Development of a Hydraulic Brake Control System for 100kW Horizontal Axis Wind Turbines using Pressure Relief and Directional Valves

摘要

In order to satisfy specification required by standard a hydraulic brake control system is developed to be implemented to a 100 kW horizontal axis wind turbine under construction. The hydraulic brake control system consists of mechanical brake, hydraulic system and controller. The brake controller has two control modes i.e. normal braking and emergency braking. The hydraulic brake was designed to be able to stop the wind turbine from critical condition i.e. wind speed 21 (m/s) and turbine rotor speed 45 rpm without any help of other means. From calculation it was obtained that torque at the brake be 1.49 kNm. The brake has brake disc whose diameter is 61 cm. The hydraulic system is constructed by a hydraulic pump, a relief valve, a directional valve and three calipers fitted with pads each having area of 37.2 cm~2. A brake controller sends on/off signal to activate/deactivate pump and directional valve. From the experimental results using test bed in the laboratory it is concluded that when initial rotational speed is 600 rpm the mechanical brake could stop the rotating mass in 1.2 second under hydraulic pressure setting 18 bar and 1 second under pressure setting 30 bar. From numerical analysis result it is estimated that when the hydraulic brake is installed in the real wind turbine it can stop the turbine from the critical condition in 1,1 second using hydraulic pressure setting 18 bar with deceleration of 283.8 rpm/sec just before stopping.