The Experts below are selected from a list of 2501040 Experts worldwide ranked by ideXlab platform

Robert G. Maliva - One of the best experts on this subject based on the ideXlab platform.

  • Vadose Zone Testing Techniques
    Anthropogenic Aquifer Recharge, 2020
    Co-Authors: Robert G. Maliva
    Abstract:

    Vadose zone hydraulic properties impact the performance of surface-spreading MAR Systems by controlling the rate of flow of water from land surface to the water table. Single- or double-ring or basin (pilot) infiltration tests are typically performed to estimate infiltration rates. Vadose zone hydraulic properties obtained from infiltration tests at land surface may differ greatly from those at depth, especially where the vadose zone is very thick. Evaluation of vadose zone properties is complicated by the zone being two phase (air and water), as opposed to the Single-Phase System of the phreatic zone. Vadose zone testing programs needs to consider the spatial variability in properties and the volume and area of investigation of tests relative to aquifer heterogeneity. Where project budgets and time are limited, the use of safety factors in design can compensate for uncertainty.

  • Vadose Zone Testing Techniques
    Anthropogenic Aquifer Recharge, 2020
    Co-Authors: Robert G. Maliva
    Abstract:

    Vadose zone hydraulic properties impact the performance of surface-spreading MAR Systems by controlling the rate of flow of water from land surface to the water table. Single- or double-ring or basin (pilot) infiltration tests are typically performed to estimate infiltration rates. Vadose zone hydraulic properties obtained from infiltration tests at land surface may differ greatly from those at depth, especially where the vadose zone is very thick. Evaluation of vadose zone properties is complicated by the zone being two phase (air and water), as opposed to the Single-Phase System of the phreatic zone. Vadose zone testing programs needs to consider the spatial variability in properties and the volume and area of investigation of tests relative to aquifer heterogeneity. Where project budgets and time are limited, the use of safety factors in design can compensate for uncertainty.

Amer M. Y. M. Ghias - One of the best experts on this subject based on the ideXlab platform.

  • Open-Loop Approach for Robust Detection of Selective Harmonic in Single-Phase System
    IEEE Transactions on Industrial Informatics, 2019
    Co-Authors: Shamim Reza, Maruf Hossain, Amer M. Y. M. Ghias
    Abstract:

    This paper proposes an open-loop approach for selective harmonic detection from the Single-Phase power System under changeable frequency environment. It consists of a frequency tracking algorithm relying on a fixed tuned demodulation method and a selective harmonic detection scheme based on an adaptively tuned cascaded delayed signal cancellation (CDSC) strategy. It can be easily arranged to detect one or several harmonic(s) from the input signal contaminated by different harmonics. The open-loop configuration makes the proposed technique robust, free of interdependent loop, easy tuning, and unconditionally stable. The real-time utilization of trigonometric and inverse trigonometric functions is also avoided in the technique. When compared with the discrete Fourier transform and CDSC-based technique reported in the technical literature, it demands less computational effort and can create faster dynamics and better steady-state accuracy in the estimated frequency. The usefulness of the technique is confirmed by simulation and real-time experimental results.

Shamim Reza - One of the best experts on this subject based on the ideXlab platform.

  • Robust estimation of voltage harmonics in a Single-Phase System
    IET Science Measurement & Technology, 2019
    Co-Authors: Shamim Reza, Mihai Ciobotaru, Maruf Hossain, Vassilios G. Agelidis
    Abstract:

    A frequency adaptive technique relying on a linear Kalman filter (KF) is presented here for robust estimation of voltage harmonics under variable frequency conditions in a Single-Phase System. A relatively simple frequency-locked loop (FLL) is combined with the linear KF (LKF-FLL) to achieve frequency adaptive ability and avoid the use of a non-linear KF. In contrast to the non-linear extended KF (EKF), the LKF-FLL technique has several advantages such as robustness, linearity, simple tuning, having fewer states, requiring no derivative actions, while offering low complexity, excellent convergence, and computational efficiency. When compared to the non-linear extended real KF, it can generate a faster dynamic response and more accurate steady-state estimation of the harmonics under frequency variations. It can also provide an improved estimation for off-nominal frequency conditions when compared to the discrete Fourier transform (DFT) method. The effectiveness of the technique is verified by various simulated and real-time experimental case studies.

