Study On The Digital-physical Hybrid Simulation System Based On Current Source Converters

In recent years, the development of micro-grid, distributed power generation andrenewable energy is rapid. At the same time, the study of interactions between micro-gridand power grid becomes very important while its application is more and more widely. Forsuch research, the real-time simulation of power system is an efficient and convenient tool,but both the traditional digital simulation system and physical simulation system cannotsatisfy the demands of the complicated power systems research. So combining the advantagesboth of them, the technology of digital-physical hybrid simulation is put forward. And thecurrent source type meets the situation when the impedance of small systems in digital sideis larger than the impedance of big system in physical side, which has better flexibility andis more suitable.This thesis first set up the overall structure of the digital-physical hybrid simulationsystem, and the interface of the physical side is the key object to study. According to thecharacteristics of the simulation system, select the three-phase rectifier and single-phaseinverter as the main circuit topology of the physical interface. Considering the stabilityproblem of digital-physical hybrid simulation system, this paper puts forward thecompensation algorithm based on the ideal transformer model and has verified the algorithmthrough the MATLAB. A Main research of this paper is the realization of the current sourceconverter. The scheme of controls and PWM signals with three-phase rectifier and single-phase inverter are given respectively, and built simulation models in the MATLAB for thesimulation experiments of steady state conditions and the dynamic conditions. Then, put therectifier and inverter in series to simulate the whole interface unit. A small micro-grid systemmodel is built to do the digital-physical hybrid simulation and compare with the digitalsimulation. The result of simulation shows that the rectifier can provide a stable dc currentsource, and the inverter can trace most of the waveform from the digital system, thus theinterface can satisfy the requirements of the digital-physical hybrid simulation system, andthe result of the digital-physical hybrid simulation is consistent with the digital simulation,which shows that the interface unit can realize the real-time simulation for the power system.