This paper presents event triggered nonlinear controllers for oscillating water column (OWC) ocean wave energy plant. The study is based on event triggered backstepping controller (ET-BSC) and event triggered sliding mode controller (ET-SMC) to control the rotational speed of OWC turbine coupled to generator. The designed controllers are capable to avoid the stalling of Wells turbine so as to maximize its output power. The aim of event triggered control is to minimize the control updates thus providing efficient utilization of resources without compromising the OWC performance. In this regard, aperiodic sampling has been applied using event triggering rule derived from Lyapunov stability analysis. In order to validate the proposed controllers, simulation results have been performed using JONSWAP irregular wave model. It is observed that performance of ET-BSC is better than ET-SMC in terms of defined indices, control effort and inter event execution time.

This paper proposes an optimization based maximum power point tracking (MPPT) algorithm for selection of appropriate external rotor resistances of wound rotor induction generator (WRIG). The generator coupled with a Wells turbine is used in oscillating water column (OWC) wave power plants. The Wells turbine suffers with stalling behaviour that reduces the average output power significantly. Hence, the objective is to prevent aerodynamic stalling of the Wells turbine and hence maximizing the output power simultaneously. But inappropriate selection of rotor resistance leads to excessive power loss. Therefore, two approaches have been applied: (i) the rotor resistance values are selected manually by trial and error method or non-optimized approach (ii) a performance index has been derived and minimized using particle swarm optimization technique to obtain the optimized values of rotor resistance. Simulation results have been performed for turbine efficiency, output power and power loss in external rotor resistance. Finally, the proposed control approach is illustrated for two particular cases of regular and irregular waves.

In this paper, a new control strategy is proposed for the load frequency control in interconnected multi-area power systems. An unknown-input-observer based non-linear sliding mode controller is introduced to compensate the effect of unknown load disturbances and parameter uncertainties in the system. The non-linear sliding mode controller stabilizes the system dynamics by utilizing the estimated states and disturbance uncertainties. The closed loop convergence of the observer based controller is verified using Lyapunov stability analysis. The simulation results of the two-area power system show the effectiveness of the proposed controller even in the presence of generator rate constraints.