INTELEC 2014: Highlights from the Conference

INTELEC 2014 LogoINTELEC 2014 was an exciting event that showed that HVDC is delivering everything the technology promises when deployed in real applications. During the conference I was struck by three presentations that discussed the benefits, and challenges, of HVDC deployment.

The first paper described the experiences of an undisclosed Canadian telecommunications operator that upgraded a large central office to 380 V DC power distribution. Interestingly the driver for the upgrade was the lack of physical space: the building didn’t have the capacity to install the additional computers and routers that were needed using the 48 V DC distribution system. By upgrading to 380 V DC, the amount of copper cables required was reduced significantly, and the routing of the power was simplified considerably.

The old 48 V DC systems were not thrown out: they were concentrated in a corner of the central office, using a DC-DC element to provide the 48 V from the HVDC rail (this is the approach we also advise customers to take).

The system was up and running on time, and the operator was pleasantly surprised to see that the increased efficiency of the 380 V regulator showed up in the first month’s electricity bill. Whilst some of the saving might have been due to the inefficiency of the old regulator, the operator was delighted with the op-ex savings, as well as the increase in capacity.

Another operator, this time based in the USA, discussed the operational issues around maintaining a 380 V DC power distribution system. There are many personnel who are familiar with maintaining 48 V systems, but when the voltage exceeds 60 V, and is no longer considered safety extra low voltage (SELV), additional certification is required. Operators therefore need to either retrain and certify the existing maintenance engineers or outsource the maintenance.

The requirements for HVDC, however, are no different to those for AC distribution. Typically operators choose to contract out AC maintenance. Whether they choose to do the same for HVDC remains to be seen, but the fact that the maintenance problem is being considered in such depth shows that there is little question the switch to HVDC will be made.

Finally there was a great discussion about the use of HVDC to distribute power for mobile communications. With the rising demand for mobile data, many urban base stations are becoming saturated. With no additional frequency spectrum available, the only solution is to deploy small cells, an approach that distributes many antennas to reduce the number of cell phones that are connected to any one antenna.

Distributing power to the antennas is an interesting challenge. While using the local grid is convenient, it is not possible to achieve the reliability required for telecommunications systems unless large and expensive backup systems are used. These systems also require maintenance as the batteries have a limited lifetime. A better approach is to distribute power from the central office, which will already have backup, and it turns out that 380 V (distributed as a bipolar supply) is ideal for use with the telecoms twisted pair cabling that is typically insulated to 200 V.

The HVDC voltage minimizes the current, enabling a single assembly that includes the twisted pair and fiber optic cable, which can be easily routed. Some operators have looked at 48 V for power distribution, but it requires a larger conductor to carry the current, making cable routing much more challenging.

These three presentations showed that HVDC is proving to offer a solution to a wide range of power distribution problems, including previously unexplored applications such as distributing power to microcells. There are some barriers to overcome, particularly safety when moving from SELV to HVDC, but users of the technology are finding solutions, and realizing that HVDC presents no more challenges than familiar AC line power. In my view, it’s clear that there is real momentum behind the technology, and we will see a rapid increase in deployments in the next couple of years.

 

To read an interview with Maurizio about his opinion of INTELEC 2014, and the demo in which Vicor participated, click here.

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