This paper presents a new model for optimum operation of a microgrid, consisting dispatchable supplier (microturbine), non-dispatchable supplier (wind turbine), energy storage system, and loads. It has the capability of energy exchanging with upstream distribution network and contains both controllable and uncontrollable loads. For the controllable loads by presenting a new controlling algorithms, the consumption of these loads is changed or postponed to another time, with regard to the uncertainties of wind generation and the energy price of upstream distribution network, and of course by considering the welfare level of consumers. On the other hand, Monte Carlo simulation method has been used, in order to model the uncertainties of wind generation, energy price of the upstream distribution network, power consumption of uncontrollable loads, and also the failure probability of units and disconnection probability from the network. In this method, various scenarios have been generated and involved in the operation optimization program with other required inputs for the next 24h. Finally, the proposed models have been simulated on a typical microgrid with two 200kW microturbines, one 400kW wind turbine, 300kWh battery bank, and some loads with about 420kW peak demand. Simulation results by considering uncertainties for the various proposed load management programs have been analyzed and show that by implementing these programs, total operation profit of microgrid is increased from about 47$ to 54$ per day.