Frequency response and dynamic power balancing in wind and solar generation

Large scale deployment of renewable resources introduces significant complexity in performing load balancing and ACE/frequency regulation. Wind and solar energy are intermittent which may diminish rapidly while system load is increasing. This operating condition places an additional burden on conventional resources that are on-line and available for load balancing and ACE/frequency regulation to meet the challenges surrounding the aspects of uncertainty and variability that come with having variable generation in the system. There are two major attributes of intermittent generation that notably impact system operations - variability (generation changes according to the availability of the primary fuel, i.e. - wind or sunlight in this case resulting in swings of the plant output) and uncertainty (magnitude and time of the generation output is unpredictable). While variability is more of a function of regulation, uncertainty can be aligned more to the need for ramping requirements. The objective of this paper will be to understand the feasibility of ramp rate limits within the present CAISO´s conventional generation fleet to meet renewable requirements in 2020 and determine the additional ramp capability required with the integration of renewables to CAISO footprint. Moreover, statistical analysis will be done to characterize the ramp effects and determine the worst hourly changes with renewable energy penetration.