Multi-converter Unified Power Quality Conditioner Research Articles

Multi-Converter UPQC Optimization for Power Quality Improvement Using Beetle Swarm-Based Butterfly Optimization Algorithm

The primary goal of this paper is to design a Multi-Converter Unified Power Quality Conditioner (MC-UPQC). The proposed method is solved based on the Synchronous Reference Frame (SRF) theory. The MC-UPQC involves two series Voltage Source Converters (VSCs) for power transfer between feeders to eliminate voltage sag, swell, interruption, and transient response in the system. The proposed model adopts control strategies based on an optimized Fuzzy Logic Controller (FLC) in SRF, utilizing a hybrid metaheuristic algorithm called Beetle Swarm-based Butterfly Optimization Algorithm (BS-BOA), which combines Beetle Swarm Optimization (BSO) and Butterfly Optimization Algorithm (BOA) for membership limit optimization and control rule generation. The major benefit of the optimized FLC-based MC-UPQC is its quick behavior in minimizing Total Harmonic Distortion (THD) in source and load side voltages and currents. Simulation and MATLAB environment are used for the entire system implementation. The comparative analysis of the proposed controller for MC-UPQC is performed against conventional controllers to validate its effectiveness. Quantitative data related to the main research outcomes, such as THD of source voltage and current, and dynamic behavior of the system, are included. The main benefit of the study is the significant reduction in THD and improved dynamic performance of the system.

Fault mitigation through multi converter UPQC with hysteresis controller in grid connected wind system

The ability of parallel compensation for voltage and current in bus system is known as Multi Converter Unified Power Quality Conditioner (MC-UPQC). It improve the Power Quality (PQ) of the renewable energy sources. The combination of current and voltage quality is known as PQ. The PQ problems, named as imbalance, flicker, and harmonics, the electronically switched and nonlinear devices with increasing applications in distribution systems and industries have become serious concerns. In this paper, improved fuzzy-based MC-UPQC is proposed for improving the PQ in grid connected wind energy system (WES). Improved fuzzy, that is hybrid fuzzy incremental conductance controlled MC-UPQC is the novelty in this study. Fuzzy incremental conductance is introduced to search the maximum power point in wind energy conversion system. From the grid, the proposed controller joined with MC-UPQC improve the WES. At the same time, the system can recompense the current and voltage imperfections in adjacent feeders. A normal dc-link capacitor is shared by all converters in this configuration. Hence, the power transfer from one to adjacent feeders is possible. The proposed work is simulated in MATLAB/SIMULINK platform. Through the hysteresis controller, the performance analysis is carried out. Finally the results are compared with existing controller’s namely proportional integral and a conventional fuzzy logic controller. Thus, the overall performance can display the effectiveness of the proposed approach. Compared to other two existing approaches, the proposed scheme achieves very low THD values i.e. 3.53% for load 1 and 3.25% for load 2.

Performance analysis of multiconverter unified power quality conditioner with an EPLL-based controller at medium voltage level

Summary In this paper, one of the known interline custom power devices named Multiconverter Unified Power Quality Conditioner (MCUPQC) is designed for medium voltage level (11 kV) and improved for various power quality disturbances. An effective enhanced phase-locked loop-based control technique is applied to detect and extract the power quality disturbances for each phase separately. The performance of series compensators of MCUPQC is evaluated through extensive simulations for mitigating unbalanced voltage sags with phase jumps, swell, and interruption. Presag compensation method, which includes a novel phase-freezing algorithm, is preferred for sensitive load to mitigate the impact of phase angle jumps. The performance of shunt compensator of MCUPQC is tested for harmonic compensation, reactive power compensation, and direct current link voltage regulation. It is verified that MCUPQC, which is connected to two feeders, can compensate current and voltage imperfections successfully in these feeders according to the results obtained using PSCAD/EMTDC.

Power Angle Control-based Method for Interline Unified Power Quality Conditioner and Multi-converter Unified Power Quality Conditioner under Unbalanced and Distorted Load Conditions

This article proposes a new control approach for an interline unified power quality conditioner and a multi-converter unified power quality conditioner to optimize the utilization of the inverters of these structures. In this method, the series active power filter is controlled by the application of a power angle control concept to compensate an unbalanced voltage (asymmetrical voltage sag/swell with or without phase angle jumps) and also partial-load reactive power for power factor correction. Since voltage variation (sag/swell, unbalance, etc.) is a short-duration power quality problem in distribution systems, under normal operating conditions, series inverters are not utilized effectively in conventional methods. By using the proposed method, optimal utilization of series inverters of both structures and also a reduction in the shunt inverter rating of a multi-converter unified power quality conditioner will be achieved. Also, the shunt active power filter is controlled to compensate the unbalanced current, harmonics, and neutral current of a three-phase four-wire system and to take part in power factor correction. The proposed approach is validated through MATLAB/SIMULINK-based (The MathWorks, Natick, Massachusetts, USA) simulation and the results are discussed.

