Abstract:Along with the interconnection of interval power grids，natural resources in different areas have been utilized sufficiently． But because of the weakness of some interval links caused by transmission corridor limit and so on，the send － end isolated power grid and the receiving － end isolated power grid will come into being easily if the splitting accidents happen， which will lead to the serious power imbalance of local system，and some problems about the stability of system frequency will come up． Taking the power grid of Altay as the objective of the research，the characteristic of governing system and the influence of governing system on frequency stability of isolated power grid are analyzed． It is obtained that the governing system of the unit with different capacity has different impacts on the frequency of isolated power grid，the governing system of hydroelectric generating set and the governing system of thermoelectric generating set have different impacts on the frequency of isolated power grid，and the cooperation between governing systems of hydroelectric generating set and thermoelectric generating set with different capacity has different impacts on the frequency of isolated power grid． The simulation with PSASP verifies the related conclusions，which has an important reference for the operation of actual power grid and the cooperation between the governing systems of hydroelectric generating set and thermoelectric generating set