Yongjun Dong

Development of a simple power controller for horizontal-axis standalone tidal current energy generation system

Tidal current energy, which is one of the most predictable forms of ocean renewable energy, is mainly utilised for electricity generation. This paper presents a simple control strategy for an optimal extraction of output power from a horizontal-axis variable speed tidal current turbine generation system with a permanent magnet synchronous generator (PMSG) that is driven directly by a fixed-pitch turbine. The maximum power point tracker (MPPT) extracts the turbines maximum power from cut-in current velocity to rated value by measuring only dc link parameters. Together with a dc-dc converter PWM controller, MPPT variable-step searching algorithm is modelled and simulated using Matlab/Simulink software. The simulation results indicate that the variable-step searching algorithm can effectively track the maximum power point without collecting the data of tidal current velocity or rotor speed. Such MPPT controller provides a simple and practical method for the maximum power control of standalone tidal current energy conversion system.

Development and Application of a Simple and Reliable Power Regulator for Small-scale Island Wind Turbine

Abstract Wind power generation is one of the most effective ways to solve the electric power supply in islands. This paper presents a simple, reliable, and effective power regulating device for small-scale island wind turbine, especially for the turbines protection during strong winds. The regulator consists of a rigid tail with an electrical control rotating an aerodynamic vane to yaw the rotor edgewise to the wind direction during high wind speeds, an electric linear actuator, and a controller. Compared with the conventional mechanical vane applied in small-scale wind turbines, such a device possesses several advantages of simple structure, high controllability, and increased reliability. The implementation of rotating the vane actively only depends on the generator speed by measuring AC electrical frequency and the output power by measuring two DC electrical quantities, and no mechanical sensors are needed. The regulator has been applied to a 15-kW prototype operating on an island for more than three years. Field test results indicate that the regulator can effectively turn the rotor out of the wind direction and its behavior agrees well with simulations. Such means of power regulating for small-scale wind turbines can be advantageously utilized compared to other mechanical or electromechanical methods.

Development and Performance Analysis of a Small Island Wind Turbine Generator System with High Reliability

A small wind turbine generator system applied in coastal areas and islands must have good structures and protective actions to ensure reliable operation. In this paper, a small wind turbine prototype with high reliability is designed and examined in the real island conditions. With respect to lightning resistance, the whole structure has good lightning discharge channels, especially for the protection of the blades. Extensive use of nonmetallic materials on the critical components dramatically improves the turbine’s corrosion resistance and ensures the mechanical strength of the structures. For overspeed protection and power regulation, a furling device based on electric-driven control technology is designed and applied. After operation of the prototype for a year and a half, the results indicate that the performance of the turbine is very stable, and the electric-driven method of furling is very effective for protecting the turbine in strong winds. These measures are effective for improving the turbines’ reliability and are helpful for the application of small wind turbines in the marine environments.