Power Factor Changes Research Articles

Process deviation detection method for dry‐type air‐core reactor based on power factor frequency characteristics

AbstractTo address the problem that the process deviation of dry‐type air‐core reactors cannot be effectively detected, electrical parameters of reactor are numerically analysed at different frequencies. A new method of process deviation detection by the power factor frequency characteristic is proposed. Considering on‐site power frequency interference, a harmonic analysis method is proposed, which is based on the integer multiple of the power frequency cycle, to calculate the power factor. The results show that the resistance loss remains relatively constant at power frequency and gradually increases at higher frequencies with the number of deviation turns increases. The eddy current loss remains basically unchanged at different turn deviations and frequencies. The change laws of resistance loss and the resistance loss power factor are the same. In a double logarithmic coordinate system, resistance loss power factor changes from linear to non‐linear. The non‐linearity degree can be used to detect the process deviation. The test results are consistent with the theory, and the correctness of the detection method is verified.

Analysis of various operating modes of the microhpp asynchronous generator using the matlab simulink program

This article analyzes changes in efficiency and power factor, as well as various operating modes in the capacitor element excitation method, which is increasingly used in asynchronous generators. In this case, the sinusoidal voltage and frequency produced by the induction generator are within the rated values and different operations are compared. The studies were carried out along with the parameters obtained using the simulation model as well as real experimental verification. The simulation model was built in the Matlab Simulink package, which consisted of a rectifier, filter circuit, IGBT transistors and included a control system. In the real experiment, an asynchronous generator with a low-power squirrel-cage rotor was chosen, and sensors for measuring current and voltage were installed on the experimental stand. As a result of the analysis of transient processes occurring in different operating modes of the generator, it was found that the values of voltage, current and frequency changed from the nominal value. The results were achieved by adjusting the speed through a variable speed drive to obtain the rated speed taking into account the speed supplied to the rotor from the hydraulic turbine. At the end of the study, it was concluded that the induction generator has a number of advantages over other types of generators, including simplicity of design, low cost, and the fact that it does not consume a direct current source.

Effect of co‐substitution on complex thermoelectric compounds: The Zintl phase Ba1‐xSrxZn2‐yCuySb2 system

AbstractThree co‐substituted quaternary and quinary Zintl phases belonging to the Ba1‐xSrxZn2‐yCuySb2 (x = 0, 0.09; 0.24 ≤ y ≤ 0.42) system were prepared by the molten Pb metal‐flux method. Co‐substitution using the cationic Sr and anionic Cu for Ba and Zn was initially applied to lower the thermal conductivities and to improve the electric conductivities of these title compounds simultaneously. The homogeneities of single‐phase products were verified by powder x‐ray diffraction analysis, and the BaCu2S2‐type orthorhombic crystal structures with the Ba/Sr and the Zn/Cu mixed‐sites were refined by single crystal x‐ray diffraction analysis. Structural selectivity for the observed BaCu2S2‐type phase was rationalized by the radius ratio of cationic and anionic elements, where r+/r− > 1. DFT calculations using the three structural models revealed that the Sr and Cu substitutions can increase the structural stability and the hole carrier concentration. A series of temperature‐dependent electrical transport property measurements for BaZn1.76Cu0.24Sb2 and Ba0.91Sr0.09Zn1.70Cu0.30Sb2 successfully proved that the co‐substitution using Sr and Cu enhanced electrical conductivities, but reduced the Seebeck coefficients resulting in the slight change in power factor.

Reliability Analysis of a Multilevel Inverter Applied to Stratospheric Drones Using Fault Tree Analysis

Stratospheric drones operating in extreme environments are very important for predicting reliability and are high-efficiency, high-performance, and lightweight power units. Multilevel inverters are suitable for application as power conversion units for stratospheric drones. A guideline is needed to evaluate whether it is suitable for practical application from a reliability perspective among various multilevel topologies. Existing reliability prediction models cannot reflect the operating characteristics of multilevel inverters. In this paper, we analyze the driving characteristics of each topology from the perspective of half-bride, which is the basic configuration of multilevel inverters, and we propose a fault tree analysis (FTA) design with three operating modes. The proposed method has the advantage of being able to easily analyze the failure rate by expanding to single-phase and three-phase and to analyze the failure rate according to changes in modulation index (MI) and power factor (PF). The failure rates of the proposed method and the part count method are analyzed using MIL-HDBK-217F. We also analyze the impact of different various operating characteristics on the failure rate. From a reliability perspective, we provide a variety of guidelines for selecting a multilevel topology that fits the operation conditions.

