Addy Wahyudie

Self-tunable fuzzy logic controller for the optimization of heaving wave energy converters

This paper proposes a new suboptimal reactive control technique for controlling single body heaving wave energy converter (WEC). A self-tunable fuzzy logic controller is implemented to maximize the absorbed energy while respecting the physical limitations of the device. Particle swarm optimization (PSO) algorithm is utilized to carry out an on-line optimization process of the fuzzy membership functions (MFs) embedded in the fuzzy controller. The proposed PSO-FLC out-performed the conventional fuzzy logic controller (C-FLC) in terms of improving reference signal tracking accuracy, widening the device wave absorption bandwidth, and preserving a degree of robustness to model uncertainties.

A binary variant of lightning search algorithm: BLSA

Lightning search algorithm (LSA) is a novel nature-inspired optimization algorithm based on the phenomenon of lighting. This optimization algorithm is generalized from the mechanism of step leader propagation. In this study, a variant of LSA for solving binary optimization problems called as binary LSA (BLSA) is presented. It is done by introducing some modification and introducing tangent hyperbolic sigmoid activation function in updating process of the original version of LSA. To evaluate the quality, convergence rate and robustness of the algorithm, the BLSA is tested with a set of well-utilized 24 benchmark functions. Furthermore, a comparative study with other four well-known binary optimization methods is given for validation of the BLSA performance. The results affirm that the proposed BLSA outperforms the other binary optimization algorithms in multidimensional search space in terms of search accuracy and convergence.

Controlling heaving wave energy converter using function-based model predictive control technique

This paper proposes a new reactive control technique for controlling single body heaving wave energy converter (WEC). A function-based continuous model predictive controller (MPC) is implemented to maximize the absorbed energy while respecting the physical limitations of the device. Laguerre orthonormal functions are deployed to approximate the input variable trajectory, which reduces the computational burden associated with MPC. The developed control strategy is evaluated using both monochromatic and polychromatic sea states. The function-based mode predictive controller showed decent reference signal tracking capabilities, optimizing the control effort to achieve maximum power transfer, while respecting the actuators mechanical and electrical limitations. Also the controller provides means to alleviate the problem of excessive real/reactive power flows.

Fuzzy logic based reactive controller for heaving wave energy converters

This paper presents a new control strategy based on fuzzy logic for maximizing the absorbed energy of heaving wave energy converters (WEC). The fuzzy logic controller is responsible of minimizing the discrepancy between the optimal reference buoy velocity and the actual buoy velocity, hence maximizing the captured power for irregular sea environment. The proposed controller performed well compared to a conventional fixed reactive control strategy.

Sliding mode control for heaving wave energy converter

This paper considers sliding mode controller (SMC) for heaving wave energy converter (WEC). The proposed SMC is implemented to maximize the absorbed energy of the heaving WEC. The problem of chattering control force is solved via the approximation method using the saturation function. The proposed method is tested using polychromatic sea state to simulate the real sea environment. A large difference in energy absorption is resulted using the proposed method compare to a freely motion of heaving WEC. The proposed method maintains the excursion of the buoy within the acceptable limit. The proposed method can maintain the maximum energy absorption despite the presence of uncertainty in its model parameter.

Sliding mode and fuzzy logic control for heaving wave energy converter

This paper proposes two control strategies for controlling the heaving wave energy converter (WEC): sliding mode control (SMC) and fuzzy logic control (FLC). The two methods are implemented to maximize the absorbed energy of the heaving WEC. This can be achieved by designing the control laws so that the buoys velocity follows its reference. The two control strategies are tested using actual polychromatic ocean wave. The control strategies consider the physical limitation of the control force and the buoys elevation. Finally, the performances of the two control methods are tested and compared in the nominal and perturbation scenarios.

Online Damping Strategy for Controlling Heaving Wave Energy Converters Using Three-Phase Bridge Boost Rectifier

One of the main research questions in the field of wave energy technologies concerns the development of an efficient control strategy that can enhance the economic competitiveness of these technologies. Numerous control strategies have been proposed in the past three decades of which only a few are deemed practical. This paper proposes a novel online damping control strategy that is based on the development of an explicit relation for controlling the damping force of a permanent magnet linear generator (PMLG) in real time. The strategy controls the duty cycle of a single-switch three-phase boost rectifier connected at the output terminals of the PMLG. Simulations were conducted to assess the performance of the wave energy converter after applying the proposed strategy under different operating conditions. The results showed satisfactory performances for different sea-state and electrical-loading conditions.

Function-Based Model Predictive Control Approach for Maximum Power Capture of Heaving Wave Energy Converters

This paper investigates the application of function based model predictive control (MPC) approach to control the movement of single-body heaving wave energy converter (WEC). The proposed controller is designed based on the principle of maximum power transfer, at which maximum power absorption is attained. In addition, the suggested MPC controller respects the physical and thermal limitations of the WEC. Also, the generalized architecture of the proposed controller allows for longer prediction horizons and permits to effectively tune the controller based on the surrounding wave environment. Simulations have been carried out to assess the performance of the proposed controller using realistic sea states. Results show that the proposed MPC controller has achieved satisfactory performance allowing the WEC to optimize energy absorption while respecting the system limitations.

Low Cost Controller for Wave Energy Converter

This study addresses a low computation cost controller for maximizing energy absorption of a point absorber in wave energy converters (WEC). The objective can be achieved by ensuring the perfect tracking between the buoy’s velocity and its reference. In particular, the sliding mode control (SMC) is proposed for achieving the maximum energy in WEC. The SMC is considered to be a low cost controller because it is a fixed controller and tuned offline. In order to prove the effectiveness of the SMC, a computer simulation is conducted using the actual polychromatic ocean wave. The proposed controller is tested under the nominal case and its perturbations. The perturbation scenario considers the un-model dynamic of the losses force and perturbation in the excitation force. For the sake of comparison, another low cost controller so called passive reactive controller is simulated under the same condition with the proposed SMC.

Simple Resonance Circuit to Improve Electrical Power Conversion in a Two-Sided Planar Permanent Magnet Linear Generator for Wave Energy Converters

Developing simple, economic, and efficient electrical power conversion systems for wave energy converters (WECs) is an on-going research topic. This paper considers a simple resonance circuit to maximise the ac–dc power conversion of a permanent magnet linear generator (PMLG). To implement this circuit, the PMLG model parameters were obtained. In this paper, we developed a procedure for designing a two-sided planar PMLG considering the corresponding physical parameters. For this method, we set the basic parameters and calculated the derived parameters for the PMLG. The resonance circuit was composed of a three-phase rectifier with a shunt connection of capacitors between its diodes. The value of the capacitors was calculated using the resonance principle at a specific dominant frequency obtained from the location of the WEC installation. We compared the performance of the proposed resonance circuit with that of an existing resonance circuit. The proposed circuit generates more power, requires fewer components, and presents fewer harmonics. In addition, a higher-quality damping force was obtained when using the PMLG connected to the proposed resonance circuit and a resistive load.