Summary To eliminate problems of traditional perturb and observe (TPO) maximum power point tracking (MPPT) relying on large scale variable speed wind energy conversion system (VS‐WECS), this paper suggests a variable step size perturb and observe (VS‐PO) MPPT algorithm. The VS‐PO technique is performed to split the power‐speed (P‐ω) curve with four segments every with a particular step size. A large step size is chosen for the two segments distant from the MPP. Otherwise, a smaller step size can be implemented. The proposed algorithm can achieve the maximum power without large oscillations and reduce the settling time under different wind speed conditions, which means high tracking efficiency. Moreover, the model reference adaptive control (MRC) is applied instead of a PI controller to regulate the rotor speed, which maximizes the extracted power. Also, the MRC successful for reducing the large oscillation and settling time compared with the PI controller. The suggested control technique is tested over a 1.5 MW DFIG WECS by MATLAB/Simulink software.

In recent years, the use of active control mechanisms in active suspension systems has attracted considerable attention. The main objective of this research is to develop a mathematical model of an active suspension system that is subjected to excitation from different road profiles and control it using H∞ technique for a quarter car model to improve the ride comfort and road handling. Comparison between passive and active suspension systems is performed using step, sinusoidal and random road profiles. The performance of the H∞ controller is compared with the passive suspension system. It is found that the car body acceleration, suspension deflection and tyre deflection using active suspension system with H∞ technique is better than the passive suspension system.

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