负荷与PSS的相互作用对系统动态稳定的影响

1996年8月10日WSCC大系统事故重现过程中，负荷模型的改变起到了至关重要的作用，但是负荷起着决定性作用的原因却一直无从知晓，因此，文中应用电力系统中长期动态仿真软件Eurostag，仿真分析事故过程中负荷与电力系统稳定器（PSS）控制的相互作用对系统动态稳定的影响；采用时域仿真与小扰动分析方法，分析不同的负荷特性对系统阻尼及对PSS参数整定的影响；讨论了负荷与PSS相互作用的过程及其导致系统失稳的原因。仿真分析表明，如果WSCC系统仿真应用准确的负荷模型，PSS参数整定正确，系统可能不会轻易发生振荡。     

负荷模型对PSS参数整定的影响

文章推导了单机无穷大系统机端带负荷时系统的6个系数K1～K6、同步转矩系数和阻尼转矩系数。以云南某水电机组为例分析负荷模型对PSS电磁功率信号(-ΔPe)大小、相位和PSS参数整定的影响并通过3机9节点系统的小扰动稳定分析加以验证。通过分析表明,负荷模型对PSS时间常数和放大倍数的整定都有一定程度的影响,负荷与PSS相互作用在不同的情况下对系统稳定性的影响不同,因此,在分析负荷模型对电力系统稳定性的影响时,应考虑PSS的作用,同样,在进行PSS参数整定时,不可忽略机端负荷的影响。     

基于实测轨迹校正模型参数对电力系统频率动态过程仿真精度的影响

研究电力系统频率动态过程的重要手段是基于数值仿真的方法,但多次事故后仿真复现表明,采用现有的模型及参数无法准确描述实际电力系统的频率动态过程,仿真结果与实测轨迹之间存在明显偏差。文章首先基于WSCC系统,分析不同参数对频率动态过程的影响趋势,并基于东北电网网架结构和实测数据,在复杂多机系统中验证从WSCC系统得出的不同参数物理特性结论。基于实测轨迹并参考参数的物理特性结论校核频率动态过程仿真模型和参数,提高频率动态过程的仿真精度,对于整定低频减载方案,克服以往保守的运行方式等方面提供有效依据。     

宁夏电网电力系统稳定器PSS参数整定及其对系统稳定性的影响

基于宁夏电网大机组励磁系统实测模型,分析宁夏电网大扰动动态稳定问题特性,提出加强其动态阻尼的PSS整定原则.对网内主要机组进行了PSS参数整定试验,并以特定机组为例进行说明.仿真分析计算表明PSS参数整定后对宁夏电网系统大扰动动态稳定和小干扰动态稳定特性均有改善作用;并通过网内大机组甩负荷的大扰动试验证明了PSS整定的有效性.     

通过系统扰动试验进行安康水电厂3号发电机组PSS性能验证分析

随着电网建设规模越来越大，弱联系的大电网间呈现弱阻尼情况，在系统扰动时往往发生低频振荡，电力系统稳定控制PSS是提高系统阻尼，平息系统振荡的一个有效措施。针对安康水电厂3号机组PSS，通过安南Ⅱ线带负荷跳闸扰动试验，对比分析了PSS以理论计算参数整定和实测参数整定的作用效果，验证了PSS的实际性能和对系统稳定的影响。     

PSS参数误整定引起有功波动原因分析

随着电网供电区域不断扩大,电网结构日趋复杂,大型弱联系电网固有的自然阻尼有时会使电力系统之间发生有功低频振荡。通过发电机的菲利普斯-海佛容模型分析可知,在远距离、重负荷送电的情况下,加之快速励磁系统普遍应用,更是加剧了这一状况,为了改善新型电力系统动态安全稳定性影响,作为励磁系统的附加装置电力系统稳定器(PSS)发挥了高效且经济作用。目前应用广泛的双输入加速功率型电力系统稳定器PSS 2A,通过适当的环节参数整定,可以在特定的频段内对励磁系统滞后特性进行有效补偿,使励磁系统提供足够的正阻尼,使系统发生的低频振荡快速衰减。然而当PSS参数整定不合理,对励磁系统调节产生不正确的补偿,就有可能影响发电机稳定运行,严重情况下甚至会引发低频振荡。本文以发电机的Phillips-Haffron模型分析为基础,从发电机电磁转矩的角度分析,在Δδ-Δω坐标系中得到了励磁系统调节对发电机稳定性的影响。最后通过一起PSS参数误整定分析,验证了等效加速功率型PSS 2A模型仿真的正确性。     

