Power Factor Improvement Research Articles

Enhanced Thermoelectric Performance of p-Type Mg3-xZnxSb2/Sb Composites: The Role of ZnSb/Sb Composites.

Mg3Sb2-based Zintl compounds have garnered recent attention as promising materials for thermoelectric applications due to their low thermal conductivity and high zT values as n-type materials. However, the zT values of p-type materials are lower compared to their n-type counterparts. Through a straightforward process involving cold pressing and evacuating-and-encapsulating sintering, we have successfully synthesized a variety of p-type Mg3-xZnxSb2/Sb composites by adding the ZnSb-4%Sb composite into the Mg3Sb2 host material. Structural analyses have provided insights into the role of the ZnSb-4%Sb composite, demonstrating its significance in Zn doping on the Mg sites and Sb acting as an additive in the composite. The introduction of Zn on the Mg tetrahedral sites enhances the concentration of carriers, while the presence of highly conductive Sb grains facilitates the movement of charge carriers between adjacent Mg3-xZnxSb2 grains, thereby promoting mobility. Consequently, the electrical resistivity of the Mg3-xZnxSb2/Sb composites decreases as the Zn content increases. At 710 K, the Mg1.91Zn1.09Sb2/Sb composite exhibits the lowest resistivity, measuring 5.1 mΩ-cm, which is 46 times lower than that of the Mg3Sb2 host. Furthermore, the zT value of the Mg3-xZnxSb2/Sb composites increases with higher Zn content (x), benefiting from a combination of an improved power factor and reduced thermal conductivity. Significantly, our straightforward fabrication process enables us to achieve a maximum zT value of 0.58 at 710 K for the Mg1.91Zn1.09Sb2/Sb composite. This achievement can primarily be attributed to the 8-fold enhancement in power factor compared to the Mg3Sb2 host.

Fractional delay Newton structure for Lagrangian interpolation in PV integrated grid connected system

SummaryThis paper proposes a fractional delay (FD) Newton structure for Lagrangian interpolation in single phase grid integrated photovoltaic (PV) system. The structure has been designed for achieving shunt compensation and as a phase locked loop circuit for synchronization. The designed controller performs multiple tasks of feeding the active power to meet the load demand and simultaneously providing reactive power compensation, power factor improvement, and compensating other power quality voltage and load current harmonics. Further, synchronization poses a severe challenge in integrating the PV power electronic converters to the grid. The FD filter is used to discretize the continuous time signal at any time instant using interpolation algorithm employing the non‐integral value of the sampling rate delays. The FD delay filter is made adaptive and self‐learning by using least mean square algorithm. The designed synchronization technique meets the objective of faithfully tracking the phase of the grid voltage under all grid disturbances such as under voltage, overvoltage, frequency variations, and phase angle disturbances in a precise manner.

Implementation of Power Factor Correction using Asynchronous Boost Converter on Single Phase Full-Bridge Diode

In various industrial applications, the use of a power supply that uses a conventional diode single-phase rectifier topology results in high harmonic values in the electricity distribution system. One of the real impacts of this harmonic value is the heating of the electric power system equipment and power losses. High rms current values due to harmonics often cause problems in protection settings in addition to efficiency problems. The percentage value between the total harmonic component and the fundamental component is called THD (Total Harmonic Distortions). Therefore, in this study an asynchronous dc-dc boost converter is connected to the output side of a single-phase diode rectifier which is capable of improving power factor and low harmonics. So that a THD value of less than 15%, PF (Power Factor) = 0.92-1 and a sinusoidal input current can be obtained. The implementation results show that the PFC (Power Factor Correction) method can work well on single-phase diode rectifiers.

