So, it is clear from the results that the proposed directional relaying method based on phase angle difference of fault to prefault positive sequence current has satisfactory performance for different critical system and fault conditions.
Moreover, it has been extensively applied in a variety of applications, for instance, detection of financial fraud, network intrusion, failures in critical systems, sensor faults in sensor networks, speech recognition, and traffic monitoring [23, 32].
Such conditions increase the possibility of system faults, which are characterized by critical and unpredictable changes in system dynamics.
To realize the ability of the proposed scheme under single pole tripping, several critical cases are addressed such as high fault resistance (HFR), different fault locations, different fault types, change in power flow direction, variation in source capacity and other critical system situations are addressed to prove the correct behavior of the proposed procedure.
For some AC system faults, CF occurs when the AC bus voltage drops by more than a critical value, while CF is avoided for other AC system faults which cause the same voltage drop.
Task manager contains critical system processes.
However, even if the software for RH control systems has been developed using best practices, the system might still fail due to undetected faults (bugs), hardware failures, etc. Critical systems therefore need capability to tolerate faults and resume operation after their occurrence.
However, the growing complexity of functions performed by embedded software has increased the number of accidents caused by software faults in critical systems.
Therefore, safety critical systems have to meet maximum fault tolerance and reliability requirements.
The reliable detection of faults located in the control loop of safety critical systems is an important aspect in reducing potential hazards induced by possible faults.
The results also confirm both the difficulty and the benefits of pursuing requirements completeness, especially in terms of fault tolerance, during development of critical systems.
