The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Juan C. Vasquez - One of the best experts on this subject based on the ideXlab platform.

  • performance improvement of shunt active power filter based on non linear least square approach
    Electric Power Systems Research, 2018
    Co-Authors: Yacine Terriche, Josep M. Guerrero, Juan C. Vasquez
    Abstract:

    Abstract Nowadays, the shunt active power filters (SAPFs) have become a popular solution for power quality issues. A crucial issue in controlling the SAPFs which is highly correlated with their accuracy, flexibility and dynamic behavior, is generating the reference compensating current (RCC). The synchronous reference frame (SRF) approach is widely used for generating the RCC due to its simplicity and computation efficiency. However, the SRF approach needs precise information of the voltage phase which becomes a challenge under adverse grid conditions. A typical solution to answer this need is the application of advanced phase locked loops (PLLs). The PLLs are closed-loop control systems that often have a response time more than two cycles of the Nominal Frequency. Besides, a special care should be paid in designing their control parameters to ensure their stable operation in all circumstances. This paper proposes an improved open loop strategy which is unconditionally stable and flexible. The proposed method which is based on non-linear least square (NLS) approach can extract the fundamental voltage and estimates its phase within only half cycle, even in the presence of odd harmonics and dc offset. The performance of the proposed method is verified under MATLAB/Simulink environment and validated experimentally and compared with advanced PLLs.

  • matrix pencil method based reference current generation for shunt active power filters
    Iet Power Electronics, 2018
    Co-Authors: Yacine Terriche, Saeed Golestan, Josep M. Guerrero, Djallel Kerdoune, Juan C. Vasquez
    Abstract:

    In recent years, the shunt active power filters (SAPFs) have received much attention for compensating the harmonic pollution and also providing the reactive content. A crucial issue in controlling the SAPF is generating the reference compensating current (RCC). Typical approaches for this purpose are using the discrete Fourier transform (DFT) in the Frequency domain or the instantaneous p-q theory and the synchronous reference frame in the time domain. The DFT, however, suffers from the picket-fence effect and spectral leakage. On the other hand, the DFT takes at least one cycle of the Nominal Frequency. The time-domain methods show a weakness under voltage distortion, which requires prior filtering techniques. The aim of this study is to present a fast yet effective method for generating the RCC for SAPFs. The proposed method, which is based on the matrix pencil method, has a fast dynamic response and works well under distorted and unbalanced voltage. Moreover, the proposed method can estimate the voltage phase accurately; this property enables the algorithm to compensate for both power factor and current unbalance. The effectiveness of the proposed method is verified using simulation and experimental results, and compared with the standard methods.

  • an islanding detection method by using Frequency positive feedback based on fll for single phase microgrid
    IEEE Transactions on Smart Grid, 2017
    Co-Authors: Qinfei Sun, Josep M. Guerrero, Juan C. Vasquez, Tianjun Jing, Rengang Yang
    Abstract:

    An active islanding detection method based on Frequency-locked loop (FLL) for constant power controlled inverter in single-phase microgrid is proposed. This method generates a phase shift comparing the instantaneous Frequency obtained from FLL unit with the Nominal Frequency to modify the reference phase angle. An initial low Frequency variable triangular disturbance is added to the phase shift in order to reduce non-detection zone and accelerate the detection process especially in the case of power matching. With the modified phase angle, the Frequency at point of common coupling will be drifted away from the Nominal Frequency until exceeding the threshold because of the Frequency positive feedback after islanding. Besides, FLL is introduced to this method in order to lock Frequency quickly considering that the Frequency is time-varying during the islanding detection process. Simulation and experiment have been done to evaluate this method.

  • A Critical Examination of Frequency-Fixed Second-Order Generalized Integrator-Based Phase-Locked Loops
    IEEE Transactions on Power Electronics, 2017
    Co-Authors: Saeed Golestan, Seyyed Yousef Mousazadeh, Josep M. Guerrero, Juan C. Vasquez
    Abstract:

    The implementation of a large number of single-phase phase-locked loops (PLLs) involves creating a fictitious quadrature signal. A popular approach for this purpose is using a second-order generalized integrator-based quadrature signal generator (SOGI-QSG) because it results in an acceptable speed/accuracy tradeoff. The SOGI-QSG-based PLL (or briefly the SOGI-PLL), in its standard form, involves a Frequency feedback loop for adjusting the SOGI resonance Frequency under Frequency drifts. Some recent research works have reported that the speed/accuracy tradeoff of the SOGI-PLL can be considerably enhanced by removing the Frequency feedback loop. In these methods, the SOGI resonance Frequency is fixed at the Nominal Frequency, and a compensation strategy for correcting errors caused under off-Nominal frequencies is employed. The main aim of this letter is to provide a critical analysis of Frequency-fixed SOGI-based PLLs to highlight their real advantages and disadvantages.

