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配网动态重构的静态解法 总被引:1,自引:0,他引:1
提出一种解决配网动态重构问题的静态方法.该法不仅求解简单,而且能充分利用现有的静态方法来实现时变系统的动态重构.首先,文章对静态重构的目标函数进行改进,使其能够求解一个时间区间内的最优结构.然后在整个时间区间内用枚举法确定最优的重构时间,完成区间内的一次动态重构.最后用逐次逼近法来调整各次重构的时间和结构,实现区间内的多次优化.在修改过的IEEE 33节点上验证了所提方法的正确有效性. 相似文献
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基于最优乘子潮流确定静态电压稳定临界点 总被引:4,自引:9,他引:4
给出了一种基于最优乘子潮流求静态电压稳定临界点的新方法.与连续潮流或直接法求解电压崩溃点不同,该方法从潮流的可行域外出发,利用潮流迭代过程中最优乘子的值和最小二乘解提供的信息,沿注入功率变化的方向逼近电压崩溃点.给出了判别和计算鞍结型和约束诱导型分岔点的方法,分析了逼近过程中的各种可能情况.对多个算例测试的结果表明:所提出的方法通过几次迭代即可收敛于静态电压稳定临界点,计算结果与应用连续潮流和直接法一致. 相似文献
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针对频域法构造小波滤波器方法较少、稳定性无法保证、逼近精度不高等问题,基于天牛须搜索算法提出了一种小波滤波器直接频域逼近方法.首先根据小波滤波器电路的基本要求设计逼近有理式,然后加入电路实现所需的稳定性、正实性和初值为零的约束条件,建立小波滤波器逼近的频域优化模型.再以高斯小波和Marr小波为例,使用天牛须搜索算法求解... 相似文献
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提出一种解决配网动态重构问题的静态方法。该法不仅求解简单,而且能充分利用现有的静态方法来实现时变系统的动态重构。首先,文章对静态重构的目标函数进行改进,使其能够求解一个时间区间内的最优结构。然后在整个时间区间内用枚举法确定最优的重构时间,完成区间内的一次动态重构。最后用逐次逼近法来调整各次重构的时间和结构,实现区间内的多次优化。在修改过的IEEE 33节点上验证了所提方法的正确有效性。 相似文献
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提出了一种采用改进的最近电平调制技术(nearest level modulation,NLM)的叠加逼近调制策略,能够抑制模块化多电平换流器(modular multilevel converter,MMC)的谐波环流。首先对基于传统NLM的MMC进行解析分析,指出当采用传统NLM时,上、下桥臂电压的实际输出值与控制器参考电压之间会出现偏差,且偏差中的二倍频成分是产生二倍频环流的根本原因。据此,提出了一种叠加逼近调制策略,使上、下桥臂实际输出电压与参考值一致,并从能量平衡角度论证了当采用叠加逼近调制策略时,桥臂中无二倍频环流。以厦门柔直示范工程的电磁暂态仿真算例验证了所提算法的正确性,为下一步的实际工程应用奠定了基础。 相似文献
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基于零空间的现代内点最优潮流新算法 总被引:1,自引:0,他引:1
在约束条件苛刻时,现代内点法求解电力系统最优潮流OPF问题有时不收敛,为克服此不足,本文提出一种求解OPF问题的零空间内点算法。首先分析了现代内点法不收敛的原因;然后通过改进的原始对偶变量的修正方法和终止准则来保证迭代点的最优性和不等式约束的互补性;最后将所提方法用于求解5个IEEE标准算例。数值结果表明,所提算法与现代内点法求解OPF问题的结果一致,在约束条件苛刻时,本文算法具有更好的收敛性。 相似文献
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本文应用数值逼近方法分析调速器静特性所得的结论与采用数值统计原理的一元线性回归法分析调速器静特性所得的结论一致,且其物理意义清晰,易于推导和记忆,便于推广和计算机编程。 相似文献
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为了解决线性潮流计算方法无法处理PV节点的问题,提出了一种含PV节点的配电网线性潮流计算方法。所提方法从极坐标的牛顿-拉夫逊法潮流计算的节点功率方程出发,利用配电网的特征对节点功率方程中的非线性项进行线性近似处理,得出一种线性潮流方程。所提方法不仅适用于弱环网络,还克服了大多数线性潮流计算方法无法处理PV节点的缺陷。算例分析表明,以牛顿-拉夫逊法潮流计算结果作为基准,所提方法的最大误差的数量级保持在10~(-4),计算精度与计算效率满足配电系统快速分析的要求。 相似文献
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Chengtao Wen Shuning Wang Hao Zhang Muhammad Junaid Khan 《International Journal of Circuit Theory and Applications》2005,33(1):87-97
A new compact MAX representation for 2‐D continuous piecewise‐linear (PWL) functions is developed in this paper. The representation is promising since it can be easily generalized into higher dimensions. We also establish the explicit functional form of basis function and demonstrate that the proposed basis function is the elementary ‘building block’ from which a fully general 2‐D PWL function can be constructed. In addition, we reveal the relationship of basis function with minimal degenerate intersection and Hinging Hyperplane, which shows that the MAX model can unify Chua's canonical expression, Li's representation, lattice PWL function and Bremann's Hinging Finding Algorithm into one common theoretical framework. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Lorenzo Repetto Marco Storace Mauro Parodi 《International Journal of Circuit Theory and Applications》2003,31(3):299-313
In this paper, we face the problem of model reduction in piecewise‐linear (PWL) approximations of non‐linear functions. The reduction procedure presented here is based on the PWL approximation method proposed in a companion paper and resorts to a strategy that exploits the orthonormality of basis functions in terms of a proper inner product. Such a procedure can be favourably applied to the synthesis of the resistive parts of cellular non‐linear networks (CNNs) to reduce the complexity of the resulting circuits. As an example, the method is applied to a case study concerning a CNN for image processing. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Janne Roos 《International Journal of Circuit Theory and Applications》2005,33(2):109-134
