Impacts of variable renewable generation on thermal power plant operating regimes

摘要

The integration of variable renewable energy sources (VRE) is likely to cause fundamental\udand structural changes to the operation of future power systems. In the United Kingdom (UK),\udlarge amounts of price-insensitive and variable-output wind generation is expected to be deployed\udto contribute towards renewable energy and carbon dioxide (CO2) emission targets.\udWind generation, with near-zero marginal costs, limited predictability, and a limited ability to\udprovide upward dispatch, displaces price-setting thermal power plants, with higher marginal\udcosts, changing flexibility and reserve requirements. New-build, commercial-scale, and low-carbon\udgeneration capacity, such as CO2 capture and storage (CCS) and nuclear, may impact\udpower system flexibility and ramping capabilities. Low-carbon generation portfolios with\udprice-sensitive thermal power plants and energy storage are therefore likely to be required to\udmanage increased levels of variability and uncertainty at operational timescales.\udThis work builds on a high-resolution wind reanalysis dataset of UK wind sites. The locations\udof existing and proposed wind farms are used to produce plausible and internally consistent\udwind deployment scenarios that represent the spatial distribution of future UK wind capacity.\udTemporally consistent electricity demand data is used to characterise and assess demand-wind\udvariability and net demand ramp events. A unit commitment and economic dispatch (UCED)\udmodel is developed to evaluate the likely operating regimes of thermal power plants and CCS-equipped\udunits across a range of future UK wind scenarios. Security constraints for reserve and\udpower plant operating constraints, such as power output limits, ramp rates, minimum up/down\udtimes, and start-up times, ensure the operational feasibility of dispatch schedules. The load factors,\udtime spent at different loads, and the ramping and start-up requirements of thermal power\udplants are assessed. CO2 duration curves are developed to assess the impacts of increasing wind\udcapacity on the distribution of CO2 emissions. A sensitivity analysis investigates the impacts\udof part-load efficiency losses, ramp rates, minimum up/down times, and start-up/shut-down\udcosts on power plant operating regimes and flexibility requirements. The interactions between\uda portfolio of energy storage units and flexible CO2 capture units are then explored.\udThis multi-disciplinary research presents a temporally-explicit and detailed assessment of operational\udflexibility requirements at full 8760 hour resolution, highlighting the non-linear impacts\udof increasing wind capacity. The methodological framework presented here uses high spatial-and\udtemporal-resolution wind data but is expected to provide useful insights for other VREbased\udpower systems to mitigate the implications of inadequate flexibility.