Analytic Mode Decomposition and Windowed Three-Point Interpolated Chirp-Z Transform for Voltage Flicker Components Detection

A novel approach has been presented in this paper to calculate voltage flicker components precisely by using instantaneous voltage vectors. After the voltage waveform of a phase is recorded, the smart discrete Fourier transform can be used to obtain the system frequency and magnitude. Then, the other two phases are assumed perfectly sinusoidal to construct a virtual three-phase system. The instantaneous voltage vectors are calculated from the virtual three-phase voltages. Finally, the fast Fourier transform is used to obtain the voltage flicker components from instantaneous voltage vectors. The flicker components of the other two phases can be calculated by repeating the procedure. The flicker values of three phases are calculated individually and separately. The effects of jump-sampling, harmonics, power frequency shifting, and sampling rates are investigated. The calculation ability of this approach is compared with the traditional indirect demodulation method. Some given waveforms and field measured waveforms of arc furnace loads with voltage flicker disturbances are used to show the goodness of this approach. From the results, this approach could calculate flicker components accurately with short calculation time by using small size data. It also avoids the frequency leakage effect.

Chapter 38 - Power quality

Effective and accurate calculation methods are presented to obtain the voltage flicker components and the 10-Hz equivalent value. By using the indirect demodulation method, the RMS values of a voltage waveform are calculated cycle by cycle to obtain the envelopment. Then the fast Fourier transform (FFT) is used to get the flicker components. The other method uses the instantaneous voltage vectors. After the voltage waveform of a phase is recorded, the discrete Fourier transform can be used to get the system frequency and magnitude. Then the other two phases are assumed perfectly sinusoidal to construct a virtual three-phase system. The instantaneous voltage vectors are calculated from the virtual three-phase voltages. Finally, the FFT is used to obtain the voltage flicker components from instantaneous voltage vectors. Some given waveforms and field measured waveforms of arc furnace loads with voltage flicker disturbances are used to show the goodness of these approaches.

These days, the application of electronic power transformers (EPTs) is expanding in place of ordinary power transformers. These transformers can transmit power via three or four wire converters. Their dynamic performance is extremely important, due to their complex structure. In this paper, a new method is proposed for improving the dynamic performance of distribution electronic power transformers (DEPT) by using sliding mode control (SMC). Hence, to express the dynamic characteristics of a system, different factors such as the voltage unbalance, voltage sag, voltage harmonics and voltage flicker in the system primary side are considered. The four controlling aims of the improvement in dynamic performance include: 1) maintaining the input currents so that they are in sinusoidal form and in phase with the input voltages so they have a unity power factor, 2) keeping the dc-link voltage within the reference amount, 3) keeping the output voltages at a fixed amount and 4) keeping the output voltages in sinusoidal and symmetrical forms. Simulation results indicate the potential and capability of the proposed method in improving DEPT behavior.

In recent years, electronic power transformer (EPT), which is also called solid state transformer, has attracted great interest and has been used in place of the conventional power transformers. These transformers have many important functions as high unity power factor, low harmonic distortion, constant DC bus voltage, regulated output voltage and compensation capability. In this study, proposed EPT structure contains a three-phase pulse width modulation rectifier that converts 800 Vrms AC to 2000 V DC bus at input stage, a dual active bridge converter that provides 400 V DC bus with 5:1 high frequency transformer at isolation stage and a three-phase two level inverter that is used to obtain AC output at output stage. In order to enhance dynamic performance of EPT structure, neuro fuzzy controllers which have durable and nonlinear nature are used in input and isolation stages instead of PI controllers. The main aim of EPT structure with the proposed controller is to improve the stability of power system and to provide faster response against disturbances. Moreover, a number of simulation results are carried out to verify EPT structure designed in MATLAB/Simulink environment and to analyze compensation ability for voltage harmonics, voltage flicker and voltage sag/swell conditions.

