Improving hydropower operational models for high penetrations of variable generation in the Western United States
CADSWES: Timothy Magee, Mitch Clement, Edie Zagona
NREL: Eduardo Ibanez, Greg Brinkman, Michael Milligan
Increasing wind and solar penetration into the electric power system in the Western United States leads to increased demand for flexible resources to balance net load (load minus wind and solar). Hydropower generation is one option for a resource that already exists throughout much of the Western Interconnection and is physically capable of providing flexibility. However, multipurpose reservoirs must meet an ever growing, complex mix of power and nonpower objectives and constraints including ESA and other environmental objectives, navigation, flood control, water supply, and recreation among others. Generally, these objectives and constraints prevail over generation of electricity and prevent utilizing the full amount of the physical flexibility that hydropower can provide.
Studies such as NREL’s Western Wind and Solar Integration Study (WWSIS) to understand the costs and operating impacts of variable and uncertain renewals on the grid typically simplify assumptions about the availability and flexibility of hydropower. Conversely, studies that focus on hydropower system optimization typically omit detailed representation of the power system, thus cannot accurately value the hydropower objectives in the multi-objective solution. The mutual and dynamic feedback between these two complex systems is not captured, thus both system analyses are incomplete. The result is less than optimal operations of hydro systems and less than complete understanding of the true impacts of variable and uncertain renewables on the grid. This project will utilize the detailed hydro modeling system RiverWare, developed at CU Boulder, to optimize the operation of hydro power facilities taking into account all the objectives and constraints mentioned above, while maximizing their participation in the production of electricity and ancillary services as modeled by NREL into the power system production model PLEXOS. Based on this simulation, the researchers will be able to review the common assumptions used to model hydro in long-term electric planning and production cost studies and make recommendations that will benefit the integration of high penetration of renewable energy.
The proposed project will explore the potential contribution that a more accurate representation of hydropower could have to the electric system, specifically in the context of phase 2 of WWSIS. In order to do so, a representative hydropower project will be modeled by CU in RiverWare, using price data produced as output of PLEXOS in the WWSIS Phase 2. Comparing the optimized hydro production from RiverWare with the PLEXOS results, NREL and CU will analyze the potential impact that a better representation of the hydro modeling could have on the electric system.
We envision that the success of this project will lead to further collaboration and better integration of hydropower and the electric system. In the end, a better estimate of the flexibility contribution from existing hydro power plants to the electrical system could facilitate the integration of large penetration of renewables, reducing the need for more costly mitigation strategies. The results of this project would help the researchers seek more funds to achieve more ambitious objectives, making the JISEA funds an excellent fit for this project. One future endeavor would involve a tight integration of the two software platforms introduced in this proposal. PLEXOS and RiverWare are both designed with the idea of extending their capabilities so the researchers would like to be able to build a two-way communication mechanism between the two, extending the manual process in this proposal. This automatization would allow the modeling of more reservoirs in the Western Interconnection and other footprints and for more scenarios. The results of this study would suggest the possible value of this future work.
The researchers would also pursue the extrapolation of insights from the RiverWare hydro system model results in order to enhance the representation of hydro units in PLEXOS. These could also be extrapolated to other production cost or long-term planning models.