To Study the Changes in Power Factor & THD due to Electric Vehicle Charging

To Study the Changes in Power Factor & THD due to Electric Vehicle Charging

Analisa Kinerja Kapasitor Bank Pada Apartemen Gandaria Heights Jakarta

The occurrence of a voltage drop in the electrical panel load in the common area of ​​the Gandaria Heights apartment monitored by the Building Automation System (BAS) is caused by an erratic change in power factor (cosphi). Because according to data taken from recording through the daily logsheet, a power factor of 0.75 is obtained. Eliminating power losses in 3 phase electrical installations with a total power of 300 KVA is to improve the Power Factor against voltage drop disturbances. By adding a capacitor to the common area electrical panel which is indicated to have the lowest power factor. Based on calculations using field data, the total KVAR before and after repairs is 124 KVAR. If the existing capacitor has a value of 50 KVAR, then 3 step capacitors can be installed with a total of 150 KVAR. Thus leaving a reactive power of 26 KVAR or equivalent to 17.3% of the total power of 150 KVAR

Research on feature extraction and classification of load's reactive power based on data-driven

Driven by the advancement of science and technology, the extensive access of high proportion of renewable distributed energy and power electronic equipment has changed the reactive power characteristics of the user side of the urban distribution network. In order to deeply explore the current status of reactive power characteristics on the urban user side, this paper takes the typical users of a regional power grid in Shanghai as the research object, whose power factor data are collected, and the power factor change curves of users are analyzed by combining deep learning and multidimensional clustering. Firstly, the collected data are preliminarily processed to remove the abnormal data in the total sample, and the incomplete data is filled by the interpolation method. Then, aiming at avoiding the influence of the data with an overhigh dimension on the clustering effect, this paper uses a multi-layer autoencoder deep neural network in deep learning to reduce the dimension of the typical daily power factor change curve set of input and extracts its deep features through unsupervised learning. Finally, the K-means clustering algorithm is used to conduct clustering analysis on the daily power factor change curve of typical users with different power consumption types, including large industry, commerce, resident, and charging service industry, etc. So as to summarize various users' reactive power consumption characteristics and reactive power distribution rules. The analysis results show that the shape of the power factor curves of some users vary significantly in different months, and even the factor fluctuates greatly in the same day.

Effect of change in number and power factor of DG on optimal allocation for minimal actual power loss in RDS

Due to its remarkable techno-economic advantages, Distributed Generator (DG) penetration is growing drastically. To minimize the power losses and enhance the voltage profile, determining the precise size & position of DG is critical. The proposed paper compares the effect of variations in the number & power factor of DG on its optimal allocation in the Radial Distribution System (RDS) for minimizing the active power loss & enhancing the voltage profile using Grey Wolf Optimization (GWO) algorithm. The Direct Load Flow (DLF) approach is applied to address the system's power flow. Under altering DG parameters, the proposed method computes and compares appropriate DG allocation in standard IEEE 33 & 69 bus RDS.

Efficiency characteristics for changes in amplitude and power factor of diode‐clamped linear amplifier unequally divided voltage power supply

AbstractA diode‐clamped linear amplifier (DCLA) is proposed to realize low electromagnetic interference (EMI) caused by switching operations. A new concept of the DCLA, namely the higher efficiency unequally divided voltage power supply DCLA (DCLA‐UeDV), is proposed. In previous studies, the optimal voltage ratio was derived, and a 1.7% points improvement in efficiency was realized for a rated unity power factor load. However, it has not been examined whether the conversion efficiency can be improved, except during the rated operation. In this study, operation of the DCLA is analyzed for changes in the amplitude of the output voltage and load power factor. Then, the advantageous operating region of the DCLA‐UeDV against DCLA‐eDV is clarified.

