Load Voltage Harmonics Research Articles

Hybrid controller-based solar-fuel cell-integrated UPQC for enrichment of power quality

Abstract A fuzzy-integrated sliding mode-based hybrid controller (FISMHC) attributed to unified power quality conditioner (UPQC) was proposed in this study through implementation with solar integrated to fuel cell through incorporation of UPQC within sequence designed for active power filters of series and shunt configurations under shared structure of DC-link capacitor deployment. Furthermore, the proposed scheme with FISMHC UPQC (U-FISMHC) can achieve the following goals: (i) maintaining constant DC-link voltage in the absence of peak overshoot, (ii) performance evaluation under varied fluctuations in grid voltage, and (iii) decreasing source current and load voltage harmonics. In addition, the study compares U-FISMHC performance with distribution case over specific test conditions such as supply voltages, solar irradiation, and conditioned loads to demonstrate the proposed controller’s superior performance.

Harmonic Voltage Control in Distributed Generation Systems Using Optimal Switching Vector Strategy

With increased penetration of renewable power and the nonlinear loads in the distributed generation (DG) systems, increased power quality concerns are exhibited in the active distribution networks, especially the challenges associated with the current and voltage harmonics in the system. Various conventional harmonic compensation techniques are developed for voltage-controlled DG inverters in past, majority involve either multiple proportional-integral (PI) or proportional-resonant (PR) controllers in eliminating grid current harmonics. The current-controlled inverters, on the other hand, are not preferred in industrial applications, accounting to their wide variations in the switching frequency. A novel and adaptive harmonic voltage control is developed here, for voltage-controlled DG inverters, which neither uses any PI regulators nor imposes stability issues associated with nonideal implementation of infinite gains of PR controllers. Interestingly, the developed control logic can be used for DG inverters, both in grid-connected and off-grid operational modes. Furthermore, this strategy allows a network operator to use this as an additional supplement that can be enabled/disabled as per the network requirement. The control logic exploits the property of an optimal-switching-vector controller, i.e., accurate output voltage tracking. Simulations results demonstrate the effectiveness of the controller, to suppress grid current harmonics and load voltage harmonics in grid-interfaced (GI) and off-grid modes, respectively, ultimately satisfying the mandatory IEEE standard-1547. Experimental results verify the viability of the controller for practical applications.

Dynamic voltage restorer using sliding mode controller: Experimental studies

The simulation and implementation of a sliding mode control strategy for a single-phase dynamic voltage restorer (DVR) to mitigate load voltage sag swell and harmonics is presented in this work. The control strategy's goal is to compensate for the required voltage by regulating the DVR's voltage via an injection transformer while keeping the load voltage constant. The ability of the DVR to achieve a good performance greatly depends on its control strategy. The controller used in this work is based on SMC theory, which consists of creating a passivation output and a storage function to use as a function of Lyapunov. The proposed control scheme of the DVR is initially evaluated in simulations using MATLAB and validated using a laboratory-scale prototype of the entire system, including a source, the DVR circuit and a load. The control scheme is implemented on a dSPACE 1104 board and the MATLAB real-time toolbox. Both the experimental results have demonstrated the effectiveness the proposed control strategy of DVR in mitigating power qualities issues and therefore enhancing the performance of the network.

Dynamic voltage restorer using sliding mode controller: Experimental studies

The simulation and implementation of a sliding mode control strategy for a single-phase dynamic voltage restorer (DVR) to mitigate load voltage sag swell and harmonics is presented in this work. The control strategy's goal is to compensate for the required voltage by regulating the DVR's voltage via an injection transformer while keeping the load voltage constant. The ability of the DVR to achieve a good performance greatly depends on its control strategy. The controller used in this work is based on SMC theory, which consists of creating a passivation output and a storage function to use as a function of Lyapunov. The proposed control scheme of the DVR is initially evaluated in simulations using MATLAB and validated using a laboratory-scale prototype of the entire system, including a source, the DVR circuit and a load. The control scheme is implemented on a dSPACE 1104 board and the MATLAB real-time toolbox. Both the experimental results have demonstrated the effectiveness the proposed control strategy of DVR in mitigating power qualities issues and therefore enhancing the performance of the network.

