Total Harmonic Distortion Value Research Articles

The Effect of Amplitude Modulation Index and Frequency Modulation Index on Total Harmonic Distortion in 1-Phase Inverter

One of the problems that often arise in the conversion process using an inverter is the existence of Total Harmonic Distortion (THD). Harmonics is a symptom of sinusoidal wave formation whose frequency is a multiple of fundamental frequency. Harmonics will cause interference to the system to damage to electrical devices. This paper discusses the effect of modulation index value amplitudo (Ma) and frequency modulation index (Mf) of the value of THD before using the filter. The test was performed using a 1 phase inverter with input variation of the amplitude modulation index and the frequency that was set using PSIM software. The 16 ATMega microcontroller is used as a pulse width modulation (PWM) signal generator. Simulations using a 6 variations value Ma, ie 0.4, 0.6, 0.8 1.0, 1.2, and 1.4, as well as 10 variations of the value of Mf, namely 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100. Based measurement, for Mf are the same, the greater the value of Ma, then the value of THD tends to decrease. Meanwhile, for the same Ma, the greater the value of Mf, then the value of THD tends to decrease.

Effective Utilization of Cascade H Bridge Multi Level Inverter Integrate Social Spider Optimization for Reduced Total Harmonics Distortion

The significance intention of the proposed method is to eliminate total harmonics distortion (THD) in solar photovoltaic cells powered cascaded H-bridge multilevel inverter (CHMLI). This purpose incorporates Newton-Raphson (NR), particle swarm optimisation (PSO), artificial bee colony (ABC), genetic algorithm (GA), cuckoo search (CS) and social spider optimisation (SSO)-based selective harmonic elimination technique for solving a non-linear transcendental equation to obtain optimal switching angle to achieve minimise THD. The foremost goal to reduce THD value beyond IEEE standard allowable limit is to predict optimal switching angle. This prediction is done in offline then it utilises for online simulation process to achieve minimised THD. Amid, aforementioned techniques incorporate with CHMLI; SSO behaves literally better than all other comparative techniques to attain 3.6% of THD in line voltage from the modulation index of 0.95. This customised product development would enhance quality power flow in this power generation.

Effect of voltage harmonics on pulse repetition rate of partial discharges

The objects of the research are partial discharge processes simulated under the influence of non-sinusoidal voltage. In the context of studying the effect of voltage harmonics on partial discharges, the total harmonic distortion can only be used for rough estimation. The reason for this is that the total harmonic distortion does not take into account the phase angles of the individual voltage harmonic components. Under non-sinusoidal voltage with the total harmonic distortion of 10 % and above, the intensity of the partial discharges in the insulation increases. However, at lower values of the total harmonic distortion, the harmonics can also affect the characteristics of the partial discharges. To solve this problem, it is necessary to carry out a study, increasing the number of voltage harmonics taken into account. To do this, it is possible to use the known three-capacitive equivalent circuit for a dielectric with gas cavity, making appropriate changes to the voltage source. The model was studied using voltage harmonic of the fundamental frequency together with voltage harmonics from the 2nd to the 30th order included. It was found that for the fixed amplitude the phase angle of the voltage harmonics has a decisive influence on the number of partial discharge pulses. In the presence of voltage harmonics, this number can be the same as under the influence of a pure sinusoidal voltage. It can also be 14.3 % less and 14.3 % or 28.6 % greater. In all cases, the value of total harmonic distortion remains the same. The possibility of using high-voltage reference inductive voltage transformers for voltage distortion measurements was studied experimentally. It was found that this is expedient for the region of the maximum value of the magnetic permeability of their magnetic cores, which corresponds to a range of 80–120 % of the transformer rated voltage. Mobile laboratories for checking high-voltage transformers on-site with the addition of appropriate equipment can simultaneously be used to measure a number of power quality indices.

