20:
408:
285:
347:
427:" connection of the transformer windings, the converter can operate with 12 pulses for each cycle in the AC supply, which eliminates numerous harmonic current components. The insulation of the transformer windings must be specially designed to withstand a large DC potential to earth. Converter transformers can be built as large as 300 Mega volt amperes (
431:) as a single unit. It is impractical to transport larger transformers, so when larger ratings are required, several individual transformers are connected together. Either two three-phase units or three single-phase units can be used. With the latter variant only one type of transformer is used, making the supply of a spare transformer more economical.
316:. In thyristor-based converters, many thyristors are connected in series to form a thyristor valve, and each converter normally consists of six or twelve thyristor valves. The thyristor valves are usually grouped in pairs or groups of four and can stand on insulators on the floor or hang from insulators from the ceiling.
516:
Beside the harmonic filters, equipment is also provided to eliminate spurious signals in the frequency range of power-line carrier equipment in the range of 30 kHz to 500 kHz. These filters are usually near the alternating current terminal of the static inverter transformer. They consist
570:
Converter stations produce acoustic noise. Converter stations can generate serious levels of radio-frequency interference, so include design features to control these emissions. Walls may provide noise protection. As with all AC substations, oil from equipment must be prevented from contaminating
451:
is located close to the static inverter plant, the generators in the power station. The demand for reactive power can be reduced if the converter transformers have on-load tap changers with a sufficient range of taps for AC voltage control. Some of the reactive power requirement can be supplied in
561:
The area required for a converter station is much larger than a conventional transformer, for example a site with a transmission rating of 600 megawatts and a transmission voltage of 400 kV is approximately 300 x 300 metres (1000 x 1000 feet). Lower-voltage plants may require somewhat less ground
463:
Harmonic filters are necessary for the elimination of the harmonic waves and for the production of the reactive power at line commutated converter stations. At plants with six pulse line commutated converters, complex harmonic filters are necessary because there are odd numbered harmonics of the
374:
and 1 H. The smoothing reactor can have either an air-core or an iron-core. Iron-core coils look like oil-filled high voltage transformers. Air-core smoothing coils resemble, but are considerably larger than, carrier frequency choke coils in high voltage transmission lines and are supported by
434:
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 three-phase power transformers. This effect should be considered in the siting of an HVDC converter station. Noise-reducing enclosures may be
394:
filters or active filters, consisting of an amplifier coupled through transformers and protection capacitors, which gives a signal out of phase to the interference signal on the line, thereby cancelling it. Such a system was used on the
379:. Air coils have the advantage of generating less acoustical noise than iron-core coils, they eliminate the potential environmental hazard of spilled oil, and they do not saturate under transient high current
319:
Line commutated converters require voltage from the AC network for commutation, but since the late 1990s, voltage sourced converters have started to be used for HVDC. Voltage sourced converters use
540:
for overcurrent protection of the converter transformers, isolating switches, grounding switches, and instrument transformers for control, measurement and protection. The station will also have
443:
When line commutated converters are used, the converter station will require between 40% and 60% of its power rating as reactive power. This can be provided by banks of switched capacitors or by
513:
Voltage sourced converters generally produce lower intensity harmonics than line commutated converters. As a result, harmonic filters are generally smaller or may be omitted altogether.
326:
Almost all converters used for HVDC are intrinsically able to operate with power conversion in either direction. Power conversion from AC to DC is called
571:
ground water in case of a spill. Substantial area may be required for overhead transmission lines, but can be reduced if underground cable is used.
428:
455:
Voltage sourced converters can generate or absorb reactive as well as real power, and additional reactive power equipment is generally not needed.
510:(on the DC side) result. Filters are tuned to the expected harmonic frequencies and consist of series combinations of capacitors and inductors.
386:
Special direct current filters are used to eliminate high frequency interference. Such filters are required if the transmission line will use
204:
520:
In special cases, it may be possible to use exclusively machines for generating the reactive power. This is realized at the terminal of
139:
390:
techniques for communication and control, or if the overhead line will run through populated areas. These filters can be passive
590:
536:
The three-phase alternating current switch gear of a converter station is similar to that of an AC substation. It will contain
101:
633:
614:
289:
638:
320:
383:
conditions. This part of the plant will also contain instruments for measurement of direct current and voltage.
197:
609:
Arrillaga, Jos; High
Voltage Direct Current Transmission, second edition, Institution of Electrical Engineers,
370:
in series with the DC line to help smooth the direct current. The inductance typically amounts to between 0.1
643:
525:
230:
190:
38:
67:
53:
387:
19:
487:
on the DC side. At 12 pulse converter stations, only harmonic voltages or currents of the order
585:
521:
517:
of a coil which passes the load current, with a parallel capacitor to form a resonant circuit.
