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Interharmonics of high frequency will cause voltage’s peak value fluctuation, which will result in flicker of fluorescent lamp and LED lamp. To realize accurate evaluation of the flicker, a method based on multiresolution S-transform is proposed to detect the voltage’s peak value fluctuation flicker. An extracting method of voltage’s peak value for “interharmonic pairs” is proposed, the principle of S-transform is introduced, and a calculation method for the peak value fluctuation flicker effect based on multiresolution S-Transform is proposed. The flicker detection platform based on the proposed method is implemented in LabVIEW, and the validity of the proposed method is testified by the simulation experiments.

The voltage fluctuation and flicker caused by the grid connection of new energy generation and the application of a large number of nonlinear and impulsive loads have become a power quality problem that can not be ignored in the current new power system. In order to extract the unsteady voltage flicker parameters, a flicker parameter analysis method based on improved ensemble local mean decomposition (ELMD) and sinc interpolation correction was proposed. The sinc interpolation method replaces the moving average interpolation in the local mean decomposition method, and an improved ensemble local mean decomposition method was constructed by using the statistical characteristics of noise. The unsteady voltage flicker signal was decomposed into a series of intrinsic mode function (IMF) components, and then the instantaneous amplitude and frequency were obtained by Hilbert transform. Aiming at the limitation of large amplitude error of flicker component greater than 12 Hz measured by local mean decomposition (LMD), an amplitude error correction model based on sinc interpolation was constructed to realize the complete detection and analysis of voltage flicker parameters. Simulation and experiments show that the improved ELMD and sinc interpolation correction flicker detection was have higher accuracy than the traditional LMD-based flicker detection method, which is less affected by the frequency fluctuation of the power grid fundamental and has strong anti-interference, and can effectively realize the accurate detection of non-steady-state voltage flicker envelope parameters. [ABSTRACT FROM AUTHOR]

One of the major challenges in grid-connected wind farms is the flicker emission caused by the reactive power extremely short time variations. A general used solution is installing a static volt-ampere reactive (VAR) compensator (SVC) as the most cost-saving device, which still holds the risk of incomplete reactive power compensation subject to the operating delay time. To this end, an accurate extreme short-term reactive power forecasting structure is essential. Although there are many studies related to the forecasting of wind power in long, medium, and short terms, however, the extremely short-term reactive power prediction of the wind farms is only addressed in few studies. The main aim in this article is to develop a method based on the convolutional neural network (CNN) to directly learn nonstationary and complex features from the raw wind farm reactive power time series and to contribute a predictive controller to mitigate the voltage flicker through an SVC connected to the wind farm. However, high sensitivity of typical mean-squared-based loss functions might lead to considerable errors in the forecasting. To resolve this issue, a modified loss function is proposed to enhance the performance and, consequently, an improved CNN is presented. The evaluation of the proposed method is based on the actual recorded data of a wind farm in Manjil, Iran. The data are directly used in the modeling of the wind farm. A current source, which is based on the actual records its amplitude and phase angle change every 0.01 s, is utilized to model the wind farm. The numerical results in terms of flicker sensation and short-term flicker perceptibility (Pst) measurement are used to verify the performance of the proposed method through comparison with the wind farm performance without SVC and SVC with a common control system. [ABSTRACT FROM AUTHOR]

There is a concern that connection of several small wind turbines may cause severe voltage fluctuation and voltage flicker in low-voltage distribution lines due to their output power variations. In this study, output power variations of four 5-kW-class small wind turbine systems were measured with an interval of 0.1 s at a site in Wakkanai, Hokkaido, and their correlations and smoothing effect in the frequency range from ~ 10 − 4 to 5 Hz were analyzed and compared with those of five residential photovoltaic power systems. The results indicate that a smoothing effect occurs more in small wind turbines than in photovoltaic systems, because of lower correlation coefficients in lower frequency ( > ~ 3 × 10 − 3 Hz) components. Voltage flicker at the point of common coupling was also measured and it was confirmed that the impact of small wind turbines on voltage flicker is low enough at the site. In addition, the upper limits of the installation number and/or the system resistance are estimated theoretically using the measured flicker values. [ABSTRACT FROM AUTHOR]

