scholarly journals Active Power Transfer Enhancement in VSC using Impedance Compensated DSRF-PLL during Weak Grid Condition

2019 ◽  
Vol 8 (4) ◽  
pp. 2693-2966
Keyword(s):  
Active Power ◽  
Stable Operation ◽  
Phase Detection ◽  
Power Transfer ◽  
Renewable Sources ◽  
Weak Grid ◽  
Synchronous Reference Frame ◽  
Grid Impedance ◽  
Point Of Common Coupling ◽  
Common Coupling

In last two decades the use of renewable sources has been increased tremendously. This has increased the number of inverters connected to grid for the integration of energy from renewable sources. The stability of grid tied inverter is very much important with increased number of inverters. Especially in weak grid, which leads to voltage fluctuation, stability of inverter needs more attention. For a stable operation of VSC it is very important to detect the phase of grid voltage at point of common coupling (PCC) with proper accuracy. In this paper a Double Synchronous Reference Frame PLL (DSRF-PLL) with grid impedance compensation is presented. It is shown that with grid impedance compensation in phase detection, a VSC can be virtually synchronized at a stronger point of common coupling (PCC) in grid and this will enhance the active power transfer capacity of VSC with stable operation in weak grid condition. MATLAB simulation results are presented to verify the findings.

scholarly journals A Comparison Between Robust Control Design LMIs for Grid-Connected Converters

2021 ◽  
Author(s):  
GUSTAVO GUILHERME KOCH ◽  
CAIO RUVIARO DANTAS OSóRIO ◽  
VINICIUS FOLETTO MONTAGNER
Keyword(s):  
Superior Performance ◽  
Linear Matrix ◽  
Feedback Controllers ◽  
Quadratic Stability ◽  
Slack Variables ◽  
Grid Impedance ◽  
Point Of Common Coupling ◽  
Common Coupling ◽  
Robust Control Design ◽  
Grid Connected Converters

This paper is focused on a comparison between two linear matrix inequality conditions for design of robust state feedback controllers applied for current regulation of gridconnected converters with LCL filters, operating under uncertain grid impedance at the point of common coupling. The first condition is the well known quadratic stability and the second one is the polyquadratic stability, which uses extra matrix variables. It is shown that the condition with slack variables can provide superior performance in terms of ensuring stable and suitable operation for a larger set of uncertainties.

A New Compensation Control Strategy for Grid-connected Wind Turbine and Fuel Cell Inverters in a Microgrid

2017 ◽  
Vol 8 (1) ◽  
pp. 272 ◽  
Author(s):  
A. Naderipour ◽  
A. A. Mohd Zin ◽  
M. H. Habibuddin ◽  
M. Moradi ◽  
M. Miveh ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Wind Turbine ◽  
Distributed Generation ◽  
Control Method ◽  
Harmonic Distortion ◽  
Synchronous Reference Frame ◽  
Wide Range ◽  
Point Of Common Coupling ◽  
Frame Method ◽  
Common Coupling

The use of a new control method for grid-connected inverters for reducing the output current harmonic distortion in a wide range of grid-connected distributed generation (DG) applications, including wind turbine (WT) and fuel cell (FC) inverters is proposed in this paper. The control method designed to eliminate main harmonics in a microgrid (MG) and between MG and point of common coupling (PCC) and responsible for the correction of the system unbalance. Another advantage of the proposed control method is that it can be easily adopted into the DG control system without the installation of extra hardware. The proposed control method is comprised of the synchronous reference frame method (SRF). Results from the proposed control method are provided to show the feasibility of the proposed approach.

scholarly journals Measurement-Based Distribution Grid Harmonic Impedance Models and Their Uncertainties

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4259
Author(s):  
Ravi Shankar Singh ◽  
Vladimir Ćuk ◽  
Sjef Cobben
Keyword(s):  
Estimation Method ◽  
Distribution Grid ◽  
Harmonic Model ◽  
Equivalent Models ◽  
Grid Impedance ◽  
Before And After ◽  
Point Of Common Coupling ◽  
Simulated Network ◽  
Common Coupling ◽  
Impedance Models

Aggregated Norton’s equivalent models, with parallel impedance and current injection at different harmonic frequencies are used to model the distribution grid in harmonic studies. These models are derived based on measurements and/or prior knowledge about the grid. The measurement-based distribution (sub-)grid impedance estimation method uses harmonic phasors of 3-phase current and voltage measurements to capture the response of the distribution (sub-)grid before and after an event in the utility side of the grid. However, due to increasing non-linear components in the grid, knowledge about uncertainty in parameters of such equivalent models which intrinsically describe a linear grid becomes important. The aim of this paper is to present two novel methods to calculate the uncertainty of the measurement-based Norton’s equivalent harmonic model of the distribution (sub-)grids as seen from the utility side at the Point of Common Coupling (PCC). The impedance and the uncertainty calculations are demonstrated on a simulated network.

