Design and Performance Assessment of a Virtualized IED for Digital Substations

TL;DR

This work addresses the high cost and upgradeability challenges of IEC 61850-based digital substations by developing a server-based virtual IED (vIED) that emulates hardware IED protection functions. The architecture comprises modular software components for control, IEC 61850 communication, data processing, and protection logic, with key methods including a SOGI-based $40$–$70$ Hz frequency-tracking scheme and a nonlinear Kalman filter for phasor estimation. It evaluates performance across $48$ fault scenarios (each repeated $50$ times), reporting a global mean response time of $5.5278$ ms with a standard deviation of $1.1332$ ms, and demonstrates acceptable timing for time-sensitive protection in a virtualized setting. The results support the feasibility of vIEDs as scalable, cost-effective alternatives to hardware IEDs in digital substations, while highlighting practical challenges in cybersecurity, redundancy, interoperability, and network robustness that must be addressed for practical deployment.

Abstract

Digital substations have significantly enhanced power grid protection by replacing traditional copper wiring with fiber-optic communication and integrating IEC 61850-compliant Intelligent Electronic Devices (IEDs), resulting in greater efficiency, reliability, and interoperability. While these advancements provide improved interoperability, challenges such as high costs, complex networks, and limited upgradeability persist. To mitigate these issues, the virtualization of IEDs has emerged as a cost-effective solution, offering scalability, simplified maintenance, and reduced hardware costs by replacing traditional hardware-based IEDs with software-based counterparts. However, the performance and reliability of virtual IEDs (vIED) must be rigorously evaluated to ensure their robustness in real-time applications. This paper develops, implements, and evaluates a vIED designed to match the performance of its hardware-based counterparts. The vIED was deployed on a server using virtual machines, with its core logic implemented in low-level programming languages to ensure high-speed, deterministic behavior. The performance was evaluated using real-time simulations, focusing on the response times of the protection functions. The results demonstrated that vIEDs achieved acceptable response times, validating their suitability for deployment in critical time-sensitive environments within digital substations.

Figures (12)

• Figure 1: Transition from multiple standalone to virtualized IEDs.
• Figure 2: Software architecture of the vIED divided into modules.
• Figure 3: Adapted SOGI FLL algorithm for frequency tracking.
• Figure 4: Nonlinear Kalman filtering algorithm used for phasor estimation.
• Figure 5: PIOC operation principle with pickup and trip output signals.