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Intelligent Energy Management

Authors:

Abstract

Intelligent energy management is the basis for economical and low-emission operation of decentral energy systems. This presentation gives a brief overview on the basics of an intelligent energy management system (iEMS) and explains some of its aspects (e.g., operational strategies, modeling and simulation) using concrete examples. An industrial-scale real-world laboratory was set up at Fraunhofer IISB, where, among other things, many aspects of an iEMS were implemented and demonstrated. In the framework ToSyCo an approach for the control of energy systems was developed. Two levels have been defined, which divide the operational strategy into a global level (storage schedules, load forecasts, etc.) and a local level (for real-time control, security, etc.).
© Fraunhofer
INTELLIGENT ENERGY MANAGEMENT
Intelligent Energy Systems / Energy Technologies
Dr. Christopher Lange, Dr. Richard Öchsner, Johannes Geiling, Alexandra Rueß
public
6/13/2022
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© Fraunhofer
CONTENT
Motivation
Basics
Real-world laboratory
Energy system optimization
TotalSystemControl
Summary
Publications
Contact
public
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© Fraunhofer
MOTIVATION
Motivation
Basics
Real-world laboratory
Energy system optimization
TotalSystemControl
Summary
Publications
Contact
public
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© Fraunhofer
Motivation
Typical energy infrastructures in industry consists of different energy sectors
Electrical (AC und DC)
Heating and Cooling
Gas (e.g., natural gas, hydrogen)
Other (e.g., compressed air, vacuum etc.)
The sectors are coupled via different plants (e.g., heat pump, CHP, chiller)
Intelligent energy management Consideration of all relevant couplings between the components
and combination of different intelligent operational strategies
Peak shaving
Efficiency increase
Self-consumption optimization
public
Main goals:
Reduction of CO2emissions and energy costs
cf. [IISB19]
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© Fraunhofer
BASICS
Motivation
Basics
Real-world laboratory
Energy system optimization
TotalSystemControl
Summary
Publications
Contact
public
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© Fraunhofer
Basics
Load profiles
public
Load profile: time course of the purchased electrical power, other name: load curve
Load profiles are composed of
Base load: Purchase that is always present,
depending on seasonal and calendar variables.
Peak load: Short-term high purchase that
differs significantly from the base load
Low load: Purchase, which is closer to the base load than to the peak load
High load: Purchase, which is closer to the peak load than to the base load
There are different definitions in literature, e.g.:
J. L. Mathieu, P. N. Price, S. Kiliccote et al. „Quantifying Changes in Building Electricity Use, With Application
to Demand Response“. IEEE Transactions on Smart Grid 2.3 (2011), S. 507518. DOI: 10.1109/TSG.2011.2145010.
P
t
peak load
high load
low load
base laod
cf. [Lan20], [Lan21a]
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Basics
Peak shaving
public
Initial situation: Load profile with the 15 min mean values of the power purchased from the energy
supplier
Definition of a purchase limit
(maximum allowed mean power
per 15 min period)
Limit can be constant or time variable
Load peak becomes visible
Highest load peak in the billing period
is relevant for electricity costs
Maximum 15 min average value
should be reduced to purchase limit
1 min values may exceed this
Load profile
power
time
Load profile with 15 min mean values
15 min
Load peak
Purchase limit (15 min)
cf. [Lan20], [Lan21a]
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Basics
Efficiency increase
Shift operation points to time periods with higher efficiency energy storages needed
Example: Chiller and recooling plant
Chiller’s efficiency (COP*) depends on thermal power
Recooling plant’s efficiency depends on ambient temperature and relative humidity
*coefficient of performance: COP = Qth / Pel
COP* of chiller
based on
cooling load
Cooling capacity of
recooling plant based
on ambient
temperature and
relative humidity
-15
0
15
30
0
25
50
75
100
0
175
350
525
700
Air temperature in °C
Fan stage 1 (dry)
Relative
humidity in %
Recooling capacity in kW
