Total Harmonic Distortion

The simulated two levels PWM driver circuit is designed successfully and implemented in hardware project. The sinusoidal wave shape has been achieved (no load) with minimum total harmonic distortion and ripple. Transformer impedance matching and feedback control system design is necessary for the PWM driver to be effectively implemented in inverter. Total harmonic distortion (THD) in AC voltage would be mitigated much more when high frequency (more than 8 kHz) carrier signal would be used in the implemented circuit.

The function of a single tuned filter is to filter out specific frequency by creating a low-impedance path to ground. The dominant harmonics currents will flow out of the load resulting in a lower total harmonic distortion (THD). A single tuned filter can be tuned on a specific frequency by making the inductive and capacitive cancel each other out. The most dominant frequency is usually selected to obtain better harmonic mitigation from the single tuned filter. The double tuned filter design is an improvement from the single tuned filter design. It is designed to improve the performance of the single tuned filter [7].

Abstract- In general the Induction Motor is known to be a constant speed motor. In most of the industries the induction motor is mainly used for Drive Systems. But due to the advances in computer technology the speed of the induction motor can be controlled under certain conditions. There are many ways to control the speed of the Induction Motor for variable speed applications. The basic method is 2-level inverter controlled by microcontroller using space vector modulation. In this method the output of the inverter may not be exactly sinusoidal and hence at the star point of the Induction Motor winding, causing a Voltage Harmonic Distortion in the output of the inverter. To minimize the voltage harmonic distortion a multilevel inverter can be used. In addition, the harmonic frequencies will not produce usable torque but causes heating the Induction motor windings, which are harmful to the insulation. In this paper two level and three level inverter fed induction motor driven at various frequencies are reported. Simulation, experimentation and the measurement of voltage total harmonic distortion have also been reported. In the experiment the Arduino microcontroller, Line Impedance Stabilization Network, opto- isolator, Hall Effect sensor, H-bridge inverter and other necessary electronic circuits are used. The measurements are recorded using Agilent make Mixed signal Oscilloscope. The Fast Fourier transform has been carried out for the experimental result, using signal analysis software. Simulation has been implemented using the MATLAB/Simulink. The results of simulation and experimentation are compared and tabulated.

In this paper the performance of a proposed three level cascaded MLI-DSTATCOM is analyzed using Synchronous Reference Frame based control scheme with neural network controller for %THD reduction in distribution network. The operation of proposed system is analyzed using MATLAB/SIMULINK software. It can be concluded that Three level Cascaded Multilevel inverter Distribution Static Compensator using Synchronous Reference Frame Theory control scheme with neural network controller effectively improves the power quality in distribution networks. Using neural network, it improves the trustworthiness of the reduction in Total Harmonic Distortion in Distribution Networks. The simulation results show that current perturbations caused by non-linear load can be compensated effectively by the proposed control strategy and thus the prediction error obtained by Neural Network model is very plausible. So the Neural Network model produces reliable estimates of current THD. The results have also pointed out that Neural Network can implement many other data prediction efforts easily and successfully, the ANN controllers are very effective and efficient compared to the PI and PID controllers, because the steady state error in case of ANN control is less and the stabilization of the system is better in it. In the ANN methodology the time taken for computation is since there is no mathematical model .

A table is created in Double Precision Floating Point. The following commands make a 256 point sine wave and measure its total harmonic distor- tion when sampled first on the points and then by jumping with a delta of 2.5 points per step using linear interpolation. For frequency-based appli- cations, spectral purity can be more important than absolute error in the table. The M-file is used for calculating total harmonic distortion (THD) for digital sine wave generation with or without inter- polation. This THD algorithm proceeds over an integral number of waves to achieve accurate re- sults[4]. The number of wave cycles used is A.

Here the mathematical model of a SVM based three phase inverter is formulated and simulations are done with MATLAB/Simulink. From the results it can be given that the total harmonic distortion can be reduced appreciably. This model can be applied to various motor applications and also to non-linear loads to get a less distortion results.

Multilevel inverters have been widely used in medium and high voltage applications. Different modulation techniques have been proposed to control the multilevel inverter. This paper presents a switching strategy for cascaded multilevel inverters, based on space vector modulation. The SVPWM can be applied practically in hybrid multilevel inverters with different voltage steps; it can be applied to most multilevel topologies. This paper proposes a new algorithm for hybrid multilevel inverters with unequal voltage steps under the space vector pulse width modulation (SVPWM). The proposed algorithm offers an intuitive method for minimizing the total harmonic distortion (THD) of the output voltage of the inverter and uses simple arithmetic for determining the sector and does not require lookup tables. The proposed techniques lead to a significant reduction in THD. Finally, the algorithm was implemented on a Digital Signal Processor (DSP) and the scheme is explained for a seven level inverter, and experimental results are presented for a seven level inverter.

