Microgrids (MGs) are small scale power plants that are located directly at the load centers. The use of MG reduces considerable power losses, improves efficiency and reliability. They are also considered to be more suitable along with renewable energy-based sources in the distribution system. The use of Renewable Energy Sources (RES) provides a good impact on the environment. Dynamic economic dispatch carries out optimal scheduling of all generating units that helps in minimizing the generation cost. In the micro-grid environment, it allows different Distributed Generations (DGs) to coordinate among themselves over the requisite periods simultaneously satisfying the operational constraints. In this paper, a microgrid system has been considered that includes wind turbines (WT), photovoltaic (PV) arrays, diesel engines (DEs), a fuel cell (FC) and a battery. The battery helps to provide power to fulfill the demand when load attains peak values in standalone mode. For the spinning reserve, the probability constraints are defined to take care of the fluctuations based on the weather and environmental changes and faults in the microgrid system. A global optimization technique, Cuckoo Search Algorithm (CSA) is used, to minimize the overall operational cost and the pollutant treatment cost for four different operating strategies. All simulations are carried out using MATLAB R2018a. © 2019 IEEE.