ENGLISH

Power quality problems like voltage sag/swell, flickers, interruptions, voltage distortions and imbalance can have drastic effects on home appliances, industries, processing plants and other applications. In this paper, a novel multi-converter unified power quality conditioner (MC-UPQC) is proposed for simultaneous compensation of voltage and current in multibus/multifeeder distribution systems. A MC-UPQC is a combination of one shunt active power filter (APF) and two or more series APFs. MC-UPQC can be applied to adjacent feeders to compensate for supplyvoltage and load current imperfections on the main feeder and full compensation of supply voltage imperfections on the other feeders. In this paper, a two feeder MC-UPQC is used, which has one shunt APF and two series APFs. All APFs are connected back to back on the DC side and share a common DC link capacitor. As control of this DC link capacitor is very critical for the better performance of MC-UPQC, a novel hybrid fuzzy-PI controller is designed, which is more robust to parameter changes, is non-linear and has a fast dynamic response along with superior steady state response. Through simulation results, it is shown that the hybrid fuzzy-PI controller has performed very well and MC-UPQC is able to compensate supply voltage and load current imperfections on feeder1 and fully protect the sensitive/critical load on feeder2 against distortion, sag/swell, and interruption.

Performance Analysis of Multi Converter Unified Power Quality Conditioner with Dual Feeder System using Fuzzy Logic Control

Many customers who require high reliable power, utilities provide dual feeds; i.e. service to a facility comes from two independent transmission lines. Maintaining power quality is an important issue in the transmission and sub transmission system. Unified Power Quality Conditioner is the optimal solution to ameliorate the quality of power. Many researchers analyzed the performance of UPQC with various control techniques. Recent advanced UPQC is the Multi Converter Unified Power Quality Conditioner (MCUPQC). Conventionally the MC-UPQC is controlled using the PI controller for DC link voltage control. This paper proposes Fuzzy Logic Controller (FLC) to enhance the performance of the MC-UPQC to improve the power quality in a multi bus with sub transmission system. In this article MC-UPQC is designed with two series and one shunt voltage-source converters (VSC). It is nominated to follow out in adjacent transmission lines to improve the quality of electric potential. In the proposed system, all converters are connected back to back on the dc side and share a common DC-link capacitor. It results in the transfer of power from one line to adjacent line to compensate for voltage sag/swell. Performance of MC-UPQC using the conventional PI controller and proposed FLC are compared. Harmonics produced by voltage distortion is also reduced within IEEE standards. The whole system is simulated and analyzed using MATLAB7.7/ Simulink.

A New Control Strategy with Fuzzy Logic Technique in Distribution System for Power Quality Issues

A new control structure for two feeders, three phase four wire distribution systems (3P4W) operating with multi-converter unified power quality conditioner (MC-UPQC) is proposed in this paper. The modified synchronous reference frame theory (MSRF) is mainly used in the new controller design. The proposed system is designed and applied for two feeders of 3P4W with UPQC. This system associated with three voltage source converter which is connected commonly to two feeder distribution systems. Under linear and nonlinear load conditions, the proposed control scheme is simulated with 3P4W and it is efficiently compensate the voltage sag and reduce the total harmonics distortion. The fast dynamics response of dc link capacitor is achieved with the help of FLC controller (Fuzzy logic controller). The neutral current flowing in series transformers of the two feeders is zero with the implementation of proposed system.

An Efficient Control Strategy Based Multi Converter UPQC using with Fuzzy Logic Controller for Power Quality Problems

A custom power device provides an integrated solution to the present problems that are faced by the utilities and power distribution. In this paper, a new controller is designed which is connected to a multiconverter unified power quality conditioner (MC-UPQC) for improving the power quality issues adopted modified synchronous reference frame (MSRF) theory with Fuzzy logic control (FLC) technique. This newly designed controller is connected to a source in order to compensate voltage and current in two feeders. The expanded concept of UPQC is multi converter-UPQC; this system has a two-series voltage source inverter and one shunt voltage source inverter connected back to back. This configuration will helps mitigate any type of voltage / current fluctuations and power factor correction in power distribution network to improve power quality issues. In the proposed system the power can be conveyed from one feeder to another in order to mitigate the voltage sag, swell, interruption and transient response of the system. The control strategies of multi converter- UPQC are designed based on the modified synchronous reference frame theory with fuzzy logic controller. The fast dynamics response of dc link capacitor is achieved with the help of Fuzzy logic controller. Different types of fault conditions are taken and simulated for the analysis and the results are compared with the conventional method. The relevant simulation and compensation performance analysis of the proposed multi converter-UPQC with fuzzy logic controller is performed.

