| With the further exhaustion of traditional fossil energy and the increasing environmental pollution caused by its combustion,the pace of energy transformation in all countries in the world is accelerating,and the proportion of solar energy,wind energy and other new energy generation in the power system is increasing day by day.However,with the increase of new energy generation facilities,power electronic devices are more used in all aspects of the power system,which further promotes the trend of electricity electronation in the power system.The dynamic characteristics of the power system dominated by synchronous machines in the past have changed.The gradual decline of power grid intensity has become a major concern.In the case of weak power grid,the access of new energy equipment will bring a lot of harmonics.On the other hand,the complex coupling between power grid and new energy equipment will also endanger the safety and stable operation of power system.Therefore,more and more attention has been paid to the stability of new energy equipment system.This paper takes the three-phase converter system based on LCL filter as the research object,analyzes the converter structure,establishes the mathematical models in ABC,α βand dq coordinate system in Matlab/Simulink,and analyzes the performance and parameter design method of LCL filter in detail.The performance and parameter design method of LCL filter are analyzed in detail.Secondly,the structure and control strategy of the converter system are studied,its dynamic model is derived,and its admittance matrix is derived.Thirdly,the oscillation components in the system are described uniformly by defining the conjugate original components and dual components in the complex space,and the equivalent complex circuit of the system is established accordingly to intuitively show the interaction between the power grid and new energy equipment.On the one hand,the stability of small disturbances can be analyzed,and on the other hand,the response of the system can be analyzed.Finally,the stability of the system is verified by simulation in software.This paper introduces the basic working conditions of the hardware in the loop experiment platform,constructs the main circuit in the semi-physical simulation instrument Typhoon 602,and performs the task of digital control together with DSP chip TMS320F28335 and FPGA chip XC3S400PQ208.The load mutation dynamic experiment and impedance switching dynamic experiment of the three-phase converter system based on LCL filter were carried out by Hardware-In-the-Loop platform.The results show that the oscillation of the system is equivalent to that of the equivalent prior-dual complex circuit and the stability analysis method is correct. |
