结构约束特性同步发电机及励磁系统动态参数聚合方法

针对动态等值中发电机及其励磁系统的聚合问题,提出一种解析聚合方法。该方法精确考虑了母线化简时将等值机移至公共母线时电压角度的变化。发电机及其励磁系统的等值参数通过非迭代的解析推导能够直接求取。基于发电机励磁系统模型状态空间系数矩阵的结构约束特性,本文实现了模型不同的励磁系统的动态聚合。与传统基于传递函数拟合和时域仿真的聚合方法相比较,本文方法对含不同发电机及其励磁系统模型复杂大电网的动态聚合问题有更强的适应性。     

电力系统动态等值中原动机调速系统聚合的研究

动态等值中进行原动机调速系统聚合时,如果各模型不相同,采用加权求和法所得聚合模型阶次很高。为此,提出采用统一的标准传递函数作为等值原动机调速系统模型的结构,采用频域最小二乘法获得等值原动机调速系统模型的参数。这种方法可以适应各种原动机调速系统,而且聚合后的应用也很方便。仿真算例结果表明,采用适当阶次的标准传递函数作为等值模型,聚合前后原动机调速系统的特性非常接近,由此验证了模型和方法的有效性和适用性。     

电力系统动态等值中原动机调速系统聚合的研究

动态等值中进行原动机调速系统聚合时,如果各模型不相同,采用加权求和法所得聚合模型阶次很高.为此,提出采用统一的标准传递函数作为等值原动机调速系统模型的结构,采用频域最小二乘法获得等值原动机调速系统模型的参数.这种方法可以适应各种原动机调速系统,而且聚合后的应用也很方便.仿真算例结果表明,采用适当阶次的标准传递函数作为等值模型,聚合前后原动机调速系统的特性非常接近,由此验证了模型和方法的有效性和适用性.     

舰船电力系统发电单元时域聚合方法

根据现有等值方法,提出了一种改进的、适合舰船电力系统特点的在线动态等值方法。该等值方法在对发电单元进行聚合时,发电机、励磁系统、调速器都保留原有模型结构。根据舰船电力系统特点,发电机采用考虑次暂态的六阶模型,给出了基于六阶发电机模型的参数计算公式和聚合的一般步骤。在计算等值模型的参数时,采用了时域的非迭代代数运算,减少了运算时间。在对某一实际包含12台发电机的舰船电力系统进行建模等值时,应用该方法,给出了等值参数及在PSCAD/EMTDC仿真环境中的动态响应曲线。验证了该等值聚合方法的有效性。     

福建电网分区动态等值研究

对与华东电网互联的福建电力系统进行了基于同调等值法的分区等值,在等值过程中对系统线路参数和发电机参数进行了调整和聚合,得到了在网络拓扑结构不变条件下适用于不同运行方式的等值模型。该模型能够仿真系统的运行特性,并适用于RTDS建模和其它电力系统仿真软件的建模。     

基于BPA的省级电网实用动态等值方法

对省级电网的外部系统和内部系统动态等值方法进行了研究。省级电网外部系统动态等值中,基于我国省级电网间的弱交流联络特性,提出以短路电流不变、电压不变和省间联络线潮流不变为原则进行简化等值;省级电网内部系统动态等值中,为突破目前与BPA程序接口的电力系统动态等值程序(power system dynamic equivalent program,PSDEP)的局限性,以励磁系统参数聚合为例,对比分析了"动态等值预处理–PSDEP–模型转换"与"动态等值预处理与发电机参数聚合–PSDEP"两种技术路线,分析结果表明在动态等值精度要求高的情况下,有必要开发新的发电机参数聚合程序。该省级电网动态等值方法可加快动态等值工作,适应电力系统规划、运行部门的工程精度要求,实用性好。     