SUMMARY In recent years, rising non‐linear loads and distributed generation sources have made voltage fluctuation one of the main quality problems in power systems. To deal with this problem, new methods should be developed that can identify all flicker sources and calculate the exact contribution of each flicker source from the total voltage flicker of the network. A method with fewer measurement points is more desirable because of the less monitoring time required and cost. In this article, a new method based on wavelet transform is proposed, which can not only detect the exact location of the flicker sources but also precisely determine the contribution of each flicker source from the overall flicker value and the voltage and current flicker signals of these sources. In contrast to the previously proposed methods, which can provide only one of the mentioned pieces of information, that is, the flicker source location, the proposed method can simultaneously calculate all three of them with fewer monitoring points. The proposed method was completely simulated in MATLAB/Simulink on single‐ and multi‐flicker source systems based on an IEEE 34‐node test feeder to evaluate the method's performance. [ABSTRACT FROM AUTHOR]

Background: Pattern recognition applications have increased dramatically over the past four decades. In power system, pattern recognition can be used in fields such as power quality. One of the important power quality aspects is flicker, which is caused by torque fluctuations in wind turbines. Aims: In this paper, the various mechanical faults including single and double faults that cause flicker in vertical axis wind turbines (VAWTs) are modeled; then flicker caused by single and double faults are analyzed. Then, a novel method for pattern recognition is presented which results in more accuracy in flicker detection. Materials and Methods: In this paper, features of voltage and current signals are extracted by the 2D‐DWT. The 2D‐DWT is capable of producing valuable features than the discrete wavelet transform (DWT) at a lower level of decomposition. The 2D‐DWT is even capable of compressing data that can be suitable for smart grids, which high volume data is one of their problems. In order to reduce the redundant data, dimension of features vector, and computational burden, a new method is presented for feature selection. The backbone of the presented feature selector is the used classifier in the corresponding pattern system; so it is compatible with the classifier. Results: Results show the high accuracy of the proposed method in identifying the factors that cause flicker in VAWTs. Conclusion: In this paper, it was shown that the features extracted from the current and voltage signal by the 2D‐DWT were superior to the features extracted from the only voltage signal by the DWT. Also, the advantage of the proposed feature selection over the Relieff method was shown. [ABSTRACT FROM AUTHOR]

Summary: Reconfiguration of the distribution network (DN) is the changing of status of normally open and close switches for a specific purpose. In this paper, a situation is studied in which a fluctuating load (such as a welder) violates the network power quality (PQ) standards. Therefore, in order to mitigate the emission of the generated flicker, an optimization problem is developed for improving the PQ of the network comprising voltage flicker level and voltage profile in addition to the network power loss as a traditional objective of the DN reconfiguration. The optimization procedure is performed by changing the network configuration using tie and sectionalizing switches. Discrete particle swarm optimization is utilized to optimize the network configuration. The proposed method is evaluated in two DNs. IEEE standard 69‐bus DN and 95‐bus practical Iranian DN are considered as case study networks. The results show the effectiveness of the proposed method for improving the network PQ, especially in case of voltage flicker. The presented studies and procedure will guide the utility engineers in making decisions associated with the choice of reasonable mitigation technique to overcome the identified PQ problems. [ABSTRACT FROM AUTHOR]

Behind-the-meter solar photovoltaics (PV) have the ability to impact the distribution system due to the significant fluctuations in energy production and potential reverse power flow. While these phenomena are well understood, this research will investigate the level of solar penetration at which voltage rise and flicker are observed on a real-world distribution network. Using solar power data measured at four second intervals from the Renewable Energy and Smart Grid Laboratory at Louisiana State University alongside detailed feeder data provided by a local utility, we investigate the impact of increasing levels of solar PV penetration on voltage rise and long-term flicker. Results suggest that feeders can handle up to 10% of customers installing 7-kW behind-the-meter solar systems before voltage rise and flicker are observed. For levels above 30% penetration, feeders experience significant power quality issues. We find that the safe penetration level of a specific feeder depends on the system's topology. • The paper addresses the impact of solar growth on voltage rise and long-term flicker. • The study has been conducted on three actually existing feeders in Louisiana. • One can identify vulnerable nodes within a feeders highly penetrated by solar. • Policy considerations are discussed for future planning of power systems. [ABSTRACT FROM AUTHOR]

