An enhanced output voltage compensator for inverter under nonlinear load and voltage distortions

Parallel-connected uninterruptible power supply (UPS) systems have been used to maintain power supply to the critical load in order to increase power capacity and system reliability. This paper presents a robust and precise voltage control strategy for parallel-connected UPS systems. Each parallel-connected UPS system consists of a three-phase inverter with an output inductor-capacitor (LC) filter directly connected to an AC common bus in order to feed the critical load. Fractional-order sliding mode control (FOSMC) is proposed to maintain the quality of the output voltage despite linear, unbalanced and/or nonlinear load condition. The Riemann-Liouville (RL) fractional derivative is employed in designing the sliding surface. The voltage control strategy effectively eliminates the parametric uncertainties, external disturbances, and reduce the total harmonic distortion (THD) of the output voltage. Furthermore, it also maintains very good voltage regulation such as dynamic response and steady-state error under the nonlinear or unbalanced load conditions. The stability of the proposed controller is proven by applying Lyapunov stability theory. Droop control approach and virtual output impedance (VOI) loop are investigated to guarantee the accurate active and reactive power-sharing for parallel-connected UPS system. Finally, the implementation of the control scheme is carried out by using MATLAB/Simulink real-time environment.

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Multiple AI based Controlling Techniques for Power Filter Output Quality Improvement

SMART MOVES JOURNAL IJOSCIENCE ◽

10.24113/ijoscience.v7i1.342 ◽

2021 ◽

Vol 7 (1) ◽

pp. 11-20

Author(s):

Rajesh Raghuvanshi ◽

Dr Sukul Lomash

Keyword(s):

Distribution System ◽

Output Voltage ◽

Learning Algorithm ◽

Harmonic Distortion ◽

Active Filter ◽

Voltage Source ◽

Quality Factors ◽

Nonlinear Load ◽

Shunt Active Filter ◽

Power Filter

The excessive of power electronics devices in distribution system has evolved the problem of power quality. This work represents the effective solution of shunt active power filter for eliminating the harmonics to maintain the quality of utility power supply. In the proposed scheme shunt active filter acts as a voltage source and eliminates harmonics by injecting equal but opposite harmonics components at the point of common coupling. Simulation of shunt active filter based on instantaneous reactive has been achieved in the MATLAB/SIMULINK environment. The controllers are being designed with the objective of reducing the THD% in voltage and current available at the nonlinear load terminal of the system. The controller incorporated optimization algorithms based on the artificial intelligence techniques as well. The comparative analysis of the effectiveness and efficiency of the controllers in improving the quality factors has been carried out. The distortion level in the output voltage waveforms in both the cases being fed to the load when compared, it is found that proposed hybrid structure of control for the filter is more effective in reducing the distortion as compared to standard PQ theory based architecture. The study concluded that the total harmonic distortion in the voltage output waveform being fed to the load using only PQ theory based online learning algorithm is found to be 1.59 % while in case of the output voltage at the load terminal from the power filter using proposed hybrid algorithm comprising of NN learning with CSA optimizing control and PQ_RLS algorithm for THD reduction the THD% level is 0.43 %.

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Non-linear Characteristic of Output Voltage and Method for Determining Carrier Frequency in a Series Voltage Compensator

IEEJ Transactions on Industry Applications ◽

10.1541/ieejias.133.676 ◽

2013 ◽

Vol 133 (7) ◽

pp. 676-684

Author(s):

Atsushi Nakata ◽

Masahiro Nozaki ◽

Akihiro Torii ◽

Akiteru Ueda

Keyword(s):

Carrier Frequency ◽

Output Voltage ◽

Voltage Compensator ◽

Linear Characteristic ◽

Non Linear

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Design of Efficient Power Filter with Reduced Distortion Using Control Algorithm

IJOSTHE ◽

10.24113/ijosthe.v7i4.129 ◽

2020 ◽

pp. 1-10

Author(s):

Rahul Dhakad ◽

Dr. Rakesh Saxena

Keyword(s):

Distribution System ◽

Output Voltage ◽

Harmonic Distortion ◽

Total Harmonic Distortion ◽

Renewable Energy Resources ◽

Nonlinear Loads ◽

Nonlinear Load ◽

Power Filter ◽

Distortion Level ◽

Voltage Output

The electrical distribution system is facing undesirable power quality disturbances due to different types of linear/nonlinear loads on the supply system. The objective of the project is to reduce the distortion level in voltage or current input to the load and at the output of the filter. To design a simple but highly viable hybrid active power buffer that is capable of feeding less distorted voltage to the nonlinear load model. To present an optimal controlling of these buffers so as to minimize the voltage distortion by designing a different algorithm for the same. Comparing the THD levels of the output voltage waveform with the standard controlling method with the proposed control design to further enhance the proposed design such that it is practically feasible to be implemented in grid system having renewable energy resources. In this work, a power filter has been designed using different algorithms with an objective to reduce the Total Harmonic Distortion in the voltage output waveforms. The total harmonic distortion in the voltage output waveform being fed to the load using only the PQ_RLS algorithm is found to be 2.18 %. In the case of the output voltage from the power buffer using PQ_RLS algorithm, the THD level is 0.17 %. The distortion level in the output voltage waveforms in both the cases being fed to the load when compared, it is found that RLS algorithm in combination with PQ algorithm is more effective in reducing the distortion as compared to standard RLS method or PQ method.

