Total Harmonic Distortion Value Research Articles

A novel suppression method for input current distortion of the Vienna rectifier under unbalanced grid conditions

The Vienna rectifier is an excellent Power Factor Correction (PFC) AC–DC converter which has low Total Harmonic Distortion (THD) of input current, resistance to high-voltage, and high efficiency. Based on the structural characteristics of Vienna rectifier under the unbalanced grid conditions, considering the influence of grid voltage negative sequence component, the reference modulation wave of Vienna rectifier will lead or lag the input current, and the input current will be distorted which affects the power quality of Vienna rectifier. In this paper, a novel modulation waves clamping method by modifying the current command of the rectifier is proposed to eliminate the input current distortion under unbalanced grid conditions. By analyzing the distortion mechanism of the input current for a Vienna rectifier in unbalanced grid, the drawback of the conventional modulation waves clamping method for suppressing the input current distortion is illustrated, which shows that the method is ineffective in certain non-ideal grid conditions. Moreover, the proposed method modifies the current command, which realizes adjusting the clamping interval for modulation waves. So signs of the reference modulation wave and the input current are avoided to be inconsistent, and the input current distortion is suppressed. Besides, the quality of the input current is improved effectively. Finally, experimental results show that the proposed method can suppress the input current distortion obviously under the unbalanced grid conditions. Compared with conventional modulation wave clamping method, the THD value of the input current for a Vienna rectifier is reduced effectively (below 2%) with the proposed method.

Analysis of Output Signal Distortion of Galvanic Isolation Circuits for Monitoring the Mains Voltage Waveform.

Different methods for galvanically isolated monitoring of the mains voltage waveform were evaluated. The aim was to determine the level of distortion of the output signal relative to the input signal and the suitability of each method for calculating active power values. Six fixtures were tested: two voltage transformers, an electronic circuit with a current transformer, a standalone current transformer, a simple circuit with optocouplers, and a circuit with an A/D-D/A converter with capacitive coupling. The input and output waveforms were mathematically analyzed by three methods: (1) calculating the spectral components of waveforms and the relative changes in their THD (total harmonic distortion) values, (2) determining the similarity of waveforms according to the size of the area bounded by the input and output waveform curves, and (3) determining the accuracy of the active power calculation based on the output waveform. The time difference in the zero crossing of the input and output signals was measured, and further calculations for the second and third method were performed on the zero-crossing time shift-corrected waveforms. Other aspects of selecting the appropriate type of monitoring element, such as power consumption or overall circuit complexity, were also evaluated.

Research and Development of Adjustable Discontinuous Pulse Width Modulation Method for Three-Phase Voltage Source Inverter

Continuous pulse width modulation (CPWM) and discontinuous pulse width modulation (DPWM) strategies are used to control voltage source inverter operation. CPWM strategies allow for the reduction of total harmonic distortion values, while DPWM strategies provide a more effective reduction in inverter switching losses. The paper is devoted to the problem of improving the three-phase voltage source inverter efficiency by a controlled transition from CPWM to DPWM. The article proposes an adjustable discontinuous pulse width modulation (ADPWM) method, which means a transition from space vector PWM (refers to CPWM strategies) to DPWM in all inverter phases when the switches’ temperatures exceed the allowable value in at least one of the inverter phases. The method flowchart is presented and an algorithm for modifying the envelope curve within one sector is given. In order to test the ADPWM method a Simulink-model of a three-phase voltage source inverter and its control system were developed. A study of the proposed ADPWM method’s efficiency in comparison with CPWM, PCDPWM and NCDPWM methods was carried out using a Simulink-model. It was established that the proposed ADPWM method provides dynamic losses reduction in the inverter switches by 2.86 times compared to CPWM and by 1.89 times compared to PCDPWM and NCDPWM methods. Power supply systems for medium and high-power AC motors provide a promising area for application of the proposed ADPWM method.

Electronically and Independently Controllable Quadrature Sinusoidal Oscillator with Low Output Impedances

