Analyzing the Impact of Solar Power on Multi-hourly Thermal Generator Ramping

Solar power generation, unlike conventional forms of electricity generation, has higher variability and uncertainty in its output, because solar plant output is strongly impacted by weather. As the penetration rate of solar capacity increases, grid operators are increasingly concerned about accommodating the increased variability and uncertainty that solar power provides. This paper illustrates the impacts of increasing solar power penetration on ramping of conventional electricity generators by simulating the operation of the Independent System Operator -- New England (ISO-NE) power system. A production cost model was used to simulate the power system under five different scenarios, one without solar power and four with increasing solar power penetrations up to 18%, in terms of annual energy. The impact of solar power is analyzed on six different temporal intervals, including hourly and multi-hourly (2- to 6-hour) ramping. The results show how the integration of solar power increases the 1- to 6-hour ramping events of the net load (electric load minus solar power). The study also analyzes the impact of solar power on the distribution of multi-hourly ramping events of fossil fueled generators, and shows increasing 1- to 6-hour ramping events for all different generators. Especially generators with higher ramp rates like gas and oil turbine and internal combustion engine generators increased their ramping events by 200% - 280%. For other generator types, including gas combined cycle generators, coal steam turbine generators, and gas and oil steam turbine generators, more and higher ramping events occurred as well for higher solar power penetration levels.