scholarly journals Stability Analysis of Power Hardware-in-the-Loop Simulations for Grid Applications

Electronics ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 7
Author(s):  
Simon Resch ◽  
Juliane Friedrich ◽  
Timo Wagner ◽  
Gert Mehlmann ◽  
Matthias Luther
Keyword(s):  
Low Voltage ◽  
Photovoltaic System ◽  
Special Focus ◽  
Hardware In The Loop ◽  
Time Simulation ◽  
Linear Amplifier ◽  
Grid Applications ◽  
The Stability ◽  
Transformer Model ◽  
Stability Limits

Power Hardware-in-the-Loop (PHiL) simulation is an emerging testing methodology of real hardware equipment within an emulated virtual environment. The closed loop interfacing between the Hardware under Test (HuT) and the Real Time Simulation (RTS) enables a realistic simulation but can also result in an unstable system. In addition to fundamentals in PHiL simulation and interfacing, this paper therefore provides a consistent and comprehensive study of PHiL stability. An analytic analysis is compared with a simulative approach and is supplemented by practical validations of the stability limits in PHiL simulation. Special focus is given on the differences between a switching and a linear amplifier as power interface (PI). Stability limits and the respective factors of influence (e.g., Feedback Current Filtering) are elaborated with a minimal example circuit with voltage-type Ideal Transformer Model (ITM) PHiL interface algorithm (IA). Finally, the findings are transferred to a real low-voltage grid PHiL application with residential load and photovoltaic system.

Experimental Study on Lean Blowout Limits of Turbulent Premixed Hydrogen/Ammonia/Air Mixtures

2021 ◽  
Author(s):  
Andreas Goldmann ◽  
Friedrich Dinkelacker
Keyword(s):  
Gas Turbines ◽  
Measurement Procedure ◽  
Liquid Fuels ◽  
Special Focus ◽  
Atmospheric Conditions ◽  
Ammonia Content ◽  
Lean Blowout ◽  
Combustion Properties ◽  
The Stability ◽  
Stability Limits

Abstract As the demand for greenhouse gas neutral transportation and power generation solutions is growing, alternative carbon-free fuel such as hydrogen (H2) and ammonia (NH3) are gaining more attention. Mixtures of both fuels allow the adjustment of combustion properties. With future fuels also the vision of very clean combustion can be taken into the focus, being for instance based on lean premixed and for liquid fuels prevaporized combustion for gas turbines. For the utilization of such concepts, however, flame stability is essential. In this study the upper stability limits, i.e. lean blowout of turbulent hydrogen/ammonia/air flames, is experimentally investigated in a generic non-swirl premixed burner at atmospheric conditions. Special focus is laid on a measurement setup with fully automatized measurement procedure, to reach the stability limits, as these limits tend to depend for instance on the approach speed towards the limit. The ammonia content was varied from 0 vol% to 50 vol% in 10 vol% steps with the rest being hydrogen, for a broad range of fuel-air-equivalence ratios. The lean blowout limit is increasing almost linearly with increasing fuel-air-equivalence ratios, whereas with increasing ammonia content the limit is decreasing. Furthermore, a model for the lean blowout limits were derived, which is able to predict the acquired experimental data with high accuracy.

Stability as a constraint in sagittal plane human force exertion modeling

1998 ◽  
Vol 1 (1) ◽  
pp. 23-39
Author(s):  
Carter J. Kerk ◽  
Don B. Chaffin ◽  
W. Monroe Keyserling
Keyword(s):  
Muscle Strength ◽  
Ankle Joint ◽  
Coefficient Of Friction ◽  
Sagittal Plane ◽  
Biomechanical Model ◽  
Whole Body ◽  
The Stability ◽  
Joint Center ◽  
Static Conditions ◽  
Stability Limits

The stability constraints of a two-dimensional static human force exertion capability model (2DHFEC) were evaluated with subjects of varying anthropometry and strength capabilities performing manual exertions. The biomechanical model comprehensively estimated human force exertion capability under sagittally symmetric static conditions using constraints from three classes: stability, joint muscle strength, and coefficient of friction. Experimental results showed the concept of stability must be considered with joint muscle strength capability and coefficient of friction in predicting hand force exertion capability. Information was gained concerning foot modeling parameters as they affect whole-body stability. Findings indicated that stability limits should be placed approximately 37 % the ankle joint center to the posterior-most point of the foot and 130 % the distance from the ankle joint center to the maximal medial protuberance (the ball of the foot). 2DHFEC provided improvements over existing models, especially where horizontal push/pull forces create balance concerns.

