The Smart Grid is a system of intelligent devices distributed across electrical power networks, combined with communications networks which connect the devices to each other and to the utilities’ central monitoring and control stations. These intelligent networks monitor and control every functional aspect of the transmission and distribution systems themselves, including fault management, power quality and switching functions. Smart meters installed at customer points of connection automatically monitor energy usage in real time, both for billing as well as energy management purposes. Demand side management devices installed within customer premises also allow the Smart Grid to automatically manage customer loads at critical periods to avoid blackouts, brownouts or other undesirable conditions. In an environment of Distributed Electrical Resources (DERs), the Smart Grid facilitates a seamless management of a diversity of electrical generation or storage resources that can be switched or routed over the network for optimal results.
The Smart Grid is generally viewed as the network model of the future, and the basis of the emerging green electrification infrastructure. The communications networks interconnecting all of the Smart Grid elements can be implemented in a variety of ways. One approach has been to use the power lines themselves as a transmission path, allowing utilities to operate their Smart Grids over a completely dedicated communications system, independently of any public networks. This approach is known as Power Line Communications (PLC).
In spite of the advantages offered by PLC networks, many of the utilities employing this solution have been experiencing issues with their Smart Grid communications due to high frequency interference on their power lines. The sources of this interference are the complex electronic systems at utility stations, the power electronics and other digital devices on the DERs, and even the distributed accumulation of Smart Grid devices themselves, as well as various switching and other transients on the networks. (Analysis of noise in broadband Powerline Communications (B-PLC) in frequency range of 150kHz–30MHz | IEEE Conference Publication | IEEE Xplore) There are many advantages to large networks of interconnected grids, but this also creates a large propagation medium for interference sources all over the networks. Similar issues exist for utilities which simply route their Smart Grid communications over public networks, since those facilities can also become part of the EMI propagation path. Individual devices can also simply be impaired by local EMI conditions in proximity to power electronics or other nearby sources, or by interference that has been delivered over the grid from other points on the network. Research groups have demonstrated that Smart meters can be, and have been, adversely affected by ambient EMI effects, causing meters to report high usage levels when there has been little or no energy consumption, or reporting little or no consumption when usage has in fact been high. (Misreadings of Static Energy Meters due to Conducted EMI caused by Fast Changing Current | IEEE Conference Publication | IEEE Xplore)
These issues can be avoided, remediated or mitigated by developing adequate electromagnetic characterizations of the overall networks and their subsystems, and by implementing appropriate design, layout, filtering, shielding and grounding strategies throughout the network. The Smart Electric Power Alliance (SEPA) is an association of utilities, engineering groups and other stakeholders. Their recommendation is that before any Smart device is deployed in any network environment, that environment needs to be electromagnetically characterized to see whether the device’s EMI specifications are adequate. When that is not the case, additional EMI mitigation strategies would need to be put in place to sufficiently enhance the device’s immunity in those environments. (Electromagnetic Compatibility (EMC) Assessment, Testing and Mitigation | SEPA (sepapower.org))This reaffirms the fact that even though a device receives a satisfactory EMI rating in isolation during certification testing, it may still behave in unexpected and unsatisfactory manners when placed within certain systems or environments.