50
100
150
200
250
300
350
-15
0
15
30
0
25
50
75
100
0
175
350
525
700
Air temperature in °C
Fan stage 1 (wet)
Relative
humidity in %
Recooling capacity in kW
100
200
300
400
500
600
public cf. [Pul19a], [Pul19b]
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Basics
Self-consumption optimization
Optimization of self-consumption (e.g., energy of RES*)
Charge storage, if surplus locally generated energy is available
Discharge storage, if demand exceeds production
public *renewable energy sources
public grid Battery energy
storage system
discharging
import
Consumer
(e.g., factory)
photovoltaic plant
chargingexport
own-consumption
charging
KPIs
Self-supply rate SSR:
𝑆𝑆𝑅 = 1 − 𝐸𝑖𝑚𝑝𝑜𝑟𝑡
𝐸𝑑𝑒𝑚𝑎𝑛𝑑
Own-consumption rate OCR
𝑂𝐶𝑅 = 1 − 𝐸𝑒𝑥𝑝𝑜𝑟𝑡
𝐸𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑖𝑜𝑛
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REAL-WORLD LAB
Motivation
Basics
Real-world laboratory
Energy system optimization
TotalSystemControl
Summary
Publications
Contact
public
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© Fraunhofer
public
DC microgrid
Heat Hydrogen
Cold
Real-world lab at Fraunhofer IISB as research and demonstration platform for
sector coupling using complete institute
AC microgrid
cf. [Och19], [Mar19]
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Real-world lab at Fraunhofer IISB
Energy storages
Energy storage systems at Fraunhofer IISB
Electrical energy storages (stationary and mobile Lithium-Ion, Redox-Flow)
Thermal energy storages (hot- and cold-water storages)
Hydrogen storages (pressure, chemical)
public
Redox-flow container
with IISB’s control system
Hot water
storages
Cold water
storage
Mobile Lithium-Ion Battery Chemical hydrogen storage
system based on LOHC
cf. [Och19], [Mar19]
©Kurt Fuchs /
Fraunhofer IISB
© Fraunhofer IISB © Fraunhofer IISB © Fraunhofer IISB © Kurt Fuchs /Fraunhofer IISB
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© Fraunhofer
Real-world lab at Fraunhofer IISB
CPH, heat pump and cold storage
Application CHP* combined with heat storage
Increase of energy self-generation (heating, electrical power)
Utilization for peak shaving with algorithms and control
developed at IISB
Application heat pump
Utilization of residual heat in exhaust air systems
Load shedding during electrical load peaks
Application cold storage
Increasing efficiency
Increase of utilization of free cooling
Peak load reduction
public *combined heat and power plant cf. [Lan21b], [Mar19]
©Kurt Fuchs / Fraunhofer IISB
©Kurt Fuchs / Fraunhofer IISB
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© Fraunhofer
Real-world lab at Fraunhofer IISB
Hydrogen technology system integration
Fuel cell, electrolyzer, hydrogen storage
Development and investigation of hydrogen systems
Characterization of fuel cells and electrolyzers
Development of component models and simulations
Model based development of operational strategies
Hydrogen test bench:
Gas mixture and conditionings system
Measurement data of a fuel cell
experiment
LOHC container for investigation on long-
term storage of electrical energy
050 100 150 200 250 300
0
10
20
30
40
50
60
Spannung [V], Wirkungsgrad [%]
Strom [A]
0
2000
4000
6000
8000
10000
12000
Leistung [W]
Spannung
Leistung
public cf. [Ste18]
© Kurt Fuchs / Fraunhofer IISB © Kurt Fuchs / Fraunhofer IISB
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Real-world lab at Fraunhofer IISB
Application platform for hydrogen
public
Fuel cell
Electrolyser
Hydrogen
Pressure storage
Battery
e-motor drive drain
Drive drain
Vehicles
Stationary applications
Mobile applications
Public grid
Hydrogen
DC grid
AC grid
Waste gas
LOHC Reactor
uncharged LOHC
charged LOHC
Photovoltaic
LOHC
Test bench
Application platform: control algorithms based on simulations
Source: Fraunhofer IISB
cf. [Gei21]
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© Fraunhofer
ENERGY SYSTEM OPTIMIZATION
Motivation
Basics
Real-world laboratory
Energy system optimization
TotalSystemControl
Summary
Publications
Contact
public
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© Fraunhofer
Energy system optimization
Simulation
Advanced energy system simulation
Data analysis methods and tools
Model library for energy-related plants
and components, e.g., energy storages,
generators like heat pump, chiller, CHP,
PV, aqua-thermal plant etc.
Dimensioning algorithms for
applications like peak shaving and
increase of self-supply etc.
