ORCID Profile
0000-0003-0857-6760
Current Organisations
Universität Kassel
,
Fraunhofer IEE (Energy Economics and Energy System Technology)
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Publications
Implementation and validation of WECC generic photovoltaic system models in DIgSILENT PowerFactory
Publisher: IEEE
Date: 07-2016
Cost-Benefit Analysis of Battery Storage System for Voltage Compliance in Distribution Grids with High Distributed Generation
Publisher: Elsevier BV
Date: 11-2016
Pandapipes: An Open-Source Piping Grid Calculation Package for Multi-Energy Grid Simulations
Publisher: MDPI AG
Date: 26-11-2020
DOI: 10.3390/SU12239899
Abstract: The increasing complexity of the design and operation evaluation process of multi-energy grids (MEGs) requires tools for the coupled simulation of power, gas and district heating grids. In this work, we analyze a number of applicable tools and find that most of them do not allow coupling of infrastructures, oversimplify the grid model or are based on inaccessible source code. We introduce the open source piping grid simulation tool pandapipes that—in interaction with pandapower—addresses three crucial criteria: clear data structure, adaptable MEG model setup and performance. In an introduction to pandapipes, we illustrate how it fulfills these criteria through its internal structure and demonstrate how it performs in comparison to STANET®. Then, we show two case studies that have been performed with pandapipes already. The first case study demonstrates a peak shaving strategy as an interaction of a local electricity and district heating grid in a small neighborhood. The second case study analyzes the potential of a power-to-gas device to provide flexibility in a power grid while considering gas grid constraints. These cases show the importance of performing coupled simulations for the design and analysis of future energy infrastructures, as well as why the software should fulfill the three criteria.
In vivo localized gastrocnemius subtendon representation within the healthy and ruptured human Achilles tendon.
Publisher: American Physiological Society
Date: 07-2022
DOI: 10.1152/JAPPLPHYSIOL.00084.2022
Abstract: The Achilles tendon (AT) is composed of three distinct in-series elastic subtendons, arising from different muscles in the triceps surae. Independent activation of any of these muscles is thought to induce sliding between the adjacent AT subtendons. We aimed to investigate displacement patterns during voluntary contraction (VOL) and selective transcutaneous stimulation of medial (MG
Voltage control using PV storage systems in distribution systems
Publisher: Institution of Engineering and Technology
Date: 2013
DOI: 10.1049/CP.2013.1217
Analysis of Dependencies between Gas and Electricity Distribution Grid Planning and Building Energy Retrofit Decisions
Publisher: MDPI AG
Date: 07-2020
DOI: 10.3390/SU12135315
Abstract: Most macroeconomic studies predict a decline in final energy demand and the use of natural gas in the heating sector in Europe. In the course of building retrofitting, gas-based heating systems are predominantly replaced by electricity-based solutions. This influences the business models of electricity and especially gas distribution network operators (DNOs), where grid charges tend to rise. The resulting feedback effect could accelerate the decrease of demand and finally lead to the defection of the gas grid—an effect that has been neglected in energy system analysis so far. We present a multi-agent simulation with a rule-based gas and electricity DNO model and a building retrofit optimization model to analyze these interdependencies during the transformation path, focusing on the role of different technical, economic, and regulatory triggers. Our case studies for a real grid area of a German city shows that an interplay of the gas and electricity DNO’s strategy, as well as the building-, heating system-, grid-, and trigger-configuration, determine the decision on the extension, continuation, or defection of the gas grid infrastructure. Finally, strategies for how to reduce the risk of a gas grid defection, which are relevant for DNOs, policy makers, and creators of macro-economic models, are discussed.
