Abstract —— In order to improve adaptability for wind power gridconnected converter under non-ideal grid conditions and reduce the harmonic influence, harmonic suppression mechanism for grid-connected converter is depth analyzed and harmonic suppression method and theory is derived. Be limited by complexity of the control system, compound control strategy composed by repetitive controller paralleled with PI controller is proposed for grid-connected converters control in this paper. System stability is analyzed, Geometric representation for repetitive controller stability is shown in figure and Control system difference equation is deduced. Using the proposed control strategy, no difference tracking current control is achieved in the fundamental positive sequence reference frame. The gird current harmonic can be effectively reduced and the
converter grid adaptability is improved. The simulation and experimental results verified the effectiveness of the proposed control strategy.
2021-08-26 14:08:24
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弱电网中当远端发生严重电压跌落故障时，低电压穿越(LVRT)控制策略可能会导致双馈风机并网系统出现稳定问题。为此，首先建立了故障期间系统的准稳态模型，基于相平面法揭示了因平衡点不存在导致的系统大干扰失稳机理，并分析了电压跌落程度、线路阻抗幅值和相角以及无功电流控制增益系数等关键影响因素。然后，建立了LVRT期间系统的小信号模型，并分析了LVRT控制策略中转子电流参考值动态对系统小干扰稳定的影响。研究表明，忽略转子电流参考值动态会导致小干扰稳定分析结果偏乐观。
2021-07-11 16:38:53
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将三相不对称的交流电源用正序和负序电压表示,用傅里叶分析方法计算了正序和负序电压传递到直流侧的谐波电压的规律,将这一理论应用到基于感应滤波的直流输电系统,计算在交流系统故障时,直流侧电压谐波的数学表达式,比较在同样的交流系统故障条件下,基于感应滤波的直流输电系统在抑制直流侧谐波幅值方面优于传统的直流输电系统,最后参考实验室基于感应滤波的直流输电系统模型,对输电系统在交流系统故障下的直流电压谐波进行了动模实验.结果表明,由于在感应滤波换流变压器的第三绕组接入2,11,13次LC滤波器,使直流电压中含量高的低
2021-06-12 12:22:03
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重介质旋流器用离心式渣浆泵磨损机理分析
对重介质旋流器用离心式渣浆泵过流部件的磨损部位和磨损过程进行了分析，提出了磨损过程的三个阶段，利用水流动力学磨粒磨损、汽蚀磨损、氧化磨损的理论分析了过流部件的磨损机理，并提出 了减轻磨损的途径。
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2021-03-13 09:08:56
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