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对解微分方程算法作了改进,方法是通过对传统微分方程算法在有限时段上进行积分变换,借助积分减少高频分量的影响。通过数字仿真计算验证了改进后算法的优良估计性能,将之与基于微分方程模型的最小二乘法、全波傅里叶算法作了比较。并根据各算法的估计性能特点,提出了一种具有反时限特性的距离保护算法的实现方案。 相似文献
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TDLTE-A信道估计的经典算法有最小平方(LS)算法,线性最小均方误差(LMMSE)算法以及基于变换域的离散傅里叶变换(DFT)算法.LS算法不需要知道信道的先验信息,但是对噪声没有做任何处理.LMMSE算法利用了信道的自相关矩阵,估计性能比LS要优良,但是计算较为复杂,不利于在实际系统中实现.DFT算法则是在LS算法估计结果的基础上,进行变换域处理.但是DFT算法存在较为明显的“地板效应”.然而,提出通过改进TD-LTE-A系统的参数配置,可以有效地改善DFT算法的估计性能,使其性能接近于理想信道估计,并且通过仿真比较了DFT估计与其他信道估计算法在信道响应值的均方误差和信道冲击响应值的差异. 相似文献
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针对传统无迹卡尔曼滤波(unscented kalman filter, UKF)谐波状态估计算法存在时变噪声和异常数据时估计准确度较差的情况,提出了一种基于自适应平方根无迹卡尔曼滤波(square-root UKF, SRUKF)的电力系统谐波状态估计算法。首先,针对时变噪声干扰,引入改进的Sage-Husa噪声估计方法实时估计噪声协方差。其次,针对异常数据干扰,引入异常数据修正方法,通过修正系数来降低异常数据对状态估计结果的影响。最后,通过搭建IEEE14节点系统验证自适应SRUKF算法的估计性能,能够有效地应用于电力系统的动态谐波状态估计。仿真结果表明,该算法在时变噪声和异常数据干扰时仍具有良好的估计性能。 相似文献
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为了提高铅酸电池在随机工况下荷电状态(SOC)估计精度,减小误差变化对估计精度的影响。针对自适应扩展卡尔曼滤波中误差新息序列长度固定选取的局限性,本文提出一种改进的自适应扩展卡尔曼滤波算法估计SOC。通过似然估计来监测协方差匹配算法中的误差新息序列分布变化时刻,根据误差新息的分布变化来自适应调整新息序列长度,进而降低估计SOC时的误差。首先通过带遗忘因子的递推最小二乘法(FFRLS)辨识获得等效模型参数,其模型平均误差电压为13.63 mV,然后在随机工况实验下发现,改进后的算法在估计SOC时的RMSE和MAE性能上精度分别提高了14.44%和17.26%,结果表明改进后的算法拥有更好的稳定性和精度。 相似文献
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A new scheme based on an improved correlation algorithm to distinguish between inrush and internal fault in the transformer is proposed. In this scheme, the current over one cycle of each phase is reorganized as a new measurand. Fault currents can be distinguished from the inrush current if the improved waveform correlation coefficient between the first half-cycle and the latter-half-cycle of the above measurand is over a threshold. Test results show that all types of internal faults, even those accompanied by the magnetizing inrush, can be correctly identified from the inrush with the proposed algorithm. Besides high security, this scheme has satisfactory sensitivity. In addition, this algorithm can be easily implemented in the real-time process. 相似文献
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利用改进型波形相关法鉴别励磁涌流的研究 总被引:20,自引:11,他引:20
提出了一种基于相关分析的变压器励磁涌流识别判据,该判据通过改进的最大面积法重组一周波数据窗内的采样信号,通过比较其前后半周波波的相关性来区分励磁涌流和故障电流。仿真和动模试验表明,该判据能正确识别各种情况下产生的励磁涌流通,在变压器带长线发生内部故障、内部故障与励磁涌流并存及CT特性较差的情况下,仍能快速正确地启动出口动作,具有较好的鲁棒性,该方法算法简单,能在现有的硬件平台上实现。 相似文献
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紧凑型线路具有自然功率大、线路走廊小的特点,经济和社会效益显著,是未来输电技术的重要发展方向。超高压紧凑型线路给传统突变量保护带来的一些特殊的技术问题。分析了超高压紧凑型线路的一些特点及其给传统突变量保护带来的影响,提出了适用于紧凑型线路的突变量保护新方案。新方案采用贝瑞隆模型的波动方程精确计算补偿电压,并利用基于小矢量算法的自适应短窗以检测故障和反映故障暂态特征。在此基础上,提出了综合利用自适应短窗和浮动门槛的突变量保护判据。仿真表明,新方案应用于超高压紧凑型线路上是有效的。 相似文献
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为了改进遗传算法的局部收敛能力,提出了一种新的融合遗传算法和单纯形法的混合遗传算法。该算法兼具遗传算法的全局收敛性和单纯形法良好的局部收敛能力,当遗传算法陷入停滞后,由单纯形法引导进化方向。针对直流输电定电流控制器参数优化的具体问题,设计了一套系统化混合遗传算法寻优方案,并详尽叙述了该方案的流程及具体实现步骤。该方案选取ITAE为目标函数,直流输电准稳态模型为目标函数的计算模型;PI参数的可行域由基于直流输电PSCAD/EMTDC模型仿真的直流电压稳定性计算确定。最后通过CIGRE HVDC Benchmark模型的PSCAD/EMTDC仿真验证所设计参数优化方案的有效性。 相似文献
