Private LTE 450 MHz wireless network for MV Teleprotection

(DSO) are looking for resilient communication solutions. Copper products capable of operating in local black out are being phased out. Furthermore, the emergence of numerous services and applications, each with distinct needs, is driving the demand for greater throughput as well as diverge latency constraints. Therefore, the increasing need for IP based systems is opening a new era for Utilities’ telecommunications. And the interdependency between DSOs and these systems is increasing over time with the development of smart grids.

Although, the Mobile Network Operators (MNOs) are being used for many system communications, they are limited in terms of resiliency for constrained usages. They are sensitive to power failure. The installed backup, if it exists, rarely outpaces 30 minutes when the power goes down. This is mainly to avoid untimely restarts for short electricity failures.

Thus, it is a limited solution for DSO communication systems that requires a resiliency of at least 48 hours. A high resiliency, therefore, is a key characteristic the IP-based system must provide. However, deploying a proprietary/dedicated fiber optic network by DSO is not an affordable solution.

Hence, the usage of private mobile wireless is gaining traction in the Utility world, especially the one based on the Long-Term Evolution (LTE) in 450 MHz frequency band. It is a 4G standard edited by 3GPP and with a growing ecosystem under the umbrella of the 450 Alliance.

This type of radio network leverages the favorable propagation characteristics of lower frequencies, i.e., wide-area coverage and penetration. Hence, it is anticipated that a lower

CAPEX will be incurred in deployment, making it a more cost-effective solution.

The LTE 450 MHz could offer a robust and versatile communication backbone for DSOs. It can ensure, in all cases, the dialog between Remote Terminal Unit and the Supervisory Control and Data Acquisition system (SCADA). It is also a solution to connect field crew to the central office or to establish communication between these crew members. This private radio network necessitates a significant investment; it becomes imperative to grant the operational value derived from these deployments. In this context, EDF’s R&D has reviewed the potential of such a radio network to meet the requirements of Medium Voltage teleprotection in island energy systems as a demanding application. The later encompasses functions like remote protection and emergency disconnection of power plants connected to

MV grids, which needs a very low latency, high reliability, and determinism to achieve fast and accurate fault clearance.

Milliseconds are therefore highly critical in preventing extended outages or equipment damage.

The paper exposes then the telecommunications aspects and constraints in the context of MV teleprotection. It analyses the 4G LTE 450 MHz technology as the ultimate solution. It describes the testbed setup in EDF R&D facilities, the followed methodology to measure the Key

Performance Indicators and assess them. Further, we provide recommendations on the capability of LTE 450 MHz private wireless network to support the MV teleprotection use case.