Performance and Controls of Gas Turbine-driven Combined Cooling Heating and Power Systems for Economic Dispatch

Combined cooling, heating and power (CCHP) systems are power generation stations designed for maximum waste heat recovery and energy sustainability. In a conventional CCHP system, a gas turbine provides the electrical generation and the waste heat is recovered for cooling and heating. Traditionally, utility-scale CCHP plants of 100 MW or more were commissioned to support large industrial processing plants. Light industry, commercial, and institutional applications have adopted smaller CCHP systems to realize economic savings and environmental benefits. Besides facing operating constraints such as smaller foot-print, shorter reaction time and shorter control tolerances, these plants also encounter low energy demands because of diurnal or seasonal variations, forcing them to operate at part-load. Coupled with relatively high capital and O & M costs, compact CCHP stations then become uneconomical for end-users. From flexibilities in operation, however, there are ample opportunities for favorable economic dispatch by operating the plant under demand response programs and ancillary services. The small-scaled CCHP systems fall under the distributed generation (DG) category of many regulatory policies and electricity rate tariffs of utilities. Several typical rate structures applicable to CCHP systems were evaluated, including standby and non-standby time-of-use (TOU), and critical peak pricing (CPP). The economic analysis produced insights on novel and preferred chiller dispatch strategies for energy and demand charge reduction. The increased variability and uncertainty of renewable generation add to the balancing duties of grid regulators whom previously had to deal with such behaviors in system load. The situation is becoming direr for California, as the state mandates 33% renewable resource generation by 2020 along with a plethora of stringent environmental legislation that would displace 18,000 MW of traditional base-load plants by 2020. Therefore, ancillary services will become more valuable as grid balancing authorities such as CAISO seek to address the uncertainty and variability in renewable generation. A gas turbine-driven CCHP system is one example of an ancillary service provider capable of complementing the increased renewable penetration. This dissertation seeks to elucidate the feasibility of implementing CCHP technology to light industrial and commercial applications for favorable economic dispatch to complement demand response services and renewable integration.