Toward optimal operation of multienergy home-microgrids for power balancing in distribution networks: a model predictive control approach

The energy policy objectives of the German government regarding renewable energy sources and energy efficiency will lead to a significantly increase in the share of photovoltaics, storage systems, CHP plants, and heat pumps, especially at the distribution grid level. In the future, inside a household, such systems must be coordinated in such a way that they can respond to variable network conditions as a single flexible unit. This dissertation defines home-microgrid as a residential building with integrated distributed energy resources, and follows a bottom-up approach, based on the cellular approach, which aims at improving local balancing in low-voltage grids by using the flexibilities of home-microgrids. For this purpose, the dissertation develops optimization-based strategies for the coordination of multienergy home-microgrids, focusing on the use of model predictive control. The main core of the work is the formulation of the underlying optimization problems and the investigation of coordination strategies for interconnected home-microgrids. In this context, the work presents the use of the dual decomposition and the alternating direction method of multipliers for hierarchical-distributed coordination strategies. Finally, this dissertation introduces a framework for the co-simulation of electrical networks with penetration of multienergy home-microgrids

Using Open Data for Modeling and Simulation of the All Electrical Society in eASiMOV

The present study examines a future energy systems scenario, the so-called All Electrical Society (AES), which is defined by a very high number of active prosumers in the distribution grid in view of future 100% renewables-based energy systems. In this paper, we present data modeling methods that describe the power consumption behavior and power generation patterns via time series for 78 prosumers, each fully equipped with rooftop PV, two battery electrical vehicles and a heat pump. Quasi-dynamic simulations of a low voltage grid under stress conditions are performed using open data and free software. The simulatively determined increase in network utilization and congestion is also compared with the currently available grid capacity gained through extensive measurements in the examined distribution grid. The result is that in the AES scenario the current deployed electrical infrastructure of the distribution grid will be more than heavily overloaded, both the transformers and the respective power lines

Modelling of an Intelligent Microgrid System in a Smart Grid Network

To achieve the goal of decarbonising the electric grid by 2050 and empowering energy citizen, this research focuses on the development of Microgrid (μGrid) systems in Irish environment. As part of the research work, an energy efficient and cost effective solution for μGrid, termed Community-μGrid (C-μGrid) is proposed. Here the users can modify their micro-Generation (μGen) converters to facilitate a single inverter in a C-μGrid structure. The new system could allow: (i) technological advantage of improved Power Quality (PQ); (ii) economic advantage of reduced cost of energy (COE) to achieve sustainability. Analysis of scenarios of C-μGrid (AC) systems is performed for a virtual community in Dublin, Ireland. It consists of (10 to 50) similar type of residential houses and assumes that each house has a wind-based μGen system. It is found that, compared to individual off-grid μGen systems, an off-grid C-μGrid can reduce upto 35% of energy storage capacity. Thus it helps to reduce the COE from €0.22/kWh to 0.16/kWh. In grid connected mode, it can sell excess energy to the grid and thus COE further decreases to €0.11/kWh. Thus a cost-effective C-μGrid is achieved. The proposed system can advance its energy management efficiency through implementation of Demand Side Management (DSM) technique. For the test case, 50% of energy storage capacity could be avoided through DSM technique. It also helps to further decrease the COE by 25%. The C-μGrid system with storage is optimised by implementing the Economic Model Predictive Control (EMPC) approach operating at the pricing level. Emphasis is given to the operational constraints related to the battery lifetime, so that the maintenance and replacement cost would be reduced. This technique could help to improve the battery performance with optimised storage and also reduces the COE of the system by 25%

Optimization approaches for exploiting the load flexibility of electric heating devices in smart grids