Harmonics compensation in industrial power network using Hybrid Active Power Filter (HAPF) in d-q frame

In AC power networks, the use of harmonic and reactive power compensations through active power filters has become emerging aspect of today’s commercial market. With the advancement of new technologies, loads based on power electronics are regularly being used in low and medium voltage distribution systems, which eventually cause the harmonics in the system currents and voltages. The most dangerous harmonics are the later i-e, 3rd , 5th , 7th and so on, which are basically result of current harmonics. They cause degradation in the performance and working of other important power system equipment. In order to mitigate these daunting harmonics, the best option is to use the hybrid power filters which combine the characteristics of both active and passive harmonic filters al-together. The main idea of this research is to model an industrial network and to perform an analysis over the Total Harmonic Distortion (THD) in the power system. The use of Hybrid Active Power (HAPF) kept the THD value well below 8%, as recommended by European Standard EN50160. With the implementation of HAPF, an additional advantage of power factor improvement was also achieved. PQ theorem was used for calculating parameters of hysteresis control used for filter implementation. Results presented in the research paper confirm the efficiency of designed filter because the THDs of both voltage and current were restricted to 2% and the system power factor was improved too. The major contribution of this research is that power quality was improved most economically using P-Q technique through HAPF.

An improved control strategy of 3P4W DVR systems under unbalanced and distorted voltage conditions

This paper proposes an enhanced nonlinear control technique based on a combination of feedback linearization (FBL) and resonant regulators as tracking controllers for three-phase four-wire (3P4W) dynamic voltage restorers (DVR) under unbalanced and distorted source voltages. A nonlinear model of the DVR system with a PWM voltage-source inverter (VSI) and output LC filters in the distribution system containing nonlinear loads is firstly linearized, which then the proportional integral plus resonant (PI + R) regulators are utilized for tracking controllers. In this control scheme, the voltage references of the controlled variables expressed in the d-q-0 synchronous reference frame (SRF) for the DVR system are generated based on an in-phase compensation strategy, which results in the appearance of the second and multiple-sixth order components in the DVR voltage references under the unbalanced and distorted voltages conditions. With the combination of FBL technique and the tracking controllers based on resonant regulators, the DVR system provides an excellent control performance in the transient and steady states for compensating the load voltages with almost zero steady-state errors. The proposed method is validated by the simulation and experimental results, which show that the DVR with the suggested control scheme restores the load voltages at a low THD (total harmonic distortion) value of about 2.3% compared to 7.7%, 6.2%, and 5.4% by the typical PI, PR controllers, and conventional FBL technique, respectively.

MSPWM Based Implementation of Novel 5-level Inverter with Photovoltaic System

This paper proposes a novel 5-level dc-ac converter circuit using with 6 power semiconductor switches. The proposed multilevel inverter generates five-level ac output voltage by implementing Multi-carrier sinusoidal pulse width modulation (MSPWM) technique with reduced number of switches. The voltage stress on each switching devices and common mode voltage can be minimized from the suggested system. The designed system gives better controlled output current and improved output voltage with diminished total Harmonic Distortion value. The operating principles of the proposed inverter are discussed. DC Input for the proposed system is obtained from PV System. Finally, an experimental prototype of the proposed system with 12-V input voltage and 20 V /5 W output is implemented along with simulation output of the waveform to the load. The efficiency and the reduction of harmonic content are discussed.

An Efficient Buck/Buck-Boost Reconfigurable LED Driver Employing SIN2Reference

An efficient buck/buck-boost reconfigurable LED driver based on peak current control is introduced. The driver supports pulse-width modulation (PWM) and pulse-frequency modulation (PFM) operations. The use of a combination of rectified sin and sin2 functions in the reference is introduced for the purpose of improving the power factor (PF) and total harmonic distortion (THD) of buck and buck-boost converters. The optimal reference waveform shape for buck and buck/boost modes can be set externally. The design ensures that the peak of the inductor current maintains a constant level that is invariant for different ac line voltages. The LED driver has been implemented in a 130-nm CMOS process. PF and THD are improved when the proposed reference is employed, and the peak PF and lowest THD values are 0.995/0.983/0.996 and 7.8/6.2/3.5% for the buck (PWM), buck (PFM), and buck-boost (PFM) cases, respectively. The corresponding peak efficiency for the three cases is 88/92/91%, respectively.

Design Improvisation for Reduced Harmonic Distortion in a Flux Pump-Integrated HTS Generator

This paper presents a design improvisation of a flux pump-integrated 10 kW high-temperature superconducting (HTS) proof of concept generator for reduced harmonic distortion. To carry out the design improvisation, a finite element analysis (FEA) model of the 10 kW HTS generator is developed, and time-stepped magnetic transient simulations are conducted on the 2D model. The effects of stator yoke material, winding pitch factors, and load configurations on total harmonic distortion (THD) are investigated. The results showed that fibre-reinforced polymer (FRP) epoxy (G10) can be used as the stator yoke material to effectively avoid the hysteresis and eddy current losses. In addition, the study results show that for the non-conventional design of the machine, a winding pitch of 2/3 and the armature-load configuration of Star-Delta gives THD values within the standard limit defined by IEEE Standard 519-2014. The THD values indicate that the machine design configuration is suitable for the development of machines for both stand-alone and grid-connected operations, according to IEEE STD 519-2014.

