考虑相位约束的直流配电系统小干扰稳定性分析OA

As the DC source-load equipment such as distributed photovoltaics and electric vehicles increases,the stability analysis of DC distribution systems becomes more complex,where in the DC-side impedance of a voltage-source converter(VSC)interacts with its AC-side counterpart and may cause system instability.Most existing studies on small-signal stability are only qualitative,and quantitative evaluation of system stability is rarely addressed.Taking droop-controlled DC distribution systems as the research object,this paper establishes the VSC DC-side equivalent impedance and the load-side impedance models,and further reduces the order of the DC-side equivalent impedance model.Based on the impedance-ratio forbidden-region criterion and the phase constraint condition,and with consideration of the gain margin and phase margin,a quantitative evaluation index for system stability is developed.Meanwhile,the stable intervals of the index are depicted to intuitively illustrate the influence of various parameter variations on system stability.Finally,the theoretical analysis is verified through simulation and hardware-in-the-loop experiment.