Channel Modelling and Channel Selection for Broadband PLC on Medium Voltage Overhead and Underground Lines

Transcription

1 Channel Modelling and Channel Selection for Broadband PLC on Medium Voltage Overhead and Underground Lines 9 th Workshop on PLC (WSPLC 15) September 22, 2015 Klagenfurt, Austria Vamsi Krishna Marri, Stephen Dominiak Lucerne University of Applied Sciences & Arts (HSLU) Horw, Switzerland Mikko Maurer Ormazabal Maegenwil, Switzerland

2 Agenda Introduction to Swiss utility MV distribution network Some of the challenges for the large scale BPL deployment on a MV network BPL measurements and the channel modelling Channel selection procedure WSPLC

3 Eco Meter Medium Voltage (MV) distribution network Smart Grid Landscape Control Center Central Generation Medium-Voltage Distribution Low-Voltage Access Electric Meter Smart Home High-Voltage Transmission Distributed Generation T F Vehicle to Grid (V2G) Focus on Broadband Power Line Communications (BPL) within the Medium Voltage (1-36 kv) distribution network BPL technology is based on the OPERA specification (2-30MHz) MV network consists of Primary Substations (PS), Secondary Substations (SS) and the cables/wires which interconnect them The main applications targeted for MV-BPL are AMI and grid monitoring/automation Several technical and practical challenges exist for providing a large-scale BPL deployment WSPLC

4 Network characteristics of a Swiss utility The general geographic topology of Switzerland consists of a collection of small urban cities with large rural areas in-between Network analysis of a Swiss utility shows the same topography is carries over to the grid topology and found the following important characteristics: The network consists of roughly 50% underground cables and 50% overhead wires Many links between neighboring transformer stations are a mixture of both overhead wire and underground cable Overhead wires and underground cables can be found in all regions of the overall network Link type distribution between two neighboring Transformer stations WSPLC

5 Challenges for the BPL deployment Based on the Swiss utility MV network analysis, two challenges are identified: Determining channel model for the different types of links: overhead, underground and mixed (overhead + underground) Performing channel selection for a BPL cell which consists of both underground and overhead links WSPLC

6 Channel model Understanding and defining a model of the transmission channel is the foundation for defining a deployment concept Several in-situ measurements were conducted on the Swiss utility and three different models were developed for three different link types Legend Coax Grounding Wire AC Mains Ethernet TNC/ BNC Adapter TNC/ BNC Adapter Portable Generator BNC Connector Clamping Screw Portable Generator AC Mains Connector RJ45 Connector Ground Wire (TBD m) Ground Wire (TBD m) 50m Reel 50m Reel Measurement Setup A 50Ohm Coax (3 m) Lightning Arrestor 50Ohm Coax (TBD m) 50Ohm Coax (TBD m) Lightning Arrestor 50Ohm Coax (3 m) Measurement Setup B Grounding Pole Grounding Pole General measurement setup for the overhead lines WSPLC

7 Findings from the channel model Channel attenuation: Underground cables: attenuation increases significantly for increasing frequency Overhead wires: attenuation increases slightly for increasing frequency Polyethylene (PE) cables provide much better communication than Paper Insulated Lead Covered (PILC) cables Noise P.S.D.: Noise decreases exponentially versus frequency Overhead wires suffer from a higher absolute noise value Max link length Overhead: > 2Km Underground: Up to 1Km Overhead attenuation model Overhead noise model WSPLC

8 BPL network structure Hierarchical network architecture is the key to providing scalability for a large network The total network is divided into several clusters called BPL cells One of the nodes in each cell acts as a master to the cell and has a connection to the backhaul network Each cell can be operated with only one frequency band (channel) Multi-channel solution: Necessary guard distance must be upheld between the cells which operate on same channel in order to mitigate the interference In order to increase the coverage capability more than one channel is required Use of more than one channel enables a higher channel reuse which is the similar concept used in the cellular wireless networks The channels should give optimum performance for the BPL cells which consists of mixed links WSPLC

9 Channel selection procedure Output P.S.D. Channel Attenuation Model Noise Model SNR OPERA Model PHY Data Rate Available Subcarriers EMC Requirements Application Performance Requirements Optimum Channel Selection (Max. Coverage) Network Coverage Analysis Max. Supported Link Length Threshold Evaluation WSPLC

10 Findings from the channel selection analysis The different characteristics of overhead wires and underground cables lead to conflicting optimum results In order to maximize the overall BPL coverage considering a cell with mixed links, it is necessary to reach a compromise in terms of channel selection between overhead wires and underground cables The results of the analysis have found that the use of the following channels can maximize the coverage: 2MHz 9MHz 10MHz 19MHz 20MHz 30MHz WSPLC

11 Conclusion Based on the network analysis conducted on the Swiss utility MV grid several challenges have been identified Channel model has been realized for the different links: overhead, underground and mixed Optimum channels are selected for the cells with mixed links The selected channels have been verified with a network simulation platform created based on the OPERA standard WSPLC