Simplex‐based piecewise‐linear (PWL) approximations of non‐linear mappings are needed when the robust PWL analysis is used to directly solve non‐linear equations. This paper proposes a straightforward technique for transforming the well‐known approximations into another form. This new form is computationally more efficient, since it preserves the sparse structure of the original Jacobian matrix. Furthermore, this new form of PWL approximation explicitly relates the simplex‐based PWL analysis to the conventional formulation of the Katzenelson algorithm. The proposed transform technique is also extended to treat groupwise‐separable mappings and, finally, non‐separable but sparse mappings that arise in real‐life simulation of large electronic circuits. In this paper, all these (transformed) simplex‐based PWL approximations are compared in terms of their generality and efficiency. The computational efficiency of the PWL approximation that utilizes sparsity is validated with realistic simulations. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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A linear programming approach to online set membership parameter estimation for linear regression models
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M. Casini A. Garulli A. Vicino 《International Journal of Adaptive Control and Signal Processing》2017,31(3):360-378
This paper presents a new technique for online set membership parameter estimation of linear regression models affected by unknown‐but‐bounded noise. An orthotopic approximation of the set of feasible parameters is updated at each time step. The proposed technique relies on the solution of a suitable linear program, whenever a new measurement leads to a reduction of the approximating orthotope. The key idea for preventing the size of the linear programs from steadily increasing is to propagate only the binding constraints of these optimization problems. Numerical studies show that the new approach outperforms existing recursive set approximation techniques, while keeping the required computational burden within the same order of magnitude. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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分析比较了网络约化模型下电力系统动态安全域的3种线性近似方法的综合效能,分别为:基于稳定域二次近似的动态安全域线性近似(Q线性近似)、基于稳定域线性近似的动态安全域线性近似(L线性近似)和基于稳定域边界法向量恒定假设的动态安全域近似(L0线性近似)。其共同之处为在事先搜索而得的处于动态安全域边界的临界点处应用相应的近似刻画方法。文中以最小二乘拟合搜索得到的临界点所获得的线性近似为基准,分析比较了上述3种线性近似对安全域边界刻画的准确程度;特别是对于低雏的动态安全域,以搜索获得的真实动态安全域为基准,采用图示方法直接比较不同线性近似的近似程度。仿真分析表明:在具有事先搜索的临界点时,3种线性近似方法均能准确地近似动态安全域的局部边界;同时,L0线性近似和L线性近似计算量小,更适用于大型电力系统。 相似文献
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Irwin W. Sandberg 《International Journal of Circuit Theory and Applications》2000,28(2):109-120
It is known that large classes of approximately‐finite‐memory maps can be uniformly approximated arbitrarily well by the maps of certain non‐linear structures. As an application, it was proved that time‐delay networks can be used to uniformly approximate arbitrarily well the members of a large class of causal nonlinear dynamic discrete‐time input–output maps. However, the proof is non‐constructive and provides no information concerning the determination of a structure that corresponds to a prescribed bound on the approximation error. Here we give some general results concerning the problem of finding the structure. Our setting is as follows. There is a large family 𝒢 of causal time‐invariant approximately‐finite‐memory input‐output maps G from a set S of real d‐vector‐valued discrete‐time inputs (with d⩾1) to the set of ℝ‐valued discrete‐time outputs, with both the inputs and outputs defined on the non‐negative integers 𝒵+. We show that for each ϵ>0, any Gϵ𝒢 can be uniformly approximated by a structure map H(G, ·) to within tolerance ϵ, and we give analytical results and an example to illustrate how such a H(G, ·) can be determined in principle. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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为了响应配电系统快速分析的需求,提出了一种考虑PV节点的配电网三相线性潮流计算方法。根据配电网自身的特性,对极坐标形式的节点功率方程中的非线性项进行线性近似处理,并利用导纳矩阵的性质对节点功率方程进行化简,得到一种线性的节点功率方程。基于线性的节点功率方程,建立了一种考虑PV节点的配电网三相线性潮流计算模型。所提线性计算模型不仅考虑了PV节点,还适用于弱环配电网络,通用性较强。最后以牛顿-拉夫逊法潮流计算结果作为基准,通过33节点配电系统算例分析表明:所提方法的计算误差满足配电系统快速分析要求,与现有的线性潮流计算方法相比,具有更高精度。 相似文献