transmission electricity is typically transferred between various regions of the country over transmission lines via alternating current ac. Hvdc power supplies are suitable for quick charging of large capacitor banks e. It interconnects the networks that have different frequencies and characteristics. Abb has participated in the delivery of more than half of the worlds around 170 hvdc links. Since the 60s, facts flexible ac transmission systems and hvdc high voltage direct current transmission have developed into a mature technology with high power ratings. Analysis and control of hvdc transmission power system.
During an outage of one pole, the other could be operated continuously with ground return. This document gives an overview of the hvdc protection system. Power handling capacity transfer capability of ehv transmission line solely depends on the current carrying capacity of conductor used in ehv line. Pdf analysis and control of hvdc transmission power system. Koshcheev stpetersburg, high voltage direct current power transmission research institute prepared for the third workshop on power grid interconnection in northeast asia, vladivostok, russia, september 30 october 3, 2003 paper prepared may, 2003 1. Power engineers can help you assess the benefits of using hvdc and facts technology for your project. Karlecik, process and device for regulating n power converter stations of a. But there are some direct current dc power lines, which produce dc or static emfs. As the voltage changes can be sudden, it is obvious that manual control of converter. Converter interactions in vscbased hvdc systems georgios stamatiou. Nevertheless, hvdc grids are more complex than pointtopoint links. In the case of an ac cable, power transmission is limited by the length of the cable due to the capacitive reactive current component.
That is equal to approximately 12 large power plants or close to 2,000 largescale wind turbines. Other lines have also been studied with a view to conversion. Lowering the cost of power transmission via hvdc has been suggested as an option to reduce and stabilize the. Accordingly, the fault protection of these hvdc grids is a.
Hvdc traditionally has been used to transfer large amounts of power over long distances. The highest dc breaking capability is required during dc line faults in the asymmetric and symmetric monopole. Hvdc converter stations do cost more than the ac terminal stations, so a certain distance is required in order for an hvdc system to make economic sense. Vschvdc for industrial power systems cuiqing du division of electric power engineering department of energy and environment chalmers university of technology abstract the recent developments in semiconductors and control equipment have made the voltage source converter based high voltage direct current vschvdc feasible. And the effective dc voltage in bipolar dc is double in the way i think you described. The power carrying capability of an ac line is inversely proportional to. Hvdc transmission becomes the only feasible option for connection of a wind farm when the distance exceeds 100150km 1. But for traditional hvdc the reactive power cannot be controlled independently of. For long distance and high power transmission, high voltage direct current hvdc transmission is a. General considerations, power handling capabilities of hvdc lines, basic conversion principles, static converter configuration.
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. A highvoltage, direct current hvdc electric power transmission system uses direct current for. You need experts who know how to make that future work for you. Power limitations of the hvdc transmission power system. Different types of hvdc links in the previous topic, we learn about the hvdc transmission, which is economical for long distance power transmission, and for the interconnection of two or more networks that has different frequencies or voltages. High voltage direct current hvdc systems grid solutions.
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. Modular multilevel converters for hvdc power stations tel. This is a list of notable highvoltage directcurrent power transmission projects. The maximum power handling capability of a transmission line is a function of the square of its voltage. A cookie is a type of message sent from a website and stored in a users web browser while a user is browsing a website. A cost effective hybrid hvdc transmission system with high performance in dc line fault handling english pdf article. However, insulationrelated thermal problems pose a limitation on the power capability of hvdc cables. For transmitting bulk power through long overhead lines. Pdf high voltage direct current hvdc technology has been widely recognized. Bulk power transmission at extra high voltages, a comparison between transmission lines for hvdc at voltages above 600 kv dc and 800 kv ac. With development in hvdc technology, liberalization of electricity industry. Electric power transmission is the epergne of any power system.
The student learns production and control of hvdc and reduction of harmonics. The features of vsc hvdc systems make them suitable for implementing hvdc grids. Power engineering guide digital asset management siemens. Assessing the cost reflectivity of alternative tnuos. Nov 27, 2011 millions poured into high voltage direct current power lines. Control and planning of multiterminal hvdc transmission systems.
Hvdc and dc 12v ites our hvdc power system reduces acdc conversions between grid and ite. A less common form of transmission is high voltage direct current hvdc. Hvdc transmission is economical as compared with ac transmission for distances exceeding 600 km. In the context of project transmit, rwe npower commissioned. In this presentation, 10 most powerful hvdc high voltage direct current transmission lines constructed in the world, sorted respectively with consideration of power rated of the lines. Bert yes, for similar power handling, hvdc allows smaller conductors for a number of reasons. Hvdc systems utilize power electronics technology to convert ac and dc voltage, and are ideal for supporting existing systems or building new power highways. Converter faults, over current protection valve group, and dc line protection.