Summary: Dynamic power sharing among various electrical sources is a primary requirement for grid‐connected solar energy conversion system with battery storage facility (called as physical system). In this regard, adaptive solar module– and battery characteristics–based decision‐making program package is developed to guide power management activity under different dynamic operating conditions. Various multifeatures are also imposed in the package as prediction of solar condition, load forecasting capability, future generation scheduling ability, measurement of voltage flicker, and output harmonic level of solar inverter, secured communication for facilitating coordinated operation, etc. Thus, many practical issues are implemented in the package for real‐time testing of the integrated system in large‐scale under common platform, which is not noticed in published papers. Here, various codes using C# language are written in the package. The charging and discharging characteristics of battery can influence power management activity. Also, charging and discharging rate of battery can decide the life of the battery. Thus, adaptation of modified charging and discharging characteristics within power management package is proposed to cope with changed profiles of battery with its age. In addition, updating facility of solar characteristics is incorporated in the package for achieving more accurate solar prediction capability. Furthermore, real‐time compatibility of developed package with physical system model in MATLAB‐SIMULINK platform promotes research and development activity. Dynamic performances of developed package and its notable features are verified through real‐time experiments in conjunction with MATLAB‐SIMULINK software–based model of aforementioned physical system using internet‐connected multicomputer system. [ABSTRACT FROM AUTHOR]

Distributed generators connected to the power system usually produce voltage fluctuations. For wind turbines connected to a grid, large changes in wind speed can cause voltage flicker at the point of common coupling. The measurement of voltage flicker caused only by wind turbines is difficult. The wind turbine under test is usually connected to a medium voltage point, in which other fluctuating loads may produce significant voltage disturbances at the wind turbine terminal where the measurement is made. Although the IEC 61400-21-1 standard specifies a method to evaluate voltage flicker caused by wind turbines, because of the complex algorithm and process of the IEC standard, there is currently a lack of measurement equipment that meets the IEC standard. In addition, some countries that use other voltage flicker standards, such as ΔV10, do not have suitable flicker measurements for wind turbines. Therefore, this study proposes an enhanced version of the IEC 61400-21-1 standard, which integrates the ΔV10 method, so that the proposed measurement system complies with the IEC and ΔV10 standards. In this study, the voltage flicker measurement system is successfully implemented, which can help engineers to predict the voltage flicker by wind turbines and assess whether a region or grid is suitable for installing wind turbines. Therefore, it can provide wind turbine companies with a quick assessment of voltage flicker to comply with the certification process.

Declining extraction costs and process efficiencies have incented the revival of the oil and gas sector postrecession. The application of drilling rigs has been done more efficiently. These loads are very large, temporary in nature, and mobile. The drilling of each well can be done as quickly as a few hours and typically not more than a few days. These massive loads are complex to own, maintain, and operate, as a result few specialized drillers share the market. Because of the requirements for variable speed and control, drilling rigs are driven by variable frequency drives (VFDs), which are in their clear majority of older technologies such as six-pulse thyristor bridge or SCR-driven motors. These technologies are known to impose steep ramp rates (up and down) as well as rich harmonic content and variable, typically low, power factor. Furthermore, the locations of drilling rigs are typically remote, where distribution systems, if present, are weak, which lead to large background voltage distortions when such loads are present. This paper presents measurements, simulations, and analytical assessments of the characteristics and effects of harmonics and interharmonics (IHs) generated by top-drive and mud-pump VFDs in a large drilling rig operated in Alberta, Canada. Measurement results reveal very high harmonic and IH generation. To further refine the impact assessment of these harmonic emissions, the harmonic attenuation effect of the VFDs is quantified to avoid overestimating the harmonic generation of the loads. The thermal impact of the current harmonics on the coupling transformer is also quantified. [ABSTRACT FROM AUTHOR]

