In conventional power systems, load frequency control (LFC) or automatic generation control (AGC) is done using PI controllers implemented in steam turbine generator systems. In the PI controller, the proportional part represents droop of the governor and integral part restores frequency to nominal value by changing load reference set point of the turbine valve. In an isolated micro-grid electronically interfaced distributed generator (EI-DG) units are forced to participate in LFC along with synchronous generator based DG (SG-DG) units to ensure better transient performance of the micro-grid. In this paper, a centralized LFC using model predictive controller (MPC) is chosen as an alternative to the conventional PI controllers. The frequency control capability of a centralized discrete model predictive controller (DMPC) in an isolated micro-grid with photovoltaic (PV) and diesel generators is investigated using small signal dynamic models of the PV converter and SG-DG along with steady state power balance equations of the network. Simulations are carried out in MATLAB software package. � 2016 IEEE.