基于dq统一频率变换的电力系统宽频带仿真与分析

随着高比例新能源电力系统的电力电子化特征凸显,电力系统宽频带仿真面临挑战.首先介绍了基于dq统一频率变换建模的基本理论,分析了基于dq统一频率变换建模与准静态相量建模的异同点.而后基于该基本理论,建立了同步发电机、双馈风力发电机和电力网络的多尺度仿真模型.进一步针对系统仿真和分析中的电网高维问题,提出了系统网络简化方法...     

Power system steady state security analysis using vector processingcomputers

The main difficulties encountered in applying a vector processor to the solution of a power flow is the sparsity of the power flow matrices which results in very short vectors when the nonzero terms are gathered into a packed vector format. The authors describe a steady-state security analysis code which overcomes the problem of very short vectors. The length of the list of outages is the major problem in security analysis since it usually includes at least each individual piece of equipment taken one at a time, and a large number of cases with multiple outages. The use of contingency selection and screening has opened the way to reducing this burden, but a very large number of individual cases must be run to satisfy the need to be sure that no cases have gone unchecked. The efforts described have extended the computational speed with which this can be accomplished, and the implementation of very high performance security analysis codes has been made possible     

感应电机空间矢量直接转矩控制系统的效率优化

提出了一种感应电机空间矢量直接转矩控制系统的效率最优控制方法。在定子磁链定向坐标系中,建立了计及铁芯损耗的感应电机数学模型。分析了电机损耗与转矩、转速和定子磁链的关系,推导出了不同运行工况条件下效率最优的定子磁链幅值表达式,实现了感应电机直接转矩变频调速系统的效率最优控制。实验结果表明,所提优化控制策略,在保持直接转矩控制快速动态响应特性的同时,可有效提高电机轻载时的运行效率。     

电力系统的水力模拟

提出电力系统的水力模拟方法。基于模型与系统物理相似或数学相似的模拟是进行电力系统研究的主要方法。电力系统的水力模拟，则是在数学相似基础上的物理系统模拟。通过分析电力系统与水力系统物理量之间的对应关系及实际问题域和求解过程的相似性。提出应用水力网络进行电力网络模拟的研究方法。给出了一个电力系统水力模拟实例。     

Induction machine broken-bar fault diagnosis using the rotor magnetic field space-vector orientation

A new technique based on rotor magnetic field space vector orientation is presented to diagnose broken-bar faults in induction machines operating at steady state. In this technique, stator currents and voltages are used as inputs to compute and subsequently observe the rotor magnetic field orientation, which has a more significant "swing-like" pendulous oscillation in case of broken-bar faults than in healthy operation. It will be shown here that the range of this "pendulous oscillation" is a function of the number of broken bars. Also in this technique, it was found that an inter-turn shorted stator-winding fault, which exhibits similar pendulous oscillation, could be distinguished from rotor broken-bar faults through the use of a variance index. In order to validate this method, experimental evidence is given here for several broken-bar cases in a 2-hp three-phase two-pole squirrel-cage induction machine.     

Power quality analysis using S-transform

This paper presents a new approach for power quality analysis using a modified wavelet transform known as the S-transform. The local spectral information of the wavelet transform can, with slight modification, be used to perform local cross spectral analysis with very good time resolution. The "phase correction" absolutely references the phase of the wavelet transform to the zero time point, thus assuring that the amplitude peaks are regions of stationary phase. The excellent time-frequency resolution characteristic of the S-transform makes it an attractive candidate for analysis of power system disturbance signals. Several power quality problems are analyzed using both the S-transform and discrete wavelet transform, showing clearly the advantage of the S-transform in detecting, localizing, and classifying the power quality problems.     

