Abstract— In this paper presents Three-phase unifiedPowerQuality (UPQC) to improve powerquality. The UPQC is realized by the integration of series and shunt active power filters (APF) sharing a common dc bus capacitor. The realization of shunt APF is carried out using a three-phase Voltage Source Inverter (VSI), The performance of the applied control algorithm is evaluated in terms of power- factor correction, source neutral current mitigation, load balancing, and mitigation of voltage and current harmonics in a three-phase, four-wire distribution system for different combinations of linear and non- linear loads. Dynamic Voltage Restorer (DVR) is presented to improve the Powerquality in distribution system by injecting voltage in series for the protection of sensitive loads against voltage sags and voltage swells. The performance of the DVR depends on control technique involved .This circuit consists of capacitor in series with the interfacing inductor of the shunt active filter. The series capacitor enables reduction in dc-link voltage requirement of the shunt active filter and simultaneously compensating the reactive power required by the load, so as to maintain unity power factor, without compromising its performance. This allows us to match the dc-link voltage requirements of the series and shunt active filters with a common dc- link capacitor. AC induction motor has a fixed in the output side to run the ac machine with required speed. The proposed topology enables UPQC to
ABSTRACT: In this paper Fuzzy based Interline UnifiedPowerQuality Conditioner (iUPQC) for powerquality enhancement. A Fuzzy Logic Controller (FLC) is based on fuzzy sets and fuzzy rules with their membership functions of inputs and outputs. A control technique of two active filters is to control the sinusoidal reference. In iUPQC; Series Active Filter (SAF) works as a current source and Parallel Active Filter (PAF) works as a voltage source and due to these there is a high and low impedances occurs which is indirectly compensates the harmonics and disturbances of the grid voltage and load current and also impedance path is low harmonic at load current. To deal with sinusoidal reference for well-known frequency spectrum, a technique of pulse width modulation (PWM) is used. A simulation design control, power flow analysis is proposed in interline unifiedpowerquality controller (iUPQC) and to eliminate harmonics using a Fuzzy Logic Controller (FLC). In this paper is discussed about structure, control and capability of the iUPQC with Fuzzy Controller technique and efficiency is verified through MATLAB Simulation.
In order to meet PQ standard limits, it may be necessary to include some sort of compensation. Modern solutions can be found in the form of active rectification or active filtering. A shunt active power filter is suitable for the suppression of negative load influence on the supply network, but if there are supply voltage imperfections, a series active power filter may be needed to provide full compensation. In recent years, solutions based on Flexible AC Transmission Systems (FACTS) have appeared. The application of FACTS concepts in distribution systems has resulted in a new generation of compensating devices. A UnifiedPowerQuality Conditioner (UPQC) is the extension of the UnifiedPower-Flow Controller (UPFC) concept at the distribution level. It consists of combined series and shunt converters for
ABSTRACT:In power system networks powerquality problem may come from load side or source side. Load side problems causes harmonics and reactive power issues and source side problems cause voltage stability problems. Powerquality improvement for sensitive load by a unifiedpowerquality conditioner (UPQC) with a distribution system is conferred. UPQC consists of series and shut compensators for compensation of voltage disturbances and current disturbances. Till now various control strategies are proposed for shunt and series compensators. In this paper the instantaneous unit vector control theory under various loading conditions is analysed. With the proper control strategy UPQC can compensate the harmonic and reactive power of the load. MATLAB/SIMLINK based model is developed and simulation results are presented for various loading condition.
This paper presents a control strategy for a three phase unifiedpowerquality (UPQC) for an improvement of different powerquality problems. The UPQC is realized by integration of series and shunt compensation system. The shunt and series system is realized using a three phase, three leg voltage source inverter (VSI). A control technique based on unit vector tempulate technique (UTT) is used to get the reference signals for transmission line, while Icosφ algorithm is used for the control of shunt, series transsformer. The performance of the implemented control algorithm is evaluated in terms of voltage sag, swell and voltage dip in a three phase transmission system for different combination of linear and non linear loads. In this control method, the current voltage control is applied over the fundamental supply currents/voltage instead of fast changing current s voltages, thereby reducing the computational delay and the required sensors. MATLAB simulink based simulations results are obtained, which support the functionality of the UPQC.
ABSTRACT: This project presents a powerquality improvement using unifiedpowerquality conditioner (UPQC) to compensate current and voltage quality problems of sensitive loads. The UPQC consists of the series and shunt converter having a common dc link. The series converter mitigates voltage sag from the supply side and shunt converter eliminates current harmonics from the non-linear load side. The developed controllers for series and shunt converters are based on a reference signal generation method (phase-locked loop). The dc link control strategy is based on the fuzzy-logic controllers. The conventional method using dq transformation to show the superiority of the proposed sag detection method. A fast sag detection method is also is presented. The efficiency of the proposed system is tested through simulation studies using the MATLAB/SIMULINK environment.
