Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads acting on rigid retaining wall structures. A numerical study was carried out to investigate the influence of wall height; EPS geofoam type,... more
Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads acting on rigid retaining wall structures. A numerical study was carried out to investigate the influence of wall height; EPS geofoam type, thickness, and stiffness; and excitation record on seismic buffer performance. The numerical simulations were carried out using a verified FLAC code. The influence of parameter values was examined by computing the maximum forces on the walls, the buffer compressive strains, and the relative efficiency of the buffer system. In general, the closer the predominant frequency of excitation to the fundamental frequency of the wall model, the greater the seismic loads and buffer compression. The choice of earthquake record is shown to affect the magnitude of maximum earth force and isolation efficiency. However, when the wall response for walls 3 to 9 m in height are presented in this study in terms of isolation efficiency, the data from scaled accelerogra...
Light emitting diodes (LEDs) are current driven devices. So, it is essential to maintain the stability of LED voltage and current. Variation of temperature may cause of instabilities and bifurcations in the LED driver. Driving LEDs from... more
Light emitting diodes (LEDs) are current driven devices. So, it is essential to maintain the stability of LED voltage and current. Variation of temperature may cause of instabilities and bifurcations in the LED driver. Driving LEDs from an offline power source faces design challenges like it have to maintain low harmonics in input current, to achieve high power factor, high efficiency and to maintain constant LED current and to ensure long lifetime. This paper proposes the technique of harmonics reduction by using parametric optimization of Single ended primary inductor converter (SEPIC) based LED driver. Without optimization of SEPIC parameters input energy will not be properly transferred to the load and this un-transferred energy will be transmitted to the source. Consequently, the quality of input current will be hampered i.e. harmonics will contaminate the input current. Focussing this, the paper has presented the design of a non-isolated integrated-stage singleswitch constant current LED driver operating in discontinuous conduction mode (DCM) in SEPIC incorporating the design of control circuit with soft start mechanism. This LED driver has achieved a good efficiency (90.6%) and high-power factor (0.98) with reduced harmonics (3.35%). System stability has been determined and simulation studies are performed to confirm the validity of the LED driver circuit. A laboratory prototype is built to verify the functionality and performance of the proposed LED driver.
This document proposes a photovoltaic (PV) based single-phase dynamic voltage restoration (DVR) device, it eliminates both sag and swell voltage and compensates for power. The proposed system requires a power source to compensate for the... more
This document proposes a photovoltaic (PV) based single-phase dynamic voltage restoration (DVR) device, it eliminates both sag and swell voltage and compensates for power. The proposed system requires a power source to compensate for the sag/swell voltage. This system has found a simple topology for the DVR that uses PV with two DC-DC boosts converters as the DC power source for the dynamic voltage conservator. The DC/DC boost converter powered by the PV generator is applied to increase the voltage to meet the DC bus voltage requirements of the single-branch voltage source inverter (VSI). This system uses renewable energy; saves energy accordingly and supplies power to critical/sensitive loads. The control method used in this work is a Sliding Mode Control (SMC) method and relies on a phase locked loop (PLL) used to control the active filter. The effectiveness of the suggested method is confirmed by the MATLAB/Simulink® simulation results and thelaboratorial prototype. These results show the capacity of the proposed DC link control.
At the point of common coupling (PCC), the summation of two harmonic voltage vectors at same frequency is only certain if their amplitudes and phase angles are well known. Therefore, there are many cases where the phase angle difference... more
At the point of common coupling (PCC), the summation of two harmonic voltage vectors at same frequency is only certain if their amplitudes and phase angles are well known. Therefore, there are many cases where the phase angle difference between harmonic voltage vectors is unknown. In practice, for example, in calculating the steady state rating of the a.c. passive harmonic filter, arithmetic summation method is often used in determining maximal harmonic level. This summation law is very conservative as it may result in high cost of equipment ratings. Actually, a compromise should be made in taking into account the equipment safety and the risk of overrating as well as excessive costs. Based on uniform distribution of difference in phase angles, the paper provides an algorithm to calculate the probability upon which the magnitude of summation vector of two harmonic voltages may exceed a given value. On the basis of the probability and the given harmonic value, harmonic summation can be assessed. This may also result in a recommendation of another harmonic summation method for the standard IEC/TR 61000-3-6.