Non-invasive optimization of energy systems
considering all relevant energy sectors
Scenario-based study of adjustments and
extensions
public
Free Loadprofile-Analysis-
Tool, available online:
https://www.proenergie-
bayern.de/de/veroeffentli
chungen.html
Simulation tool for the energy
building infrastructure based on
a component library as well as
intelligent operational strategies
(project: ProEnergie Bayern)
cf. https://www.energy-seeds.org/
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© Fraunhofer
Energy system optimization
Data-based modelling of energy system components
Model library for energy system components
Data-based approach and use of AI
Training of model with historical measurement data
Automated process for easy transfer to other applications
public
Train and
optimize model
data Preprocess and splitting of data
Trained model
Validate model
Training data
Validation data
Comparison of measurement and two distinct models
Power
Measurement
model SVR_1
model SVR_2
cf. https://www.energy-seeds.org/
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Energy system optimization
Automation
Implementation of innovative plant concepts for energy systems
Realization of demonstrators and prototypes
Implementation of control and measurement functions according to IEC 61131
Plant characterization and functionality validation
Heat pump system for heat
recovery from exhaust air
Efficient connection to cooling
network via transmission station
Large cold storage as intelligent
component in the cooling network
public
Overview screen for visualization of a
CHP plant (HMI)
cf. https://www.energy-seeds.org/
© Fraunhofer IISB © Fraunhofer IISB © Fraunhofer IISB© Fraunhofer IISB
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© Fraunhofer
TOSYCO
Motivation
Basics
Real-world laboratory
Energy system optimization
TotalSystemControl
Summary
Publications
Contact
public
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© Fraunhofer
TotalSystemControl
Framework for an intelligent energy management system (iEMS)
public
Global level
Load prognosis
Superior operating strategy
Schedules for storage operation
Peak shaving
Local level (PLC*)
Safety functions
Basic functionality, autonomous operational strategy
Physical inputs and outputs
Operating unit for the plant
*programmable logic controller
Electrical Energy
Storage
(BESS)
Cold Thermal
Energy Storage
(CTES)
Combined Heat
and Power Plant
(CHP)
Heat Pump
System
(HPS)
TotalSystemControl (ToSyCo)
communication, data archiving, storage scheduler,
load management, peak shaving, prognosis
Weather
Prognosis
(external)
Hydrogen
Storage System
(HSS)
Redox-Flow
Battery
(RFB)
Global level
Local level
cf. [Lan19]
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TotalSystemControl
Operational strategies
Example: Extension of a heat/electricity-controlled CHP unit to include peak shaving functionality
Division of the thermal energy storage into four virtual zones, reserved zone for peak shaving
Intelligent operational strategy (including FSM) for retrofitting existing CHP systems
Battery system for increasing the dynamics (e.g., start-up process of the CHP)
public
Measurement result for
peak shaving with CHP
and battery. 18 %
reduction of peak
*finite state machine
SOCmax
SOCps
SOCmin
Peak active 0 1 0 1
CHP on 1 1 0 0
charge discharge
Full
Peak shaving
operation
Normal and
peak shaving
operation
Empty
= starting
points
cf. [Lan21a]
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© Fraunhofer
TotalSystemControl
Load forecasting
Methods
Time series models (ARIMA)
Artificial Neural Networks
Machine learning algorithms
Standalone implementation
Automated process
Integration in predictive control algorithms
Accuracy:
Electrical load: MAPE 5%
Thermal load: MAPE 10 %
public
Parameter determination
Prognosis algorithm
Historical data Data preprocessing
prognosis data
Load forecast
Cooling load
Forecast
Thermal power in kWEl. power in kW
Production plant
Forecast of cooling load (top), which is strongly shaped by the operation
of a production plant (bottom)
cf. [Mar19]
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© Fraunhofer
SUMMARY, PUBLICATIONS, CONTACT
Motivation
Basics
Real-world laboratory
Energy system optimization
TotalSystemControl
Summary
Publications
Contact
public
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© Fraunhofer
General approach and summary
public
Data analytics
Data science and statistics
Diagrams, key figures Algorithm developm ent
Operational strategies
Energy flow control
Use of Artificial Intelligence
Implementation and optimization
Implementation of operational strategies
Optimization of plants and parameters
Monitoring
Measuring and logging
data processing
System optimization
Efficiency & profitability
Sim ulation
Component models
Plant dimensioning
System simulation, scenarios
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© Fraunhofer
Scientific papers and books
[Gei21] J. Geiling, M. Steinberger, F. Ortner, R. Seyfried, A. Nuss, F. Uhrig, C. Lange, R. Öchsner, P. Wasserscheid, M. März, P. Preuster.
