by Alex Apostolov, Editor-in-Chief

Communications are the key

Distribution Automation is one of the main components of the Smart Grid. There are many definitions that cover different aspects of the distribution automation system, with some even including automation of the engineering, construction, operation and maintenance.


Communications are the key

In this issue of the magazine we are looking at distribution automation from the point of view of the automation of the protection and control of the distribution system.
There are several main areas of distribution automation applications:

  • Fault Location, Isolation and Service Restoration (FLISR) is probably the function most commonly identified as distribution automation. It has a significant impact on the reduction of the number and duration of outages, as well as the number of affected customers
  • Automated voltage and reactive power management helps utilities to manage demand more efficiently, while at the same time improving the quality of power, which is critical for the digital economy
  • Condition monitoring of primary and secondary equipment is another important function that allows the transition from time based to condition based maintenance, resulting in lower maintenance cost and at the same time in higher reliability
  • The requirement for integration of Distributed Energy Resources in the distribution system is very challenging and further complicates the functionality of distribution automation. This is due to the requirements for ride-through of the DERs during the voltage drop caused by short circuit faults, the coordination of the voltage control between the individual DERs and substation based systems, the continuously changing power output and many others

When we think about the implementation of all these distribution automation functions, it is clear that they require real-time exchange of information which depends on the communications.

The communications for distribution automation have to be designed based on the requirements of the application, which will define for example the performance requirements. This will require answering the question “What is the required message transfer time?” If we look as an example at the FLISR application, there are several different sub-functions that are part of it:

  • The fault location and isolation is something that requires a high-speed fault clearing in order to clear the fault, but once this is achieved, the fault location and isolation is typically based on information from line sensors that monitor the current flow and measure the magnitudes of fault currents
  • The fault detectors then communicate the information to other devices in order to isolate the faulted section of the distribution system
  • After the isolation of the faulted section, the next step is the service restoration by closing of normally-open tie switches to neighboring feeder(s). This re-energizes healthy portions of the feeder and restores services to all customers served by these feeder sections from another substation or feeder

It is clear that implementing this distribution automation function relies on communications to achieve the reduced outage time as a result of the initial fault condition.
The experience of FLISR projects by different utilities indicates that reliable point-to-point or point-to-multipoint communication are used for data collection in order to define and implement the restoration strategy. The design of the system will depend on the available communications, the coverage that they provide, the latency of the communications and the FLISR design - with centralized or distributed intelligence.
The investment in the engineering, testing and implementation of advanced, communications based distribution automation systems is paid back quickly as a result of the reduced outage duration and improved quality of service. It requires a vision, a forward-looking thinking and a good understanding of the available IED and communications technologies.

"Vision without action is merely a dream. Action without vision just passes the time. Vision with action can change the world."

Joel A. Barker