Research On Dynamic Equivalent And Rapid RTDS Modeling Method For Large-scale AC/DC Power Systems

With the interconnection of regional power grids and the development of high-voltage direct-current(HVDC)transmission technology,China has formed the largest AC/DC hybrid power grid with the highest voltage level in the world.The security and stable operation of power grids is facing new challenges.In order to accurately analyze the operating characteristics of large-scale AC/DC hybrid power grids,the demand of electromagnetic transient simulation for large-scale power systems is getting increasingly significant.However,the low efficiency of electromagnetic transient simulation and the lack of electromagnetic transient data for large-scale power systems are the key factors restricting the application of electromagnetic transient simulation in the actual large-scale power grids.Therefore,this paper has conducted intensive research on the dynamic equivalent and rapid RTDS modeling method for large-scale AC/DC power systems.The main content is as follows:(1)A dynamic equivalent method for three-sequence network applied to electromagnetic transient simulation of AC/DC power systems is proposed.On the basis of dynamic equivalent method for physical equivalence,this method improves the standard equivalent structures of low-voltage networks,and performs equivalence on all three-sequence networks.Combined with a practical engineering method of parameter aggregation of equivalent generators and selection of controller models,this method can keep the dynamic characteristics of the system approximately unchanged before and after equivalence.The equivalent system does not contain negative resistance branches,negative resistance or negative reactance transformers,and is suitable for further building electromagnetic transient simulation models.The simulation results of large-scale AC/DC power system in East China Power Grid show that the proposed dynamic equivalent method can greatly reduce the system scale while preserving the steady-state and dynamic characteristics of the original system.(2)The rapid RTDS modeling method of large-scale AC/DC power system is studied.In this paper,a set of process method for uniformly converting various commonly used electromechanical transient data files into RTDS models is proposed,and the rapid modeling based on RTDS is achieved through automatic data conversion.This method is based on the data conversion function of RSCAD software,and uses PSS/E file as an intermediate file to unify the data conversion methods from different electromechanical transient software to RTDS,greatly reducing many repetitive work.The model correspondence of key components is compared,the existing problems in PSS/E-RSCAD data conversion are analyzed,and the key technologies of rapidly modeling large-scale AC/DC system in RTDS are introduced from the following aspects: abstract modeling of power system,dynamic equivalence,data preprocessing and data conversion,which provides a feasible way to build the full electromagnetic transient simulation models based on RTDS from the electromechanical transient data files.(3)The power system dynamic equivalence software and data transplant software are developed.Qt/C++ software is used to design and develop dynamic equivalence and data transplant software.The software structure and instructions are given,which provides a set of effective tools for building RTDS models quickly.Compared with the way of manually building RTDS models referring to electromechanical transient data files,using the two sets of software developed in this paper can realize the rapid modeling of large-scale system in RTDS with very low error rate,effectively reducing the modeling workload and debugging time.The actual application case of large-scale AC/DC power system in East China Power Grid validates the effectiveness and accuracy of the proposed rapid RTDS modeling method and the developed software.