This work presents the quadrature sinusoidal oscillator using two Voltage Differencing-Differential Input Buffered Amplifiers (VD-DIBAs), two resistors, and two capacitors. The VD-DIBA is an electronically controllable active building block with high input and low output impedances that can connect to other circuits directly without the buffers. With these distinguished features, the VD-DIBA is employed in this design. The proposed oscillator can produce two sine waves with a phase shift of 90 degrees. Over the entire tuning frequency range, the magnitude of the quadrature output voltages is constant. The proposed oscillator is independently adjustable in terms of frequency and oscillation condition. Moreover, the frequency of oscillation can be electronically and linearly adjusted by the bias currents. The condition of oscillation is adjustable by resistors, R_1 and R_2. The performances of the proposed quadrature oscillator are tested through the PSpice simulation and the experiment. In the simulation, the VD-DIBA is built from the 0.18um Taiwan Semiconductor Manufacturing Company (TSMC) CMOS process with +-0.9V supply voltages. In the experiment, the VD-DIBA is implemented using the commercial ICs, LM13700, and AD830 with +-5V supply voltages. The simulated Total Harmonic Distortion (THD) values of the output voltages, V_o1 and V_o2 at f_0 = 1.03MHz are 1.63% and 1.81%, respectively. The experimental THD values of the output voltages, V_o1 and V_o2 at f_0 = 536.6kHz, are 1.43% and 1.00%, respectively.

Improved Design of a Six-Phase Squirrel Cage Induction Motor With Pseudo-Concentrated Windings

Pseudoconcentrated winding seems to be a promising solution for the six-phase induction motors (6PIMs) because it exposes advantages of concentrated windings (CWs) over the distributed windings (DWs). In addition, this winding has an air gap flux density with higher amplitude of the fundamental frequency and lower total harmonic distortion value compared to the conventional CWs, which results in considerably higher performance. In this article, a design algorithm and an analytical model are developed for a 6PIM to cope with pseudoconcentrated winding. Then, a sensitivity analysis is performed to enhance motor performance. The designed motor with pseudoconcentrated winding shows superior performance compared to the baseline motor with the DWs. The designed motor is manufactured to verify the accuracy of the design procedure, performance calculation, and finite element simulation results.

The development a fully-balanced current-tunable first-order low-pass filter with Caprio technique

This paper presents the development and design of a fully-balanced current-tunable first-order low-pass filter with Caprio technique, which could include the design and implementation of a first-order low-pass filter circuits. The filter consists of six bipolar junction transistor (BJT) and a single capacitor. The filter construction uses a bipolar junction transistor (BJT) as the main device and a single capacitor. A fully-balanced current-tunable first-order low-pass filter with Caprio technique developed. The architecture of the circuit is quite simple and proportional, symmetrical with signs of difference. Circuits developed into integrated circuits act like basic circuits for frequency filter circuits, current modes with Caprio techniques, obtained by improving the first-order low-pass filter for signal differences with incoming impedances. Adjusting the parameters of the circuit with the caprio technique achieves the optimal parameter value for correcting the total harmonic distortion value.
 The results of testing the operation of the circuit, a fully-balanced current-tunable first-order low-pass filter with Caprio technique developed and designed using the PSpice program. The simulation results showed good results in line with predicted theoretical analysis. The sensitivity of the device to the center frequency (ω0) response is low and independent of variables, the angular frequency is linear with wide current adjustment throughout the sweeping range of a wide frequency range, with a wide range of over tree orders of magnitude. Therefore, fully-balanced current-tunable first-order low-pass filter developed is very suitable to apply various applications regarding low frequency signal filtration, for example in biomedical systems, for example.

Development and validation of enhanced fuzzy logic controller and boost converter topologies for a single phase grid system

Introduction. Solar photovoltaic system is one of the most essential and demanding renewable energy source in the current days, due to the benefits of high efficiency, reduced cost, no pollution, and environment friendly characteristics. Here, the maximum power point tracking controller has been implemented for obtaining an extreme power from the photovoltaic array. For this purpose, there are different controller and converter strategies have been deployed in the conventional works. It includes perturb and observation, incremental conductance, fuzzy logic systems, and hill climbing, and these techniques intend to extract the high amount of power from the solar systems under different climatic conditions. Still, it limits with the issues like increased design complexity, high cost consumption, high harmonics, and increased time consumption. The goal of this work is to deploy an improved controlling and converter topologies to regulate the output voltage and power fed to the single phase grid systems. The novelty of the work aims to develop an enhanced fuzzy logic controller based maximum power point tracking mechanism with the boost DC-DC converter topology for a single phase grid tied photovoltaic systems. Practical value. Also, the higher order harmonics suppression and unbalanced current elimination are handled by the use of LCL filtering technique, which efficiently reduces the harmonics in the output of inverter voltage and current. Moreover, it helps to obtain the reduced total harmonics distortion value with improved accuracy and efficiency. Results. There are different performance indicators have been evaluated for validating the proposed enhanced fuzzy logic controller–maximum power point tracking controlling technique. Moreover, the obtained results are compared with some of the conventional controlling algorithms for proving the betterment of the proposed work.