Hybrid Reference Current Generation Theory for Solar Fed UPFC System

The extensive usage of power electronic components creates harmonics in the voltage and current, because of which, the quality of delivered power gets affected. Therefore, it is essential to improve the quality of power, as we reveal in this paper. The problems of load voltage, source current, and power factors are mitigated by utilizing the unified power flow controller (UPFC), in which a combination of series and shunt converters are combined through a DC-link capacitor. To retain the link voltage and to maximize the delivered power, a PV module is introduced with a high gain converter, named the switched clamped diode boost (SCDB) converter, in which the grey wolf optimization (GWO) algorithm is instigated for tracking the maximum power. To retain the link-voltage of the capacitor, the artificial neural network (ANN) is implemented. A proper control of UPFC is highly essential, which is achieved by the reference current generation with the aid of a hybrid algorithm. A genetic algorithm, hybridized with the radial basis function neural network (RBFNN), is utilized for the generation of a switching sequence, and the generated pulse has been given to both the series and shunt converters through the PWM generator. Thus, the source current and load voltage harmonics are mitigated with reactive power compensation, which results in attaining a unity power factor. The projected methodology is simulated by MATLAB and it is perceived that the total harmonic distortion (THD) of 0.84% is attained, with almost a unity power factor, and this is validated with FPGA Spartan 6E hardware.

Voltage quality improvement in electrical distribution networks using dynamic voltage restorers: design, simulation and experimental tests of a robust controller

This paper presents a simulation and implementation of a proportional integral (PI) and adaptive neuro-fuzzy inference system (ANFIS) control scheme of single-phase dynamic voltage restorer (DVR) for the mitigation of load voltage sag, swell and harmonics. The objective of the control strategies is to regulate the voltage of the DVR via an injection transformer to compensate for the voltage required and maintain the load voltage at a constant value. However, the conventional compensation techniques are grouped only on the load voltage and the DVR itself. The aim is to regulate the injection voltage of the DVR to compensate the grid voltage via the injection transformer in addition to maintaining the load voltage stable. These methods have been adapted to sinusoidal references and is resistant to sags, swells and harmonics. The proposed control strategies of the DVR are initially evaluated in simulations under MATLAB/Simulink and then validated on a laboratorial prototype of the single-phase DVR. n in-depth analysis across different controllers would show the performance and their robustness in mitigating network power quality issues. The robustness of the proposed ANFIS controller is examined by comparative studies with the PI controller. We notice that the proposed ANFIS controller was able to obtain a lower total harmonic distortion than that of the PI method.

Power Quality Improvement in Integrated System using Inductive UPQC

Harmonics pollution is very dangerous in medium power applications. Generally, harmonics are produced in the system due to the connection of nonlinear loads. This article presents a novel load voltage and current harmonic compensation, voltage sag and swells compensation approach using hybrid UPQC. The proposed synchronous reference controller uses the Carrier Pulse Width Modulation (CPWM) technique for the proper control of UPQC. The simulations are carried on Matlab/Simulink platform. The output results present the proposed hybrid UPQC compensates the load current harmonics, voltage sag and swell effectively. The load voltage harmonics are reduced from 11.65% to 1.53% and the current harmonics are reduced from 30.97% to 2.24% respectively. https://dorl.net/dor/20.1001.1.13090127.2021.11.2.6.5

Analysis of distribution systems in the presence of nonlinear load and substation voltage harmonics

Analysis of distribution systems in the presence of nonlinear load and substation voltage harmonics

Economic assessment of non-sinusoidal energy in distorted distribution systems

PurposeThe purpose of this paper is to analyze annual energy expenditure in the presence of non-linear load and substation voltage harmonics in distribution systems. Economic assessment of non-sinusoidal energy is a challenging task that involves complex computations of harmonic load powers and harmonic line losses.Design/methodology/approachThe paper evaluates fundamental and non-sinusoidal components of electrical energy by applying backward/forward sweep technique in distorted distribution systems. This work involves harmonic power computations at the substation by including harmonic losses occurring in various lines of the distribution system.FindingsThe paper found that annual energy expenditure significantly depends upon the non-linear load, supply voltage harmonics and type of tariff structure considered in the distribution system. Impact of individual harmonic orders on the energy billing is also assessed.Originality/valueThe paper concludes that considering harmonic distortions in the distribution system analysis would help electricity regulators formulate adequate pricing structures, which would further generate appropriate economic signals for electricity utility and the consumers.

IMPROVEMENT OF POWER QUALITY USING PQ THEORY BASED SERIES HYBRID ACTIVE POWER FILTER

This paper investigate the power quality improvement under unbalanced supply condition. The current drawn is highly non-linear and contain harmonics. Shunt active filter eliminate only the current harmonics, not the voltage harmonics. But he series active filter provide harmonics isolation. SHAPF is suitable for compensation of source voltage, reactive power and reduce source current and voltage harmonics. It also eliminate series and parallel resonance. The control technique for the SHAPF is based on the Generalized Instantaneous Reactive Power Theory. The real and reactive power are converted into voltage component. Then the reference voltage are calculated inorder to compensate the source current and load voltage harmonics. Simulations have been carried out on MATLAB-Simulink Platform and results are presented.

