Hvdc transmission lines, overhead transmission line, mozambique. 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 is the inverter end of the cahora bassa hvdc scheme. It enables the connection of nonsynchronous ac systems and its losses are inferior over long distances. Any scalingup of such imports are also likely to involve highvoltage, direct current hvdc schemes, but will incorporate newer, more reliable technology than is. Thyristor valves are used, which unlike other hvdc schemes. The dc line is experiencing numerous insulator flashovers.
The potential of regional power sector integration cahora. 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. Power flow studies in hvac and hvdc transmission lines. The application of dc power transmission entails conversion of alternating current to direct current and vice versa. 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. 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. Jan 18, 2016 epri helps industry navigate new opportunities with highvoltage direct current transmission. White paper developments in uhvdc and uhvac transmission. 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 parameter of the hvdc system are given in table i 11, 12. An overview article pdf available in ieee transactions on power electronics 243.
The level of losses is designed into a transmission system and is regulated by the size of conductor selected. This reliance grew in the 1980s with the construction of bipole ii and is. 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. Pacific intertie in usa and cahorabassa between mozambique and south africa.
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. Cahora bassa dam and hydroelectric facility, mozambique. The projects considered in the sresa are presented intable 1. 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. Insitu monitoring of leakage current on composite and. Control measures to ensure dynamic stability of the cahora bassa scheme and the parallel. 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. An investigation into the effect of shattered glass discs on insulation strength under hvdc voltage stress article in ieee transactions on dielectrics and. An investigation into the effect of shattered glass discs. Cahora bassa hcb in mozambique and eskom in south africa. 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 johannesberg, south africa.
The results have shown that the electrical parameters i. In addition to significantly lowering electrical losses over long distances, hvdc transmission is also very stable and easily controlled. Harmonic distortion of lcchvdc and vschvdc link in eskom. 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. Hvdc from reference 3, losses are lower is not correct. 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. The apollo songo hvdc scheme receives power generated at cahora bassa hydro power station. The cahora bassa system started in the late 1960s as a project of the portuguese in the overseas province of mozambique. Media in category cahora bassa hvdc the following 3 files are in this category, out of 3 total. 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. 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. 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.
Abstracthigh voltage transmission line design requires careful insulator selection to ensure good operational performance. Microsoft access 2002 relational database management system was chosen for this work. Cahora bassa hvdc line emergency restoration ee publishers. Pollution performance of hvdc sir insulators at extra heavy. Ac and dc power transmission, sixth international conference on conf. 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. Several major project developments are proposed to be implemented as components of the cesul system. 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. At that time, the cahora bassa had the highest transmission. Introduction to the cahorabassa hvdc transmission lines.
Transmission and distribution cahora bassa hvdc line. 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. The land coverage and the associated rightofway cost for an hvdc overhead transmission line is not as high as that of an ac line. Peter kohnstam, 22 april 20, united states department of.
Pdf control measures to ensure dynamic stability of the cahora. The aim of this study was to assess the electrical performance of the cahora bassa hvdc scheme. 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. Upgrade of the apollo hvdc converter station abb group. Hcb, eskom work on cahora bassa line refurb plan after. 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. North bank extension to cahora bassa additional 1,245 mw that could provide least cost power for the country and the region. Cahora bassa the cahora bassa hvdc transmission system is an important source of imported power for the south african grid. Estlink hvdc light transmission system, 350 mw 150 kv,including 105 km cables. These comprise the dam, the hvdc transmission system and the matambo substation and transmission lines.
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. Two page brochure describing the cahora bassa apollo upgrade project in south africa. Pollution performance of hvdc sir insulators at extra. Hvdc transmission is a key enabler of the emerging single energy market.
Dc and ac conductors, either as overhead transmission lines or submarine cables can have lower losses but at higher expense since the. Abb library is a web tool for searching for documents related to abb products and services. 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. 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. Manual fault entry screen for reliability analysis. 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. An hvdc transmission system is basically environmentfriendly because improved energy transmission possibilities contribute to a more efficient utilization of existing power plants. Cahora bassa welsh 1995 2006 2000 cometa 2012 inter island connector pole 3 2014 tianshengqiaoguangzhou. Hvdc and flexible ac transmission subcommittee of the. It was shown that development of plan 3 with the proposed hydro and thermal plants would reduce power.
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. Cahorabassa previously spelled cabora bassa is an hvdc power transmission system between the cahora bassa hydroelectric generation station at the. 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. Figure 1 basic hvdc transmission system model for simulation the block diagram for basic hvdc transmission system model for simulation is shown in fig. 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. 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. Epri helps industry navigate new opportunities with highvoltage direct current transmission.
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. 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. 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. Cahora bassa hvdc transmission system is between the songo converter station mozambique hcb and apollo converter station south africa eskom. Transmission and distribution development of standing waves. Hvac 3phase lower transmission loss because of no reactive loss lower insulationclearance of conductor dc voltage is about 71%. There are also hvac lines supplying cahora bassa power to parts of mozambique and to zimbabwe. Recent technological development has allowed hvdc transmission to be a viable candidate. Power transmission to south africa was interrupted during the mozambican civil war but resumed during the mid1990s. In this example, two poles are represented which is the usual case and is known as the bipole configuration.
Insitu monitoring of leakage current on composite and glass. 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. Feasibility of increased power via apollo songo hvdc scheme. 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. Dc power transmission an overview sciencedirect topics.
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. The system comprises two parallel monopolar lines across a 1,400km long route. For practical reasons a database was developed to hold and analyse the performance data. At songo converter station, this power is converted to dc and sent to apollo converter station. Hvdc transmission lines, overhead transmission line. 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. Figure 5 shows an example of the electrical equipment required for a d. 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. Apollo hvdc converter station background of apollo grid.
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. Feasibility of increased power via apollo songo hvdc. However, to improve its resilience, coverage andor to be able to export more power, the transmission system also needs. An investigation into the effect of shattered glass discs on. Eskom currently operates and maintains the south african sections of the cahora bassa hvdc scheme. The principle of simplicity and flexibility were used in the design of. 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. 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. The system was built between 1974 and 1979 and can transmit 1920 megawatts at a voltage level of 533 kilo volts dc and. Project for the construction, reconstruction and rehabilitation of two parallel 533 kv hvdc transmission lines named. Cahora bassa hvdc transmission system is between the songo converter station. High voltage direct current transmission peter kohnstam, 22 april 20, united states department of energy. Sresa of a regional transmission development in mozambique. The diagram below illustrates these three levels o f institutional.
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