Integrated Centralized Substation Protection

Meliopoulos, A P
Cokkinides, George
Albinali, Hussain
Myrda, Paul
Farantatos, Evangelos
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Substation cyber assets are mission critical for protection and control of substations. Managing and ensuring their secure operation is of paramount importance. A known vulnerability is hidden failures which are responsible for about 10% of mis-operations and their detrimental effects on system reliability. The paper presents an integrated centralized substation protection approach that is based on the recently developed setting-less relays which are integrated into a centralized substation protection scheme with the following features: (a) fast, dependable and secure protection of each substation protection zone by a settingless relay, (b) supervision of each settingless relay by validating relay input data by a substation wide state estimator, (c) self-healing against hidden failures by detecting and identifying compromised data and replacing them with estimated values, thus ensuring that the settingless relays will always operate on validated data. The paper provides a summary review of the settingless protective relay and introduces the Integrated Centralized Substation Protection Scheme (ICSP) which uses the data from all settingless relays in the substation to perform a substation wide state estimation. The state estimator uses a hypothesis testing algorithm to determine whether (a) data are valid with no faults or hidden failures, (b) data are valid and a fault exists in the system, or (c) some data are invalid due to hidden failures. In the last case, the state estimator uses the substation state and model to replace the compromised data with estimated values and thus enabling self-immunization against hidden failures. A byproduct of the method is the substation state estimate which is transmitted to the control center where it is used with the state from all substations to synthesize the system wide state estimate and model. Architectural issues are addressed as well as migration issues of existing systems into the proposed ICSP.
Monitoring, Control, and Protection, setting-less relay, centralized substation protection, dynamic state estimation, hidden failures
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