Applied Research Of Accumulator In Megawatt Wind Turbine Yaw System

As a new type of and non-pollution production of energy, wind driven generatoris increasingly being paid more and more attention. Along with the widespread use ofwind power technology, the wind driven generator is also gradually towardslarge-scale development. Now a large number of enterprises have produced megawattwind driven generator. The yaw system is an important component of the wind drivengenerator, to some extent; it can improve the utilization efficiency of the wind power.The accumulator is an important auxiliary part in the wind turbines drift hydraulicsystem, store energy, act as the emergency power supply and play an important rolefor the normal work of the system.Based on the megawatt wind turbine yaw hydraulic system research as the mainline, the working parameters of accumulator in hydraulic system and the workingperformance of the yaw brake hydraulic system are researched. First of all, on thebasis of consulting a large number of relevant materials, select drift hydraulic system,analyze the system and establish the mathematical model of hydraulic system withsystem modeling method. Designate the type of each element in the system, theworking parameters and geometric parameters, calculate the actual transfer functionof hydraulic system, establish the simulation model of drift hydraulic system in theSimulink system, obtain the Bode diagram and draw a conclusion that it is stable.Secondly, set up mathematic model of the accumulator, analyze the impacts of theprecharge pressure and the pre filled volume of accumulator on its inherentcharacteristic, calculate the working parameters of accumulator and obtain thereasonable value range. Finally, build the simulation model of drift hydraulic systemin the AMESim and simulate the working performance of the system. The resultsshowed as follows: the drift hydraulic system could primely achieve yawing andbraking; the servo valve mouth opening can control the change of damping torque inthe system; the system can satisfy the need of the change of the external torque. Incomparison with simulated analysis, accumulator is indispensable in hydraulicsystem. Establishing the simulation model of drift hydraulic system in the AMESimwhen the accumulator acts as emergency power supply and investigate the model.The simulation results show that the accumulator serving as emergency power supplycan make the system safety arrestment. Researching the effect of accumulatorworking parameters on yaw and braking performance of system through batching,points out that the precharge pressure and the pre filled volume are3MPa and0.6Lwhich make the working performance of system better and according the optimalparameter values design the accumulator. The results of the study provides referencebasis for design and selection of accumulator in megawatt wind turbine hydraulicsystem.