Estlink hvdc light transmission system, 350 mw 150 kv,including 105 km cables. Pacific intertie in usa and cahorabassa between mozambique and south africa. Harmonic distortion of lcchvdc and vschvdc link in eskom. Caborabassa also spelled cahora bassa is the name for an hvdc power transmission system between the cahora bassa hydroelectric generation station in mozambique, and johannesburg, south africa. Cahora bassa hvdc line emergency restoration ee publishers. Pollution performance of hvdc sir insulators at extra heavy. In particular, to allow electric energy to be transmitted from the power source to the load center, alternating current must first be converted into direct current. Insitu monitoring of leakage current on composite and. The system was built between 1974 and 1979 and can transmit 1920 megawatts at a voltage level of 533 kilo volts dc and. There are also hvac lines supplying cahora bassa power to parts of mozambique and to zimbabwe. Cahora bassa rehabilitation 1975 1998 guizhouguangdong 2004 gezhoubashanghai 1989 basslink. The diagram below illustrates these three levels o f institutional.
North bank extension to cahora bassa additional 1,245 mw that could provide least cost power for the country and the region. The application of dc power transmission entails conversion of alternating current to direct current and vice versa. Apollo is the inverter end of the cahora bassa hvdc scheme. Basic concept operation and control of hvdc transmission. The results have shown that the electrical parameters i. An investigation into the effect of shattered glass discs on.
Insitu monitoring of leakage current on composite and glass. This contract, considered one of the biggest projects in the world, besides the usual construction activities, included also those of deforestation and demining of the land for a good part of the lines. Power flow studies in hvac and hvdc transmission lines. Cahora bassa hvdc line emergency restoration by mike rycroft, features editor, ee publishers during the recent floods in mozambique a section of the cahora bassa hvdc line was damaged. Southern african governments were also involved in an agreement stating that portugal would build and operate a hydroelectric generating station at cahora bassa together with the highvoltage direct current hvdc transmission. An investigation into the effect of shattered glass discs on insulation strength under hvdc voltage stress article in ieee transactions on dielectrics and electrical insulation 234. An electrode line is used in some highvoltage directcurrent hvdc power transmission systems which use the ground or sea as the return path for electric current.
Cabora bassa also spelled cahora bassa is the name for an hvdc power transmission system between the cahora bassa hydroelectric generation station in mozambique, and johannesburg, south africa. It enables the connection of nonsynchronous ac systems and its losses are inferior over long distances. An overview article pdf available in ieee transactions on power electronics 243. The cahora bassa hvdc transmission system is an important source of imported power for the south african grid. The land coverage and the associated rightofway cost for an hvdc overhead transmission line is not as high as that of an ac line.
An hvdc transmission system is basically environmentfriendly because improved energy transmission possibilities contribute to a more efficient utilization of existing power plants. Hcb currently operates under a concession agreement granted by the state of mozambique, managing and operating the assets that form part of the cahora bassa scheme. Jan 30, 2020 cahora bassa hvdc wikipedia transmission line towers may be designed to carry two conductors, even if only one is used initially for the monopole transmission system. The principle of simplicity and flexibility were used in the design of. Abstracthigh voltage transmission line design requires careful insulator selection to ensure good operational performance.
Hvdc and flexible ac transmission subcommittee of the. Abb library is a web tool for searching for documents related to abb products and services. Hvdc transmission lines, overhead transmission line, mozambique. Moreover, the conversion of existing hvac overhead lines to hvdc has started to be implemented all over the world, to avoid building new right of ways. Jan 18, 2016 epri helps industry navigate new opportunities with highvoltage direct current transmission. This reliance grew in the 1980s with the construction of bipole ii and is. Power transmission to south africa was interrupted during the mozambican civil war but resumed during the mid1990s. Dc and ac conductors, either as overhead transmission lines or submarine cables can have lower losses but at higher expense since the. Cahora bassa the cahora bassa hvdc transmission system is an important source of imported power for the south african grid. Transmission and distribution development of standing waves. However, because of its relatively new application in hvdc schemes, little has been published relating to operational data on typical leakage current magnitudes, waveforms and consequential effects thereof. Cahora bassa welsh 1995 2006 2000 cometa 2012 inter island connector pole 3 2014 tianshengqiaoguangzhou. Control measures to ensure dynamic stability of the cahora bassa scheme and the parallel.