华电滕州新源热电有限公司150MW机组EH系统改造

上海汽轮机厂C150-13.24/0.981/535/535机组EH系统在我公司安装以来,曾多次发生由于伺服阀卡涩造成高压主汽门无法进行定期活动试验,高调门运行中无法调整负荷以及在开机时无法打开调门影响开机等缺陷。在多方调研,计算、论证的基础上,对EH系统进行改造,加装了在线滤油装置和冷却装置。系统改造后,至今没有出现伺服阀卡涩现象,机组运行状况良好,保障了机组的安全稳定运行。     

The application of space-vector theory to the analysis of electrical machines with space harmonics

Contents In the present paper the space vector method is described for the analysis of uniform air-gap three-phase and two-phase machines, taking into account the effects of m.m.f. space harmonics.The space vector equations are established in a natural and also in an arbitrary reference frame. It is shown that the various harmonic models can obtained without performing matrix transformations. The relationship between matrix and space vector forms is discussed. The models derived are suitable for both steady-state and transient analysis. Methods of derivation of harmonic transformations are also presented.

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Die Anwendung der Raumzeigertheorie zur Analyse elektrischer Maschinen mit räumlichen Obserwellen

Übersicht In der vorliegenden Arbeit wird die Methode der Raumzeiger zur Darstellung räumlicher Oberwellen in elektrischen Maschinen betractet. Die allgemeinen räumlichen Vektorgleichungen werden in einem natürlichen bzw. in einem beliebigen Koordinatensystem beschrieben. Es wird gezeigt, daß die verschiedenen harmonischen Modelle ohne Matrizenoperationen erhalten werden können. Die Beziehungen zwischen den Matrizen- und Raumzeiger-schreibweisen werden untersucht. Die Darstellungen der Maschine sind für die Analyse stationärer und nichtstationärer Vorgänge anwendbar. Schließlich wird die Ableitung harmonische Transformationen berücksichtigt.

     

Power system model reduction using identification techniques

Identification techniques are applied to the construction of lower order nonlinear power system equivalents which can be used in stability calculations, and simulation of dynamic and transient conditions of a multimachine power system. Development of an equivalent machine for a group of dissimilar machines operating at a generating station is considered. An efficient algorithm based on the minimum principle to determine the parameters of the equivalent model which is lower in order than the actual system is also presented.     

Power system operations scheduling using separable programming

The problem of electric power operations scheduling comprises maintenance scheduling, intermediate- and short-term hydro-thermal scheduling, unit commitment and production scheduling. Recognizing the inter-relationship among these subproblems, the effect on one another is analyzed. Computationally efficient formulations and algorithms for maintenance scheduling and intermediate- and short-term hydro-thermal scheduling are presented.A variation of the separable programming technique is presented. This results in a linear programming formulation of the nonlinear scheduling problem. This technique is applied to a hypothetical system containing nuclear, fossil, hydro-electric and pumped-storage units. The large problem of hydro-thermal scheduling due to the inclusion of a nuclear unit is decomposed into two stages. In the first stage, the relatively stable nuclear generation is optimized with respect to the generation from large fossil-steam units. Hourly generation levels for all units in the system are then determined in the second stage.     

惠州供电局短信系统的升级改造

随着国民经济快速发展,用电需求不断攀升,电力供求矛盾日益尖锐。在这种情况下,各用电企业千方百计从行政、经济和技术上加强管理,做好供电优质服务工作。文章主要介绍惠州供电局在现有省公司短消息系统平台的基础上,改造具有惠州特色的短信系统——错峰预警信号系统,实现错峰用电动态管理,在错峰用电工作中发挥强大的有值服务功能。     

利用多小波的电力系统信号重构分析

以电力系统故障电压信号为原始信号,通过对不同预/后处理方法的多小波自身重构误差比较和基于不同预/后处理方法的整个多小波变换过程中的重构误差分析,详细讨论了影响多小波重构精度的因素.通过对不同预/后处理方法的多小波分解结果的对比,以及对不同类型信号的多小波与传统小波的重构误差的详细比较和讨论,认为多小波比传统小波更适合于对信号的精确重构,适合用于对电力系统暂态故障信号的处理.     

