PhD Defence by Viktor Stepaniuk
07.02.2022 kl. 13.00 - 16.00
Viktor Stepaniuk, AAU Energy, will defend the thesis "Energy Management Systems for Smart Active Residential Buildings"
Energy Management Systems for Smart Active Residential Buildings
Associate Professor Jayakrishnan Pillai
Professor Birgitte Bak-Jensen
Associate Professor Erik Schaltz
Associate Professor Erik Schaltz, Aalborg University, Denmark (Chairman)
Professor Johan Driesen, KU Leuven, Belgium
Professor Mohan Kohle, University of Adger, Norway
The intention to counteract the climatic changes that our planet is experiencing as a result of human activity has brought a number of green initiatives to the existing traditional energy systems. However, increasing integration of more intermittent Renewable Energy Sources (RESs) into the power grid and the growing electrification of heating and transport sectors, induces a number of operational challenges that are currently faced by system operators in many countries. Limited power output forecasting accuracy of RESs (caused by abrupt changes in weather conditions) and difficulties with foreseeing electricity demand for flexible loads, as well as power generations on the low-voltage 0.4kV level of the power grid, lead to grid congestion issues, reverse power flow, and needs for reinforcement of grid infrastructure. All this radically changes not only the power system structures (that have been vertically integrated previously) but also the mechanisms of interactions between various parties/entities, as well as the management and control schemes.
One of the most promising solutions to address these challenges and to postpone very costly grid reinforcement as of today is found in the utilisation of energy flexibility on the demand side (that is shifting from supply control to demand control). Buildings, in this respect, being the largest energy consumption sector globally, is that particular resource of energy flexibility that receive one of the greatest emphasis today. The emergence of individual local RES generations, heat pumps, electric vehicles, as well as the automation of various indoor processes, in this connection, makes buildings the most attractive platform for introducing new technologies and "smarter" solutions that will enable utilisation of this flexibility in fundamentally new way. Nonetheless, the emergence of new components, as well as the transition to a market-based energy system structure, requires also new schemes for active interaction between these energy-flexible loads and various market participants. Existing demand response schemes were mostly applicable to large industrial or commercial customers and far not always available for such consumers as an average household. Furthermore, in many schemes the fact of market relationships is not taken into account. In addition, a unique generally accepted scheme/methodology for calculating such flexibility that would serve as the basis for both proactive power system operation planning and for financial calculations simply does not exist today.
This dissertation first provides a more detailed overview of the existing problems in power systems, and an overview of market mechanisms for planning, purchasing and selling electricity on the example of Denmark. The importance and complexity of providing ancillary services for balancing generation and demand, which is getting more complicated every year due to uncertainties caused by the growth of RESs and flexible loads are highlighted. It is described in detail, what actually energy flexibility is, provides an overview of types, resources, existing mechanisms and rules, as well as an overview of various authors works describing the provision of such energy-flexible services. The difficulties with the delivering these services are emphasised from small consumers and the actual lack of schemes, regulations, market mechanisms for interaction between various market players, as well as the actual absence of market platforms where these services can be freely procured today. The importance of estimating the flexibility potential and quantifying the exact amount of energy flexibility in kilowatt-hours (i.e. the amount of peak energy shaved or shifted during active service provision) are discussed. The relevance of detailed modelling of energy-flexible loads for determining the above indices is also emphasized.
At the next stage of the study, models of various household energy system components, such as photovoltaic (PV) panels, micro wind turbine (WT), battery, heat pump (HP) and a hot water storage tank (HWST) were created. Particular attention is paid to the HP and HWST (referred to here as heat pump system (HPS)), as these components are considered as the main resource of energy flexibility in this thesis. The degree of flexibility that can be provided by a heat pump depends largely on the specifics of its operation that includes conversion and restart delays, defrost mode and guaranteed power-on time. Also, it depends on the amount of thermal energy controlled in the tank and its energy state. In order to maximally reflect the HPS operational behaviour and its details model is developed.
Having created models of individual components, the impact of main active components on the household's needs of electricity supplied from the grid was simulated and studied in detail. This has been done by combining different scenarios of these components under a single coordination algorithm. After examining the impact of upgrading the energy systems of a single building, the next step was to investigate the impact of an aggregated group of such buildings. To do so, 25 models of similar smart active residential buildings were created using previously created models of separate components and historically measured base electrical and thermal load data for 25 households. This allowed to analyse energy consumption, as well as to investigate the impact of such modernization of the energy systems of buildings on the voltage deviation of the feeder line that supplies these houses.
To calculate the energy flexibility potential, a rule-based management strategy for responding to demand response signal, and its creation has been developed.
The final stage is the investigation of how the aggregated flexibility of 25 active houses connected to a single feeder can help to address the voltage drop issues occurring in that feeder. For this reason, another centralized coordinating control strategy was designed. The main feature of the proposed strategy is that the thermal comfort of the residents is always the primary priority and thereafter responses to request signals are provided. While the application of this strategy showed the ability to solve 81% of voltage drop periods occurring in that feeder during ordinary operation, applying the worst-case scenario. This confirms that the use of the proposed strategies can be mutually beneficial, both for system operators (in terms of voltage regulation support), and for household owners who will receive incentive payments for activating demand response.
THE DEFENCE will be IN ENGLISH - all are welcome.