基于增强连续禁忌算法的PSS参数优化

多机系统中,电力系统稳定器PSS(Power System Stabilizer)的参数配置是一个复杂的非线性优化问题。描述了电力系统模型、PSS模型及参数优化目标函数和约束条件。介绍了增强连续禁忌算法ECTS(Enhanced Continuous Tabu Search)的主要组成部分及算法流程图。并以WSCC3机9节点系统为例进行PSS参数优化,通过发电机在不同方式下(正常、负荷高峰、负荷低谷)的动态性能仿真,结果表明：用ECTS算法参数优化后的PSS动态性能优于常规方法设计的PSS,具有一定的鲁棒性。     

发电机励磁系统调差对PSS参数整定的影响与对策

介绍了发电机励磁系统调差的原理与作用,论述了电力系统稳定器(PSS)原理及其现场参数整定方法.针对自并励励磁的水电机组,将PSASP小干扰稳定仿真结果与现场测量数据进行对比,分析总结了不同调差系数引起的励磁系统无补偿频率特性偏移对PSS参数整定的影响,论证了PSS参数整定过程中必须考虑调差系数设置,提出采用小干扰稳定计算的方法来校验调差系数设置变化后对已投入运行的PSS功能的影响.     

宁夏电网电力系统稳定器投入及验证试验

基于宁夏电网大机组励磁系统实测模型,分析了电网动态稳定问题特性。提出了加强系统动态阻尼的PSS整定方案,完成了网内主要机组PSS参数整定试验。仿真计算表明,PSS投入后对系统动态稳定特性有较大改善。大扰动试验为PSS投运后阻尼效果提供了宝贵的系统试验数据,验证了该网PSS投入的有效性。     

基于Matlab的PSS的仿真分析

分析了低频振荡产生的原因以及电力系统稳定器（PSS）对低频振荡的抑制作用。利用Matlab对PSS的参数进行整定,并建立了励磁调节系统仿真模型。用3种运行方式验证电力系统稳定器抑制低频振荡的能力。仿真结果表明：整定后的电力系统稳定器对低频振荡具有良好的抑制作用。     

Effects of various power system stabilizers on improving power system dynamic performance

To ensure the small-signal stability of a power system, power system stabilizers (PSSs) are extensively applied for damping low frequency power oscillations through modulating the excitation supplied to synchronous machines, and increasing interest has been focused on developing different PSS schemes to tackle the threat of damping oscillations to power system stability. This paper examines four different PSS models and investigates their performances on damping power system dynamics using both small-signal eigenvalue analysis and large-signal dynamic simulations. The four kinds of PSSs examined include the Conventional PSS (CPSS), Single Neuron based PSS (SNPSS), Adaptive PSS (APSS) and Multi-band PSS (MBPSS). A steep descent parameter optimization algorithm is employed to seek the optimal PSS design parameters. To evaluate the effects of these PSSs on improving power system dynamic behaviors, case studies are carried out on an 8-unit 24-bus power system through both small-signal eigenvalue analysis and large-signal time-domain simulations.     

Tuning of power system stabilizers using genetic algorithms

Several techniques exist for developing optimal controllers. This paper investigates the tuning of power system stabilizers (PSS) using genetic algorithms (GA). A digital simulation of a linearized model of a single-machine infinite bus power system at some operating point is used in conjunction with the genetic algorithm optimization process. The integral of the square of the error and the time-multiplied absolute value of the error performance indices are considered in the search for the optimal PSS parameters. In order to have good damping characteristics over a wide range of operating conditions, the PSS parameters are optimized off-line for a selected set of grid points in the real power (P)-reactive power (Q) domain. The optimal settings thus obtained can then be stored and retrieved on-line to update the PSS parameters based on measurements of the generator real and reactive power. Time domain simulations of the system with GA-tuned PSS show the improved dynamic performance under widely varying load conditions.     

