Accurate identification of controller parameters is crucial to analyzing the dynamic characteristics of the inverter-interfaced photovoltaic system (IIPVS). However, the dynamic coupling of multiple control loops and low sensitivity of partial parameters hinder the overall identification accuracy of controller parameters in IIPVS. Given this, a measurement signal change disturbance-based identification method is proposed to obtain accurate IIPVS controller parameters. The measurement signal change disturbances are injected into the inverter input ports, decoupling controllers' dynamic characteristics. The local sensitivity is utilized to analyze correlations between controller parameters and fault transient currents, enabling optimal observation window selection and identification sequence. A stepwise identification method is proposed to resolve multi-parameter coupling challenges by leveraging the sensitivity difference between controller parameters. Finally, a modified 29-node test system connected with a PV farm validates the method's effectiveness.