CYBER-ATTACK DETECTION AND MITIGATION IN LOAD FREQUENCY CONTROL OF RENEWABLE ENERGY SOURCE INTEGRATED MICROGRID

Abstract

Power systems have great importance to socio-economic development due to the fact that the entireworld relies on the electric network power supply for day-to-day life. To address the increasing demand for reliable power supply and tackle environmental challenges, integration of renewable energy sources (RESs) into power systems is essential and microgrids are established as a practical fix for the RES-induced challenges occurring in traditional power systems. However, due to the increased dependence on communication infrastructure microgrids are highly vulnerable to cyber-attacks, such as denial of service (DoS) and deception attacks, compared to the traditional power system. Hence, for the stable operation of microgrids, it is essential to include attack resilient control measures. Similar to the conventional power systems, the stability and frequency performance of RES-integrated microgrids are also maintained with the help of load frequency control (LFC) system and it is one of the most time-consuming control loops that are vulnerable to cyber-attacks and applies low bandwidth communication infrastructure. The performance degradation of the microgrid LFC system can adversely affect the microgrid operation. For improving the microgrid frequency regulation capability in the presence of RES integration and random loads, various virtual inertia (VI) or auxiliary control mechanisms are generally employed. Hence, this research proposes linear quadratic Gaussian (LQG)-based and regional pole placement (RPP)-based state feedback auxiliary control schemes to elevate the frequency performance and cyberattack/ cyber-resiliency study is conducted in microgrid LFC system with the proposed auxiliary control schemes. Further, in order to simultaneously achieve cyber-attack resilience and communication efficiency, an observer-based event-triggered (ET) secondary control strategy is developed for the microgrid LFC system with uncompromised auxiliary control loop and when the secondary measurement channel is under energylimited DoS or false data injection (FDI) attack. Additionally, sufficient conditions of stability are derived using Lyapunov–Krasovskii (LK) functional stability analysis considering time-varying communication delay of the secondary measurement channel and the efficacy of proposed work is analyzed through MATLAB/SIMULINK simulation analysis. The proposed VI control techniques could achieve high frequency performance (for instance, ±0.02182 Hz is achieved in the case of LQG-based VI control scheme) and the developed cyber-attack resilient secondary control strategy could attain attack resilience while keeping high communication efficiency (average communication efficiencies of 94.54 % and 96.47 %, respectively, are achieved for DoS and FDI attack resilient control schemes).