The Economics of Power Factor Improvement

The Economics of Power Factor Improvement

Predictive Power Control of PMSG based WECS: Development and Implementation for Smooth Grid Synchronisation, Balanced and Unbalanced Grid

In this paper, the distributed generation unit is controlled to operate in both stand-alone (SA) and grid-connected (GC) modes and offers a smooth transition between these modes using the model predictive control scheme. The permanent magnet synchronous generator (PMSG), along with a 2-level back-to-back converter, is named a DGU. A simple and intuitive approach using predictive control is presented in a stationary reference frame for a load-side converter (LSC). A voltage control loop is used during SA mode to fix the voltage and frequency at the load end. The smooth synchronization technique is developed without a phase-locked loop. During GC, a predictive power control regulates active and reactive power during the symmetry and unbalanced grid voltage conditions. The designed strategy makes the power factor improvement, reduction of grid current harmonics, and elimination of twice grid frequency ripple from power during grid unbalance possible. This work has proposed a solution to reduce the overall computational burden on the processor by eliminating the state prediction in each sampling period. The machine-end converter control is formulated in the rotor flux reference frame to keep the power flow across the dc-link capacitor constant. Comprehensive experiments are conducted with the designed scaled laboratory prototype to successfully validate the control’s theoretical claim.

Enhanced electrical and mechanical properties of Bi2Te3-based thermoelectric thick films enabled by a practical dynamic regulation strategy

The application of high-density and high-performance micro thermoelectric devices is still in its infancy, mainly restricted by the low performance of Bi2Te3-based thick film as well as the limited device integration. In this study, we proposed a dynamic regulation strategy to simultaneously strengthen the thermoelectric and mechanical properties for n-type Bi2Te3-based thick films. The effects of growth temperature and time on thermoelectric properties have been firstly explored. As the thermoelectric properties exhibit consistent degradation with increasing thickness at static growth temperature, an effective rising temperature method is introduced to dynamically regulate the nucleation rate and growing diffusion ability. Thus, the grain refinement with compact texture structure leads to a relatively large carrier mobility (77.1 cm2·V−1·s−1) and appropriate concentration (5.25 × 1019 cm−3) as well as further 12% improvement of power factor with an average value up to 12.0 μW·cm−1·K−2 over a wide temperature ranging from 313 K to 453 K. Furthermore, significant enhancement of mechanical property is also achieved with high elastic modules (56.03 GPa), hardness (0.63 GPa) and large energy dissipation capacity to prevent micro-cracks. This study provides a practical solution with dynamic temperature control to fabricate high-performance Bi2Te3 thick films with enhanced mechanical property and processing feasibility for micro thermoelectric devices.

A Power Factor Profile-Improved EV Charging System Using Bridgeless Buckboost-Cuk Converter

This article presents a power factor profile-improved bridgeless buckboost-Cuk converter-fed battery charging system for electric vehicle applications. The conventional charging system does not use any power factor improvement stage, due to which the supply current harmonics are very high and violate IEC-61000-3-2 standard guidelines. To meet the international standard guidelines, a compact and efficient power factor-improved converter stage is necessary. The power factor-improved converter in the present work uses a fourth-order Cuk converter during negative semi-cycle and a second-order buckboost converter during positive semi-cycles of the supply voltage. The amalgamation of a second- and fourth-order converter in a bridgeless configuration reduces the system’s order concerning a bridgeless Cuk converter-based system and also eradicates the need for a diode-based bridge rectifier (DbBR). Due to the presence of an input side inductor, there is no requirement for an external filter like a bridgeless buckboost converter-based scheme. The input inductor in the present scheme performs twin action; it reduces harmonic disturbances in the mains current during the negative semi-cycle and also works with capacitor CP to filter harmonics and improve the mains current profile during the positive semi-cycle of the mains voltage. The power factor-improved converter in the present work is operated in discontinuous conduction mode (DCM). This eliminates the requirement for extra sensors compared to continuous conduction mode (CCM). The scheme also eliminates the need for two extra back-feed diodes which are generally required in bridgeless configuration loop completion during different semi-cycles of mains voltage. In the present scheme, the work of back-feed diodes is done by the anti-parallel inherent diodes of the switches. In the second stage, a high-frequency-operated flyback converter is used which not only boosts the battery current profile but also provides the electrical isolation between the supply side and load. This article also presents the detailed stability analysis and math modeling of the presented bridgeless buckboost-Cuk converter. The presented system is built on MATLAB/Simulink, and results are presented and discussed to validate the system performance.