Energy systems all over the world are undergoing a fundamental transition to tackle climate change and other environmental challenges. The share of electricity generated by renewable energy sources has been steadily increasing. In order to cope with the intermittent nature of renewable energy sources, like photovoltaic systems and wind turbines, the electrical demand has to be adjusted to their power generation. To this end, flexible electrical loads are necessary. Moreover, optimization approaches and advanced information and communication technology can help to transform the traditional electricity grid into a smart grid. To shift the electricity consumption in time, electric heating devices, such as heat pumps or electric water heaters, provide significant flexibility. In order to exploit this flexibility, optimization approaches for controlling flexible devices are essential. Most studies in the literature use centralized optimization or uncoordinated decentralized optimization. Centralized optimization has crucial drawbacks regarding computational complexity, privacy, and robustness, but uncoordinated decentralized optimization leads to suboptimal results. In this thesis, coordinated decentralized and hybrid optimization approaches with low computational requirements are developed for exploiting the flexibility of electric heating devices. An essential feature of all developed methods is that they preserve the privacy of the residents. This cumulative thesis comprises four papers that introduce different types of optimization approaches. In Paper A, rule-based heuristic control algorithms for modulating electric heating devices are developed that minimize the heating costs of a residential area. Moreover, control algorithms for minimizing surplus energy that otherwise could be curtailed are introduced. They increase the self-consumption rate of locally generated electricity from photovoltaics. The heuristic control algorithms use a privacy-preserving control and communication architecture that combines centralized and decentralized control approaches. Compared to a conventional control strategy, the results of simulations show cost reductions of between 4.1% and 13.3% and reductions of between 38.3% and 52.6% regarding the surplus energy. Paper B introduces two novel coordinating decentralized optimization approaches for scheduling-based optimization. A comparison with different decentralized optimization approaches from the literature shows that the developed methods, on average, lead to 10% less surplus energy. Further, an optimization procedure is defined that generates a diverse solution pool for the problem of maximizing the self-consumption rate of locally generated renewable energy. This solution pool is needed for the coordination mechanisms of several decentralized optimization approaches. Combining the decentralized optimization approaches with the defined procedure to generate diverse solution pools, on average, leads to 100 kWh (16.5%) less surplus energy per day for a simulated residential area with 90 buildings. In Paper C, another decentralized optimization approach that aims to minimize surplus energy and reduce the peak load in a local grid is developed. Moreover, two methods that distribute a central wind power profile to the different buildings of a residential area are introduced. Compared to the approaches from the literature, the novel decentralized optimization approach leads to improvements of between 0.8% and 13.3% regarding the surplus energy and the peak load. Paper D introduces uncertainty handling control algorithms for modulating electricheating devices. The algorithms can help centralized and decentralized scheduling-based optimization approaches to react to erroneous predictions of demand and generation. The analysis shows that the developed methods avoid violations of the residents\u27 comfort limits and increase the self-consumption rate of electricity generated by photovoltaic systems. All introduced optimization approaches yield a good trade-off between runtime and the quality of the results. Further, they respect the privacy of residents, lead to better utilization of renewable energy, and stabilize the grid. Hence, the developed optimization approaches can help future energy systems to cope with the high share of intermittent renewable energy sources

A Survey of Smart Energy Services for Private Households

The energy sector is challenged by the ongoing digitalization with emerging smart energy products and services. Smart energy products such as smart meters leverage innovative smart energy services promising both new business opportunities and values for customers. Smart products and services could enhance energy efficiency as well as enable private households to produce their own energy. Although services are regarded as a bridge to the customer, research on smart energy services is scarce. To address the gap, we assess smart energy services discussed in research and in the German consumer market and compare the findings from literature with the real market. Our survey provides researchers and practitioners with an overview of smart energy services and can serve as a starting point for service design, which in turn can support the diffusion of energy saving technologies

A Comprehensive Method For Coordinating Distributed Energy Resources In A Power Distribution System

