Практика Shadowing: 17E058 - Back to Back Stations - Изучайте разговорный английский по видео
Создание урока...
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Hello everyone, I am Monika.
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I am here to present back -to -back stations.
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Let's see.
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What is back -to -back?
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Generally, in electronics and power electronics, if two bipolar components are connected in series with opposite polarity, then this pair is known as back -to -back system.
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As same as in electrical, rectifiers and inverters are identical
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and connected in series is known as back -to -back system from this diagram here rectifier
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and the inverter are connected in series via a hvdc link
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and it is also a hvdc back -to -back link a back -to -back hvdc link the hvdc system
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which transfers energy between two ac buses at the same location is called as back -to -back system
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or an hvdc coupling system in other words the converters
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and rectifiers are installed and operates on high voltage DC in the same stations.
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Hence there is no DC transmission line.
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So it reduces the overall conversion cost and improve the reliability of the DC system.
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Such type of system is designed for bipolar operation.
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This picture shows the bipolar link of a back -to -back link.
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A bipolar link has two conductors.
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One is positive and the other one is negative.
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This link has two converter stations at each end.
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The midpoint of the converter station is connected to the air through the electrodes.
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Next, we are going to see about the construction of back -to -back HPDC link.
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The main components are converter station, converter unit, converter vaults, converter transformer,
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filters, high frequency filter, reactive power source, smoothening reactors and then system port.
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What do you mean by converter walls?
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There are two types of converter walls.
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One is the sending end converter and then receiving end converter.
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The sending end converter act as a rectifier which converts AC into DC.
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The receiving end converter act as a inverter which converts DC into AC.
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What are converter transformers?
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These are transformers
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which are used before the rectification of ac in the hvdc system filters filters may be ac
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or dc what is the use of high frequency filters these
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are provided to suppress the high frequency currents what do you mean by smoothening reactors smoothening reactors are those
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which is used on the dc side to smoothen the dc current as well as the production purposes
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This shows the simple block diagram of back -to -back HPDC link.
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From the system 1, AC current is converted into DC by means of rectifier
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and current DC is supplied via DC link
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and it is converted back again to AC by means of inverter and then distributed to the different grids.
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It shows the simple block diagram.
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Working principle of back -to -back link.
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Two independent neighboring transmission systems with incompatible electrical parameters such as frequency
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or voltage level or short -circuit power level are connected via a DC link.
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The basic principle operation of HPDC linking system is based on the conversion of AC to DC
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and vice versa by means of converter volts power from two
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or more system is first converted into dc by means of power rectifier system
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and then summed up after summing of the resultant power is
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again converted into ac with the help of power inverter
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and then supplied to different grids the process involved in here is simple only by theoretical
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but in practical it is very much complex as it involves high voltages
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and power semiconductor devices what are the needs for back -to -back stations we all know
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that high voltage ac is used to transmit the electrical power for reducing power transmission losses
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in a transmission system different grids are interconnected but sometime it might happen
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that one or more grids or power systems may not be in synchronization with other grids
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or there exist a weak link between different power systems due
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to various factors to overcome these problems hvdc back -to -back system is created it also can be used
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when two asynchronous ac system need to be interconnected for a bulk power transmission
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and also for the stabilization processes these are the some examples of back -to -back stations mcnell hvdc back -to -back station,
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HVDC back -to -back link commissioned between India and Bangladesh, Chandrapur HVDC back -to -back station, Vaisak back -to -back station, Windyashal back -to -back station.
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We will see them one by one in the following slides.
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McNeil HVDC Back -to -Back Station A back -to -back station
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is a series of HVDC interconnectors between the unsynchronized eastern and western AC systems of United States and Canada.
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It connects the power grids of Canadian provinces at Alberta and Saskatchewan.
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The station was built by Geck -Alstom,
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was commissioned in 1989, with the power capacity about 150 megawatt at a DC voltage of 42 kilovolt.
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This picture shows the back -to -back station at Alberta.
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Mechanical station was notable for operating with low short -circuit ratio.
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What do you mean by short -circuit ratio?
