Cellular energy system
The cellular energy system or the cellular approach is a new organizational model for energy supply . This interdisciplinary model takes technical, economic, legal and political (and social) issues into account. In the cellular energy system, according to the principle of subsidiarity, the physical balance between energy supply and demand is established as far as possible on a regional, local level. An energy cell consists of the infrastructure for various forms of energy , in which the balancing of generation and consumption across all existing forms of energy is organized through energy cell management in possible coordination with neighboring cells . The central component of this model is the energy cell.
Regardless of how the demand for final energy will develop in the future, it will be essential for energy transport and storage to include other energy sources. In contrast to gas and heat, supply and demand for electrical energy must be balanced at all times. With the increasing volatility of generation based on renewable energies , the balancing requirements for electrical energy grow, which have to be met by including the storage capacity of gas and heat or the time-controlled use of charging infrastructures.
definition
An energy cell consists of the infrastructure for various forms of energy, in which the balancing of generation and consumption across all existing forms of energy is organized through energy cell management in possible coordination with neighboring cells.
- For infrastructure , all resources are counted, which are used for the conversion of energy to their transport and distribution, as well as for storage.
- The forms of energy considered include u. a. Electricity, gas, heat and mobility. A cell can contain only one form of energy.
- The energy cell management (EZM) includes all equipment of the control technology including the necessary communication technology
- Neighboring cells can be arranged hierarchically. There are therefore cells on the same level as well as on superimposed and subordinate levels.
- In the case of balancing , which can be carried out both seasonally or dynamically, three states can arise: balanced, oversupplied or undersupplied via all forms of energy available. The energy cells are used to build the energy system. The structure is repeated on all network levels.
Origin and model
motivation
The generation of energy from renewable sources poses special challenges. This applies in particular to the need to make the system more flexible in the electricity , heat , gas and energy sources for mobility in order to manage the volatility of generation. Linked to this are the increase in the diversity of active actors and the degree of networking, but also the emergence of new forms of organization between the actors (e.g. sharing, virtual power plants). As a result, the complexity of the system management increases.
Are means of mastering complexity
- the design of interoperability (language, models, methodology),
- Digitization as the basis of mass capability,
- Decomposition into autonomous and connected systems as well
- Reliability, information security and data protection in the field of digitization
The diversity results from the applicability of renewable generation in the most varied of scales from buildings, through city quarters and areas, through localities, cities to regions, to national and international structures. The growing complexity can lead to the uncontrollability of the entire system if the central control is continued. But the autonomy of diverse and connected subsystems without rules of interaction can also lead to chaotic behavior. The art of a stable and at the same time flexible and developable system is to act locally as an independent system, but at the same time to develop the synergies of a global network.
It is therefore the set of mechanisms to be developed within subsystems that enable autonomy, which are implemented by energy management systems within the subsystems - the energy cells. However, the rules at the boundaries between the subsystems, which enable a flexible overall system as a type of self-optimizing energy organism, must also be designed. The previously centrally controlled overall system is thus being transformed into a system of coevolving subsystems with shared control responsibility, the cellular energy system .
history
With the accelerated expansion of renewable energies in the first decade of the 21st century, awareness of the challenges arising due to increasing complexity matured - first in Europe, but then also in the USA and Asia, for example in China and Japan. The source of the investigations was research and development around the terms smart grid and microgrid .
On the basis of the E-Energy funding program, research and development on these topics in particular could be intensified in Germany. In particular, the proposal for the cellular approach in the energy system was formulated for the first time in this context, whereby a model was introduced in. The further investigation of application scenarios of this model was made possible with the specification of the demonstration project C / sells in. The study calculated network measures based on the cellular approach. The study compares and optimizes centrally and decentrally oriented expansion paths to a power supply from renewable energies in Germany. As part of the VDE studies on the cellular approach [VDE, 2015, The cellular approach] and [VDE, 2019, Cellular Energy System], the Association of Electrical, Electronic and Information Technologies (VDE) transferred the concept to a broad discussion process among experts.
