Integrating Multivendor Numerical Relays: Substation Design Challenges
July 11, 2024

Mikhail Lukianenko & Richard Adams 

In the realm of modern power systems, the integration of microprocessor-based relays from various vendors can present a considerable challenge for substation designers. These relays, pivotal for ensuring the safety and reliability of electrical networks, often come with proprietary algorithms and logic tailored to specific functionalities. However, when incorporating relays from different manufacturers into a single substation, ensuring seamless interoperability can become a complex endeavor.


The intricate nature of numerical relays lies not only in their diverse functionalities but also in the proprietary nature of their algorithms. Each vendor employs distinct programming methodologies and logic implementations, making it arduous to harmonize their operations within the same substation environment. As a result, engineers face the daunting task of adapting these disparate systems to function cohesively, a process rife with technical hurdles.

One of the primary challenges encountered when integrating numerical relays from different vendors is the need for meticulous coordination of protection schemes. Protective relaying systems are designed to detect and respond to abnormal operating conditions swiftly. However, when relays from multiple vendors are involved, ensuring coordination between protection devices becomes inherently complex. Conflicting trip settings, time delays, and coordination curves must be meticulously aligned to prevent misoperation and ensure system stability.

Furthermore, the adaptation of relay algorithms and logic to work harmoniously poses a significant obstacle. Integrating devices necessitates in-depth understanding and expertise to mitigate potential conflicts and ensure reliable operation. Moreover, debugging and troubleshooting issues arising from algorithmic discrepancies and the many other functions integrated into modern devices demand substantial time and resources, further complicating the integration process.

What about digital substations?

In the context of digital substations leveraging the IEC 61850 standard, the challenges of incorporating numerical relays from different vendors can be more complex. IEC 61850, an international standard defining communication protocols for intelligent electronic devices at electrical substations, aims to enhance interoperability and efficiency within substations. However, despite its standardized framework, interpretation by manufacturers can present obstacles to seamless integration.

One of the key tenets of IEC 61850 is the standardization of communication protocols and data models, facilitating seamless information exchange between devices, although in practice it may not be quite so simple. However, its use is gaining momentum, with initial trials by users now giving way to continued implementation and adoption, recognizing that there are benefits to be had once the processes are understood.

Possible Solutions

Despite the hurdles faced, there are promising developments in interoperability standards and collaborative efforts within the industry. IEC 61850 interoperability testing demonstrates the compatibility of devices from various vendors, streamlining integration processes.

To summarize, while integrating numerical relays from different vendors presents challenges for P&C engineers, especially in the realm of digital substations, there is reason for optimism. Despite the complexities to ensure smooth interoperability within IEC 61850-compliant systems, projects undertaken to date demonstrate success and benefits. Through dedicated efforts towards standardization and collaboration, there are pathways to conquer these challenges and unlock the full potential of modern power systems.

PSC can help

The protection design using multivendor relays within one project is a challenging task. However, considering all the design experience gained since numerical relays came into being, it can be performed, as completed projects demonstrate.

At PSC, we have significant experience dealing with numerical relays for both conventional and digital substations. This accumulated experience enables us to tackle interoperability issues more effectively. We use reliable, time-proven solutions, considering the characteristics of the specified relays. Vendor-specific proprietary software is utilized for relay parameter settings configuration. Our expertise enhances the overall protection performance and reduces the time required for design and commissioning.

Learn more about PSC’s Power Protection Services or contact us to find out how we can help.