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介绍了一种单频范围内功率测量的新方法。这种方法是以有效值转换电路实现模拟运算,以程序数据处理实现数字计算,同时利用了新的算法,克服了热电式、时分割式、采样计算式等方法测量音频功率的不足之处。文中定量地给出了这种功率测量方法对测量误差的影响,为单频范围功率的准则测量提供了新途径。 相似文献
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The role of static phase shifters in improving power system stability is investigated. A new technique, based on the nonlinear variable structure control principle, is used to formulate a control algorithm for the static phase shifter. Parameter uncertainty has been considered in the proposed scheme. Computer simulations show that a static phase shifter with the new control scheme has produced significant improvement in power system performance 相似文献
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Lakshmi Dutta Dushmanta K. Das 《International Journal of Adaptive Control and Signal Processing》2021,35(6):991-1016
In this work, an adaptive feedback linearized model predictive control (AFLMPC) scheme is proposed to compensate system uncertainty for a class of nonlinear multi-input multi-output system. Initially, a feedback linearization technique is used to transform the nonlinear dynamics into an exact linear model, thereafter, a model predictive control scheme is designed to obtain the desired tracking performance. A suitable constraint mapping algorithm has been developed to map input constraints to the new virtual input of the proposed control scheme. The proposed control scheme utilizes multiple estimation model and the concept of second-level adaptation technique Pandey et al. (2014) to handle the parametric uncertainty in real-time. Hence, the adaptive term in the control scheme is used to counteract the effect of model uncertainties and parameter adaptation errors. The effectiveness of the proposed AFLMPC control algorithm has been verified successfully in simulation as well as the experimental setup of the TRMS model. The unavailable states of the nonlinear system have been estimated using an extended Kalman filter based state observer. The performance of the proposed control algorithm has been compared with other existing nonlinear control techniques in simulation and experimental validation. 相似文献
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《Electric Power Systems Research》2002,63(1):73-80
This paper presents a new wavelet-based negative-phase sequence (unbalanced currents) protection scheme for synchronous generators. The scheme utilizes the three line voltages and the three line currents available at the generator terminals. Wavelet transform concept is presented. The principle of operation of the algorithm is introduced. Feature extraction technique is derived. Data window necessary for the algorithm is ten samples based on 1200 Hz sampling frequency. Generated data from the simulation of a model power system using emtp were used in the matlab software to test the performance of the technique. The performance under different system conditions is discussed. The results show that the new approach provides robust and accurate classification for a variety of power system conditions. 相似文献