Three-level NPC active-front-end three-phase (3LAFE) converters can be applied to high-power medium voltage applications, with 4-quadrant unity-power-factor operation, allowing a broad range for power conversion systems, such as... more
Three-level NPC active-front-end three-phase (3LAFE) converters can be applied to high-power medium voltage applications, with 4-quadrant unity-power-factor operation, allowing a broad range for power conversion systems, such as decentralized energy distribution and utilization. Switching losses and network interaction limit the operation of 3LAFE high-power converters, especially when GTO-converters are used.
The term quadrivium refers to the study of arithmetic, music, geometry, and astronomy. The Pythagoreans referred to the study of number which are Arithmetic (Number in itself), Music (Number in time), Geometry (Number in space) and... more
The term quadrivium refers to the study of arithmetic, music, geometry, and astronomy. The Pythagoreans referred to the study of number which are Arithmetic (Number in itself), Music (Number in time), Geometry (Number in space) and Astronomy (Number in space and time). This paper presents the quadrivium as the foundation of a multidisciplinary approach to teaching basic mathematics. Through a brief but in-depth examination of two phenomena, the √2 geometric progression (a spatial sequence), and the musical overtone series (a temporal sequence) are presented in this paper. This paper presents a new relationship between number, geometry and music. While each is rather commonly known within the context of their separate disciplines, it is when combined that a remarkable relationship is uncovered.
Improving power quality play a vital role in distribution systems since, these are majorly connected to nonlinear loads. Nonlinear loads generate harmonics which in turn disturb the source of supply. The damped double tuned filters can be... more
Improving power quality play a vital role in distribution systems since, these are majorly connected to nonlinear loads. Nonlinear loads generate harmonics which in turn disturb the source of supply. The damped double tuned filters can be designed either by using equivalent method or parametric method but, the parametric method is most preferable because of consideration of reactive power demand of the nonlinear load. In this proposed research paper various types of damped double tuned filters have been designed for different nonlinear loads and a comparison was made between aforementioned two methods when connected to different nonlinear loads. A flowchart has been developed to optimize the damped double tuned filter parameters and tested by using MATLAB programming.
Harmonic phenomena is one of the main problems affecting power quality in the electrical distribution networks. Harmonics transmit from customer to neighbours causing impacts on many network elements. In the industrial section, there are... more
Harmonic phenomena is one of the main problems affecting power quality in the electrical distribution networks. Harmonics transmit from customer to neighbours causing impacts on many network elements. In the industrial section, there are many traditional solutions to the harmonics problem; each solution has advantages and disadvantages. For residential customers, no one cares about harmonics due to the insignificant individual power consumption compared with industrial loads. However, with the wide increase of electronics loads in the residential sector, the researchers in this area are forced to pay more attention to reduce the impacts of harmonics in the residential sector. This Paper presents a technique for harmonic mitigation and cancellation in the residential distribution network with no added equipment or extra cost. The proposed technique only need to analyze the performance of residential loads to choose a specific arrangement of such loads in order to reach the harmonic cancellation goal. The paper also presents a simple modification to the manufactures to fulfil the same goal.
Harmonic pattern scanner expert advisor for the trading platform MT5. Scans markets on different time frames and for multiple patterns. Scanning is performed on multiple standard and custom time frames. Radar scanner shows overall scan... more
Harmonic pattern scanner expert advisor for the trading platform MT5. Scans markets on different time frames and for multiple patterns. Scanning is performed on multiple standard and custom time frames. Radar scanner shows overall scan results. Individual instrument scanning provides multi time frame scan for all harmonics and Fibonacci levels with a possibility to draw multiple objects on the chart.
Il volume propone un'esposizione storica sul pensiero musicale teorico dalla tarda antichita alla fine del medioevo, affrontando tematiche di teoria musicale, filosofia e scienza.
