High Technology Blooms in the Tropics
Unexpected Heat in the Caribbean
In February of 1994, a fuel leak in a modest building on the north coast
of the Dominican Republic precipitated a blazing fire. It destroyed one
of three oil-fired engines at the power generating plant in Puerto Plata
and damaged a second one. The fire was a potential disaster to the tourism
industry, a major contributor to the economy (there are more hotel rooms
here than on any other island in the region). Clearly, the 18 megawatt
facility had to be returned to service as quickly as possible—ideally
no later than summer, to catch the fall/winter tourist season.
The damaged engine could be repaired. The destroyed
engine could be rebuilt. The control system, however, presented
a huge challenge. High temperatures during the fire had destroyed
the hundreds of connecting cables that organized, monitored, and
controlled the facility; their replacement was a daunting task,
expected to take several months. Wärtsilä Diesel, operator
of the plant for the Compania de Electricidad de Puerto Plata, turned
to Woodward Governor Company for a solution. |
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A Four-Wire Solution
Woodward, a world supplier of digital electronic control systems, has
provided innovative solutions to the industrial market since 1870. Their
new QuadraLink™ family of distributed control products offered not
only a state-of-the-art control solution, but the answer that everyone
was seeking to the rewiring question.
The QuadraLink product line is based on LonWorks technology. Indeed,
the name itself comes from the basic four-wire cable used to replace the
hundreds of cables (and associated junction cabinets) that are traditionally
part of large engine monitor and control systems. Two of the QuadraLink
wires carry 24 volt power throughout the control system; the remaining
two carry LonTalk communication at 1.25 Mbits/s, using standard Echelon
twisted-pair transceivers. “Each of the three 16-cylinder engines
requires about 100 analog and 35 discrete monitor points”, notes
David Fredlake, Woodward’s Manager of Power Generation Systems,
making obvious the potential for wire savings. The Puerto Plata site now
includes a network of some 50 QuadraLink modules, each designed around
a single Neuron Chip. This chip incorporates the three microprocessors,
program/data memory, interface electronics, and operating software—including
a full seven-layer communication protocol—that are necessary to
an “intelligent” sensor device, and that characterize a LonWorks
network node. The Puerto Plata installation employs the standard QuadraLink
dual-cable approach, providing system redundancy and making more bandwidth
available for critical traffic (the model 723 controller is designed to
manage control loops with service rates from 10–500 ms). Overall,
some 80 to 100 wire pairs (many being expensive thermocouple wires) were
saved for each engine.
“QuadraLink also establishes a platform for further system enhancement,
” notes Fredlake. “A next step at Puerto Plata might be engine
start/stop sequencing, also supported by the 723 controller. And the addition
of our DSLC [Digital Synchronizer and Load Control] product would allow
for the control of generator outputs and management of multiple generator
load sharing.”
Meeting
the Deadline
Delivering and installing the Woodward control system took six weeks,
a far cry from the typical three to four months that would have
been necessary using earlier technologies. Commissioning of the
restored power plant was completed in the summer of 1994, well ahead
of the tourist influx. With that success under his belt, Dave Fredlake
has five other systems in process, and 30 more planned for 1996.
Puerto Plata has resumed its co-status (with Santo Domingo) as the
island’s most reliable power source. And nobody misses those
cable junction cabinets. |
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Cable Junction Cabinets Obsoleted
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