ADRC is a modern, robust control strategy designed to handle system uncertainties and external disturbances without relying on an accurate mathematical model. It works by lumping all unknown dynamics and external effects into a “total disturbance,” which is continuously estimated in real time using an Extended State Observer (ESO). This disturbance estimate is then actively compensated through a simple state-feedback law, allowing the controller to maintain stability and performance even under harsh or unpredictable conditions. As a result, ADRC delivers strong disturbance rejection, fast dynamic response, and high reliability, making it an attractive solution for robotics, automation, power systems, and other real-world applications where precision and robustness are essential.

With increasing demand for energy due to limited conventional sources and population growth has led to the restructuring of the current electricity grid to incorporate renewable energy sources (RES). However, RES irregularities pose significant technical barriers for stable and reliable power system operation. These irregularities cause deviation in the system frequency. To maintain system frequency at a pre-specified value, a load frequency controller is required. Also, with the advancement of information technology and by incorporating intelligent electronic devices (IEDs), communication networks, and sensory networks, the current power system has evolved into a cyber-physical power system (CPPS). This transformation into CPPS increases the efficiency and makes the power system more intelligent. But the power system becomes more prone to cyber attacks, and thus, the security of the power system is compromised.

VIC plays an important role in ensuring the stability and reliability of MGs, particularly in frequency control. As the energy sector moves towards decentralised systems such as MGs, maintaining grid frequency at a constant level becomes difficult due to the intermittent nature of RESs and dynamic load demand. In this context, VIC is considered a solution for mitigating variations in frequency that may be threaten grid reliability. The key issue faced by MGs with significant RES penetration is lack of inbuilt inertia; thus, maintaining frequency stability is a key challenge. VIC mimics the behaviour of a synchronous generator by dynamically adjusting the output of inverters in response to changes in frequency.