Assessment of Converter Performance in Hybrid AC-DC Power System under Optimal Power Flow with Minimum Number of DC Link Control Variables

This paper presents a strategy to evaluate the performances of converter stations under the optimized operating points of hybrid AC-DC power systems with a reduced number of DC link variables. Compared to previous works reported with five DC-side control variables (CVs), the uniqueness of the presented optimal power flow (OPF) formulation lies within the selection of only two DC-side control variables (CVs), such as the inverter voltage and current in the DC link, apart from the conventional AC-side variables. Previous research has mainly been focused on optimizing hybrid power system performance through OPF-based formulations, but has mostly ignored the associated converter performances. Hence, in this study, converter performance, in terms of ripple and harmonics in DC voltage and AC current and the utilization of the converter infrastructure, is evaluated. The minimization of active power loss is taken as an objective function, and the problem is solved for a modified IEEE 30 bus system using a recently developed and very efficient Archimedes optimization algorithm (AOA). Case studies are performed to assess the efficacy of the presented OPF model in power systems, as well as converter performance. Furthermore, the results are extended to assess the applicability of the proposed model to the allocation of photovoltaic (PV)-type distributed generations (DGs) in hybrid AC-DC systems. The average improvement in power loss is found to be around 7.5% compared to the reported results. Furthermore, an approximate 10% improvement in converter power factor and an approximate 50% reduction in ripple factor are achieved.

Power factor correction for energy efficient at public hospital of Manokwari

The power factor grades are an indicator to determine the effectiveness of the electric power either distributed or used by consumers. A high power factor indicates that the electrical loads are using energy efficiently. Due to the increase in inductive load, there will be a decrease in the power factor, which in turn affects the distribution of electrical energy. In this research, an investigation has been carried out to observe the background that influences the low power factor at public hospital (RSUD) of Manokwari and recommend the need for a basis for improving the power factor at the hospital. Primary data on lighting and electrical equipment, along with their respective electric power capacities and power factors, are collected and measured onsite. Then the data is analysed based on the theoretical basis of power factor improvement. Based on the investigation, there are two focus points in the hospital to be observed, i.e., motor pumps and total load at the main panel. The calculation results show that pump motors 2 and 3 need to be compensated by increasing the power factor to 0.9 so that reactive power is reduced to 1.42 kVAR and 1.24 kVAR, respectively. In the same way, apparent power can also be upgraded to 0.85 kVA and 1.46 kVA by installing bank capacitors of 30.35 mF and 26.63 mF, respectively. On the other hand, the largest load connected to the main panel needs to be corrected to reduce the reactive power and apparent power to 17.86 kVAR and 9.5 kVA through the installation of a capacitor bank of 387.75 mF. This correction will increase energy efficiency while gaining economic benefits on both electricity bills and waiving penalties.

Fractional fuzzy PI controller using particle swarm optimization to improve power factor by boost converter

