Last mile connectivity challenges in Smart Grid

Automatic data collection from utility energy meters (HT, LT and consumer) is the first step towards making the power grid smarter. A complex network of these meters all the way to the substation is called Advanced Metering Infrastructure (AMI) and the last mile of this network is called the Automated Meter Reading (AMR) network.

This paper describes a number of technologies that can be utilised in setting up an Automated Meter Reading network in India and the challenges involved in this process. The establishment of Smart Grid is at an advanced stage in some other countries of the world. This paper also tells which of these technologies are selected by these countries and the reasons for their selection with respect to geographical and infrastructural factors.

The paper describes both wireless and wired technologies and also compares the advantages and disadvantages of both. In setting up wireless networks, ensuring a sustained connectivity is one of the biggest challenges because of a wide variation in the location of meters in different localities of the same area. In this paper, various factors like the frequency band (2.4 GHz or Sub-1 GHz), network topology (peer to peer, star and mesh networks) and various standards like Zigbee, WM-Bus, WiFi are introduced and compared. This paper illustrates the steps that can be taken to ensure continued connectivity.

For wired connectivity, power line communication is the only viable alternative for AMI. In power line communication, the noise generated by different loads on the power line and the dynamic changes in the line impedances is the major challenge. This paper shows the latest advancement in PLC technology which makes the use of OFDM modulation as compared to SFSK which was used in yesteryear installations and explains how it helps in addressing the challenges mentioned earlier. This paper also gives an update on the standardizations that are happening and being followed worldwide.

Given the diversity of urban planning architectures and geographical and infrastructural differences at various places in India, it may be possible that instead of selecting a single technology, a hybrid AMR network has to be designed. This paper also describes the challenges involved in commissioning of such networks and what steps can be taken to make these networks more reliable.