Utilities, faced with increasingly limited resources, strive to maintain high levels of reliability in energy delivery by adopting improved methodologies in planning, operation, construction and maintenance. On the other hand, driven by steady research and development and increase in sales volume, the cost of deploying PV systems has been in constant decline since their first introduction to the market. The increased level of penetration of distributed energy resources in power distribution infrastructure presents various benefits such as loss reduction, resilience against cascading failures and access to more diversified resources. However, serious challenges and risks must be addressed to ensure continuity and reliability of service. By integrating necessary communication and control infrastructure into the distribution system, to develop a practically coordinated system of distributed resources, controllable load/generation centers will be developed which provide substantial flexibility for the operation of the distribution system. On the other hand, such a complex distributed system is prone to instability and black outs due to lack of a major infinite supply and other unpredicted variations in load and generation, which must be addressed. To devise a comprehensive method for coordination between Distributed Energy Resources in order to achieve a collective goal, is the key point to provide a fully functional and reliable power distribution system incorporating distributed energy resources. A road map to develop such comprehensive coordination system is explained and supporting scenarios and their associated simulation results are then elaborated. The proposed road map describes necessary steps to build a comprehensive solution for coordination between multiple agents in a microgrid or distribution feeder.\u2

The role of residential photovoltaic-coupled battery storages in the energy system from a regional perspective

