MSOA-optimized FOFPID controller for frequency stability of distributed power system under the influence of cyber-attacks

Abstract

A distributed power system operating independently, with low inertia, high distributed energy resources penetration, intermittency from solar and wind causes sudden power imbalances. Also the open network communication channels in the isolated hybrid power system make the system more vulnerable to disturbances and cyber-attacks. The fluctuation in frequency due to load change or cyber-attack in distributed energy system and the load frequency control (LFC) signal affects all other energy sources and performance of the system gets affected. Cyber-security attacks encompass denial of service (DOS) attacks which cause signal unavailability. In data integrity attacks (DIA), signals are altered with noise, posing a significant threat to the stability of the entire network. This paper aims to investigate the challenges of cyber-security associated with distributed generation systems and thereby presenting an effective control method to mitigate the impact of cyber-attacks. The control strategy involves a robust fractional order fuzzy proportional integral derivative (FOFPID) controller integrated with advanced optimization technique i.e., Modified Snake Optimization Algorithm (MSOA) to protect the renewable integrated isolated hybrid power system. The distributed power generation system with DOS and DIA are modeled and analyzed to realize the repercussions of system instability and performance degradation. Controllers like PID, fuzzy PID, and FOFPID tuned with MSOA are demonstrated in this work. The suggested approach is validated through simulations of a distributed generation system under various case studies. The DOS is first applied with photovoltaic (PV), wind, and both PV-wind signals and then DIA is introduced in the LFC signal. The study further incorporates stability analysis, impact of delays in renewable generation on system stability, and sensitivity analysis. The results clearly demonstrate the superior performance of the presented controller over PID and FPID controllers. The recommended controller effectively maintains the system stability and minimizes the degradation in the performance and ensures secure operation during and after the severe cyber-attacks.