Combined dynamic operation of PEM fuel cell and continuous dehydrogenation of perhydro-dibenzyltoluene”. International
Journal of Hydrogen Energy 46.72 (2021), S. 35662 35677. ISSN: 0360-3199. DOI: 10.1016/j.ijhydene.2021.08.034
[Lan20] C. Lange, A. Rueß, A. Nuß, R. Öchsner, M. März. „Dimensioning battery energy storage systems for peak shaving based on a
real-time control algorithm“. Applied Energy 280 (2020), 115993. ISSN: 306-2619. DOI: 10.1016/j.apenergy.2020.115993.
[Och19] R. Öchsner, A. Nuß, C. Lange, A. Rueß. „Research Platform: Decentralized Energy System for Sector Coupling“. Chemical
Engineering & Technology 42.9 (2019), S. 18861894. DOI: 10.1002/ceat.201800714.
[Pul19a] P. Puls, C. Lange, R. Öchsner. „Hybrid Cooling Towers in a FreeCooling Application: Modeling and Field Measurement
Verification“. Chemical Engineering & Technology 42.9 (2019), S. 1871 1878. DOI: 10.1002/ceat.201800712.
[Mar19] M. März, R. Öchsner (Hrsg.). „Innovative Technologien für intelligente dezentrale Energiesysteme. Stuttgart: Fraunhofer
Verlag (2019). ISBN: 9783839614860.
public
Relevant publications (1)
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© Fraunhofer
Relevant publications (2)
PhD-Thesis
[Lan21a] C. Lange. „Energiesektoren-übergreifende Lastspitzenreduktion mit elektrischen und thermischen Energiespeichern“. PhD-
Thesis, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) (2021). URN: urn:nbn:de:bvb:29-opus4-169778.
[Pul19b] P. Puls. „Simulationsgestützte Effizienzoptimierung von industriellen Kaltwassersystemen mit thermischen Speichern“. PhD-
Thesis, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) (2019). URN: urn:nbn:de:bvb:29-opus4-108054.
[Ste18] M. Steinberger. „Verstromung von wasserstoffreichen Gasgemischen mit PEM-Brennstoffzellen am Beispiel einer
Epitaxieanlage“. PhD-Thesis, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) (2018). ISBN: 978-3-8439-3887-7.
Presentations
[Lan21b] C. Lange. „BHKW des Jahres 2020. BHKW mit Wärmespeicher und Batterie zur Strom-/Wärmeversorgung sowie
Lastspitzenreduktion “. Presentation. BHKW 2021 Innovative Technologien und neue Rahmenbedingungen, 09.11.2021
10.11.2021, Magdeburg (2021). DOI: 10.13140/RG.2.2.26423.80803.
[IISB19] IISB. "Energiesysteme neu denken“. Symposium. Presentations (2019). Available online:
https://www.iisb.fraunhofer.de/en/press_media/events/eroeffnung_bau_b.html (access: 15.03.2021).
[Lan19] C. Lange, A. Nuß, A. Rueß, R. Öchsner. „Total System Control (ToSyCo) for Peak Shaving and Efficiency Enhancement“.
Presentation. International Renewable Energy Storage Conference (IRES), 12.03.2019 14.03.2019, Düsseldorf (2019). DOI:
10.13140/RG.2.2.13002.03520.
public
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© Fraunhofer
Contact
Fraunhofer Institute for Integrated Systems
and Device Technology IISB
Schottkystr. 10
91058 Erlangen, Germany
www.iisb.fraunhofer.de
www.energy-seeds.org
public
Founded by:
Project website for ProEnergie
PROENERGIE -BAYERN
Effizienz- und Flexibilitätsgewinn durch
Optimierung von Betriebsstrategien der energetischen Gebäudeinfrastruktur
basierend auf prognostizierten Energiebedarfen der Produktion
Dr.
-Ing. Christopher Lange
Dr.
