Abstract:

To address the issues of poor long-term operational capability and uncoordinated energy scheduling in DC microgrid systems coupled with photovoltaic （PV）， lithium batteries， supercapacitors （SC）， proton exchange membrane （PEM） electrolyzers， and micro gas turbines， a dynamic power distribution strategy based on the coordinated optimization of state of charge （SOC） of lithium batteries and hydrogen storage level （LOH） in hydrogen storage tanks is proposed. The strategy established a hierarchical coordinated control architecture： the upper control layer generated system power distribution methods based on the switching logic of four typical operating conditions and optimization targets for SOC and LOH； the lower control layer achieved dynamic power distribution among SC， lithium batteries， and the hydrogen energy system. Under this strategy， when PV output was insufficient， the micro gas turbine was activated for hydrogen-powered supply. When PV output was surplus， the residual power was dynamically distributed based on SOC and LOH to charge lithium batteries or generate hydrogen with PEM electrolyzers. This reduced the damage to the battery's lifespan caused by prolonged deep charge/discharge cycles. A DC microgrid model coupling PV， hydrogen production， energy storage， and micro gas turbines was established on the Matlab/Simulink platform and verified through simulations. The results show that the proposed power distribution strategy effectively regulates energy storage devices， appropriately allocates the surplus power， and ensures the efficient and stable operation of the microgrid.

Key words: DC microgrid, state of charge, micro gas turbine, power distribution strategy, photovoltaic, lithium battery, hydrogen storage tank