• Two improved types of accurate models based on the Schavemaker model are developed. • Unlike the original Schavemaker model which uses invariant parameters, the time-varying nature of the arc's parameters is considered in the proposed models. • The first improved model has time-varying coefficients. • In the second improved model, a new term has been added to the schavemaker model that includes time-varying coefficients. • A large number of the actual data are used. Electric arc furnace (EAF) is more and more applied in large industrial systems and represent one of the major sources of perturbations for the power system because it is highly non-linear and time-varying. New models are suggested in this research based on instantaneous EAF voltage and current measurements taken from EAFs at the Mobarakeh steel mill in Isfahan, Iran. This paper aims to develop two improved types of accurate models based on the Schavemaker model. The original Schavemaker model has three constant parameters. Unlike the original Schavemaker model which uses invariant parameters, the time-varying nature of the arc's parameters is considered in the proposed models. The first improved model has time-varying parameters. Additionally, to further enhance the model's accuracy, in the second improved model, a term has been added to the schavemaker model that includes time-varying parameters. Compared to the original Schavemaker model, all of the developed Schavemaker models are more precise. Finally, auto-regressive moving average (ARMA) models are used to attain the time variation characteristic of the parameters. [ABSTRACT FROM AUTHOR]

This paper presents a comparative performance analysis of squirrel cage induction generator (SCIG) and doubly fedinduction generator (DFIG) systems driven by wind turbines under different operating conditions. Also, the constantand variable-speed configurations are compared regarding short-term flicker severity, Pst. The constant speedconfigurations are based on SCIG in addition to SCIG equipped with static synchronous compensator (STATCOM)with the same generation capacity. In this paper, comprehensive models of wind turbine are used to analyze power andvoltage fluctuations. The short-time flicker index is used to assess the emitted voltage fluctuation. The effects of gridshort circuit capacity and impedance angle on flicker emission are investigated. The influences of site mean-wind-speedand turbulence intensity on voltage fluctuation are also examined. A flickermeter model is implemented according tothe guidelines provided by IEC 61000-4-15 to evaluate the severity of voltage fluctuation emission. The models ofdifferent system components along with their control schemes are simulated using Matlab/Simulink® package

This work established the error correction factor of improved Teager energy operator (TEO) to reduce the online extraction errors of complex voltage flicker envelope. The applicable rectification formulas for the amplitude and frequency of voltage flicker envelope are obtained based on the proposed method, which are extracted by improved TEO. Rife-Vincent window has been used for weighting and the spectrum results are analyzed and corrected based on improved fast Fourier transform. Based on the proposed methods, a novel online tracking of voltage flicker algorithm is established, whose efficiency and accuracy has been validated by the results of multiple simulations and applications. [ABSTRACT FROM AUTHOR]

Because of increasing requirements of the present consumers and industrial units utilizing sensitive loads, there is need of good power quality in order to retain the power quality standards. Nowadays the study of the voltage flicker is becoming essential part of power quality studies. The flicker is typically the effect of a rapidly changing load which is large with respect to the short circuit ability of an electrical supply system. The inferior effects of voltage flicker include malfunctioning of power electronic equipment. Also it causes annoying effects to human. Hence detection of the flicker source is an essential step in the power quality assessment process. This paper delivers a review about methods used to identify flicker producing loads in accordance with IEC 61000-4-15. Once the report related to the disturbance place is known, an investigation and corrective action can be accordingly carried out. Also a method based upon Discrete Wavelet Transform and Artificial Neural Network is proposed to detect initial instance of occurrence of flicker. [ABSTRACT FROM AUTHOR]

This paper introduces a method for reducing damages arising from voltage fluctuations, voltage flicker, imbalance in the three-phase and power factor reduction caused by electric arc furnaces. A novel equation is defined to calculate the susceptance values of the static var compensator control system, the active power functions of phase load as well as the reactive power ones that have been used to suppress the voltage fluctuation. By compensating the impulsive part of active power component in the impulsive loads, not only can we reduce voltage fluctuations, flicker effects, balance the system and increase the power factor, but also voltage stabilization can be directly controlled. By studying this method and simulating on Electro-Magnetic Transients Program (EMTP) software, we can see that, according to the allowable flicker limit, a compensation method can balance the system, increase power factor and resolve the problem of voltage fluctuations and flicker. [ABSTRACT FROM AUTHOR]