The paper deals with the measurement of the influence of new technology household appliances on the power quality. A virtual instrument for power quality monitoring based on NI LabVIEW™ platform and simultaneous measurements of electrical voltages and currents, as well as powers, frequency, voltage variations, magnitude of rapid voltage changes, flicker severity, voltage unbalance and total harmonic distortion is described. The virtual instrument-power analyser enables measurement of power characteristics in non-sinusoidal conditions. Power measurements (P, Q and D) of household appliances are presented and discussed. The influence of the modern, domestic energy saving lighting and inverter air conditioners, as significant household consumers, on the power quality of the electrical energy is considered.

Power electronics and related power processing technologies constitute an "enabling infrastructure technology" with a significant potential impact on US industrial competitiveness. This is manifested through the increased energy efficiency of equipment and processes using electrical power, and through higher industrial productivity and higher product quality, which results from the ability to control precisely the electrical power for manufacturing operations. Sales of power electronics equipment exceed $60 billion each year, and affect another $1 trillion in hardware electronics sales. Improvements in the technology of such a dynamic market is an exciting endeavor. Industrial firms are under constant pressure to produce power electronics products that are more powerful dependable and durable, smaller in size, lighter in weight, and less costly to the consumer. Power electronics products, to date, are essentially custom-designed, with a long design cycle time. The equipment is designed and manufactured largely using nonstandard parts. Thus, manufacturing processes are labor-intensive, resulting in high cost and poor reliability. Consequently, the US is losing its manufacturing base to global competitors, especially in those regions where labor costs are significantly lower than those of the US. This paper discusses the limitations in power semiconductor devices, passive components, power electronics packaging, power electronics modules, motor drives, and new generation computer/telecommunication equipment. The technology advancements needed are then discussed.

As the boost of power electronics technology, the harmonic problem in the power system is becoming increasingly prominent. Fourier decomposition is performed on the load current in the power system, and components with a frequency that is an integer multiple of the fundamental wave are referred to as harmonic components. Harmonic control is essential to establish a safe and reliable power grid environment and provide high-quality and clean electricity to power users. The study focused on parallel active power filters, proposed a specific harmonic detection method on the grounds of synchronous harmonic rotating coordinate system, and developed a phase-locked loop design on the grounds of order generalized integrator. Meanwhile, a compensation current control method on the grounds of space vector pulse width modulation was introduced. The results showed that in the full compensation simulation experiment, the compensated A-phase grid side current waveform was significantly improved and presented a sinusoidal shape. After 0.05 s, the actual output compensation current closely followed the command current. Meanwhile, after compensation, the total harmonic distortion rate decreased from 26.58 to 3.06%. In specific harmonic compensation simulation experiments, when the sum of 5th, 7th, and 11th harmonic components was used as the command current for compensation, the distortion of the current waveform was improved after the load undergoes a sudden change. After compensation, the 5th, 7th, and 11th harmonic content significantly decreased, and the total harmonic distortion rate decreased to 4.08%. This indicated that the proposed phase-locked loop design and harmonic detection method for active power filters had high stability and effectiveness. The study’s primary contribution is to enhance the utilization efficiency of DC voltage and improve the dynamic response ability of current. Additionally, it offers a new method for reducing the impact of harmonics on the power grid and improving power quality. It provided an effective method reference for technological progress in related fields such as power electronics and control engineering.

Wide-bandgap (WBG) power semiconductor devices have good potential to replace Silicon-based devices for operating at higher temperatures. Silicon carbide (SiC) currently represents an established WBG candidate for developing power Schottky barrier diodes (SBD) used in power electronics that are required for the next generation power devices. Very few information is available about P-type 4H-SiC substrate being used for realization of SBD. Pre-production Technological computer aided design (TCAD) simulation of SBD, where p-doped epitaxial layer on p-type 4H-SiC substrate corresponds to experimental structures (currently in manufacturing process) could generate defects under the contact. P-type SiC SBD with some defects types is also examined for evaluating the influence on the forward current and reverse voltage blocking. Forward and reverse bias static characteristics are obtained for p-type 4H-SiC SBD at temperatures in the range of 300K to 600K. The currents are shown to have a large on resistance and tunneling component depending on the defects. The SBD device simulation shows that there is significant impact on the reverse current and voltage despite of the very thin defective layer. The reverse breakdown voltages of the diodes were found to decrease from several hundred volts to -100 V indicating the presence of defects edge leakage currents. The structural properties and characteristics of the resulting defects in the schottky contact layer are discussed.

