Abstract
The growing integration of renewable energy in both islanded and interconnected microgrids has rendered Cyber-physical stability and resilience a vital area of research. Conventional controllers, including PID and linear state-feedback, are susceptible to network-induced delays, denial-of-service (DoS) attacks, and false data injection, resulting in diminished reactive power support and the risk of voltage collapse. This paper proposes an Observer-Aided Robust Control Framework that integrates an Event-Triggered Sliding Mode Controller (ET-SMC) with improved anomaly detection to address these challenges. An Extended Kalman Filter (EKF) and Sliding Mode Observer (SMO) are formulated to estimate hidden state variables and identify malicious data alterations with high sensitivity, facilitating dependable control decisions in the presence of Cyber-attacks. The performance of anti-windup PID and baseline SMC is evaluated against ET-SMC with observer augmentation, demonstrating that the proposed strategy offers enhanced robustness, quicker transient response, and diminished chattering. A stability-guaranteed Event-triggered communication protocol is developed through Lyapunov analysis to reduce bandwidth consumption while maintaining voltage and reactive power regulation. The proposed framework is validated on a real-time OPAL-RT hardware-in-the-loop (HIL) microgrid testbed, demonstrating its effectiveness in scenarios involving renewable intermittency, communication noise, and coordinated Cyber-attacks. Comparative results demonstrate that ROC-based detection performance and time-domain simulations underscore the advantages of observer-aided ET-SMC in ensuring resilient, low-bandwidth, and real-time Cyber-physical control for next-generation power grids.
Data availability
The datasets generated and/or analyzed during the current study are not publicly available due to some restriction but are available from the corresponding author on reasonable request.
Abbreviations
- (A, B, C):
-
Continuous-time system matrices (state, input, output)
- \(\alpha,\beta\) :
-
Positive design scalars
- CPS:
-
Cyber-physical systems
- CPPS:
-
Critical cyber-physical systems
- (d(t)):
-
Unknown disturbance or attack signal
- \(\hat{d}\) :
-
Reconstructed disturbance estimate
- \(\delta\) :
-
Bounded disturbance level
- DG:
-
Distributed generation
- DDoS:
-
Distributed denial-of-service attack
- DoS:
-
Denial-of-service attack
- DRAs:
-
Data replay attacks
- EKF:
-
Extended Kalman filter
- ETSMC:
-
Event-triggered sliding mode control
- FACTS:
-
Flexible AC transmission system
- FDI:
-
False data injection
- FDIA:
-
False data injection attack
- FPGA:
-
Field-Programmable gate array
- (F):
-
Set of faulty or attacked communication channels
- HIL:
-
Hardware-in-the-loop
- HMIs:
-
Human–machine interfaces
- ICS:
-
Industrial control systems
- \({I}_{d},{I}_{q}\) :
-
d–q axis currents
- IG:
-
Induction generator
- ISE:
-
Integral squared error
- (J):
-
Lyapunov function or cost function
- (K):
-
EKF Kalman gain
- \({K}_{s}\) :
-
Sliding mode control gain (discontinuous component)
- (L, R):
-
Inductance and resistance
- \({L}_{SMO}\) :
-
Sliding mode observer (SMO) injection/gain matrix
- \({\lambda}_{min}\) :
-
Minimum eigenvalue of a matrix
- (P):
-
EKF error-covariance matrix
- (P, Q):
-
EKF process and measurement covariance matrices
- RES:
-
Renewable energy system
- \({\Gamma}\) :
-
Event-trigger threshold parameter
- \(\Delta = y\left( {t_{k} - y\left( t \right)} \right)\) :
-
Triggering error
- \(\hat{x}\) :
-
State estimate (observer/EKF/SMO)
- \(\tilde{x} = x - \hat{x}\) :
-
State estimation error
- (x):
-
System state vector
- (y):
-
Measurement/output vector
- (u):
-
Control input vector
- \({u}_{eq}\) :
-
Equivalent (continuous) control component of SMC
- \(\omega\) :
-
Grid angular frequency
- \(\sigma\) :
-
Sliding variable(often = s\(\left(x,t\right))\)
- (s(x,t)):
-
Sliding surface function
- SG:
-
Synchronous generator
- SMC:
-
Sliding mode control
- SMO:
-
Sliding mode observer
- STATCOM:
-
Static synchronous compensator
- SVC:
-
Static VAR compensator
- \({T}_{s}\) :
-
Minimum inter-event time (to prevent Zeno behavior)
- TSA:
-
Time synchronization attack
- \({t}_{k}\) :
-
k-th triggering instant
- SCADA:
-
Supervisory control and data acquisition
- \({u}_{sw}\) :
-
Switching (discontinuous) control part
- \(\left\| * \right\|\) :
-
Euclidean or induced matrix norm
- USB:
-
Universal serial bus
- \({V}_{d},{V}_{q}\) :
-
d–q axis voltages
- \(\eta\) :
-
Boundary layer or saturation thickness
- (0):
-
Zero vector or zero matrix
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Acknowledgements
This work was supported by Universiti Tenaga Nasional (UNITEN) through BOLD Refresh Publication Fund (J510050002-IC-6 BOLDREFRESH2025-Centre of Excellence) for providing all out-laboratory support. The authors also express their appreciation to the Deanship of research and graduate studies at King Khalid university, Saudi Arabia for funding this work through large research project under Grant no: RGP 2/327/46.
Funding
This work was supported by Universiti Tenaga Nasional (UNITEN) through BOLD Refresh Publication Fund (J510050002-IC-6 BOLDREFRESH2025-Centre of Excellence) for providing all out-laboratory support.
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AM; AR: Research Concept & Design, AS; SM: Interpretation of data, RKR; JKB: Manuscript preparation, HH; PM: Design and Analysis, AM; HLA: Reviewing and Editing. All authors reviewed the manuscript. All authors were involved in editing the final manuscript. The author(s) read and approved the final manuscript.
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Mohanty, A., Ramasamy, A., satpathy, A. et al. Observer aided robust control for cyber physical power grids with event triggered sliding mode controller. Sci Rep (2026). https://doi.org/10.1038/s41598-026-44084-5
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DOI: https://doi.org/10.1038/s41598-026-44084-5
