Research On Parallel Operation Control Strategy Of Microgrid Inverter Including The Hybrid Energy Storage

Renewable energy generation, the inverters and energy storage system compose the microgrid, the flexible operation modes of the microgrid for the stability of power system improve the strong support and guarantee it to be a high power supply reliability. Different distributed power using different control methods is imperative due to the variety of distributed power in the multiple inverters parallel operation microgrid system. As a important part of energy exchange in microgrid, reasonable control of inverters becomes the key to the microgrid stable and reliable operation.In this paper, after study the basic principle, establish the mathematical model, analyse the simulation of charge and discharge characteristic, the lead-acid battery and super capacitor are used to construct hybrid energy storage system. Then make a research on the control strategy in detail for the system, which contains the Bi-directional DC/DC converter and the multi-hysteresis control strategy. Verify the superiority of the hybrid energy storage system compared with the only energy storage battery system.In hybrid energy storage inverters in parallel operation system, the inverter control is very important. When the traditional droop control method is adopted, the line impedance inconsistencies may lead to circulation and serious damage the system stability. Join the virtual impedance can make the power split effect better, but make the system steady state performance decrease, and power allocation still has a deviation. To eliminate the circulation of system caused by unbalanced line impedance and make the inverter output power split, this paper analyzes the reasons of power split exist deviation, designs an improved droop control scheme to make the inverters split power according to the capacity without the influence of the line impedance and design parameters. At the same time, the power split effect is better and the steady output voltage is lower. The simulation results prove the effectiveness of the improved droop control method.Verifiy the accuracy of theoretical derivation and simulation analysis, through the parallel three-phase inverter experimental platform based on TMS320F28335 DSP.