Dispersed Wind Power Planning Method Considering Network Loss Correction with Cold Weather

In order to play a positive role of decentralised wind power on-grid for voltage stability improvement and loss reduction of distribution network,a multi-objective two-stage decentralised wind power planning method is proposed in the paper,which takes into account the network loss correction for the extreme cold region.Firstly,an electro-thermal model is introduced to reflect the effect of temperature on conductor resistance and to correct the results of active network loss calculation;secondly,a two-stage multi-objective two-stage decentralised wind power siting and capacity allocation and reactive voltage optimisation control model is constructed to take account of the network loss correction,and the multi-objective multi-planning model is established in the first stage to consider the whole-life cycle investment cost of WTGs,the system operating cost and the voltage quality of power supply,and the multi-objective planning model is established in the second stage.planning model,and the second stage further develops the reactive voltage control strategy of WTGs on this basis,and obtains the distribution network loss reduction method based on WTG siting and capacity allocation and reactive power control strategy.Finally,the optimal configuration scheme is solved by the manta ray foraging optimisation(MRFO)algorithm,and the loss of each branch line and bus loss of the distribution network before and after the adoption of this loss reduction method is calculated by taking the IEEE33 distribution system as an example,which verifies the practicability and validity of the proposed method,and provides a reference introduction for decision-making for the distributed energy planning of the distribution network.

Assessment of Axial Power Peaking Factors in GHARR-1 LEU Core: A Decadal Simulation Analysis

This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the MCNPX code for analysing neutron behavior and the PARET/ANL code for understanding power variations, to get a clearer picture of the reactor’s performance. The analysis covers the initial six years of GHARR-1’s operation and includes projections for its whole 60-year lifespan. We closely observed the patterns of both the highest and average PPFs at 21 axial nodes, with measurements taken every ten years. The findings of this study reveal important patterns in power distribution within the core, which are essential for improving the safety regulations and fuel management techniques of the reactor. We provide a meticulous approach, extensive data, and an analysis of the findings, highlighting the significance of continuous monitoring and analysis for proactive management of nuclear reactors. The findings of this study not only enhance our comprehension of nuclear reactor safety but also carry significant ramifications for sustainable energy progress in Ghana and the wider global context. Nuclear engineering is essential in tackling global concerns, such as the demand for clean and dependable energy sources. Research on optimising nuclear reactors, particularly in terms of safety and efficiency, is crucial for the ongoing advancement and acceptance of nuclear energy.

Period-doubling bifurcation in two-stage power factor correction converters using the method of incremental harmonic balance and Floquet theory

In this paper, period-doubling bifurcation in a two-stage power factor correction converter is analyzed by using the method of incremental harmonic balance （IHB） and Floquet theory. A two-stage power factor correction converter typically employs a cascade configuration of a pre-regulator boost power factor correction converter with average current mode control to achieve a near unity power factor and a tightly regulated post-regulator DC-DC Buck converter with voltage feedback control to regulate the output voltage. Based on the assumption that the tightly regulated postregulator DC-DC Buck converter is represented as a constant power sink and some other assumptions, the simplified model of the two-stage power factor correction converter is derived and its approximate periodic solution is calculated by the method of IHB. And then, the stability of the system is investigated by using Floquet theory and the stable boundaries are presented on the selected parameter spaces. Finally, some experimental results are given to confirm the effectiveness of the theoretical analysis.

A Data Driven Security Correction Method for Power Systems with UPFC

The access of unified power flow controllers(UPFC)has changed the structure and operation mode of power grids all across the world,and it has brought severe challenges to the traditional real-time calculation of security correction based on traditionalmodels.Considering the limitation of computational efficiency regarding complex,physical models,a data-driven power system security correction method with UPFC is,in this paper,proposed.Based on the complex mapping relationship between the operation state data and the security correction strategy,a two-stage deep neural network(DNN)learning framework is proposed,which divides the offline training task of security correction into two stages:in the first stage,the stacked auto-encoder(SAE)classification model is established,and the node correction state(0/1)output based on the fault information;in the second stage,the DNN learningmodel is established,and the correction amount of each action node is obtained based on the action nodes output in the previous stage.In this paper,the UPFC demonstration project of NanjingWest Ring Network is taken as a case study to validate the proposed method.The results show that the proposed method can fully meet the real-time security correction time requirements of power grids,and avoid the inherent defects of the traditional model method without an iterative solution and can also provide reasonable security correction strategies for N-1 and N-2 faults.

