Sumitomo Electric and TEPCO PG have jointly developed a remote monitoring system using G3-PLC communication for underground power transmission lines.
G3-PLC is widely used as last mile communication technology for smart metering globally. For example, in France, over 30 million smart meters communicate using 100% G3-PLC. Although originally designed for smart metering, G3-PLC is currently used in many other applications such as smart grids and grid diagnostics, (public) lighting solutions and HVAC applications, machine diagnostics and railway control systems.
Globally more than 50 million G3-PLC devices are in operation in over 30 countries. Benefits of G3-PLC: There is no dependency on a telecommunications or network operator, lower cost as it uses the existing cables (which saves on infrastructure costs) and there are no fees for licenses, telecommunication or data transmission to be paid. G3-PLC facilitates long-range communication, has high indoor penetration and enables enhanced grid operations as G3-PLC is naturally connected to the grid.
Recently a unique and new application has been added. Sumitomo Electric and TEPCO PG have jointly developed a remote monitoring system using G3-PLC communication for underground power transmission lines.
Underground cable networks considerably reduce network outages and have lower transmission losses but the maintenance cost is high compared to overhead systems. In underground systems transmission faults are rare, but the fault point is hard to locate and the repair is not easy. With the monitoring system based on G3-PLC faults can be located much more easily, considerably reducing the maintenance cost and eliminating the need to lay a new data communication line.
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In their current solution, Sumitomo and TEPCO PG successfully built a sensor network using G3-PLC which uses the shield layer of an underground power transmission line for communication. Point-to-point communication with G3-PLC exceeds 3km. This remote monitoring system for underground high-voltage power transmission lines of 66KV or more has been verified and adopted by TEPCO since July last year.
With this system, the sensor data:
- is transmitted along the high voltage line;
- is collected at a relaying point and relayed above ground;
- is transmitted to the cloud server for data storage by using existing above-ground communications means, such as cellular.
The system eliminates the need to lay a new data communication line, building a highly reliable sensor network at low cost.
Monitoring devices communicating from inside a manhole have not been deployed so far, because laying additional communication lines is expensive and radio waves cannot reach the outside. Sumitomo Electric has developed a monitoring system that utilizes G3-PLC with the metal shielding layer of the existing power cable as the transmission line, which is designed to:
- Capture information from sensors for displacement, spilt oil, temperature, water level etc. that are required for cable maintenance;
- Capture and transmit image data to monitor the internal situation;
- Collect sensor information on a cloud server for analysis and improvement of O&M efficiency and preventive maintenance.
This is a perfect example of how the cost for a reliable communication infrastructure can be kept to a minimum by eliminating the need for laying new data communication lines
The G3-PLC Alliance believes that in the future, digitalisation utilising various IoT sensor devices is expected to greatly contribute to the sophistication of O&M of underground power transmission lines. G3-PLC will make it easier to build a sensor network and provide low cost and reliable communication for this application. The recently introduced G3-PLC Hybrid solution which uses PLC next to RF communication enhances the capabilities of G3-PLC for these types of applications.