State estimation-based centralized substation protection scheme
Albinali, Hussain F.
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Power systems are experiencing drastic changes with the introduction of renewable and customer-owned resources. These changes introduce new challenges in the protection, control, and operation of power systems. They are concurrent with utilities’ efforts to boost system reliability. Such efforts are undermined by the vulnerability of protection system to hidden failures. Accordingly, it is necessary to develop new methods that can cope with new characteristics and avoid relay misoperations because of hidden failures. This dissertation introduces a new dynamic state estimation-based centralized protection scheme (DSEBCPS) at the substation level. This system supplements dynamic state estimation-based protection for individual zones known as “settingless relays” to secure their operation against hidden failures. The DSEBCPS communicates with the settingless relays via the station bus and obtains essential information from each protection zone, such as phasor quantities and status of breakers and disconnects. This information is processed by the DSEBCPS to extract the substation topology and states. Specifically, the DSEBCPS performs dynamic state estimations in the quasi-dynamic domain once per cycle to detect any sort of abnormality within the substation. Upon detecting abnormalities, the DSEBCPS performs hypothesis testing to distinguish between faults and hidden failures. The DSEBCPS detects and locates hidden failures within the substation through hypothesis testing. Then, the DSEBCPS streams the estimated measurements that corresponds to the detected bad measurements to the settingless relay to override the compromised measurement. Its capability to detect hidden failures and replace the compromised measurements in real time secure settingless relays from misoperation and ensure high dependability even with the presence of hidden failures. Such capability bridges a critical gap in protection systems. Critical to this work is the ability to manage data and communications between the various devices (i.e., MUs, settingless relays, and DSEBCPS) within the substation and between the substation and the control center. Therefore, this thesis includes the proposed system architecture, which specifies data management, communication protocols, and the hierarchical structure of the system.