Research On The Practicality Of The Measurement-based Load Model In Large Grid

With the increment of the relationship between power system planning and simulation, how to improve the validity and the practicality of the models so as to make the simulation results more scientific and reliable has been a key point in power research field. As one of the power system components, load is most complicate and hard processed. Although there has been a large improvement in measurement-based load modeling, through the whole county, the static and dynamic load models based on the typical parameters are always used in large system simulation while the researching results have not been put into practice to guide the power operations and planning. There are many reasons resulting in that, one of which is the problems encountered in the load model practicality have not been well solved.According to the problems coming up in the load model popularization, four aspects such as model-precision improvement, load time-variant characteristic elimination, load model extension, the build and revisal of the load model database are investigated step by step.Specifically, the trajectory sensitivity is first utilized in parameter range adjustment by which the model precision is highly improved under the condition of unchanging the model structure and identification algorithm. But it should be realized that it is not enough for the load model practicality to just possess the load model structure and good parameter identification algorithm. The load changes all the time which also makes the load modeling one of a most difficult problems in power system, with respect to that, cluster analysis is applied to eliminate the time-variant characteristic in load modeling. A more simple method is proposed after the research above which is also verified by the parameters'trajectory sensitivity.By the steps above, a more precise load model can be built for the load points which have the field data. But in a large power grid, it is not reality to derive the field data of all the load points, generally, only few points are available. Due to that, more researches on load model extension in large grid which may have different field data are carried out based on the stepwise multiple regression, the strategy of load model extension for different load data situation is also proposed. For the users' convenience, large-area load model parameters should be arranged into a database, mean the while, the load characteristic varies in long time span, so the load database should not keep constant as that of generators', it should be revised periodically. Therefore, the strategy of the load model database construction and revisal is studied which provides the guidance for the load model practicality.Because the traditional load models can't describe the load shedding characteristic under low voltage, an exploratory new load model suitable for low voltage transient stability analysis is presented, it can not only reflect the load dynamic property but also can indicate the phenomena of load shedding when large voltage disturbances happene. The research above purveys a new component in voltage stability analysis.In a word, the study of load model practicality in large grid accelerates the step of improving simulation reliability, by following the stages of model precision improvement, time-variant elimination, model-extension and model-database arrangement. Some problems coming up in the process of load model practicality are solved. In addition, a new load model was built innovatively, all the researches above advance the load model practicality and simulation reliability so as to enhance the reliability of the power system analysis.