Performance Evaluation of a Permanent Magnet Electric-Drive- Reconfigured Onboard Charger with Active Power Factor Correction

This paper presents a comprehensive charging operation for an electric-drive-reconfigured onboard charger(EDROC)with active power factor correction(APFC).The charging topology exclusively utilizes the three-phase permanent magnet synchronous motor(PMSM)propulsion system as a three-channel boost-type converter in which only a contactor and a small diode bridge are added.First,the operation scenario of the EDROC is introduced.Second,the relationship between electromagnetic torque and rotor position is investigated.Third,the current ripple cancellation of the EDROC is discussed in detail.Moreover,to implement the single-phase APFC along with charging voltage/current regulation of propulsion battery,control strategies including current balancing and synchronous/interleaving PWM strategies are incorporated.Finally,200W proof-of-concept prototype-based tests are conducted under different operation scenarios.

Method for measuring the low-frequency sound power from a complex sound source based on sound-field correction in a non-anechoic tank

Similar to air reverberation chambers, non-anechoic water tanks are important acoustic measurement devices that can be used to measure the sound power radiated from complex underwater sound sources using diffusion field theory. However,the problem of the poor applicability of low-frequency measurements in these tanks has not yet been solved. Therefore,we propose a low-frequency acoustic measurement method based on sound-field correction(SFC) in an enclosed space that effectively solves the problem of measuring the sound power from complex sound sources below the Schroeder cutoff frequency in a non-anechoic tank. Using normal mode theory, the transfer relationship between the mean-square sound pressure in an underwater enclosed space and the free-field sound power of the sound source is established, and this is regarded as a correction term for the sound field between this enclosed space and the free field. This correction term can be obtained based on previous measurements of a known sound source. This term can then be used to correct the mean-square sound pressure excited by any sound source to be tested in this enclosed space and equivalently obtain its free-field sound power. Experiments were carried out in a non-anechoic water tank(9.0 m × 3.1 m × 1.7 m) to confirm the validity of the SFC method. Through measurements with a spherical sound source(whose free-field radiation characteristics are known),the correction term of the sound field between this water tank and the free field was obtained. On this basis, the sound power radiated from a cylindrical shell model under the action of mechanical excitation was measured. The measurement results were found to have a maximum deviation of 2.9 d B from the free-field results. These results show that the SFC method has good applicability in the frequency band above the first-order resonant frequency in a non-anechoic tank. This greatly expands the potential low-frequency applications of non-anechoic tanks.

Power Factor Correction Rectifier with a Variable Frequency Voltage Source in Vehicular Application

This paper presents a PFCVF (Power Factor Correction) rectifier that uses a variable frequency source for alternators for electric and hybrid vehicles application. In such application, the frequency of the signal in the alternator changes according to the vehicle speed, more over the loading effect on the alternator introduces harmonic currents and increases the alternator apparent power requirements. To overcome these problems and aiming more stability and better design of the alternator, a new third harmonic injection technique is proposed. This technique allows to preserve a good THD (Total Harmonic Distortion) of the input source at any frequency and to decrease losses in semiconductors switches, thereby allowing more stability and reducing the apparent power requirements. A comparative study between the standard and the new technique is made and highlights the effectiveness of the new design. A detailed analysis of the proposed topology is presented and simulations as well as experimental results are shown.

A new high-performance AC/DC power factor correction switching converter based on one-cycle control technology and active floating-charge technology

A new family of converters,high-performance AC/DC power factor correction(PFC) switching converters with one-cycle control technology and active floating-charge technology,was derived and experimentally verified.The topology of a single-phase CCM and DCM Boost-PFC switching converter was also analyzed.Its operating prniciples and control methods were expounded.Based on these,a new type of AC/DC switching converter circuits for PFC combined with one-cycle control technology was presented herein.The proposed AC/DC switching converter significantly helps improve the converter efficiency and its power factor value.