The proposed Dual unifiedpowerquality was able to compensate the nonlinear load currents and also ensure the sinusoidal voltage for the load in all three phases. The control also had a great performance during the load steps and voltage disturbances at the source. The main advantage of the proposed control in relation to other proposed schemes were the utilization of sinusoidal references for both series and shunt active filter controls without the need for complex calculations or coordinate transformations. It minimizes the total harmonic content in load voltages to maintain the powerquality within IEEE-519 standards.
ABSTRACT: The growth of electricity demand and the increased number of non-linear loads in power grids, providing a high quality electrical power should be considered. A new component within the flexible AC-transmission system (FACTS) family, called unifiedpowerquality conditioner (UPQC) is presented in this paper. The UPQC is derived from the unifiedpower flow controller (UPFC). The unifiedpowerquality conditioner (UPQC) is being used as a universal active power conditioning device to mitigate both current and voltage harmonics at a distribution side of power system network. The active power exchange between the shunt and series converters, which is through the common dc link in the UPFC, is now through the transmission lines at the third-harmonic frequency. In this paper, the capability of UPQC with fuzzy logic controllers (FLC) is observed for the power system network. The proposed fuzzy logic controller (FLC) in UPQC is capable of providing good static and dynamic performances. On comparing with and without UPQC, the performance is observed. Application of UPQC with fuzzy logic controller in powerquality enhancement is simulated in Matlab/Simulink environment which show the effectiveness of the proposed structure.
The Usage of powerquality conditioners in the distribution system network has increased during the past years due to the steady increase of nonlinear loads connected to the Electrical grid. The current drained by nonlinear loads has a high harmonic content, distorting the voltage at the utility grid and consequently affecting the operation of critical loads. By using a unifiedpowerquality conditioner (UPQC) it is possible to ensure a regulated voltage for the loads, balanced and with low harmonic distortion and at the same time draining undistorted currents from the utility grid, even if the grid voltage and the load current have harmonic contents. The UPQC consists of two active filters, the series active filter (SAF) and the shunt or parallel active filter (PAF). The PAF is usually controlled as a non sinusoidal current source, which is responsible for compensating the harmonic current of the load, while the SAF is controlled as a non sinusoidal voltage source, which is responsible for compensating the grid voltage. Both of them have a control reference with harmonic contents, and usually, these references might be obtained through complex methods. The line conditioner consists of two single- phase current source inverters where the SAF is controlled by a current loop and the PAF is controlled by a voltage loop. In this way, both grid current and load voltage are sinusoidal, and therefore, their references
Abstract : UnifiedPowerQuality Conditioner (UPQC) is combination of shunt and series active power filter which are used in distribution system to control the voltage related problem such as voltage harmonics, voltage flicker, voltage sag-swell and current related problem such as current harmonics, Reactive current and current unbalance. By Studying the performance of UPQC using Instantaneous active and reactive power theory (p-q) for shunt active power filter and synchronous reference frame theory (d-q) for series active power filter to generate the reference signal for voltage and current. The hysteresis controller is used to generate the gating signal for shunt voltage source inverter connected to the sensitive load and non-liner load. The sinusoidal pulse width modulation techniques (SPWM) are used to generate the gating signal for series voltage source inverter which is connected to the feeder through series injection transformer. The PI controller are used to generate signal to compensate the errors. Energy storage element such as battery is not required for unifiedpowerquality conditioner. The MATLAB/SIMULATION model of unifiedpowerquality conditioner (UPQC) is used to improvement of powerquality problem at distribution network.
ABSTRACT: The unifiedpowerquality conditioner (UPQC) is a power conditioning device. The UPQC with the combination of series active power and shunt active power can improve the powerquality at the point of common coupling on power distribution systems under unbalanced and distorted load conditions. In this paper, synchronous- reference frame (SRF)-based control method to compensate power-quality (PQ) problems through a three-phase four- wire distribution system is proposed. For series active filter and shunt active filter SPWM controller used to produce insulated-gate bipolar transistor (IGBT) switching signals and to compensate all voltage-related problems, such as voltage harmonics, sag, swell, voltage unbalance, etc., at the PCC. The simulation results based on Matlab/Simulink are discussed in detail to support the SRF-based control method presented in this paper. The proposed approach is also validated through experimental study with the UPQC hardware prototype.
Abstract - This paper present an analysis on the unifiedPowerquality conditioner (UPQC) to improve the electric powerquality at distribution levels. Conventional powerquality mitigation equipment is a providing to be inadequate for an increasing number of applications. Different approaches in compensation and recent developments in fields. Single modern and very promising solution that deal with both load current and supply voltage imperfection is the UnifiedPowerQuality Conditioner (UPQC). This is present a broad overview on different possible UPQC network configuration for 1-phase (two wires) and 3-phase (three-wire and four-wire networks).
