GE Digital Energy : Industry Solutions : Distribution Automation

Advanced visualization technologies enable the efficient recovery of distribution systems utilizing fault isolation, sectionalization and power system restoration capacities within our wide range of distribution assets, controllers, and high accuracy measurement devices. Our high speed wireless capability provides peer-to-peer communications, enabling distribution utilities to make intelligent decisions, enabling fast and efficient responses to service interruptions.

Most distribution utilities around the world have a minimal or no monitoring on the main or lateral feeders. Early warning for over-current and earth fault detections as well as downstream faults and outages will improve information handling. Efficient fault detection will greatly enhance distribution grid reliability, reducing restoration time drastically from several hours to a few seconds or minutes.

Distribution reliability indices of CAIDI, SAIFI, SAIDI, etc. and service quality performances are thereby greatly enhanced. The figure below demonstrates how monitoring data on a distribution network can reduce the fault location time from 1 to 3 hours to just a couple of minutes. Monitoring enables the utility to save on lost man-hours as well as lost revenue, improving their performances, reliability and profitability.

A key driver and measurement of utility effectiveness is in the reliability of power to its customers. As many faults on overhead distribution lines are transient in nature, reclosing at the substation and installation of mid-line reclosers/switches can improve a utilities SAIDI reliability index by up to 24%. When permanent When permanent faults occur on overhead lines, having feeders with increasing degrees or automation can greatly enhance distribution grid reliability and reduce restoration of unfaulted segments from several hours to a few seconds or minutes. A key component of these automation schemes is intelligent controllers that can integrate with FDIR systems through sharing local information and accepting control commands.

Utilities face a difficult challenge having to dynamically balance the load scenario between customer demands and available generation capacity. Adding to the challenge is the ever changing consumption patterns due to factors such as day of the week, time of day, season, temperature and Power Factor from connected loads.

Maintaining an efficient and reliable distribution network is critical to a utility’s operation. Meeting this challenge requires voltage regulator controller and capacitor bank controllers working in unison.

These devices can operate as part of an integrated Volt/VAR Control (IVVC) scheme or as a Centralized Volt/VAR control (CVVC) system.

The IVVC or CVVC system works to achieve two key objectives:

Optimize Voltage - through ‘Conservation of Voltage’ that leads to reduced demand, that may result in decreased generation up to 6%.

Increased efficiency - through improved power factor and reduced VAR which helps to reduce power line losses.

There are a number of approaches used by the industry to deliver dynamic line rating:

Distributed weather and substation load data approach: monitors the influences that impact the conductor temperature, such as weather and load, and couples these with the static factors such as conductor size and type
Distributed load and conductor temperature approach: measures the temperature and load of the conductor directly on the conductor distributed throughout the circuit
Hybrid approach: uses a combination of distributed weather, load and conductor temperature data

The combination of using distributed weather data, load and conductor temperature is a cost effective and comprehensive way to deliver dynamic line rating. It enables the rating algorithms to become dynamic in their own right, as the conductor temperature measurement provides the potential for a calibration input to the algorithm to correct the thermal changes to the static values of the conductor over time, and uses the weather data to facilitate short term forecasting of rating. The conductor temperature input also delivers further value, as it delivers a line sag/clearance application.

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Identifies additional capacity that can safely pass through the line
Determines incremental line sag and clearance from the line to the ground
Incorporates effect of cooling from wind and terrain on different parts of the line

Enhanced line monitoring systems capture and analyze data from multiple distributed locations, and notify and display this information to system operators and field crews. The information allows operators to make timely decisions and arms field crews with the information they need to quickly find and fix the faulted feeder. This enhances the overall efficiency and reliability of overhead line power systems.