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Distribution Overhead Line Monitoring with LEM’s ART Rogowski coil
New line current sensors allow utilities to monitor their overhead distribution lines to
maximize their capacity and prevent clearance violations thus improving reliability and
efficiency of the MV Distribution Grid.
The High Voltage transmission grid is already highly automated and monitored through SCADA
and Energy Management Systems. In contrast, the Medium-Low Voltage distribution grid has
very limited monitoring and control. Why? - More often than not, Utilities fail to monitor their
many medium voltage substations, this is due to the expense of retrofitting with today’s solutions
and of the time it takes to plan and build. The implementation of traditional substation monitoring
requires complicated engineering, this includes the use of remote terminal units with new
conduits, wiring to relays and current transformers. Engineers must schedule outages to
disconnect the feeders, which takes time and may only be possible during low power
consumption needs. Once the hardware has been installed, the utility has to program and
integrate all the hardware into a complex SCADA system, which is a significant and difficult
challenge for many utilities. There must be a better way.
Below the feeder level, remote monitoring is absent with the exception of customer billing meter
points where smart meters are becoming prevalent to read, monitor and control. However, these
smart meters are only collecting and communicating Voltage, Current , Power, Reactive Power,
S, Energy data rather than power quality data sets like Cos (Phi), Total Harmonic Distortion,
flicker, voltage dips, transients, waveforms, time series etc. The smart meter does not collect a
lot of data outside of its billing focused function. Substations and distribution power lines are two
of the most valuable assets for utilities that require crucial power flow data to provide the most
reliable service.
The most relevant data in the distribution grid is about the location and cause of faults and non-
fault events, high-impedance faults, consumption peaks, handling distributed renewable energy
and EV charging, feeder outages, and many others – all high-value data that is not addressed by
today’s systems.
Now monitoring overhead power lines has been made possible faster, easier and cheaper with
new Internet of Things telecom networks like NB-IoT and LPWAN.Thanks to a line sensor (1),
installed between two MV poles (2), the grid operator can visualize, in real-time, the current flow
in order to optimize the power line capacity to distribute more electricity. The wireless line sensor
(1) sends data over a telecom relay (3) to a secured database in the cloud (4) or on premise.
The energy management platform (5) can regulate, alert and notify the maintenance team if
needed. New line sensors are now using the LEM Rogowski coil ART (A) to measure the current,
detect line aging depending on the level of current, and prioritize line capacity.
A. LEM ART
1. Line Sensor
2. MV Power Lines
3. Telecom relay
4. Cloud and database
5. Energy Management
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Before without visibility about the grid, the generated renewable energy distributed through an
overhead line could be overloaded (red). Thanks to the three-phase line sensor system, the
extra power in one of the line can be re-distributed to the adjacent lines (black) therefore
reducing the initial line (blue) capacity to an acceptable level. Overall, the capacity output of the
power grid is then maximized (fig. 1).