A simulation model for reliability evaluation of space stationpower systems

The dependence of reliability and storage characteristics during Sun and eclipse periods is considered. The charging and discharging of energy storage modules is included on a continuous basis. Sample system studies are also presented. The Monte Carlo analysis program for reliability analysis of a hybrid configuration can model the charging and discharging of energy storage devices in a more realistic manner than the approach of C. Singh et al. (1987). The results shown do not indicate any significant effect on computed reliability indices by this more refined modelling of charge/discharge of energy storage     

输电系统风险评估中的分层分级负荷削减模型

负荷削减计算是输电系统风险评估中的关键步骤.为解决目前负荷削减模型还存在的没有考虑无功潮流和节点电压约束、无法考虑负荷类型削减优先级对风险指标的影响等不足,提出了一种分层分级最优负荷削减模型.按负荷类型重要度从高到低依次分层削减负荷,兼顾就近和最优原则,将参与负荷削减的节点限制在一定分级范围内,减小计算规模.IEEE-...     

基于二分法的聚类负荷模型及其在电力系统可靠性评估中的应用

目前用于可靠性评估的负荷模型主要有峰荷模型、分级负荷模型以及聚类负荷模型等,这些模型难以同时满足计算精度和计算复杂性的要求.建立了基于二分法的聚类负荷模型并将其应用到电力系统可靠性评估中.该模型利用二分法原理较快地确定最佳分级数,利用快速排序算法和聚类技术将年负荷曲线中各负荷点归并到相应的负荷级,具有降低计算复杂性和提高模拟精度的特点,能较好地反映负荷实际变化趋势.应用该模型对IEEE-RTS79测试系统进行可靠性评估,通过比较几种不同负荷模型下的可靠性评估结果,说明所提模型准确可靠,计算量较小,具有应用价值.     

基于二分法的聚类负荷模型及其在电力系统可靠性评估中的应用

目前用于可靠性评估的负荷模型主要有峰荷模型、分级负荷模型以及聚类负荷模型等,这些模型难以同时满足计算精度和计算复杂性的要求.建立了基于二分法的聚类负荷模型并将其应用到电力系统可靠性评估中.该模型利用二分法原理较快地确定最佳分级数,利用快速排序算法和聚类技术将年负荷曲线中各负荷点归并到相应的负荷级,具有降低计算复杂性和提...     

一种新的广义电力负荷模型及其工程应用

当区域负荷中含有较高比例的电源时,传统的经典负荷模型不适合描述负荷母线的动态行为.提出一种新的广义电力负荷模型,并给出模型参数的确定方法.该方法综合利用常规量测数据和PMU量测数据,其中等值发电机支路参数采用理论等值方法获得,而纯负荷参数采用辨识方法获取.实际工程应用表明,该广义电力负荷模型及其参数确定方法有效可行.     

基于Gauss-Markov模型的电力系统t型抗差状态估计

将t型估计引入状态估计中,提出自适应Gauss-Markov模型的t型抗差状态估计。该方法能够克服传统不良数据辨识程序不能很好地辨识多个强相关不良数据的不足,且与传统状态估计程序具有很好的兼容性,利用t分布的自由度动态调节估计的效率和抗差性。该方法目标函数连续可微,可利用与加权最小二乘(WLS)法类似的牛顿法进行求解。IEEE标准系统和某实际输电网测试验证了所提方法的有效性,与含不良数据辨识功能的WLS估计和二次-常数(QC)估计相比,所提方法的抗差性具有明显的优势。     

考虑供电公司风险的激励性可中断负荷合同模型

考虑到供电公司的风险偏好及用户的可中断电量,应用委托代理及机制设计理论建立了一种用户类型离散的可中断负荷合同模型。分析和算例结果表明,无论供电公司的风险偏好如何,该合同模型均能引导用户披露真实信息,实现电力资源的有效配置,且供电公司能从中节约供电成本。因此,激励性可中断负荷合同不仅能提高用户需求弹性．还有助于供电公司回避市场风险。     

投影梯度法模糊层次综合评价模型在饱和负荷分析中的应用

提出了基于投影梯度法的模糊层次综合评价模型,对城市饱和负荷水平进行客观评价。根据评价指标体系,创建了判断矩阵和一致性指标函数。利用投影梯度法计算一致性指标函数最小值,检验、修正判断矩阵的一致性。通过调整判断矩阵的各评价因素标度改进了一致性指标值,优化了各评价因素的权重。计算结果表明:此算法是一类"主动"方法,计算权值误差小,计算稳定性强,克服了权重计算时主观性较强的缺陷,提高了评价结果的合理性。同时,以某市电网为研究对象,从社会因素、自然因素、经济因素3个方面,评价了该市负荷饱和水平,评价结果合理有效,具有良好的参考作用。     

A stochastic load model for an electricity market

This paper presents a stochastic load model that uses a regression equation coupled with a time series model. The model is simple but without compromising accuracy. A 24-h set of regression equations incorporates the hourly temperature variations. Weekly seasonality is handled by providing weekday and weekend non-linear regression equations. The Levenberg–Marquard method is used because of its superiority over the widely used Gauss–Newton and steepest descent methods in estimating model parameters and to avoid “slow down” in the search process, respectively. A residual discrete time series is determined by using the autoregressive integrated moving average (ARIMA) model. Test results using PJM-market load data indicate the effectiveness of the proposed model to predict the daily electricity load.     

