小阻抗支路对潮流计算收敛性的影响和处理

常规潮流算法在应用于含小阻抗支路电网的计算中存在有收敛性问题。通过对含小阻抗支路电网算例的试算分析发现,在当前普通个人计算机性能条件下,使用双精度类型变量,利用高斯赛德尔法迭代两次选取初值后再使用牛顿拉夫逊法,不需要附加处理就可以解决含小阻抗支路电网潮流计算收敛性问题。将该方法应用于三个地区级电网能量管理系统的调度员潮流计算模块,表明所提方法对于解决实际问题的可行性和有效性。     

小阻抗支路对牛顿法潮流的影响及其处理方法

在分析小阻抗支路对牛顿法潮流影响的基础上,结合电力系统的网络的特点,提出了一种选取牛顿法潮流电压初值的新方法－－小阻抗支路零功率法。分析与计算结果表明,中所提方法能够较好地解决牛顿法在计算含有小阻抗支路系统的潮流收敛性问题。     

网络分析中零阻抗支路的处理

在潮流、状态估计等网络分析程序中为区分负荷类型和确定某些开关中的潮流需设置零阻抗支路。通常的处理方式是用小阻抗支路代替零阻抗支路,经验表明在大多数情况下是允许的,但在某些情况下会加大计算误差和使收敛性变坏。因此,高质量的网络分析程序对零阻抗支路需采用专门的处理算法:一是合并其两端的母线,得到状态量后再设法分开母线;二是针对零阻抗支路列出方程和状态量,加入到网络方程中一起求解。这样处理零阻抗支路,既不降低计算精度也不影响收敛性。在华北、华中和华东的160～340母线系统的潮流和状态估计的模拟计算中取得了良好的效果。     

PQ分解法潮流求解含有小阻抗支路系统的收敛性分析

从潮流计算的基本方程出发,通过对迭代过程中小阻抗支路两端电压的幅值和相角的变化规律的分析,得出了PQ分解法潮流计算含有小阻抗支路的系统能够很好收敛的原因.从理论上为求解这类问题找到了快速、可靠的算法.     

PQ分解法潮流求解含有小阻抗支路系统的收敛性分析

从潮流计算的基本方程出发 ,通过对迭代过程中小阻抗支路两端电压的幅值和相角的变化规律的分析 ,得出了PQ分解法潮流计算含有小阻抗支路的系统能够很好收敛的原因。从理论上为求解这类问题找到了快速、可靠的算法     

配电网潮流计算的回路阻抗法

由Ｓ．Ｋ．Ｇｏｗｓａｍｉ等人提出的回路阻抗法是配电网潮流计算的一种有效方法,它处理网处能力较强,收敛性较好,但其节占和支路编号处理复杂。本文研究提出了一种简单可行的节点和支路编号方法,并对其求解过程进行了有效改进,显著提高了其计算速度。     

利用特殊的数据结构和支路电流迭代法计算配电网潮流

本文针对配电网存在的辐射状拓扑结构,Ｒ／Ｘ值较高,ＰＶ节点少等特点引起的牛顿一拉失逊法及ＰＱ分解法不易收敛的问题,提出了利用以支路电流迭代为核心的新算法,并建立了一套适合于配电网的数据结构,提高了计算效率。     

随州EMS系统中对零阻抗支路的改进处理方法

为有效利用母联开关上配备的有功和无功量测,电力系统中的母联开关被抽象成连接在两个母线节点间的零阻抗支路;另外,在有些三绕组变压器的等值模型中,由于中压侧阻抗很小带来计算过程中的数值不稳定性,也可使用零阻抗支路的改进处理方法。深入分析了与零支路相关的各类量测,采用了一种新思路来列写偏导方程,从而在状态估计和潮流计算的处理中根据零支路两侧的相关数据建立对应的雅克比矩阵行。实践证明,该方法提高了数值稳定性,计算结果也更合理。     

一种牛顿潮流算法收敛性定理的应用研究

牛顿拉夫逊(NR)潮流算法是电力系统潮流计算最常用的算法之一,由于NR法具有平方收敛的特性,收敛速度较快,但它对初值选取的要求较高,初值选取对NR法的收敛性能有很大的影响.针对这一问题,分析了一种牛顿潮流算法的收敛性定理,运用此定理可解决因为初值选取不当而造成的潮流发散问题.此外,该定理可进一步评估选择的初值能否保证N...     

