IEEE Power & Energy Magazine - March/April 2016 - 35

the existing converter equipment at both the Intermountain and Adelanto converter stations, which
consisted of upgrading the converter transformers; dc yard modifications; ac and dc filter modifications including the addition of a new filter bank
4; adding subbranches to existing filter banks 1,
2, and 3 for redundancy and reliability; upgrading
the valve cooling system; changing out the pneumatic controls to electrical controls; and replacing
the entire converter control system. Each pole now
has a 1,600-MW overload capacity to minimize the
impact of a pole outage.
In addition, a new 500-kV ac switchyard position at both stations and one additional station service 500 kV position at Adelanto were constructed.
The scope also included contingency arming system and remedial action scheme modifications for
both converter stations.

Asynchronous Borders

NPCC
MAPP
ECAR

WECC

MAAC

MAIN
SPP

SERC

ERCOT

FRCC

figure 1. Synchronous power systems in North America.

Ontario, California. Built by ASEA, the system was commissioned in 1986 and originally rated at 1,600 MW with a
continuous 50% overload capacity. This overload capacity
was exploited in 1989 when the capacity was increased to
1,920 MW. No equipment changes were required since each
pole was originally rated at 1,200 MW. See Figure 2 for a
typical HVdc converter station.
An additional 480 MW of capacity was added in 2010,
when a major upgrade project was completed to transfer
additional renewable power from a wind farm in Utah. The
scope for this extensive upgrade included modification to

Trans Bay Cable
Built in 2010, the Trans Bay HVdc cable connects a substation in downtown San Francisco with a substation in
the northern part of San Francisco Bay at Pittsburg. Using
voltage source converters, the cable is rated at 400 MW,
±200 kV, and extends for 88 km (55 mi). A project is underway for 2016 to modify the converter stations to provide
black start capability for the San Francisco end. Control and
valve modifications will be required along with a diesel generator for the converter station in San Francisco.

table 1. HVdc systems in the WECC.

Name

Type

Year

Rating

Status

Vancouver Island

Transmission

1968, 1979

312, 370 MW

Operational

PCDI

Transmission

1970, 1984, 1989,
2003, 2016

1,440, 2,000, 3,100,
3,800 MW

Refurbishing scheduled
for completion in 2016

Intermountain power
project

Transmission

1986, 2010

1,920, 2,400 MW

Operational

Transbay cable

Transmission

2010

400 MW

Operational

Alberta east link

Transmission

2014

1,000 MW

Operational

Alberta west link

Transmission

2014

1,000 MW

Operational

David A. Hamil

Back to Back

1977

100 MW

Operational

Eddy County

Back to Back

1983

200 MW

Operational

Blackwater

Back to Back

1985

200 MW

Renovated in 2009

Miles City

Back to Back

1985

200 MW

Retired

Virginia Smith

Back to Back

1987

200 MW

Operational

McNeil

Back to Back

1989

150 MW

Control upgrade in 2013

Rapid City

Back to Back

2003

200 MW

Operational

Lamar

Back to Back

2005

210 MW

Operational

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