Tendon length estimates are influenced by tracking location
Publisher: Springer Science and Business Media LLC
Date: 06-05-2022
DOI: 10.1007/S00421-022-04958-8
Abstract: Measurement of medial gastrocnemius (MG) tendon length using ultrasonography (US) requires the muscle–tendon junction (MTJ) to be located. Previously, the MG MTJ has been tracked from different proximo-distal locations near the MTJ, which could influence estimates of tendon length change due to the different characteristics of the aponeurosis and tendon. We used US to evaluate the effect of tracking point location on MG MTJ displacement during maximal and submaximal (10, 20 and 30% of the non-injured maximal) isometric plantar flexion contractions. Displacement behaviour of MTJ was tracked from (1) the exact MTJ and (2) from an insertion point of a muscle fascicle on the aponeurosis 1.3 ± 0.6 cm proximal to the MTJ, in both limbs of patients with unilateral Achilles tendon rupture (ATR) ( n = 22, 4 females, 42 ± 9 years, 177 ± 9 cm, 79 ± 10 kg). In the non-injured limb, displacement (1.3 ± 0.5 cm vs. 1.1 ± 0.6 cm) and strain (6.7 ± 2.8% vs. 5.8 ± 3.3%) during maximal voluntary contraction were larger when tracking a point on the aponeurosis than when tracking the MTJ (both p 0.001). The same was true for all contraction levels, and both limbs. Tracking a point on the aponeurosis consistently exaggerates estimates of tendon displacement, and the magnitude of this effect is contraction intensity-dependent. When quantifying displacement and strain of the Achilles tendon, the MTJ should be tracked directly, rather than tracking a surrogate point proximal to the MTJ. The latter method includes part of the aponeurosis, which due to its relative compliance, artificially increases estimates of MTJ displacement and strain.
Modelling and dynamic performance of inverter based generation in power system studies: An international questionnaire survey
Publisher: Institution of Engineering and Technology (IET)
Date: 10-2017
Sizing and grid impact of PV battery systems - A comparative analysis for Australia and Germany
Publisher: IEEE
Date: 09-2015
Muscle-tendon morphomechanical properties of non-surgically treated Achilles tendon 1-year post-rupture
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.CLINBIOMECH.2021.105568
Abstract: Achilles tendon rupture appears to alter stiffness and length of the tendon. These alterations may affect the function of tendon in force transmission and in energy storage and recovery. We studied the mechanical properties of the Achilles' tendon post-rupture and their association with function. Twenty-four (20 males, 4 females) participants (mean age: 43 y, 176 cm, 81 kg) were recruited. Ultrasonography and dynamometry were used to assess the muscle-tendon unit morphological and mechanical properties of non-surgically treated patients 1-year post rupture. Injured tendons were longer with difference of 1.8 cm (95%CI: 0.5-1.9 cm P < 0.001), and thicker by 0.2 mm (0.2-0.3 mm P < 0.01). Medial gastrocnemius cross-sectional area was 1.0 cm Longer Achilles tendon resting length was associated with poorer self-evaluated functional outcome. Although the stiffness of non-surgically treated and uninjured tendons was similar 1-year post rupture, plantar flexion strength deficit was still present, possibly due to shorter medial gastrocnemius fascicle length.
Methods for Analysis and Quantification of Power System Resilience
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2023
A new combined control algorithm for PV-CHP hybrid systems
Publisher: Elsevier BV
Date: 2018
Exploration of muscle–tendon biomechanics one year after Achilles tendon rupture and the compensatory role of flexor hallucis longus
Publisher: Elsevier BV
Date: 05-2023
A GIS-Based Planning Approach for Urban Power and Natural Gas Distribution Grids with Different Heat Pump Scenarios
Publisher: MDPI AG
Date: 05-08-2020
DOI: 10.3390/EN13164052
Abstract: Next to building insulation, heat pumps driven by electrical compressors (eHPs) or by gas engines (geHPs) can be used to reduce primary energy demand for heating. They come with different investment requirements, operating costs and emissions caused. In addition, they affect both the power and gas grids, which necessitates the assessment of both infrastructures regarding grid expansion planning. To calculate costs and CO2 emissions, 2000 electrical load profiles and 180 different heat demand profiles for single-family homes were simulated and heat pump models were applied. In a case study for a neighborhood energy model, the load profiles were assigned to buildings in an ex le town using public data on locations, building age and energetic refurbishment variants. In addition, the town’s gas distribution network and low voltage grid were modeled. Power and gas flows were simulated and costs for required grid extensions were calculated for 11% and 16% heat pump penetration. It was found that eHPs have the highest energy costs but will also have the lowest CO2 emissions by 2030 and 2050. For the investigated case, power grid investments of 11,800 euros/year are relatively low compared to gas grid connection costs of 70,400 euros/year. If eHPs and geHPs are combined, a slight reduction of overall costs is possible, but emissions would rise strongly compared to the all-electric case.
Electricity produced from photovoltaic systems in apartment buildings and self-consumption : Comparison of the situation in various IEA PVPS countries
Publisher: IEEE
Date: 06-2019
Related Organisations
Fraunhofer-Institut Für Windenergie Und Energiesystemtechnik
Location: Germany
Fraunhofer IEE (Energy Economics And Energy System Technology)
Location: Germany
Related Funding Activities
No related grants have been discovered for Martin Braun.