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Efficient Grid Connected Buildings: A Distributed Control Framework for Managing Flexible Loads

Periodic Reporting for period 1 - BuildingControls (Efficient Grid Connected Buildings: A Distributed Control Framework for Managing Flexible Loads)

Reporting period: 2016-06-01 to 2018-05-31

The renewable energy penetration targets set by EU and US necessitate a radical change in the way we operate the electric power grid. Increased penetration of the intermittent and uncertain renewable energy sources effectively implies that additional load and generation flexibility is required at multiple time-scales to ensure safe and stable operation of the electric grid. Since conventional generation is increasingly displaced by renewables, this additional flexibility can no longer be sourced solely from conventional plants.
According to the International Energy Agency, buildings are responsible for about 40% of the global energy consumption, and about 50% of the energy used in a building is accounted for by the heating, ventilation and air conditioning (HVAC) system. Thus, improving operational efficiency of HVAC systems will results in large savings in the energy consumption. Moreover, buildings present a unique opportunity as flexible loads that can be controlled to provide ancillary services to the electric power grid, and thus enable high penetration of renewables. High thermal capacity of large commercial buildings allow real-time control of their HVAC systems to regulate electricity demand as required for grid stability, without effecting the quality of service in the building significantly.
Motivated by the shift in power system characteristics described above, BuildingControls project aims to achieve the following scientific objectives:
1) Development of optimal thermostatic control algorithms for efficient energy use and peak load reduction in buildings
2) Development of a distributed control framework to coordinate multiple buildings as flexible energy resources for ancillary services:
3) Assessment of the performance of the distributed control framework from economic, environmental and sustainability perspectives
Within the duration of the project, novel controls and optimization approaches and performance assessment methods are developed to address these objectives, and their viability are demonstrated in simulation and partially in real-life demo environments.
In the BuildingControls project, we developed control algorithms to operate building HVAC systems efficiently while sacrificing thermal comfort conditions. The designed controller was tested both on simulations as well as a real building in Izmir. The results show that our controller provides, on average, 16% and 18% savings in energy use for heating and cooling modes, respectively. The controller commands available zone thermostats, and avoids expensive hardware changes. Therefore, it is a low-cost solution implementable as a retrofit to existing buildings.

In addition to the HVAC control algorithms, within the scope of the BuildingControls project, we pursued distributed optimization algorithms to vary building electrical loads as a response to load reduction demands. This helps the power grid maintain stability in the case of system faults, high intermittency of renewables, generation failure, etc. When a demand response signal is received, our distributed algorithms assess the status of the building and the environment, and converge to a new optimal load distribution profile for hundreds of buildings using a fast and scalable algorithm. Simulation results suggest that the distributed controller is sufficiently fast (converges in 1.13s for a 1000 building case) in responding to demand response signals, and can reduce total load of the building fleet up to 30%.

The results of the BuildingControls project has been shared with the scientific community through several journal/conference publications and workshop participations. In addition, the researcher reached out to the general public via various high school visits, a workshop for high school students, articles in newspapers, and a talk on MSCA Researchers' Night Event coordinated by the host institution. Within the project, a 3-day workshop on exergy and its applications was organized in August, 2018. This workshop brought together experts from exergy and controls fields as well as practitioners and graduate students from many engineering disciplines, and it created a venue to pursue common research opportunities.

In addition to the scientific research, the project pursued exploitation acitivities with several local companies, and applied to two SME project grants to the “Scientific and Technological Research Council of Turkey (TUBITAK)”, one for the development of a demand response program in Northwestern Turkey, and another one on implementation of the optimal control algorithms for residential energy management systems. The commercial potential of the project results were acknowledged by the industrial advisory board of the host institution. An international patent application on “integrated building operation, design and optimization method” has been filed with PCT. The thermostatic HVAC control method developed in the project is at the core of this patent application.
The BuildingControls project addresses issues related to climate change or the environment mainly in two ways: (1) efficient use of building HVAC equipment, without significant degradation in comfort, will reduce primary energy utilization (2) effective management of flexible building loads in ancillary services will enable higher penetration of renewable energy sources in the power grid, and hence will reduce dependency on carbon emitting fossil fuels.
The project is well aligned with the EU Horizon 2020 objective of improved operational reliability and efficiency of the power grid. It enables higher penetration of renewable sources, eventually resulting in reduction of energy-related emissions and improvement in overall energy efficiency. Improving energy efficiency of buildings has important macro-economic benefits and can substantially contribute to all three priorities of the Europe 2020 Strategy, as well as to the EU 2050 roadmap targets. Flexible controllable loads are considered essential in providing the frequency control in the power grid. Buildings today are limited by existing controls systems that can’t easily participate in ancillary services at the speed or scale that is required by the grid. The control framework proposed in this project addresses these challenges, and aims to provide a control solution that is fast, scalable, and energy-efficient.