Multi-objective design optimization of a large-scale directdrive permanent magnet generator for wind energy conversion systems

This paper presents a simukaneous multi- objective optimization of a direct-drive permanent magnet synchronous generator and a three-blade horizontal-axis wind turbine for a large scale wind energy conversion system. Analytical models of the generator and the turbine are used along with the cost model for optimization. Three important characteristics of the system i.e.,the total cost of the generator and blades, the annual energy output and the total mass of generator and blades are chosen as objective functions for a multi-objective optimization. Genetic algorithm （GA） is then employed to optimize the value of eight design parameters including seven generator parameters and a turbine parameter resulting in a set of Pareto optimal solutions. Four optimal solutions are then selected by applying some practical restrictions on the Pareto front. One of these optimal designs is chosen for finite element verification. A circuit-fed coupled time stepping finite element method is then performed to evaluate the no-load and the full load performance analysis of the system including the generator, a rectifier and a resistive load. The results obtained by the finite element analysis （FEA） verify the accuracy of the analytical model and the proposed method.

变速风电系统形成强迫功率振荡扰动源分析

结合风力机运行特性,探讨永磁直驱变速风电系统成为强迫振荡源的原因。首先理论分析由风剪切和塔影效应引起的风力机机械转矩波动特性,推导出风电系统电磁转矩波动与机械转矩波动的关系表达式,采用频域法分析风电机组的输出功率特性,并通过时域仿真进行验证。研究结果表明,永磁直驱风电系统可能成为共振型低频振荡的扰动源,其功率波动频率与风力机转速相关,幅值与风力机运行点、风电系统参数和系统阻尼相关。引起共振的主要因素是塔影效应,而风剪切分量很难引发共振。