Voltage Quantities Research Articles

Power Components Mean Values Determination Using New Ip-Iq Method for Transients

This paper deals with the quasi-instantaneous determination (in a single-step response time) of apparent, active, and reactive (i.e., blind and distortion) power mean values including the total power factor, total harmonic distortion, and phase shift of fundamentals of a power electronic and electrical system (PEES) using the ip-iq method, which is the main contribution of the paper. The power components’ mean values are investigated during the transient and steady states. The power components’ mean values can be determined directly from phase current and voltage quantities, using an integral calculus over one period within the next calculation step and using moving average and moving rms techniques (or digital filtering). Consequently, the power factor can be evaluated with known values of a phase shift of fundamentals (using a Fourier analysis). The results of this study show how a distortion power component during transients is generated even under a harmonic supply and linear resistive–inductive load. The paper contains a theoretical base, modeling, and simulation for the three and single phases of the transients in power electronic systems. The worked-out results can be used to determine and size any PES. The presented approach brings a detailed time waveform verified by simulations in Matlab/Simulink 2022a and the Real-time HW Simulator Plecs RT Box 1.

Time domain modeling of constant power loads for electromagnetic transient simulations

This paper proposes a dynamic constant power load offering constant active and reactive power and constant power factor suitable for electromagnetic transient simulations. The proposed model is agnostic to the frequency components of the system because it is developed in the time domain. The proposed model returns current and voltage quantities imitating the behavior of either inductive or capacitive loads. The model is customized so that it can be solved using readily available numeric solvers, such as branch-and-bound algorithms. The bottleneck of the computational speed depends on the numeric solver that is employed to solve the proposed model and the hardware used to process the computations. Also, convergence to a solution (an issue associated with every solver) is more likely to occur if the optimum initial solution is provided, which is left for future research. The model is validated using constant impedance load data. In this work, 2500 data points were simulated, and the output shows that the proposed model is accurate, and any approximations can be attributed to the adopted numerical differentiation method. The model is computationally exhaustive; thus, its application is limited to small systems.

Modelling and design of grid voltage oriented vector control scheme for DC railway recuperating system

The braking energy harvested by a railway vehicle can be restored to the utility grid with a power recuperating system. A grid connected voltage source inverter (VSI) is commonly used as a grid-feeding converter in the recuperating system. This paper proposes to integrate grid voltage oriented vector control (GVOVC) and third harmonic voltage injection pulse width modulation (THVI-PWM) technique for the VSI to ensure grid voltage and frequency synchronization. A simulation study is carried out to evaluate the feasibility of the proposed control and modulation schemes using MATLAB/Simulink. The results show that the proposed controller may reach steady-state operating mode within 7 ms by producing good quality AC voltages and currents waveforms. With the independent control of voltage quantities in dq reference frame, the regulation of active and reactive power could be realized.

Single-Step Response and Determination of Power Components Mean Values of PES Using p-q Method during Transients

This paper deals with the quasi-instantaneous determination of an apparent-, active-, and reactive (i.e., blind and distortion) power mean values, including total power factor, total harmonic distortion, and phase shift of fundamentals of power electronic system (PES) using the p-q method. The power components’ mean values are investigated both during transients and steady states. Using an integral calculus over one period and the moving average method (or digital filtering), the power components’ mean values can be determined within the next calculation step directly from phase current and voltage quantities. Consequently, with known values of a phase shift of fundamentals (using Fourier analysis), the power factor can be evaluated. The results of this study show how a distortion power component during transients is generated even under harmonic supplying and linear resistive-inductive load. The paper contains a theoretical base, modeling, and simulation for the 5-, 3-, and 2-phases of PES transients. A system compensated by switched capacitors as well as an active power filter shows a possibility to compensate for distortion and reactive power components in the next calculation step. Worked-out results can be used for the right determination and sizing of any PES. The presented approach brings the detailed time-waveform and improved quality of electrical quantities (time-waveforms), and through quasi-instantaneous (single step) response time of compensation, minimizes nascent overvoltage of the system.

Stability Analysis of Two Power Converters Control Algorithms Connected to Micro-Grids with Wide Frequency Variation.