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Short -circuit ratio is a measure of how strong or weak the connected AC system is.
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Most of the HVDC schemes uses line commutated converters with SCR about 3,
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but McNeill's scheme was designed to operate with an effective SCR which is even less than 1 .0 on the SASCAT7 side.
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So hence it was the only SCR with the lowest value
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ever achieved with the line commutated hvdc converter it is also
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considered as the first hvdc station to use three phase four winding converter transformer the transformer
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which are connected at the 138 glow volt at alberta side
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and 230 glow volt on the saskatchi one side the number of poles used in this link is about only one Next,
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we are going to see about Indo -Bangladesh link, a SVDC back -to -back link commissioned between India and Bangladesh.
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This Indo -Bangladesh link was commissioned by Siemens.
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Here, two back -to -back links are installed.
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The block one is in operation since 2013 with a capacity of 500 megawatts.
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Siemens recently announced that in June 2020, it fully commissioned the second block of hvdc back -to -back
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line in barhamara at bangladesh to connect the electricity supply network to india
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and bangladesh with the transmission capacity of 500 megawatts hence a total capacity is up to 1000 megawatt
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which is the highest reliable power capacity in bangladesh Siemens is a world leader in HVDC technology,
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which has installed more than 55 projects worldwide with an overall capacity of 94 GW.
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This picture shows the back -to -back stations at Biramara at Bangladesh.
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This is the map which shows the back -to -back HVDC link between India and Bangladesh.
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Here, from Biramara, at the western border of Bangladesh,
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a 230 kV grid of the country will be connected via substation and OH lines to India's 400 kV grid,
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which is located at Baharampur.
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Next, we are going to see about Chandrapur back -to -back HVDC station.
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It is a back -to -back HVDC connection between western and southern regions in India located close to the city of Chandrapur.
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Its main purpose is to export power from the Chandrapur Super Thermal Power Station to the southern regions of Indian National Grid.
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This picture shows the power station at Chandrapur.
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It was owned by Power Grid Corporation of India and the installer for the substation is Gek Alstom and commissioned in 1997.
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7 with a power capacity of 500 megawatts at a dc
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voltage of 205 kilo volt at each pole next we are
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going to see about why is a back -to -back hvdc
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station why is a back -to -back hvdc station is a back -to -back hvdc station connection between the eastern
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and southern regions in india located close to the city of Viswagapatnam in the state of Andhra Pradesh.
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It was owned by Power Grid Corporation of India.
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It has two substations namely VISAG -1
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and VISAG -2 commissioned in 1999 by Alstom
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and the latter in 2005 by ABB
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which has a power capacity of 500 megawatts
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and a DC voltage of 205 kilovolt at ysac 1 and 176 kilovolt at ysac 2.
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It consists of two independent poles.
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The station is no longer required for its original purpose of linking eastern and southern grids,
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although it can be still used as an embedded power flow device to help control power flow within the AC system.
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Next, we can see recent developments.
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Power Grid Corporation of India has chosen Siemens to upgrade India's oldest HVDC link,
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which is the India's oldest HPDC link.
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Any guess, Vintiachal back -to -back HPDC link is the India's oldest link.
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And Siemens has been chosen by Power Grid of India to modernize it.
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Next, we can see some of the advantages of back -to -back HPDC link.
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Power can be upgraded to desired frequency then two asynchronous systems can be joined successfully without loss of stability
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stability of the system is increased as well as power flow can be maintained within the limits
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more active power can be added where the ac system is
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already at the limit of short circuit capability then it also
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helps in the stabilization of weak ac signals weak ac links thank you
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Лексика и советы по произношению к этому уроку
Этот урок разговорной практики построен на видео «17E058 - Back to Back Stations». Чаще всего повторяются слова: link, station, hvdc, converter, grid. В этом видео 119 предложений и 1512 слов для шедоуинга. Речь длится 11:21. Говорящий держит ровный темп — около 133 слов в минуту, удобный для шедоуинга. Только 76% слов входят в 3000 самых частых слов английского языка, поэтому лексика сложная.