Low-frequency oscillation of train-network system considering traction power supply mode

The low-frequency oscillation(LFO)has occurred in the train-network system due to the introduction of the power electronics of the trains.The modeling and analyzing method in current researches based on electrified railway unilateral power supply system are not suitable for the LFO analysis in a bilateral power supply system,where the trains are supplied by two traction substations.In this work,based on the single-input and single-output impedance model of China CRH5 trains,the node admittance matrices of the train-network system both in unilateral and bilateral power supply modes are established,including three-phase power grid,traction transformers and traction network.Then the modal analysis is used to study the oscillation modes and propagation characteristics of the unilateral and bilateral power supply systems.Moreover,the influence of the equivalent inductance of the power grid,the length of the transmission line,and the length of the traction network are analyzed on the critical oscillation mode of the bilateral power supply system.Finally,the theoretical analysis results are verified by the time-domain simulation model in MATLAB/Simulink.

The Security Correction of Large Consumers Long-Term Direct Power Trading Based on DC Power Transfer Distribution Factor

The experiments of large consumers direct power trading is conducting in china nationwide, and it’s important to the reform of electricity market. To compensated efficiencies in security correction of large consumers direct power trading, a novel security correction method based on DC power transfer distribution factor was proposed. Using the presented method to comply security correction, all the transactions that satisfy the specific requirements of maximizing social welfare are able to enter security correction process, and when the power of transmission line is out of limit, this method avoid the transaction which causes this problem is abandoned directly by introducing supplement transactions. The simulation has shown that the proposed security correction method of large consumers direct power trading based on DC power transfer distribution factor is effective.

Comparison and Evaluation of Power Factor Correction Topologies for Industrial Applications

Power factor correction is a major issue for all industries, since a typical industrial load is causing current delays, as well as higher order current harmonics. Power factor correction is often mandatory from the power companies, usually by charging the reactive power that the company consumes. Many solutions for power factor correction have been presented in the bibliography;in this paper, the most significant power factor correction topologies will be reviewed and simulated with SABER RD software. Finally, a prototype design will be presented, based on a mass/cost analysis of the selected topologies and with an aim to manufacture 10 kW modules. The main outcome of this work is the feasibility for an SME to manufacture a competitive modular power factor correction product for industrial applications.

Economic Improvement of Power Factor Correction: A Case Study

Power factor (PF) is simply an expression of energy efficiency, which is always expressed in terms of percentage. Technically, PF is a ratio of real power in Kilowatts to the apparent power, which is always expressed in kilovolts amperes. In AC power analysis, power is always expressed in three ways, the real power (P), reactive power (Q), and the apparent power (S). The real power is the work useful power, while the reactive power is the wasted power in the 3-phase AC system, and the apparent power is the vectorial sum of the two powers. The increase of reactive power will reduce the presence of real power, thus making the power to be more expensive. In this paper, we will analyze the importance of improving the power factor by applying a bank of capacitors to a case study in Lebanon. Analysis of the economic improvement in the application of power factor correction is carried out. The result shows a reduction of 12 percent in the total cost.

Correction Factor for Power Gain in Antenna Arrays

Antenna array gain is a relative measure of performance defined differently in various literature. Most definitions of gain are not power consistent, and thus cannot be used directly in link budget analysis. In this short paper, we present a power correction factor for common definitions of power gain of antenna arrays that allows them to be used in standard link budget calculations.

An Improved Non-isolated LED Converter with Power Factor Correction and Average Current Mode Control

A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input voltages ranging from 100 Vrms to 240 Vrms, the power factor correction and average current mode control methods operating in continuous current conduction mode are designed and implemented. With the LUMILEDS emitter type LEDs, a laboratory prototype is built and measured. And from the measured results, it could be concluded that the proposed driver has many better performances such as high power factor, low current harmonic, accurate average current control and switch protection.