Distributed power generation, micro-grids, and networks working in islanding mode have strong deviations in voltage quantities. These deviations can be divided into amplitude and frequency. Amplitude deviations are well-known and studied, as they are common in small and big grids. However, deviations on the ac mains frequency have not been widely studied. The literature shows control schemes capable of bearing these variations, but no systematic analysis has been performed to ensure stability. As the majority of power converters are designed for big grids, their analysis and design neglect frequency disturbances, therefore those devices allow a very small frequency operating window. For instance, in power converters that need to be synchronized to the grid, the standard deviation does not go beyond 0.5 Hz, and for grid-tied inverters it does not go beyond 1 Hz, whereas variations of around 8 Hz can be expected in micro-grids. This work presents a comprehensive analysis of the control system’s stability, where two different control schemes for a back-to-back static converter topology are implemented and studied under a wide variable grid frequency. Because the behavior of power converters is nonlinear and coupled, dynamic and static decouplers are usually introduced in the controller, being a key element on the scheme according to the findings. The results show that using just a static decoupler does not guarantee stability under frequency variations; meanwhile, when a dynamic decoupler is used, the operating window can be greatly extended. The procedure shown in this paper can also be extended to other control algorithms, making it possible to carefully choose the control system for a variable frequency condition. Simulated and experimental results confirm the theoretical approach.

Flexible, Multifunctional Micro-Sensor Applied to Internal Measurement and Diagnosis of Vanadium Flow Battery.

The vanadium redox flow battery (VRFB) system is an emerging energy storage technology with many advantages, such as high efficiency, long life, and high safety. However, during the power-generation process, if local high temperature is generated, the rate of ions passing through the membrane will increase. In addition, it will also cause vanadium pentoxide molecules (V2O5) to exist in the solid state. Once the solid is formed, it will affect the flow of the vanadium electrolyte, which will eventually cause the temperature of the VRFB to continue to rise. According to the various physical parameters of VRFB shown in the literature, they have a significant impact on the efficiency and life of VRFB. Therefore, this research proposes to develop flexible multifunction (voltage, current, temperature, and flow) micro-sensors using micro-electro-mechanical systems (MEMS) technology to meet the need for real-time micro-diagnosis in the VRFB. The device is embedded in the VRFB of real-time microscopic sensing and diagnosis. Its technical advantages are: (1) it can simultaneously locally measure four physical quantities of voltage, current, temperature, and flow; (2) due to its mall size it can be accurately embedded; (3) the high accuracy and sensitivity provides it with a fast response time; and (4) it possesses extreme environment resistance.

Universal Measuring Unit for High Voltage Measurements

Traditionally, high voltage (HV) laboratories have required different measuring instruments to measure alternating voltages 50/60 Hz (AC), using peak voltmeters, lightning impulses, through peak voltage meters or oscilloscopes and the apparent charge, by means of partial discharge (PD) measuring instruments. All of them with very different technical requirements stablished in applicable hardware and software standards (IEC 61083 series [1], IEC 60060 series [2, 3] and IEC 60270 [4]). However, the technological evolution of measuring instruments has allowed these measurements could be carried out through highperformance digital recorders. This article describes a new universal measuring instrument, developed by the LCOE for high voltage quantities, known as UMU (Universal Measuring Unit), for the five typical measurements to be carried out in any high voltage laboratory: AC 50/60 Hz, DC, Lightning impulse 1.2/50 μs (LI), Switching impulse 250/2500 μs (SI), partial discharge measurements, Radio Interference Voltage (RIV) measurements, transmitted overvoltage in secondary winding of voltage and current measuring transformers.A new software package has been also developed in the framework of 19NRM07 HV-com2 project [5].

