Improving solar-induced grid-level flexibility requirements using residential central utility plants

This study discusses the expansion of an existing central utility plant (CUP) optimization model to analyze the effectiveness of using a residential CUP in Austin, Texas for improving the integration of solar into the grid. The CUP equipment includes a simple-cycle gas turbine (SCGT), battery, chiller plant, and chilled water storage (CHS). The analysis is accomplished by analyzing three sensitivity scenarios. Scenario 1 exposes the CUP to increasingly expensive demand charges. Scenario 2 limits the CUP's allowable ramp rate. Scenario 3 prohibits the CUP from selling electricity and requires it to provide ramping support to counteract the large ramp rates that occur in the net load during the evening when solar production diminishes but load continues to rise. The CUP effectively uses a chiller plant with chilled water storage (CHS) to change its operational behavior and provide grid-support support services. This support is limited, however, as more stringent circumstances require the CUP to invest in expensive SCGT or battery equipment, or to curtail solar generation.