Power Line Carrier Communication from 11kV to 400V 2

[Jennett]

Can power line carrier communication (PLCC) be used to transfer a signal from an 11kV power system to a 400V power system? The application I am investigating is to see if a blocking signal can be sent from an 11kV CB to a distributed generator at 400V. What would the limiting factors be in this scenario? I.e. Does the voltage change cause problems for the PLCC? Does the distance of the line limit over where this could be applied? Would noise be an issue in this application?

 

[gvasiliou]

Most PLC technologies limit themselves to one set of wires (such as premises wiring within a single building), but some can cross between two levels (for example, both the distribution network and premises wiring). Typically transformers prevent propagating the signal, which requires multiple technologies to form very large networks. Various data rates and frequencies are used in different situations.

A number of difficult technical problems are common between wireless and power line communication, notably those of spread spectrum radio signals operating in a crowded environment. Potential interference, for example, has long been a concern of amateur radio groups.

http://en.wikipedia.org/wiki/Power_line_communication

 

[DTR2011]

Broadband over Powerline (BPL) was considered and tried a while back. Going through transformers was an issue, but I believe this was resolved by shunts. BPL fell by the wayside in the last few years.

Have you considered other methods such as radio / microwave, fiber? How far is your run between 11kV and 400V?

 

[Jennett]

I am trying to determine a low cost method that could be used to apply this blocking scheme. Any of the traditional techniques e.g. radio, microwave and fibre used in HV power systems would be too expensive. Also, I don't need the same level of security that would be required in an HV intertripping schemes. I am looking for a communication scheme that could make use of existing infrastructure. I thought PLC might provide that solution but if it requires shunts to be installed on the transformers I don't think it would be viable.

The run would be variable depending on the length of the feeder. The communication system would need to communicate between the circuit breaker at the start of the feeder to homes on the LV spurs off the main feeder.

 

[DTR2011]

I think the biggest problem will be around you 11kv/400V transformer, but if you can get the signal onto the 400V level (shunt/other method) it is fairly standard PLC. Either way you choose to do it, you need to couple and decouple the signal on the line and that requires equipment at all points of DG.

What kind of blocking signal is this? I have seen many which require that if the 11kV breaker trips and aux contact from 11kV CB goes to feeder breakers to trip them, or prevent close. This is generally accomplished via point to point wiring, however the distances are short. When you mention that security is not so important, do you have confirmation for the grid operator that this is acceptable? There are worker safety issues regarding dumping all sources of energy, if the grid operator needs to do emergency repair work, etc.