电力系统动态等值参数聚合的实用方法

在大规模电力系统暂态稳定分析中，为减少数值仿真的计算量，可采取动态等值的方法对系统进行简化。电力系统动态等值包括相关机群动态识别、网络化简和相关机群参数聚合3部分。针对第三部分提出了一种基于加权法的相关机群详细模型参数聚合的方法，该方法可用于获得等值发电机组及其调节系统的详细模型参数和负荷等值异步电动机的详细模型参数。这种方法既达到了参数聚合的目的，又减少了计算时间。对IEEE10机39节点系统和简单配电系统进行仿真，并与频域法相比较，结果表明了该等值方法的有效性。     

基于电网动态等值的PSS参数智能优化方法

针对电网静态等值方法无法反映发电机近端机组的影响,提出一种新的电网等值方法,将发电机以外的系统等值为一台二阶动态机组和无穷大母线的并联,根据发电机机端数据,采用电网静态等值方法和递推最小二乘法辨识动态等值系统的参数;采用三机系统的线性化Heffron-Philips模型求得励磁控制系统的无补偿相频特性;根据相位补偿原理采用模拟退火粒子群优化算法对电力系统稳定器(power system stabilizer,PSS)参数进行智能优化。仿真结果表明,优化后的PSS参数能够提供更多的阻尼,更好地抑制低频振荡。     

基于同调机群识别的动态等值方法的工程应用

在PSS/E环境下建立了大规模电力系统的动态等值模型,动态等值包括发电机同调机群的识别、同调机的聚合和网络化简.发电机同调机群的识别采用时域仿真方法,同调机的聚合采用经典模型,网络化简采用拓扑化简.以华东电网为例,阐述了等值系统的建立过程,并对等值系统和原型系统进行了仿真分析和比较,仿真结果表明,等值系统可以很好地再现原型系统的动态特性.     

基于改进遗传算法的非线性发电机励磁系统参数辨识

为了确保电力系统建模的精确性和安全稳定分析的可靠性,进行发电机励磁系统参数辨识测试是一项重要的工作。提出采用改进的GA遗传算法应用于发电机励磁系统的非线性参数辨识,利用GA较强的全局寻优能力和BP梯度法较强的局部搜索能力,较快同时又较好地辨识出发电机励磁系统参数估计值。实际发电机励磁系统参数测试试验结果表明,基于改进遗传算法的励磁系统参数辨识方法计算速度快,精度高,鲁棒性强,为非线性发电机励磁系统的参数辨识提供了一种有效的新方法。     

Aggregation of exciter models for constructing power system dynamicequivalents

Constructing a dynamic equivalent for a power system involves several steps: the partition of the system into coherent areas, the coherent area aggregation, and the aggregation of the coherent generators and their control devices. In this paper we investigate the aggregation of exciter models. A trajectory sensitivity method is used to tune the aggregate exciter parameters of the reduced model. The optimal results are used to evaluate the aggregation from the DYNRED program and a weighted MVA method. A three-machine system with one coherent area satisfying the theoretical coherency conditions is used to investigate the impact of the variations of the individual generator, network, and exciter parameters on the aggregate exciter model parameters. The results are then applied to the exciter aggregation of a larger 48-machine system     

Coherency and model reduction: state space point of view

Analytical connections are determined that relate coherent stability behavior of generators to redundancy in the controllability and observability gramians of the linear model of the power system. This redundancy is removed from the gramians of the reduced-order model generated by aggregating the coherent machines. Model reduction in large power systems is shown to be better if the order estimation information in the controllability and observability gramians is weighted properly by balancing the system. Perfect coherency of generators is related to the parameters of the linear model of the power system. Waveforms for generating the RMS coherency measures are compared. An algorithm for order reduction based on balancing is outlined and justified by testing on a 240-generator, 2500-bus system     

Identification of coherent generators considering the electrical proximity for drastic dynamic equivalents

This paper describes an application of the coherency-based dynamic equivalent methodology to determine drastic reductions in the representation of power systems. This condition is necessary for real time power system simulator studies. The paper demonstrates that the exclusion of electrically distant generators from the coherent groups solves the convergence problems that may appear in the power flow algorithm during the calculation of drastic dynamic equivalents. This paper also demonstrates that for each fault neither the strongly coherent generators are always electrically close, nor the approximately coherent generators are always electrically distant. The New England system and two simplified configurations of the Brazilian interconnected power system are considered in the studies.     

