Research On Electromagnetic Transient Simulation Of AC/DC

Large-capacity power transmission over long distance and grid interconnection are inevitable trends in power system development,and higher requirements are imposed on power system simulation.Shaanxi Power Grid is an important part of Northwest Power Grid of China.The comm utation failure of Baoji Converter Station at the central location will have a serious impact on the safety and stability of Shaanxi Power Grid or even Northwest Power Grid.It is necessary to use reasonable means to conduct electromagnetic transient simulation research.However,the basic data of dometic power grid are mainly used for electromechanical transient simulation at present,and there is a lack of the electromagnetic transient simulation data of large power grid.The following work has been completed around electromagnetic transient simulation and modeling of the AC and DC power grids in this paper:The study of the conversion of power grid component models and data,which achieves the conversion of models and data for electromechanical transient calculation to models and data for electromagnetic transient calculation.Regarding the power system simulation software PSASP and ATP-EMTP,comparing the models and data of generators,transmission lines,transformers and loads,the corresponding model conversion relations are obtained.Through a small power system with three machines and nine nodes,the conversion method and effect were verified.The study of the modeling method of AC and DC large power grids,which accurately models the AC system and DC system respectively,and integrates them into a unified large power grid.This paper proposes a conversion method based on a custom modulewith high versatility and simple implemention,which uses MATLAB to write an automatic conversion program to quickly convert PSASP AC grid data into data suitable for ATP-EMTP.The method of establishing the model of the converter and its control system using MODELS and TACS is mainly studied,and the DC part of the converter station is accurately modeled,which increases the flexibility of modeling.The data integration is carried out by taking the same node name at the boundary point and calling an external file to obtain the electromagnetic transient simulation model of the large power grid.The feasibility of the modeling method is verified based on the electrical data of Shaanxi Power Grid and Baoji-Deyang DC project data in PSASP.The study of the simulation of commutation failure of DC converter stations.Taking Baoji converter station as an example,the problem of commutation failure is analyzed when single-phase and three-phase faults occur on the AC bus of the inverter side,and the criterion of commutation failure is obtained.Since the electromechanical transient simulation cannot accurately simulate the transient process,in the actual calculation,the critical voltage of the commutation failure can be corrected according to the results of ATP-EMTP.The results of electromechanical transient and electromagnetic transient simulations are compared to further verify the correctness and effectiveness of the modeling method for AC and DC large power grids.