ANALISIS TIMBANGAN PADA HOTPLATE MANGNETIC STIRRER BERBASIS ARDUINO UNO

Hotplate magnetic stirrer is a tool used to homogenize and heat a solution, this tool is used in microbiology, chemistry and pharmaceutical laboratories to homogenize and heat a solution. The main component of the hotplate magnetic stirrer is the stepper motor which functions to rotate the sample and heat it using a heater at a predetermined speed and time. The hotplate magnetic stirrer that the author made uses an Arduino uno At mega 328p microcontroller, a motor driver, a 20x4 LCD, a buzzer and a keypad. the motor driver is used to adjust the motor speed according to the user's wishes, the LCD functions to display the motor speed and timer, the buzzer will sound when the magnetic stirrer hotplate is turned on and when the keypad is pressed, the loadcall functions as a sensor used to detect the pressure that is placed on the plate , the HX711 module functions to convert measured changes in resistance changes and convert them into voltage quantities through existing circuits, keypads as speed and timer inputs. When the speed has been reached, the motor driver will work to control the motor to keep it according to the desired speed.

Improved generator circuit breaker failure protection method combined with voltage quantities

Safe and reliable generator circuit breaker (GCB) failure protection can ensure effective isolation between generator and system under different fault conditions to avoid generator damage. In this paper, aiming at the existing problems of the GCB failure protection criterions based on current quantities, the voltage quantities are combined to constitute the improved GCB failure protection. Through fault sequence network analysis, it is concluded that there are voltage phasor differences between the two sides of GCB for the normally separated phases, while the values are zero for the rejected phases. On this basis, a GCB failure protection criterion based on the voltage phasor difference is proposed for the generators equipped with PTs at the two sides of GCB. After a generator fault occurs, in the process of de-excitation, the terminal voltage drops quickly except GCB three-phase rejection because of the voltage support from the system side. Moreover, under the GCB three-phase rejection situation, the loads cannot be effectively shed and no terminal voltage increase is caused compared with other GCB operation situations. Thus, the protection criterions based on the voltage variation are proposed to distinguish GCB three-phase rejection situation, including the voltage changing rate criterion and the increased voltage mutation criterion. They are used for generators equipped with only one terminal PT. Simulation results of PSCAD/EMTDC verify the effectiveness of the proposed methods.

Improved MRAS Rotor Position Observer Based on Control Winding Power Factor for Stand-Alone Brushless Doubly-Fed Induction Generators

The main contribution of this study is to propose a new rotor position observer with the approach of model reference adaptive system (MRAS) associated with the quantity of control winding (CW) power factor of the brushless doubly-fed induction generator (BDFIG) for sensorless voltage control target in stand-alone systems. The proposed observer relies on the field-orientation scheme of power winding (PW) side. The proposed sensorless methodology does not need any computation process with integration for obtaining the flux components. In addition, the new methodology can reduce the voltage sensors required for detecting the actual CW voltage quantities to be used in the calculations process of the proposed MRAS procedure by directly realizing the CW reference stationary voltages from the input path of SVPWM. This would ensure the simplicity of the suggested procedure for detecting the rotational position of the generator. The stability confirmation of the presented estimation method is analyzed and realized with the aid of technique of hyperstability concept and aided with the criteria of Popov's analysis. Moreover, the verification of robustness for the proposed observer is studied via uncertainty issues of machine parameters. Comprehensive simulation and experimental results are carried out to verify this method,

Impact of Resistive SFCLs on Superimposed Quantities in Power System Faults

Superimposed quantities, also known as delta quantities, are the transient signatures of fault currents and voltages that can be utilized by protective relays to achieve fast fault detection for electric power grid applications. With the installation of superconducting fault current limiters (SFCLs) on power transmission lines, the profiles of superimposed quantities in power system faults are affected due to the altered impedance properties at transmission line terminals, which may further affect protective relay performance. In this article, we investigate the impact of a resistive SFCL on superimposed quantity profiles. The equivalent circuit of a resistive SFCL connected to an electric power transmission system is first illustrated based on which the simulation model is established in an electromagnetic transients program. Various types of power transmission line faults are simulated. The superimposed current and voltage quantities at transmission line terminals are obtained. The simulation results demonstrate that the acquired superimposed quantities are significantly affected by the SFCL. Possible consequences to protection functions are discussed.