Ключевая лексика этого видео
15 слов из видео, которые стоит выучить, с произношением и значением:
| Слово | Произношение | Значение |
|---|---|---|
| grid существительное | /ɡɹɪd/ | се́тка, решётка |
| connect глагол | /kəˈnɛkt/ | свя́зывать, связа́ть |
| voltage существительное | /ˈvəʊltɪd͡ʒ/ | напряже́ние, вольта́ж |
| transmission существительное | /tɹænsˈmɪʃən/ | переда́ча, перено́с |
| convert глагол | /kənˈvɝt/ | превраща́ть, преврати́ть |
| circuit существительное | /ˈsɝ.kɪt/ | кругооборо́т, цикл |
| frequency существительное | /ˈfɹiːkwənsi/ | частота́ |
| filter существительное | /ˈfɪltɚ/ | фильтр |
| bipolar прилагательное | /baɪˈpoʊ.lɚ/ | двухпо́люсный, биполя́рный |
| hence наречие | /ˈhɛns/ | отсю́да |
| ratio существительное | /ˈɹeɪ.ʃoʊ/ | отноше́ние, соотноше́ние |
| pole существительное | /pəʊl/ | по́люс |
| locate глагол | /ˈloʊˌkeɪt/ | помести́ть |
| diagram существительное | /ˈdaɪ.ə.ɡɹæm/ | план, диагра́мма |
| reactor существительное | /ɹiˈæktɚ/ | реактор |
Грамматика в этом видео
Конструкции, которые говорящий использует чаще всего, с точными словами из видео:
| Конструкция | В видео |
|---|---|
| Пассивный залог be + причастие прошедшего времени — важно, что происходит, а не кто это делает | are connected · is known · is called |
| Present Perfect have/has + причастие прошедшего времени — прошлое действие, важное сейчас | has installed · has chosen · has been chosen |
Произношение, на которое стоит обратить внимание
- Звуки «th»: theoretical /ˌθi.əˈɹɛt.ɪ.kəl/, smoothen /ˈsmuːðən/
- Звуки «sh» и «zh»: transmission /tɹænsˈmɪʃən/, ratio /ˈɹeɪ.ʃoʊ/, conversion /kənˈvɝʒən/, substation /sʌbˈsteɪʃən/, stabilization /ˌsteɪ.bəl.ɪzˈeɪ.ʃən/
- Длинные слова — следите за ударением: electrical /ɪˈlɛktɹɪkəl/, stability /stəˈbɪlɪti/, electronics /ɪˌlɛkˈtɹɑ.nɪks/, successfully /səkˈsɛs.fə.li/, electricity /ɪˌlɛkˈtɹɪsɪti/
Звуки, трудные для русскоязычных:
- Звонкие согласные в конце слова — не оглушайте их: grid /ɡɹɪd/, voltage /ˈvəʊltɪd͡ʒ/, installed /ɪnˈstɔːld/, upgrade /əpˈɡɹeɪd/, slide /ˈslaɪ̯d/
Как заниматься с этим видео
- Прослушайте всё видео один раз молча и выпишите незнакомые слова.
- Повторяйте предложение за предложением на обычной скорости, пока ваш ритм не совпадёт с ритмом говорящего.
- Запишите себя и сравните с оригиналом, обращая внимание на такие слова, как grid, connect, voltage.
Что такое техника Shadowing?
Shadowing — это научно обоснованная техника изучения языка, изначально разработанная для подготовки профессиональных переводчиков и популяризированная полиглотом доктором Александром Аргуэльесом. Метод прост, но эффективен: вы слушаете аудио на английском от носителей языка и немедленно повторяете вслух — как тень, следующая за говорящим с задержкой в 1–2 секунды. В отличие от пассивного прослушивания или грамматических упражнений, Shadowing заставляет мозг и мышцы рта одновременно обрабатывать и воспроизводить реальные речевые паттерны. Исследования показывают, что это значительно улучшает точность произношения, интонацию, ритм, связную речь, понимание на слух и беглость речи — что делает его одним из самых эффективных методов для подготовки к IELTS Speaking и реального общения на английском.