Robust Nonlinear Controller Design for DC–AC Converter in Grid-Connected Fuel Cell System

This article presents a robust nonlinear controller for distributed fuel cell in the three-phase grid-connected system. A partial feedback linearization scheme is applied to linearize the grid-connected fuel cell system. The mismatches between the actual system and the dynamical model are considered uncertainties. The noise decoupling capability of the feedback linearized control scheme is also demonstrated. A loop-shaping-based <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{H}_\infty$</tex-math></inline-formula> mixed-sensitivity controller is designed for the partially linearized plant of the grid-connected fuel cell system. Performance of the designed controller is investigated under power factor changes, three-phase short-circuit fault, parameter variation, and measurement noise in a hardware-in-loop simulation platform with OP 4510.

저압 유도발전기에 적용되는 커패시터와 리액터의 동작에 관한 연구

Induction generators are widely used in small hydro or micro hydro power. The induction generator has a low power factor because it is an inductive load and requires reactive power required for the rotating magnetic field. Since this reactive power is not generated by itself, it must be supplied from the power source. Since most of the reactive power is provided from the power supply side, the power factor is lowered. Capacitors are added to the generator terminals to easily compensate for the lowered power factor. Inrush current occurs when an induction generator is connected to the grid. In some cases, a reactor is added to the capacitor as part of a method to reduce this inrush current. The reactor is usually connected to the generator line to reduce the inrush current, but there are cases where it is also attached to the capacitor along with the harmonic current reduction.BRIn this study, changes in inrush current, voltage drop, power and power factor were analyzed depending on whether or not a capacitor was installed and a reactor was installed on the capacitor when the induction generator was started directly and connected to the grid.

Efficiency Characteristics for Changes in Amplitude and Power Factor of Diode-Clamped Linear Amplifier Unequally Divided Voltage Power Supply

Efficiency Characteristics for Changes in Amplitude and Power Factor of Diode-Clamped Linear Amplifier Unequally Divided Voltage Power Supply

Enhancing thermoelectric performance of BaMg2-based compounds by forming solid solutions and biaxial strain

Two strategies were proposed to optimize the thermoelectric performance of BaMg2(Bi,Sb) through a solid solution method and to tune the crystal field splitting energy of orbital by using first principles calculation and Boltzmann transport theory. The increase in Sb content leads to decreased weight carrier mobility due to the changes in the electronic structure. The lattice thermal conductivity for BaMg2SbBi can be as low as 0.45 W m−1K−1, which is lower than those of other compounds. The highest ZT of ∼0.88 for BaMg2SbBi has been obtained at 750 K with n-type doping carrier concentration of −8.28 × 1018 cm−3, indicating that reaching the optimal Sb content (i.e. BaMg2SbBi) can make a significant contribution to the maximization of the ZT of n-type BaMg2(Bi,Sb) solid solutions. Adjusting the crystal field splitting energy increases the effective mass of density of states, which causes the change in power factor (PF) value and achieves a maximum PF value. When the tensile strain for BaMg2Bi2, BaMg2SbBi, and BaMg2Sb2 is 2%, 2%, and 6%, the ZT value is significantly improved, respectively. Therefore, minimizing crystal field splitting energy is also effective in the optimization of the ZT value.

역률의 변화를 이용한 유도전동기의 소프트 기동 특성 해석

Induction motors are the most widely used for loads requiring rotational force because they are self-starting, very simple construction, stronger and easier to maintain than other motors. In spite of such various advantages, a large current is generated at the time of direct-on line starting, and a voltage drop is generated. Since the voltage drop may be adversely affected by other facilities connected to the same distribution system, a start-up method is required to reduce the voltage drop as much as possible. The induction motor can select several starting methods by the capacity. Recently, a soft-start starting method using thyristors has been introduced. Induction motors have a lower power factor because the proportion of reactive power for magnetization at startup is relatively higher than the active power, but as the rotation speed increases, the power factor is gradually increased if the active power is higher than the reactive power. That is, when the power factor becomes high in a low state, the phase angle is developed from a high value to a low value. When the change of this phase angle is used at the firing angle of the thyristor, the operation change of the motor can be used as it is to reduce the starting current. In order to reduce the starting current and lower the voltage drop, the power factor change of the induction motor varying from starting to normal speed during operation is used at the firing angle of the thyristor. As a result of analysis using the power factor change of the motor as the firing angle, it is confirmed that the voltage drop is extremely effectively reduced by the reduction of the starting current.

