To mitigate the impact of photovoltaic (PV) control strategies on the protection of distribution network lines

this paper proposes a novel differential protection scheme based on fault component current amplitude

phase

and harmonic content information. When a short-circuit fault occurs in the distribution network

the response patterns of the inner and outer loop control signals of the PV grid-connection to different fault types and transition resistance levels are analyzed. Furthermore

by incorporating the control effects of the proportional-integral (PI) within the converter

analytical expressions for the fundamental wave and the second and third harmonic components of the fault current in the PV output are derived

and an equivalent model of the PV with parallel output from multi-frequency current sources is constructed. By synthesizing various fault component information

under low transition resistance

protection criteria are established using the amplitude-phase characteristics of the fundamental frequency of the fault component. Under high transition resistance

the protection’s ability to withstand transition resistance is enhanced by integrating the second and third harmonic content of the fault component

ultimately achieving an integration of PV control characteristics and differential protection scheme design. A simulation model is constructed in Matlab for verification

and the results demonstrate that the protection scheme can adapt to various fault scenarios and possesses strong tolerance to transition resistance.