scholarly journals Enhanced controller for a four-leg inverter operating in a stand-alone microgrid with unbalanced loads

2021 ◽  
Vol 12 (4) ◽  
pp. 2372
Author(s):  
Effat Ayoubi ◽  
Mohammad Reza Miveh ◽  
Ali Asghar Ghadimi ◽  
Sajad Bagheri
Keyword(s):  
Distribution Systems ◽  
Low Voltage ◽  
Neutral Current ◽  
Superior Performance ◽  
Control Technique ◽  
Unequal Distribution ◽  
Current Path ◽  
Three Phase ◽  
Unbalanced Load ◽  
Utility Grid

<span lang="EN-US">Stand-alone low voltage (LV) microgrids supplying small local loads far from the utility grid are becoming an increasingly popular alternative to a total reliance on the centralized utility grid. In most of LV microgrids, three-phase four-wire distribution systems are used to supply both single- and three-phase loads. Unequal distribution of loads can result in voltage unbalance problems. The use of the four-leg inverter is one of the best solutions for providing a neutral current path and compensating unbalanced load conditions in stand-alone LV microgrids. This paper proposes a fast control technique to compensate unbalanced voltage conditions for a four-leg inverter operating in a stand-alone LV microgrid. The suggested technique provides the current controller’s orthogonal component without introducing any additional dynamics or distortions. The major benefits of the recommended per-phase control technique over conventional orthogonal signal generation (OSG) methods are enhanced steady-state and dynamic performances as well as independency to the system parameters. Several simulation results are provided to confirm the superior performance of the suggested methods.</span>

scholarly journals Synchronized Control of Voltage and Current Harmonics in Distributed Generation System using Fuzzy Controller

2019 ◽  
Vol 8 (12) ◽  
pp. 1179-1182
Keyword(s):  
Distributed Generation ◽  
Energy Demand ◽  
Power Flow ◽  
Fuzzy Controller ◽  
Low Voltage ◽  
Load Condition ◽  
Control Technique ◽  
Current Harmonics ◽  
Simultaneous Control ◽  
Unbalanced Load

The worldwide energy demand is increasing due to increase in population and economic growth. The grid is gradually replaced by Distributed generation systems (DGs). Recently low voltage DG interfacing converter on the non linear load compensation is performed by unified power flow converter. The proposed control technique is analyzed for Simultaneous control of voltage and power under unbalanced load condition using MATLAB/SIMULINK software

scholarly journals Asymmetric Compensation of Reactive Power Using Thyristor-Controlled Reactors

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 880
Author(s):  
Martynas Šapurov ◽  
Vytautas Bleizgys ◽  
Algirdas Baskys ◽  
Aldas Dervinis ◽  
Edvardas Bielskis ◽  
...  
Keyword(s):  
Experimental Test ◽  
Single Phase ◽  
Test Bench ◽  
Reactive Power ◽  
Low Voltage ◽  
And Topology ◽  
Three Phase ◽  
Thyristor Controlled Reactor ◽  
Utility Grid ◽  
Experimental Test Bench

The thyristor-controlled reactor (TCR) compensator for smooth asymmetric compensation of reactive power in a low-voltage utility grid is proposed in this work. Two different topologies of compensator were investigated: topology based on a single-cored three-phase reactor and topology with separate reactors for every phase. The investigation of the proposed TCR compensator was performed experimentally using a developed experimental test bench for 12 kVAr total reactive power. The obtained results show that employment of separate reactors for every phase allows us to control the reactive power in every phase independently, and that the TCR compensator with three single-phase reactors is suitable for smooth and asymmetric compensation of reactive power in a low-voltage utility grid.

scholarly journals Configuration of smart phase-swapping switches in low-voltage distribution systems based on sequenced participation indices

2020 ◽  
Vol 53 (7-8) ◽  
pp. 1159-1170
Author(s):  
Lixia Cao ◽  
Guoliang Feng ◽  
Xingong Cheng ◽  
Luhao Wang
Keyword(s):  
Distribution Systems ◽  
Single Phase ◽  
Low Voltage ◽  
Economic Benefits ◽  
Voltage Distribution ◽  
Practical Applications ◽  
Three Phase ◽  
Participation Index ◽  
Configuration Problem ◽  
High Phase