A New Control Strategy Based Multi Converter UPQC Using Fuzzy Logic Controller to Improve the Power Quality Issues

A design of multiconverter unified power quality conditioner to improve the power quality issues is presents in this paper. Modified SRF theory and fuzzy logic controller technique are incorporated in this modelling. This newly designed controller is connected to a source in order to compensate voltage and current in the two feeders. The expanded concept of UPQC is multi converter-UPQC; this system has two series voltage source converter (VSC) and one shunt VSC connected back to back. In the proposed system, the power can be conveyed from one feeder to another in order to mitigate the voltage sag, swell, interruption and transient response of the system. The control strategies of multi converter-UPQC are designed based on the modified synchronous reference frame theory with fuzzy logic controller. The transient response of the fuzzy logic controller in dc-link voltage controller will be very fast. The relevant simulation and compensation performance analysis of multi converter-UPQC with fuzzy logic controller is performed using MATLAB/Simulink software.

Design of Two Feeder Three Phase Four Wire Distribution System Utilizing Multi Converter UPQC with Fuzzy Logic Controller

This paper proposes the instantaneous p-q theory based fuzzy logic controller (FLC) for multi converter unified power quality conditioner (MC-UPQC) to mitigate power quality issues in two feeders three-phase four-wire distribution systems. The proposed system is extended system of the existing one feeder three-phase four-wire distribution system, which is operated with UPQC. This system is employed with three voltage source converters, which are connected commonly to two feeder distribution systems. The performance of this proposed system used to compensate voltage sag, neutral current mitigation and compensation of voltage and current harmonics under linear and nonlinear load conditions. The neutral current flowing in series transformers is zero in the implementation of the proposed system. The simulation performance analysis is carried out using MATLAB.

Improving Power Quality in a Multi bus Multi Feeder System Using MC-UPQC

A b s t r a c t : This paper presents a new Unified Power-Quality Conditioning System (MC-UPQC), capable of simultaneous compensation for voltage and current in multi-bus/multi-feeder systems. By using one shunt Voltage-Source Converter (VSC) and two or more series VSCs the configuration is made. The system can be applied to adjacent feeders to compensate for supply-voltage and load current imperfections on the main feeder and full compensation of supply voltage imperfections on the other feeders. The configuration will be designed as all converters are connected back to back on the dc side and share a common dc-link capacitor. The system is also capable of compensating for interruptions without the need for a battery storage system and consequently without storage capacity limitations. By the simulation the performance of MC-UPQC as well as the adopted control algorithm will be illustrated. Index- terms: Voltage-Source Converter (VSC), Interline Power Flow Controller (IPFC), Unified PowerQuality Conditioning System (UPQC), I. Introduction When the power flows of two lines starting in one substation need to be controlled, an Interline Power Flow Controller (IPFC) can be used. An IPFC consists of two series VSCs whose dc capacitors are coupled. This allows active power to circulate between the VSCs. With this configuration, two lines can be controlled simultaneously to optimize the network utilization. The GUPFC combines three or more shunt and series converters. It extends the concept of voltage and power-flow control beyond what is achievable with the known two-converter UPFC. The simplest GUPFC consists of three converters—one connected in shunt and the other two in series with two transmission lines in a substation. The basic GUPFC can control total five power system quantities, such as a bus as well. By using GUPFC devices, the transfer capability of transmission lines can be increased significantly. Furthermore, by using the multiline-management capability of the GUPFC, active power flow on lines cannot only be increased, but also be decreased with respect to operating and market transaction requirements. In general, the GUPFC can be used to increase the transfer capability and relieve congestions in a flexible way. This concept can be extended to design multiconverter configurations for PQ improvement in adjacent feeders. For example, the interline unified power-quality conditioner (IUPQC), which is the extension of the IPFC concept at the distribution level, has been proposed in the IUPQC consists of one series and one shunt converter. It is connected between two feeders to regulate the bus voltage of one of the feeders, while regulating the voltage across a sensitive load in the other feeder. In this configuration, the voltage regulation in one of the feeders is performed by the shunt-VSC. However, since the source impedance is very low, a high amount of current would be needed to boost the bus voltage in case of a voltage sag/swell which is not feasible. It also has low dynamic performance because the dc-link capacitor voltage is not regulated. In this paper, a new configuration of a UPQC called the multiconverter unified power-quality conditioner (MC-UPQC) is presented. The system is extended by adding a series-VSC in an adjacent feeder. The proposed topology can be used for simultaneous compensation of voltage and current imperfections in both feeders by sharing power compensation capabilities between two adjacent feeders which are not connected. The system is also capable of compensating for interruptions without the need for a battery storage system and consequently without storage capacity limitations.