Abstract:- When using nonlinear loads, affects the quality of supply power ,which leads to a number of issues like harmonics, voltage sag, voltage swell, flicker, voltage imbalance etc. These issues affect the performance and the lifetime of the utilities. In order to overcome issues arises due to nonlinear loads power filters were developed. This work proposed an active filter which is controlled by PI controller and Fuzzy logic controller to reduce the THD (total harmonic distortion). Here we compared the results of active filter results, without controller and with PI and Fuzzy controller. Results show that performance of fuzzy controller is better than PI controller.

Abstract— A neural network based space vector modulation (SVM) of voltage source inverter is proposed. The voltage source converter (VSC) is highly used in high voltage direct current (HVDC) transmission so that a detailed analysis and transmission of this system is carried out. In addition, a non-linear neural network controller is proposed to control the space vector pulse width modulation (SVPWM) to reduce the total harmonic distortion (THD) of the converter (inverter) output voltage. The inverter outputcurrent is analyzed with two switching frequency 1050Hz and1450Hz with and without proposed ANN controller. The results show a THD enhancement about 0.74 % for 1050Hz and 0.68 % for 1450Hz.

Abstract- The worldwide installation of solar photovoltaic (PV) system has proliferated in the last decades. This will inevitably introduce power quality issues to the grid as the solar PV penetration increases. The high switching frequency from the solar inverter has produced unwanted electrical signals that will eventually injected into the power grid. Thus, this paper aims to investigate the total harmonic distortion (THD) performance of the solar inverters under real operating conditions. More specifically, it focuses on the THD performance of the single-phase grid-tie inverters which are installed at Universiti Teknikal Malaysia Melaka (UTeM). The well-established K-Means clustering technique has been utilised to perform the characterization of THD current from the collected data. In addition, the correlation between the THD current with the solar irradiance and the inverter’s output power ratio were also presented and discussed. The findings of this study suggest that the THD current from a solar inverter is highly dependent on the solar irradiance of which the recorded THD current values can be as high as over 60% during the starting-up and shutting-down of the inverter. Furthermore, the THD current values can be broadly categorised into four different categories, depending on the level of solar irradiance.

In Power System applications one major problem in output is distortion. For mitigation of this different methodologies have been used. With advances in Solid-State Power Electronics Devices, various Pulse Width Modulation (PWM) techniques have been developed for Industrial applications. Shao-Liang An, Xiang-Dong Sun, Member, IEEE, Qi Zhang, Yan-Ru Zhong, and Bi-Ying Ren has been studied SVPWM Technique and this paper shows further study and talk about reduction of total harmonic distortion. PWM is a means of transmitting information in a series of pulses, where the data being transmitted is encoded in the width of the transmitted pulse. In the Space Vector Pulse Width Modulation technique, the duty cycles are computed rather than derived through comparison as in Sine Pulse Width Modulation. The SVPWM technique can improve the fundamental component by up to 27.39% than SPWM. This paper discusses the studies of Space Vector PWM technique (SVPWM). The simulation results show that the SVPWM technique has lower total harmonic distortion than the PWM technique.

Abstract---This paper deals with analysis of Total harmonic distortion (THD) for grid connected photovoltaic (PV) systems. In the utility grid, four different inverter topologies like Z-Source Inverter, Voltage Source Inverter, Current Source Inverter, and Multi-level Inverter are connected together and Total Harmonic Distortion (THD) analysis are obtained in MATLAB SIMULINK and simulation outputs are presented.

Adapter used common use power supply mostly didn’t affect distortion. Because theoretically, most of even harmonic component was eliminated. Distortion of power supply can be caused by non-linearities of semiconductors. And the total harmonic distortion of earphone was generated due to get out of linear range of diaphragm’s maximum oscillation range.

Abstract - This paper deals with reduction of total harmonic distortion in new Cascaded H-bridge multilevel inverter topology with artificial neural network technique. This topology consists of lower blocking voltage on switches and it requires less number of dc voltage sources, power switches which results in decrease the complexity and total cost of the inverter. Moreover, a new algorithm is used to determine the magnitude of dc voltage sources for generation of all voltage levels. Artificial Neural Network (ANN) is trained by the back-propagation algorithm of the Mean Square Error (MSE) between the output and the desired value. The performance and functional accuracy of the proposed topology using ANN technique in generating all voltage levels for 31-level inverter are simulated using MATLAB simulink.