-Ing. Richard Öchsner
Johannes Geiling
+49 (0) 9131 761
-107
+49 (0) 9131 761
-116
+49 (0) 9131 761
-488
Send mail
to C. Lange
Send mail to R. Öchsner
Send mail to J. Geiling
28
Presentation
Full-text available
The presentation discussed the use of simulations for optimising energy systems, focusing on the challenges and strategies for efficient operational of energy systems, involved plants and storages and the application on heating grids. Several realisation types for operational strategies where presented followed by a concrete example consisting of a combined heat and power plant, a thermal energy storage and a battery from the real-world laboratory for decentral intelligent energy systems at Fraunhofer IISB. Simulations are the backbone of the optimisation process, as they enable the non-inversive investigation of the system. They are used for planning and optimisation, for load prognosis, grid analysis and management and energy efficiency measures. Additionally, the presentation covered the optimization of heat networks through multi-stage simulation-based operational enhancements based on the services in leveraging flexibility for the energy transition of VK Energie. Overall, the presentation provided insights into the complexities of energy system optimisation and the practical applications of simulation tools in this context.
Presentation
Full-text available
The presentation covered the project ProEnergie - Bayern and the energy system at Eirenschmalz. In ProEnergie, strategies and software tools were developed that support companies in increasing the efficiency and flexibility of their energetic building infrastructure. Industrial companies from various branches (automotive engineering, metal, lightweight construction, technical textiles, plastics, ceramics) as well as the two Fraunhofer institutes IISB and IPA worked on the project. Subsequently, the company Eirenschmalz presented their energy concept and the expanded energy system at the Schwabsoien site, which showed a real example of applications of the software tools from ProEnergie.
Article
The growth of every economy relies heavily on the availability and proper management of electrical energy in industrial and domestic applications. This growth necessitated the need for efficient and accurate measurement of electrical energy. In this paper, the principle of Hall Effect was deployed in the design and implementation of a low-cost close loop Hall Effect sensor for measuring instantaneous current. The output of the measurement is visualized through an LCD and can be interfaced to a PC for real-time graphing. The calibration result showed that the developed system has a relative error of 5.30% and can measure up to ±127.39 Ampere.
Presentation
Full-text available
Article
Full-text available
Hydrogen storage in liquid organic hydrogen carriers (LOHC) such as the substance system dibenzyltoluene/perhydro-dibenzyltoluene (H0/H18-DBT) offers a promising alternative to conventional methods. In this contribution, we describe the successful demonstration of the dynamic combined operation of a continuously operated LOHC reactor and a PEM (polymer exchange membrane) fuel cell. The fuel cell was operated stable with fluctuating hydrogen release from dehydrogenation of H18-DBT over a total period of 4.5 h, reaching electrical stack powers of 6.6 kW. The contamination with hydrocarbons contained in the hydrogen after activated carbon filtering did not result in any detectable impairment or degradation of the fuel cell. The proposed pressure control algorithm based on a proportional integral (PI) controller proved to be a robust and easy-to-implement approach to enable the dynamic combined operation of LOHC dehydrogenation and PEM fuel cell.
Thesis
Full-text available
Peak loads cause high and unpredictable loads on the power grids and increased transmission losses in the distribution networks. The compensation of short-term high electrical energy demand also requires inefficient and expensive peak load power plants as well as oversized grid components. In order to achieve an electrical energy demand by larger consumers that is as even as possible, the grid operators set financial incentives. These include a demand rate, which depends on the maximum power value during the billing period. A reduction of the peak loads thus opens up high savings potentials for industrial and commercial companies. The methodology and application of peak shaving across different energy sectors as well as the influence on the energy system are investigated in the present thesis. In addition to electrical energy storage systems, thermal plants are also used for peak shaving to increase the reduction potential, which is different from existing literature. This includes heat and cold water supply systems, which are often part of industrial energy systems. The thesis focuses on a combined heat and power plant with heat energy storage and a cooling plant with cold thermal energy storage. However, the approach can be transferred