  • Open-Loop Approach for Robust Detection of Selective Harmonic in Single-Phase System
    IEEE Transactions on Industrial Informatics, 2019
    Co-Authors: Shamim Reza, Maruf Hossain, Amer M. Y. M. Ghias
    Abstract:

    This paper proposes an open-loop approach for selective harmonic detection from the Single-Phase power System under changeable frequency environment. It consists of a frequency tracking algorithm relying on a fixed tuned demodulation method and a selective harmonic detection scheme based on an adaptively tuned cascaded delayed signal cancellation (CDSC) strategy. It can be easily arranged to detect one or several harmonic(s) from the input signal contaminated by different harmonics. The open-loop configuration makes the proposed technique robust, free of interdependent loop, easy tuning, and unconditionally stable. The real-time utilization of trigonometric and inverse trigonometric functions is also avoided in the technique. When compared with the discrete Fourier transform and CDSC-based technique reported in the technical literature, it demands less computational effort and can create faster dynamics and better steady-state accuracy in the estimated frequency. The usefulness of the technique is confirmed by simulation and real-time experimental results.

Subhashish Bhattacharya - One of the best experts on this subject based on the ideXlab platform.

  • Terminal voltage analysis for the transformerless PV inverter topologies in a single‐phase System
    IET Renewable Power Generation, 2019
    Co-Authors: Venu Sonti, Sachin Jain, Vivek Agarwal, Subhashish Bhattacharya
    Abstract:

    This study presents an analysis of the terminal voltage of the basic photovoltaic (PV) inverter topologies available in the literature. The presented analysis utilises the switching function concept. Use of switching function in the analysis enables the inclusion of the effect of the pulse-width modulation technique or the switching strategy on the terminal voltage of the reviewed configuration. It gives insight into the switching action effects on the terminal voltage and provides every detail of the high-frequency transitions in the terminal voltage for the given switching strategy. Using the terminal voltage expression derived in terms of switching function, the analytical waveforms are obtained for various configurations. These waveforms are compared with the simulation and experimental results waveforms to justify the analysis given. This study also presents a bar chart view of the switching and conduction losses of the switches in the reviewed PV inverter topologies. The magnitude of high-frequency components in the terminal voltage and the leakage current is also presented in this study. The PV inverter topologies are also compared in terms of other aspects such as a number of devices used, asymmetry in operation, filter requirement etc.

Han Zhang - One of the best experts on this subject based on the ideXlab platform.

  • low frequency stability analysis of single phase System with dq frame impedance approach part i impedance modeling and verification
    IEEE Transactions on Industry Applications, 2018
    Co-Authors: Yicheng Liao, Zhigang Liu, Han Zhang, Bo Wen
    Abstract:

    The utilization of a large number of power electronic converters in the high-speed railway System results in the low-frequency instability for the Single-Phase vehicle-grid System. In order to probe into the problem, the impedance-based approach is adopted. This paper focuses on the dq -frame impedance modeling and verification of the Single-Phase converters in the electric multiple units. The closed-loop input impedance modeling methods for both single converter and interleaved converters considering the second-order generalized integrator-based phase-locked loop (PLL) are put forward. Then, the dq -frame impedance measurement method for Single-Phase Systems based on the Hilbert transform is proposed, and the modeling approach is verified by the frequency-domain simulations on the switching models. The good agreement of the model and simulation illustrates that the modeling method is suitable and accurate enough until half of the switching frequency. It is elucidated that the Single-Phase rectifier's impedance has the off-diagonal characteristic and the negative-impedance characteristic on the dd channel at low frequencies. Moreover, both the current and voltage controls have influences on the negative impedance shaping, while PLL does not.

  • Low-Frequency Stability Analysis of Single-Phase System With dq-Frame Impedance Approach—Part I: Impedance Modeling and Verification
    IEEE Transactions on Industry Applications, 2018
    Co-Authors: Yicheng Liao, Han Zhang
    Abstract:

    The utilization of a large number of power electronic converters in the high-speed railway System results in the low-frequency instability for the Single-Phase vehicle-grid System. In order to probe into the problem, the impedance-based approach is adopted. This paper focuses on the dq-frame impedance modeling and verification of the Single-Phase converters in the electric multiple units. The closed-loop input impedance modeling methods for both single converter and interleaved converters considering the second-order generalized integrator-based phase-locked loop (PLL) are put forward. Then, the dq-frame impedance measurement method for Single-Phase Systems based on the Hilbert transform is proposed, and the modeling approach is verified by the frequency-domain simulations on the switching models. The good agreement of the model and simulation illustrates that the modeling method is suitable and accurate enough until half of the switching frequency. It is elucidated that the Single-Phase rectifier's impedance has the off-diagonal characteristic and the negative-impedance characteristic on the dd channel at low frequencies. Moreover, both the current and voltage controls have influences on the negative impedance shaping, while PLL does not.