Development of standing waves on long distance hvdc transmission lines by b r duncan and j m van coller, university of the witwatersrand the cahora bassa hvdc scheme in southern africa can transmit 1920 mw from mozambique to south africa. Thyristor valves are used, which unlike other hvdc schemes. An investigation into the effect of shattered glass discs on insulation strength under hvdc voltage stress article in ieee transactions on dielectrics and. Cahora bassa dam supplies power primarily to south africa over an 870mile 1,400kilometre long, dual 530kilowatt transmission line and also to maputo, tete, and the moatize coal mines near the town of tete. Ac and dc power transmission, sixth international conference on conf. Hvdc transmission is a key enabler of the emerging single energy market. Many longdistance hvdc systems use sea or ground return for the dc neutral current since this is considerably cheaper than providing a dedicated metallic return conductor on an overhead wire or cable. Figure 1 basic hvdc transmission system model for simulation the block diagram for basic hvdc transmission system model for simulation is shown in fig. Cahora bassa apollo connecting remote generation the cahora bassa hvdc transmission system is an important source of imported power for the south african grid.
Apollo hvdc converter station background of apollo grid. Hcb, eskom work on cahora bassa line refurb plan after. Cahora bassa hvdc transmission system is between the songo converter station. Cahora bassa is a 2,075 mw hydropower project on the zambezi river in mozambique, supplying power primarily to south africa via 1,400 km of highvoltage direct current hvdc transmission lines. At that time, the cahora bassa had the highest transmission. Upgrade of the apollo hvdc converter station abb group. Cahora bassa hvdc transmission system is between the songo converter station mozambique hcb and apollo converter station south africa eskom. This had a huge impact on the transfer of power between mozambique and south africa with one of the 533 kv dc lines out of service.
Dc power transmission an overview sciencedirect topics. Cahora bassa, a thyristors based hvdc link transmits 1,920 mw of power from hydropower plant located in zambezi river, north of mozambique to johannesburg, south africa. The link provides 1,920 mw of power transmission capacity from a hydropower plant on the zambezi river in northern mozambique, and was put into service in three stages, from 1977 to 1979. However, to improve its resilience, coverage andor to be able to export more power, the transmission system also needs. Aug 20, 2014 however, because of its relatively new application in hvdc schemes, little has been published relating to operational data on typical leakage current magnitudes, waveforms and consequential effects thereof. Peter kohnstam, 22 april 20, united states department of. At songo converter station, this power is converted to dc and sent to apollo converter station.
Figure 5 shows an example of the electrical equipment required for a d. Hvdc from reference 3, losses are lower is not correct. The apollo songo hvdc scheme receives power generated at cahora bassa hydro power station. Following a refurbishment exercise, 2 the scheme was put back into commercial operation in october in the original installation they were oil filled for both cooling and. Composite core conductor accc conductors from ctcarb to replace the. Cahora bassa dam and hydroelectric facility, mozambique. Approximately 2000 characteristics of an hvdc mw are generated by five turbinegenerator sets transnission syster1 at the cahora bassa hydro station in mozambique, fed to the songo terminal where the power transmission by hvdc is relatively bulk of the infeed is rectified for simple the power transmitted from the transmission purposes. Cahora bassa hcb in mozambique and eskom in south africa. Microsoft access 2002 relational database management system was chosen for this work. It was shown that development of plan 3 with the proposed hydro and thermal plants would reduce power. Hvac 3phase lower transmission loss because of no reactive loss lower insulationclearance of conductor dc voltage is about 71%. The system comprises two parallel monopolar lines across a 1,400km long route.
Epri helps industry navigate new opportunities with highvoltage direct current transmission. Pdf control measures to ensure dynamic stability of the cahora. White paper developments in uhvdc and uhvac transmission. For practical reasons a database was developed to hold and analyse the performance data. This meant that transformer manufacturers where faced with a number of new technical challenges mainly in the field of dielectrics, since the increase in dctransmission voltage was directly reflected on the transformer insulation. Southern african governments were also involved in an agreement stating that portugal would build and operate a hydroelectric generating station at cahora bassa together with the highvoltage direct current hvdc transmission system required to. Sresa of a regional transmission development in mozambique. In addition to significantly lowering electrical losses over long distances, hvdc transmission is also very stable and easily controlled.