scholarly journals Reliability-Oriented Design of Inverter-Fed Low-Voltage Electrical Machines: Potential Solutions

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4144
Author(s):  
Yatai Ji ◽  
Paolo Giangrande ◽  
Vincenzo Madonna ◽  
Weiduo Zhao ◽  
Michael Galea
Keyword(s):  
Power Density ◽  
High Speed ◽  
High Performance ◽  
Low Voltage ◽  
Electrical Machines ◽  
Design Stage ◽  
Switching Frequency ◽  
Special Focus ◽  
Electrical Machine ◽  
Engineering Approach

Transportation electrification has kept pushing low-voltage inverter-fed electrical machines to reach a higher power density while guaranteeing appropriate reliability levels. Methods commonly adopted to boost power density (i.e., higher current density, faster switching frequency for high speed, and higher DC link voltage) will unavoidably increase the stress to the insulation system which leads to a decrease in reliability. Thus, a trade-off is required between power density and reliability during the machine design. Currently, it is a challenging task to evaluate reliability during the design stage and the over-engineering approach is applied. To solve this problem, physics of failure (POF) is introduced and its feasibility for electrical machine (EM) design is discussed through reviewing past work on insulation investigation. Then the special focus is given to partial discharge (PD) whose occurrence means the end-of-life of low-voltage EMs. The PD-free design methodology based on understanding the physics of PD is presented to substitute the over-engineering approach. Finally, a comprehensive reliability-oriented design (ROD) approach adopting POF and PD-free design strategy is given as a potential solution for reliable and high-performance inverter-fed low-voltage EM design.

scholarly journals Modeling and Design of the Vector Control for a Three-Phase Single-Stage Grid-Connected PV System with LVRT Capability according to the Spanish Grid Code

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2899 ◽  
Author(s):  
Alexis B. Rey-Boué ◽  
N. F. Guerrero-Rodríguez ◽  
Johannes Stöckl ◽  
Thomas I. Strasser
Keyword(s):  
Vector Control ◽  
Reactive Power ◽  
Low Voltage ◽  
Single Stage ◽  
Photovoltaic System ◽  
Lookup Table ◽  
Voltage Sags ◽  
Pv System ◽  
Low Voltage Ride Through ◽  
Three Phase

This article deals with the vector control in dq axes of a three-phase grid-connected photovoltaic system with single-stage topology and low-voltage-ride-through capability. The photovoltaic generator is built using an array of several series-parallel Suntech PV modules and is modeled as a Lookup Table (two-dimensional; 2-D). The requirements adopted when grid voltage sags occur are based in both the IEC 61400-21 European normative and the allowed amount of reactive power to be delivered according to the Spanish grid code, which avoids the disconnection of the inverter under grid faults by a limitation in the magnitude of the three-phase output inverter currents. For this, the calculation of the positive- and negative-sequences of the grid voltages is made and a conventional three-phase Phase-Locked Loop is used for the inverter-grid synchronization, allowing the control of the active and reactive powers solely with the dq components of the inverter currents. A detailed enhanced flowchart of the control algorithm with low-voltage-ride-through capability is presented and several simulations and experiments using Matlab/SIMULINK and the Controller Hardware-in-the-Loop simulation technique, respectively, are run for several types of one- and three-phase voltage sags in order to validate its behavior.

scholarly journals Derived Interaction Parameters for the TSAI-WU Tensor Polynomial Theory of Strength for Composite Materials

2001 ◽  
Author(s):  
Steven J. DeTeresa ◽  
Gregory J. Larsen
Keyword(s):  
Hydrostatic Pressure ◽  
Fiber Composite ◽  
Strength Criterion ◽  
Test Methods ◽  
Standard Test ◽  
Transverse Compression ◽  
Strength Parameters ◽  
Carbon Fiber Composite ◽  
The Stability ◽  
Stability Limits