This paper presents a dynamic model of an electric arc furnace (EAF) developed in Matlab/Simulink environment. Model is based on simulating varying resistance of the electric arc in time-domain while taking into account its stochastic behaviour. The model was applied for estimation of voltage flicker in power transmission network at the point of common coupling caused by operation of EAF. Modelling and simulation of an International Eletrotechnical Commission (IEC) flickermeter were also performed in order to calculate voltage flicker from the simulated EAF voltage. In order to verify the developed EAF model, calculations of voltage flicker were compared to measurements obtained from various operating conditions of the EAF such as boring, melting and refining. Influence of short circuit power and switching operating condition of the transmission network on flicker levels at point of common coupling was investigated. [ABSTRACT FROM AUTHOR]

This paper deals with modeling and control of smart loads for demand-response management under increased penetration of renewable power generations (RPGs) at distribution level. The increased penetration of RPGs, particularly wind energy at distribution level, is associated with adverse impact on voltage quality. A permanent magnet synchronous generator based variable speed wind energy conversion system is modeled with a wind speed considering stochastic and periodic effects. The emulated wind power into the distribution system produces stochastic and periodic power variations. For the load demand response management, full-bridge self-commutated switches based converters are employed to control smart loads (SLs). These SLs are controlled for participating in grid bus voltage regulation and flickers mitigation. From various case studies, it is found that SLs are effective in improving the voltage profiles of the test feeder. [ABSTRACT FROM PUBLISHER]

With the increased penetration of wind power, the influence of wind turbine generators on the grid power quality stipulates careful investigation and analysis. Direct driven permanent magnet synchronous generator (PMSG) with a back-to-back converter set is one of the promising technologies in wind power generation schemes. In this paper, comprehensive models of wind turbine are used to analyze power and voltage fluctuations. The short time flicker index is used to assess the voltage fluctuation emitted. The control scheme of the grid-side converter is supported with a voltage regulation loop to reduce flicker emission. The effects of grid and site parameters on voltage fluctuation are investigated. Simulation results show that reduced flicker emissions are given when the developed voltage regulation loop is activated. Reasonable values of grid and site parameters contribute in the minimization of voltage fluctuation and flicker emission levels.

• A TEO -based PQ disturbance tracking algorithm is proposed for the voltage fluctuations with sag disturbance. • The inverter-based DG, nonlinear load and fault event influence on the voltage flicker and sag levels. • The new approach can be used to track multiple PQ disturbance with a complex structure. • This method with proper accuracy can track the voltage amplitude variations in the presence of notch and harmonics. This paper presents an optimal algorithm for simultaneous tracking of power quality (PQ) events in distribution systems in the presence of the inverter-based distributed generation and nonlinear load. The algorithm is based on Teager Energy Operator (TEO). The main specification of the Teager Energy Operator, compared with the commonly used methods in the literature, is the simplicity of its mathematical. Using a proposed method, a suitable combination of the TEO and a relevant filter set is defined as a criterion to reduce envelope ripples and improve a suitable tracking for the power quality disturbances. This approach is able to accurately detect the distortions and sudden changes of voltage under different conditions. The paper considers the voltage fluctuations and voltage sag at the point of common coupling (PCC) and nearby points of the PCC as these voltage disturbances. Extensive simulations for the several power quality disturbance signals and the distribution network based on nonlinear elements using the new approach are performed and performance evaluation is clearly distinguished from the results. Simulation results for single and multiple power quality disturbances present that the proposed method is precise and suitable in detecting voltage disturbances. [ABSTRACT FROM AUTHOR]

This paper deals with the Major Power Quality problems like Voltage Flicker (VF) that occurs in a Power Industry. Industrial Arc Furnace (IAF) is the vital source for producing VF. It creates most significant Disturbance in electrical power systems dominantly in Distribution systems. The fast response of Custom Power device makes it a better solution for improving Power Quality in Distribution systems against the Non-linear loads like IAF. Due to the fastest growth in Semi-Conductors Industry and modern Techniques for development of Voltage Source Converters (VSC), FACTS Devices are used for Voltage Flicker Mitigation. The Voltage Flicker Compensation is done in 3 stages and analyzes the related results. Initially the Voltage Flicker mitigation using FCTCR (Fixed Capacitor Thyristor Controlled Reactor) was simulated. Secondly, the compensation for the Static Synchronous Compensator (STATCOM) has been performed. This paper presents a Instantaneous Reactive Power Controller technique for 6-pulse STATCOM to effectively compensate voltage flicker due to electric arc furnace load. In these cases, some major harmonic components are presented in the system, which can be minimized by using 12-pulse STATCOM. The obtained results show that STATCOM is an efficient solution for the Voltage Flicker Compensation. All the Simulations are done in the MATLAB Software. [ABSTRACT FROM AUTHOR]