The power circuit of AC voltage controller capable of operating at a leading, lagging, and unity power factor is studied by a lot of researchers in the literature. Circuits working with high switching frequency are known as power factor correctors (PFCs). The single-phase boost converter has become the most popular topology for power factor correction (PFC) in general purpose power supplies. Power factor correction circuit provides conventional benefits to electric power systems. The benefits are the reduction of power factor penalty and utility bill and power loss. Therefore, a boost converter power factor correction scheme is presented in this paper. A PI, fuzzy logic PI and fractional order PI (FOPI) controllers are used to fix an active shaping of input current of the circuit and to improve the power factor. The controller parameters (coefficients) are optimized using the Particle Swarm Optimization (PSO) algorithm. Average current mode control (ACMC) method is used in the circuit. The converter circuit consists of a single-phase bridge rectifier, boost converter, transformer and load. A mathematical model of the plant is required to design the PI controller. A model for power factor correction circuit is formed in MATLAB/Simulink toolbox and a filter is designed to reduce THD value. The proposed model is simulated using a combination of PI, fuzzy logic and FOPI controllers. The control scheme is applied to 600 Watt PFC boost converter to get 400 Volt DC output voltage and 0.99 power factor. The input voltage is 230 VRMS with 50 Hz. The combination of FOPI and PI controller has the best solution to control the power factor according to PI and fuzzy controllers.

Design and Implementation of Switched Capacitor Banks Controlled by a Programmable Logic Controller for Power Factor Improvement of Three-Phase Induction Motors

Industries widely use three-phase inductive loads, such as induction motors, due to their cost-effectiveness, low maintenance, reliability, and durability. However, these loads decrease the power factor, which leads to power wastage, higher billing costs, and penalties from electric power supply companies. To address this issue, a system has been developed that employs a programmable logic controller (PLC) to enhance the power factor of three-phase loads, which reduces the plant's operating costs and lessens the demand for electricity supply from the utility side. The system combines hardware and software components. The software includes logic-based PLC programming that controls the sequence of operations step by step, whereas hardware consists of power and control circuits and protective devices. When an inductive load is added to the system, the PLC reads the input signal from the magnetic contactor's contactor coil connected with the motor and sends an output signal to the corresponding contactor coil of the magnetic contactor to switch the appropriate capacitor bank to enhance the power factor. This paper discusses the experimental results for seven cases utilizing different load combinations with and without the developed system. Thus, energy management requires improving the load's power factor, and the PLC is used as a power factor controller (PFC) for many industrial control applications.

Reactive Power Optimization of Power System Based on Particle Swarm Optimization Algorithm

With the popularization and development of the Power System (PS), the power factor and stability issues of the PS are becoming increasingly prominent. The Reactive Power (RP) in the PS has a significant impact on system stability and efficiency. Therefore, how to optimize the RP in the PS, improve power factor and stability, has become one of the research hotspots in the field of power. This paper aims to solve the problem of RP Optimization (OPT) in PS, and optimize the size and distribution of RP by using particle swarm OPT, so as to improve the stability and efficiency of PS. Through experimental testing, it was found that the Algorithm (ALG) has good performance in RP OPT problems and has great potential for application in PS OPT. The experimental results show that among these five sets of results, the value range of objective function 1 ranges from 156.75 kW^2 to 162.46 kW^2, indicating that different RP compensation capacities have different effects on the magnitude of RP loss.

Reactive power (VAR) compensation techniques in high voltage transmission lines

Management of reactive power and voltage control constitute part of the major challenges in a power system. Appropriate reactive power management and control solves power quality problems, reduce losses, improve power factor, maintained a balanced voltage profile at all power transmission levels, improved system efficiency and stability. This paper examined the brief idea about the mode of operations, design characteristics of various types of reactive power compensation techniques. These techniques are used to improve the performance of AC transmission & distribution systems. They enhance the stability of the AC transmission system by increasing the active power that can be transmitted thereby enhancing the overall working of the electric power system.

Automatic Power Factor Correction using Microcontroller

Power quality is a key factor in all industrial and many more applications. An industry need to maintain certain power quality standard during day-to-day work for variety of applications. Power quality of electricity provided by utilities is also vital aspect. The best power quality helps to increase the overall production and gets rid of any sort of technical problems reducing cost of energy. The mains power factor is one of the important parameter which decides the quality of power. When the need of reactive power becomes more, power factor decreases, reducing the efficiency of power system. Therefore, there is need to add capacitance of required value when power factor goes below the specified value, preferably 0.92. Addition of required capacitors reduces the losses improving power factor. The paper proposes digitally controlled topology for performing Automatic Power Factor Correction to improve power quality. The design and simulation of Automatic Power Factor Correction system using microcontroller (AT89S52/C51) has been presented in the paper. The system power factor has been monitored using power factor transducer followed by Arduino microcontroller which control the switching of capacitor banks in order to compensate reactive power and bring power factor near to unity enhancing power quality. The simulation results are also presented in the paper.