562:
area, since less air space clearance would be required around outdoor high-voltage equipment.
580:
444:
424:
376:
252:
226:
110:
8:
234:
541:
407:
82:
77:
610:
305:
258:
153:
62:
46:
178:
537:
130:
120:
323:
instead of thyristors, and these can provide power to a deenergized AC system.
312:
have been used. Converters using thyristors or mercury-arc valves are known as
279:
238:
158:
148:
125:
92:
627:
448:
380:
115:
396:
371:
351:
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416:
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301:
545:
328:
309:
87:
359:
334:
173:
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24:
420:
293:
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28:
300:
The converter is usually installed in a building called the
233:(HVDC) transmission line. It converts direct current to
350:
HVDC cable termination and DC smoothing reactor on the
308:, but since the mid-1970s, solid state devices such as
480:
produced on the AC side and even harmonics of order
423:
of the AC supply network. Using a star-to-delta or "
411:
A single-phase, three-winding converter transformer.
288:
Valve hall at Henday converter station, part of the
625:
358:The direct current equipment often includes a
198:
245:three-phase alternating current switch gear
205:
191:
229:which forms the terminal equipment for a
544:for protection of the AC equipment from
406:
402:
345:
283:
18:
332:and conversion from DC to AC is called
626:
591:High-voltage transformer fire barriers
237:or the reverse. In addition to the
565:
458:
290:Nelson River DC Transmission System
13:
321:insulated-gate bipolar transistors
14:
655:
438:
140:Electric power systems components
556:
531:
452:the harmonic filter components.
241:, the station usually contains:
341:
603:
1:
596:
268:
261:for harmonic suppression, and
102:Electric power infrastructure
273:
7:
634:High-voltage direct current
574:
526:Volga Hydroelectric Station
304:. Early HVDC systems used
264:direct current switch gear.
231:high-voltage direct current
225:) is a specialised type of
10:
660:
314:line commutated converters
277:
639:Electric power conversion
551:
548:surges on the AC system.
68:Electric power conversion
54:Electric power conversion
449:power generating station
388:power-line communication
586:Rotary converter plant
522:HVDC Volgograd-Donbass
445:synchronous condensers
412:
355:
297:
253:synchronous condensers
219:HVDC converter station
73:HVDC converter station
31:
581:List of HVDC projects
410:
403:Converter transformer
349:
287:
111:Electric power system
22:
503:(on the AC side) or
542:lightning arresters
447:, or if a suitable
235:alternating current
644:Converter stations
413:
356:
306:mercury-arc valves
298:
255:for reactive power
83:DC-to-DC converter
78:AC-to-AC converter
32:
23:Dorsey Station in
16:Type of substation
223:converter station
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154:Grid-tie inverter
63:Voltage converter
47:Power engineering
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566:Location factors
538:circuit breakers
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459:Harmonic filters
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179:Protective relay
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131:Demand response
121:Electrical grid
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439:Reactive power
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415:The converter
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399:HVDC project.
343:
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280:HVDC converter
278:Main article:
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251:capacitors or
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159:Energy storage
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149:Ring main unit
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126:Interconnector
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615:0 85296 941 4
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557:Required area
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532:AC switchgear
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329:rectification
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116:Power station
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605:
569:
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524:situated on
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512:
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442:
433:
419:step up the
417:transformers
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397:Baltic Cable
385:
366:) that adds
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352:Baltic Cable
342:DC equipment
333:
327:
325:
318:
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299:
248:transformers
222:
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216:
72:
221:(or simply
628:Categories
597:References
377:insulators
368:inductance
362:(called a
354:HVDC link.
310:thyristors
302:valve hall
269:Components
227:substation
546:lightning
435:applied.
425:wye-delta
335:inversion
274:Converter
239:converter
88:Rectifier
575:See also
174:Recloser
169:Bus duct
93:Inverter
39:a series
37:Part of
25:Manitoba
617:, 1998.
464:orders
421:voltage
364:reactor
259:filters
613:
552:Others
294:Canada
164:Busbar
29:Canada
381:fault
611:ISBN
495:and
472:and
360:coil
501:- 1
493:+ 1
478:- 1
470:+ 1
429:MVA
292:in
217:An
630::
528:.
505:12
497:12
489:12
392:LC
338:.
41:on
27:,
507:n
499:n
491:n
484:n
482:6
476:n
474:6
468:n
466:6
372:H
296:.
206:e
199:t
192:v
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