Research On Stability Of DC-DC Synchronous Conversion In Microgrids

With the continuous consumption of fossil energy and the deteriorating global environment,the issue of how to use renewable energy or clean energy has received wide attention.The microgrid is a supply management technology of distributed energy that realizes the maximum utilization of distributed power through flexible operation of grid-connected operation and island operation mode.The conversion of the power quality in microgrids will directly affect the utilization of distributed energy.DC voltage converters are an indispensable part of microgrids energy conversion devices.This paper mainly studies a cascaded DC-DC buck converter.A dual-loop PI control strategy is used for the synchronization state of intermediate bus voltage and load voltage in the cascaded DC-DC buck converter.The stability analysis for the cascaded DC-DC buck conversion system with dual loop PI control is performed.Two cascaded cascaded DC-DC buck converter is taken as a research object.the corresponding method can be extended to multiple cascaded DC-DC converters.The main work includes the following aspects:1.Modeling of cascaded DC-DC buck converters in energy conversion devices based on microgrids.In order to reduce the load on a single converter and meet the different power requirements in the operation of the microgrid,two cascaded DC-DC buck converter are studied.The cascaded DC-DC buck converter provides the voltage output of the intermediate bus and the load voltage for the microgrid,which can broaden the application range of the DC-DC converters.2.A dual-loop PI control strategy is proposed.The dual-loop PI control strategy can be used to track specific intermediate bus and load voltage values,reduce the ripples,and ensure that the intermediate bus voltage and load voltage can remain synchronized and the stability of the system.Finally,the system is simulated and analyzed to verify the effectiveness of the dual-loop PI control strategy.3.Based on the method of monodromy matrix and the method of small-signal analysis,the stability analysis of the cascaded DC-DC buck conversion system with dual-loop PI control is performed.By dividing the whole system into a number of different subsystems,the classical control theory and modern control theory are usedto analyze the jumping points of subsystems and subsystems,and the stability of the system can be analyzed.According to the results of the stability analysis,it is proved that the cascaded dc-dc buck conversion system with dual-loop PI control is stable.