Diagnosis in Cyber-Physical Systems with Fault Protection Assemblies

Ajay Chhokra, Abhishek Dubey, Nagabhushan Mahadevan, Saqib Hasan, Gabor Karsai

Diagnosability, Security and Safety of Hybrid Dynamic and Cyber-Physical Systems 2018

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Why This Matters

Traditional fault diagnosis in power systems focuses on primary failures but ignores how protection equipment misoperations can cascade faults throughout the system. Cyber-physical systems require integrated analysis of both physical faults and autonomous protection device responses. This work is important because it provides practical diagnosis methods that account for protection assemblies, enabling operators to identify critical failure modes and design better protection strategies.

What We Did

This chapter describes diagnosis methods for cyber-physical systems with fault protection assemblies, using Temporal Causal Diagrams to model fault propagation through protection equipment. The approach captures how protection devices autonomously respond to faults, potentially causing secondary effects or cascading failures. The paper demonstrates the technique on power systems showing how misoperation of protection relays can lead to complete system blackout.

Key Results

The Temporal Causal Diagram approach successfully diagnosed cascading failures in the WSCC 9-bus system, identifying how relay misoperations led to progressive system instability and blackout. The reasoning engine generated multi-fault hypotheses that explained observed anomalies and predicted system-level consequences. The method enabled identification of critical protection assemblies that could trigger cascading failures under fault conditions.

Full Abstract

Cite This Paper

@inbook{Chhokra2018,
  author = {Chhokra, Ajay and Dubey, Abhishek and Mahadevan, Nagabhushan and Hasan, Saqib and Karsai, Gabor},
  chapter = {Chapter 8},
  editor = {Sayed-Mouchaweh, Moamar},
  pages = {201--225},
  publisher = {Springer International Publishing},
  title = {Diagnosis in Cyber-Physical Systems with Fault Protection Assemblies},
  year = {2018},
  address = {Cham},
  isbn = {978-3-319-74962-4},
  abstract = {Fault Protection Assemblies are used in cyber-physical systems for automated fault-isolation. These devices alter the mode of the system using locally available information in order to stop fault propagation. For example, in electrical networks relays and breakers isolate faults in order to arrest failure propagation and protect the healthy parts of the system. However, these assemblies themselves can have faults, which may inadvertently induce secondary failures. Often these secondary failures lead to cascade effects, which then lead to total system collapse. This behavior is often seen in electrical transmission systems where failures of relays and breakers may cause overloading and the disconnection of parts of an otherwise healthy system. In the past, we had developed a consistency based diagnosis approach for physical systems based on the temporal failure propagation graph. We now describe an extension that uses the concept of timed discrete event observers in combination with the timed failure propagation graphs to extend the hypothesis to include the possibility of failures in the fault protection units. Using a simulated power system case study, we show that the combined approach is able to diagnose faults in both the plant and the protection devices.},
  booktitle = {Diagnosability, Security and Safety of Hybrid Dynamic and Cyber-Physical Systems},
  contribution = {colab},
  doi = {10.1007/978-3-319-74962-4_8},
  file = {:Chhokra2018-Diagnosis_In_Cyber-Physical_Systems_with_Fault_Protection_Assemblies.pdf:PDF},
  keywords = {fault diagnosis, protection relays, cascading failures, power systems, cyber-physical systems},
  tag = {platform,power},
  url = {https://doi.org/10.1007/978-3-319-74962-4_8}
}
Quick Info
Year 2018
DOI 10.1007/978-3-319-74962-4_8
Keywords
fault diagnosis protection relays cascading failures power systems cyber-physical systems
Research Areas
CPS emergency
Search Tags

Diagnosis, Cyber, Physical, Systems, Fault, Protection, Assemblies, fault diagnosis, protection relays, cascading failures, power systems, cyber-physical systems, CPS, emergency, 2018, Chhokra, Dubey, Mahadevan, Hasan, Karsai