Power electronics play a significant role in different areas of technology, more usage of power electronic devices lead to more harmonic content and various power quality issues in the system. Therefore, power quality gains more... more
Power electronics play a significant role in different areas of technology, more usage of power electronic devices lead to more harmonic content and various power quality issues in the system. Therefore, power quality gains more significance in the current era of research. Power electronics equipment's with non-linear loads concludes with more harmonic disturbances and lower power factor. Harmonic impurities are the major problem ingredient due to the connection of non-linear load. To lessen the harmonics usually passive filters are used. The major objective of this work is to monitor and analyse the power quality of uninterrupted power supply by means of DAQ system that gathers real time data on the system and then the data is analysed using National Instruments LabVIEW. Once power quality analysis is done, a new technique of filter implementation using output transformer of the UPS was explored and passive filter was simulated using MATLAB/Simulink and then simulated filter was implemented in order to achieve power quality improvement.
This paper presents the speed control of DC motor using six pulse controlled rectifier. The conventional Proportional Integral (PI) control is used for firing angle control. The armature current is fed back and compared with reference... more
This paper presents the speed control of DC motor using six pulse controlled rectifier. The conventional Proportional Integral (PI) control is used for firing angle control. The armature current is fed back and compared with reference current representing desired speed values. The proposed system is simulated using SimPowerSystem and Control System Matlab toolbox. The time domain plot of reference and actual armature current are shown in results section. The results are satisfactory with deleterious effect on input current. The frequency plot of input current is provided to show the harmonic contents, generated as a result of control operation.
Abstract-Improved reliability and fault tolerant operation of inverter-fed variable frequency ac drives are very impor-tant for critical industrial applications. The paper describes variable frequency, variable voltage operation of a... more
Abstract-Improved reliability and fault tolerant operation of inverter-fed variable frequency ac drives are very impor-tant for critical industrial applications. The paper describes variable frequency, variable voltage operation of a three-phase induction motor drive in ...
ABSTRAK Krisis energi listrik yang melanda indonesia menyebabkan beberapa persoalan dalam bidang ketenagalistrikan, sehingga dilakukan upaya untuk mengatasi krisis energi listrik, dengan melakukan peningkatan efisiensi dari peralatan yang... more
ABSTRAK Krisis energi listrik yang melanda indonesia menyebabkan beberapa persoalan dalam bidang ketenagalistrikan, sehingga dilakukan upaya untuk mengatasi krisis energi listrik, dengan melakukan peningkatan efisiensi dari peralatan yang digunakan konsumen. Salah satu upaya yang dilakukan pemerintah dan pihak swasta (produsen lampu) untuk meningkatkan efiesiensi lampu Neon dan lampu hemat energi serta lampu LED menggantikan fungsi lampu pijar. Lampu Hemat Energi dan Lampu LED memiliki tingkat efesiensi penerangan bagus, akan tetapi lampu LED Lampu Hemat Energi (LHE) dan lampu TL memiliki beberapa karakteristik diantaranya menghasilkan distorsi harmonisa arus dan tegangan. Tujuan dilakukan penelitian untuk mengetahui pengaruh THDi dan THDv dengan metode pengukuran. Hasil dari pengujian THDi yang muncul pada kombinasi sejenis rata-rata THDi muncul 130% pada LED, pada kombinasi sejenis LHE THDi yg muncul sebesar 124% semakin menurun bila jumlah beban ditambah, pada kombinasi sejenis TL THDi yang muncul sebesar7,5%.Untuk kombinasi beban LED//LHE nilai THDi yang muncul dengan rata-rata sebesar 125%, kombinasi beban LED//TL THDi yang muncul turun hingga 105%, kombinasi beban LHE//TL THDi yang muncul turun hingga 82%, kombinasi LED//LHE//TL nilai THDi turun sebesar 80% dibanding hanya kombinasi LED//LHE. Adapun kombinasi dua jenis beban dan tiga jenis beban THDv yang muncul rata-rata 2%.