Modeling and Control of Three-Phase Grid-Connected Power Supply With a Small DC-Link Capacitor for Electrolyzers

In this paper, a new feed forward dc-link voltage compensation method is proposed. The target applications are the converters built with diode bridge frontends, small capacitance in the dc-link which feeds a dc/dc converter used for electrolysis. The compensation method can be tuned in a way to minimize the grid side total harmonic distortion (THD) and partial weighted harmonic distortion (PWHD): thus, the converter can comply with the standards with less filtering at the grid side. In order to design the controllers and perform stability analysis, average model has been derived. However, the performance of the proposed control method is a trade-off between the size of the line filter, the value of the line current THD and PWHD, and the amplitude of the load current ripple. The theoretical work has been validated through experiments on a 5 kW dc power supply used for an electrolyzer. In the experiments, the THD of the grid current can be reduced from 30.5% to 29.5% (without filter and including compensation) and 28.5% (with filter and compensation), and the PWHD from 50% to 38.9% by applying the proposed method and also keeping the load current peak-to-peak ripple under 10% of its nominal value.

Reduction of Total Harmonic Distortion (THD) on Multilevel Inverter with Modified PWM using Genetic Algorithm

In this research, modified PWM has been applied to the multilevel inverter (MLI) single-phase three-level diode clamp full bridge. Modified PWM is performed to produce minimum Total Harmonic Distortion (THD) the voltage because the quality of the good voltage is indicated by small THD. The THD indicates the quality of AC voltage source. The THD standard by the IEEE STD 519-1992 Harmonic Voltage Limits is 5% and the Pacific Corp standard is 8%, if the THD value is greater than the THD standard it can cause the electronic load to be damaged due to the damaged waveform. Modified PWM is applied by adding a 50 Hz sinusoidal reference signal with a sinusoidal signal which has a certain amplitude, frequency and phase shift angle. The frequency of the adder signal is the frequency at which the value of the individual harmonic voltage appears (n harmonic). To get maximum result, optimization using Genetic Algorithm (GA) method to determinate amplitude & phase shift angle done. The result of implementation hardware with modified PWM shows smaller THD voltage compared to the THD voltage with Sinusoidal Pulse Width Modulation (SPWM) switching up to 0.19 or decrease 65,51 % for modified PWM of harmonic injection n = 7 with GA optimization ma= 0.8 (A=0.0936 and ø = 0 rad) and up to 0.08 or decrease 12,30 % for modified PWM of harmonic injection n = 22 with GA optimization ma = 0.4 (A=0.1221 and ø = 0 rad).

Improving the Dimming Performance of Low-Power Single-Stage AC–DC HBLED Drivers

The design of efficient single-stage high-brightness light-emitting diodes (HBLEDs) ac–dc drivers with power factor correction (PFC) in low-power applications is addressed in this paper. The PFC is achieved by using a switching converter with both step-up and step-down voltage capability. It is well known that a good tracking of the input reference current close to the zero crossing is challenging, in particular when the LED output current is low, hence jeopardizing the power quality at low power levels. A solution is proposed to improve the power quality in ac–dc LED drivers under inner current loop based on a variable hysteresis modulation scheme. An adaptive hysteresis window modulated by the input voltage and the output LED current reference is used. The double modulation strategy helps to avoid the distortion near the zero crossings of the input current and to improve the dimming performance of the HBLEDs. This results in a low value of total harmonic distortion (THD) under low current/power conditions and therefore in a very good dimming performance in single-stage ac–dc HBLEDs drivers with PFC. The operation principle of the proposed technique is presented and numerical simulations are shown to demonstrate its functionality. A laboratory prototype is designed and tested to verify its feasibility obtaining a significant improvement in terms of power quality. Under universal input voltage operation, good efficiency and low THD can be achieved even for low power levels.

