Virtualization of Protection Systems in Distribution Substations: Design, Implementation, and Performance Testing

Over the past century, protection systems have evolved from electromechanical relays performing individual protection functions to microprocessor-based intelligent electronic devices (IEDs) that integrate protection, automation, and communication functionalities for multiple assets. Each technological transition has required extensive training and a complex industry-wide acceptance process. The next logical evolution step in protection systems is virtualization, where relay instances for an entire substation can be hosted on a computer server with real time processing environment. The Process Bus technology bridges the last gap between process-level and protection algorithms in a virtual environment by providing measurement data in digital form. This paper explores the application of virtual protection relay (VPR) technology for distribution substation in lab environment. The proposed VPR system layout includes two 66kV lines, two transformer banks (22.4 and 28 MVA each), two 12kV distribution circuits, capacitors for both voltage classes, and busbar protection. Sampled measured values (compliant with IEC 61850-9-2LE) are provided by merging units from two different vendors, showcasing interoperability. Two VPR servers operate in parallel to ensure redundancy. Analog values are applied to the MU as voltage and current inputs. Process values can be generated from real time digital simulator (RTDS). In addition to discussing the virtual protection system's architecture and design considerations, authors present test results from various fault scenarios, including operating times. The testing plan also covers network stress tests and loss of GPS time synchronization to assess system performance under abnormal conditions. Authors discuss benefits of virtualization and lessons learned during the system testing.