The electric energy systems face a fundamental transformation triggered by the tackling of climate change, the long-term depletion of fossil fuels and the cost-decrease of renewable technologies. Especially photovoltaic (PV) energy installed on rooftops has become a major driver of the current energy transition. Residential buildings are often additionally equipped with battery storages raising the self-consumption of PV energy by the balancing of load and production. The increasing decentralization of the energy generation systems represents a challenge for the grid infrastructure, which has not been dimensioned for the feed-in on low voltage level in the past. This dissertation assesses the impact of residential PV-coupled battery storages on the energy systems from a regional perspective under consideration of the great multitude and heterogeneity of the systems. The divergence arises from the differences in equipment, PV sizes, battery capacities, efficiencies and consumption loads, but also from locally varying meteorological conditions. For reproducing this spatial variance, the raster-based land surface processes model Processes of radiation, mass and energy transfer (PROMET) is extended by a residential consumption, a PV and a battery storage component. This allows a physically based simulation of the energy flows considering the individual parameterization of the residential buildings and their spatiotemporal dependencies. The application of this model approach shows that the choice of the battery charging has a crucial influence on the regional integration of rooftop PV but also on the increase of PV self-consumption. The utilization of daily, dynamic feed-in limitations yields the highest reduction of residual loads while also maximizing self-consumption. The application of this charging strategy should be supported especially for larger PV and battery storage systems in order to reduce grid impacts. Apart from the battery management, the PV and battery expansion plays an essential role for their grid integration on regional scale. The diversity of residential energy systems offers further balancing potential due to the spatial variance in their residual loads. The highest regional grid-balancing is obtained when 30% of the buildings is equipped with PV systems. In this case, the additional utilization of battery storages reduces this effect to the benefit of higher self-consumption rates and therefore does not contribute to the reduction of grid excesses. This is different for high PV installation rates, as grid balancing diminishes. For this reason, financial support for batteries should be adjusted to the regional PV installation rates. Apart from the management strategies and expansion rates, the climatological and consumption-related boundary conditions have crucial impact on residential batteries and their potentials for increasing self-consumption and grid-relief. Both factors will undergo significant changes in the future. Scenarios until 2040 project that climate change affects the battery utilization in winter, whereas the effects of efficiency enhancement of domestic appliances dominates in the summer. The resulting increase in PV excesses could rise grid stresses further. In order to reduce potential losses, these developments should be considered in the dimensioning of batteries. The results show that the spatial variance between residential energy systems has a crucial impact on PV-coupled battery storages on regional scale. The developed approach, which is based on the extended utilization of a land surface processes model, offers the possibility to simulate the interactions between the residential energy flows for a multitude of buildings and to map regionally adjusted strategies for the integration of PV systems.Die elektrischen Energiesysteme stehen vor einem grundlegenden Wandel, der durch den Kampf gegen den Klimawandel, die langfristige Erschöpfung fossiler Brennstoffe und fallende Kosten für regenerative Technologien eingeleitet wird. Insbesondere die gebäudegebundene Photovoltaik (PV) Technologie hat sich zu einem der Haupttreiber der Energiewende entwickelt. Häufig werden in Wohngebäuden neben PV Systemen zusätzliche Batteriespeicher zum Schwankungsausgleich von Produktion und Verbrauch installiert, um den Eigenverbrauch der selbsterzeugten PV Energie zu erhöhen. Die steigende Dezentralisierung der Energieproduktion stellt jedoch eine Herausforderung für die Netzinfratruktur dar, die nicht für die Einspeisung auf Niederspannungsebene ausgelegt ist. Diese Dissertation untersucht die Auswirkungen von PV-gekoppelten Batteriespeichern von Wohngebäuden aus einer regionalen Perspektive. Hierbei muss die Vielzahl der Anlagen mit unterschiedlichen Ausprägungen der einzelnen Systeme berücksichtigt werden. Diese entstehen durch unterschiedliche Ausstattungen, Anlagengrößen, Batteriespeicherkapazitäten, Wirkungsgrade und Verbrauchsraten sowie den standortabhängigen, klimatologischen Bedingungen. Um diese räumliche Varianz abzubilden wurde das rasterbasierte Landoberflächenprozessmodell PROMET um ein Wohngebäudemodell mit Verbrauchs-, PV- und Batteriekomponente erweitert. Auf diese Weise können die Energieflüsse simuliert werden bei individueller Parametrisierung der Gebäudeenergiesysteme und ihrer raumzeitlichen Einflüsse. Mithilfe dieses Modells wurde festgestellt, dass die Wahl der Batterieladestrategie einen wesentlichen Einfluss auf die regionale Integration von PV Dachanlagen und die Erhöhung des Eigenverbrauchs hat. Variable PV-Einspeiselimits auf täglicher Basis führen hierbei zur höchsten Netzlast-Reduzierung bei gleichzeitiger Maximierung des Eigenverbrauchs. Die Nutzung dieser Ladestrategie sollte insbesondere für große Anlagen unterstützt werden, um die Netzauswirkungen zu reduzieren. Auch die PV und Batterieausbaurate spielt auf regionaler Ebene eine wesentliche Rolle für deren Integration, denn die Diversität der Gebäudeenergiesysteme bietet ein zusätzliches Ausgleichspotential der Überschüsse aufgrund der räumlichen Varianz der Residuallasten. Der höchste Netzausgleich der Residuallasten von Wohngebäuden ergibt sich, wenn 30% eine PV Anlage besitzen. Bei dieser Ausbaurate tragen Batteriespeicher kaum zu einer Abnahme von Netzüberschüssen bei, da sie den räumlichen Ausgleich zugunsten höherer Eigenverbrauchsraten verringern. Bei hohen PV-Ausbauraten jedoch spielt der Netzausgleich keine Rolle mehr, sodass der Einsatz von Batterien einen wichtigen Anteil zur Integration von PV-Anlagen übernimmt. Aus diesem Grund empfiehlt es sich, die Förderstrukturen für Batteriespeicher an die regionalen PV Ausbauraten anzupassen. Neben Ladestrategien und Ausbaugraden wirken sich auch die klimatologischen und verbrauchsbezogenen Rahmenbedingungen auf die Batteriespeicher aus, die sich in den nächsten Jahrzehnten stark verändern werden. Szenarien bis 2040 sagen vorher, dass sich der Klimawandel im Winter und Effizienzsteigerungen von Haushaltsgeräten im Sommer auf die Nutzung der Batterien auswirken. Steigende PV Überschüsse könnten die Netze in den Sommermonaten zukünftig verstärkt belasten. Diese Entwicklungen sollten auch bei der Dimensionierung der Batteriespeicherkapazitäten berücksichtigt werden, um potenzielle Verluste zu mindern. Die Ergebnisse zeigen, dass die kleinräumige Varianz der Gebäudeenergiesysteme auf regionaler Ebene einen großen Einfluss auf PV-gekoppelten Batteriespeichern haben. Der in dieser Arbeit entwickelte Ansatz, der auf der erweiterten Anwendung eines Landoberflächenprozessmodells basiert, bietet die Möglichkeit, auch die raumzeitlichen Wechselwirkungen zwischen den Energieflüssen für eine Vielzahl von Wohngebäuden zu erfassen und damit Strategien für die Integration von PV Systemen an regionale Gegebenheiten anzupassen

