Combining Fuel Cells and TSICreating a compact AC Backup system using fuel cells as DC source!

A transportable Power Backup

Our society and commerce throughout the world today has become totally dependent on reliable communications. This is especially true when violent weather, earthquakes and even volcanic eruptions call for a coordinated response

from the authorities and relief agencies. The continued operation of telecommunications systems and data centres is vital to bring assistance quickly to those who need it. In these situations the mains electricity may be disrupted and existing standby solutions may also be knocked out. To get communications back up and running it would be necessary to transport in a power generator ready to go at a moment’s notice. The power requirement for a telephone exchange or data centre can be large, as much as 50kW. To build a generator

capable of this output yet also transportable presents a significant challenge.

In 2013 the challenge was taken up by CE+T Power, the manufacturer of advanced power sources together with Dantherm Power, a Danish subsidiary of Ballard Power Systems Inc. The two companies teamed up to produce at short notice a 50kW transportable electricity generator unit for demonstration at CIFTIS 2013 – The China International Fair for Trade in Services in Beijing.

The electricity generator was designed to consist of three elements, a high power fuel cell system produced by Dantherm Power, an inverter from CE+T Power and a rechargeable battery bank.

In a fuel cell a liquid or gaseous source material reacts with air directly without combustion to produce electricity. Because there is no flame, boiler or heat exchanger the process is reliable, efficient, quiet and emission free. The ElectraGenTM-H2 fuel cell system produced by Dantherm Power uses hydrogen as the fuel source, which reacts with air to produce electricity and pure water. So the system has strong renewable credentials.

Complete system

The fuel cell alone takes time to start up so cannot alone provide an uninterruptible power supply. This is where CE+T Power comes in. The inverter from CE+T Power ensures that power is available at the output busses continuously irrespective of any interruption to the supply from the mains power grid. CE+T Power is a supplier of inverter solutions to several major fuel cell providers around the world because of the key advantages of its double conversion architecture. For the China Fair exhibit, CE+T Power supplied a TSI Bravo inverter system. The detailed makeup of the CIFTIS 2013 exhibit is shown in Figure 1.

Key facts

�� End user : CIFTIS 2013

�� Location : Beijing (China)

�� CE+T partner : Dantherm Power (Denmark)

�� Solution : 75kVA Modular Inverter System TSI BRAVO 48Vdc/230Vac

12 x 5kW Fuel Cells Blocks

60kW

6 x 48Vdc Battery Banks

60kW

3 x 400Vac Public Grid

48Vdc bus

6kW charger

Load

3 x 400Vac 50kW / 50Hz

DC in

Monitoring

CE+T Power Inverters75kW (60kW)

Figure 1 : System Block Diagram

www.cet-power.com

When power is available from the 400Vac grid the TSI Bravo inverter takes in the AC mains and via a high efficiency (95%) double conversion process delivers clean 400Vac to the load. The CE+T inverter consists of a three pole TSI Bravo system capable of 75kVA/60kW. In the event of a grid failure or brownout the TSI Bravo system instantaneously switches to the 48V battery bank to maintain power and sends a start-up command to the Dantherm Power ElectraGen fuel cell system. When the fuel cells are ready to deliver power, the batteries are switched out and the fuel cells take up the load. Throughout this process the TSI Bravo inverter continues to deliver a stable 400Vac out without a single missed cycle or transient.

The TSI Bravo inverter also manages power delivery to a 6kW external charger to return the battery bank to a full state of charge in readiness for any further interruption, even when the fuel cells are in operation.

The bank of 12 Dantherm Power ElectraGenTM H2 5kW/48Vdc fuel cell units delivers power to the CE+T inverter on a common 48Vdc bus. The fuel cells are supplied with bottled hydrogen at a flow rate of 520 standard litres/min when running at 50kW load and are capable of delivering full power for as long as required.

The hot swappable modular design of the TSI Bravo enables the same architecture to cover outputs from a single phase 2.5kVA up to a three phase unit delivering 225kVA. The dual conversion technology provides high efficiency and 0ms transfer time for seamless switching without flicker or surges.

With its unique features and functions, the TSI topology is a perfect match for any fuel cell application.

Beating the deadline

CE+T Power aims to be flexible in response to customer needs and focus its resources to meet tight lead times. When Dantherm Power committed to exhibit at CIFTIS 2013, CE+T Power allocated manufacture of the TSI Bravo 75kVA system to its factory in Chennai, India. However, the completed inverter system had to be shipped to Dantherm Power’s HQ in Denmark and then on to Beijing. Because of the extra shipping time, CE+T had to manufacture and ship a complex industrial product from scratch in less than one week, a remarkable achievement.

There are two more reasons for which Dantherm Power chose to work with CE+T Power : a perfectly fitting standard product and end-to-end technical support.

Indeed, the Bravo solution did not require any modification to fit with Dantherm Power’s requirements which were full redundancy, hot plugability, visual interface and built-in breakers and switchgear.

Also, CE+T Power technical experts have collaborated with their counterparts at Dantherm Power during the whole process from before the purchase and after the purchase, all the way to support during installation on site in beijing!

“I’am pretty convinced that its possible to find inverters that have the same efficiency and same level in functionalities. But the advantage of [CE+T’s] setup and the reason why we choose [CE+T] was the integrated solution – module based inverters placed on a backplane, easy to replace, communication interface, breakers, connections all combined in one cabinet.”

Morten MadsenElectronics & Control Engineer

Dantherm Power A/S

www.cet-power.com