Mitigation of Harmonics and Unbalanced Voltage Disturbance Compensation by MSVPWM Based- DVR in the Distribution Net

Recent power distribution networks comprise abundant sensitive loads, which extremely impact the power quality of source in electrical power networks. Voltage dip, voltage rise, imbalanced voltage, line notching and distortion of harmonics are problems of power quality frequently take place. Pre-disturbance voltage compensation strategy and phase-locked-loop (PLL) based dq- space vector control are presented to improve a Dynamic Voltage Restorer (DVR), which restore the magnitude of voltage disturbance and displacement of phase angle to prior of voltage disturbance. 3-phase Multilevel strategy of Space Vector Pulse Width Modulation (MSVPWM) based- Multilevel Diode Clamped Converter (MDCC) is proposed as switching pulse signals employed low frequency, which creates high levels of voltage and fewer harmonics in the output waveform in comparison to 2-level SVPWM based- DVR. 3-level SVPWM based- DVR under balanced and imbalanced distortion voltage disturbances included sags and swells injected appreciated quantities of voltage, thereby attained ideal sinusoidal waveform with lower Total Harmonic Distortion THD% compared to 2-level SVPWM based- DVR. Furthermore, real and imaginary powers balanced effectively at sensitive load during various distortion voltage disturbance conditions via presented work. The proposed simulation model of multi-level SVPWM based- DVR is implemented by dedicating the software system of MATLAB/SIMULINK. The results of simulation exhibit the effectiveness and efficiency of the presented work under different distortion voltage disturbance conditions.

Comparison of testing load cell sensor data sampling method based on the variation of time delay

Load Cell Sensors are transducers (transducers, electronic components that can measure physical quantities into electrical signals) that can convert the pressure by the load into an electrical signal. IC HX711 is a weighing module, which has a working principle of converting the measured changes in resistance changes and converting them into voltage quantities through the existing circuit. Load cell and HX7411 are used to obtain data of weight which will be compared with a commercial digital weight scale that the accuracy has been verified. In collecting data of weight, there are several calculation methods including the mean, modus, and median method. This study aims to provide test results for the three methods with different variations in delay. Delay is used to avoid errors in taking data from the sensor directly and also to provide pauses for the sensor in real time data collection. The test was conducted with four human subjects who have differences in body weight. The variation of delay used is 250ms, 500ms, 750ms, and 1000ms. The test results show that when testing variations in body weight with a delay time of 250ms, the mean method has the best results with a value of nmean = 2. In the 500ms delay test, the median method has the best results with the value nmedian = 3. In the 500ms delay test, the mean and median methods have the same good results with values of nmean = 2 and nmedian = 2. In the 1000ms delay test, the median method has the best results with a value of nmedian = 2. The results of the whole test show that the values of Nmean = 6, Nmedian = 8, and Nmodus = 2 which indicate that the median method is the method that has the best level of precision.

Influence of restricted operating space on the performance of random vibration energy harvesting

The ambition to create self-powered microscale electrical devices motivates scientific and industrial communities to investigate the energy harvesting technique, especially working in random vibration circumstances. The mechanical response of the random vibration system may approach infinity with small probability, and then the restricted operating space of the energy harvesting system will unavoidably induce the occurrence of collision interaction. Here, the random mechanical vibration and electrical output of the vibration energy harvesting system including inelastic collision are investigated, in which the random excitation is described by Gaussian white noise, while the collision interactions are described by the transient impact model and inelastic contact model, respectively. Introducing the generalized harmonic transformation of mechanical states and adopting a slow-varying process assumption of amplitude and averaged frequency, the output voltage can be explicitly expressed as the function of displacement, velocity, and system total energy by directly integrating the linear electrical equation. The transient impact interaction is equivalent to an effective damping with energy-dependent damping coefficient, while the inelastic contact interaction is equivalent to an effective damping and an affiliated potential energy. The averaged equations with respect to mechanical energy are then derived through the stochastic averaging technique. The stationary probabilistic density function of mechanical states is established by solving the reduced Fokker–Plank–Kolmogorov equation, and then the statistical quantities of electrical voltage are obtained by the relation between voltage and mechanical states. The effectiveness and precision of the analytical procedure are validated through the results from Monte Carlo simulations, and the influence of collision interaction on the performance of energy harvesting is discussed in detail. Also, for the energy harvesting system excited by colored noise, the influence of collision interaction on the performance is evaluated through Monte Carlo simulations.