Abstract It is shown that the two interactive strength parameters in the Tsai-Wu tensor polynomial strength criterion for fiber composites can be derived in terms of the uniaxial or non-interacting strength parameters if the composite does not fail under practical levels of hydrostatic pressure or equal transverse compression. Thus the required number of parameters is reduced from seven to five and all five of the remaining strength terms are easily determined using standard test methods. The derived interactive parameters fall within the stability limits of the theory, yet they lead to open failure surfaces in the compressive stress quadrant. The assumptions used to derive the interactive parameters were supported by measurements for the effect of hydrostatic pressure and unequal transverse compression on the behavior of a typical carbon fiber composite.

scholarly journals Arrhythmiarizikó és cardialis szövődmények áramütéses balesetet követően

2020 ◽  
Vol 161 (47) ◽  
pp. 1979-1988
Author(s):  
Dávid Pilecky ◽  
Enikő Kovács ◽  
Endre Zima
Keyword(s):  
Emergency Department ◽  
Low Voltage ◽  
Electrical Current ◽  
Developed Countries ◽  
The Body ◽  
Cardiac Complications ◽  
Special Focus ◽  
Severe Injuries ◽  
Multiple Organs ◽  
Severe Burns

Összefoglaló. Az áramütés súlyos esetben hirtelen halállal vagy több szervrendszer kiterjedt károsodásával járhat. A magasfeszültségű áramütés (>1000 V) általában súlyosabb égési sérülésekkel és magasabb kórházi mortalitással jár, mint az alacsonyfeszültségű, de a sérülések súlyosságát a feszültségen kívül a test ellenállása, az áramexpozíció ideje, az áram fajtája, erőssége és útja is befolyásolja. A kritikus állapotú vagy súlyos égési sérüléseket szenvedett betegek sürgősségi ellátása komplex és multidiszciplináris szemléletet igényel. A súlyos szövődményekkel járó áramütéses balesetek ugyanakkor a fejlett országokban ritkák: az áramütés következtében sürgősségi osztályon jelentkező betegek döntő többsége panaszmentesen vagy minor panaszokkal kerül felvételre. A ritmuszavarok az áramütéses balesetek messze leggyakoribb cardialis szövődményei, és rendszerint közvetlenül az áramütés után jelentkeznek. Az elektromos áram kamrafibrillációt vagy asystoliát is kiválthat, mely a baleset helyszínén ellátás nélkül halálhoz vezethet. Bár sok helyen elterjedt gyakorlat az áramütést szenvedett betegek rutinszerű monitorozása, a klinikailag releváns arrhythmiák összességében ritkák, és a felvételi EKG alapján diagnosztizálhatók, ezért EKG-monitorozás csak meghatározott rizikófaktorok esetén szükséges. Jelen munkánk célja összefoglalni az áramütést szenvedett betegek optimális sürgősségi ellátásával kapcsolatos legfontosabb szempontokat, különös tekintettel az áramütéses balesetet követően fellépő cardialis szövődményekre és arrhythmiákra, valamint az EKG-monitorozás indikációira. Orv Hetil. 2020; 161(47): 1979–1988. Summary. Electrical accidents (EA) may cause sudden death or severe injuries of multiple organs. High voltage injuries (>1000 V) are associated with more severe burn injuries and higher in-hospital mortality than low voltage injuries, however, the severity of complications depends on several other factors like resistance of the body, duration of current exposition, intensity, type and pathway of current. Critically ill patients with severe burns and/or other injuries require a multidisciplinary intensive treatment. However, such complications are rare in the developed countries: most patients present in the emergency department with no or minor symptoms and do not require hospital admission. Arrhythmias are the most frequent cardiac complications after EA. Electrical current may cause ventricular fibrillation or asystolia which can lead to death on the scene. In patients presenting in the emergency department, clinically relevant arrhythmias are rare and can be diagnosed by a 12-lead ECG, therefore a systematic monitoring may not be indicated. Aim of our work is to review the most frequent complications after an electrical accident with special focus on cardiac complications and arrhythmias. The other aim of the manuscript is to summarize the most important aspects of emergency treatment and indication for ECG monitoring after electrical accident. Orv Hetil. 2020; 161(47): 1979–1988.

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