In order to enable communication in this process on the basis of a common language, both a system model for describing the overall system and the composition of subsystems and a flexibility model are required. With the help of the flexibility model, the rules at the limits of the subsystems described by the system model are to be defined. In order to promote the agreement of corresponding models, the working group "Terminology Smart Energy" at the DKE published a publicly available specification under the same title in the first draft.
System model
Based on the concept of the system, the energy system becomes the entirety of interrelated objects in the form of components that can be seen as a whole in the context of energy generation, storage, use, and transport and can be viewed as separate from their environment, whereby the interaction with the environment takes place via interfaces. The state of the system changes through the interactions with the environment. In the broader context when considering energy systems, the quantities energy and information in particular are considered as attributes of a cybernetic system that change over time and that are exchanged between the system and the system environment using the interfaces.
On this basis, an energy system can be defined in the smallest spatial extent, for example within a building. For this purpose, the energy-related components from extraction to use, including storage and transport, as well as the IT components for monitoring , management and control of energy flows and the interfaces for exchanging energy and information with the system environment are required. A corresponding model with an attribute system description based on the components as attributes of the zeroth level and the functions, properties and relationships as attributes of the first level was introduced in.
If two or more of these energy systems with the same attributes are connected to one another via interfaces, an energy system network is created as a system aggregate . Modern energy systems are increasingly being managed using information processing components in order to meet the challenges of renewable, fluctuating and decentralized energy generation with energy generation right down to the properties in the low-voltage range. The term intelligent energy system (Smart Energy System) was coined for this connection between energy and information infrastructure.
To implement an intelligent energy system on the one hand as an autonomous system and at the same time as part of a connected structure, the term energy cell is introduced for this entity . If several energy cells are now connected to one another through interfaces in an embedding structure, with at least one new, common component (attribute) being created, a system of systems is created . For example, an energy management system for a city district aggregates all energy flows beyond the building's management systems. On this basis, an energy system arises from the integration of energy systems, which thus form cells of an overall network - energy organism as an analogy. The term cellular energy system is defined for this structure of individual energy cells.
Finally, cells can be typed in the following way. The expression can be as closed, private cells or as closed distribution and local networks, for example as
- Residential & commercial buildings,
- Neighborhoods (areas within a municipality potentially as a micro-grid)
- Industrial and commercial areas (potentially operated as a micro-grid)
or as public network cells like
- Distribution networks and other local networks
- Transmission networks and other long-distance networks
- Network in Europe
respectively.
These cells interact in two dimensions as physical, energetically directly coupled cells, horizontally with cells of the same type (residential building to residential building, district to district, distribution network to distribution network, etc.) as well as vertically with cells of other types (residential building with district, district with distribution network, distribution network with transmission network, etc.). However, virtual, information technology-connected, market cells can also be developed , the energetic coupling of which to other cells takes place indirectly via other cells, for areas of action such as regional markets, energy communities or virtual power plants.
concept
While with a centralized generation of electrical energy this is only transported from higher to lower voltage levels, with the decentralized generation an energy transport takes place in the opposite direction. The original planning of the German electrical supply system was based on the premise of a system with unidirectional energy transport. A stable power supply requires a balance between generation and consumption at all times. Of course, this also applies to the power supply within a cell or within a cellular energy system. As a result, fluctuating electricity requirements must also be balanced there by using controllable electricity generators or by specifically switching consumers on and off. The figure on the right shows schematically which components are required to integrate a cellular energy system into the existing infrastructures of electricity, gas and heating networks.
Sector coupling
The term sector coupling is generally understood to mean the energy-technical and energy-economical connection of electricity, heat, gas and energy carriers for mobility and industrial processes. In more general terms, it can include all technologies and processes with which different types of energy can be exchanged with one another or the overall energy consumption can be optimized by shifting between forms of energy. The current drivers of sector coupling are heat pumps ( power-to-heat ) and electric vehicles (power-to-mobility) [12]. There are also other power-to-X technologies such as power-to-gas , power-to-liquid and power-to-chemicals .
