A Real Application of Measurement-Based Load Modeling in Large-Scale Power Grids and its Validation

Load model is one of the most important elements in power system simulation and control. Based on more than 20 years of practice using load characteristic recorders in the measurement-based load modeling, this paper proposes the expectation composite load model to predict unseen data. The methods for load bus classification and parameter identification are also provided. The generalization capability of the proposed load modeling is validated by the measured load dynamics and system dynamics during two three-phase short circuit tests of the NE power grid in China. In order to evaluate the measurement-based load model, the probabilistic collocation method (PCM) is applied to quantitatively analyze uncertainties of the simulation responses raised by the parameters.     

Frequency-duration analysis of composite distribution system using a non-sequential Monte Carlo simulation

This paper presents a methodology for composite distribution system well being analysis based on non-sequential Monte Carlo simulation technique accounting uncertainties in capacity of distribution substation and distributed generation (DG). The method is based on a system state transition sampling approach which is used to calculate frequency and duration indices along with probabilities in healthy state, marginal state and risky state for a composite distribution system. Capacity of distribution substation and distributed generations are considered as normally distributed i.e. continuous capacity. The effectiveness of the method for evaluation of annual well being indices is demonstrated for a sample test system with DG capacity variation considering a seven step load model based on annual load duration curve. A comparative study is carried out which illustrates the effect of distributed generation capacity on well being indices of a distribution system.     

Composite system well-being evaluation based on non-sequential Monte Carlo simulation

The reliability evaluation of composite power systems has historically been assessed using deterministic and probabilistic criteria and methods. The well-being approach was recently proposed in order to combine deterministic criteria with probabilistic methods and evaluates the system by healthy, marginal and risky states. This paper presents an efficient method for composite system well-being evaluation based on non-sequential Monte Carlo simulation. It is assumed that the system is coherent, and the frequency and duration indices are calculated by the conditional probability method. The system adequacy is evaluated by a non-linear power flow solved by the Newton–Raphson method and by an optimal power flow solved by the Interior Points method. Results are presented for the IEEE-RTS system with a constant load and with a variable load curve. It is demonstrated that the proposed method, as well as the assumed hypothesis, are valid and provide an efficient alternative for the well-being analysis of large scale power systems.     

时序负荷曲线下电力系统概率性生产模拟

通过可用容量概率密度分布函数曲线与时序负荷曲线相结合，本文提出了一种基于时序负荷曲线的电力系统概论性生产模拟的新方法，它克服了传统方法不能考虑与时间相关的约束条件的弱点，并为加速水电优化和互联电力系统生产模拟提供了新路。应用情况表明：本文提出的方法对评估我国电网的电源结构有着十分重要的意义。     

面向多级电网调度运行的多业务培训仿真系统 (一)系统设计与实现

设计并搭建了一种融合调控专业多业务的全过程培训仿真系统,该系统可模拟培训过程中负荷曲线动态变化过程,且实现调度多业务协同培训仿真。通过获取生产系统真实数据及多业务协同运行,使得该培训仿真系统更为逼真地模拟电力系统调度运行环境。从系统的软硬件架构、负荷教案制作、多业务协同仿真等方面进行了阐述。所介绍的培训仿真系统已在实际电网调度中心得到应用,该系统的仿真数据与实际电网运行数据吻合,有效地支撑了电网调度运行人员培训和仿真工作需要。     

广东电网基于BPA的实用负荷模型的建立与校验

在实际工程应用中,根据经验得到的静态模型或者固定负荷比例的综合模型已经不能满足各区域大电网的要求,文中提出了一种能够很好与BPA结合的实用负荷模型,采用了基于非对称故障的方法进行建模,用小生境免疫算法对模型进行优化辨识,并用仿真实例进行了验证与校核。最后将该模型应用于广东电网的建模研究中。仿真表明该实用负荷模型的不仅能与BPA结合,也解决了数据来源的问题,同时精度高、实用性强。     

应用随机生产模拟制定联网互供电价初探

本在随机生产模拟理论的基础上结合边际成本的概念，采用均分联网节约效益的思想，初步探讨了互联电力系统交换电量的电价核算方法及原则。本还用削峰运行和引进电量分配因子，使水电模拟更为准确。本的核心是应用全解析的随机生产根据理论计算各类机组的详细出力过程。     

Effective techniques for reliability worth assessment in compositepower system networks using Monte Carlo simulation