An example is the 1,100 kv changjiguquan ultra high voltage direct current uhvdc project in china. Hvdc disadvantages hvdc is generally less reliable and has lower availability than hvac. Jianping wang, bertil berggren, kerstin linden, abb ab sweden. The main characteristics of the voltage sourced converters are a compact design, fourquadrant operation capability and high losses. This is probably because there has not been any strong driver to do this sort of study.
This is a list of notable highvoltage direct current power transmission projects. Cigre and trends in power electronics for the grid bjarne andersen chairman of cigre study committee b4 hvdc and power electronics elecrama, bengaluru, january 2014. Hvdc care service agreements english pdf leaflet hvdc care spare parts management english pdf leaflet. Fresh hvdc xechno power ac dc 340v dc 12v central redundant power supply. Hvdc light was launched in 1997 and is an adaptation of classic hvdc. A hybrid dc circuit breaker with faultcurrentlimiting. Woodford manitoba hvdc research centre 4001619 pembina highway winnipeg, manitoba, r3t 3y6 canada 18 march 1998introductionelectric power transmission was originally developed with direct current. Highvolts hvdc power supplies usually feature a voltagedoubling circuit see fig.
Highvoltage direct current and facts technology are shaping the grid of the future. A backtoback station has no transmission line and connects two ac grids. This paper focuses upon hvdc transmission systems with high ratings, i. Increase in transmission capacity by conversion of. Ensuring that electricity demand can be met ratio between nominal transmission capacity of interconnectors and peak load. The author presents a viable theoretical development, a logical. The present number of links based on this technology is around 120. The most significant advantage of the bipolar link is that if any of their links stop operating, the link is converted into monopolar mode because of the ground return system.
Transfer capability refers to the amount of electric power that can be passed through a transmission network from one place to another. This paper focuses on studying the impact of hvdc system on the power system stability and this accomplished based on applying location. The effects that this mutual inductance has on the hvdc system is mostly going to appear during a dc line fault in one of the poles, since at that moment the current flow in the two poles are very different. The first known example is the ultranet project in germany where a 400 kv ac line will be converted. 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. Based on the development and research results combined with the service experience a new type test philosophy including insulation system tests was developed. Recently, the application of high voltage direct current hvdc technology in the electrical network become more popular due to their advantages comparing with high voltage alternating current hvac system. The transient phenomena of dc fault currents and dc voltages. At that time, conversion between reasonable consumer voltages and. Once the construction is completed in 2019, it will carry more than 12,000 mw of power in one set of power towers. It is used to transmit electricity in lower power ranges from under 100 to 1,200 mw over short and medium long distances. This paper describes the basic requirements of a line protection system in a vsc based mtdc network such as speed, selectivity, sensitivity and security, etc. Ac to hvdc conversions to enhance the power transmission capacity of existing rights of way are ongoing.
The half of the system continues supplies the power. Dc protections ac protections apparatus protective relays common features of the protection philosophy, the protective functions and the fault clearing actions are given. Hvdc has many advantages over ac, such as enhanced power transmission capacity up to the thermal limit 1, low losses, ease of flexibility and controllability both of which help counteract any disruption arising from the connection of renewables, less demanding right of way requirements, etc. What is power handling capacity of ehv transmission line. Abstract smart grid is much more than it and smart meters. Pdf applications of embedded hvdc in power system transmission. At present, the protection methods for the dc line in vsc hvdc grid are mainly borrowed from the line protection in. Dc power transmission an overview sciencedirect topics. Hvdc a key solution in the future transmission system. Long distance hvdc applications using overhead lines are found around the world, in the usa, canada, brazil, china and india. This paper presents a design of converter controllers and filters of line commutated converter high voltage direct current lcc hvdc power transmission system to increase loadability.
Assessing the impacts of increasing penetration of hvdc lines on power system reliability. What is hvdc high voltage direct current transmission. Studies show that it is advantageous to consider dc lines when the transmission distance is 500km or more saadat, 1999. The operating range of the ideal converter theory from 0. Hvdc projects for longdistance transmission have two converter stations and a transmission line interconnecting them. Multiterminal dc system line protection requirement and. Hvdc high voltage direct current lcc line commutated converter lhp left hand of the splane mmc modular multilevel converter. I think in the event of a failure some bipolar dc systems temporarily halve the total voltage, and use earth as a conductor. The maximum power handling capability of a transmission line is inversely proportional to its series reactance some very long lines include series capacitors to reduce the total series reactance. Transient behaviour of vschvdc links with dc breakers. The upfc is a versatile controller which can be used to control active and reactive power flows in a transmission line.
