The implementation of “distribution automation” within the continental U.S. is as diverse and numerous as the utilities themselves. Particular strategies of implementation utilized by various utilities have depended heavily on environmental variables such as size of the utility, urbanization, and available communication paths.
The current level of interest in distribution automation is the result of:
• The maturation of technologies within the past 10 years in the areas of communication and RTUs/PLCs.
• Increased performance in host servers for the same or lower cost; lower cost of memory.
• The threat of deregulation and competition as a catalyst to automate.
• Strategic benefits to be derived (e.g., potential of reduced labor costs, better planning from better information, optimizing of capital expenditures, reduced outage time, increased customer satisfaction).
While not meant to be all-inclusive, this section on distribution automation attempts to provide some dimension to the various alternatives available to the utility engineer. The focus will be on providing insight on the elements of automation that should be included in an scalable and extensible system.
The approach will be to describe the elements of a “typical” distribution automation system in a simple
manner, offering practical observations as required.
For the electric utility, justification for automating the distribution system, while being highly desirable, was not readily attainable based on a cost/benefit ratio due to the size of the distribution infrastructure and cost of communication circuits.
Still there have been tactical applications deployed on parts of distribution systems that were enough to keep the dream alive. The development of the PC (based on the Intel architecture) and VME systems (based on the Motorola architecture) provided the first lowcost SCADA master systems that were sized appropriately for the small co-ops and municipality utilities.
New SCADA vendors then entered the market targeting solutions for small to medium-sized utilities. Eventually the SCADA vendors who had been providing transmission SCADA took notice of the distribution market.
These vendors provided host architectures based on VAX/VMS (and later Alpha/Open- VMS) platforms and on UNIX platforms from IBM and Hewlett-Packard. These systems were required for the large distribution utility (100,000–250,000 point ranges). These systems often resided on company owned LANs with communication front-end processors and user interface attached either locally on the same LAN or across a WAN.