Voltage regulation using three phase electric spring by fuzzy logic controller

Introduction. The renewable energy sources such as solar and wind power have increased significantly in recent years. However, as the generation of renewable energy has become more integrated, its intermission and instability have a major impact on the power system’s stability, such as voltage instability and frequency flicker. Purpose. In order to address the different power quality issues brought on by intermittent and unreliable renewable energy sources, electric spring offers a novel solution. It was proposed as a technique for regulating load and adjusting output power. For the integration of electric springs with noncritical loads, a contemporary control mechanism is described in this paper. Novelty. The suggested work is innovative in that it presents an improved control technique that efficiently maintains voltage stability as voltage changes. Method. The proposed technique is based on an analysis of the initial conditions and input data for developing fuzzy rules for calculating compensating voltages in relation to the difficulties. Results. This suggested fuzzy controller will be able to maintain the regular operation of the electric spring of power output control stability as well as continuing to provide power factor improvement and voltage control for significant loads, including the home’s protection system. Practical value. A detailed study of typical voltage regulation is undertaken, supported by simulation results, to demonstrate the effectiveness of the applied control scheme in cancelling the corresponding issues with power quality.

DER integrated BTB-VSI based DSTATCOM for PQ enhancement

ABSTRACT This article demonstrates the performance of back-to-back connected voltage source inverter (BTB-VSI)-based distribution static compensator (DSTATCOM). In the proposed system, a three-phase three wire electrical utility system (EUS) is integrated with distributed energy resources (DER) through BTB-VSI. It has drawn more attention due to enhanced active power filtering, simple design procedure and performs reliable operation. The objectives of the research work is to provide clean power for weak EUS with improved power quality (PQ) such as, better voltage regulation, improved power factor (P.F), reduced total harmonic distortion (THD), balanced voltage at point of common coupling (PCC) and better optimal active power flow control (OAPFC), and so on. An artificial neurocontrol technique Kernel Hebbian Least Mean Square (KHLMS) is chosen to determine the accurate reference source current for operation of voltage source inverter (VSI). The BTB-VSI performance is investigated on both shunt compensation and OAPFC. The proposed system is converted to a simulation model and hardware unit using MATLAB/Simulink software and SPARTAN−6 field programmable gate arrays (FPGA) controller. Finally, the Simulation and experimental results illustrate that the shunt compensating ability with OAPFC of BTB-VSI performs better over VSI as per IEEE Std 1159–2019 grid code.

Roles of concentration-dependent Cu doping behaviors on the thermoelectric properties of n-type Mg3Sb1.5Bi0.5

Large Seebeck coefficients induced by high degeneracy of conduction band minimum, and low intrinsic lattice thermal conductivity originated from large lattice vibrational anharmonicity render Mg3Sb2 as a promising n-type thermoelectric material. Herein, we demonstrated unique concentration-dependent occupation behaviors of Cu in Mg3.4Sb1.5Bi0.49Te0.01 matrix, evidenced by structural characterization and transport property measurements. It is found that Cu atoms prefer to enter the interstitial lattice sites in Mg3Sb2 host with low doping level (Mg3.4Sb1.5Bi0.49Te0.01 + x% Cu, x < 0.3%), acting as donors for providing additional electrons without deteriorating the carrier mobility. When x is larger than 0.3%, the excessive Cu atoms are inclined to substitute Mg atoms, yielding acceptors to decrease the electron concentration. As a result, the electrical conductivity of the Mg3.4Sb1.5Bi0.49Te0.01 + 0.3% Cu sample reaches 2.3 × 104 S/m at 300 K, increasing by 300% compared with that of the pristine sample. The figure of merit zT values in the whole measured temperature range are significantly improved by the synergetic improvement of power factor and reduction of thermal conductivity. An average zT ∼1.07 from 323 K to 773 K has been achieved for the Mg3.4Sb1.5Bi0.49Te0.01 + 0.3% Cu sample, which is about 30% higher than that of the Mg3.4Sb1.5Bi0.49Te0.01 sample.