Planning the energy cells
The independent planning of the electricity, gas and heating sectors leads to a suboptimal overall design of the energy infrastructure. The power grid is expected to be pushed to its limits more and more by renewable energies, electromobility and the increasing number of heat pumps and CHP systems. The gas network, on the other hand, does not experience these extreme changes. The networks are designed according to worst-case situations [7]. For battery storage systems, power-to-gas systems and other flexibilities, this currently means that they have to be taken into account for network planning as maximum load or maximum feed-in.
| Characteristics of energy cells | Planning parameters |
|---|---|
| Structure type | Residential development, trade, industry or mixed areas |
| Maximum Performance | Load and feed (all sectors) |
| Annual energy | Load and feed (all sectors) |
| Storage | Performance and capacity |
| Network data | Electricity, gas and heat |
| Sector coupling | Power-to-Gas, Power-to-Heat, etc. |
| Flexible loads | z. B. E-cars, heat pumps |
Operation of the energy cells
In order to organize a large number of decentralized systems, participants and tasks, a multi-level management system is available in the sense of automation technology, in which network parameters are regulated locally, regionally, nationally, nationally and internationally depending on the network cell level. It is based on the principle of subsidiarity, which defines that any deviations or problems that occur are primarily dealt with directly at the source of the problem and only remedied secondarily in the nearest upstream or downstream network areas.
Digitization in energy cells
The sensible operation of cells requires a minimum of monitoring and control options. Due to the inadequate initial situation, the demand for complete digitalization in medium and low voltage networks is illusory. However, the question of the minimum requirements for digitization in cellular structures is interesting.
It is not necessary to fully equip all households with measurement and control technology. In previous research work, 5 - 10 percent of all measuring points in a local network were sufficient to obtain complete transparency about voltages and currents in the network [2]. Voltage measurement data from a small percentage of intelligent measurement systems based on the respective number of connection points are sufficient for network assessment, so that separate measurement points need not be set up in the network. The prerequisite, however, is that the network operator can access the selected measurement data (voltage).
With this minimal equipment of the medium and low voltage networks with measurement, control and regulation technology, classic network expansion can be avoided. The power flows are controlled depending on the load and generation forecasts using innovative technology, e.g. B. rONT adjustable local power transformer.
Energy cell management
The heart of the cell structure is the EZM (energy cell management). In the simplest case, this device collects all the necessary information for each cell and is equipped with algorithms that enable the cell to operate as efficiently as possible in a variety of scenarios. In the second step, the communication between cells can also be mapped, whereby further balancing processes are possible with superordinate algorithms.
With the EZM u. a. the following goals can be achieved [2]:
- Network optimization in the distribution network by controlling fluctuating regenerative feeds and loads, whereby generation and load peaks can also be reduced in the low voltage through load shifting and, at best, even intermediate storage,
- Use of decentrally generated "green electricity" directly on site,
- Relief of the medium-voltage networks through the controls in the local network,
- Targeted inter-cell curtailment of feed-in systems when voltage is exceeded.
- With the EZM, the power and energy balance (degree of self-sufficiency) of the cell becomes visible.
- In favorable cases (at least frequency control device in the network), the control center can be used for a black start of the cell.
Information security
The information security has achieved very great importance in cellular energy systems because the communication structures are becoming increasingly complex with the growing number of einzubindenden plants. The security requirements must be taken into account right from the start, because they can often no longer be included at a later date or only with a disproportionate amount of effort. The architecture of the IT and communication systems and the systems themselves must be equipped and connected in such a way that cellular operation is possible. First of all, it is necessary that all ICT components necessary for the operation of a cell can be supplied with electricity, which therefore either has to come from backup solutions (batteries, diesel generators, etc.) to be dimensioned accordingly or from the cell itself. It must be ensured that not only the primary ICT components such as control computers must be taken into account, but also secondary ICT components such as routers or switches, which are particularly necessary for maintaining communication. It should be noted that different communication technologies (wired, radio, etc.) have different requirements with regard to the minimum necessary components to guarantee the communication link [1].
Case studies and projects for cellular energy systems
Trend-setting projects have been and are being carried out, which deal primarily with the integration of storage systems, sector coupling, digitization and the opening up of new business areas. In the private sector, the cellular principle has long been used extensively, with intelligent energy management systems and energy storage systems guaranteeing security of supply, increasing the self-consumption rate and minimizing the grid connection capacity .