Reliability cost/reliability worth assessment plays an important role in electric power system planning and operation. The paper proposes a technique for evaluating the costs of interruption and hence, the reliability worth in a composite power system network with time varying loads at load buses using sequential Monte Carlo simulation. A generalized methodology of determining the interruption costs, without considering the time varying aspect of the loads is discussed and the results are compared with those obtained by utilizing a load duration curve to represent the time dependent loads. Case studies conducted on the IEEE Reliability Test System (IEEE-RTS) are presented and discussed     

面向对象的电网仿真程序中负荷模型扩展方法

简要介绍了面向对象的新型电力系统仿真计算软件InterPSS的设计思想、系统结构及其自定义功能扩展的特点和基本思路;以三阶感应电动机并联恒阻抗综合负荷模型为应用实例,系统地阐述了InterPSS仿真计算软件中负荷模型的扩展方法并描述了其实现过程;采用Java语言编写了综合负荷模型的扩展程序并实现了与InterPSS之暂态稳定仿真程序的接口;通过对2机5节点系统的暂态稳定仿真检验表明扩展方法和实现过程正确.研究说明InterPSS自定义扩展功能强大,扩展方法简便灵活.     

牵引供电系统综合负荷实测建模

针对实测建模中牵引负荷时变性的问题,采用负荷特性分类及综合方法进行了一定程度的解决;通过研究牵引供电系统的结构原理,提出了一种改进型牵引供电系统综合负荷模型,运用总体测辨法对各个聚类中心等效样本进行参数辨识,给出了牵引负荷几种典型工况的推荐参数,为牵引负荷实测模型应用于电力系统仿真提供了基础.算例结果表明,改进型模型对负荷特性具有满意的描述能力,同时也验证了负荷特性分类及综合方法的有效性和合理性.     

The effect of load models on unstable low-frequency oscillationdamping in Taipower system experience w/wo power system stabilizers

This paper uses the eigenvalue analysis approach to observe the impact of load models on an unstable low frequency oscillation damping, which recently occurred in the Taiwan power system. In order to enhance oscillation damping, the effect of load models on power system stabilizers is also investigated. Three kinds of the derived load models (a dynamic model, a composite model, and an exponential model) based on the component approach with the measured characteristics of power system loads are used in this paper. Time simulation results are extensively used to verify the eigenvalue analysis results with and without power system stabilizers. One set of field test data obtained from the Taiwan power nuclear plant with power system stabilizers is used to determine which load model provides a more accurate result in enhancement of oscillation damping. Depending on the results, the effect of load models on electromechanical oscillation damping with and without power system stabilizers is verified     

电力系统综合负荷模型简化方案及辨识参数集选取

负荷是电力系统的重要组成部分,建立合理的负荷模型对电力系统安全稳定分析和实时监控具有重要意义。目前综合负荷模型被广泛采用,但完整描述其动态特性需要十余个参数,在线辨识全部参数几乎不可能。文中从综合负荷模型状态方程入手,在保证暂态响应近似相等的准则下提出一种综合负荷模型简化方法,并在此基础上分析不同的参数对负荷动态特性的影响以及参数之间的相关关系,最终选取了感应电动机比例、电动机暂态电抗、电动机稳态滑差以及电动机转子时间常数组成辨识参数集,并通过仿真验证了相关结论。     

电动汽车参与电网调峰的分析研究

将电动汽车作为可移动储能元件并入电网,进行统一的管理和调度,在电网负荷低谷期充电,在负荷高峰期进行放电,可对电网进行调峰,拉平负荷曲线。提出一种电动汽车与电网互联V2G模型,及其参与电网调峰的分析模型,以分析电动汽车参与电网调峰的效果。该模型通过将每天的负荷曲线分段,按照电动汽车的所存储的能量和负荷曲线,采用粒子群寻优算法对其充放电时间进行优化计算。通过仿真实验分析,本文所提出的控制模型对电网调峰分析有良好的效果,可用于将来电动汽车并网控制的分析。     

积分流形模型化简方法在动态电压分析中的应用

利用积分流形模型化简(IMMD)的思想,给出了含动态电压调节器(DVR)配电网络的动态电压分析方法.文中建立了包括DVR在内的线路、有载调压变压器、负荷等相关设备的数学模型,指出了系统的多时标特性.利用积分流型将快过程等效并入慢过程.通过计算实例,表明了这一方法能够在保证分析精度的前提下大大提高仿真效率.     