The role of residential photovoltaic-coupled battery storages in the energy system from a regional perspective

The electric energy systems face a fundamental transformation triggered by the tackling of climate change, the long-term depletion of fossil fuels and the cost-decrease of renewable technologies. Especially photovoltaic (PV) energy installed on rooftops has become a major driver of the current energy transition. Residential buildings are often additionally equipped with battery storages raising the self-consumption of PV energy by the balancing of load and production. The increasing decentralization of the energy generation systems represents a challenge for the grid infrastructure, which has not been dimensioned for the feed-in on low voltage level in the past. This dissertation assesses the impact of residential PV-coupled battery storages on the energy systems from a regional perspective under consideration of the great multitude and heterogeneity of the systems. The divergence arises from the differences in equipment, PV sizes, battery capacities, efficiencies and consumption loads, but also from locally varying meteorological conditions. For reproducing this spatial variance, the raster-based land surface processes model Processes of radiation, mass and energy transfer (PROMET) is extended by a residential consumption, a PV and a battery storage component. This allows a physically based simulation of the energy flows considering the individual parameterization of the residential buildings and their spatiotemporal dependencies. The application of this model approach shows that the choice of the battery charging has a crucial influence on the regional integration of rooftop PV but also on the increase of PV self-consumption. The utilization of daily, dynamic feed-in limitations yields the highest reduction of residual loads while also maximizing self-consumption. The application of this charging strategy should be supported especially for larger PV and battery storage systems in order to reduce grid impacts. Apart from the battery management, the PV and battery expansion plays an essential role for their grid integration on regional scale. The diversity of residential energy systems offers further balancing potential due to the spatial variance in their residual loads. The highest regional grid-balancing is obtained when 30% of the buildings is equipped with PV systems. In this case, the additional utilization of battery storages reduces this effect to the benefit of higher self-consumption rates and therefore does not contribute to the reduction of grid excesses. This is different for high PV installation rates, as grid balancing diminishes. For this reason, financial support for batteries should be adjusted to the regional PV installation rates. Apart from the management strategies and expansion rates, the climatological and consumption-related boundary conditions have crucial impact on residential batteries and their potentials for increasing self-consumption and grid-relief. Both factors will undergo significant changes in the future. Scenarios until 2040 project that climate change affects the battery utilization in winter, whereas the effects of efficiency enhancement of domestic appliances dominates in the summer. The resulting increase in PV excesses could rise grid stresses further. In order to reduce potential losses, these developments should be considered in the dimensioning of batteries. The results show that the spatial variance between residential energy systems has a crucial impact on PV-coupled battery storages on regional scale. The developed approach, which is based on the extended utilization of a land surface processes model, offers the possibility to simulate the interactions between the residential energy flows for a multitude of buildings and to map regionally adjusted strategies for the integration of PV systems.Die elektrischen Energiesysteme stehen vor