Study On Influence Mechanism Of Load Mutation On DC Microgrid Power Quality

Microgrid is being promoted because of its ability to realize local consumption of distributed power and flexible use of energy.The DC microgrid has unique advantages in terms of power density and energy utilization efficiency and is therefore favored in industrial field.However,the DC microgrid in the industrial field needs to supply power to precision equipment while carrying a large power load.Therefore,there is a high demand for power quality.For power quality problems with sudden changes in load on DC microgrids with high power loads,scholars at home and abroad have rarely studied systematically.However,some literatures have analyzed some specific power quality phenomena of DC microgrids.In order to achieve high power density operation of DC microgrid with higher power density,this paper uses a new type of three-level H-bridge DC converter as the energy interface of medium-voltage DC distribution network and low-voltage DC microgrid,and connect two types of high power loads in a low voltage DC microgrid.In such a direct current micro-grid topology,the power quality of the DC microgrid is analyzed and discussed in detail for power load mutation.First,the reduced-order model of the converters in the topology of the DC microgrid in this paper is modeled.The three-level H-bridge DC converter is used as the source converter,and the three-phase inverter and the DC chopper are used as load converters.Find the respective linearization model and the related input and output impedances.Then based on the model of DC microgrid converters,the causes of the ripple problems in different frequency bands in the steady state operation of the DC microgrid are analyzed,and the ripple effects in the parallel operation of multi-converter are analyzed,and qualitively discuss the corresponding changes and determinants of various ripples.The large-signal DC microgrid is modeled when the power is suddenly changed.Based on the characteristics of the two kinds of high-power load mutations,the dynamic changes of the load caused by the two load mutations under different conditions are discussed,and the overall load changes are analyzed.The influence on the transient voltage fluctuation of the DC bus when the parameters of the DC microgrid are different.Finally,the steady-state power quality of the above-mentioned DC microgrid and the effect of load abruption on the power quality of the DC microgrid are summarized,and the outlook is given on the basis of the full-text work.