基于多参数分岔分析方法的多机系统动态负荷裕度研究

采用多参数分岔分析方法对多机系统的动态负荷裕度进行研究,比较了基于连续潮流的分析结果和准静态分析结果的差别;以励磁参考电压Vref为控制参数,研究了多个励磁参考电压可控时系统的分岔点以及失稳模式的变化,给出系统在多励磁调节器(AVR)可控时的最大动态负荷裕度;以静止无功补偿器(SVC)补偿极限B0_max和控制电压参考值Vrefc为可控参变量,分别研究其对系统各种分岔的影响,并着重分析了对Hopf分岔的影响;研究了SVC附加控制对系统阻尼和动态负荷裕度的影响.所有仿真均在WSCC 3机9节点系统实现.     

负荷模型对电力系统动态稳定的影响

随着大区电网的互联,低频振荡在我国电力系统中已成为突出的问题.本文研究电力系统的负荷模型对电力系统动态稳定的影响.通过搭建单机无穷大系统,理论上研究送端负荷分别采用恒功率,恒电流及恒阻抗模型时,分析其与自动电压调节器及电力系统稳定器的相互作用对电力系统动态稳定的影响.通过对一个两区域四机系统的典型实例,利用PSD-BP...     

Verification and expansion of a method of transient analysis of voltage collapse based on the induction motor load model

Voltage instability is now under intensive study in Japan, and some dynamic methods for analyzing voltage collapse have already been presented. However, the suitability of load models used in the methods and the generality of the results have not been verified. In this paper, useful voltage collapse data acquired in real power systems are presented. The measured data are compared with the result of dynamic digital simulation to verify the suitability of an induction motor load model. In the latter half of this paper, dynamic simulations of voltage collapse with consideration of generator dynamics are carried out. An interconnected power model system with 10 nodes is analyzed. The generality of basic characteristics concerning voltage collapse which have already been obtained without considering generator dynamics is verified by such simulations.     

基于广域量测数据的电力系统自动切负荷紧急控制算法

在研究频率稳定分析直接法的基础上,结合广域量测技术,提出了自动切负荷控制算法。该算法不需要确定暂态衰减结束后的系统参数量,直接利用扰动后瞬间的广域量测数据来计算雅可比矩阵,从而预测出系统在扰动后的稳态频率以及保证系统稳态频率为整定值的切负荷量。算法计及了系统在扰动过程中的网损变化以及原动机实际阀门限制情况。利用PSS/E仿真软件,针对WSCC 9节点系统对所提出的算法进行了仿真验证,仿真结果证明了所提出算法的正确性。     

基于PSS/E的电力系统机电暂态负荷模拟

介绍了PSS/E仿真软件所提供的LDFR模型、IEEL模型等静态负荷模型,CIM5模型、CIMW模型、CIM6模型等感应电动机模型和CLOD综合负荷模型,叙述了各个负荷模型在PSS/E 14机59节点系统实例的机电暂态仿真中的具体实现方法,仿真结果说明了不同的负荷模型对电力系统动态仿真的影响.     

An interim dynamic induction motor model for stability studies in the WSCC

An "interim" composite load model containing a static part and a dynamic part has been implemented in the Western Systems Coordinating Council (WSCC). The static part of the load model is about 80% of the total load and comprises of existing static load data from the WSCC members. The dynamic part is a default induction motor model for approximately 20% of the total load. This composite model is used for all loads in the full-scale WSCC grid models that are the basis for system interconnection studies. The model is designed primarily to capture the effects of dynamic induction motor loads for highly stressed north to south flow conditions during summer peaks in the WSCC.     

Dynamic model for power systems with multiple FACTS controllers

Computer simulation and analysis of power systems are necessary for both planning and operation. This requires an appropriate mathematical model of the system that includes many inter-related linear/nonlinear differential and algebraic equations. Such mathematical model is also needed for the design of globally coordinated controllers to improve power system dynamic performance and stability. This paper presents a procedure for finding comprehensive dynamic models of power systems fitted with shunt and/or series connected FACTS controllers such as STATCOM, SSSC, and UPFC. In this procedure, individual components of a power system are modeled using appropriate frame of references. Then all related equations are transformed to a common network frame of reference and tied to each other through the Y-matrix of the transmission network. The procedure is tested on the Western System Coordinating Council (WSCC) test system including FACTS controllers by performing computer simulations of the system for three-phase short circuit faults. MATLAB/Simulink software package is used for the simulations.