Neutral inductive coupling for improved underground medium voltage BPLC

In the underground MV BPLC systems, the inductive coupler has been mainly used being clamped around the MV power cable. But the high current on the MV power line causes the magnetic saturation of the inductive coupler, so the quality of coupling could be gone down. To solve this problem, we suggest that the neutral line of the underground MV power line can be used for the coupling as a communication medium, and we have newly developed a inductive coupler with loss less than 5 dB for the underground MV neutral line and experimentally assessed it. For the purpose of evaluating the coupler, we had constructed the underground MV BPLC test bed that has the 9 repeating points with the 200 Mbps class BPLC repeaters. The length of the test bed is about 836 m. It is located in Ansan-city, Korea. We have measured the transmitted signal attenuation and TCP data rate as the factors of the performance evaluation where the TCP data rate means the data rate over TCP layer. The results measured about the existing inductive coupler and the new one have been compared, and the results measured according to the inductive coupling methods included the neutral line coupling method have also compared. As a result, the suggested coupling method and the newly developed inductive coupler have not only the good performance, but also the cost effectiveness because of the fact that there is no magnetic saturation problem and its small size. Therefore, when we consider the cost effective communication infrastructure for Smart Grid, we can say that the underground MV BPLC system is still attractive.