The harmonic mitigation using shunt active filters are most widely used in industrial and commercial applications. In this paper a Multi-Level Inverter is considered as DSTATCOM to compensate harmonics. The mathematical modeling of the... more
The harmonic mitigation using shunt active filters are most widely used in industrial and commercial applications. In this paper a Multi-Level Inverter is considered as DSTATCOM to compensate harmonics. The mathematical modeling of the system and design of the controller using synchronous reference frame theory is also presented. The nonlinear load generally known as diode rectifier load and an unbalanced load is simulated with the system using MATLAB/SIMULINK.
Harmonic voltages are important voltage quality parameters defined in EN 50160. For harmonic voltage studies in electricity networks, harmonic emission of loads is often modelled as harmonic current source. In this paper harmonic current... more
Harmonic voltages are important voltage quality parameters defined in EN 50160. For harmonic voltage studies in electricity networks, harmonic emission of loads is often modelled as harmonic current source. In this paper harmonic current sources were parameterised on the basis of measurements of total harmonic current emission of several different low voltage networks. Measurements from low voltage networks with different typical customer configurations were used: residential, offices and PV. A real medium voltage electricity distribution network of an Austrian distribution system operator, with significant consumption of residential and office customers, was chosen for this analysis. In order to automate the harmonic load flow calculations in DIgSILENT PowerFactory for every 10-minute interval of one week, a script in DIgSILENT Programming Language-DPL was developed. Harmonic voltage results from the harmonic load flow simulation are compared with the results of harmonic voltage measurements from power quality monitoring system installed in this network. The goal of this paper is to assess the suitability of the approach, where only background harmonics and key harmonic current sources are modelled. Since the approach provided good results, it can be used in future work as a basis for optimising the number and locations of power quality monitors in electricity distribution networks.
The problem of quality electrical energy provided to the users has arisen. This is due to the increasing presence in network of nonlinear loads.They constitute a harmonic pollution source of the network, which generate many disturbances,... more
The problem of quality electrical energy provided to the users has arisen. This is due to the increasing presence in network of nonlinear loads.They constitute a harmonic pollution source of the network, which generate many disturbances, and disturb the optimal operation of electrical equipments. This work, proposed a solution to eliminate the harmonics introduced by the nonlinear loads. It presents the analysis and simulation using Matlab Simulink of a active power filter (APF) compensating the harmonics and reactive power created by nonlinear loads in steady and in transients. The usefulness of the simulation approach to APF is demonstrated , have a better power quality insight using Matlab Simulink in order to develop new fuzzy logic controller based active power filter.
— Harmonics are found to have deleterious effects on power system equipments including transformers, capacitor banks, rotating machines, switchgears and protective relays. Transformers, motors and switchgears may experience increased... more
— Harmonics are found to have deleterious effects on power system equipments including transformers, capacitor banks, rotating machines, switchgears and protective relays. Transformers, motors and switchgears may experience increased losses and excessive heating. Shunt filters are effective in minimizing voltage distortions. This paper describes the voltage distortions generated by non-linear loads. The harmonic specifications such as harmonic factor, characteristic harmonic and non-characteristic harmonic are considered while explaining the paper. With the implementation of a passive filter at the bus with non-linear load, the harmonics are greatly reduced. For the specified power system, at all the buses the total harmonic distortion has been evaluated.
Nowadays solar power is one of the most suitable energy source for power generation. In practice, due to routine starting of solar power plant at every day, as a result of switching effects inrush current produces in grid connected... more
Nowadays solar power is one of the most suitable energy source for power generation. In practice, due to routine starting of solar power plant at every day, as a result of switching effects inrush current produces in grid connected transformer(s). Inrush current affects winding of transformer, causes of generation of harmonics and related power quality issues. Here, the calculation of inrush current and its effect on power system network is elaborated. Possible solution for reduction of inrush current by suitable techniques is discussed. Comparative analysis has been also obtained for effects of harmonics of with sequential switching technique and without inrush current reduction technique.
In power quality, harmonics problems are worse than transient events, such as lighting or voltage sags. The harmonics problems could get worse if more than one nonlinear load were connected on a system. Therefore, such distortion should... more
In power quality, harmonics problems are worse than transient events, such as lighting or voltage sags. The harmonics problems could get worse if more than one nonlinear load were connected on a system. Therefore, such distortion should be avoided to protect the power system source and the electrical devises. In this article a new technique was developed to estimate the total harmonic distortion for a system that has multiple nonlinear loads without performing detailed interconnected system analysis. This technique was successfully utilized on Matlab. The technique gives acceptable results.