Significant Affect of EV Charging on Grid with Renewable Technologies

While pollution is increasing as a result of greenhouse gases and global warming; the number of hybrid cars is expected to increase. Although many rechargeable cars are designed for metropolitan usages, and these cars have to be resupplied in the evening or even during the night. So the electric cars would then communicate with the grid throughout that period. This process will have an impact on the network voltage profiles as well as the loading. Established grids have been intended several decades ago, and therefore it is necessary to take note of all this whether they'll be capable of supporting one such increased loading or if there is a need for rebuilding to fulfill one such demand. Most consumers will prefer to charge at their premises during the night, which is the Low Voltage (LV) system. And it operates at 230V. The LV grid is therefore taken into account to understand the impact of charging electric vehicles. As loads are connected to different phases, there will be a phase asymmetry in the network. This asymmetry can be reduced by proper grid planning. The electrical vehicle injection into the grid will also have an impact on the power factor. As some consumers turn their electric vehicles on or off, the overall power factor changes. This has to be considered as having an impact on reactive power consumption. As the number of electric cars increases, the loading characteristics of the transformer change. The grid without the need for an electric vehicle and with an electric vehicle is considered for this work and Grid parameters are evaluated. Simulations performed in the MATLAB environment show that the driving and charging patterns of EV’s can have a substantial effect on the grid. Hence nonconventional sources with controlled charging can reduce the necessity of the import of energy from the grid.

Te-rich Bi2Te3 thin films by electron−beam deposition: Structural, electrical, optical and thermoelectric properties

Tellurium-rich Bi2Te3 thin films are deposited by electron−beam evaporation technique at 300 K. These as-deposited thin films are further annealed at 100 °C, 200 °C and 300 °C for 1 h at a pressure of 3 × 10−4 Pa. X-ray diffraction (XRD) patterns of as-deposited films distinctly show Te phase along with Bi2Te3. Peak intensity ratio suggests the polycrystalline nature of as-deposited Bi2Te3 films. On vacuum annealing Te-rich Bi2Te3 films exhibit improved crystallinity with a c-axis preferred orientation. In addition, structural features related to Te and Bi2Te3 composition change with Te fraction diminishing on annealing at 300 °C. From Raman spectral studies, the presence of distinct Te-rich regions, predominantly within the interlayers of Bi2Te3, are discerned. Te becomes structurally integrated within the quintuples of Bi2Te3 lattice as intergrown layers. Disordered planar structures, mostly concentrated on crystallite surfaces result from Te accumulations as evidenced in high-resolution transmission electron microscopy lattice images and energy dispersive X-ray spectroscopy mapping. These are consistent with the observations from XRD and Raman studies further confirming Te-rich Bi2Te3 characteristics. Electrical properties of Te-rich Bi2Te3 thin films exhibit n-type semiconductor behaviour. Seebeck coefficient for as-deposited film is ~ 32 μV/K, which increases to ~ 97 μV/K on 200 °C annealing. Resistivity increases from 1.39 × 10−4 Ωcm to 18.76 × 10−4 Ωcm and power factor changes from 7.4×10−4W/K2m to 27.17×10−4W/K2m going through a maximum at 200 °C upon systematic annealing. Te-rich Bi2Te3 thin films annealed at 200 °C exhibit high power factor (∼29×10−4W/K2m) for a wide range of temperature gradients ( ΔT from 30 °C to 165 °C).

Full compensation of reactive power in electric networks 0.4-10kV

The most important task in electric networks is to reduce energy losses. According to Network Company, in distribution electric networks with a voltage of 0.4-10 kV, they account for 62% of the total number of losses. One way to save energy is reactive power compensation. From Order of the Ministry of Energy of the Russian Federation dated June 23, 2015 No. 380 “On the Procedure for Calculation of the Ratio of Consumption of Active and Reactive Power for Individual Energy Receiving Devices (Groups of Energy Receiving Devices) of Electric Power Consumers” at a voltage of 0.4 kV, the reactive power coefficient should not exceed the value 0.35, and on the side of 10 kV - values of 0.4. In practice, in distribution electric networks, reactive power compensation devices are not installed in most cases, and the reactive power factor is 2-3 times higher than the standard values. Since compensating devices are expensive equipment, it is necessary to evaluate the feasibility of deep reactive power compensation, in the range of reactive power factor changes from its standard value to zero. The article discusses the economic and technical feasibility of deep reactive power compensation. The use of a generalized parameter of the electric network for determining the voltage at substations of distribution electric networks is proposed. The need for the coordinated use of reactive power compensation devices and booster transformers to ensure the quality of electricity is shown.

