Abstract
Cyber-Physical Energy Systems (CPESs) are energy systems which rely on cyber components for energy production, transmission and distribution control, and other functions. With the penetration of Renewable Energy Sources (RESs), CPESs are required to provide flexible operation (e.g., load-following, frequency regulation) to respond to any sudden imbalance of the power grid, due to the variability in power generation by RESs. This raises concerns on the reliability of CPESs traditionally used as base-load facilities, such as Nuclear Power Plants (NPPs), which were not designed for flexible operation, and more so, since traditionally only hardware components aging and stochastic failures have been considered for the reliability assessment, whereas the contribution of the degradation and aging of the cyber components of CPSs has been neglected. In this paper, we propose a multi-state model that integrates the hardware components stochastic failures with the aging of cyber components, and quantify the unreliability of CPES in load-following operations under normal/emergency conditions. To show the application of the reliability assessment model, we consider the case of the Control Rod System (CRS) of a NPP typically used for a base-load energy supply.
Highlights
Published: 1 June 2021Cyber-Physical Systems (CPSs) are systems that integrate cyber components within hardware systems in which physical processes take place [1]: when the processes relate to energy production, transmission and distribution, they are called Cyber-Physical EnergySystems (CPESs) [2]
Given the stable steady-state energy supply demanded to the base-load Cyber-Physical Energy Systems (CPESs), manoeuvring capabilities were designed for seldom operations, mainly triggered by safety needs [4] and with limited safety margins or capabilities to satisfy flexible operation during frequent and fast-changing demand scenarios
To assess the reliability of CPESs accounting for the aging and degradation of cyber systems, in [15] we proposed a multi-state model for describing the aging process driven by memory leakage [16,17], which leads to service rate decrease and, eventually, data-jamming in the mission queue [18,19], which, in turn, increases the memory request; in such conditions, the cyber system blocks its function, significantly increasing the control delay [20,21], deteriorating the system stability and controllability during transients, when the amount of memory available cannot satisfy the demand of the mission queue
Summary
Cyber-Physical Systems (CPSs) are systems that integrate cyber components within hardware systems in which physical processes take place [1]: when the processes relate to energy production, transmission and distribution, they are called Cyber-Physical Energy. Since the base-load CPESs are normally expected to operate under stable steady-state conditions, for which any change of the cyber part setting can be detected and corrected without losing control of the system [5,6,7], aging of cyber parts is not a concern, whereas under frequent, fast-changing transients, as Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations It is in the case of load-following CPESs here considered, aging of the cyber part cannot be neglected [8]. The remainder of paper is as follows: Section 2 presents the NPP case study considering both hardware components’ stochastic failures and the aging of cyber components in load-following operation scenarios; Section 3 presents relative modelling works of cyber aging and the proposed multi-state model accounting for the cyber aging process; the reliability assessment procedure, embedding the multi-state model of Section 3, is presented in Section 4; the results of the application of the reliability assessment of Section 4 to the case study of Section 2 are reported and discussed in Section 5; and in Section 6, conclusions are drawn
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
