First published in Electrical Generating Systems Association's POWERLINE July/August 2013 and republished with permission.
How productive are conversations around the water cooler? Ironically, as water cooler technology improves, so does the level of discussion that occurs around them. This was especially true for two engineers from L3 Westwood, a supplier of power generation equipment to the U.S. military, who were having a brainstorming conversation around a water cooler. Little did the engineers know that a marketeer would be eavesdropping on their water cooler conversation and make their idea a reality. That conversation – one that involved developing a means of connecting generator sets into a ring bus configuration and cycling them on and off as load demands – resulted in a new product that will save millions of gallons of fuel, and more importantly, reduce the amount of casualties on the battlefield.
With a production contract coming to an end that yielded almost 20,000 Tactical Quiet Generator Sets (TQGs) for the U.S. Army, Product Manager – Mobile Electric Power (PM-MEP), L3 Westwood turned their attention to providing their customers with improvements to existing equipment. Currently designed for a 20-year life cycle, the TQGs are manufactured in two output sizes by L3 Westwood to provide 30 kW and 60 kW, 120/208 V, three-phase AC power. These sets are used in a variety of roles by the military, including as a way to provide power to expeditionary camps in remote locations. The majority of these camps in the U.S. Army are managed by Project Manager – Force Sustainment Systems (PM-FSS) and are set up to house from 50 to 150 forward operating troops. Reliable power is necessary to support daily living activities, such as cooking, laundry and waste management. To maximize the efficiency of TQGs already in place, L3 Westwood has worked in conjunction with PM-FSS for the past two years to test its Load Demand Start Stop (LDSS) system in a simulated forward operating base.
LDSS System Fuel Savings
Fuel is the most precious commodity on the battlefield. Diesel engine-driven generator sets are the largest consumers of fuel on the battlefield during wartime1. In fact, they consume even more fuel than all the trucks, armor and personnel carriers being used. Generator sets operating as a standalone power supply are not efficient users of fuel. But, generator sets configured to operate together provide a much more fuel-efficient source of power. Imagine how much electricity would cost if everyone had to have their own power company for their home versus purchasing power collectively from the local utility and only paying for what they use. The same principal applies in Army camps. L3's LDSS system uses smart technology to ensure soldiers get the amount of power needed without having to continually run generator sets that consume energy and resources. L3's LDSS system turns a group of mobile generator sets into a "utility company," providing electricity as needed, and only charging for that amount. The net result is significant fuel savings. A micro-grid of six 60 kW generator sets tested by PM-FSS has resulted in excess of 35 percent fuel savings over what was being required to provide the same amount of power at a camp.2 Preliminary testing by other branches of the Army are showing results in excess of 50 percent fuel savings.
While this is the primary fuel savings associated with the LDSS system, there are other fuel savings on the battlefield as well. The amount of fuel convoys needed is proportionately reduced by the amount of fuel required to operate the generator sets. Accordingly, fuel required for convoy vehicles is reduced, as is the fuel required by equipment used in the logistics pipeline.
Compounded Benefits of the LDSS System
U.S. Sen. Jim Inhofe (R-Okla.), Ranking Member of the Senate Armed Services Committee, Ms. Sharon Burke, Assistant Secretary of Defense for Operational Energy Plans and Programs, and Clayton McClain, President of L3 Westwood.
The event was a visit to announce a new $13.5 Million contract for Load Demand Start Stop (LDSS) systems conducted April 19, 2013.
Perhaps the most important benefit of L3's LDSS system is the reduction in personnel handling and transporting of fuel, as well as associated casualties. Forward operating camps are often placed in remote locations. Transporting fuel to these locations is more than a matter of loading it on a truck and driving to the site. Advance scouting is needed to clear a route and make it as safe as possible. Roadside bombing of fuel convoys is a regular occurrence. These convoys require guarding in the form of extra personnel.
In a recent visit to L3 Westwood in Tulsa, Okla., both Sen. James Inhofe, ranking member of the Senate Armed Services Committee, and Ms. Sharon Burke, Assistant Secretary of Defense for Operational Energy Plans and Programs, made note of this.
Senator Inhofe remarked, "Advancements in defense technologies continue to decrease the level of risk our service members face while defending global U.S. interests. L3 Westwood's Load Demand Start Stop system will reduce fuel usage by up to 50 percent, reduce overall maintenance cost, enhance combat capability and lessen combat risk of our troops overseas."
