Distributed generations and renewable energy generations have been widely installed in the distribution systems all over the world. The intermittence of distributed renewable energy generations and their special characteristics have various impacts on power system operation and dispatch. In this paper, the impacts of distributed generations on dispatch modes of power systems are discussed based on the Guangdong power grid in China. We introduce the situations of Guangdong power system, and its installation of distributed generations. The impacts of various distributed renewable energy generations on the system dispatch from the system operator's view point have been discussed. Based on the Guangdong existing generation resources and potential distributed generation grid integration, we provide suggestions to smooth the future integration of large amount of distributed renewable energy generations.