Power System Electromagnetic Transient Simulation Research Articles

Research on Method of Power System Electromagnetic Transient External System Equivalence Based on Fault Current Distribution

随着电力系统的重要性越来越高，仿真作为预防事故的重要手段也显得尤为必要，为提高仿真效率一般将仿真区域外的系统做一个等值，而目前常见的两种等值方法Ward等值法和网络等值法各有优缺点且无法满足大系统多节点的要求。针对以上问题，本文提出了一种基于动态分区的电力系统电磁暂态仿真外部系统等值方法，用来满足大系统多节点情况下的仿真需求，并提出了存在的问题及未来的发展趋势。 Due to fact that the importance of electric power system is higher and higher, the simulation as an important means of accident prevention is very necessary. In order to improve the simulation efficiency, an equivalent area is generally used for simulation system. Two common equivalent methods, Ward equivalent method and network equivalent method, have its advantages and disadvantages and cannot satisfy the requirement of large system more nodes. This paper, to solve above problems, according to a research unit based on the research and development of dynamic partitioning of power system electromagnetic transient simulation software, studies the use of two kinds of common external system equivalence method and dynamic partitioning method, and puts forward the existing problems and future development trend.

Simulation Research on Photovoltaic Power System Electromagnetic Transient Model

With an increasing number of photovoltaic (PV) power stations integrated into the power grid, a model which is suitable to be used in the power system electromagnetic transient simulation is required. So in this paper, a detailed PV power system model is provided. In the model, the core components, such as PV array and inverter are all considered. Then in a certain case, which contains a PV power system, are simulated and analyzed. The results show that the model could reflect the electromagnetic characteristics of PV power system effectively.

A High Frequency Strictly Passive Model for Transformer Based on the Image Method under Lightning Overvoltage

In the power system electromagnetic transient simulation, the establishment of a stable power transformer simulation model is crucial. Therefore, the high frequency strictly passive model of the transformer is investigated, which is suitable for the lightning strokes. The proposed model is introduced based on two-port network theory where its scattering parameters are measured through network analyzer firstly, and then the scattering parameters are transformed into the impedance parameters, finally the transformer T-equivalent circuit is established. The image method is used to fit frequency dependent impedance parameter, and according to different types of the parameter, the combination of circuit elements R, L, C is needed. By using the image method the values of the elements achieved are all positive and the strictly passive conditions of the circuits are guaranteed. Furthermore, the experiment and simulation results of a 10kV single-phase transformer under lightning overvoltage is presented, confirming the validity of the proposed method.

A new method of frequency-dependent network equivalence for power system

Electromagnetic transient simulation for large-scale power system is a time-consuming problem. A new frequency-dependent equivalence method is presented in the paper, which might significantly accelerate power system electromagnetic transient simulation. In the method, an effective algorithm is designed to directly transfer the port admittance determinant of external system’s mixing matrix into admittance rational function; and the step-by-step strategy for the equivalence of actual large system is put forward, which further reduces the calculation quantities needed. Moreover, the study of multiple real root pole characteristics of admittance transfer function of two-port network is performed and a proposition is achieved. Based on the proposition and residue theorem, the equivalence system for external system corresponding to the admittance rational function is obtained. The computation complexity of the step-by-step equivalence method is about o(⌋n/np⌉×t)(⌋⌉ is upper integral operation, n is the total buses number of external system, NP is the total buses number of single step equivalence network, T is single step equivalence time), which indicates that the computation complexity of the method proposed has nearly linear relationship with the buses number of external system, and the method proposed has satisfactory computation speed. Since the mixing matrix of external system includes all the information of external system, therefore, port admittance rational function derived from it can reflect its full frequency characteristic and the equivalence network achieved has high equivalence precision. Moreover, since the port rational function is gained at the condition of the external system without source, which equals stable passive network, it could not show any unstable pole and need not extra measure to make the equivalence system stable. The test results of the samples and comparison with other methods demonstrate that the new method proposed is valid and effective.

A study on parallel processing of electro-magnetic transient simulation

This paper presents a parallel processing method for power system electromagnetic transient simulation. It describes an outline of the algorithm, improvement in combined calculation between generators and networks, the relationship of granularity of divided subsystem and execution time and evaluation of precision by comparison with the results of EMTP. >