Cybersecurity, T&D, Transmission

A New Approach for Reliable Energy: Underground Substations

Issue 7 and Volume 20.

by Germán Fernández, Belden

Transformer substations are used by energy suppliers to link different voltage levels among generation, transmission and consumers-an integral part of the power distribution process.

But these essential structures are unsightly and often reduce property value.

This is especially true in urban environments where power demand is high but the available space for substation construction is limited.

With the U.S. Energy Information Administration’s predicting global energy demand will rise 40 percent by 2035, how do energy suppliers ensure they are meeting the power requirements of densely populated cities without negatively affecting the communities?

One solution is underground transformer substations.

Supporting German Energy With Region’s First Underground Substation

Mainova AG, one of the largest German communal energy suppliers, was the first to implement this underground substation concept in Frankfurt to accommodate growing energy demands in the densely urban area.

Built 17 meters below street level, Mainova’s substation fulfilled all the functions of a traditional transformer substation while minimizing the need for valuable aboveground space.

Engineers enter and maintain the substation through a small access building, which is much smaller than the footprint of a traditional substation above the surface, and the rest of the space above ground was converted into a garden directly above the transformer.

The resulting greenspace in the city center is a stark, positive contrast to a substation.

Although underground substations are a relatively new concept, the benefits of this friendly and safe solution-reduced impact on the environment and increased safety to the surrounding community-aren’t going unnoticed. But building such an essential structure below street level requires solid infrastructure and a reliable communications network.

Network Design, Implementation-The Backbone for Success

Building transformers underground requires a sound and thoughtfully designed communication network because this network structure is the basis for ensuring reliable, safe, remote management and monitoring of the transformer substation.

To build the substation underground, Mainova AG chose the following design elements:

    Ring topology. Within the plant, the company installed compact RS20 managed open rail Ethernet switches that connected to two MACH1020 backbone ruggedized rack-mount switches for fast Ethernet.

    Network monitoring. A telecontrol system assembled the reports and measurement values from the individual field control devices and transferred them to the control center through the external backbone network, based on MACH4000 with 10G links and Layer 3 routing protocols. Commands from the control center were distributed via the local network to the appropriate field control devices.

    Redundancy protocols. Redundant communications for the local-area network was guaranteed by the media redundancy protocol (MRP) according to IEC62439, which optimizes reconfiguration time for ring topologies in the case of a network outage. For the backbone network, linking the substation with other substations and dispatching center Layer 3 redundancy protocols as Virtual Router Redundancy Protocol (VRRP) are two common methods used to maximize network availability.

    Network management systems. To effectively manage the substation and its critical data, a network management software that provided real-time, user-friendly topology maps was used. This allows the network administrator to see how and where all components of the network were connected at a glance, including any unmanaged switches and hubs. With management software, network administrators can configure hundreds of devices simultaneously with just a few clicks of a mouse, which helps administer routine maintenance tasks, such as changing device passwords to protect against cyberattacks.

At 17 meters below street level, Mainova’s substation fulfills all the functions of a traditional transformer station while minimizing the need for valuable aboveground space.

When designing an underground substation, equipment should be able to reliably transmit data, even under harsh environmental conditions. Although direct exposure to the elements is eliminated, the compact nature of underground construction presents new challenges. The temperature profile of the environment, permitted operating temperatures and heat dissipation can challenge the reliability and integrity of the cables, switches and routers involved in the transmission and distribution process, making it critical that the substation equipment is designed to withstand these tough underground conditions.

Products with high transmission rates and large bandwidth will guarantee the quickest possible processing of large data volumes and provide the highest level of reliability, availability and security when operating underground.

Robust and rugged network management software, for example, facilitates the monitoring of all systems throughout the network and can provide a topology map that enables network administrators to see at a glance how and where all components of the network are connected.

Switches specially constructed for each level of the network can maximize network uptime when developed with strong resistance to shock, vibration and electromagnetic interference.

Underground substations easily could become the future of electricity in urban areas, giving customers the reliable energy they need while minimizing communities’ carbon footprints.


Germán Fernández is the vertical marketing manager of power generation and transmission and distribution at Belden. He has 15 years of experience in the electric power industry, specifically pertaining to industrial Ethernet networking and telecommunications technologies. Fernández has managed power projects worldwide as a system integrator and brings a deep understanding of cybersecurity needs for electric power utilities. He is also a member of the Cigre Working Group D2.40. Reach him at german.fernandez @belden.com.