Dynamic Performance Enhancement of Single-Phase and Two-Phase Enhanced Phase-Locked Loops by Using In-Loop Multiple Delayed Signal Cancellation Filters

The estimation of phase-angle, frequency, and amplitude are vital for the control of grid-connected power electronic systems in both single-phase and three-phase systems. The single-phase enhanced phase-locked loop (1P-EPLL) and two-phase enhanced phase-locked loop (2P-EPLL) techniques can be used to estimate single-phase and three-phase grid voltage quantities, respectively. However, under the presence of harmonics, unbalance, and dc offsets, the estimated quantities by these enhanced phase-locked loops (EPLLs) may contain periodic ripples. These periodic ripples are eliminated by using multiple delayed signal cancellation (MDSC) filters in the phase-angle estimation loop and amplitude estimation loop of these EPLLs. To improve the dynamic responses of MDSC-based EPLLs, proportional-integral (PI) controller is replaced with a proportional-integral-derivative (PID) controller. The design guidelines for choosing the control parameters are provided. The MDSC filters in the EPLLs are realized both in direct-form and recursive-form structures. The proposed EPLLs are verified experimentally by using real-time system and compared with recent advanced EPLLs.

Recursive Implementation of Multiple Delayed Signal Cancellation Operators and Their Applications in Prefiltered and In-Loop Filtered PLLs Under Adverse Grid Conditions

Phase-locked loops (PLLs) are widely utilized for grid synchronization and control of power electronic converters. More recently, both in-loop-filtered- and prefiltered-based PLLs have become more popular due to their prompt and accurate estimations of grid voltage quantities. In the past, an advanced filter viz., multiple delayed signal cancellation (MDSC) operators, has been successfully investigated in both $\alpha \beta$ -frame and $dq$ -frame for extracting fundamental-frequency positive-sequence grid voltage quantities by using conventional synchronous reference frame PLL. These operators can provide more flexibility to configure the delay time and undesired harmonics in comparison with the existing cascaded delayed signal cancellation operators. In this paper, the recursive-form structures of MDSC operators are analyzed, which are derived from the direct-form MDSC realizations. The recursive-form structures of MDSC operators are simple in implementation when compared to direct-form realizations. With the recursive-form MDSC implementations, both prefiltered MDSC-PLL and in-loop filtered MDSC-PLL will be investigated in detail. The design guidelines of these recursive-form-based MDSC-PLLs are presented. Comparison studies of the proposed PLLs and the validation of their dynamic performances are done by experimental verifications.

Diagnostic approach in assessment of a ferroresonant circuit

This paper presents possibilities offered by a diagnostic system called FeD. The system is completely original; it has been developed by the authors on the basis of Arduino platform. The system has been designed to perform and record measurements and to carry out different numerical operations. The real-time function for several operations is incorporated in this system. The necessary input data for the system consist of the electrical voltage waveforms only. Rescaled voltage quantities can be displayed, measured, recorded or computed in any chosen way. The system has been developed particularly for measurements and computations in the ferroresonant circuits. The strongest part of the system is its versatility. It works with a standard PC and supports a universal connection (USB standard). This is undeniably a cost-wise solution. Driving and control of the system functions are carried out using the authors’ original software implemented in SciLab environment. This is free software, similar to and compatible with other existing CAD programs such as Octave and MATLAB. The obtained data, scripts and results can be freely transferred between them. The program is equipped with a transparent GUI. The need of constructing a special system to diagnose the ferroresonant circuit has emerged during earlier ferroresonance analyses and computations. Every ferroresonant circuit requires specific kind of diagnostics to estimate and display its base features in order to determine the best scientific approach to the problem. The ferroresonance phenomenon belongs to the domain of nonlinear problems. Its analysis requires excellent skills in mathematics and physics as well as computer science. Moreover, this subject also requires specialized engineering knowledge, particularly in the field of power engineering and power system equipment. Modern mathematical models and analyses used in ferroresonant computations are quite accurate; however, in case of a common user, they are often difficult to understand or implement. This paper provides full description of construction, features and test results of the developed hardware/software system designed for diagnostics of ferroresonant circuits. The test circuit case study has been performed in the entire power supply range. Results of measurements and computations as well as screenshots captured from authors’ original software are shown in different figures. The developed software and recorded data have been finally used in modeling and further simulations. During this, the application of the fractional derivative iron core coil model to ferroresonance analysis has been shown. The waveforms obtained from computer simulations have been compared with those obtained from measurements performed in the test circuit.

