Abstract: In order to maintain the safe operation of the power grid and reduce the disturbance of small power sources to the power grid system, how to connect and cut off small power sources in substation protection is a key issue after the integration of small power sources into the large power grid. This article takes the transformation of a small power source project with low voltage conventional protection in a 110 kV intelligent substation as an example to analyze the impact of small power sources on the substation after they are connected to the grid, the additional protection functions that need to be added, and the solutions to the incompatibility between conventional protection and intelligent stations. It has engineering reference value.