基于最优占空比的风力发电机MPPT方法研究

针对目前已有的最大功率跟踪(MPPT)控制方法的不足,为提高风力发电的最大风能利用效率,根据风力发电机和boost变换器的输出特性,在变风速条件下,通过给定最佳机械转矩,直接计算最优占空比,控制风机电磁转矩,实现最大功率追踪控制.针对GP-300和FD-5型直驱式永磁风力发电机,进行功率跟踪控制仿真实验,实验结果表明所提出方法的有效性和可靠性,并具有良好的工程应用前景.     

基于网络控制的电机软启动器故障分析与控制系统改造

某公司低压电机应用某合资品牌软启动器配合网络完成启停及反馈控制方式,正常运行时频繁发生软启动器无故障报警停机。针对这一现象进行深入分析、总结,并对其进行国产化改造,以保证设备运行可靠性及生产的稳定性。     

支持CRM分析的数据仓库多维启动模型

CRM是一种整合了知识管理、数据挖掘及数据仓库技术的商业策略,旨在支持制定决策来保留长期有利的客户关系。分析了CRM中数据仓库的设计问题,提出一种支持CRM分析的强劲的多维启动模型。为验证此模型,用一些CRM的查询进行测试,并定义两个量:成功率和适配率来评估。实验结果表明,此启动模型具有很高的成功率和适配率,可用于客户收益分析、市场收益分析、产品收益分析、渠道收益分析等多种收益分析。     

大功率电机启动方式的比较与选择

通过对电机启动过程的分析和启动方式的比较,说明大功率电机的启动应选用降压启动方式。软启动器作为新型的降压启动装置,以其优良的性能和良好的控制方式,将得到广泛的选用。     

基于87C196MC单片机的矿用隔爆型软起动器的研究

根据在煤矿井下工作的660V/1 140 V交流电动机起动电流大,对电网及电机造成冲击的缺点,设计了一种新型的矿用隔爆型软起动器。文章着重介绍了以87C196MC单片机为控制核心的控制系统硬件电路及软件设计。针对隔爆箱体积小、强弱电相互干扰严重、功率元件散热性差的缺点,相应的设计了精简的硬件电路、采用了硬件与软件的抗干扰措施。该软起动器具有软起动、软停车、漏电保护等近10种保护功能,充分地保证了交流电动机在煤矿井下的正常使用。     

有待用风电机组且传输受限电网的源网协调调度方法

随着大规模风电场的建设和并网,电源(风电)与电网之间的尖锐矛盾逐渐显现。一些电网由于输电能力的限制,导致部分新建机组不能并网或已投运风电机组弃风,这种电网被定义为有待用风电机组且传输能力受限的电网。对于电网调度员来说,只有入网风电机组的装机容量是可调度的。由于风电的波动特性,即使知道用于传输风电的电网传输空间,也难以决定应该接入多少风电机组以充分利用电网传输空间。文中通过对风电波动特性的分析,提出了源网协调调度方法。该方法可在保证电网安全的条件下,最大限度地利用电网用于传输风电的空间,以提高电网和风能利用率。     

A Comparison of Four Precipitation Distribution Models Used in Daily Stochastic Models

Stochastic weather generators are statistical models that produce random numbers that resemble the observed weather data on which they have been fitted; they are widely used in meteorological and hydrological simulations.For modeling daily precipitation in weather generators,first-order Markov chain-dependent exponential,gamma,mixed-exponential,and lognormal distributions can be used.To examine the performance of these four distributions for precipitation simulation,they were fitted to observed data collected at 10 stations in the watershed of Yishu River.The parameters of these models were estimated using a maximum-likelihood technique performed using genetic algorithms.Parameters for each calendar month and the Fourier series describing parameters for the whole year were estimated separately.Bayesian information criterion,simulated monthly mean,maximum daily value,and variance were tested and compared to evaluate the fitness and performance of these models.The results indicate that the lognormal and mixed-exponential distributions give smaller BICs,but their stochastic simulations have overestimation and underestimation respectively,while the gamma and exponential distributions give larger BICs,but their stochastic simulations produced monthly mean precipitation very well.When these distributions were fitted using Fourier series,they all underestimated the above statistics for the months of June,July and August.     

响应面法优化纯种根霉米粉种曲制作工艺

针对纯种根霉（Rhizopus）米粉种曲制备过程中缺乏系统控制、质量难以稳定的问题,研究其关键影响因素,优化种曲的制备工艺。以一级籼米米粉为原料,接种纯种根霉制备种曲,在单因素试验的基础上,以种曲的试饭糖分值为响应指标,利用Box-Behnken响应面设计试验优化种曲制作工艺,确定纯种根霉米粉种曲的最佳制备工艺为试管菌种培养时间72 h、二级种曲培养温度32 ℃、米粉水分含量25%。在此最佳工艺条件下进行验证试验,实际测得种曲的试饭糖分平均值为27.18 g/100 g,与模型的理论预测值非常接近,拟合成功;该模型优化工艺可为纯种根霉曲的生产提供参考。     

Simulation of aerodynamic performance affected by vortex generators on blunt trailing-edge airfoils

An investigation was carried out by numerical simulation on a wind turbine airfoil and a blunt trailing-edge airfoil with and without vortex generators (VGs), and the performance of the airfoils was analyzed. By the simulation of airfoil DU 91-W2-250 it was verified that the numerical method and model were credible. Based on this airfoil, a new one with a blunt trailing edge of 6% chord was blended by symmetrically adding thickness, and its characteristics curves were obtained through computing at key angle...     

电网对称故障时双馈感应发电机低电压穿越控制

分析电网对称故障时,双馈感应风力发电机定子磁链变化过程、导致定转子过电流的原因、电网故障发生具体时刻及故障程度对双馈感应发电机定转子的影响,提出一种双馈感应风力发电机转子侧变换器低电压穿越控制策略,改善了双馈感应发电机在电网故障时定、转子过电流的情况,实现了双馈感应发电机在电网对称故障时的低电压穿越.在理论分析基础上,建立双馈感应发电机转子侧变换器低电压穿越控制模型和3 kW双馈感应发电机励磁变换器低电压穿越控制实验系统.实验结果表明,所提出的双馈感应发电机低电压穿越控制策略动态响应快、方法行之有效.