Investing $2 million on a system you hope you never have to use may seem odd, but it made perfect sense to the city of Coffeyville, KS. The city wanted to ensure that their community would never be left in the dark, no matter what Mother Nature threw at it. That’s why Coffeyvile built a “black-start” generation facility, featuring two Baldor 2000-kilowatt (kW) generators that would start its main power plant in the event of the loss of electric power from the transmission grid.
The Coffeyville Power Plant, a gas-fired facility, began serving the community in 1901. But as natural gas prices began to rise in the early 80s, older plants like this were no longer an economical way to generate power. Instead, the city began to purchase power from the Grand River Dam Authority (GRDA) through a transmission grid that supplies power to municipalities throughout the Midwest.
Over the past several years, the Coffeyville plant was only powered up during peak use periods, generally in the hot summer months. However, since the plant actually needs electricity to start up, city officials wanted to make sure they could run the plant, even if the grid went off line.
Bernard Cevera, the director of electric utilities for the city, says that’s when the city decided to have the black-start facility built. “We wanted this system as our insurance policy,” says Cevera. “A black-start unit provides a reliable power supply, allowing us to serve our citizens and prevent the critical public health and safety issues that develop when a community loses electricity.”
With the goal of making their plant reliable 24/7, the city awarded the contract to build the black-start facility to Emergency Power Systems, based in Tulsa, OK. EPS has been in business since 1991 and specializes in custom designs and turnkey installations of power generation facilities.
Ron Haynes, an owner of EPS, says that when his company was awarded the contract there was no question about which brand of generators would be installed. “We had too much at stake to not use Baldor generators in this facility,” says Haynes. “We have sold Baldor generators for many years, and we know the quality of the product. We have had a history of success with Baldor, and we were comfortable with our choice.”
The project was completed in 12 months, from the design phase all the way to final commissioning. An external 25,000-gallon main tank fuels the 16-cylinder engines on the generators. EPS packaged two 2000-kW diesel gen sets with a 15-kilovolt custom paralleling switchgear system, complete with touch screen operator controls.
The master controls feature a programmable logic controller for data acquisition and system control, HMI touch screen for display and monitoring of the engine and gen set functions, an inter-tie protection relay, and a digital power meter. The gen sets include a microprocessor-based control package, digital power meter, and multifunction protection relay. Each gen set controller allows full bias of engine speed for precise load control. It also integrates with the alternator voltage regulator for output voltage and power factor control. All relays, controllers, and power meters are tied to the master PLC with MODBUS, CAN BUS, or RS485 communications. From the PLC, all operational data is communicated and displayed on the local HMI and a remote customer PC. Operators have full control of the system from several screens within the local HMI touch screen or their PC.
The control system is fully automatic; however it is manually initiated in a typical utility power outage. When needed, the black-start gen sets are manually started and paralleled together to the power plant generator bus. The utility main switch is manually opened while the tie in breaker is manually closed, at which time the black-start generators share the load being served to the gas-fired power plant.
When peak shaving is desired, the system operates in its most automated mode. From the HMI touch screen or remote PC, the operator places the master selector switch to the “peak shave” position. The tie in breaker automatically closes, energizing the generator bus from the utility grid. The master PLC sends a signal to each gen set to start. The gen set controllers automatically synchronize each gen set to the generator bus and close the gen set circuit breakers. Once the generators are closed to the bus, the gen set controller ramps the generator load up to the preset kW level. The gen sets export power until the master selector switch is returned to the off position at which time the gen sets are soft unloaded. The gen set circuit breakers are opened, the tie in breaker is opened, and the gen sets are allowed to cool down and finally shut down.
There are two test modes available for the operator to select, “test with load” and “test without load”. Both test modes operate similar to the peak shaving operation. The “test with load” mode operates with the operator setting the desired base kW load. The “test without load” mode operates without closing the tie in breaker. The master controller can still test all facets of the gen set controls, including the first gen set closing to the dead generator bus, and the second gen set synchronizing to the generator bus that is energized only by the first gen set.
While EPS had the systems knowledge plus the experience handling turnkey projects like this one, Haynes is quick to share credit for the success of the project with Baldor generator engineers. “The direct and easy access to Baldor engineers was critical for this project,” says Haynes. “This was a big project for us and it was important for us to interface with the Baldor team. We never wasted time waiting for answers because Baldor was very responsive to our needs, enabling us to stay on track and finish the project on time.”
Working with a manufacturer that is willing to customize their product based on customer needs was another reason for the success of the project according to Haynes. Since the generators are tied into the sub-station, Haynes requested some modifications be made to the units, including a request for a medium-voltage alternator that could be packaged with the custom switchgear.
“Whatever I needed,” says Haynes, “Baldor was willing to do because they are not a cookie cutter manufacturer.”
With the project complete, the Coffeyville plant will be operated in a new mode called “ready state”, meaning that they will be able to be up and running within 24 hours notice from GRDA. By having the flexibility to start the plant at any time, under any conditions, the city is helping the GRDA meet its regulatory obligation for reserve power. It’s a service the GRDA is willing to pay for. “Building the black-start plant means that our town will be ready for any disaster, but it also means the town has a new revenue source,” explains Cevera. “By guaranteeing that we are in a “ready state”, the city now receives $220,000 per month in a capacity payment from the GRDA.”
Cevera says they haven’t yet calculated the other benefits they may gain with load shedding and peak shaving strategies. “The flexibility to produce power will offer us additional benefits that we have not quantified,” says Cevera. “But it’s clear that adding the black-start generators makes our plant the most valuable asset the city owns.”
In the months since the black-start unit was commissioned, the city has not had to start the facility for any emergency needs – and Cevera says that’s just the way he wants to keep it. However, the system is tested every three weeks to make sure that everything is working properly. “We validate the system on a regular schedule by actually exporting kW to the grid,” says Cevera. “We have not once been disappointed by the system – in fact we are very pleased. The black-start works as well as it looks.”