A Dynamic Equivalent Model Based On Component-based Approach

Recently, with the development of economy, the overall size of the national power network is expanding and the degree of grid interconnection of the provincial areas has gradually enhanced, which results a higher requirements on the voltage stability, transient stability and dynamic stability. As the terminal of the power network, the load has an important impact on the power network, which can’t be neglected. The impact of load models on power system digital simulation results is related to the electricity network operation, planning and decision-making. However, due to the time-varying, nonlinear and variable structural characteristics of the load, load modeling is still a difficult task. The conventional load modeling methods include the component-based and measurement-based ones, which always have some drawbacks. Due to the constant of field tests and directly measuring, the measurement-based method is hard to be applied by electricity workers. Thus, the component-based method is still a practical and effective method. Based on the component-based method, the author improves load modeling work.First of all, taking into account the differences of the regional load, this paper proposes the results of power system dynamic stability calculation as the initial data of load modeling. The set of data is not available, nor is experience, but can be calculated with the location or time change. Although it increases some computation, it provides a more realistic basis for load modeling work, which makes the flexibility of the load, such as time-varying and nonlinear characteristics no longer so difficult to be grasped. On the other hand, this method overcomes the drawbacks of the measurement-based method, i.e., the constant of field tests and directly measuring. It should be noted that the modeling data is a special value of a certain area over a certain period time, but the model of load is a common model. When the load changes, we only need to identify a common model with the changing data of load and then obtain the corresponding and special model parameters.Second, considering that the load modeling works often do not take into account the impact of the electricity network load in the current power system dynamic stability analysis, which leads to bad results in the current complex power network, the proposed load model, which utilizes the dynamic equivalence of power network and load, improves the accuracy of the load model.When the dynamic equivalent model is set up, we can obtain the response of load by using the incentive of the first side of the model. Numerical examples show that the proposed model has a high accuracy, with the practicality and effectiveness, can be adopted in practical work.