A simple input current wave-shaping technique for three-phase diode and SCR converters

ABSTRACTThree-phase converters using diode or silicon-controlled rectifier (SCR) are widely employed to convert the commercial AC supply to DC. Such converters inject harmonics into the power supply system and thereby distort supply system voltage waveform. A simple input current wave-shape improvement technique using a shunt-connected harmonic current compensator is presented in this work, intended to reduce the total harmonic distortion (THD) of input current of three-phase diode and SCR phase-controlled rectifiers operating with inductive loads, by matching them to the specific converter as a combined package. The compensator proposed here comprises of a three-limb voltage source converter using insulated-gate bipolar transistor, working on instantaneous current and voltage measurements of the compensator only and not of the load. The technique uses a simple feedforward control for AC source current harmonic compensation of rectifiers without monitoring the AC line currents, i.e. use of online computation. The proposed system is simulated and tested on a laboratory prototype. The measured input current THD values without additional line filters are found to be below 8.3%, which is within acceptable limits, proving that the new technique is capable of compensating predetermined current harmonics of diode or SCRs.

Fuzzy Logic Controller for Three Phase PWM AC-DC Converter

This paper discusses control strategy for the voltage regulation of a three phase pulse width modulation (PWM) AC-DC converter. A fuzzy logic controller (FLC) is employed in the outer voltage loop. Fuzzy logic controllers are preferred over the conventional proportional integral (PI) controllers because they are based on linguistic description and do not require a prior mathematical model of the system. The objective of the presented control system is to regulate the output DC voltage during both transient and steady state period. Also the line currents drawn from the grid should be sinusoidal and in phase with respective phase voltages to achieve a low total harmonic distortion (THD) and unity power factor. PI and FLC based control systems are implemented for three phase PWM AC-DC converter in MATLAB/Simulink and dynamic performance of the system is tested. The results demonstrate that compared to the conventional PI, the FLC based system is more robust and has a much better dynamic response. The low value of THD and sinusoidal current response ensures the system avoids polluting the utility grid.

Improved Damper Cage Design for Salient-Pole Synchronous Generators

The benefits of implementing a damper winding in salient-pole synchronous generators are widely known and well consolidated. It is also well known that such a winding incurs extra losses in the machine due to a number of reasons. In order to improve the overall efficiency and performance of classical salient-pole, wound field synchronous generators that employ the traditional damper cage, an improved amortisseur winding topology that reduces the inherent loss is proposed and investigated in this paper. This is essential in order to meet modern power quality requirements and to improve the overall performance of such “classical” machines. The new topology addresses the requirements for lower loss components without compromising the acceptable values of the output voltage total harmonic distortion and achieves this by having a modulated damper bar pitch. As vessel for studying the proposed concept, a 4-MVA salient-pole synchronous generator is considered. A finite element model of this machine is first built and then validated against experimental results. The validated model is then used to investigate the proposed concept with an optimal solution being achieved via the implementation of a genetic algorithm optimization tool. Finally, the performance of the optimized machine is compared to the original design both at a steady state and transient operating conditions.

Artificial bee colony algorithm for inverter complex wave reduction under line-load variations

This paper describes the minimization of total harmonics in a single-phase sine wave voltage source inverter using a proportional–integral (PI) controller by estimating the optimized values of PI constants using an artificial bee colony (ABC) algorithm under line-load variations. The single-phase inverter is a non-linear load using power electronic components causing distortions in the load voltage and current wave patterns from the sinusoidal waveforms due to harmonics. A state variable analysis for the single-input–single-output (SISO) model of an inverter was developed by considering the switching sequence of a voltage source full bridge sine wave inverter. The ABC algorithm calculates the optimized values of the constants for the PI controller, thereby tuning the controller for reducing the total harmonics of an inverter. The MATLAB/Simulink tool and an experimental set-up were implemented, and their total harmonic distortion (THD) values were estimated. The outcomes of the proposed ABC scheme were compared with the previous results such as the PI algorithm, fuzzy logic controller, neuro-fuzzy controller, particle swarm optimization (PSO) and the bat algorithm. A practical example of the ABC algorithm is considered in the present harmonic reduction problem. From the simulation and experimental results using the ABC algorithm, it was observed that its harmonics levels were reduced considerably compared with IEEE and IEC standards.