scholarly journals Adaptive Impedance-Conditioned Phase-Locked Loop for the VSC Converter Connected to Weak Grid

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6040
Author(s):  
Mostafa A. Hamood ◽  
Ognjen Marjanovic ◽  
Joaquin Carrasco
Keyword(s):  
Reference Frame ◽  
Upper Bound ◽  
Closed Loop ◽  
Dynamic Performance ◽  
Phase Locked Loop ◽  
Estimation Methods ◽  
Weak Grid ◽  
Synchronous Reference Frame ◽  
Grid Impedance ◽  
Virtual Impedance

In this paper, an adaptive version of the impedance-conditioned phase-locked loop (IC-PLL), namely the adaptive IC-PLL (AIC-PLL), is proposed. The IC-PLL has recently been proposed to address the issue of synchronisation with a weak AC grid by supplementing the conventional synchronous reference frame phase-locked loop (SRF-PLL) with an additional virtual impedance term. The resulting IC-PLL aims to synchronise the converter to a remote and stronger point in the grid, hence increasing the upper bound on the achievable power transfer achieved by the VSC converter connected to the weak grid. However, the issue of the variable grid strength imposes another challenge in the operation of the IC-PLL. This is because the IC-PLL requires impedance estimation methods to estimate the value of the virtual impedance part. In AIC-PLL, the virtual impedance part is estimated by appending another dynamic loop in the exciting IC-PLL. In this method, an additional closed loop is involved so that the values of the virtual inductance and resistance are internally estimated and adapted. Hence, the VSC converter becomes effectively viable for the case of the grid strength variable, where the estimation of the grid impedance becomes unnecessary. The results show that the converter that relies on AIC-PLL has the ability to transfer power that is approximately equal to the theoretical maximum power while maintaining satisfactory dynamic performance.

Modified Synchronous Reference Frame Based Harmonic Extraction for Shunt Active Filter

2015 ◽  
Vol 6 (4) ◽  
pp. 897
Author(s):  
C.S. Subash Kumar ◽  
V. Gopalakrishnan
Keyword(s):  
Reference Frame ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Active Filter ◽  
Shunt Active Filter ◽  
Synchronous Reference Frame ◽  
Point Of Common Coupling ◽  
Harmonic Extraction ◽  
Common Coupling ◽  
Non Linear Load

<p>This paper presents the modified synchronous reference frame based Shunt Active Filter (SAF) for the instantaneous compensation of harmonic current present at the Point of Common Coupling. The harmonics generated by the non linear load are extracted using the positive frame and negative frame of the input signal using the modified synchronous reference frame theory with extended Multiple Reference Frame based PLL (EMRFPLL). Based on the harmonics extracted, pulse width modulation signals are generated using Artificial Neural Network based Space Vector Pulse width Modulation technique (ANNSVPWM). Using this switching technique the losses can be reduced and compensation can be done more accurately The concept was verified using MATLAB / Simulink Simulation and the results confirm the THD at point of common coupling is below the required standards.</p>

Method of Parallel Active Power Filter Compensation on 3-Phase 3-Wire Nonlinear Unbalanced Load System

2011 ◽  
Vol 128-129 ◽  
pp. 185-189
Author(s):  
Wen Xue Zou ◽  
Sheng Hui Liu
Keyword(s):  
Power Flow ◽  
Flow Direction ◽  
Active Power Filter ◽  
Active Power ◽  
Positive Direction ◽  
Power Filter ◽  
Point Of Common Coupling ◽  
Unbalanced Load ◽  
Active Power Flow ◽  
Common Coupling

The parallel active power filter has been accepted by users because of its’ installing and removing without disturbing other users and so its’ detecting and controlling algorithms have been studied with large efforts .A method about direction of active power flow (DAPF ) was raised in present paper under condition of the 3-phase asymmetrical voltage and 3-wire nonlinear unbalanced load. It’s means that detected currents on the point of common coupling can be put into two parts according the active power flow direction ,one of which is called positive direction current and another is called negative direction current .then decompose the asymmetrical voltage and positive directional current with Symmetrical Component Method. We can obtain the reference current components with clear physical meaning for the paralleled active power filter .The method shows there are several harmful power components could not be eliminated with parallel active power filter.

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