Research On Multiport Disturbance Suppression Methods For Hybrid Energy Storage Converters

A direct current(DC)microgrid includes various types of ports such as photovoltaic(PV)cells and loads,which are coupled via a DC bus.The stability of the DC bus voltage is affected by disturbances from different ports and types.Adding a hybrid energy storage system(HESS)can effectively improve the stability of the DC bus voltage,and the hybrid energy storage converter as an interface is particularly important for ensuring the effective utilization of energy storage medium characteristics.This thesis focuses on the multi-port disturbance problem in DC microgrids and aims to stabilize the DC bus voltage by studying the multi-port disturbance suppression method of hybrid energy storage converters.Firstly,this thesis studies the influence of PV cell and load ports on the stability of the DC bus voltage in the DC microgrid,analyzes the disturbance characteristics of the DC bus voltage caused by the randomness of PV cell power generation and the uncertainty of loads,and clarifies the effectiveness of the HESS composed of batteries and supercapacitors in suppressing disturbances from these two types of ports.Secondly,the thesis compares and analyzes the existing methods of HESS access to the DC bus,selects the parallel half-bridge non-isolated bidirectional DC-DC circuit as the access method for battery and supercapacitor ports,and studies the energy flow relationship within the PV DC microgrid architecture under this access method.Based on this,the smallsignal mathematical model of the HESS in the bidirectional operating mode is established to provide a basis for the design of subsequent control strategies.Next,aiming at the typical operating mode of the HESS,and with the goal of stabilizing the DC bus voltage,the thesis designs an overall control strategy based on the proportional integral(PI)controller and power fractionator,and uses frequency domain analysis to tune the controller parameters for typical operating conditions.Considering the inadequacy of PI control in terms of regulation performance,a hybrid energy storage converter control strategy based on the dual-loop linear active disturbance rejection control(LADRC)is proposed,and a parameter design method based on the bandwidth method is given.The thesis builds a simulation model of the HESS in MATLAB/Simulink software,designs simulation experiments under different operating conditions,and compares and analyzes the two control strategies.The simulation results show that the hybrid energy storage converter control strategy based on the dual-loop LADRC exhibits better dynamic response and disturbance suppression capabilities in terms of power response and DC bus voltage support.Finally,this thesis built an experimental platform for the hybrid energy storage system based on TMS320F28035 microcontroller,which included the design and implementation of key hardware circuits such as the main circuit,control circuit,sampling circuit,and drive circuit.Load port disturbance experiments were conducted,and the experimental results showed that the proposed overall control strategy for the hybrid energy storage converter effectively utilized the complementary power characteristics of the battery and supercapacitor,and reduced the impact of port disturbances on the direct current bus voltage in the DC microgrid.