This paper presents a genetic algorithm (GA) optimization technique to find the optimum switching angles of 11-level inverter with minimum number of dc sources and switches in comparison with the cascade multilevel inverter in order to minimize the total harmonic distortion (THD) of their output voltage waveform. Theoretical and simulation results for an 11-level converter show the efficiency of the proposed algorithm to determine the optimum angles in order to decrease the undesired harmonics and produce very high quality output voltage waveform.

It is important, therefore, in a simulation model to include the nonlinear core model to ensure that the transformer does not degrade the performance of the system as a whole. This paper concentrates on this aspect of the transformer design, with inves- tigations carried out into the tradeoffs of material characteristics and air gaps, the effect of core size and number of windings on performance, and comparisons between different winding configurations and core types. Previous work [26] describes the basic design procedure for DSL transformers, but relies on “rule of thumb” calculations and simplification of the THD figures. It is proposed in this paper to apply circuit simulation to more ac- curately predict the effect of nonlinear ferrite cores on the trans- former’s performance. The proposed model will have a similar parasitic model to that described previously, but will include an accurately characterized nonlinear core model. In this case, the original Jiles–Atherton [27]–[29] model has generally been used. The modifications to the Jiles–Atherton model that have been proposed previously by Wilson et al. [30]–[33] generally refer to heavily saturated cores, and in general the ADSL trans- formers operate at low signal levels implying minor – loops. D. Distortion Performance Criteria

Several application use cycloconverter circuit for example cement mill drives, ship propulsion, HVDC transmission systems and Aircraft or shipboard power supplies Mine winders [1],[2],[3]. When, number of poles in induction motor are changed, motor speed will change. However, these method is not technical [4]. So, Cycloconverter power electronic circuit involve in this field in changing supply frequency. It works to change the fixed input frequency into higher or lower than input frequency which depend on required application. However, there is huge harmonics in output of power converter. These harmonics effect on the power system network. Which cause distortion in voltage and current waveform [2],[8]. So, in this paper will be focused on harmonics and THD comparison between MOSFET, IGBT and GTO as power devices in single phase mid-point Cycloconverter power electronic circuits. In addition, which of these power devices will be more suitable in Cycloconverter circuit in step up and step dawn frequency.

On the other hand, Payne et al. [12] briefly compared the different types of fault diagnosis system in transverse flux motor that is presented in Table 1. Their results showed the monitoring devices which rely on the electromagnetic flux as a local variable had very high accuracy. Even though the content of this research refers to a transverse flux motor, which is not typical of industrial drives, this may also be considered as being representative of any kind of electrical machine, since the same potential measurement parameters are presented by other researches as likely to provide useful condition-indicating information for possible fault modes [9]. In this respect, some studies [9], [13]-[20], including this work, were aimed to transfer a part of the current signature analysis knowledge to techniques that monitor the signatures generated by the fault to the magnetic flux signals. Hence, as a recent trend, fault monitoring of rotating electrical machines using magnetic field measurements have been proposed as a common subject of investigation [17], [18]. In this paper, a fault indicator based on harmonic analysis of the magnetic flux linkage for the diagnosis of turn-to-turn winding fault in a salient-pole synchronous generator is presented. Also, probabilistic neural network (PNN) and discrete wavelet transform (DWT) are used in design of fault diagnosis system. PNN as the main part of this fault diagnosis system and DWT are combined effectively to construct the classifier. In this contribution, DWT is used only for de-noising, because by reducing the noise, better network training is done. The main feature of the proposed method is that it is capable of identifying the faulty coils under winding faults. Simple algorithm, low cost sensor and sensitivity are other features characterized by the proposed technique. In this method, the generator air gap flux linkage is measured via search coils sensor installed under the stator wedges inside the machine. This sensor is readily accessible on the market and its cost is very low.

shunt and series active power filters. The series part of the UPQC is known as Dynamic Voltage Restorer (DVR). It is used to maintain balanced, distortion free nominal voltage at the load. The shunt part of the UPQC is known as Distribution Static Compensator (DSTATCOM) and it is used to compensate load reactive power, harmonics and balance the load currents thereby making the source current balanced and distortion free with unity power factor [1-3].

Z-source inverter (ZSI) which is based on Z-source network can be used to buck and boost the output AC voltage, which is not possible using traditional voltage source[r]