Robert Uluski, EPRI, USA

Enhanced Distribution Operating Goals

The distribution system operating goals have always included maintaining a safe environment, providing reliable service (including restoring service quickly when the lights go out), maintaining acceptable voltage, being reasonably efficient, and protecting the assets. While these fundamental operating objectives still apply, the Electric Power Research Institute's (EPRI) R&D activities in advanced distribution applications show clearly that today's utilities are seeking to accomplish much more:

  • Maximize efficiency and reliability
  • Improve system performance
  • Control the growth of demand and promote energy conservation
  • Accommodate as many distributed energy resources (DERs) as possible, and
  • Handle major new loads such as electric vehicle chargers

A fundamental strategy being implemented by an increasing number of utilities to accomplish many of these objectives is Distribution Automation (DA).

What is DA?
Today's electric distribution systems depend on intelligent field devices and control systems to maintain maximum efficiency, reliability and performance while improving safety and protection of distribution assets. These facilities must perform properly in dynamic operating environments due to higher penetrations of distributed generating resources (including renewable energy resources with highly variable output) and new types of loads such as electric vehicle chargers. This dynamic operating environment is especially challenging for existing protection, automation, and control (PAC) facilities, which must adapt to continuously changing operating environment.
Distribution system operators must also be able to deal with a rapidly expanding amount of new distribution system information that threatens to overwhelm the operators. To address this situation, distribution control centers are transitioning from mostly manually operated devices and paper-driven processes, to remotely operated devices and computer-assisted, electronic decision support systems which (in some cases) perform fully-automatic control actions without manual intervention.

Distribution SCADA - The Foundation for the Smart Distribution System
A key enabler for the smart distribution system is the ability to continuously monitor and automatically control distribution field devices located in distribution substations and out on the feeders themselves. This enabler is commonly referred to as Distribution Supervisory Control and Data Acquisition (DSCADA.) Until recently, very few DSCADA facilities were available on the distribution system, especially for portions of the distribution system that are outside the substation fence (Figure 1.)
To enable the smart distribution system, robust and reliable communication facilities are needed to acquire measurement data and to initiate remote control actions. One of the most significant barriers that prevent widespread DSCADA deployment is lack of available two-way communication facilities at the field devices. Distribution system communications are especially challenging due to the wide coverage area, large number of communicating devices, and presence of obstructions. Many utilities are seeking to leverage AMI communication networks and public and private infrastructure (e.g., cellular networks). However, numerous challenges must be overcome, such as overall system security, performance during power outages, and overall data throughput.
Establishing this DSCADA foundational element will enable electric distribution utilities to implement advanced distribution applications, such as Fault Location Isolation and Service Restoration (FLISR) and Volt-VAR Optimization (VVO), which are described below. 

Relion advanced protection & control.
BeijingSifang June 2016