Power System Compensation Using a Power-Electronics Integrated Transformer

This paper presents a new transformer, that is, the custom power active transformer (CPAT)—which integrates shunt and series equivalent circuits within the transformer's magnetic structure. Thus, it provides power system services using a single transformer. The CPAT equipped with a power converter can be utilized in distribution systems to control grid current and load-voltage waveforms while operating as a step-up or step-down transformer between the grid and load. Moreover, it can provide other services that any typical shunt-series compensation arrangement provides. The design and analysis of a single-phase CPAT are presented, showing the effect of coupling between windings and transformer parameters affecting CPAT operation. In this paper, control of the CPAT in a unified power-quality controller application is investigated to attenuate grid-current and load-voltage harmonics as well as compensate for reactive power requirements and mitigate grid inrush current. Through simulation and experimental implementation, the merits and performance of the CPAT were validated.

A Novel Control Strategy Based Dynamic Voltage Restorer for Compensation of Voltage Harmonics in Distribution System

Power quality is one of the areas that the power sector is worried about. Power quality is the measure of practical system resemblance to ideal system. Voltage quality can be defined as the maintenance of voltage waveform shape close to ideal shape with proper magnitude and frequency. Even a slight change in voltage of the system can cause serious damage to the power system. Sensitive loads cannot adjust for small change in voltage. This paper presents Dynamic Voltage Restorer (DVR) for voltage harmonic suppression along with sag/swell compensation in distribution system. DVR is a voltage source converter which sends compensating signals when operated through switches of voltage source converter. This paper presents a novel control strategy to control DVR to block out the voltage harmonics in distribution system. The models and results are developed using MATLAB/SIMULINK software and comparative analysis of source voltage harmonics and load voltage harmonics during sag/swell compensation was tabulated.

Study of Unified Power Quality Conditioner for Power Quality Improvement

These In a powers system network there are many problems related to power quality. So to improve power quality of a system we use different devices such as active power filters. Active power filters are classified into two types that is Shunt Active Power Filter (APF) and Series Active Power Filter (APF) and combination of both is known as UPQC (Unified Power Quality Conditioner). Here we have done simulation of Shunt Active Power Filter, Series Active Power Filter and Unified Power Quality Conditioner. Shunt APF is used to mitigate the problems due to current harmonics which is because of non-linear load and make source current sinusoidal and distortion free. The control scheme used is hysteresis current controller using p-q theory. Series APF is used to mitigate problems caused due to voltage distortion and unbalance present in source voltage and make load voltage perfectly balanced and regulated. The control scheme used is Hysteresis voltage controller by using a-b-c to d-q transformations. Then Shunt APF and Series APF is combined for designing UPQC and by this current harmonics in load current and voltage unbalances in source voltage both are removed and source current becomes sinusoidal and load voltage becomes perfectly balanced.

Experimental Verification of Quasi Z-Source Inverter Based Hybrid Series Active Power Filter for Interconnection of PV into the Utility Grid

This paper proposes a Photovoltaic/Battery interfaced Quasi Z-source inverter based three-phase four-wire Hybrid Series Active Power Filter (HSAPF)to compensate the voltage and current related power quality problem in small distributed power system. The HSAPF consists of shunt passive filter and series active filterconsuming a battery. The shunt active filter mitigates the current harmonics generated by a nonlinear load. The series active filter mitigates the voltage sag/swell and load voltage harmonics, which consumes the power from Photovoltaic (PV) array with quasi Zsource inverter (qZSI). A new controller of qZSI based HSAPF uses two control schemes to boost the PV/Battery output voltage and achieve maximum power point tracking PV array. The simulation and experimental results are presented to validate the performance of proposed qZSI based HSAPF.

Harmonic current and voltage compensation using HSAPF based on hybrid control approach for synchronous reference frame method

Abstract This paper presents a Hybrid Series Active Power Filter (HSAPF) for compensation of source current and load voltage harmonics. The HSAPF combination consists of a small rated series active power filter and a shunt connected passive power filter. This combination is suitable for compensation of voltage-type as well as current-type harmonic producing load. The HSAPF uses the synchronous rotating reference frame method that based on hybrid control approach, which eliminate both source current as well as load voltage harmonics and also tests the performance of HSAPF for ideal voltage, non-ideal voltage and also at different loading conditions, etc.