PI Controller Based Automatic Power Factor Correction (APFC) Using Capacitor Bank

Abstract Power factor plays an important role in electrical industries. Low power factor results in loss of power and poor handling capacity. This factor can be overcome by using capacitors in parallel to the load. Since capacitor draws a leading while inductor draws a lagging current, hence by adjusting capacitor banks parallel to the load, it will level the power factor in the line. Earlier, the process of power factor improvement was done through manual connection of capacitor bank. Later a power factor corrector named the automated power factor corrector (APFC) was proposed. It uses a switched capacitor circuit to improve power factor. In this research, the power factor value from the load is measured and it also includes the installation of APFC unit using a PI controller. The design of this auto-adjustable power factor correction scheme is to ensure that the grid power system always operates under the specified power factor. Actual work of APFC is that it selects the capacitor bank for power factor improvement. The capacitor bank block will choose automatically to further improve the power factor. This process goes on until the required power factor is obtained. Later on, this will automatically turn off the connection between the capacitor bank and the circuit. Furthermore, power saving with power factor after improvement is also discussed in the paper. Here APFC plays a key role in order to decrease the time taken to correct the power factor, which is ultimately beneficial to increase the efficiency of the motors and all inductive loads.

Grid-Side Current Harmonic Suppression and Power Factor Improvement Using q – Axis Damping Current Injection for PMSM Drives Without Electrolytic Capacitor

The dc-link film capacitor with low-capacitance in permanent magnet synchronous motor (PMSM) drives without electrolytic capacitor will not only reduce the system stability, but also generate LC resonance with the grid-side filter inductor, which is the important reason for high grid side harmonic current and low power factor. In this paper, a grid side current harmonic suppression strategy using q-axis damping current injection is proposed to address these issues of PMSM drives without electrolytic capacitor. The analysis of the transfer function based on the simplified circuit of the drive shows the instability and LC resonance of the system. The feedforward modification method based on the difference between the quasi-dc-link voltage and the dc-link voltage is applied to improve the system performance. Meanwhile, the specific implementation of the proposed method by injecting damping current into the q-axis is introduced. In addition, a phase disturbance angle is introduced in the proposed control strategy to adjust the phase of quasi-dc-link voltage. By properly adjusting the phase disturbance angle, the conduction angle of the single-phase uncontrolled rectifier bridge can be effectively expanded, and the grid side power factor can be further improved. Experiments on a PMSM drive with the low-capacitance of dc-link film capacitor are carried out to verify the effectiveness of the proposed method.

Pulse Width Modulation Inverter Control Methods-A Comprehensive Study

Harmonics in electrical supply refers to the distortion of the normal electrical waveform due to the presence of frequencies that are multiples of the fundamental frequency. The presence of harmonics in electrical supply can lead to a number of problems, including: Overheating of equipment, Power quality issues, Extra energy consumption etc. This research aims to provide a cost-effective solution to reduce harmonics in three phase inverters and improve power factor without using any hardware components such as filters and multi-level inverters and by simply changing control pulses of the inverter switches. This research provides a comparison of three most popular inverter control techniques SPWM control, THPWM control and SVPWM control techniques of three phase inverters. All these techniques were compared with the help of MATLAB-SIMULINK and the best control technique with lower order harmonics and less power factor was determined.