Reducing Identified Parameters of Measurement-Based Composite Load Model

A load model is one of the most important elements in power system simulation and control. Recently, the constant impedance, constant current, and constant power load in combination with the induction motor load have been widely used as the composite load model, whose parameters are all identified from the field measurements in measurement-based load modeling practices so far. However, there is virtually no research conducted on whether all these parameters could really be identified. This paper investigates the possibility on reducing the number of composite load model parameters to be identified from field measurements. This paper first shows that direct application of the IEEE load motor parameters in the composite load model may be inadequate on describing the load dynamics over different operating status. Then the perturbation method is used to derive the trajectory sensitivities of the equivalent motor parameters, based on which the reduction on the identified parameters of the composite load model is presented. Two cases of measurement-based load modeling in North China and Northeast China are studied to illustrate the validity of the reduction method. It is shown that the reduction does not lose the model's capability on describing the load dynamics. The reduction on the number of identified parameters not only provides a possible way to solve the multi-valued load model problem based on the current practices on measurement-based load modeling, but it also facilitates building of the load model with more components included in it. Meanwhile, reducing the identified parameters reduces the identification time; thus, the proposed strategy significantly enhances the efficiency of the load modeling work.     

配网侧接入电源对负荷建模的影响

研究了配网侧接入电源对负荷建模的影响.发现当配网侧电源的发电容量逐渐增大时,原有的感应电动机并联恒阻抗、恒电流、恒功率(ZIP)模型的负荷模型将不再能很好地反映该区域的负荷特性,进而提出了一种新的负荷模型结构--异步发电机并联ZIP模型.通过仿真计算,验证了该新负荷模型的有效性,并进一步统一了上述2种负荷模型,称为异步机并联ZIP负荷模型.     

多微网配电系统协调优化调度和经济运行研究

多微网系统由多个子微网构成,其控制策略较单微网系统更为复杂,针对多微网系统,提出了一种基于预测控制的多微网协调控制策略,根据微网的动态出力范围,考虑网损和负荷波动方差构建多目标优化函数,通过预测控制求得多微网协调因子的最优值,基于此最优值协调各微网之间的功率分配,从而维持整个微网电压和频率的稳定,并运用基于随机模拟的粒子群算法求解上层优化问题。仿真结果显示:基于多微网与电网合理的调度,可充分发挥微网"荷-源"双重特性的灵活调度,平滑负荷曲线并降低系统网损并可减轻负荷波动对电网影响以及可再生能源出力的不确定性。     

基于Johnson分布体系的含风电场发电系统可靠性评估

提出了一种基于Johnson分布体系的多维变量建模方法,并将其应用于含风电场发电系统年度可靠性指标计算中。该方法利用风速历史数据和持续负荷曲线构建风速和负荷与标准正态变量的关系,即模拟风速和负荷的概率分布特征,进而通过模拟相关多维标准正态变量来实现对风速相关性的模拟,避免了因假设风速概率分布模型可能导致模拟精度低的缺点。通过算例分析,验证了算法在模拟负荷和风速分布时的精度以及应用于含风电场发电系统可靠性评估中的适用性。在此基础上分析了风电场风速相关性对含风电场发电系统可靠性指标的影响。     

基于粗糙集理论和动态时序模型的日负荷曲线预测新方法

作者提出了一种短期日负荷曲线预测新方法.该方法首先采用日最小负荷对日负荷曲线进行规范化,再将日负荷曲线预测转化为对日最小负荷的预测和对日规范化负荷曲线的预测.对日最小负荷预测应用动态时序模型;对日规范负荷曲线应用专家系统进行推理预测,专家系统中的推理规则应用粗糙集理论从历史数据中获取.采用上海电网数据对该预测方法进行了测试,结果表明该方法便于对各种影响因素进行分析处理,能够更有效地利用历史数据所包含的信息.     

基于负荷特性分析的中长期负荷预测主导因素辨识法

对于电力系统而言,精确的负荷特性分析有助于准确地把握负荷曲线的变化规律,提高预测结果的精度。根据地区电网历史负荷数据和相关资料,深入分析了各负荷特性指标与影响因素的关联性,提出了基于负荷特性分析的中长期负荷预测主导因素辨识法。采用Pearson相关分析的基本原理,该方法能有效挖掘出真正对负荷曲线形状产生影响的因素,并结合偏最小二乘回归法应用于负荷预测建模。通过算例对比分析,验证了此方法实用、有效。