various parts in hv dc

8/13/2019 Various Parts in Hv Dc

1/5

BIPOLE IIIPROJECT 3-72CHAPTER 3:PROJECT DESCRIPTION

Station Service Transformers

Station service transformers are required to serve the auxiliary power requirements of

the converter station including the ac switchyard, converter building, dc switchyard, and

ancillary buildings and equipment. Auxiliary power requirements include electrical loads

such as building heating and cooling, process cooling systems, lighting, and various othersupport systems needed for station operation. Three three-phase, two-winding, 230 kV-

12.47 kV MVA (mega volt-amperes) station service transformers will be required, each

containing approximately 35,000 litres of insulating oil.

Instrument Transformers

Instrument transformers measure currents (current transformers) and voltages (voltage

transformers) on apparatus within the 230 kV ac switchyard. Signals from the instrument

transformers are used for control, protection and monitoring purposes.

The Keewatinoow ac switchyard will require approximately 70 single phase voltagetransformers, each containing approximately 100 litres of insulating oil. The switchyard

will also require approximately 126 single phase current transformers, each containing

approximately 200 litres of insulating oil.

ac Harmonic Filters

Harmonic filters (see photo of existing ac harmonic filters at Dorsey Converter Station

in Figure 3.5-3) are typically required due to the ac current harmonics generated in the

process of converting ac power to dc power. These harmonics could be harmful to

equipment connected to the ac system, including generators, if allowed to flow out of

the converter station.


2/5

Figure 3.5-3:ac Harmonic Filters at Dorsey Converter Station


3/5


Depending upon the conversion technology selected for Bipole III23,as well as the

outcome of final design studies, Keewatinoow Station may require four three-phase ac

harmonic filter banks, each of which may be comprised of up to three sub-banks.

Operation of the sub-banks would be controlled using dedicated ac circuit breakers

similar to those described in this section. Eight such ac circuit breakers would be

required.The ac harmonic filter banks and sub-banks are typically comprised of a combination of

capacitors, reactors, and resistors. Filter capacitors are generally filled with an insulating

oil fluid. Approximately 1,100 capacitors, each containing approximately 16 litres of

insulating fluid, will be required for each ac harmonic filter bank.

Surge Arrestors

Surge arrestors provide protection to ac switchyard components from abnormally high

voltages induced from lightning. Surge arrestors are comprised of porcelain or

composite materials, and are similar in appearance to insulators.

Insulators

Insulators are non-conducting posts (porcelain or composite) used to support energized

equipment and hardware in the switchyard. Insulators are typically placed on the top of

steel equipment support structures, but may also be placed directly on the equipment

foundations.

Control Buildings

Two to four control buildings will be required for the Keewatinoow 230 kV ac

switchyard to house the control, protection, and communications equipment necessaryfor its operation. Cables will connect the control buildings to the ac switchyard

apparatus and to the remainder of the converter station. The control buildings typically

contain battery banks to meet the power requirements for the electrical equipment

installed within the building. Approximately 1,300 litres of battery acid will be contained

23Line-commutated converter (LCC) technology utilizes thyristor based power electronic conversionequipment similar to that in the Manitoba Hydro Bipole I and Bipole II converter stations. Voltage-

source converter (VSC) technology utilizes insulated gate bipolar transistor (IGBT) based powerelectronic conversion equipment. In addition to the valve group power electronic components, thedifferent conversion technologies under consideration for Bipole III have different requirements forac harmonic filters, the converter building, dc switchyard equipment, and synchronous condensers.


4/5


within the batteries in each control building. The control buildings will also require

heating and air handling equipment to control the building ambient temperature.

Switchgear Buildings and Auxiliary Power Distribution

Two switchgear buildings will be required within the ac switchyard. The buildings will

house equipment for control of the 12.47 kV auxiliary power from the station service

transformers to the converter station electric power loads. Each building will include

approximately 15 circuit breakers and the control and protection electronics necessary

for their proper operation. The buildings will require electric heat and air handling

equipment.

Power from the switchgear buildings to the converter station electric power loads will be

distributed throughout the station by power cables to indoor and outdoor power centres.

Each power centre will require two transformers approximately 2,500 kVA in size.

Outdoor power centres may utilize oil-filled transformers, each containing

approximately 2,200 litres of insulating oil. Indoor power centres, located within theconverter building, typically utilize dry-type transformers which do not contain insulating

oil. It is anticipated that four outdoor and four indoor power centres will be required for

Keewatinoow Converter Station.

3.5.2.3 Converter TransformersThe 230 kV ac switchyard will be electrically connected to converter transformers,

through which power is passed from the ac switchyard to the solid state power

electronic valve groups within the converter building. The converter transformers

provide an interface between the ac voltages in the ac switchyard and the dc voltages in

the valve groups.

Keewatinoow Converter Station will require up to fourteen converter transformers for

the conversion of ac to dc power - three for each of the four valve groups, and two

spares (for use during maintenance or outage).

The final layout design of the converter transformers will depend on such factors as the

HVdc system configuration, converter building size and layout, ac filtering and reactive

power compensation requirements.

In order to obtain a more compact station design and reduce the number of insulated

high voltage wall bushings, converter transformers may be situated adjacent to the

converter building with the valve group side connections protruding into the valve hall.

This configuration reduces buswork requirements and improves protection of the valve

group from lightning strikes. Alternatively, if the converter transformers are not situated


5/5


adjacent to the converter building, approximately 48 wall bushings will be required in the

converter building wall between the converter transformers and the valve halls.

The principal components of individual converter transformers are the tank which

includes the transformer core and copper windings, transformer bushings, and oil

cooling radiators and fans.The converter transformers are filled with insulating oil for electrical insulation and heat

transfer purposes. Insulating oil is circulated between the tank and the cooling radiators,

where excess heat is transferred to the air. Each converter transformer (see photo of

existing converter transformer at Dorsey Converter Station in Figure 3.5-4) will contain

approximately 115,000 litres of insulating oil. Due to the volume of insulating oil in each

transformer, the design will incorporate primary oil containment (see Section 3.5.2.1).

various parts in hv dc

Documents