动态负荷模型比例对电网稳定性影响分析

综合负荷模型对电力系统的暂态稳定性具有复杂的影响。以河南电网为例,采用暂态安全定量分析软件FASTEST计算了不同动态负荷模型比例时的暂态功角稳定裕度和临界切除时间。仿真计算表明动态负荷模型比例的调整会引起电网失稳模式的变化,且在不同失稳模式下,其对电网稳定性的影响不同。因此不应脱离具体情况泛论动态负荷模型对稳定性的影响。     

河南电网送端和受端负荷模型对稳定极限的影响

分析了感应电动机负荷和恒阻抗负荷在暂态过程中的动态响应特性,说明负荷模型主要是通过有功特性对功角稳定性产生影响。通过对河南电网送端和受端负荷模型的调整及断面稳定极限的仿真计算,指出受暂态功角稳定性影响的送、受端断面稳定极限随电动机负荷的比例及定子电抗参数的变化而变化,且当相同的模型分别处于送端和受端时,其对暂态功角稳定性的影响不同。介绍了河南电网负荷特性数据库的建设和负荷模型测辨结果的应用情况,对今后的负荷模型分析和实测工作进行了展望。     

重庆电网多种负荷模型对系统稳定性影响机理

负荷特性是电压失稳过程中最活跃、最关键的因素,对于电压稳定研究具有重要意义。通过典型故障后电压恢复特性比较分析,研究了负荷特性和组成比例对系统故障后电压恢复特性的影响;通过计算典型故障极限切除时间,分析了负荷特性和组成比例对重庆电网系统稳定性的影响。经过计算可以得到,针对重庆电网的异步电动机负荷比静态负荷模型更有利于系统电压稳定。     

基于感应电动机的暂态电压失稳分析

采用典型系统分析了暂态电压失稳现象。当系统负荷中包含感应电动机且达到一定比例时,暂态电压失稳现象就可能出现。电动机负荷所占比例越高、载荷率越大,越易发生暂态的电压失稳,负荷中电动机的比例对暂态稳定的故障临界切除时间有着较为明显的影响。详细分析了负荷中电动机的比例对暂态失稳模式和故障临界切除时间影响的原因,最后用某电力大系统中的暂态电压稳定仿真验证了上述结论。研究表明,电动机负荷特性和比例对系统暂态稳定有着明显影响。     

负荷模型对山东电网短路电流计算影响研究

"十三五"期间,特高压交直流将大规模入鲁,山东电网网架结构越来越密集,短路电流水平成为影响山东电网规划的重要因素,甚至影响宏观规划决策。介绍了目前国内常用的短路电流计算程序对负荷模型的处理,以及国内各规划运行单位在短路电流计算中对负荷模型的选择,推导分析了输电网故障时接于配电网的感应电动机负荷向输电网贡献短路电流的机理。最后以枣庄电网为例,分析了不同负荷模型及比例的选择对电网短路电流的影响。仿真分析结果对合理计算山东电网短路电流、优化电网网架结构具有指导意义。     

负荷动态实测参数与电网稳定计算

仿真计算了在暂态稳定问题中，负荷中感应电动机比例对极限切除时间的影响，并用负荷动态实测参数进行河南全网的稳定计算，与以往使用的近似负荷模型计算结果进行比较，结果表明，使用实测参数的河南电网商丘地区的电压稳定问题更加严重，而其他地区的稳定极限则由于实测负荷的电动机比例较小而有所提高。     

负荷模型对云南电网稳定性影响研究

分析了静态负荷模型与综合负荷模型对云南电网大理送出断面、德宏送出断面、云电外送断面输电极限计算的影响。结果表明,对于大理、德宏送出断面使用综合负荷模型计算的极限较静态负荷模型的高,而云电外送断面使用综合负荷模型计算的极限较静态负荷模型的低。因此,对于动态稳定计算而言,没有"保守"的负荷模型。     

马达负荷模型对华东电网暂态稳定性的影响分析

以华东电网为研究对象,采用中国电力科学研究院推荐的马达模型和参数,仿真比较了马达负荷模型的动态特性,分析了马达负荷模型对电网暂态稳定仿真结果的影响及原因,认为在电力系统暂态稳定仿真中,送端电网采用马达负荷模型有利于提高稳定水平。     

