Abstract: With the continuous increase in the penetration rate of photovoltaic new energy in the power system, its nonlinear and fluctuating characteristics have an increasingly significant impact on the fault characteristics of the system. Traditional fault analysis theories are difficult to adapt to new scenarios and face severe challenges. This article conducts a systematic study on the dynamic evolution of power system fault characteristics in high proportion photovoltaic grid connected scenarios. Firstly, the three types of fault response mechanisms, namely external suction effect, boosting effect, and reverse overcurrent effect, are revealed through photovoltaic grid connected scenarios, and the correlation law between photovoltaic penetration rate and fault current amplitude and phase is quantified. Secondly, a dual verification method of digital simulation and physical experiments is adopted to compare the changes in fault characteristic quantities under different photovoltaic penetration rates, fault types, and locations. On this basis, extract the phased evolution law of fault characteristics with the increase of penetration rate and the change of fault location, and clarify the differential impact of three types of mechanisms on protection configuration. The research results can provide theoretical support for fault diagnosis, protection optimization, and stability improvement of high proportion new energy power systems, and have significant engineering application.