Bringing together evidence preserved by Aristoxenus, Aristides Quintilianus, Ptolemy, Porphyry and the Greek musical handbooks in a unified framework, this article and its sequels show how the Classical modulation system reconstructed in... more
Bringing together evidence preserved by Aristoxenus, Aristides Quintilianus, Ptolemy, Porphyry and the Greek musical handbooks in a unified framework, this article and its sequels show how the Classical modulation system reconstructed in Lynch 2018 is confirmed by the melodies recorded in the Greek musical documents. Taken jointly, these articles will offer the first comprehensive account of the use of notation tónoi in the ancient Greek musical documents that is fully consistent with the extant technical evidence on ancient harmonic theory and with literary testimonies about the harmonic innovations introduced by the New Musicians. The present article will focus on the Classical/Hellenistic harmonic system, whereas its Imperial counterpart will be discussed in a separate article. These theoretical analyses are based upon a newly developed database (dDAGM, https://doi.org/10.5281/zenodo.5181743) which collects all the musical notes attested in the standard edition of the Greek musical fragments (DAGM), for a total of over 3,400 notes.
One of the major electrical load on a utility grid is industrial, street and residential lightings. To enhance the energy efficiency and as a measure of energy conservation, incandescent lamps (IL) are replaced with the modern lights.... more
One of the major electrical load on a utility grid is industrial, street and residential lightings. To enhance the energy efficiency and as a measure of energy conservation, incandescent lamps (IL) are replaced with the modern lights. Replacing incandescent lamps with compact fluorescent lamp (CFL) and fluorescent lamp (FL) is one of the measures taken by the authorities to reduce the energy consumption and enhance energy efficiency. Both the CFLs and LEDs are the sources of harmonics as electronic circuits are used in for their ignition. These harmonic sources adversely affect other loads connected to the same bus. It also affects the grid in terms of high reactive power demand (due to poor power factor), distortion in currents and hence overall degrading the power quality. Power quality measurements such as power factor, voltage and current total harmonic distortion (THD) are done and reported in this paper. Different scenarios are considered with full and partial replacement of incandescent lamps. A comprehensive comparison between incandescent, CFL and LED are made in terms of these power quality measurements. From the result analysis, it is noted that, the CFL consumes less active power than incandescent. But, the THD is considerably higher in CFL than incandescent. While comparing LED and CFL, the power factor of LED is found poor compared to CFL. The simulation and experimental approaches are used in this work.
The emergence of local expectations in listeners of music has been occasionally explained by assuming a sort of musical syntax or grammar. While sharing some superficial qualities, music and language structures are working differently:... more
The emergence of local expectations in listeners of music has been occasionally explained by assuming a sort of musical syntax or grammar. While sharing some superficial qualities, music and language structures are working differently: language syntax is organized in a hierarchical system, working only context-sensitively (the applicability of syntactical rules is influenced by the context), whereas musical structures, especially harmonic progressions, emerge mainly out of constructive, context-dependent processes (the context is able to establish completely new structural principles). Collected examples from musical literature of western tonal music across styles and epochs show five main principles of musical structure-building that distinguish musical models from syntactical rules: Constructivity, mappability, contextuality, individuality and contingence. The main influence of frame and context on musical expectations can be especially demonstrated by means of a harmonic progression frequently used in empirical studies as assumed syntactical violation: the neapolitan sixth chord succeeding the dominant. As a consequence, a re-interpretation of the empirical data should consider the specific context of the observed effects: they might be more a result of the introduction of the listener to a redundant stylistic model instead of the application of syntactical rules proper. According to the provided examples, structural expectations of listeners appear to be rather combinations of general familiarity to styles and composition principles, individual preferences and local framing. Based on these historical and systematic arguments, the structure of music seems to be flexible and integrative, and not bound to a syntax system.
