A Dynamic State Estimation Based Centralized Scheme for Microgrid Protection

The spread of microgrids is one of the most promising recent trends in the field of power systems, as they can help integrate distributed power sources and other cutting-edge technological advancements into power systems. In order to facilitate their expansion, more research on microgrid protection is needed, as they pose serious challenges to or even totally invalidate traditional protection schemes. In this paper, a comprehensive protection scheme for microgrids is proposed. Our scheme is based on an already extensively researched framework based on dynamic state estimation (DSE) and aims to utilize it for microgrid protection. The individual protection zones of a microgrid are monitored by settingless relays which continuously receive measurements and perform DSE in the time domain to detect abnormalities. However, power faults are not the only root cause of abnormal measurements. Relays can also receive erroneous measurements due to hidden failures in the system or due to malicious actors that try to inject false measurements. For this reason, we add a centralized layer to our scheme. This layer receives measurements from all the settingless relays of the microgrid and uses DSE in the quasi-dynamic domain to determine whether a settingless relay detects an abnormality due to a fault or due to a reason that does not warrant tripping action, which allows us to block erroneous tripping actions. Therefore, our layered approach increases the security and dependability of microgrid protection compared to traditional protection schemes.