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适用于风力发电的一种低成本VSG实现方法 被引量:8
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作者 胡书举 李建林 +1 位作者 梁亮 许洪华 《电气应用》 北大核心 2007年第11期50-53,共4页
新的电网导则要求风力发电系统具有一定的低压度过能力(LVRT),采用一种低成本的电压跌落发生器(VSG)方案,可以方便地模拟电网电压跌落。以单片机作为控制器,以晶闸管作为交流开关,以MOC3062作为晶闸管驱动器,构成变压器形式的单相VSG,... 新的电网导则要求风力发电系统具有一定的低压度过能力(LVRT),采用一种低成本的电压跌落发生器(VSG)方案,可以方便地模拟电网电压跌落。以单片机作为控制器,以晶闸管作为交流开关,以MOC3062作为晶闸管驱动器,构成变压器形式的单相VSG,省去了同步电路,因而结构和控制简单,可扩展性强,成本低,可靠性高,能够实现大功率等级。仿真和实验结果表明电压衔接良好,波形畸变小,可以满足风电测试的需求。 展开更多
关键词 低压度过 电压跌落 电压跌落发生器 单片机 晶闸管 MOC3062
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Grain refinement of as-cast superalloy IN718 under action of low voltage pulsed magnetic field 被引量:13
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作者 李应举 马晓平 杨院生 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第6期1277-1282,共6页
The grain refinement of superalloy IN718 under the action of low voltage pulsed magnetic field was investigated. The experimental results show that fine equiaxed grains are acquired under the action of low voltage pul... The grain refinement of superalloy IN718 under the action of low voltage pulsed magnetic field was investigated. The experimental results show that fine equiaxed grains are acquired under the action of low voltage pulsed magnetic field. The refinement effect of the pulsed magnetic field is affected by the melt cooling rate and superheating. The decrease of cooling rate and superheating enhance the refinement effect of the low voltage pulsed magnetic field. The magnetic force and the melt flow during solidification are modeled and simulated to reveal the grain refinement mechanism. It is considered that the melt convection caused by the pulsed magnetic field, as well as cooling rate and superheating contributes to the refinement of solidified grains. 展开更多
关键词 SUPERALLOY grain refinement low voltage pulsed magnetic field cooling rate SUPERHEATING
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