	A virtual power plant is a system that integrates several types of power sources to give a reliable overall power supply. The sources often form a cluster of different types of dispatchable and non-dispatchable, controllable or flexible load (CL or FL) distributed generation (DG) systems that are controlled by a central authority and can include microCHPs, natural gas-fired reciprocating engines, small-scale wind power plants (WPP)s, photovoltaics (PVs), run-of-river hydroelectricity plants, small hydro, biomass, backup generators, and energy storage systems (ESS).