vPAC: A Transition to the Future of Substation Automation
Virtual protection, automation, and control (vPAC) – essentially relays as software objects in substation servers – might seem futuristic, but to think it will not catch on in our lifetimes is to deny reality.
Granted, its adoption at scale will take time, but as a concept it is already being trialed in a few small industrial implementations.
We’ve already seen the acceptance of microprocessor-based relays (MBRs) that first appeared in the 1980s. Computing power has come a long way since then, laying the foundation for fully virtual relays today that keep the algorithms and computational intelligence just not the physical device components.
The reality is, vPAC has arrived and the technologies it requires are already among us.
Those who are familiar with IEC 61850 and digital substations can see how close vPAC is; others might guess there is a long way to go. Fortunately, communities and working groups (vPAC Alliance, IEEE, CIGRE, and others) have formed that study virtual substation technologies and produce papers, presentations, tutorials, and guides that are helpful sources of information on this subject.
As concepts, replacing copper-wired protection & control (P&C) with purely ethernet-based systems, then eliminating physical relays altogether, requires a lot of understanding. At this moment in time, there is more thought about the operational technology (OT) and cybersecurity concerns than the benefit that this new technology paradigm could bring to a company.
Regardless, relay virtualization is still advancing, and even in different formats. Another concept, centralized protection and control (CPC), consolidates the tasks of multiple MPRs in a single physical device whereas vPAC functions are executed in a software environment.
To be at the forefront of these P&C technology advancements, Doble Engineering started collaborating with some well-known companies including ABB and Dell Technologies, two market leaders that develop solutions for power grid and information technology (IT) applications worldwide. The beauty of such collaboration is the role and experience that each one plays in the system: all learning from each other.
This collaboration has led to presentations at DistribuTECH 2025 and the 78th Annual Conference for Protective Relay Engineers organized by Texas A&M University. Both presentations showcased a live vPAC demonstration kit that utilized a relay test set from Doble, a virtual relay from ABB, and a server from Dell.
The day prior to the Texas A&M-sponsored event, a pre-conference vPAC tutorial was held. Doble offered an overview of the IEC 61850 standard, ABB presented relay and virtual protection concepts, and Dell explained virtualization from the server perspective.
In Doble’s portion of the tutorial, multiple conventional and digital testing scenarios were handled using a single robust test set: an economical and efficient advantage that is offered to greatly help the transition from analog to digital testing.
So far, audience acceptance of vPAC technology has been positive. Questions related to protection redundancy have been the most common. This concern is natural and has been since the beginning of the protection era and it will continue no matter the technology that is used.
Three takeaways for further exploration:
- When compared to testing an analog relay, testing a virtual relay is not as hard as it might seem. Essentially, the relay tester is only changing the medium of test lead connections from a bunch of copper cables to fiber optic or Ethernet cables. Doble Engineering is working hard to make the analog-digital-virtual transition as seamless and easy as possible.
- Redundancy can be in any part of the system, but redundancy of communication channels is key since they are the backbone of virtual protection technology.
- Companies exist that not only offer solutions for vPAC, CPC, and IEC 61850 standard-based protection applications, but also have the knowledge and technical expertise to support implementing them. Doble Engineering is one of those companies.
Written By: Marcos Velazquez, Jun Verzosa, Joseph Stevenson, and Jose Ruiz
Additional Information:
- The Digital Shift: Navigating the Transition from Analog to Digital
- Looking at IEC 61850, Part 5: The Investment
- Learn about Doble Protection Testing Solutions