- Bordesholm VBB
- C / sells - cellularity, participation and diversity
- E-Energy - 'Smart Energy made in Germany '
- IREN2 Wildpoldsried
- Copernicus ENavi
- LINDA Niederschönfeld
- Mannheim model city ( moma ) - cellular energy system in the E-Energy program
- PolyEnergyNet
- Portal Green
- Smart network cell SoLAR - Allensbach-Radolfzell
- SmartRegion Pellworm
- SWARM
- ZellNetz2050 - Simulation of the construction of cellular energy network structures
- Cellular system - Max Bögl plant in Neumarkt / Upper Palatinate
literature
- W. Bühring, M. Reinhart, H. Golle, G. Kleineidam: The Cellular Approach - Business Models Using Efficient Smart Buildings to Push Renewable Energy . In: Proceedings of the int.ETG-Congress 2019, May 8-9, 2019, Esslingen, Germany . ISBN 978-3-8007-4954-6 .
- Fifth monitoring report on the energy transition . (PDF) Federal Ministry for Economic Affairs and Energy (BMWi), 2016; accessed on April 5, 2018
- H. Hoppe-Oehl, G. Kleineidam: Will the energy system of the future be cellular? Report from the workshop “The cellular approach - digital decentralized decarbonising”. In: ETG journal , 02/2018, pp. 38–39
- A. Kießling, M. Khattabi: Cellular system model for smart grids combining active distribution networks and smart buildings. Energy-Efficient Computing and Networking . In: Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering , 2011, Volume 54, Part 5, pp. 225–242, doi: 10.1007 / 978-3-642-19322-4_24
- G. Kleineidam, S. Lochmüller: Digitization Links Energy Management and Trading in a Cellular Distribution Grid . In: Proceedings of the int. Conference iSEnEC, July 17-18, 2018, Nürnberg, Germany .
- G. Kleineidam, M. Krasser, M. Reischböck: The Cellular Approach - Smart Energy Region Wunsiedel, Testbed for Smart Grid, Smart Metering and Smart Home Solutions . Springer Electrical Engineering, 2016, doi: 10.1007 / s00202-016-0417-y
- The cellular approach: the basis of a successful, cross-regional energy transition . Study by the Energy Technology Society in the VDE (ETG). VDE e. V., Frankfurt am Main 2015
- Cellular energy system: A contribution to the specification of the cellular approach with recommendations for action . Study by the Energy Technology Society in the VDE (ETG). VDE e. V., Frankfurt am Main 2019
Web links
- Cellular System Model for Smart Grids Combining Active Distribution Networks and Smart Buildings . doi: 10.1007 / 978-3-642-19322-4_24
- E-Energy final report - results and findings from the evaluation of the six lighthouse projects (PDF)
- VDE Forum Cellular Energy System
Individual evidence
- ↑ VDE / ETG study "Cellular Energy System". Retrieved April 3, 2019 .
- ↑ Microgrids. Retrieved May 27, 2019 .
- ↑ E-Energy final report: Results and findings from the evaluation of the six lighthouse projects. Retrieved May 26, 2019 .
- ↑ B. Buchholz, A. Kießling, D. Nestle: “Individual customers” influence on the operation of virtual power plants . In: Power & Energy Society General Meeting . 2009.
- ↑ A. Kießling, G. Hartmann: Thinking about energy cyclically . 2014, ISBN 978-3-7469-7429-3 .
- ↑ Csells (Ed.): Large shop window in the solar arc of southern Germany . 2015.
- ↑ Prognos et al. (Ed.): Decentralization and cellular optimization - effects on network expansion needs. Study on behalf of N-ERGIE Aktiengesellschaft . Berlin and Nuremberg 2016.
- ↑ Reiner Lemoine Institute (Ed.): Comparison and optimization of centrally and decentrally oriented expansion paths to a power supply from renewable energies in Germany. Study . Berlin 2013.
- ↑ a b A. Kießling, S. Arndt: Public available specification (PAS) Terminology Smart Energy System . Frankfurt 2019.
- ↑ E-Energy. Retrieved May 15, 2019 .
- ↑ Model City Mannheim. Retrieved May 15, 2019 .