The effects of precision and small impedance branches on power flowrobustness

Renewed interest at EPRI on improved power flow techniques is due to the recent improvements in the robustness of fast power flow algorithms. In this paper the authors investigate two interacting parameters which affect convergence in power flow algorithms, limited precision and small impedance branches. Analytical methods and experimental results are given for predicting the minimum convergence tolerance achievable by an algorithm as a function of the infimum of the set of branch impedance values, and the number of bits of mantissa precision. Methods are suggested for increasing the virtual precision at minimal computational cost and for scanning power flow input data to determine whether available precision is sufficient     

改善调度员潮流计算收敛性的措施

就计算条件问题分析了潮流计算不收敛的成因,总结了PV节点和平衡机设置的若干原则,对系统改变运行方式过程中的电压和平衡机监控提出了一些人工干预的经验。根据广东省电力调度中心能量管理系统的实际情况,就状态估计数据对潮流计算的影响作了分析,编写了应用补丁屏蔽状态估计的PV节点配置和电压,实现了PV节点数据的自动保存、这些措施的实施极大地提高了潮流计算的收敛率,保证了调度员潮流应用的运行可靠性,使应用的操控更加以人为本。     

Fast computation and stable convergence technique for unbalanced load flow calculation in large‐scale systems

This paper presents a new method of unbalanced load flow calculation to improve complexity by the method of advanced symmetrical coordinates. Usually, the electric power system has been calculated only by the positive phase sequence component on the assumption that three‐phase transmission lines and loads are balanced. However, many ultrahigh‐voltage transmission lines are not transposed, and therefore mutual inductances cause negative sequence currents in the trunk transmission system. Negative sequence currents cause heating of generators and transformers, and therefore the three‐phase sequence component should be calculated accurately. We examined the fast computation and good convergence performance of unbalanced load flow calculation by models of three‐phase transmission lines, transformers, and loads. The proposed method is not the phase coordinate system but the method of symmetrical coordinates. This technique decreases numerical complexity by the use of a simplified Jacobian matrix. The convergence performance of this method is inferior to that of the usual Newton–Raphson method. As a consequence, the problem of poor convergence performance is alleviated by a technique for the newly developed deceleration Newton method. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(1): 17–24, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21034     

A method of stochastic load flow calculation

Contents The paper presents a new method of the stochastic a.c. load flow calculation. The mathematical model is presented and the equations of solution are derived. The interpretation of the model is discussed and the numerical algorithm for its solution is given.

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Ein verfahren zur berechnung des stochastischen leistungsflusses

Übersicht In der vorliegenden Abhandlung wird eine neue Methode zur Berechnung des stochastischen Leistungsflusses bei Wechselstrom beschrieben. Das entsprechende Modell wird besprochen und seine Deutung wird diskutiert. Die die Lösung beschreibenden Gleichungen und das anzuwendende Algorithmus für die numerische Auswertung werden angegeben.

     

多平衡机潮流计算在调度员潮流中的应用

在调度员潮流中。多平衡机潮流计算比常规潮流计算更加符合电力系统的实际情况。计算结果更为准确。围绕系统不平衡功率的计算,提出了多平衡机潮流计算的三种算法：静态法、准动态法和基于动态潮流理论的动态法。并对每一种算法进行了详细介绍。平衡机群中各平衡发电机进行不平衡功率的分配可以采取多种分配方式。且需要考虑发电机有功出力的限制。对照IEEE14节点标准系统的测试结果表明本文的计算方法是有效、可行的。     

Elimination of floating nodes for load flow calculation

Most approaches aiming at reduction of the power flow computation time approximate the Jacobian matrix. Thus, the convergence is degraded compared to the conventional Newton method. This paper proposes a new approach for reducing the processing time by considering the fact that half of the nodes in real power systems are floating nodes that can be removed. In the conventional reduced matrix approach where the floating nodes are removed, the sparsity is lost. The method in this paper does not remove all of the floating nodes but keeps some nodes by using an optimal criterion for keeping the sparsity. The criterion is to indicate the minimum number of elements in the reduced matrix. This method has been applied to a 1000‐node test system. It was verified that the number of elements of the Jacobian has been reduced to about one‐half that of the conventional matrix. And computation time has been remarkably improved without sacrificing the convergence characteristics for the power flow computation. © 1999 Scripta Technica, Electr Eng Jpn, 129(2): 22–30, 1999