Electric Arc Furnaces (EAFs), widely used for steel production industries, are highly nonlinear time-variant disturbing loads because of the random change of the electric arc length results in arc voltage and furnace/supply current fluctuations. Consequently, Power Quality (PQ) problems such as undesirable variations of reactive power, poor power factor, harmonics, and voltage flickers may appear. The main objective of this paper is to provide the wavelet transform method for EAF to perform particular studies for Voltage Flicker Recognition. For this purpose, the mathematical equations and the dynamic model of the EAF voltage flicker are developed. Both Discrete Wavelet Transform (DWT) and Continuous Wavelet Transform (CWT) are employed to detect flicker fluctuations, estimate its duration, magnitude to eliminate the expected fluctuations. Despite nonlinearities and harmonics often encountered in EAFs, a comprehensive comparison between DWT and CWT approaches are exhibited towards enhancing PQ problems. Simulations results, via MATLAB™/Simulink, reveal that the proposed Daubechie's DWT can be successfully used for ensuring significant decision for flicker compared to the Daubechie's CWT approach. It is evident to mention that, the results of this study open the way to explore a new standard based on Wavelet Transform (WT) for voltage flicker recognition. [ABSTRACT FROM AUTHOR]

In this article, an approach based on empirical mode decomposition (EMD) is suggested in order to calculate short-term icker severity, Pst, in power systems. EMD is a new signal processing method used for the analysis of nonlinear and nonstationary signals. Pst is an important quantity in the electric power quality index defined by the International Electrotechnical Commission. In the suggested approach, the voltage signal is separated into intrinsic mode function components using EMD. These components are used for calculating the voltage icker amplitude and frequency, and Pst is calculated as a result of the statistical evaluation of icker amplitude. EMD is thought to be efficient in finding the ickers and calculating Pst due to power to find the changes in the oscillating signal envelope of EMD. Simulations are made using an input signal modulated with single and multiicker frequency. Simulations show that the approach is usable in the calculation of Pst and it gives good results. [ABSTRACT FROM AUTHOR]

Effective estimation of voltage flicker components plays an important role in distribution systems for either flicker meters or flicker compensators. A novel approach has been presented in this paper to accurately estimate voltage flicker components by using the improved Teager energy operator (ITEO) and the improved chirp-Z transform (ICZT). The error correction factor K of the Teager energy operator is presented and ITEO is established to reduce the extraction errors of voltage flicker waveform. ICZT is used to extract the frequency and magnitude of the voltage envelope which is corrected by the K factor of ITEO. The effects of signal sampling rate, sampling number, spectrum subdivision points of ICZT, voltage harmonics and interharmonics, frequency fluctuation, and white noise are investigated. The implementation of the proposed approach in the digital-signal-processor platform is also introduced. Multiple simulation and experimental test application results validate the accuracy and efficiency of the proposed approach. [ABSTRACT FROM PUBLISHER]

The emerging trend for electric utilities to install wind-based generation on a large scale into distribution networks, employing a doubly fed induction generator or full-converter turbine technologies is raising issues for distribution planning engineers with regard to flicker among other power-quality (PQ) issues. This paper investigates dynamic volt/var control, a viable flicker mitigation technique which exploits the reactive power capabilities of modern power-electronic interfaced wind turbine generators. Dynamic volt/var control essentially mitigates flicker by solely dispatching reactive power based on voltage fluctuations within the flicker frequency band. This technique can be incorporated as part of a wind farm multiobjective reactive power-control scheme, which facilitates regulating: 1) the voltage level at the point of common coupling (PCC), employing slow-acting voltage control or power factor control and 2) the flicker level at the PCC with fast-acting dynamic volt/var control. This two-level approach can reduce the wind farm flicker level up to 80% and maintains the voltage level at the PCC well within acceptable bands. The results presented in this paper focus on a typical 25-kV medium-voltage distribution feeder integrating wind-based generation on a large scale. The performance of the two-level controller was tested for varying levels of penetration and wind speed conditions. The applicable standards and utility grid-code requirements are considered throughout. [ABSTRACT FROM PUBLISHER]

