| Summary: | Hydroelectric generation has been well documented as a flexible and fast-responding resource, which can be quite complimentary to variable and uncertain renewable energy resources. However, hydropower is also a variable energy resource that is limited by river inflows and the live storage capacity of its reservoirs. The goal of this thesis is to explore the possible incremental value that curtailment of wind power might contribute, without reducing a wind power producer’s income, in a market context. Therefore, the ultimate use of this research is as a planning study.
The modeling in this research was performed at an hourly time resolution and only focused on real (not reactive), available wind power. An hydraulic simulation and electrical energy generation optimization model of a hydropower system, using a linear programming approach, was used. It was a deterministic model, so specific independent variables had to be manually manipulated. These variables were wind power installed capacity, hydrologic regime (wet, average, and dry), import/export transmission capacity, and cost of wind energy. The optimal objective function values of the model at the end of each yearly run were compared to each other.
The opportunity for economically beneficial curtailment came from market-based competition for the finite amounts of generation capacity, energy, and reservoir storage in the hydroelectric system. Existing flexibility in the large storage reservoirs was used by the model to shift the wind energy to export periods with the highest market prices. Temporal analysis of wind power curtailment showed that curtailed wind energy was concentrated in the light-load hours (10:00 PM to 6:00 AM) during the spring freshet (snowmelt) period. These were periods of low domestic electrical load, low market energy prices, high energy import levels, and high local river inflows. The total annual amount of curtailed wind energy was between 0.5% and 2%. Based on input parameters, including energy market and generation capacity market prices, intertie capacities, available wind energy, river inflows, and load, an optimal value of wind energy production was determined. Allowing wind power curtailment purely for economic reasons resulted in an incremental increase in this wind energy value between 1% and 4%.
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