1. The Role of Intelligent Line Sensors
In Grid Modernization
Background
Energy distribution and management are increasingly complex with challenges from extreme
weather, changing power demand patterns, vegetation encroachment, and higher customer quality expectations.
To make matters more challenging, according to the U.S. Energy Information Administration (EIA), the
United States’ power distribution infrastructure is aging at a critical rate with approximately 70% of
distribution lines at least 25 years old.
While standard faulted circuit indicators (FCIs) or fault passage indicators (FPIs) have served
electrical power distribution systems well in the past, the complexity of today’s power grid requires
more advanced technology that goes beyond simple indication of fault presence. Optimizing the
health of the modern grid and delivering safe, reliable power requires use of intelligent sensors
capable of monitoring, notification, and data gathering.
2. Moving Beyond Fault Indication
Today’s utilities are faced with a convergence of challenges. Aging infrastructure, integration of
DERs, extreme weather, wildfire risk, and cybersecurity concerns all necessitate a level of visibility
and actionable insights which FCIs cannot provide. Whether related to installation of behind-
the-meter generation resources, targeted maintenance and vegetation management efforts, or
mitigating the ever-growing threat of cyber-attacks, a smart grid requires more than fault indicator
monitoring capabilities.
Beyond knowing when a fault has occurred via an FCI or FPI device, utilities must be equipped with
system visibility and data that allows for more precise fault analysis, improved load management,
and disturbance analytics which can enable fault prediction and outage avoidance. Intelligent line
sensors allow utilities to proactively improve power reliability with better SAIDI, SAIFI and CAIDI
values, while also addressing the evolving system needs of a modernized grid.
3. Reliability and efficiency-focused utilities opt to use intelligent line sensors for not only enhanced
system conditions monitoring, but also the valuable historical and real-time data collected by these
sensors. Four of the most beneficial data use cases are fault detection, ADMS integration, load
logging and asset management.
USE CASE 1: ADVANCED FAULT DETECTION, NOTIFICATION, AND ANALYSIS
Utility decision-makers must balance the cost of preventative measures taken to avoid critical
equipment loss against the cost and service implications of reacting to all problems. Industry-
leading utilities leverage Sentient Energy intelligent line sensors to pre-emptively identify and
correct problematic circuit conditions before they result in service interruptions. Line sensors
provide advanced fault detection, reporting, and accurate phase identification. In the event of
a service interruption, line sensors provide fault detection and accurate fault magnitude data to
facilitate timely and efficient fault location, isolation, and service restoration.
Sentient Energy’s overhead and underground intelligent line sensors detect and communicate
the most important system-wide fault information directly to utility first responders. Detecting
momentary and sustained interruptions caused by faults and other anomalies, the line sensors
notify real-time operations groups either by email or through direct integration to the utility’s
Operational Systems (e.g., ADMS/SCADA system) using DNP3, IEC 60870-5-104 or REST APIs.
To reduce crew patrol time and shorten the overall restoration process, accurate fault location is
needed. Intelligent line sensors provide the fault current and fault type information (line to ground,
line-to-line, etc.) necessary for Sentient Energy’s Ample Analytics Platform or the ADMS system
to effectively estimate fault location.
4. In a recent T&D World webinar Sentient Energy customer partner, Alabama Power Company,
reported multiple benefits realized by using intelligent line sensors to provide detailed fault
information to the ADMS as part of their fault location, isolation and service restoration schemes:
• Fault location halos resulted in patrol distance reduction of 88%,
from 3.7 miles to 0.4 miles (6 km to 700 m)
• More cost and time efficient to install sensors than upgrade relays
• Sensors can report fault data without a breaker trip
• Ample software can be used by reliability engineers
• Firmware meets cybersecurity standards
5. In systems where backbone distribution lines traverse limited access areas, like those shown in
Figure.1 below, Sentient Energy line sensors dramatically reduce crew patrol time by directing
crews to the last section of the circuit where sensors have detected the fault. This eliminates the
need to patrol the entire circuit looking for “blinking LEDs,” a fact especially critical when those
LEDs cannot be readily located. The yellow halo shown in Figure.1 indicates the last sensor that
detected the presence of fault current, as well as the magnitude of fault current, and the phases
affected by the fault. The GPS location of the highlighted sensor is attached to the fault notification
which allows repair crews to be dispatched to the faulted section of line.
Figure.1 – Fault Analysis
location view from Sentient
Energy’s Ample Analytics
Platform
For additional engineering
analysis, fault waveforms,
sampled at 130 samples
per cycle for 60Hz systems,
are automatically captured
and downloaded to the
Ample Analytics Platform.
This allows engineers and
operators to review the event
if they want to gain more
insight into the cause or if
they suspect a mis-operation. The waveforms can be compared with other sensors or relays to gain
a clear picture of the grid operation which supports short and long-term planning, and verifications of
relay settings and protective device function.
6. In the waveform shown in Figure.2 below, fault current was detected that resulted in a recloser
opening and closing back into the fault. After reclosing the fault current persisted at a lower
magnitude but the recloser did not open, and the fault eventually burned out.
Figure.2 – Fault Analysis, fault event waveform data from
Sentient Energy’s Ample Analytics Platform
7. Faulted Phase Identification
By combining the current, electric field and GPS synchronization, the intelligent sensor automatically
detects the phase it is installed on. Utilities can use this information to correct any database errors
that affect all operations technology systems. Phase identification information is also used for
tracking continuous distribution network feeder connectivity, as construction and restoration may
lead to phase misidentification anomalies.
