Hue Power Company (PC Hue) has developed a solution to configure backup settings that enhance the reliability of relay protection systems using digital technology.

According to PC Hue, the initiative aims to improve equipment performance, reduce the number of installed devices, simplify wiring and connections, and strengthen the overall reliability of protection and control systems. To achieve this, the company’s engineering team designed a backup configuration solution specifically for digital relay protection systems.

As of the end of February 2025, PC Hue manages and operates 15 unattended 110 kV substations supplying electricity to Hue City. All substations are equipped with protection relays, SCADA automation systems, fire and smoke detection systems, and surveillance cameras. Of these, 14 follow the conventional substation model, while one has been built as a fully digital substation.

To implement the solution, the team collected all measurement and protection signals from voltage transformers (VTs) and current transformers (CTs) at feeder bays and configured backup functions directly on the protection and control devices.

Specifically, to increase the reliability of measurement signals provided by merging units (MUs) for critical protection functions, the relays were configured in accordance with the IEC 61850-9-2 standard. This allows backup measurement signals to be established through a source-selection mechanism, enabling protection devices to receive data from alternative MUs. A logical structure for the backup current circuit of feeder 171 was created using configuration software.

Based on equipment status signals such as health checks and synchronization checks, intelligent electronic devices (IEDs) can automatically select the appropriate input signal source for measurement processing. They also issue alerts related to signal monitoring events.

With this approach, input data for key measurement and protection systems remain continuous, thereby improving system reliability and performance.

The team also implemented a cross-backup scheme for the relay protection system using Process Plus technology. The Process Bus–based backup design allows protection functions to be duplicated across physically separate devices, enhancing redundancy and operational safety.

The solution has been researched and deployed since May 2023 at the unattended 110 kV Phu Bai digital substation.

Through this project, the team has successfully mastered the technology required to configure backup systems and enhance the reliability of digital relay protection. The Process Bus–based backup design maximizes equipment capabilities, reduces the number of installed devices, simplifies wiring, and improves the reliability of protection and control operations.

At the same time, it provides greater flexibility in designing protection and control schemes for unattended digital substations, improves measurement and protection signals, and simplifies management and operational tasks for 110 kV unmanned substations.