ASD Burke commented, "Talk to anybody who's been (in Iraq or Afghanistan) and they have a story about someone they know who's either been hurt or killed moving fuel, protecting the movements of fuel and clearing the routes," she said.
How Does the LDSS System Save on Maintenance Costs?
In a traditional camp configuration, multiple generator sets run the majority of the time to ensure that power can be provided to meet the soldiers' daily needs. This often results in numerous generator sets running in different areas of the camp, with only a few providing power at the top end of their output capability, where fuel consumption is most efficient, and the rest running to meet very low-power output requirements. The majority of these sets consume fuel at a much higher gallon- to-power ratio. This results in more demand for fuel, which in turn results in increased demand for deliveries from fuel supply convoys. Also, when generator sets run at lower outputs, the fuel is not burned as efficiently and creates a problem in the industry called "wet stacking." Wet stacking occurs in diesel engines when fuel that is not burned passes through the exhaust side of the turbocharger into the exhaust system. In diesel generators, this is usually because the diesel engine is running at only a small percentage of its capacity. When this happens, maintenance on the generator sets is required more frequently.
Installation of the LDSS system allows the generator sets to be operated in a manner that reduces usage, spreads operation hours evenly across the sets in the grid, and reduces wear and tear associated with things such as wet stacking. All of these benefits result in less hours spent maintaining the sets, reducing associated parts and labor cost.
The LDSS system is a field-installable power grid management system designed to interface with the 30 kW MEP-805B and 60 kW MEP-806B TQG sets, or even a combination of the two sizes. This allows output power capability from 60 kW to 360 kW in a micro-grid. The game-changing feature of the system is that it will automatically start and stop TQGs based on electrical load requirements. The LDSS system allows as few as two and as many as six generator sets to operate on a common bus, maximizing fuel efficiency, reducing scheduled maintenance and reducing the potential for power outages to critical equipment.
Following startup and initial loading of the first TQG, the remaining generator sets are started and stopped automatically by the LDSS system, based on overall system load. As the load increases, additional generator sets start automatically and synchronize to the bus in order to meet the increased load demand. Load is automatically shared equally between online generator sets. As load decreases, generator sets are automatically removed from the bus, cooled down, and then shut down and returned to standby status. The block diagram below illustrates the primary components of the LDSS system. These components interface with the TQGs and each other to provide a complete micro-grid.
The components are:
- • Controller – Housed within an enclosure assembly, the digital controller is integrated into the TQG, making automatic operation of the generator sets possible. The controller can be accessed from its front-panel Human-Machine Interface (HMI), where an operator can make setting changes or display metering values dependent on level of password authority. Various pre-alarms and alarms are provided to notify the operator of the state of the equipment, ranging from a weak battery to an over-speed condition. The controller is equipped with CANbus and RS-485 communications capabilities. The CANbus link is utilized for communicating load-sharing requirements. The RS-485 utilizes Modbus protocol, offering optional monitoring and control of the controller over a polled network to a remote personal computer.
- • Powerline Communications (PLC) Adapter – Housed within the LDSS system enclosure assembly, the PLC converts Ethernet communications from the controller into a communications protocol that is transmitted over load cables between the generator sets. The PLC eliminates the need to have additional communication wires running between generator sets.
- • Multi-Unit Paralleling (MUP) Box – Interconnects load-sharing circuits to allow operation of more than two TQGs.
- • 200A Grid Personnel Protective Device – Provides connection capability to a common ring bus with enhanced personnel safety features. Features include the capability of isolating the generator load terminal board from the grid when the generator is not operating and the capability to isolate a generator set for maintenance activities.
- • Distribution Box – Rugged distribution /feeder boxes, designed for outdoor use, that facilitate connection of the TQGs into a ring bus distribution system. The distribution boxes also isolate individual TQGs for maintenance.
Greater Controllability for Greater Cost Savings
The advanced controller capabilities of the LDSS system give users the flexibility to program functions of the generator sets in the micro-grid for even greater cost savings.
The controller used with L3's LDSS system provides five different management modes, allowing the user to change con- figuration settings to more efficiently manage the generator set sequencing as related to the site-specific load profile and /or maintenance preference.