einem grundlegenden Wandel, der durch den Kampf gegen den Klimawandel, die langfristige Erschöpfung fossiler Brennstoffe und fallende Kosten für regenerative Technologien eingeleitet wird. Insbesondere die gebäudegebundene Photovoltaik (PV) Technologie hat sich zu einem der Haupttreiber der Energiewende entwickelt. Häufig werden in Wohngebäuden neben PV Systemen zusätzliche Batteriespeicher zum Schwankungsausgleich von Produktion und Verbrauch installiert, um den Eigenverbrauch der selbsterzeugten PV Energie zu erhöhen. Die steigende Dezentralisierung der Energieproduktion stellt jedoch eine Herausforderung für die Netzinfratruktur dar, die nicht für die Einspeisung auf Niederspannungsebene ausgelegt ist. Diese Dissertation untersucht die Auswirkungen von PV-gekoppelten Batteriespeichern von Wohngebäuden aus einer regionalen Perspektive. Hierbei muss die Vielzahl der Anlagen mit unterschiedlichen Ausprägungen der einzelnen Systeme berücksichtigt werden. Diese entstehen durch unterschiedliche Ausstattungen, Anlagengrößen, Batteriespeicherkapazitäten, Wirkungsgrade und Verbrauchsraten sowie den standortabhängigen, klimatologischen Bedingungen. Um diese räumliche Varianz abzubilden wurde das rasterbasierte Landoberflächenprozessmodell PROMET um ein Wohngebäudemodell mit Verbrauchs-, PV- und Batteriekomponente erweitert. Auf diese Weise können die Energieflüsse simuliert werden bei individueller Parametrisierung der Gebäudeenergiesysteme und ihrer raumzeitlichen Einflüsse. Mithilfe dieses Modells wurde festgestellt, dass die Wahl der Batterieladestrategie einen wesentlichen Einfluss auf die regionale Integration von PV Dachanlagen und die Erhöhung des Eigenverbrauchs hat. Variable PV-Einspeiselimits auf täglicher Basis führen hierbei zur höchsten Netzlast-Reduzierung bei gleichzeitiger Maximierung des Eigenverbrauchs. Die Nutzung dieser Ladestrategie sollte insbesondere für große Anlagen unterstützt werden, um die Netzauswirkungen zu reduzieren. Auch die PV und Batterieausbaurate spielt auf regionaler Ebene eine wesentliche Rolle für deren Integration, denn die Diversität der Gebäudeenergiesysteme bietet ein zusätzliches Ausgleichspotential der Überschüsse aufgrund der räumlichen Varianz der Residuallasten. Der höchste Netzausgleich der Residuallasten von Wohngebäuden ergibt sich, wenn 30% eine PV Anlage besitzen. Bei dieser Ausbaurate tragen Batteriespeicher kaum zu einer Abnahme von Netzüberschüssen bei, da sie den räumlichen Ausgleich zugunsten höherer Eigenverbrauchsraten verringern. Bei hohen PV-Ausbauraten jedoch spielt der Netzausgleich keine Rolle mehr, sodass der Einsatz von Batterien einen wichtigen Anteil zur Integration von PV-Anlagen übernimmt. Aus diesem Grund empfiehlt es sich, die Förderstrukturen für Batteriespeicher an die regionalen PV Ausbauraten anzupassen. Neben Ladestrategien und Ausbaugraden wirken sich auch die klimatologischen und verbrauchsbezogenen Rahmenbedingungen auf die Batteriespeicher aus, die sich in den nächsten Jahrzehnten stark verändern werden. Szenarien bis 2040 sagen vorher, dass sich der Klimawandel im Winter und Effizienzsteigerungen von Haushaltsgeräten im Sommer auf die Nutzung der Batterien auswirken. Steigende PV Überschüsse könnten die Netze in den Sommermonaten zukünftig verstärkt belasten. Diese Entwicklungen sollten auch bei der Dimensionierung der Batteriespeicherkapazitäten berücksichtigt werden, um potenzielle Verluste zu mindern. Die Ergebnisse zeigen, dass die kleinräumige Varianz der Gebäudeenergiesysteme auf regionaler Ebene einen großen Einfluss auf PV-gekoppelten Batteriespeichern haben. Der in dieser Arbeit entwickelte Ansatz, der auf der erweiterten Anwendung eines Landoberflächenprozessmodells basiert, bietet die Möglichkeit, auch die raumzeitlichen Wechselwirkungen zwischen den Energieflüssen für eine Vielzahl von Wohngebäuden zu erfassen und damit Strategien für die Integration von PV Systemen an regionale Gegebenheiten anzupassen