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This paper presents an optimal coordinated voltage control scheme for preserving long-term voltage stability of power systems. Linear quadratic integral (LQI) controller is employed to construct this scheme. Also, this paper considers the detailed dynamic model of doubly-fed induction generator (DFIG) wind turbine, synchronous generators, over excitation limiter (OEL) and under-load tap changer (ULTC) system, which are important elements influencing voltage stability of power systems. The proposed approach at each time instance involves following two major steps: First, the power system nonlinear equations are linearized and optimal controllers are obtained by LQI technique. Then, in the second step the system dynamic behavior is investigated via time-domain simulations by applying the attained optimal control signals at the first step. The impact of the proposed coordinated voltage control scheme is evaluated by time domain simulations on a well-known test system, under variable wind speed and fault conditions. 相似文献
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对于病险水库除险加固成本的确定多依据标准和规范,定性确定,缺乏定量的论证。生命质量指数(Life quality index, LQI)是一个复合的社会指数,能较好地结合工程当地的经济发展水平,从社会效应的角度来优化风险和除险加固投入。将风险分析和LQI引入到病险水库除险加固决策优化过程中,结合已有溃坝资料,提出了溃坝生命损失的快速估算公式,在当前规范的基础上,建立了病险水库除险加固效应的定量评价模型。以华东某均质病险土坝为例,分析了除险加固前后该坝的渗透失稳风险,估算了溃坝生命损失;根据工程当地的社会、经济发展水平、生命质量指标参数,计算出了该坝除险加固的以LQI衡量的费用效益比和最大社会愿意支付费用,验证了文中方法的有效性。 相似文献
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现有基于链路质量指示(LQI)的估计方法未能有效解决LQI参数波动较大的问题,并且所使用的LQI与收包率(PRR)的映射关系模型没有考虑实际物理意义。为此,通过推理LQI和PRR的理论关系,建立更具实际物理意义的双曲正切模型,并提出一种链路质量估计方法。通过指数加权卡尔曼滤波获得更为稳定的LQI估计值,再利用双曲正切模型对链路质量进行定量估计。实验结果表明,该方法能够更真实地反映链路质量,与LETX、K-CCI方法相比,其估计误差在不同质量链路下降低了11.21%~52.26%。 相似文献
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基于RSSI和LQI的动态距离估计算法 总被引:13,自引:0,他引:13
本文提出了一种基于RSSI和LQI的动态距离估计算法.其思想就是通过对无线电传播路径损耗模型以及大量实测数据的分析,用分段线性逼近的方法得到RSSI、LQI这2者与传播距离的衰落曲线.在距离估计时,分别对这2条衰落曲线计算出估计距离,并动态地进行优化处理得到最终的距离估计值.算法在基于ZigBee的硬件平台上进行,证明了该算法较普通的基于RSSI的测距方法有了明显的进步,提高了距离估计的精度,并且适合在通信开销小、硬件要求低的节点上应用,有利于提高基于RSSI测距的定位算法的精度. 相似文献
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A balance differential equation between free time and money-producing work time on the national economy level is formulated in a previous paper in terms of two dimensionless quantities, the fraction of work time and the total productivity factor defined as the ratio of the Gross Domestic Product to the total salary paid in return for work. Among the solutions there is one relation that compares surprisingly well with the relevant sequences of Danish data spanning from 1948 to 2003, and also with similar data from several other countries except for slightly different model parameter values. Statistical analysis reveals a data structure that allows the formulation of a simple stochastic model for the development of the data sequences with the year. Simulations with the stochastic model show sample curve behavior of the same fluctuating appearance as the factual data. This indicates that there are no other significant systematically balance influencing parameters on the macro economical level than those considered in the definition in the previous paper of the Life Quality Time Allocation Index. 相似文献
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基于LQI的节点测距实验研究 总被引:1,自引:0,他引:1
为了增强测量系统中的线性度和精度,将LQI测距法应用于室内定位系统中.在基于ZigBee的硬件平台上,结合室内环境进行了测距实验,并建立了经验模型.实验结果表明,LQI在短距离测量中有较好的线性度和精度,在室内测距的应用中效果较好. 相似文献
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无线传感器网络链路通信质量测量研究 总被引:14,自引:1,他引:14
首先分析了传统链路测量方法所存在的问题,提出了均值RSSI(接收信号强度显示)、均值LQI(链路质量显示)测量法,通过测量及计算RSSI、LQI的均值,可以较为准确地获得链路通信质量信息;其次构建了发送功率改变、硬件校准改变、周围环境改变和并发干扰等实验案例,分析了均值RSSI、均值LQI在上述案例下的测量性能,定义了链路测量灵敏度,计算了均值RSSI、均值LQI的灵敏度值,对RSSI及LQI用于链路通信质量测量和性能评估做出了全面的权衡。 相似文献