In this paper, a test field of high-data rate PLC using overhead medium voltage power line (MV BPLC) for applications to automatic meter reading (AMR) and distribution automation system (DAS) is introduced. It was established in Jeju island, Korea and 8.2 km long. For the MV BPLC, a MV coupler for BPLC with internal impedance matching transformer was developed. For repeating, techniques of both time division (TD) and frequency division (FD) were properly used. There were strong impulsive noises caused by lightning arresters. The impulsive noise degrades severely performance of MV BPLC because the impulsive noise gives direct influence on data signal. To solve the problem of the impulsive noise, the lightning arresters that are noise sources were found using inductive coupler for medium voltage and replaced with new ones. Finally, we found that the system has more than 2Mbps TCP data rate and can be used as a communication network for AMR and DAS.

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 5dB 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 200Mbps 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.

-Energy storage system connected to the grid has two functions such as the surplus power of a grid is stored in batteries or the energy stored in batteries will supply to the grid when the grid needs. The battery energy storage system consist of power condition system (PCS) for power supply and battery conditioning system (BCS). Lithium-ion batteries are mainly used. In this paper, the battery energy storage system connected to the grid described. The configuration of the 2MVA class power control system using water cooling and battery system are presented. And control method for the system and the output filter design method are proposed. Experimental verification of the proposed system is provided with 2MVA PCS and 500kWh BCS.

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