A Novel Power Factor Correction System Based on Sliding Mode Fuzzy Control

In this study, a novel Power Factor Correction System based on Sliding Mode Fuzzy Control is presented. This structure is used as an AC/DC/AC drive system for asynchronous machine. Non-sinusoidal source current of the system is improved to a sinusoidal waveform by the novel Power Factor Correction System controlled by Sliding Mode Fuzzy Controller. Sliding mode control technique (variable structure control) is preferred because of its robustness. Additionally, fuzzy control algorithm is adapted to Sliding Mode Control for eliminating or reducing chattering problem. A DC–DC boost converter is used to provide DC-link voltage to the inverter Three-phase voltages for Space Vector Pulse Width Modulation technique are represented by a voltage space vector in α-β space using the Clarke transformation for two-level voltage source inverter. The harmonic performance of the AC/DC/AC drive system, source side and load side current waveforms, and total harmonic distortion (THD) values are given in figures. Experimental results show the significant improvement in source current with eliminated harmonics and increased power factor from 0.63 to 0.998 value.

A Kalman Filter based Predictive Direct Power Control Scheme to Mitigate Source Voltage Distortions in PWM Rectifiers

In this paper, a predictive direct power control (DPC) method based on a Kalman filter is presented for three-phase pulse-width modulation (PWM) rectifiers to improve the performance of rectifiers with source voltages that are distorted with harmonic components. This method can eliminate the most significant harmonic components of the source voltage using a Kalman filter algorithm. In the process of predicting the future real and reactive power to select an optimal voltage vector in the predictive DPC, the proposed method utilizes source voltages filtered by a Kalman filter, which can mitigate the adverse effects of distorted source voltages on control performance. As a result, the quality of the source currents synthesized using the PWM rectifier is improved, and the total harmonic distortion (THD) values are reduced, even under distorted source voltages.

Significant insights into the operation of DC-link voltage control of a shunt active power filter using different control algorithms: a comparative study

A comparative study between a conventional DC-link voltage control algorithm (CDVCA) and a self-charging DC-link voltage control algorithm (SDVCA) is presented. It focuses on the principle operation of both algorithms and their impacts on the performance of a shunt active power filter (SAPF) operation. All analyses are based on the step response of DC-link voltages under different start-up times of the SAPF and different initial DC-link voltage values. Other considered parameters are the ripple factor (RP) of DC-link voltages, estimated and measured DC-link charging currents, and total harmonic distortion (THD) value of supply currents. Thus, this study provides new insights into the operation of DC-link voltage control using different control algorithms. According to the simulation results, the SAPF using the SDVCA has shown better performance than using the CDVCA. By using the SDVCA, the charging process of a DC-link capacitor starts almost instantaneously. Additionally, the overshoot, settling time, and RF of DC-link voltages are reduced. Other than that, THD values of supply currents are improved, by generating low ripple of estimated DC-link charging currents. Experimental validation of the SAPF using the SDVCA is also presented.

Exploration of Modulation Index in Multi-level Inverter using Particle Swarm Optimization Algorithm

This research paper describes the Particle Swarm Optimization algorithm real with Selective Harmonic Elimination-Pulse Width Modulation (SHEPWM) method for harmonic minimization of Cascaded H-Bridge Multi-Level Inverter. In SHEPWM method- PSO algorithm is capable of determining the required switching angles to eliminate desired value of harmonics. The value of harmonics may reach up to the 11th order from the inverter output voltage waveform while keeping the magnitude of the funda- mental harmonics at a certain value. Hence, the proposed method does capable of eliminating a great number of specific harmonics and the output voltage results in a minimum Total Harmonic Distortion value. The simulation results shows that the PSO algorithm successfully attains the global solution faster than other algorithms.

Improvement of Power Quality in Distribution System by Residential PV Systems

SUMMARYIn recent years, the deterioration in the power quality of a distribution system such as the aggravation of voltage imbalance and current imbalance or the increase of harmonics has been apprehended. It is thought to be causally related to the diversification of load by progress of power electronics technology and the increase of the number of interconnection of distributed generators for home use with the reduction of the effect on the environment. The purpose of this study is development of power conditioner systems (PCSs) with a function of improvement of power quality in the distribution system. In this paper, the authors propose a control method of restraint of harmonics and improvement of voltage imbalance in the distribution system utilizing the PCSs of photovoltaic systems. Moreover, it includes a determination method of the interconnection power factor and the optimal gain of filtering operation of PCSs so as to minimize the voltage imbalance factor and so as to minimize the maximum value of voltage total harmonic distortion in the distribution system by real‐time feedback control with measured data from the information technology switches of distribution line. The numerical calculation is carried out in order to verify the validity of the proposal method.