Research On Fast Simulation Method Of Electromagnetic Transient And Independent Software Development

With the introduction of the concept of a new power system with new energy as the main body,the demand for new energy power generation and grid connection will further expand,and the power system will show a "double high"with a high proportion of renewable energy and a high proportion of power electronic equipment.The characteristics,grid scale,proportion of DC transmission and the depth of AC-DC hybrid connection will all further increase.Compared with traditional synchronous generator sets,power electroni c equipment has the characteristics of small simulation time scale and fast dynamic response of equipment.The access of new energy power generation equipment and a large number of power electronic equipment has a significant impact on the stability of the power system.In order to reveal the operation rules and dynamic characteristics of the new power system,study its control methods and protection strategies,and ensure the safe and stable operation of the power grid,fast and accurate electromagnetic transient simulation is an indispensable technical means.However,the traditional electromagnetic transient simulation method is difficult to balance the accuracy and speed of electromagnetic transient simulation,and the current electromagnetic transient simulation software can no longer meet the efficient and accurate simulation requirements of new power systems.Therefore,it is an important part of the construction of a new power system to study the rapid simulation of electromagnetic transients and develop an independent and efficient electromagnetic transient simulation platform.The thesis has carried out the following research work on the rapid simulation of electromagnetic transient and the development of independent electromagnetic transient simulation software:(1)Research on fast simulation method of electromagnetic transient stateDue to the time-varying admittance matrix of the voltage source converter(VSC)electromagnetic transient detailed model,the simulation efficiency is low when simulating a large power grid with large-scale new energy stations.To solve this problem,based on the principle of semi-implicit lantency decoupling,this paper proposes a decoupling model with simple decoupling circuit,constant admittance matrix,and taking into account the internal characteristics of the converter.Firstly,starting from the state equation of the VSC converter,using matrix splitting and delay techniques,the half-step time delay models of the DCside capacitor-grounded VSC converter and the DC-side capacitor-ungrounded VSC converter are respectively constructed to realize the AC-DC side.Decoupling;then use the characteristics of mutual exclusion and conduction of the vertical commutation of the upper and lower bridge arms of the VSC to simplify the calculation of the parameters of the decoupling model,so that the admittance matrix of the system is kept constant,and the calculation speed is further improved.The numerical results show that the proposed method improves the calculation speed while maintaining high accuracy.Finally,the accuracy and rapidity of the semi-implicit lantency decoupling model are verified by VSC converter grid-connected system and IEEE 14 node examples.(2)Electromagnetic Transient Network Parallel ComputingThe sub-network and parallel computing method is an effective means to realize the rapid simulation of power electromagnetic transient simulation,and its characteristics need to be analyzed in the selection and design of the sub-network and parallel computing method.This paper studies the currently commonly used sub-network and parallel algorithms,and analyzes the characteristics of their algorithms.Combined with the characteristics of the current electromagnetic transient simulation of new power systems,it summarizes the basic requirements and implementation directions for designing and selecting sub-network parallel algorithms.It can be seen that the semi-implicit latency decoupling model is suitable for new power system simulation.(3)Development of independent electromagnetic transient simulation softwareThis part makes a preliminary study on the independent electromagnetic transient simulation software.Firstly,the business process of the electromagnetic transient simulation software is analyzed.Based on the idea of object-oriented programming,the class diagram structure of each functional module is designed.The VSC test example and the IEEE118 node test example system verify the accuracy of the calculation of the AC part and DC part of the program,as well as the verification of the simulation capability of the multi-node system.The calculation results are completely consistent with the PSCAD accuracy.