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Three phase voltage source inverters with grid connected industrial application

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i2.9.9653 ◽

2018 ◽

Vol 7 (4) ◽

pp. 18 ◽

Cited By ~ 1

Author(s):

Prakash N ◽

Balaji V.R.

Keyword(s):

Output Voltage ◽

Control Algorithm ◽

Power Flow ◽

Pulse Width Modulation ◽

Control Technique ◽

Voltage Source ◽

Phase Voltage ◽

Nonlinear Load ◽

Three Phase ◽

Park Transformation

The grid-connected issue is one of the major problems in the field of Power Electronics. In this paper, the Three Phase Voltage Source Inverter (VSI) is controlled by a Space Vector Pulse Width Modulation (SVPWM) Technique. SVPWM control technique and Park transformation, the managed inverter control system to convert input DC power into AC power, stabilize the output voltage and current, and feeds the excess power to the utility grid can be achieved by controllers. Usually, the grid source contains higher level of harmonics. To analyze the harmonics, nonlinear load is connected externally in the point of common coupling. The main aim of this paper is to modeling, simulation and experimental study of the three-phase grid connected inverter. By using the control algorithm, the grid sides Total Harmonics Distortion (THD) are controlled to the 1.54% for 800V DC as per the IEEE standard. The stimulation results such as AC output voltage and current, inverter system power flow, and grid disturbances detection signals, proves the effectiveness of the developed control algorithm. The control algorithms to makes the for this inverter outputs is pure sinusoidal.

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Passivity-Based Control Design Methodology for UPS Systems

Energies ◽

10.3390/en12224301 ◽

2019 ◽

Vol 12 (22) ◽

pp. 4301 ◽

Cited By ~ 5

Author(s):

Rymarski ◽

Bernacki ◽

Dyga ◽

Davari

Keyword(s):

Output Voltage ◽

Design Methodology ◽

Control Design ◽

Power Converter ◽

Voltage Source ◽

Phase Voltage ◽

Nonlinear Load ◽

Voltage Source Inverters ◽

Three Phase ◽

Passivity Based Control

This paper presents a passivity-based control (PBC) design methodology for three-phase voltage source inverters (VSI) for uninterruptable power supply (UPS) systems where reduced harmonic distortions for the nonlinear load, reduced output voltage overshoot, and a restricted settling time are required. The output filter design and modification for efficient control and existing challenges with the assignment of scaling coefficients of the output voltage, load, and inductor currents are addressed and analyzed. Notably, special attention is given to the modulator saturation issue through implementing an accurate converter model. Applications of the two versions of PBC in three-phase voltage source inverters using stationary αβ and rotating dq frames for a constant frequency of the output voltage are presented. Furthermore, the influence of the PBC parameters on the power converter performance is investigated. A comparative simulation and the experimental results validate the effectiveness of the presented passivity-based control design methodology.

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Stability analysis of microgrid inverter off-grid mode considering nonlinear load

Journal of Physics Conference Series ◽

10.1088/1742-6596/2108/1/012090 ◽

2021 ◽

Vol 2108 (1) ◽

pp. 012090

Author(s):

Xiaoyan Shi ◽

Bin Wang ◽

Shuijuan Yu

Keyword(s):

Output Voltage ◽

Large Scale ◽

Load Capacity ◽

Impedance Analysis ◽

Load Level ◽

System Stability ◽

Impedance Change ◽

Actual System ◽

Nonlinear Load ◽

Loop Control

Abstract With the large-scale utilization of distributed generation in microgrid, inverter as the connection hub of new energy grid connection, directly affects the operation performance of microgrid. In order to improve the output voltage quality and load capacity of the inverter in the off-grid mode of distributed energy, the stability region of the inverter with load is analyzed by using the impedance analysis method of cascade converter and control theory. The quasi proportional resonant (QPR) double loop control is adopted to realize no static error tracking voltage while increasing bandwidth, and the influence of control parameters on performance is analyzed. At the same time, in order to improve the capacity of inverter with nonlinear load, odd harmonics are introduced into the controller to suppress the influence of low harmonics of load current on output voltage. Finally, the influence of inverter output impedance change, load level, controller parameters and filter parameters on system stability is analyzed through impedance ratio Nyquist curve, which provides corresponding theoretical support and parameter optimization reference for the design of actual system.

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