The quality of the Electrical power is effected by many factors like harmonic contamination, due to non-linear loads, such as large thyristor power converters, rectifiers, voltage and current flickering due to arc in arc furnaces, sag and swell due to the switching of the loads etc. One of the many solutions is the use of a combined system of shunt and active series filters like unifiedpowerquality conditioner (UPQC) This device combines a shunt active filter together with a series active filter in a back- to-back configuration, to simultaneously compensate the supply voltage and the load current or to mitigate any type of voltage and current fluctuations and power factor correction in a power distribution network. The present work study the compensation principle and different control strategies used here are based on PI & ANN controller of the UPQC in detail. The control strategies are modeled using MATLAB/SIMULINK. The simulation results are listed in comparison of different control strategies and for the verification of results.
The ever increasing use of solid state technology in industrial and domestic applications is extensively contributing towards line current harmonics, non- linear voltage drops, cables overheating, poor power factor and more power losses at distribution levels. To mitigate these problems and maintain the reliability of the delivered power within acceptable margins, stringent power qualit y standards are put into practice. The adherence to these standards can be achieved with a custom power device such as the unifiedpowerquality conditioner (UPQC). Being an adaptable and flexible power electronic device, UPQC has become the most appealing solution to powerquality problems at the distribution level.
Abstract: The theory and modelling of unifiedpowerquality conditioner(UPQC),which is a FACTS device is presented in this paper. The model consists of thyristor controlled capacitor banks, series-active filter and shund active filter. The series-active and shunt-active filters mainly compensates negative-sequence current and harmonics and the thyristor controlled capacitor banks is used to compensate the reactive power of power frequency. The UPQC is modelled using Simulink and is simulated using a software called MATLAB.
For eliminating all the problems related to powerquality, the custom power devices are used [6-8]. There are various custom power devices such as, dynamic voltage restorer (DVR), distribution static compensator (DSTATCOM) and unifiedpowerquality conditioner (UPQC). DVR is series connected device which eliminates the voltage related problems such as voltage swell/sag. The DSTATCOM is connected in parallel and eliminates the load related powerquality issues . UPQC is the combination of series and shunt compensators. Further classification of UPQC depends on its topologies, position of shunt compensators and control techniques. The classification of UPQC is explained in .
Generally, this paper proposes technique of FACTs based controller called as unifiedpowerquality conditioner, which is used to mitigate problems on transferring power based voltage and currents in the distribution systems. Reducing the rating of dc-link voltage without compromising the compensation technique is one of the advantages of unifiedpowerquality conditioner technique. The series and shunt controllers as series connection with the combination of capacitor and inductor for filtering process, and the system neutral is also considered and directly connected to neutral of distribution system for avoiding the utilization of fourth leg in the shunt converter voltage source inverter. This paper also presents a concept for improving powerquality of a power distribution system such as an ANN logic controller along with the UPQC control strategy. The simulation results are compared for both conventional PI controller and ANN controller.
Abstract- Due to vast implementation of power electronics based equipment powerquality has turned into essential and important factor. The conventional devices or equipment is not sufficient for enhancing the powerquality. The UPQC is the new design for improving the powerquality and moreover it attends to both voltage deformity and current deformity simultaneously. In this paper new FACTs (flexible Alternating current Transmission) circuit called UPQC (unifiedpowerquality conditioner) is developed to compensate the voltage and current imperfections. The two different control strategies are used for it. The voltage sag and swells together with current harmonic compensation are shown.
Now a day’s power electronics devices are used because of technological improvement..The increasing number of power electronics loads generally used in industry because of this load powerquality problem arises. According to this consideration of power electronic load require ideal sinusoidal supply voltage for proper system operation. They are responsible for abnormal condition in distribution system. According to this scenario different mitigating technique are implemented over the years. Some of solution involves flexible compensator known as improved unifiedpowerquality controller .by using this controller we can compensate voltage sag/swell. also provide reactive power .this paper presents new control technique for iupqc. In that pulse width modulation control is used in it .it is achieved by using voltage and current sinusoidal references. The experimental results verified by using improved unifiedpowerquality controller. The grid-voltage regulation was achieved by taking different load conditions. These results have demonstrated a suitable performance of voltage regulation at both sides of the iUPQC, even while compensating harmonic current and voltage imbalances.
This paper deals with a UnifiedPowerQuality Conditioner (UPQC) for load balancing, power factor- correction, voltage regulation, voltage and current harmonics mitigation, mitigation of voltage sag, swell and voltage dip in a three-phase three-wire distribution system for different combinations of linear and non- linear loads.The unifiedpowerquality conditioner (UPQC) is a combination of back to back connected shunt and series active power filters (APFs) to a common DC link voltage, which compensates voltage and current based distortions, independently.Using instantaneous active and reactive Power theory ,harmonic detection, reactive power compensation, voltage sag and swell have been simulated and the results are analyzed. The operation and capability of the proposed system was analyzed through simulations with MATLAB / SIMULINK.