Integrated Damper Cage for THD Improvements of Variable Speed Salient-Pole Synchronous Generators for the More Electric Aircraft

Wound field synchronous generators (WFSGs) have been implemented as aircraft main ac power generation for decades. The trend of moving toward more electric aircraft (MEA) made dc and variable-frequency ac buses favorable for the next-generation power systems in aircraft, as opposed to constant frequency ac grid systems. The minimization of the generators’ output voltage total harmonic distortion (THD) is an ever-more critical objective, especially for variable-frequency power systems where this target has to be met within the whole range of operating speeds. In conventional, constant speed, and WFSGs, a number of consolidated techniques are implemented to meet this requirement. In variable-speed SGs intended for the MEA, these techniques are no longer fully effective and new methodologies are thus necessary. This article replaces the conventional squirrel-type damper cage with a new integrated damper cage (IDC) located at the interpole regions. The proposed IDC, while acting as a mechanical structure to retain the field windings at high operating speeds, also achieves very low-voltage THD values at different speeds, thus complying with the power quality requirement. A 250-kVA prototype is designed, analyzed, built, and tested to prove the proposed concepts and methodologies.

Expert knowledge based proportional resonant controller for three phase inverter under abnormal grid conditions

ABSTRACT Integration of photovoltaic (PV) power to the grid is achieved using three-phase inverters with high-quality current waveforms. The new grid codes impose a limit on the total harmonic distortion (THD) value of the inverter’s current waveforms. Due to simple structure and ease of design, proportional integral (PI) controllers are the most widely adopted methods to control three-phase grid-connected inverters; however under abnormal grid conditions, PI controllers may suffer from instability problems. To address the aforementioned problem, this article proposes an expert knowledge-based proportional resonant (PR) control for the integration of PV power to the grid under abnormal grid conditions. The proposed control method adjusts the control parameters based on rules generated from expert knowledge. Initially, parameters of the proposed control methods are optimized using particle swarm optimization (PSO) method. The proposed control is tested with a 100 kW grid-tied three-phase inverter unit under normal and abnormal grid conditions and its performance are compared with PI and fixed gain PR control methods. Moreover, the proposed control is tested experimentally with a scaled down 300 W grid-tied inverter lab prototype module. From the simulation and experimental results, it is verified that the proposed adaptive PR control technique is capable of providing low THD in the injected current under abnormal grid conditions compared with fixed gained PR controllers.

Experimental Design and Analysis of Adaptive LED Illumination System

Light emitting diode (LED) luminaires are widely used in street, road, and tunnel illumination. It is necessary to detect their negative effects on power grid, especially in terms of power quality distortions. In addition, because of the limited energy sources, they have to be operated in most efficient way. This paper proposed an adaptive illumination system that can be used in highway tunnels. In this context, an experimental system that consist of LED luminaires with various power values that are possible to be used in tunnel illumination was implemented. Scenarios have been created for the designed system in accordance with possible tunnel illumination scheme. Siemens S7–1200 PLC was used to control these scenarios. FFT analysis of the measurements obtained with adaptive illumination scenarios was performed and power quality distortions were determined for different harmonic levels. Similar analysis was repeated for the non-adaptive system, and a detailed comparison was proposed. In addition, both systems were compared in terms of energy consumption. Operational characteristics of adaptive illumination systems were discussed by using the obtained data. Results show that total harmonic distortion (THD) for all luminaires are active situation is quite lower than adaptive illumination scenarios, where the values of current THD are 149.7 %, 119.9 %, and 85.8 % that scenario 1, scenario 2, and all luminaires are in active situation, respectively. On the other hand, as advantage, a power saving of 73.4 % and 60.3 % can be achieved compared to different adaptive illumination scenarios according to all luminaires are active.

Comparative Study of Multiphase 5-Level Cascaded H-Bridge Multilevel Inverter System

In terms of cost and structural design, the cascaded H-bridge multilevel inverter (CHBMLI) has a significant advantage over diode clamped and capacitor clamped multilevel inverters. The total harmonic distortion (THD) of a 5-level CHBMLI system for three different phases (single-phase, three-phase, and six-phase system) is studied and compared in this work. As switching angles play a role in lowering THD, the switching angles for a 5-level CHBMLI are evaluated using four specific switching angle methods in the initial section of this paper. In the simulation of single-phase system, these angles are being utilized. The angles with the lowest THD value are chosen for three-phase and six-phase system simulation. Based on the findings, the higher phase of 5-level CHBMLI is more efficient in decreasing harmonics.