- In the smallest unit ID first mode, the generator sets will seek to sort the start priority in ascending order accord- ing to the sequencing ID. In this configuration, a net- work of generator sets will respond to a demand start request by starting the generator set with the smallest sequencing ID.
- In the staggered service time mode, the generator sets will seek to sort the start priority in ascending order of service hours remaining. In this configuration, a network of generator sets will respond to a demand start request by starting the generator set with the least number of service hours remaining first.
- In the balanced service time mode, the generator sets will seek to sort the start priority in ascending order of service hours remaining. In this configuration, a network of generator sets will respond to a demand start request by starting the generator set with the greatest number of service hours remaining first.
- In the largest size first mode, the generator sets will seek to sort the start priority in descending order of real load capacity. In this configuration, a network of generator sets will respond to a demand start request by starting the generator set with the largest load capacity first.
- In the smallest size first mode, the generator sets will seek to sort the start priority in ascending order of real load capacity. In this configuration, a network of units will respond to a demand start request by starting the unit with the smallest load capacity first.
The ability to use different operation modes allows more efficient scheduling of routine maintenance activities, reducing maintenance man-hours and equipment downtime. Incorporation of mobile micro-grid systems in military operations will also reduce the number of generator sets required to provide power to camps, further reducing overall maintenance time.
As ASD Burke notes, "All of our gear requires power. It's the communications. It's the computers. It's the GPS. It's the radios." While micro-grids for mobile power generation are a major step in saving fuel, there are a number of technologies either developed or in development that will contribute to this cause.
These technologies are being explored by a number of companies and will enhance the current fuel savings of the LDSS system.
Energy Storage Units (ESUs) are another means for reducing fuel consumption. While not as effective, they provide a way to harness power from a generator set and store it, usually in a bank of batteries, and then supply the power as needed. Opera- tion of an ESU is much quieter than a generator set and could be used to supply power for a short period of time when a camp would not want to run generator sets. ESUs can also provide what's known as "load shedding" capability. Load shedding is the deliberate switching off of electrical supply to parts of a grid. Load shedding can be required when there is an imbalance between demand and supply. While this technology is currently constrained to some degree by size, weight and safety concerns, these issues will be overcome in the near future.
Photovoltaic (solar) equipment can also reduce fuel consumption. Solar equipment, like energy storage equipment, is current- ly being used by the military. Solar panels are either configured and mounted on a piece of mobile equipment so that they can be deployed as part of a power supply package, or are used in a smaller design that can be rolled up when not in use, much like a sleeping bag. A drawback of solar power is that there must be sunlight to store the energy, and the space required versus power provided is much more than a generator set.
Harnessing wind power is being tested in camps as well. However, like solar, it relies on the environment and doesn't provide a great deal of power for the space required.
Wherever energy technologies are headed, the goal is to use less fuel, resulting in major savings for our military operations. There is a conscious effort within government and industry to invest in research and development in these areas for the good of all. The LDSS system demonstrates L3 Westwood's commitment to supporting our troops and reducing overall cost in the defense budget without sacrificing readiness or safety. During his visit, Senator Inhofe commented, "L3 Westwood's Load Demand Start Stop system will reduce fuel usage by up to 50 percent, reduce overall maintenance cost, enhance combat capability and lessen combat risk of our troops overseas. Furthermore, at a time when our Defense Department is facing unprecedented budget cuts, this technology will be key to improving the efficiency and effectiveness of our military."
L3 Westwood President Clayton McClain is committed to delivering innovation and affordable solutions. "We are proud that the U.S. Army has chosen to field our new LDSS system," he remarked. "The LDSS system gives us the ability to deliver even greater savings to our customers, and we will continue to research and develop new technologies for further fuel savings, including adapting the LDSS system to a variety of both commercial and military generator set power applications."
1 Report of the Defense Science Board Task Force on DoD Energy Strategy, Office of the Under Secretary of Defense For Acquisition, Technology, and Logistics, February 2008
For Acquisition, Technology, and Logistics.
2 DoD Project Manager Mobile Electric Power Program Update to the Electrical Generating Systems Association, 2012 Spring Technical & Marketing Conference, March 2012.
"This presentation consists of L3 Communications Corporation general capabilities information that does not contain controlled technical data as defined within the International Traffic in Arms (ITAR) Part 120.10."