Application of coherency and reduced order models to transient stability studies

Study of the transient stability of a large and interconnected power system requires a great deal of computational time. To reduce that time, power system equivalents are employed. A simplified transient stability method, based on the values of the ‘stability measures’, is presented in which generators with small swing are replaced by a new equivalent model, and appropriate simplified models are used for the rest of the generators. Results of this study are used to identify coherent groups of generators. Replacing coherent sets by their equivalent generators will further reduce the size of the system. The validity and accuracy of the method is demonstrated by stimulated tests on a sample power system.     

A new approach for online coherency identification in power systems based on correlation characteristics of generators rotor oscillations

In this paper, a new approach for identifying coherent groups of generators in power systems based on the correlation coefficients between rotor angle/speed oscillations of generators is presented. The method uses a newly proposed clustering index based on the correlation coefficients of generators oscillations which is able to classify any number of generators into coherent groups. The proposed approach uses real time data of generators oscillations via VAMS/PMUs, so it is able to easily take into account the effect of system detailed modeling, generators and system controllers and type of events. The proposed correlation index evaluated from the real time behavior of generators in time-domain following disturbances are used to evaluate the degree of coherency between any pair of generators. The generators’ rotor angles and speeds can be obtained from synchronized measurements of system quantities using PMUs. Hence, the proposed method could be integrated into a wide-area measurement system enabling fast identification of coherent groups of generators. It is shown that by using COI of the aggregated in-phase coherent groups, the frequency of the inter-area mode can be evaluated. The proposed method is tested on the IEEE 39-bus with 10 generators and realistic power system of Iran with 405 generators.     

PSS2A模型的反调现象分析

根据PSS2A的理论模型推导,采用加速功率作为输入信号的电力系统稳定器不出现反调,但实际机组励磁系统中配置的PSS2A模型输入量角速度并不是实际的发电机角速度,而是通过矢量变换和等效计算得到的等效发电机角速度,因此,实际机组的PSS2A模型必然存在一些反调现象.结合广东台山电厂4号机组的无功功率异常波动问题,通过BPA...     

Representation of coherency-based equivalents in transient stability studies

An equivalent generator model designed to replace a group of coherent generators is discussed. The equivalent generator incorporates the equation of one of the generators in the corresponding coherent group. Any degree of detail is possible in the model representation of the group.Application of the coherency-based equivalent to reduce the size of a given power network is demonstrated in the paper, and results are presented which indicate the performance of the reduced-order model.     

区域互联电力系统同调机群的分布式协同识别

在电力市场条件下,区域子系统运行具有相对的独立性、系统数据具有一定的不透明性.文章研究了与市场条件相适应的区域互联电力系统的同调发电机识别问题,基于弱耦合算法提出了一种子系统内同调机群的分布式识别方法,在相邻区域子系统间通过交换少量的边界母线信息可形成子系统状态矩阵,实现对子系统内同调机群的识别.通过50机145节点系统的算例验证了该方法的有效性.     

用支路分割区域迭代法作同调机群协同识别

动态等值是提高复杂大型互联系统动态行为分析速度的一种有效方法。在电力市场条件下,区域子系统运行具有相对独立性,系统数据具有一定的不透明性。本文研究了与市场条件相适应的区域互联电力系统发电机同调识别问题,基于经典的时域仿真算法,提出了一种子系统同调机群分布式识别方法。在支路分割的系统分裂下,邻接区域子系统间通过交换少量边界母线信息,完成区域迭代,实现对子系统同调机群识别。通过10机39节点系统算例,验证了该方法的有效性。