Om P. Malik - One of the best experts on this subject based on the ideXlab platform.

  • Accurate Dynamic Phasor Estimation Based on the Signal Model Under Off-Nominal Frequency and Oscillations
    IEEE Transactions on Smart Grid, 2017
    Co-Authors: Sadegh Vejdan, Majid Sanaye-pasand, Om P. Malik
    Abstract:

    Accurate and fast estimation of power system phasors is the key to reliable operation of power system and its control/protective equipment. There have been many studies on phasor estimation techniques under dynamic and transient conditions. Although the performance under dynamic conditions of estimators based on the static phasor model has improved, significant errors still exist during large dynamic deviations. Two fast and precise dynamic phasor estimation algorithms under power system oscillations and off-Nominal Frequency conditions are described in this paper. The methods use the signal model under these dynamic conditions, linearize them by using Taylor's series expansion, and estimate the phasor using least squares technique. Frequency and its rate of change are also calculated using adjacent phasors with minimum complexity. Results obtained show that the performance errors of the proposed methods are way below the minimum requirement of the standard and better than other similar dynamic phasor algorithms.

Lingwei Zhan - One of the best experts on this subject based on the ideXlab platform.

  • a clarke transformation based dft phasor and Frequency algorithm for wide Frequency range
    IEEE Transactions on Smart Grid, 2018
    Co-Authors: Lingwei Zhan
    Abstract:

    Despite its wide applications in power grid monitoring, the classic discrete Fourier transform (DFT)-based synchrophasor estimation algorithms suffer from significant errors when the power system operates under off-Nominal Frequency conditions. This phenomenon is caused by spectral leakage of DFT and becomes even more severe for single-phase synchrophasor estimation. To address this issue, a theory to eliminate the spectral leakage-caused errors is proposed and a Clarke transformation-based DFT synchrophasor estimation algorithm is proposed to implement the theory in this paper. The Clarke transformation constructs a second signal that has exactly 90° phase angle difference from the original single-phase input signal and helps eliminate the estimation errors for a wide Frequency range. The proposed algorithm is tested under the conditions required in the phasor measurement unit standard C37.118.1-2011 and C37.118.1a-2014, as well as the harmonic and noise conditions not required in the standard to verify its performance. More importantly, the idea of using Clarke transformation can be used for other DFT-based synchrophasor algorithms in order to achieve higher synchrophasor measurement accuracy under dynamic conditions. An example is presented at last to demonstrate the expandability of the proposed idea.

Josep M. Guerrero - One of the best experts on this subject based on the ideXlab platform.

  • performance improvement of shunt active power filter based on non linear least square approach
    Electric Power Systems Research, 2018
    Co-Authors: Yacine Terriche, Josep M. Guerrero, Juan C. Vasquez
    Abstract:

    Abstract Nowadays, the shunt active power filters (SAPFs) have become a popular solution for power quality issues. A crucial issue in controlling the SAPFs which is highly correlated with their accuracy, flexibility and dynamic behavior, is generating the reference compensating current (RCC). The synchronous reference frame (SRF) approach is widely used for generating the RCC due to its simplicity and computation efficiency. However, the SRF approach needs precise information of the voltage phase which becomes a challenge under adverse grid conditions. A typical solution to answer this need is the application of advanced phase locked loops (PLLs). The PLLs are closed-loop control systems that often have a response time more than two cycles of the Nominal Frequency. Besides, a special care should be paid in designing their control parameters to ensure their stable operation in all circumstances. This paper proposes an improved open loop strategy which is unconditionally stable and flexible. The proposed method which is based on non-linear least square (NLS) approach can extract the fundamental voltage and estimates its phase within only half cycle, even in the presence of odd harmonics and dc offset. The performance of the proposed method is verified under MATLAB/Simulink environment and validated experimentally and compared with advanced PLLs.

