摘要
直驱式风力永磁同步发电机(Permanent Magnet Synchronous Generator,PMSG)由风力机直接驱动,取消了齿轮箱,具有结构简单、可靠性高等优点,在风力发电领域具有良好的应用前景。然而,PMSG通过全额变频器与电网连接,变频器的存在使系统的谐波含量增加,从而导致PMSG的损耗与发热增加,其分析与计算也变得十分复杂。因此,对PMSG的损耗和发热进行深入分析与计算具有重要意义。本文依托重庆市自然科学基金项目《MW级风力PMSG及其系统的优化设计研究》,以1台1.5MW的直驱式风力PMSG为例,重点研究变频器类型及控制参数对其损耗和温度分布的影响。
首先,从电磁场基本理论出发,建立了PMSG的二维场路耦合时步有限元模型;其次,分析了变频器的特点,介绍了变频器控制参数及其对谐波的影响;第三,分析了PMSG定子铁心、定子绕组和转子永磁体的谐波损耗计算方法,并根据所建立的模型,针对RL负载、不可控整流器负载和PWM整流器负载,分别计算了PMSG的定子谐波铁耗、定子谐波铜耗和转子永磁体损耗,并对比分析了其变化规律;第四,分别建立了PMSG的二维热网络模型和二维温度场有限元模型,并通过计算得到了PMSG定转子的温度分布规律;最后,讨论并总结了变频器类型及控制参数对PMSG损耗和温度分布规律的影响。
结果表明,在额定转速下,对于带不可控整流负载的直驱式风力PMSG来说,定子铜耗最大,转子永磁体损耗次之,定子铁耗最小;而对于带RL负载和PWM整流器负载的直驱式风力PMSG来说,定子铜耗最大,定子铁耗次之,转子永磁体损耗最小。变频器类型及控制参数对PMSG的损耗和发热有明显影响,最高温度均出现在定子上层绕组处。
本文的研究工作对直驱式风力PMSG的设计和控制,具有参考价值。
The permanent magnet synchronous generator(PMSG) is directly driven by the wind turbine, the gearbox is not needed, and it has the advantages such as simple structure, high reliability, and so on. It has wide application in the area of wind generation. However, PMSG is connected with the grid through the full scale converter. The converter produces more harmonics, which result in the increase of loss and heat. The analysis and calculation of the loss and heat of PMSG become very complicated. Therefore, it is very important to analyze and calculate the loss and heat of PMSG in detail. This thesis, supported by Natural Science Foundation Project of Chongqing, mainly studies the effect of types and control parameters of the converter on the distribution of losses and temperature of PMSG. And a 1.5 MW PMSG is calculated as an example.
Firstly, from the theory of electromagnetic field, the 2D time-stepping finite element model coupled with the circuit was built up. Secondly, the feature of converter was analyzed, and the influences of converter on the harmonics were stated. Thirdly, the calculation methods of the stator harmonic iron loss, copper loss and eddy current loss of rotor permanent magnet were presented. The losses of PMSG were calculated at the RL load, uncontrollable rectifier load and PWM converter load respectively. The characteristics of change are discussed in detail by the comparison. Fourthly, the 2D thermal network model and 2D temperature field finite element model were built up respectively. Furthermore, the temperature distribution of PMSG was got. Finally, the influences of converter types and control parameters on the loss and temperature distribution were discussed.
The results show that, when the direct-driven PMSG operated at the rated speed is connected with uncontrollable converter load, the stator copper loss is biggest, the eddy current loss of permanent magnet is bigger, and the stator iron loss is least. However, when the direct-driven PMSG operated at the rated speed is connected with RL load or PWM converter load, the stator copper loss is biggest, the stator iron loss is bigger, and the eddy current loss of permanent magnet is least. The converter type and control parameters have the significant influence on the loss and heat of PMSG. The maximum temperature appears on the stator upper layer winding at all the conditions.
The results of the thesis are valuable for the design and control of the direct-driven wind PMSG.
引文
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