The smart phase-swapping switches are used to rapidly change the phases of single-phase loads online in low-voltage distribution systems. They can reduce the three-phase imbalance indices. However, the effectiveness of phase-swapping operations is determined by not only the control strategy but also by the quantity and locations of smart phase-swapping switches. In this paper, a configuration method is proposed to determine the preferable quantity and locations of smart phase-swapping switches with considerations of economic benefits and operational requirements. Based on historical load information, the active and reactive powers of the loads are used to formulate the current imbalance index. The configuration problem is modeled as a multiobjective optimization that minimizes the current imbalance indices of all nodes and phase-swapping operations. The problem is solved by the particle swarm optimization algorithm to obtain the phase-swapping participation index of each single-phase load. The loads with high phase-swapping participation indices are preferably equipped with smart phase-swapping switches. The simulation results verify that the proposed method is effective and easy to be implemented in practical applications.

scholarly journals An Alternate Representation of the Vector of Apparent Power and Unbalanced Power in Three-Phase Electrical Systems

2020 ◽  
Vol 10 (11) ◽  
pp. 3756
Author(s):  
Pedro A. Blasco ◽  
Rafael Montoya-Mira ◽  
José M. Diez ◽  
Rafael Montoya
Keyword(s):  
Nonlinear Systems ◽  
Distribution Systems ◽  
Low Voltage ◽  
Practical Case ◽  
Voltage Distribution ◽  
Efficient System ◽  
Electrical Systems ◽  
Three Phase ◽  
Unbalanced Loads ◽  
Wire System

Low-voltage distribution systems are typically unbalanced. These inefficiencies cause unbalanced powers that can significantly increase the apparent power of the system. Analysing and measuring these inefficient powers appropriately allows us to compensate for them and obtain a more efficient system. Correcting the imbalance at some nodes can worsen the rest of the system; therefore, it is essential that all nodes are analysed such that action can be taken when necessary. In most studies, the unbalanced power is measured from the modulus. Other more recent studies have proposed phasor expressions of unbalanced powers; however, in both cases, these are not enough to address the compensation of unbalanced powers in systems with unbalanced voltages. In this work, a different representation of the vector expressions for analysis of the unbalanced powers and the apparent powers of the three-phase linear systems is proposed. Additionally, these vector expressions are extended to nonlinear systems to quantify the harmonic apparent powers. These expressions have been formulated from the power of Buchholz and are valid for systems with unbalanced voltages and currents. To help understand the use of the proposed formulation, a practical case of a three-phase four-wire system with unbalanced loads and voltages is demonstrated.

scholarly journals Energy Efficiency Study for the Distribution System Using Low Voltage Transformer Under Harmonic Conditions

2021 ◽  
Author(s):  
Bruno M. Laurindo ◽  
Felipe Marins ◽  
Bruno Wanderley França ◽  
Marcio Zamboti Fortes ◽  
Mauricio Aredes
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Power Flow ◽  
Distribution Systems ◽  
Low Voltage ◽  
Energy Losses ◽  
Nonlinear Loads ◽  
Voltage Transformer ◽  
Operation Temperature ◽  
Three Phase

In Brazil, technical energy losses in power distribution systems are determined by power flow studies considering medium and low voltage systems, according to ANEEL recommendations, presented in PRODIST Module 7. These technical losses occur due to physical phenomena and are intrinsically associated with the energy distribution process. However, standards currently do not consider energy losses from harmonic components generated by nonlinear loads, which represent almost all the loads present in electrical systems worldwide. Thus, this paper aims to analyze the operation of a low voltage transformer under harmonic current conditions and to evaluate not only the operation temperature of the equipment, but also to verify the energy losses in it. This test is performed on a laboratory platform and the results are experimental using an adjustable three-phase source and a 3kVA three-phase transformer.

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