Coordination and Control of Flexible Building Loads for Renewable Integration; Demonstrations using VOLTTRON

Abstract

Renewable energy resources such as wind and solar power have a high degree of uncertainty. Large-scale integration of these variable generation sources into the grid is a big challenge for power system operators. Buildings, in which we live and work, consume about 75% of the total electricity in the United States. They also have a large capacity of power flexibility due to their massive thermal capacitance. Therefore, they present a great opportunity to help the grid to manage power balance. In this report, we study coordination and control of flexible building loads for renewable integration. We first present the motivation and background, and conduct a literature review on building-to-grid integration. We also compile a catalog of flexible building loads that have great potential for renewable integration, and discuss their characteristics. We next collect solar generation data from a photovoltaic panel on Pacific Northwest National Laboratory campus, and conduct data analysis to study their characteristics. We find that solar generation output has a strong uncertainty, and the uncertainty occurs at almost all time scales. Additional data from other sources are also used to verify our study. We propose two transactive coordination strategies to manage flexible building loads for renewable integration. We prove the theories that support the two transactive coordination strategies and discuss their pros and cons. In this report, we select three types of flexible building loads-air-handling unit, rooftop unit, and a population of water heaters (WHs)-for which we demonstrate control of the flexible load to track a dispatch signal (e.g., renewable generation fluctuation) using experiment, simulation, or hardware-in-the-loop study. More specifically, we present the system description, model identification, controller design, test bed setup, and experiment results for each demonstration. We show that coordination and control of flexible loads has a great potential to integrate variable generation sources. The flexible loads can successfully track a power dispatch signal from the coordinator, while having little impact on the quality of service to the end-users. v Summary Decarbonizing the global energy system is one of the most important endeavors of our time. It is widely accepted that a sustainable energy future will increasingly rely on renewable energy sources such as wind and solar. However, these variable generations are volatile, intermittent, and uncontrollable. The vast integration of variable generation sources brings a significant amount of uncertainty to the power grid, and presents a daunting challenge to current power system operation and control. Maintaining the power balance with uncertain renewables is one of the most important problems in smart grid research. Traditionally, the uncertainty of renewables has been handled through supply-side (generation) reserves. However, recent studies show that deep penetration of renewables will substantially increase the procurement of additional backup generation...

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