Emerging technologies in design and testing of protection relays for transmission system connected to inverter based resources

Integrating a high share of electricity from intermittent and non-dispatchable Inverter Based Resources (IBRs) predominantly from renewable energy sources such as wind and solar are essential for meeting the future energy needs while decarbonising the power sector. However, short circuit responses and dynamic characteristics of IBRs connected to transmission grid are decided by the converter control strategy under different operating conditions which are fundamentally different from traditional synchronous generators (SGs). Consequently, the performances of commercially available protection relays used for transmission lines protection are challenged. Therefore, there is an extreme need for in-depth and groundbreaking studies to develop new or modified techniques on design and testing of protection relays to ensure effectiveness, reliability, and security of operation of the protection system used for transmission network. In this paper, the results of the literature review on the impact of IBRs on the performances of transmission line protections are presented and the emerging technologies that target these challenges to provide the required flexibility, adaptability, and dynamic capability of future protection relays under different operating conditions and regulatory requirements are introduced. In addition, the importance of setting regulatory frameworks and standardization of relay testing strategies using modern validation tools such as Hardware-in-the-loop (HiL), Software-in-the-loop (SiL) real time testing and digital twin environment is highlighted.