Load Modeling And The Research Of Impact Of Composite Load Characteristics On The Transient Stability Of Actual Grid

As an important foundation of power system analysis, new research progresseshave sprung in the domestic and international field of power system load modeling.Generally speaking, load modeling can be divided into three ways: Component-basedmodeling approach, measurement-based modeling approach and fault-based modelingapproach. Comparatively, the first two ones are more common. Based on measureddata, measurement-based modeling approach will have to spend more on equipment. Itis limited in practice also for its long period to obtain ideal data. Freed from measureddata, component-based modeling method is widely used in power system. However,conventional component-based modeling method has failed to make a fullconsideration of geographical dispersion and random time-variability of load, thusbringing certain accuracy problem into cases, especially in area abundant insmall-capacity hydropower which will greatly affect the load model. As a result,realizing the on-line composite load modeling and small-capacity hydropowercomposite equivalent modeling is of great value.This paper has focused on load modeling of actual grid and analyzing the impactof composite load model characteristics on the transient stability. The work can besummarized by five following points. Firstly, regarding the geographical dispersion ofengineering application of load modeling, online-classification approach based ontypical daily load curve is applied to load characteristics classification. And typicalsubstations have been extracted from each class as the major object forcomponent-based modeling. Secondly, conventional component-based modelingapproach is used to realize industry modeling. On basis of this, composite load modelof each typical substation can be obtained through electric quantity statisticalproportion of representative industries. As for time-variability, two load modelparameters on-line correction methods have been applied into actual grid loadmodeling. After comparing and analyzing these two methods, a relatively superior oneis chosen to modify the load model parameters of Shaoguan. Thirdly, with thoroughconsideration of small-capacity hydropower’s impact on grid’s transient stability, thecomposite equivalent model of small-capacity hydropower’s is completed withcapacity weighting method to further improve simulation precision. Fourthly, from theperspective of composite load model parameter simulation, an interface approachbetween load model and BPA transient stability simulation program is proposed as well as a BPA stable data interface administration system and a on-line modelingplatform. This has enabled the intelligent application of load model parameter in BPAtransient stability simulation and also made it very convenient for user to create loadmodel and modify load model parameters. At last, various load models are used inactual grid transient stability simulation to analyze the impact of generalized loadmodel forged from composite load model and small-capacity hydropower compositeequivalent model on transient grid angle stability, transient voltage stability and limitof line fault excision time. The results have demonstrated that the generalized loadmodel can improve the transient stability of the gird. Such a conclusion can yieldvaluable reference for the scheduling and operation strategy of actual grid.Currently, VC++programming has realized the modeling method in this paper onthe online-modeling platform of Shaoguan through hard work of the project members.The author of this paper has completed the interface design and development betweenthe platform and BPA to advance actual application of on-line modeling in real-timesimulation.