  • matrix pencil method based reference current generation for shunt active power filters
    Iet Power Electronics, 2018
    Co-Authors: Yacine Terriche, Saeed Golestan, Josep M. Guerrero, Djallel Kerdoune, Juan C. Vasquez
    Abstract:

    In recent years, the shunt active power filters (SAPFs) have received much attention for compensating the harmonic pollution and also providing the reactive content. A crucial issue in controlling the SAPF is generating the reference compensating current (RCC). Typical approaches for this purpose are using the discrete Fourier transform (DFT) in the Frequency domain or the instantaneous p-q theory and the synchronous reference frame in the time domain. The DFT, however, suffers from the picket-fence effect and spectral leakage. On the other hand, the DFT takes at least one cycle of the Nominal Frequency. The time-domain methods show a weakness under voltage distortion, which requires prior filtering techniques. The aim of this study is to present a fast yet effective method for generating the RCC for SAPFs. The proposed method, which is based on the matrix pencil method, has a fast dynamic response and works well under distorted and unbalanced voltage. Moreover, the proposed method can estimate the voltage phase accurately; this property enables the algorithm to compensate for both power factor and current unbalance. The effectiveness of the proposed method is verified using simulation and experimental results, and compared with the standard methods.

  • an islanding detection method by using Frequency positive feedback based on fll for single phase microgrid
    IEEE Transactions on Smart Grid, 2017
    Co-Authors: Qinfei Sun, Josep M. Guerrero, Juan C. Vasquez, Tianjun Jing, Rengang Yang
    Abstract:

    An active islanding detection method based on Frequency-locked loop (FLL) for constant power controlled inverter in single-phase microgrid is proposed. This method generates a phase shift comparing the instantaneous Frequency obtained from FLL unit with the Nominal Frequency to modify the reference phase angle. An initial low Frequency variable triangular disturbance is added to the phase shift in order to reduce non-detection zone and accelerate the detection process especially in the case of power matching. With the modified phase angle, the Frequency at point of common coupling will be drifted away from the Nominal Frequency until exceeding the threshold because of the Frequency positive feedback after islanding. Besides, FLL is introduced to this method in order to lock Frequency quickly considering that the Frequency is time-varying during the islanding detection process. Simulation and experiment have been done to evaluate this method.

  • A Critical Examination of Frequency-Fixed Second-Order Generalized Integrator-Based Phase-Locked Loops
    IEEE Transactions on Power Electronics, 2017
    Co-Authors: Saeed Golestan, Seyyed Yousef Mousazadeh, Josep M. Guerrero, Juan C. Vasquez
    Abstract:

    The implementation of a large number of single-phase phase-locked loops (PLLs) involves creating a fictitious quadrature signal. A popular approach for this purpose is using a second-order generalized integrator-based quadrature signal generator (SOGI-QSG) because it results in an acceptable speed/accuracy tradeoff. The SOGI-QSG-based PLL (or briefly the SOGI-PLL), in its standard form, involves a Frequency feedback loop for adjusting the SOGI resonance Frequency under Frequency drifts. Some recent research works have reported that the speed/accuracy tradeoff of the SOGI-PLL can be considerably enhanced by removing the Frequency feedback loop. In these methods, the SOGI resonance Frequency is fixed at the Nominal Frequency, and a compensation strategy for correcting errors caused under off-Nominal frequencies is employed. The main aim of this letter is to provide a critical analysis of Frequency-fixed SOGI-based PLLs to highlight their real advantages and disadvantages.

Ranjana Sodhi - One of the best experts on this subject based on the ideXlab platform.

  • an open loop fundamental and harmonic phasor estimator for single phase voltage signals
    IEEE Transactions on Industrial Informatics, 2020
    Co-Authors: Motakatla Venkateswara Reddy, Ranjana Sodhi
    Abstract:

    This article proposes a novel technique for fundamental and selective harmonic phasor estimation of a single-phase voltage signal based on open-loop voltage signal processing approach, under adverse distorted conditions. At heart, a modified fast discrete Stockwell transform (FDST) is used for the phasor estimation. The performance of the FDST is improved by incorporating a new Frequency-dependent Gaussian window for capturing the time-localized variations of individual Frequency component. The modified window has four parameters, which are selected based on the statistical properties of the given input voltage signal. Furthermore, under off-Nominal Frequency conditions the spectral leakage problem, faced by the S-transform, is avoided by proposing a modified sample value adjustment based preprocessing stage. Various static and dynamic tests were considered according to the IEEE Standard 1159, IEEE Standard C37.118.1a-2014, and EN-50160 standards under harmonics and interharmonics scenarios. The performance of the proposed method is validated using synthetic voltage signals, simulated voltage signals on 6-bus microgrid model developed in power system computer aided design (PSCAD), and hardware implementation on dSPACE 1103. The rigorous test cases reveal that the proposed phasor measurement unit has a good adaptability to grid Frequency drifts, a good harmonic and dc-offset rejection capability, and a very good steady state as well as dynamic response.