The Research on Bus Voltage Stabilization Control of Off-Grid Photovoltaic DC Microgrid under Impact Load

The solar power generation includes certain randomness and volatility, coupled with dynamic load involved in power fluctuations, which renders microgrid having certain unplanned instantaneous power during the process of real-time operation, so as to affect the stability of DC bus voltage. This paper, through constructing a model of off-grid photovoltaic DC microgrid under impact load characteristics, aiming at the fluctuate problems of the DC bus voltage caused by impact load, puts forward a fast response of hybrid energy-storing system composed of supercapacitors and batteries and superiors peak regulation capability to shave the peak and fill the valley of the microgrid. The researches on the strategy of double closed-loop voltage stabilization of blended energy storage system are made and the shortcomings of the double closed-loop voltage control of voltage and electricity are analyzed. And based on this, the tactics of new and double closed-loop voltage control of inner ring of power and the energy outer ring of DC bus capacitance are put forward and examined by simulation and experiment. The experiments prove that this method can more effectively suppress the influence of the fluctuations of impact load power on the DC bus voltage and further improves the system’s stability.