Optimal joint-dispatch of energy and reserve for CCHP-based microgrids

With the rapid growth of distributed energy resources (DERs) and microgrids (MGs), the volatility of renewable generations will impact the economical and secure operation of the power system. To exert the grid-friendly manner of MGs, an optimal joint-dispatch scheme of energy and reserve is proposed in this study for combined cooling, heating and power (CCHP)-based MGs. In the scheme, the total operation cost of the MG is minimized under pre-defined reserve requirements. The energy demands are satisfied via dispatching various DERs. Distinguished from the electric demand balanced at any given instant, the unbalance between thermal supply and demand is acceptable because the temperatures can be maintained due to the thermal inertia. When the electric supply is in shortage, the energy provided for the thermal systems can be temporarily reduced so that more energy can be utilised to support the electrical systems. The dynamics of the MG is modelled by discretising thermal balance differential equations. With the coordination of CCHP systems, the reserve capability of the MG is fully utilised, thereby ensuring the security of the bulk power system. Case studies based on an industrial park in Chicago, USA validate that the proposed scheme can provide more reserve capability.