Unit i general considerations, power handling capabilities of hvdc lines, basic conversion principles, static converter configuration. Use of facts and hvdc for power system interconnection and. The increasing demand for hvdc technology requires the adaptation of gas insulated switchgear gis. Hvdc power supplies are designed for shortterm operation. Over voltages due to disturbances on dc side, over voltages due to dc and ac side line faults converter faults and protection in hvdc systems. Hvdc technology is a high power electronics technology used in electric power systems to transfer bulk power over long distances. They use overhead lines, or underseaunderground cables, or a combination of cables and lines. In the multiterminal vsc hvdc grid, the protection for the transmission line should identify the fault line reliably and quickly. The protection system includes a direct current, dc, bus, a device configured to connect an hvdc transmission line to the bus, at least one dc circuit breaker arranged for disconnecting the transmission line from the bus upon reception of a trip signal, current and voltage sensors, an inductor arranged. Vsc hvdc technology was developed during the 1990s, and the first commercial. The vsc hvdc technology, reaching 500 kv today, addresses a number of shortcomings in the classic line commutated thyristor hvdc converters by offering an independent reactive power control, black start capability, usage of extruded polymer cables, smaller station footprint, and the use of standard transformers 88,89. Hvdc vsc evolution april 18, 2017 slide 34 threephase, twolevel voltagesource converter for hvdc threephase, threelevel, diodeclamped voltagesource converter for hvdc the very first vschvdc scheme installed the hellsjon experimental link commissioned in sweden in 1997 until 2012, most of the vsc hvdc systems built were. Convert from ac to hvdc for higher power transmission.
Transient behaviour of vsc hvdc links with dc breakers under faults tim augustin, ilka jahn, staffan norrga and hanspeter nee. Therefore hvdc networks that use converter stations with dc fault reversed. Hvdc circuit breakers are difficult some mechanism must be included in. Transmission 3 1 4 4 unit 1 general considerations, power handling capabilities of hvdc lines, basic conversion principles, static converter configuration. Siemens is offering voltage sourced converters for hvdc applications with ratings up to 250 mw under the trade name hvdc plus power link universal systems. 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.
For a pole outage, in case longterm ground current flow is undesirable, the bipolar system could be operated. In the beginning all hvdc schemes used mercury arc valves, invariably single. A smartgrid is an electricity network that can intelligently integrate the actions of all users connected to it generators, consumers and those that do both in order to efficiently deliver. For connecting two networks or system, various types of hvdc links are used. Power improvement of transmission line using high voltage. The idea for hvdc lines started to gain traction two years ago, when the fukushima nuclear accident in japan led german chancellor angela merkel to shut down 8 of her countrys 17 nuclear. It is well known that highvoltage direct current hvdc cables do not have such limitations. Smallscale high voltage direct current, hvdc phase. It is used to transmit electricity in lower power ranges from under 100 to 1,200 mw over short and. Us20088802a1 fault protection of hvdc transmission. Acs8801604 dcdc converter modules operation principle and hardware, moving and unpacking the ddc module, cabinet construction of acs8801604, mechanical installation instructions, guidelines for planning electrical installation, electrical installation, installation checklist, startup, maintenance, ordering information, technical data, control unit, dimension drawings, example circuit diagrams. Vschvdc has black start capability, which means that it can build up. A live blackstart capability test of a voltage source hvdc converter english pdf article. Hvdc transmission for renewable energy integration.
Transmission ratings of 3 gw over large distances with just one bipolar dc transmission system are state of the art in many grids today. Abb and siemens are fierce rivals in hvdc know how, with each regularly leapfrogging the other in terms of higher voltages, power. Tapping ovhd hvdc with large vsc converters hvdc tap reverse power by polarity reversal electronic clearing of dc line faults fast isolation of faulty converters reactive power constraints momentary interruption due to cf at tap limitations on tap rating, location and recovery rate due to stability hvdc light tap polarity reversal if main link is bidirectional. Abb and siemens in hvdc power race financial times. In every case each wind turbine needs a controller. Such types of links are commonly used in the hvdc systems. For the above mentioned conventional applications, hvdc transmission is an economical and ecofriendly option. Advantages of hvdc comparison of capital co st for hvdc and hvac distance acwithoutcompensation hvdc cost breakeven distance 6 advantages of hvdc typical charging currents for land cables ac cables are limited in length due to the charging current, hvdc cables have no length limitation cross section mm2 current rating a charging current akm.