An experimental assessments on different control techniques of series hybrid active power filter

Summary For high power application of active power filters, series hybrid active power filter (SHAPF) configuration is popular because of its multi-functionality and small capacity inverter requirement. The SHAPF filtering characteristics and efficiency of harmonic compensation depend on the control algorithm applied to calculate the reference voltage. This paper compares the filtering performance of SHAPF using three different control algorithms applied for reference voltage generation. The first control algorithm derives reference voltage proportional to the source current harmonics, where the source current harmonics are separated using the p-q theory. The second control algorithm derives reference voltage from load voltage harmonics separated using the dual p-q theory. The third control algorithm derives reference voltage using vector algebra-based voltage decomposition method in three-phase coordinate system. The mathematical formulation of selected three control algorithms along with their applications to SHAPF is presented. To check the filtering performance of SHAPF with selected control algorithms, an experimental prototype of SHAPF controlled by the ARM Cortex M4 microcontroller STM32F407VGT6 is developed. Experiments are performed to check the performance of SHAPF in compensating current harmonic generating load and voltage harmonic generating load. The results of compensation, the complexity involved in extracting reference, and control algorithm computation time are compared. The comparison shows that the operation of the voltage decomposition method is comparatively better due to fast extraction of the reference voltage. Copyright © 2014 John Wiley & Sons, Ltd.

Derivation of a Stationary-Frame Single-Loop Controller for Three-Phase Standalone Inverter Supplying Nonlinear Loads

In this paper, a stationary-frame, single-loop controller for three-phase standalone inverter supplying nonlinear loads has been derived from synchronous reference frame proportional-integral multiloop controller. In this method, load voltage harmonics are eliminated by a single loop and only one control variable. The proposed method has several advantages such as lack of Park transformation and requires tuning only one control parameter. It can also be implemented with less computational burden, less complexity, and easier tuning, compared to conventional proportional-integral multiloop controller. Experimental results with laboratory prototype under linear and nonlinear load conditions validate the proposed method.

English

This paper presents the application of dynamic voltage restorers (DVR) on power distribution systems for mitigation of voltage sags, harmonics and imbalances at sensitive loads. The dynamic voltage restorer (DVR) has become popular as a cost effective solution for the protection of sensitive loads from voltage sags and swells. It would be advantageous that a DVR could also be used to compensate any steady state load voltage harmonics, since this would increase the Power Quality. The DVR, which is based on a five-level flying-capacitor voltage Source converter (VSC), has been proved suitable for the task of compensating voltage disturbances. The performance of the DVR depends on control technique involved. This paper presents the control system based on the so-called repetitive control. Unlike other control schemes with a comparable range of applicability, only one controller is needed to cancel out all three disturbances simultaneously, while exhibiting good dynamic performance. To evaluate the quality of the load voltage during the operation of DVR, Total Harmonic Distortion (THD) is calculated. MATLAB are used to carry out all modelling aspects of the repetitive controller and test system. Simulation results show that the control approach performs very effectively and yields excellent voltage regulation.

Design criteria of a control strategy for hybrid power filters based on current and voltage detection

Summary A configuration consisting of a combination of a series active filter (APF) with a parallel passive filter has proven to be an efficient system for harmonic elimination of nonlinear loads. The most effective strategy for this configuration determines the APF reference voltage as the addition of two terms, the first proportional to the source current harmonics and the second opposite to the load voltage harmonics, current and voltage detection (CVD). To obtain the first term, an adequate adjustment of the proportionality constant ‘k’ is necessary for the implementation of the control algorithm. In this paper, design criteria to obtain the k values have been established, based on the system state model. Analysis of the resulting model provides the information needed to establish design criteria for the control strategy, both in terms of harmonic filtering and system stability. Finally, an experimental prototype was developed. The usefulness of the compensation equipment is experimentally confirmed in two contrasting situations: sinusoidal supply voltages and distorted supply voltages. Copyright © 2013 John Wiley & Sons, Ltd.

Hardware implementation of series hybrid active power filter using a novel control strategy based on generalised instantaneous power theory

In the area of power quality conditioners, the series hybrid active power filter (SHAPF) has been focused more in recent times because of its multi-functionality and lower inverter rating requirement. Existing control strategies for SHAPF are based on extracting either source current harmonics or load voltage harmonics. In this study, a novel control scheme based on decomposing multiphase voltage vector into different vectors that represent different components of power is proposed for SHAPF. The mathematical formulation of the proposed control scheme with its applications to SHAPF is presented. The validity of the proposed control scheme is verified by simulation as well as experimental study.