to similar components. The energy storages provide the flexibility, which is needed for the additional usage of the plants for peak shaving. Data-based models are used to represent the behavior of the components (plants, energy storages and peripherals) in simulations, which enable a non-invasive investigation of the cross-sectorial peak shaving. Peak shaving with the plants and storages requires algorithms and operational strategies for the detection of relevant peak loads, calculation of setpoints as well as for the operation in normal and peak modes. In comparison to the state of the art, relevant characteristics of the components (e.g. startup procedures) are fully taken into account. The methods can be transferred to fields, which were not considered in the thesis, e.g., compressed air and air reservoir. The overall objective is to comply with a power limit, which can be varied over time to apply for individual network fees like atypical network usage. The models and operational strategies are merged in an expandable and flexible simulation environment. This is used to present and investigate various scenarios as well as to optimize components and parameters. The components are linked dynamically within the program via a netlist, which greatly simplifies extensions and thus enables extensive investigations. The simulations show that a battery is necessary to observe a predefined load limit, as it can be operated very dynamically and provides a continuously variable output power. In the first scenario, a battery system is considered. A peak shaving potential of about 10 % is determined for the parameters of a reference system, which shows load peaks in the range of one Megawatt. This leads to a payback time of less than five years. With the additional consideration of a combined heat and power plant with thermal energy storage this value increases to approx. 18 %. A combination with a cold thermal energy storage shows a potential of 21 %. This leads to an annual saving of 21 thousand euros assuming a demand rate of 100 euros per kilowatt. A second annual data set from the reference system confirms a similar impact of the measures on total savings. If the normal operation of the CHP is also taken into account, the savings are in the range of 139 thousand euros per year, which results in a payback period of less than three years. As the absolute results are strongly dependent on the plant dimensions, a method for the calculation of the reduction potential with variation of nominal power and capacity of the plants and storages is shown and applied for numerous parameter sets. The algorithms and operational strategies were implemented into a reference system. It provides measurements, which are used for validation of the simulations. Compared to the measurements, only minor differences with a mean absolute error of four kilowatts occur for the resulting transformer power. The present thesis thus provides an approach for planning and realization of the successful cross-sectorial peak shaving. The thesis also illustrates the exemplary application of component dimensioning, optimization of algorithm parameters and implementation of operation strategies in a real system.
Thesis
Full-text available
In der vorliegenden Arbeit werden verschiedene Möglichkeiten zur Optimierung der Energieeffizienz in Kaltwassersystemen untersucht und gegenübergestellt. Die Kälte-versorgungsinfrastruktur des Fraunhofer-Instituts für Integrierte Systeme und Bau-elementetechnologie IISB in Erlangen wird dabei als Referenzsystem sowie als Platt-form für die Umsetzung abgeleiteter Maßnahmen herangezogen. Ein besonderes Teil-ziel dieser Arbeit stellt die Gegenüberstellung der Einsparpotenziale von konventionel-len Möglichkeiten der Effizienzoptimierung mit innovativen Maßnahmen, wie dem Ein-satz von freier Kühlung und der Nutzung eines Kältespeichers, dar. Die Implementie-rung innovativer Anlagenkonzepte ist üblicherweise mit einem erhöhten technischen Aufwand verbunden. Ferner hängen die Effizienzpotenziale von individuellen Randbe-dingungen des betrachteten Systems ab. Aus diesen Gründen wird im Vorfeld der Um-setzung ein Simulationswerkzeug entwickelt, mit dem sich die Systemeffizienz in Ab-hängigkeit verschiedener Randbedingungen untersuchen lässt. Um eine Basis für die Bewertung unterschiedlicher Maßnahmen herzustellen, wurde das Referenzsystem analysiert. Hierbei wurde eine relativ geringe Auslastung der vor-handenen Kältemaschinen festgestellt, welche zusammen mit einem hohen Kaltwasser-Volumenstrom und einer geringen Temperaturspreizung zwischen Vorlauf und Rück-lauf des Kältesystems eine niedrige Gesamteffizienz der Kälteanlage verursachte. Auf Basis dieser Erkenntnisse wurde eine Methodik zur Erhöhung der Anlageneffizienz abgeleitet. Diese beinhaltet die Absenkung des Kaltwasser-Volumenstroms, den Einsatz eines Kältespeichers zur Erhöhung der Auslastung der Kältemaschine sowie den Ein-satz von freier Kühlung in Zeiträumen mit niedriger Kältelast. Um das Einsparpotenzial