In power electronics, the layout of a converter is known to have a significant impact on its conducted emissions. This paper focuses on layout modelling in order to predict converter compliance with EMC standards before prototype manufacturing. Inductive effects and capacitive parasitic effects should be considered and models in the form of equivalent circuits are required by time domain simulators. In recent works, a software was used to obtain an equivalent circuit of the inductive effects and analytic calculations were performed to add equivalent capacitors. In this paper a single software is used to generate a model which includes both capacitive and inductive effects. The existing method and the proposed one show very similar results and fit well with experimental results. The proposed method requires less efforts and is more scalable since it can be applied to complex geometries.

Today inverter system is one of the enabling technologies for efficiently harnessing energy from renewable energy sources (Solar, Wind, etc.,) and also for high reliable grid interfacing systems. With the advancements in power electronics, inverter conversion efficiency pushed to 98%, also PV is becoming a major renewable energy source globally. Nevertheless, the reliability performance of PV inverter is of high concern. Different environmental factors like solar irradiance, ambient temperature (also called Mission Profile) affect the reliability performance of PV inverter. Environmental conditions vary from location to location. Hence to quantify the reliability performance of PV inverter all these factors need to be considered. In this paper reliability performance of PV inverter is evaluated considering environmental factors and geographical locations. For the reliability evaluation, a 1-ϕ, 3-kW grid connected PV system is developed in PLECS. Full bridge PV inverter with 600V/30A IGBT is employed as the interface between grid and PV source. Real time mission profile data of one-year logs at India (Relatively hot climate) and Denmark (Relatively cold climate) to account for environmental factors and geographical locations during the reliability performance evaluation of PV inverter. Monte Carlo simulation is used to generate a population of 20000 samples with 5% variation. Lifetime for 20000 samples is calculated and fitted in Two Parameter Weibull distribution. B10 lifetime is calculated at two locations. The results of this paper reveal that environmental factors and geographical locations have a significant impact on PV inverter reliability performance.

Monitoring of underwater pipelines through wireless sensor nodes (WSNs) is an important area of research especially for locations such as underground or underwater pipelines, where it is costly to replace batteries. In this study, a finite element sensitivity and comparative analysis for piezoelectric (PZT) energy harvester operating in a fluid flow is done to power underwater in-pipe WSNs. Two types of bluff bodies D and I-shaped are used for comparison. Finite element simulations results show that PZT energy harvester having I-shaped bluff body produces 2.24 mW, while energy harvester having D-shaped bluff body has the capacity to produce only 0.82 mW of power. I-shaped bluff body have significant impact on the performance of pipe and it introduces 6 times more head loss than D-shaped bluff body to maintain regular flow of pipe for the same fluid domain. It is concluded from the analysis that 12 PZT cantilevers in parallel arrangement are needed to maintain 4096 bits per second (bps) transmission of 512-Byte data packet once per 5 minutes with the piezoelectric harvester, using an integrated 7.1 J super capacitor that can fit into the bluff body together with the power electronics and acoustic transceiver.

The usage of various inverters in various industries has gained considerable attention in the power electronics industry in recent years. The harmonic distortion that is induced by various renewable energy sources, along with the growing use of nonlinear loads and power electronic devices, has a significant impact on the distribution system. This is because of the rise in penetration of various renewable energy sources and the usage of nonlinear loads and power electronic devices. In addition, distributed generation (DG) units with inverters (such as solar (PV) and wind turbines) that are integrated into distribution networks are viewed as significant harmonic producers that have substantial adverse effects on power quality. The power quality in the system suffers because of these generators. This study proposes a method of harmonic mitigation for addressing power quality problems that are present in distribution systems as a solution to the challenges that have been found. These concerns have been brought to light as a result of previous research. The standard two-level and three-level inverters were the basis for the development of the multilevel inverter (MLI), which was meant to address their shortcomings. One of the effective technologies that can maintain constant performance is the hybrid power generating system. A hybrid energy system has several benefits, including high dependability, cheap cost and minimal emissions. When used in a hybrid power production system, the reduction of total harmonic distortion (THD) becomes absolutely necessary (HPGS). In this context, the research provides a novel approach for high-performance quantum computing called quantum coyote optimization algorithm-based THD reduction (QCOA-THDR). The QCOA-THDR approach that has been presented has been tested with several converters, including SEPIC, buck–boost and Cuk converters. Additionally, the proportional as well as the integral gain variables of the proportional integral (PI) controller are set in order to achieve decreased total harmonic distortion (THD). In addition, the QCOA system is formed by combining the ideas of quantum computing (QC) with the traditional COA. This is how the QCOA system comes to exist. A limited number of simulations were run, and the results are being analyzed from a variety of perspectives in order to investigate the improved effects that the QCOA-THDR approach has on data. The QCOA-THDR method was shown to have superior results than the more modern techniques, as shown by the comparison research.