ELECTROMAGNETIC COMPATIBLE CURRENT SOURCES WITH RELAY CONTROL

The development of industry leads to an increase in nonlinear loads, which are generators of higher harmonics in the network. The quality indicators of voltage and current consumed from the network are established by international standards for the quality of electricity. The simplest method of filtering harmonics is passive filters, lack of low quality harmonic compensation. The use of active filters improves the quality of the current. But active filters have a complex control system. The use of active rectifiers as part of semiconductor power supplies solves the problem of generating higher harmonics in the network and provides a power factor equal to 1.
 Six variants of three-phase and single-phase power supplies have been developed. They operate as a current source. All circuits consist of two parts: an active rectifier and a DC-DC converter. The scope of use of such sources is different: a direct current electric drive, an electric power system of wind turbines, an electric system of aircraft. The control system of the relay converters provides the formation of current and the maximum speed in the processing of disturbances. 
 Oscillograms of the current sources are obtained by digital modeling. They confirm the efficiency of the proposed sources, the electromagnetic compatibility of the power sources with the mains and the value of the power factor close to unity. Current sources are invarant to the action of disturbances: changes in load resistance, mains voltage. The study of electromagnetic processes made it possible to obtain analytical expressions for the maximum and minimum frequency of the relay mode, the capacitance of the capacitors and the operating conditions of the sources. 
 The developed program allows you to get the parameters for choosing the power elements of the circuit: inductance, capacitance, switching frequency of transistors. 
 The quality of the consumed current is analyzed by calculating the total harmonic distortion (THD). For all considered sources, the THD value is less than 5%, which meets the quality standards for the consumed current.

Plug-in disturbance observer assisted DC link voltage control of grid-connected converters to improve transient performance without deteriorating grid current quality

Trade-off between DC link voltage dynamics and AC-side current quality in grid-interfacing power converters limits the attainable DC link voltage loop bandwidth for a given desired value of grid-side current total harmonic distortion (THD). It was recently shown that adding a notch filter in series with the typically employed DC link voltage controller of PI or type-II structure releases the above trade-off, yet requires full controller re-design. The paper proposes to replace the notch filter by a plug-in disturbance observer, allowing to increase attainable DC link voltage loop bandwidth for given grid-side current THD without any modification of the existing DC link voltage controller by utilizing a special frequency-selective filter. Simulations and experimental results validate the proposed design methodology.

The analysis of three level inverter circuit with regard to current harmonic distortion by using ANFIS

The inverters are frequently used in power electronics applications in the industrial area. Research on multi-level inverter circuit designs in power systems interfaces has intensified in recent years. The design type and quality of the inverter circuit topology is very important for the output voltage to be closer to the sinusoidal waveform. In addition, artificial intelligence techniques for the control algorithms of the power switches of the inverter circuit provide useful information in terms of monitoring the estimated the voltage conditions of the inverter output parameters. In this work, an Adaptive-Network Based Fuzzy Inference Systems (ANFIS) model is proposed to estimate the Total Harmonic Distortion (THD) value of the output current of a three-phase three-level inverter circuit. By changing the switching frequency in the control circuit of the inverter, a data set for the THD values of the inverter current is obtained by Fast Fourier Transform (FFT) analysis in MATLAB. This data set is used in a training and testing phase of ANFIS artificial intelligence algorithm, and the THD value of the current is estimated. At the end of the estimation, the mean absolute error (MAE) values for training and testing are obtained as 0.1894% and 0.4009%, respectively, thereby, an ANFIS estimation example for parametric data set analysis in a power electronics circuit run with Matlab-Simulink software, and a parametric simulation study is presented to the literature for power electronics circuit designers.

Active Harmonic Filtering for Improving Power Quality of an Electrical Network

The increase use of polluting equipment, especially in the field of power electronics, has caused appearance of harmonics and deterioration in the supplied current wave quality. For this reason, several harmonic pollution control methods have been developed, and the use of the active filtering presents the most efficient and appropriate solution. This work concerns improving energy quality of an electrical network by using an active parallel filter. To achieve this objective, three essential steps were pursued: identification of the harmonic currents, insertion and control of an active parallel filter, and checking effectiveness of the adopted filtering strategy by comparing the total harmonic distortion (THD) values before and after filtering. The various obtained results prove capacity of the inserted active filter to decontaminate harmonic pollution and consequently improve the energy quality.

