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Wind shear and tower shadow produce a periodic pulse reduction in mechanical torque captured from wind energy resulting in wind energy conversion system (WECS) active power oscillations. In this study, an adaptive neuro-fuzzy controller for static VAR compensator, used in power networks integrated with WECS, is presented to address the torque oscillation problem. The proposed controller consists of a radial basis function neural network representing a third-order auto-regressive and moving average system model and performing the prediction, and a main controller with adaptive neuro-fuzzy inference system providing the damping signal. A modified two-area four-machine power network with WECS integration is applied to validate the proposed implementation, compared with conventional lead/lag compensation. Time-domain simulations prove that the proposed controller can provide a damping signal to improve the active power oscillation and system dynamic stability, influenced by torque oscillations under WECSs synchronised operating condition.

The growing demand for renewable energy necessitates efficient power conversion and grid integration solutions. This work proposes an energy management system (EMS) using a trans Z-source quadratic boost converter (TZSQBC) and puffer fish optimized fuzzy neural network (PF-OFNN)-maximum power point tracking (MPPT). The system integrates photovoltaic (PV) and wind system to enhance reliability and mitigate variability issues. The TZSQBC significantly improves voltage boosting efficiency, ensuring seamless grid integration. The PF-OFNN MPPT algorithm optimizes power extraction from PV system under dynamic environmental conditions. A doubly fed induction generator (DFIG) wind system is incorporated to enhance flexibility and stability. Additionally, a bidirectional DC-DC converter with battery storage ensures efficient energy flow management. The proposed system is evaluated through MATLAB simulations under various test cases, including constant and varying environmental conditions, analysing power efficiency, voltage gain, and total harmonic distortion (THD). A hardware prototype further validates system feasibility, demonstrating effective grid synchronization and improved power quality. Comparative analysis with existing topologies highlights reduced component count, improved duty cycle utilization, and lower voltage stress. The results confirm the proposed system’s effectiveness in achieving stable, high-efficiency renewable energy integration with enhanced power management and minimal harmonic distortion.

This work presents a control strategy for integrating an offshore wind farm into the onshore electrical grid using a high-voltage dc transmission system based on modular multilevel converters. The proposed algorithm allows the high-voltage DC system to operate in grid-connected or stand-alone modes, with the second case supplying power to local loads. In either mode, the modular multilevel rectifier works as a grid-forming converter, providing the reference voltage to the collector network. During grid-connected operation, the modular multilevel inverter regulates the DC link voltage while the generating units are controlled to maximize power extracted from the wind turbines. Conversely, in the event of grid disconnection, the onshore modular multilevel converter takes over the regulation of the AC voltage at the point of connection to the grid, ensuring energy supply to local loads. Simultaneously, the generator controller transitions from tracking the maximum power of the wind turbines to regulating the DC link voltage, preventing excessive power injection into the transmission DC link. Additionally, the turbine pitch angle control regulates the speed of the generator. Mathematical models in the synchronous reference frame were developed for each operation mode and used to design the converter’s controllers. A digital model of the wind power plant and a high-voltage dc transmission system was implemented and simulated in the PSCAD/EMTDC program. The system modeled includes two groups of wind turbines, generators, and back-to-back converters, in addition to a DC link with a rectifier and an inverter station, both based on modular multilevel converters with 18 submodules per arm, and a 320 kV/50 km DC cable. Aggregate models were used to represent the two groups of wind turbines, where 30 and 15 smaller units operate in parallel, respectively. The performance of the proposed control strategy and the designed controllers was tested under three distinct scenarios: disconnection of the onshore converter from the AC grid, partial loss of a wind generator set, and reconnection of the onshore converter to the AC grid.

Sea ports are infrastructures with substantial energy demands and often responsible for air pollution and other environmental problems, which may be minimized by using renewable energy, namely electricity harvested from ocean waves. In this regard, a wide variety of concepts to harvest wave energy are available and some shoreline technologies are already in an advanced development phase. The SE@PORTS project aims to assess the suitability and viability of existing wave energy conversion technologies to be integrated in harbor breakwaters, in order to take advantage of their high exposure to ocean waves. This paper describes the experimental study carried out to assess the performance of a hybrid wave energy converter (WEC) integrated in the rubble-mound structure that was proposed for the extension of the North breakwater of the Port of Leixões, Portugal. The hybrid concept combines the overtopping and the oscillating water column principles and was tested on a geometric scale of 1/50. This paper is focused on the assessment of the effects of the hybrid WEC integration on the case-study breakwater, both in terms of its stability and functionality. The 2D physical model included the reproduction of the seabed bathymetry in front of the breakwater and the generation of a wide range of irregular sea states, including extreme wave conditions. The experimental results shown that the integration of the hybrid WEC in the breakwater does not worsens the stability of its toe berm blocks and reduces the magnitude of the overtopping events. The conclusions obtained are therefore favorable to the integration of this type of devices on harbor breakwaters.

The aim of the study is to evaluate the parametric effect of a power take-off (PTO) system on an integration system of an oscillating buoy wave energy device with a pile-restrained floating breakwater. To consider the viscous effect, the study is carried out with three conditions using OpenFOAM, i.e., the linear optimal PTO system, the fixed PTO damping coefficient, and the Coulomb PTO system. The results show that the maximum wave energy capture ratio (CWR) of the device can merely reach 0.35 in the present work, when considering the viscous effect. This result is smaller than that obtained from potential flow. In addition, the linear optimal PTO coefficient under viscous flow should be larger than the theoretical optimal coefficient in terms of the potential flow. A comparison of the Coulomb damping model and the linear damping model also shows that the Coulomb damping model has a good performance in terms of both wave energy capture efficiency and coastal protection. Hence, the effect of the PTO system on such an integration system can be an essential factor to achieve an optimal design.