Aiming at the problem that traditional fault nature identification methods are difficult to adapt to the cluster access of renewable energy to large-scale power systems. This paper proposes a fault nature identification method for the large-scale renewable energy transmission system based on interlocking voltage waveform recognition. Firstly

the voltage characteristics of non-full-phase operation and the harmonic feeding mechanism of renewable energy are clarified. It is found that there is a significant difference in the waveform of single line terminal voltage before and after the arc extinction of transient faults

whereas for permanent faults the difference is extremely small. The differences can be consistently revealed by selecting the waveform benchmark and calculating the voltage difference integral root-mean-square (RMS) value. The adaptive threshold-based fault nature recognition method is constructed. Simulation results based on PSCAD show that the method does not limit the configuration of shunt reactors and is highly reliable with good noise immunity. The method is independent of fault location

transition resistance

and renewable energy penetration. It is able to realize the accurate identification of the fault nature when the clustered renewable energy accesses to the grid.