Abstract: The modern power system is developing towards large-scale and wide-area, and district control cannot fully realize the stable operation of the entire system, which makes the power system begin to rely on open communication networks, and the problem of communication time lag in the system becomes more and more serious. The novel integrated system model was constructed through considering the communication time-delay and the renewable energy fluctuation, then the load frequency control (LFC) was proposed to reduce the frequency deviation. Meanwhile, the sliding mode (SM) method was used to optimize the LFC which can raise the stability of integrated renewable system with mismatched uncertainties and communication delay. Furthermore, the output power of wind turbine generator (WTG) can also actively respond to system frequency changes based on the integrated model. At last, it is proved that the control strategy put forward in this paper can lessen frequency fluctuation by using the RTDS device under various load disturbance and communication delay operating conditions.