· A novel improved square demodulation method based on analytic mode decomposition is proposed to quickly extract the time-varying flicker envelope signals. · The adaptive variational mode decomposition is used to analyze the flicker envelope parameters which avoids the mode-mixing confusion effectively. · A time-varying voltage flicker parameter detection system is developed and implemented in a PXI platform, using LabVIEW. Time-varying voltage flicker caused by non-linear and fluctuating loads have adverse impact on the power grid and lighting equipment. This paper proposes a time-varying voltage flicker analysis method based on analytic-adaptive variational mode decomposition (AAVMD). A novel improved square demodulation method based on analytic mode decomposition (AMD), is proposed to quickly extract the time-varying flicker envelope signals, which simplify the computational process of voltage flicker without the analog filter. Then, the adaptive variational mode decomposition (AVMD), using the energy loss coefficient and energy difference as a criterion for determining the number of modal decompositions, is proposed to detect the time-varying voltage flicker envelope which effectively avoids the pattern confusion problem of Hilbert-Huang transform (HHT). The accuracy and validity of the proposed method are demonstrated in a National Instrument-PXI system under the conditions of single frequency flicker modulation, time-varying flicker modulation magnitude, multi-frequency flicker modulation, fundamental frequency deviation and white noise interference. [ABSTRACT FROM AUTHOR]

In order to realize the accurate detection of voltage flicker, this paper proposes the analysis method based on LMD, the method which decompose complicated multi-component signal into the linear combination of some production functions, and works out the time-frequency distribution of original signal by the combination of transient time frequency and amplitude of PF component. Firstly, LMD decomposition for voltage flicker is made, the transient amplitude component got from which is used to determine the amplitude of voltage flicker. Hilbert transform for the obtained pure frequency regulation signal is made to calculate transient frequency, the catastrophe point of which is used to locate the start-stop time for voltage flicker. The result of simulation proves the accuracy and feasibility of LMD in voltage flicker analysis. [ABSTRACT FROM AUTHOR]

In order to realize the accurate detection of voltage flicker， this paper proposes the analysis method based on LMD， the method which decompose complicated multi - component signal into the linear combination of some production functions， and works out the time - frequency distribution of original signal by the combination of transient time frequency and amplitude of PF component. Firstly， LMD decomposition for voltage flicker is made， the transient amplitude component got from which is used to determine the amplitude of voltage flicker. Hilbert transform for the obtained pure frequency regulation signal is made to calculate transient frequency， the catastrophe point of which is used to locate the start - stop time for voltage flicker. The result of simulation proves the accuracy and feasibility of LMD in voltage flicker analysis. [ABSTRACT FROM AUTHOR]

Voltage flicker is a non-stationary waveform for which direct spectral analysis is not appropriate. To overcome this difficulty, a Hilbert–Huang transform based technique is proposed here. Hilbert–Huang transform is a new signal processing method that can be used in the analysis of non-linear and non-stationary signals. In the suggested method, the recorded voltage signal is decomposed into Hilbert–Huang transform components, namely the empirical mode decomposition and intrinsic mode function components. These components are used in the calculation of the frequency and amplitude of voltage flicker. The clear success of empirical mode decomposition in depicting envelope variations of a sinusoidal waveform has been the main motivation for the adoption of Hilbert–Huang transform in flicker analysis. Simulations are performed over waveforms, including single- and multiple-flicker frequencies and flicker with harmonic, voltage sag, and voltage swell. The waveforms are selected as pure sinusoids, as well as harmonically rich voltage waveforms. Simulation results show that the proposed methodology constitutes a plausible way to analyze voltage flickers, making it an alternative to the available flicker analysis tools. [ABSTRACT FROM PUBLISHER]