Internet-of-Things in Low Voltage Electricity Grids

Abstract: When evaluating future technologies for smart metering and automatic meter reading (AMR) E.ON Elnät Sverige AB has set up a pilot to test a communication technology supplied by Connode AB. Connode have developed a mesh radio solution based on 6LoWPAN, IPv6 over Low Powered Wireless Personal Area Network. By using this technology the communication unit on every meter is acting as both receiver and sender of IPKbased communication packets. The meters are aware of the other meters around them and automatically set up the best way to send a message. If two meters do not have a direct communication path to each other the message will be relayed via other meters until it reaches its destination. These meters will create a wireless network that covers a large area of the E.ON test site Hyllie in Malmö. Connode has also developed a radio card that makes it possible to connect an embedded Linux platform, Intel Edsion, to the mesh network. By having this computer connected to the wireless network from the meters, this will enable a range of use cases within smart grid technologies taking advantage of using distributed computing in the low voltage grid. This thesis has investigated what use cases this technology can be used for. Some of the use cases defined were also implemented by developing two demonstration boxes. The demonstration boxes made it possible to implement the use cases without having an actual grid to test on. The demonstration boxes represent a facility and a substation. In each box there is an embedded computer with a mesh radio communication module. The embedded computer has all grid information via the I/O from the demonstration boxes to be used in the use cases. The use cases that were defined were among others, antiKislanding protection, prioritized automatic disconnection, substation controller and demand response controller. Of these the ones clearly implemented were the antiKislanding protection, prioritized automatic disconnection and the substation controller. The following was performed during the thesis. • Interviewing E.ON employees • Defining use cases • Design of simulation platform for use cases • Construction of simulation platform • Development of software for simulation platform • Evaluation of 6LoWPAN and Connode’s implementation for usage in smart grid applications. Using distributed computing in smart grid applications is clearly a very promising way to handle the future complexity of the modern grid. But it is still the communication technology that will be the crucial part of the solutions since some use cases will depend on high data throughput and transport integrity. This can somewhat be overcome by optimizing the architecture of such solutions but still for larger deployments the communication is the limiting factor. The Connode solution seems very promising, but there are a few issues that are in the way when planning to use the technology for a larger implementation of smart grid. It needs to be stressed that the Connode solution of connecting embedded computers is just for development use and not for production, but some other factors are still in the way. One major issue is the separate IP address that the computer gets that is separated for the meters IP addresses. This makes the solution server unaware of the computer and separate systems must be implemented to be able to use the computer in distributed intelligence architecture. It is also needed to implement all the security features that is already implemented in the metering solution, the embedded computers are not able to use the same features from the Connode server. Also it is not possible for the distributed computers to talk directly to the meters as they must go via the Connode server. At last it was seen that for many use cases a full embedded Linux distribution might be somewhat excessive.