VSC-HVDC适应感应电动机负荷稳定性研究

日益增长电网负荷中心含有的感应电动机负荷,因其高度非线性和动态特性,给电力系统带来严重的电压失稳甚至崩溃的风险。文章通过研究感应电动机负荷特性,分析其与电力系统稳定的关联性。同时基于柔性直流系统功率传输可控特性,研究了一种柔直紧急支援控制策略,通过适当改变控制指令值调节交直流线路间的交换功率,从而实现负荷以及系统的稳定。最后通过PSCAD/EMTDC平台搭建某城市局部交直流系统模型,针对不同感应电动机负荷比例进行仿真分析。经验证,柔性直流系统采用该控制策略能有效提升电网感应电动机负荷稳定水平。     

A dynamic load model for analysis of power system voltage

It has become important in recent years that power systems be protected from voltage instability caused, in part, by heavy loads and the concentration of air conditioning loads during certain hours. Many studies have explored the problems and possible countermeasures. However, the load representations used in these studies are based on power values, i.e., P and Q; therefore, these analytic models are insufficient to express load responses and, thus, investigation is somewhat limited. This paper introduces a load model expressing load admittance responses by a first-order delay differential equation and uses this model in tandem with power network solutions to analyze power system voltage stability. This load model is shown to work reliably and effectively. Using this model, it is possible to investigate more precisely and widely than before the power system voltage stability phenomenon of arbitrary characteristic loads in lower voltage ranges and on propagations of instability through the networks.     

Algorithm for power system dynamic stability studies taking account of the variation of load power

This paper presents a probabilistic algorithm for determining the effect of initial state variation on the dynamic stability of power systems. Variation of operating conditions due to the uncertainties in load and generation is represented by the statistical attributes of nodal voltages. Expectation and covariance are employed to describe the distribution nature of random variables. The expected coefficient matrix in the state space equation is corrected by the second-order covariances. The solution gives the probabilistic distributions and conditional probabilities of eigenvalues. The proposed algorithm is examined on a two test systems.     

Modeling of a large electric power system for optimal control of dynamic stability

This paper describes a general state-variable form of mathematical modeling which may be used to control the dynamic stability of a larger power system optimally. Based on the linearization about the operating point of the system, a complete model for dynamic stability control is obtained by combining transmission network equations, full-order synchronous machine equations, the exciter and voltage regulator model, torque equations, and the governor-hydraulic model in a matrix form which includes supplementary excitation and governor control signals. The complete model may then be simplified as a low-order model by neglecting the governor effects, exciter time constant, and all but the field flux linkage variations of the machines in order to reduce computational requirements.     

浅谈电力负荷管理系统在用电营销管理中的应用

论述了电力负荷管理系统的功能及如何利用电力负荷管理系统来实现用户侧的数据采集、实时负荷监控等.     

Transient stability considering dynamic load in bulk power system with high DG penetration

Transient stability may be seriously affected when a large number of distributed generators (DG) stop simultaneously during voltage sag. It is necessary to analyze accurately the dynamics of bulk power systems with high DG penetration. In this paper, transient stability is studied by analyzing power‐angle curves of generators while considering load dynamics and model order reduction at lower voltages. Based on the analysis, a decrease in the load internal resistance after voltage sag causes transient instability of generators. The phenomenon is confirmed through simulation using a one‐machine and one‐load model. This paper also suggests that the simulation results might be misled by traditional bulk power system modeling such as using the static load model and ignoring impedance at lower voltages. As for the numerical simulation, a large level of DG stoppage leads to transient step out in a bulk power system, and the stability is greatly improved by DG voltage regulation. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 20– 29, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20608     

电力系统负荷预测方式综述

摘电力系统负荷预测方式可分为超短期负荷预测、短期和中长期负荷预测。给出了预测原始数据采集处理、模型简介,以及预测结果的处理。     

A mathematical model of an electric power system for dynamic state estimation

In this paper the derivation of a mathematical model of power system state-time behaviour is treated. A power system under normal operating conditions is considered. The mathematical model of the system state behaviour is expressed in terms of the state transition matrix. This model enables future system states to be predicted. The Kalman filter is utilized for the power system dynamic state estimation. A brief summary of representative test results is given.