A Comprehensive Review of Field-Oriented Control in Sensorless Control Techniques for Electric Vehicle

This paper is written to give a complete comprehensive analysis on sensorless Field-Oriented Control (FOC) in electric vehicle motor application. Sensorless control has opened a wide discussion in terms of its low cost and less complexity for crucial applications such as in electric vehicle, where rotor speed can be estimated by measuring the quantities of stator voltage and current at the terminal of the motor. Therefore, this paper provides a comprehensive review of the control methods for sensorless motor in order to increase motor efficiency. This review is based on vector control, which is the main focus in this paper, and on how it can be used more effectively in a wide speed range. Several tabulated tables are presented in order to give a fair comparison in determining the advantages of sensorless application of FOC in the estimation method for flux and speed controls. These tables show the effectiveness of each vector control in order to achieve the FOC. Lastly, the authors estimate the error, torque ripple and efficiency of the motor in order to allow readers to choose a suitable sensorless control for an effective method to increase the efficiency of an electric vehicle.

Impedance‐based pilot protection for ultra‐high‐voltage/extra‐high‐voltage transmission lines

Current differential protection is one of the major protections for extra-high-voltage/ultra-high-voltage transmission lines, but its performance is severely weakened by the prominent capacitive charging current along transmission lines. Travelling waves take the charging current into account inherently, hence travelling wave-based protection is not impacted by the charging current. Based on the principle of travelling waves, this study proposes the concept of integrated surge impedance (ISI), which is defined as the ratio of the difference of voltage quantities at two ends of a line to the sum of current quantities at two terminals of the same line. The ISI, closely related to travelling wave differential current, can discriminate between internal and external faults clearly. The ISI-based criterion is composed of power frequency quantities in order to ensure the robustness of the protection. The action zone is designed on an impedance plane. EMTP simulation verifies the correctness of the proposed pilot protection.

PARAMETERS IDENTIFICATION OF THREE-PHASE TO CONTINUOUS CURRENT SYSTEMS DEVICES BY THE TIME SERIES METHOD

Purpose. The scientific work provides for the development and justification of a new method for the parametric identification of electric traction devices based on a system of orthogonal functions, namely – on the basis of time power series. Methodology. To solve this problem, we use: the theory of power series; basic laws of theoretical electrical engineering, elements of the spectral analysis of periodic and non-periodic non-sinusoidal functions of electrical quantities of voltage and current; matrix methods for solving a system of algebraic equations. Findings. A new method of time power series is developed, which can be used to identify devices both traction power systems and electric rolling stock. The method is based on the compilation of integro-differential equations of the electromagnetic state of the electrotechnical system under study. The given voltage and current in the indicated equations are approximated by power series, into which the required parameters of the electric circuit of the system enter in the form of coefficients. Using the developed method, electric locomotives AC of DSС3 and 2ES5K were identified in the work. Their parameters R and L, varying in time over the period of the applied sinusoidal voltage, are determined. Time dependences R(t) and L(t) are constructed and analyzed. An explanation is given for the regions with negative inductance. It is shown that these electric locomotives can be identified by a passive two-terminal network with parametric resistive and inductive elements. Originality. Innovation of work consists, first, in development of a new method of identification, and secondly, in the possibility of replacing any device of electric traction with parameters of RL- a two-terminal network. And, finally, the fact that the proposed method makes it possible, by improving the approximation of input and output voltages and currents, to obtain the most accurate values of the parameters R and L the identification two-terminal network. Practical value. The developed method makes it possible to evaluate the parameters of devices of electric traction systems on a real-time scale, which facilitates its application in modeling the transient electromagnetic processes that arise during the operation of the system under study in emergency modes.