LAUSR

In this paper, the effect of the increased penetration of microgrids (MGs) on the frequency control of power systems is studied. Considering the fast dynamic response of MGs and their distribution in the network, the conventional model of load frequency control may fail for their consideration in the frequency control system. In this paper, an appropriate dynamic model of MGs is developed for the system frequency control. Then, the MGs are classified into two different groups based on their distance to the conventional generation (CG) units. The distance is determined to measure the effect of MGs on the CG units. In the proposed classification method, one group consists of MGs, which have a considerable effect on a group of coherent generators, and the other group consists of MGs, which affect two (or more) noncoherent CG units. The coherence of CG units is determined by the oscillation modes of the power system. For the MGs near the coherent CG units, the measured bus frequency is used as the input control signal, and for the other group, the transferred active power deviation is utilized. Simulation results show the effectiveness of the proposed controllers to improve the system frequency stability.