POWER October 2012 - 26

load up these lines, you build up resistance, but by using synchronous
condensing, you can boost the power factor up to a
higher level and stabilize the voltage. "
A simple way to achieve this is to use the quick-start gas
turbines as synchronous condensers. By putting a clutch between
the turbine and the generator, the generator can stay
synchronized to the grid, providing the necessary reactive power.
Then, when active power is needed to compensate for a drop
in renewable output, the turbine can quickly fire up, the clutch
engages, and the unit starts generating electricity. Because the
generator is already synchronized to the grid, the unloaded turbine
can reach synchronous speed quicker, and there is less
wear on the turbine from the frequent stops and starts. (See
" How to Make VARs-and a Buck, " June 2007 and " CFE Extends
CTG Universidad Unit 2's Life with Conversion to Synchronous
Condenser, " August 2011 in the POWER archives for more information
on the value of synchronous condensers.)
Utilities throughout the world have been installing clutches
that allow idle generators to provide synchronous condensing
for more than 30 years. Here are four examples of how this approach
has worked to address different situations:
■ British Columbia. Thirty-two hydroelectric plants provide
BC Hydro with 87% of its generating capacity. To correct
the poor power factor of the electricity coming from the
remote generators, BC Hydro converted the six 150-MW
steam turbine generators at a thermal plant in the Vancouver
area to operate as synchronous condensers. From April
to October, these generators provide electricity, and water
is allowed to build up behind the dams. During the other
half of the year, when natural gas is needed for residential
heating, five of the generators are disconnected from the
turbines and provide voltage support for the hydro power.
Not only did this improve stability in Vancouver, it also
improved the power factor enough to allow the utility to
sell more power to U.S. customers.
■ Western Australia. In Western Australia, three-quarters of
the population lives in or near the city of Perth, but much
of the generation has switched to steam plants located at
coal mines, cogeneration facilities, alumina refineries, and
the 180-MW Emu Downs Wind Farm, all of which are located
about 200 kilometers from the city center. To provide the
necessary reactive power near Perth, Verve Energy recently
retrofitted three of the nine GE Frame 6 turbines at its Pinjar
Gas Turbine Power Station with clutches so they can
operate as synchronous condensers when not generating
power, joining the three units that originally came with
clutches 20 years ago.
■ Los Angeles. The Los Angeles Department of Water and Power
(LADWP) is in the middle of a repowering project at its
Haynes Power Station. Although the project was mandated
by a state regulation limiting the use of seawater for cooling,
LADWP is using switching to GE LMS100 generators to
give it the quick-start capabilities needed to support its
increasing renewables portfolio and is installing clutches
on two of the units so they can provide necessary voltage
support when peaking isn't required.
■ Key West. The City of Key West, Fla., has its own local generating
station but found it was more economical to import
power from the mainland. In 1987 it started using dual 138
kV transmission lines to connect with a Florida Power & Light
station 185 miles away. However, because the City of Key
West was at the end of a radial system and lacked voltage
26
support, the transmission lines lacked the ability to carry
enough power to meet rising demand. In 1997, Key Energy
Services converted a decommissioned steam generating unit
into a synchronous condenser, boosting the transmission
lines' capacity by 34 MW and improving stability.
Some ISOs, including PJM Interconnection and the Midwest
ISO, have markets for synchronous condensing, which make it
profitable for power producers to install clutches and provide
voltage support. In California-although LADWP, which manages
its own grid, is setting up some of its new LMS100s to
provide synchronous condensing-for the state as a whole,
CAISO does not have such a market, which limits the incentive
for independent power providers to provide voltage support.
However, as California looks to increase its renewable sources
and back them up with gas turbines, such a market may be
needed to provide the incentive for producing low-cost reactive
power to help stabilize the grid. ■
-Contributed by Joe Zwers, a freelance writer from Glendale,
Calif., specializing in engineering and technology.
Predictive Maintenance That Works
This is the sixth in a series of predictive maintenance (PdM) articles
that began in the April 2011 " Focus on O&M " in which the
essentials of PdM were introduced. In this occasional segment,
we have explored specific PdM techniques, such as motor-current
signature analysis, oil analysis and thermographic analysis and
their routine use, and ultrasonic and vibration analysis. In this
issue we look at lubricating oil wear-particle analysis.
Wear-Particle Analysis
Wear-particle analysis can be used to determine the type, location,
and severity of component wear occurring within the
lubrication or hydraulic system of a machine. This information
can be used to troubleshoot suspected machine problems
and project an estimated time to failure. The technique allows
equipment wear problems to be identified prior to serious deterioration
or failure so that repairs can be made on a planned
basis during scheduled downtime. Wear-particle analysis can be
used on machines that have a circulating oil system, including
steam and gas turbines, generators, hydraulic systems, diesel
and gasoline engines, gearboxes, and compressors. For the most
accurate results, samples should be taken from an active, lowpressure
line, ahead of any filtration devices. For consistent
results and accurate trending, samples should be taken from
the same place in the system each time; using a permanently
installed sample valve is highly recommended.
Most independent labs supply sample containers, labels,
and mailing cartons. If the wear-particle analysis is to be
done by a lab, all that is required is to take the sample; fill
in information about the machine number, machine type, and
sample date; and send it to the lab. Results are normally
available within 24 to 48 hours of receipt of the sample at
the lab. If the analysis is to be done onsite, analytical equipment
must be purchased, installed, and standardized. Once a
sample is taken, information about it is entered on the form,
it is taken to the onsite lab, and the results are available as
soon as the analysis can be scheduled.
If an in-line measurement device is used, a permanent sample
port or monitor must be installed. Wear-particle concentrations then
can be monitored continuously and the results of the analysis made
immediately available. Some instruments allow data to be downloaded
directly to a computer for trending and further analysis.
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POWER | October 2012
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POWER October 2012

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