des Kältespeichers und der freien Kühlung zu quantifizieren, wurden Modelle für die wichtigsten Komponenten des Kältesystems entwickelt und in ein Systemmodell inte-griert. Die Effizienz- und Einsparpotenziale der beiden im Modell betrachteten Techno-logien wurden anschließend denen der umgesetzten, konventionellen Maßnahmen ge-genübergestellt. Die Ergebnisse der Simulationen implizieren, dass der Einsatz eines Kältespeichers und der freien Kühlung signifikante Einsparpotenziale aufweist. Mit Hilfe eines Kaltwasser-speichers mit 80 m³ Volumen lassen sich etwa 10 % der jährlichen, betriebsgebunden Kosten des Referenzsystems einsparen. Die Kosteneinsparung durch Nutzung von frei-er Kühlung liegt bei etwa 12 %. Dabei ist zu berücksichtigen, dass freie Kühlung in den Sommermonaten aufgrund hoher Umgebungstemperaturen nicht betrieben werden kann. Das Einsparpotenzial ergibt sich somit allein aus der Winterperiode, in welcher die Einsparungen höher liegen als der Jahresdurchschnittswert von 12 %. Die konven-tionellen Effizienzmaßnahmen wiesen dagegen ein Einsparpotenzial von etwa 20 % auf, setzten sich jedoch aus zahlreichen, individuellen Optimierungsmaßnahmen im Kälte-system zusammen. Der geplante Kältespeicher konnte aufgrund eines Bauverzuges nicht im Rahmen der vorliegenden Arbeit umgesetzt werden. Die Implementierung der freien Kühlung wurde hingegen erfolgreich abgeschlossen und das Einsparpotenzial untersucht. Die experimentellen Ergebnisse stehen dabei in guter Übereinstimmung mit den Prognosen des Simulationsmodells. Während des Betriebs der freien Kühlung wurde ein Einsparpotenzial von etwa 47 % gegenüber der Kältemaschine vorausge-sagt, welches mit einem Wert von 50 % der umgesetzten Anlage leicht übertroffen wurde.
Article
In order to reduce power peaks in the electrical grid, battery systems are used for peak shaving applications. Under economical constraints, appropriate dimensioning of the batteries is essential. A dimensioning process is introduced consisting of a simulation environment to determine the behavior of the energy system, a real-time peak shaving control algorithm and an optimization process for detection of battery and algorithm parameters. The dimensioning process is investigated on the basis of four exemplary load profiles and in comparison to a conventional approach. Deviations between -7% and 75% for capacity and up to 43% for discharging power indicate undersized batteries using the conventional approach. The proposed approach relies on 1-min measurement data and does not require prediction data, leading to accurate dimensioning results for a given load profile, as verified in simulation. The practical use and effectiveness of the control algorithm is proven in a real-world laboratory. A battery system of 60 kWh capacity and 65 kW maximum power achieved successful peak load reduction by 50 kW (8%) for an a priori defined limit of 570 kW. The comparison with simulation shows only small deviations below 17 kW (4.1%) for the resulting load profile proving the realistic representation of an energy system in simulation.
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Industrial facilities usually need multiple energy subsystems, e.g. for heat, cold and electric power supply. Normally those energy subsystems are controlled locally and independent of each other. Coupling of the different subsystems can open up additional potentials. Fraunhofer IISB developed a demonstration and research platform for investigation of the benefits of such sector coupling. A major precondition is to understand the energy flows in the system as well as establishing an overall and flexible system control to realize the required algorithms for setting up an intelligent decentralized energy system. Major components of the overall system are various storages, which extend the degree of freedom for sector coupling as well as increase the effectiveness of the different subsystems.
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In this paper, the energy‐saving potential of free cooling in chilled water systems is investigated. As a preliminary study, simulation was used to quantify the performance of free cooling in a given reference system. In order to reduce computational effort for the simulation of long time periods, simplified models for dry and evaporative cooling were developed. The simulation results indicate that free cooling reduces the electric energy demand for cold supply almost by half. In a follow‐up investigation, free cooling was implemented in the reference system. The actual energy‐savings showed good agreements with the simulation forecasts and confirmed the feasibility of the concept.
Verstromung von wasserstoffreichen Gasgemischen mit PEM-Brennstoffzellen am Beispiel einer Epitaxieanlage
  • M Steinberger
M. Steinberger. "Verstromung von wasserstoffreichen Gasgemischen mit PEM-Brennstoffzellen am Beispiel einer Epitaxieanlage". PhD-Thesis, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) (2018). ISBN: 978-3-8439-3887-7.