变压器有载合闸的非线性数学模型及仿真

已提出的变压器有载合闸模型,都是将时变的励磁电感进行线性化或分段线性化处理,这种处理方式不能光滑地反映铁芯的非线性特征,造成仿真误差。建立了一个比较合理且精确的变压器有载合闸的非线性数学模型,铁芯的励磁特性采用了多值磁滞特性。根据该模型建立各支路电流的状态方程,并通过数字实时仿真证明了目前各种采用涌流特征进行闭锁的变压器差动保护经历带负载合闸时,尤其是在外部故障切除后电压恢复过程中受超饱和现象的影响,存在误动的可能性,指出应规定不推荐进行变压器有载合闸。进一步验证了变压器差动保护原理的局限性。     

灰色模型在电力负荷预测中的应用与改进

灰色GM(1,1)模型是一种较有效的负荷预测模型,然而由于电力负荷具有多样性,当负荷增长曲线不是G型时,其预测误差较大,精度不能满足要求,在实际应用中具有一定的局限性。对灰色GM(1,1)模型进行必要的改进,通过实例分析,利用等维新息递推模型、组合灰色模型进行负荷预测,可大大提高预测精度。     

A model for predicting motor load for an armored face-conveyordrive

A formula for calculating the power requirements of an armored face conveyor (e.g. for coal mining applications) is presented. Techniques to determine the conveyor speed-torque curve and to estimate the acceleration time for a loaded conveyor are also given. Using this information, an algorithm to estimate the maximum length for a face conveyor is developed. An application of the algorithm to power system analysis is presented. By using the developed algorithm, the performance as well as the maximum length of a longwall face conveyor can be readily evaluated     

电力负荷预测的最优分段校正模型研究及应用

中长期电力负荷同时具有增长性和波动转折性的二重趋势，这使得电力负荷的变化呈现出复杂的非线性特征。传统的中长期负荷预测模型仅考虑一种变化趋势，从而预测效果较差，不能符合实际需要。为了提高预测精度，更精确地反映负荷变化规律，通过改变GM(1，1)模型中微分方程的初始条件，且对历史负荷进行最优分段，在此基础上建立了电力负荷预测的最优分段校正模型，使模型具有二重趋势性特点。通过实例验证，较大提高了预测精度。     

A class of models for load management application and evaluationrevisited

The problem of load modeling for demand side management (DSM) purposes is addressed. The proposed load models rely on information about both the physical characteristics of elemental load devices at the distribution level and usage statistics of these devices. Although the class of models discussed has been previously proposed in the literature, its suitability for DSM purposes is definitely established by showing how the models can be a tool for real DSM actions evaluation. Some results are shown     

水文水力学模型及其在洪水风险分析中的应用

流域洪水模拟是当前洪水计算分析的热点,也是防洪减灾工作的科学依据和指导。本研究通过将分布式水文模型和水动力学模型串联耦合的方法计算流域洪水淹没过程,以重庆龙溪河流域作为研究区域,基于SWAT和HEC-RAS模拟平台,综合考虑气象资料、地形、下垫面条件等,经产汇流计算、小流域洪水二维数值模拟等过程得到小流域在不同情境（暴雨重现期）下的二维淹没情况。以当地洪水计算手册推求洪水过程作为验证,模型计算结果显示模型能够较好模拟龙溪河流域复杂条件下的汇流过程,结合灾害损失评估和洪水风险分析,为当地减灾工作提供决策支持。     

负荷模型简化辨识及在河南电网的仿真应用

使用相量测量单元（PMU）的实测数据,进行了大量的感应电动机负荷模型参数灵敏度分析,并从参数灵敏度的角度出发,提出了将灵敏度较小的感应电动机负荷模型参数固定,仅辨识灵敏度较大参数的方法。结合电网实际扰动仿真、暂态故障曲线Prony分析以及电网小扰动分析,使用综稳程序PSASP进行仿真分析,仿真结果证明了所提简化模型辨识的可行性和实用性。     

基于TCN-GRU模型的短期负荷预测方法

为了进一步提高短期负荷的预测精度,为电力系统的稳定运行提供更加有力的保障,文中提出了一种将时间卷积网络(TCN)和门限循环单元(GRU)相结合的短期负荷预测方法TCN-GRU。首先,将采集的训练数据划分为时序数据和非时序数据;其次,将时序数据输入到TCN模型中以提取时序特征;然后,将提取出来的时序特征与非时序数据组合起来输入到GRU模型中对模型进行训练;最后,利用训练好的模型实现对短期电力负荷的预测。基于广东省佛山市某行业真实负荷数据验证了TCN-GRU模型的负荷预测能力,并通过对比多种深度学习模型的预测效果,验证该模型具有更高精度的短期负荷预测能力。     

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.     

A unified three-phase transformer model for distribution load flow calculations

This paper provides a unified method to model three-phase transformers for distribution system load flow calculations, especially when the matrix singularity caused by the transformer configuration arises. This paper shows that the singularity appears only in certain transformer admittance submatrices and only in certain transformer configurations. The unified method presented in this paper can solve the voltage/current equations in the forward/backward sweep algorithm for various types of transformer configurations, whether or not the corresponding admittance submatrices are singular. Comprehensive comparisons have been made between the proposed approach and other methods. Test results demonstrate the validity and effectiveness of the proposed method.     

A physically based diode model for circuit simulation

A physically based power PiN diode model is presented. Eigen value internal approximation method is used to solve the ambipolar diffusion equation. This model is implemented in SIMPLORER circuit simulator using VHDL‐AMS language. The proposed model can be used in both circuit simulators and the optimization of a given power PiN diode. Good agreement is obtained by comparing the results of the suggested model with experimental data. Copyright © 2013 John Wiley & Sons, Ltd.