New DCM Operated Single Phase Bridgeless Cuk Derived Converters for Power Factor Correction

This paper presents a power factor corrected (PFC) new bridgeless (BL) Cuk Topologies for low power applications. A BL configuration of Cuk converter is proposed which eliminates the usage of diode bridge rectifier at the front end of the PFC converter, thus reducing the switching and conduction losses coupled with it. This new BL Cuk converter has two semiconductors switches. The current flow during each switching cycle interval of the converter reduces the conduction losses compared to the conventional Cuk PFC converter. It also reduces the input current ripple and Electromagnetic Interference (EMI). The inrush current during the starting period is limited and the input, output currents of the converter are continuous with minimum current ripple. Hence it is preferred mostly compared to other PFC circuits. The proposed topology works in the Discontinuous Conduction Mode (DCM) with simple control circuitry to achieve almost a unity power factor with less distortion in the input AC current. The switching of the power switches is done under zero current. The proposed PFC topologies are theoretically investigated and performance comparisons are made with the conventional rectifiers. The proposed PFC converter is simulated in MATLAB/SIMULINK with Fuzzy Logic Controller (FLC) and results are demonstrated to evaluate the effectiveness of the controller.

Single-stage active clamp power factor correction AC/DC converter

A simple single-stage AC/DC converter circuit with active clamp is presented. The operation theory and state are analyzed. The experimental results show that the voltage across main switch can be clamped to a certain value,and zero voltage switching (ZVS) can be achieved. The voltage stress and switching loss are both decreased. In range of the whole load,power factors can be always more than 97%,and the highest efficiency can reach 88%.

A novel arc welding inverter with unit power factor based on DSP control

A novel inverter power source is developed characterized with constant output current and unit power factor input. Digital signal processor （ DSP ） is used to realize power factor correction and control of back-stage inverter bridge of the arc welding inverter. The fore-stage adopts double closed loop proportion and integration （PI） rectifier technique and the back- stage adopts digital pulse width modulation （ PWM） technique. Simulated waves can be obtained in Matlab/Simulink and validated by experiments. Experiments of the prototype showed that the total harmonic distortion （THD） can be controlled within 10% and the power factor is approximate to 1.

Spectral Dependence on the Correction Factor of Erythemal UV for Cloud, Aerosol, Total Ozone, and Surface Properties: A Modeling Study

Radiative transfer modal simulations were used to investigate the erythemal ultraviolet （EUV） correction factors by separating the UV-A and UV-B spectral ranges. The correction factor was defined as the ratio of EUV caused by changing the amounts and characteristics of the extinction and scattering materials. The EUV correction factors （CFEUV） for UV-A [CFEUV（A）] and UV-B [CFEUV（B）] were affected by changes in the total ozone, optical depths of aerosol and cloud, and the solar zenith angle. The differences between CFEUV（A） and CFEUV（B） were also estimated as a function of solar zenith angle, the optical depths of aerosol and cloud, and total ozone. The differences between CFEUV（A） and CFEUV（B） ranged from -5.0% to 25.0% for aerosols, and from -9.5% to 2.0% for clouds in all simulations for different solar zenith angles and optical depths of aerosol and cloud. The rate of decline of CFEUV per unit optical depth between UV-A and UV-B differed by up to 20% for the same aerosol and cloud conditions. For total ozone, the variation in CFEUV（A） was negligible compared with that in CFEUV（B） because of the effective spectral range of the ozone absorption band. In addition, the sensitivity of the CFEUVs due to changes in surface conditions （i.e., surface albedo and surface altitude） was also estimated by using the model in this study. For changes in surface albedo, the sensitivity of the CFEUVs was 2.9%-4.1% per 0.1 albedo change, depending on the amount of aerosols or clouds. For changes in surface altitude, the sensitivity of CFEUV（B） was twice that of CFEUV（A）, because the Rayleigh optical depth increased significantly at shorter wavelengths.

Fast-scale border collision bifurcation in SEPIC power factor pre-regulators

In this paper we report a kind of fast-scale instability occurring in the single-ended primary inductance converter （SEPIC） power factor pre-regulator, which is designed to operate in discontinuous conduction mode. Main results are given by exact cycle-by-cycle computer simulations as well as theoretical analysis. It is found that the instability phenomenon manifests itself as a fast-scale bifurcation at the switching period, which implies the occurrence of border collision bifurcation, or is related to the transition of the regular operating mode of the SEPIC. According to the theoretical analysis and simulation results, the effects of parameters on system stability, and the locations of the bifurcation points are confirmed. Moreover, the effects of such an instability on power factor and switching stress are also discussed. Finally, the occurrence of the asymmetric bifurcation locations is investigated. The results show that this work provides a convenient means of predicting stability boundaries which can facilitate the selection of the practical parameters.