A Real-Time Fault-Tolerant Control Approach to Ensure the Resiliency of a Self-Healing Multilevel Converter

Ensuring service continuity in safety critical applications is crucial. In some of these applications, multilevel converters play a vital role. In this regard, this research work presents a self-healing fault-tolerant control approach to ensure the resiliency of a neutral-point clamped converter when a semiconductor component encounters an open circuit fault. The defective semiconductor can be a power switch or a clamping diode. By applying the proposed real-time fault-tolerance control, the rated output voltage and output current are restored during post-fault operation. Furthermore, the total harmonic distortion value of the output voltage during application of the real time self-healing control does not increase when compared with that during healthy operation. Since the realization of the proposed control strategy does not require any bidirectional switch, a fast transition between the healthy and fault-tolerant operation is accomplished. Moreover, the proposed structure can ensure service continuity in case of a fault event in the anti-parallel diodes, something which has been overlooked in previously conducted research works.

A Novel Single-Phase Shunt Active Power Filter with a Cost Function Based Model Predictive Current Control Technique

For a single-phase Shunt Active Power Filter (SAPF) with a two-step prediction, this research presents a modified current control based on a Model Predictive Current Control (MPCC) technique. An H-bridge inverter, a DC link capacitor, and a filter inductor comprise the single-phase SAPF topology. The SAPF reference current is computed using the DC-link capacitor voltage regulation-based PI control technique. The weighting factor-based model predictive current controller is used to track the current commands. The essential dynamic index for evaluating waveform quality is the Total Harmonic Distortion (THD) of a source current and switching frequency of power switches. The conventional methods the THD and switching frequency are not considered as an objective function, so that a weighting factor-based MPCC technique is used to obtain a good compromise between the THD of the source current and switching frequency of power switches. Through MATLAB simulation and experimentation with the Cyclone-IV EP4CE30F484 FPGA board, the usefulness of the proposed control technique is proven. As compared with hysteresis, predictive PWM, and conventional MPCC control methods, the cost function-based MPCC algorithm provides a lower switching frequency (13.4 kHz) with an optimal source current THD value.

Binary-phase service battery energy storage system strategy for peak demand shaving and enhanced power quality

Owing to nonlinear and large consumer loads, power grid system operators encounter major challenges in matching the generated power supply to consumer power demand to smooth out the high-peak load demands and mitigate the voltage and current disturbances within the electrical grid. A battery energy storage system (BESS) is employed as a two-phase control technique to minimize the peak load demand of the system and enhance the power quality within the electrical grid system. The phase I control strategy presents a robust artificial neural network control, which is implemented considering the BESS state-of-charge (SoC) and operation time-of-day (ToD) of the customers’ loads to identify load peaks at each period of the day to effectively reduce the high-load demand. Moreover, in the phase II control strategy, a customized BESS-hybrid series-shunt active power filter (B-HSSAF) is presented to effectively mitigate the grid disturbances, which results in an enhanced grid system as suggested by the simulation results. The total harmonic distortion values after compensation using the B-HSSAF satisfy IEEE standard 519, and the power grid is enhanced. Furthermore, qualitative discussions of the optimal location of the BESS and dynamic thermal rating integration which are limitations of this paper are concisely presented with recommended further studies that can be taken into consideration.

A Hybrid Approach for Optimal Sizing of Inverter-Based Distributed Generation Unit in Presence of Harmonic Distortion Limit

This paper presents a hybrid approach to calculate the optimal size of inverter-based distributed generation unit located at any given bus of a radial distribution network to minimize the active power loss in the network in presence of limit imposed on the maximum allowable value of total harmonic distortion in bus voltages. The suggested approach combines efficient iterative computations with a rule base developed in the present work, and requires much less computation compared to the evolutionary population based methods reported so far, to reach the desired solution. In support of this claim, the proposed methodology was tested on two bench-mark distribution test systems, and the test results were compared and validated with those obtained using Particle Swarm Optimization technique. PSO has been chosen for comparison as it is one of the most widely used among the evolutionary population based methods due to its simple approach, ease of implementation, and also because of its superiority in terms of precision, robustness and speed of convergence. From the comparative results it has been established that the proposed method can provide solution for the problem undertaken in this work with significantly less computation than is required by the evolutionary computation based methods.

Studi Analisis Perbandingan Pwm Carrier Untuk Multilevel Inverter Tiga Fasa Lima Belas Level Dengan Sumber Input Simetris Terpisah

Inverters are used to convert direct current or DC (Direct Current) sources into alternating current sources or AC (Alternating Current). A method is needed to make the output waveform close to a sinusoidal waveform. The Multi Level Inverter (MLI) method has a large number of levels and is closer to a sinusoidal wave. The three-phase MLI design with a separate symmetrical input source in this study is able to produce a three-phase output wave, where the resulting Total Harmonic Distortion (THD) value is smaller, namely 5.65% when using the Modified PWM method where the carrier signal has no frequency