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逆变器诺顿等效电路的等效阻抗与电力系统发生耦合,是逆变器并网系统发生谐振的根源.该文首先对逆变器等效阻抗进行研究,建立逆变器精确数值模型,并与物理实测结果对比,总结提出逆变器阻抗特性.在此基础上,研究得到逆变器并网系统并联谐振的机理:在系统阻抗为阻感特性的情况下,若全部并网逆变器的电导特性均为正值,则并网系统稳定;若存在具有负阻尼特性的逆变器,则并网系统存在谐振风险.进而该文提出逆变器阻尼控制方法,在逆变器闭环控制稳定的前提下以逆变器电导在全频带为稳定正值为目标校正逆变器导纳特性曲线,使逆变器导纳特性满足维持系统稳定的条件.仿真与物理试验证明了该谐振机理分析方法与阻尼控制方法的有效性.“,”The equivalent impedance of the inverter's Norton equivalent circuit is coupled with the power system,which is the source of the resonance that caused by the grid-connected inverter.Therefore,this paper studied the impedance characteristic of inverters and proposed a stability criterion based on the impedance characteristic curve.Firstly,combined the theoretical analysis and the physical measurement results of the inverter's equivalent impedance,the impedance characteristic of inverters was studied to be inherent and negative at some frequencies.On this basis,the stability criterion of grid-connected inverters was obtained:in the case that the system impedance has resistance characteristic,if the conductance property of all the grid-connected inverters is positive,the grid-connected system is stable;if there is the inverter with negative damping characteristic,the grid-connected system has the resonance risk.Therefore,an inverter damping control method was proposed.In the premise that the inverter closed-loop is stable,the inverter impedance characteristic curve can be calibrated with the purpose that the inverter conductance is stable positive value in the whole frequency band,so the inverter impedance characteristic can meet the condition of maintaining the system stability.Simulation and physical experiments demonstrated the effectiveness of the analytical method and the control method.