The main function of the dynamic scan and stare imaging system is to quickly and continuously search a large area and perform high-resolution imaging. To eliminate image motion during the scanning process, this paper proposes an image motion compensation control method with dual-channel control. First, an improved model-assisted active disturbance rejection control is proposed, in which an auxiliary model is integrated into the algorithm to improve the control accuracy and response speed of the rotation rate of the platform. Second, a fast steering mirror (FSM) is introduced into the control system to compensate for the scanning speed and multiple disturbances. By adopting the amplitude frequency characteristics of the tracking differentiator, a parallel tracking differentiator filter is designed to suppress the interference of gyroscope noise on the FSM. When the system is disturbed by multiple frequency disturbances, the residual error of the image motion compensation is less than the spatial angular resolution of one pixel through the dual-channel stable control of the platform and the FSM. In the scan imaging experiment results, the average value of the grayscale variance function for the compensated images is close to 90% that of the static reference images.

This paper discusses the planning and preparation process for drilling and completing a 10km departure well at the Wytch Farm Oilfield in Southern England. An 8km departure well was drilled at Wytch Farm during 1995. At the time, this was at the limit of drilling operations. Some fundamental changes involving new technology, operational practices and techniques have been necessary to enable this well to be drilled. More specifically, the paper will describe the directional drilling techniques necessary to enable the reservoir interval to be accessed. Research and development work performed by the drilling team to identify mechanical limitations in drilling operations at this departure are also examined. This includes a comprehensive review of offset well data to determine friction factors for all operations and concomitant measures adopted to limit rotary torques and drags to workable levels. The other major focus of this paper is to appreciate the mechanism by which drilling muds are lost to the permeable reservoir and describe methodologies employed to overcome this problem. The paper will also discuss recent experience with the application of partially floating casing, rotary steerable drilling systems and running and cementing long liners. Completion and intervention challenges are also examined with an analysis of future requirements. Introduction The development of the offshore extension of the BP operated Wytch Farm Oilfield, located on the South coast of Britain, utilising extended reach (ER) wells into the offshore part of the Sherwood sandstone reservoir has been extensively documented in a series of technical papers [1], [2] and [3]. (Figure 1). The current phase of the development is to tap into significant reserves located at reservoir departures in excess of 10km. The Drilling Challenge. The section of the reservoir targeted by this Ultra-Reach well (Measured Depth : True Vertical Depth ratio >5), M-11, lies between 8km and 10km departure from the 'M Wellsite' where the Deutag T-47 rig is located. This site, specially constructed to access the offshore portion of the reservoir currently contains 10 extended reach wells and yields over half of the total 110,000 bopd production at Wytch Farm. The challenge is to safely and efficiently drill and complete a 10km departure well into the target area to access oil in place of 24mm STB. A single horizontal well into this target is expected to recover some 25–35% of these reserves. Although this is likely to be the most expensive well drilled at Wytch Farm, the significant reserves that it will access are critical to the long term profitability of the field. The well design is the culmination of over a year's evaluation, design and planning, providing an excellent test of the industry's capabilities. Successful delivery of this well will have a significant impact on the industry to access reserves that a decade ago would have required major capital expenditure, in the shape of new facilities, to recover. P. 191^