基于LabVIEW的电能质量分析系统

在论述虚拟仪器概念、特点的基础上,通过实例阐述了在LabVIEW平台下进行电能质量分析。本文对实验数据通过动态数据交换技术(DDE)实现LabVIEW与Excel数据交换,着重对电能质量的3个重要指标:电压波动、谐波和三相电压不平衡度进行分析看其是否符合国家标准同时验证使用LabVIEW软件开发电能质量分析仪的高效快速性。     

一种考虑变电站内部的电力系统可靠性分析

将变电站视为等值节点的传统可靠性分析方法忽略了变电站内部结构对系统的影响。将系统划分成设备层、变电站层、主网层,利用蒙特卡洛方法进行分层抽样;通过马尔科夫状态空间方程和隐性故障模型计算站内设备和保护功能组状态概率,并对其进行抽样;采用基于邻接矩阵的最小割集算法求得变电站预想事故集,并与抽样结果进行对比,生成变电站停运线路集,将其合并到电网抽样结果中,计算系统可靠性指标。通过修改的RTS测试系统对终端变供电网络进行仿真校验。结果表明,所提方法实现了继电保护失效影响下变电站内部结构和设备停运对系统可靠性影响的定量分析。     

应用Matlab进行电力系统分析和动态仿真

Matlab中的电力系统模块PSB(Power System Blockset)是专门为电力系统设计的仿真分析软件,其功能十分强大。首先介绍了其中的模型,然后在仿真平台Simulink上利用PSB进行了励磁自动控制系统的设计和仿真、发电机并网的分析和动态过程仿真,得到了较满意的仿真结果。     

基于LIF法的励磁系统参数辨识

介绍了一种采用线性积分滤波器(LIF)的连续时间辨识方法,借以辨识励磁系统参数,使用线性积分滤波器可以完全消除积分方程初始条件的影响,即在非零初始条件下无需辨识初始条件依然能得到精确的结果。在仿真研究中,以IEEEAC1A型标准励磁系统为例采用LIF法进行了参数辨识。     

Power system topological observability analysis including switchingbranches

The conventional topological observability analysis based on the network representation at the bus-branch level is generalized to include the explicit modeling of circuit breakers and switches. This generalization is motivated by the present trend toward a more detailed representation (at the substation level) of the power network in state estimation studies. After developing the topological representation of switching branches according to their current status, it is shown that existing algorithms for observability and criticality analysis can be adapted to solve the extended problem. Results of the proposed approach for generalized observability and criticality analysis are validated by checking their consistency with numerical state estimation results     

Power system stability enhancement using static phase shifter

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     

Power system probabilistic security assessment using Bayes classifier

This paper presents a method for power system security assessment based on the Bayes classifier. This method can be applied to calculate probabilistic security indices as well as on-line security assessment. In general, the determination of security breach is a cumbersome and time-consuming process due to dynamic and steady-state effects. These effects can be incorporated by considering transient stability, satisfaction of system load without violation of constraints, and voltage stability studies. The variation of the system load, as well as contingencies, may cause system transition to a different operating state. It is impractical if not impossible to evaluate all these situations, such as contingencies resulting from load variation. The straightforward Monte Carlo simulation, one of the possible methods in power system reliability analysis, requires the evaluation of a system operating state for each sampled state and is computation-intensive. In the proposed method, first the joint probability density of feature vectors has been obtained by using some training data. Once this joint distribution is obtained, the Bayes classifier provides the assessment of system security without complicated contingency analyses and can reduce the computational burden. Security status of a given feature vector can be determined by a posteriori probability rule called Bayes rule, which can be implemented in on-line security assessment or power system reliability studies.     

Power system stability enhancement by static var system using self-commutated inverters

This paper deals with static var compensators using self-commutated inverters (which is so-called SVG) compared with conventional SVC and Rotary Condenser. Improvement of power system stability is explained by using simple system model and checked by dynamic digital simulation. In the latter part of this paper, system outline, basic specifications and control diagram of the SVG rated 154 kV, ±80 MVA, which has been installed at INUYAMA Switching Station, are briefly presented. Field tests at INUYAMA verify that power swing is effectively damped and transmission capacity is increased.