Multi Energy System (MES) concept was introduced to improve the efficiency of conventional energy systems, reduce air pollution as well as cost reduction. In addition, the flexibility of MESs allows a higher penetration of renewable resources. Basically, MES is a combined system to simultaneously produce heat, electrical power and even cooling power. This system benefits the advantages of both traditional and renewable energy carriers. However, when it comes to optimal operation planning of the utilised energy converters with the aim of cost reduction and efficiency enhancement, the design of Energy Management System (EMS) becomes more of a challenge. This paper proposes a generic and accurate dynamic operation model considering the variable efficiencies and the transitional status of energy converters. It also includes the variability of the operational cost of energy storages and demand response. The developed model is applied to achieve the optimal dispatch plan and operation of MES employed to provide power heat and electricity demand for a university campus. The results verify the effectiveness and functionality of the proposed method.