This paper reports on the insitu measurements of leakage current lc on composite and glass insulators of the cahora bassa high voltage direct current hvdc transmission line in. An investigation into the effect of shattered glass discs. Hvdc transmission lines, overhead transmission line. Since the construction of the bipole i highvoltage, direct current hvdc transmission line in the 1970s, winnipeg, canada, has relied more than most cities on hvdc technology. Hvdc projects listing prepared for the dc and flexible ac transmission subcommittee of the ieee transmission and distribution committee by the working group on hvdc and facts bibliography and records. The parameter of the hvdc system are given in table i 11, 12.
Caborabassa also spelled cahora bassa is the name for an hvdc power transmission system between the cahora bassa hydroelectric generation station in mozambique, and johannesberg, south africa. Any scalingup of such imports are also likely to involve highvoltage, direct current hvdc schemes, but will incorporate newer, more reliable technology than is. However, to improve its resilience, coverage andor to be able to export more power, the transmission system also needs to be extensively refurbished and expanded. Several major project developments are proposed to be implemented as components of the cesul system. Cahora bassa hvdc wikipedia transmission line towers may be designed to carry two conductors, even if only one is used initially for the monopole transmission system. The aim of this study was to assess the electrical performance of the cahora bassa hvdc scheme. Media in category cahora bassa hvdc the following 3 files are in this category, out of 3 total. Two page brochure describing the cahora bassa apollo upgrade project in south africa. These comprise the dam, the hvdc transmission system and the matambo substation and transmission lines. Any scalingup of such imports are also likely to involve highvoltage, direct current hvdc schemes, but will incorporate newer, more reliable technology than is being used for the cahora bassa.
The cahora bassa system started in the late 1960s as a project of the portuguese in the overseas province of mozambique. Hvdc systems can transmit more electrical power over longer distances than a similar alternating current ac transmission system, which means fewer transmission lines are needed, saving both money and land. The cahora bassa hydroelectric complex has been in operation since 1975 and comprises a variety of engineering infrastructures the hydroelectric power station, the songo converter substation, the hvdc and hvac transmission lines and the matambo substation enabling the production, transmission and commercialisation of energy. Cahora bassa apollo upgrade english pdf brochure the norned hvdc transmission link the longest underwater highvoltage cable in the world english pdf brochure advanced lcc hvdc control with mach3 improved commutation failure prediction, and additional functionality for 800 kv uhvdc english pdf article. Cahora bassa sapei square butte sharyland three gorgeschangzhou caprivi link xiangjiabashanghai apollo upgrade ipp upgrade itaipu north east agra jinping sunan mackinac 58 hvdc classic projects since 1958 14 hvdc upgrades since 1990 19 hvdc light projects since 1997. High voltage direct current transmission peter kohnstam, 22 april 20, united states department of energy. Introduction to the cahorabassa hvdc transmission lines. Cahorabassa previously spelled cabora bassa is an hvdc power transmission system between the cahora bassa hydroelectric generation station at the. Cahora bassa previously spelled cabora bassa is the name for an hvdc power transmission system between the cahora bassa hydroelectric generation station at the cahora bassa dam in mozambique, and johannesburg, south africa. Feasibility of increased power via apollo songo hvdc. In china, the first hvdc transmission scheme known as the gesha scheme has a capacity of 1200 mw which interconnects central china and eastern china. Project for the construction, reconstruction and rehabilitation of two parallel 533 kv hvdc transmission lines named.
The dc line is experiencing numerous insulator flashovers. The level of losses is designed into a transmission system and is regulated by the size of conductor selected. Transmission and distribution cahora bassa hvdc line. This paper reports on the insitu measurements of leakage current lc on composite and glass insulators of the cahora bassa high voltage direct current hvdc transmission line in south africa. The potential of regional power sector integration cahora. This paper reports on the insitu measurements of leakage current lc on composite and glass insulators of the cahora bassa high voltage direct current hvdc transmission line in south africa over a 6 month period. Recent technological development has allowed hvdc transmission to be a viable candidate. Eskom currently operates and maintains the south african sections of the cahora bassa hvdc scheme. In this example, two poles are represented which is the usual case and is known as the bipole configuration. Source of imported power is the cahora bassa hydroelectric generation station at the cahora bassa dam on zambezi river north of mozambique. The projects considered in the sresa are presented intable 1. Manual fault entry screen for reliability analysis.
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