Development of Smart Grid technology for maintaining the functioning of a biogas cogeneration system

The integrated Smart Grid System of harmonization of production and consumption of electric power and heat with the use of heat-pumping power supply of the biogas plant, which uses fermented wort as a low-potential source of power, was developed. A change in the power factor of the cogeneration system, the temperature of local water is predicted by measuring the voltage at the inlet to the inverter, at the outlet from the inverter and voltage frequency. In the engine cooling circuit, the temperature of cooling water at the inlet to the heat exchanger, at the outlet from the heat exchanger, and the return water temperature are measured. It was proposed to estimate a change in the ratio of voltage at the inlet to the inverter and at the outlet from the inverter. Making forestalling decisions to change the power of the heat pump and the number of plates in the heat exchanger of the engine cooling circuit makes it possible to maintain the voltage at the entrance to the inverter and the temperature of the heated local water. The complex mathematical and logical modeling of the cogeneration system, based on the mathematical substantiation of the architecture of the cogeneration system and mathematical substantiation of the maintenance of functioning of the cogeneration system, was performed. Time constants and coefficients of the mathematical models of dynamics regarding the estimation of a change in the power factor of the cogeneration system, temperature of local water, were determined. Functional estimation of a change in power factor of the cogeneration system in the range of 85–95 %, temperature of local water in the range of 30–55 °С at the compensation of reactive power of up to 40 % was obtained. Determining final functional information provides an opportunity to make forestalling decisions on a change in the power of a heat pump and a change in the number of plates in the heat exchanger of the engine cooling circuit to maintain the functioning of the cogeneration system

An Experimental Study to Determine the Relationship Between Power Factor and Harmonic Distortion in Single-Phase AC Voltage Controller

This paper deals with the determination of the relationship between the power factor and the harmonic distortion in a single-phase AC (SPAC) voltage controller. The aim of this study is to investigate the change of power factor (PF) and total harmonic distortion (THD) during different phase triggering angles (PTA). Firstly, the advantages of using thyristor instead of triac in single-phase AC voltage controllers operating at high frequencies are mentioned. Secondly, the power factor and total harmonic distortions for single-phase AC voltage controllers are theoretically examined. Finally, the relationship between power factor and total harmonic distortion are demonstrated by both simulation and experimental studies. However, it is monitored that, at lower output voltages, the power factor (PF) is pretty much reduced and total harmonic distortion (THD) is significantly increased.

Structural Peculiarities and Thermoelectric Study of Iron Indium Thiospinel.

The homogeneity range of ternary iron indium thiospinel at 873 K was investigated. A detailed study was focused on two distinct series (y=z): 1) a previously reported charge‐balanced (In0.67+0.33y□0.33−0.33y)tetr[In2−zFez]octS4 (A1‐series; □ stands for vacancy; the abbreviations “tetr” and “oct” indicate atoms occupying tetrahedral 8a and octahedral 16d sites, respectively) and 2) a new charge‐unbalanced (In0.67+y□0.33−y)tetr[In2−zFez]octS4 (A2‐series). Fe atoms were confirmed to exclusively occupy an octahedral position in both series. An unusual reduction of the unit cell parameter with increasing Fe content is explained by differences in the ionic radii between Fe and In, as well as by an additional electrostatic attraction originating from charge imbalance (latter only in A2‐series). The studied compound is an n‐type semiconductor, and its charge carrier concentration increases or decreases for larger Fe content within the A1‐ and A2‐series, respectively. The thermal conductivity κ tot is significantly reduced upon increasing vacancy concentration, whereas the change of power factor is insufficient to drastically improve the thermoelectric figure of merit.