The power quality of grid-connected inverters depends much on voltage parameters estimated by phase-locked loops. This paper proposes a robust technique for fast and accurate estimation of fundamental parameters of si...
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ISBN:
(纸本)9781467383745
The power quality of grid-connected inverters depends much on voltage parameters estimated by phase-locked loops. This paper proposes a robust technique for fast and accurate estimation of fundamental parameters of single-phase grid voltage under harmonics. The proposed technique bases on the least squares method using Levenberg-Marquardt algorithm to estimate the parameters of grid voltage. This does not base on interdependent loops offering stability and easy estimating process. It can also reject the negative effects caused by the presence of the dc offset as well as the harmonics. The simulation results in MATLAB/Simulink validated the robustness and accuracy of the proposed technique compared to the phase locked-loop basing on a second-order generalized integrator (QSG-SOGI).
The total variation regularizer is diffusely emerged in statistics, image and signal process-ing to obtain piecewise constant estimator. The t0 total variation (L0TV) regularized signal denoising model is a nonconvex ...
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The total variation regularizer is diffusely emerged in statistics, image and signal process-ing to obtain piecewise constant estimator. The t0 total variation (L0TV) regularized signal denoising model is a nonconvex and discontinuous optimization problem, and it is very difficult to find its global optimal solution. In this paper, we present the global optimality analysis of L0TV signal denoising model, and design an efficient algorithm to pursuit its solution. Firstly, we equivalently rewrite the L0TV denoising model as a partial regularized (PL0R) minimization problem by aid of the structured difference operator. Subsequently, we define a P-stationary point of PL0R, and show that it is a global optimal solution. These theoretical results allow us to find the global optimal solution of the L0TV model. Therefore, an efficient newton-type algorithm is proposed for the PL0R problem. The algo-rithm has a considerably low computational complexity in each iteration. Finally, experimental results demonstrate the excellent performance of our approach in comparison with several state-of-the-art methods.
The controllers of three-phase grid-connected inverters usually require improvements to meet the stringent grid codes 'with the fault-ride-through (FRT) capability. Therefore, the performance of the grid-connected...
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The controllers of three-phase grid-connected inverters usually require improvements to meet the stringent grid codes 'with the fault-ride-through (FRT) capability. Therefore, the performance of the grid-connected inverter depends on the quality of the selected phase-locked loop (PLL). This paper proposes a PLL method that has greater accuracy and better dynamics under an unbalanced and highly distorted voltage. The proposed method is based on the least squares technique using the Levenberg-Marquardt algorithm 'with adaptive initial parameters for rapid convergence to the solution. The simulated and experimental results under unbalanced and harmonic voltage validated the performance of the proposed method.
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