Uniform Power Research Articles

Multi-objective based Hybrid Artificial Intelligence Controlled Parallel Inverter in Islanded and Grid Connected Operations

Background: The Integration of non-conventional energy systems (NCES), like solar, wind, etc., into the grid with power electronic devices is adapted to meet the demand. Parallel connection of inverters (PCI) is an efficient method to boost power handling capacity, reliability, and system efficiency. However, the main drawback is the unequal power sharing among the inverters while using the conventional droop control technique (CDC). In addition, the circulating currents (CC) flow between these PCI, leading to common mode voltage (CMV), current waveform distortion, and reduction in the system's overall performance. Objectives: This work consists of a photovoltaic system (PVS) and battery energy storage system (BES) as the distributed generation (DG) unit to voltage source inverter (VSI) 1 and 2. The multi- objectives of the suggested work are (a) the equal power/load sharing among two inverters, (b) effective minimization of CC and the CMV, (c) maintaining constant DC-link (DCL) voltage during different solar irradiation and constant temperature, and (d) the reduction in total harmonic distortion (THD) of load current. Methods: A novel approach related to the enhanced droop control (EDC) method with an adaptive neuro-fuzzy hybrid controller (ANFHC) was suggested here to overcome the above issues. The performance analysis of the suggested technique was done in the Matlab/ Simulink platform with islanded and grid-connected modes for different loads. Results: A comparative analysis with the available methods like the proportional integral controller (PIC) and sliding mode controller (SMC) was carried out to exhibit the viability of the developed control technique. Conclusion: This study focused on the operation and control of a PCI with ANFHC in islanded and grid-connected modes to address issues such as uniform power sharing and reduction of CC and CMV.

Core design: Review & perspectives in Spain

In Core Fuel Management (ICFM) is an essential part of the operation of all commercial nuclear reactors. At the beginning of each fuel cycle (BOC), an optimal loading pattern is required to produce safe and economical operating conditions, such as uniform power distribution and a high degree of fuel burnup. These operating conditions are sought to achieve maximum useful life at minimum cost and the highest levels of safety, which leads to maximization of benefits. This article describes the work done by Spanish nuclear related organizations, which are currently involved in core design and core analyses from industrial, research and safety perspectives. In many instances, achieving enhanced accident tolerance would provide significant opportunities for outstanding research and improvements in operational cost benefits for the industry.

Maze-Based Scalable Wireless Power Transmission Experimental Arena for Freely Moving Small Animals Applications.

This paper presents an innovative T/Y-maze-based wireless power transmission (WPT) system designed to monitor spatial reference memory and learning behavior in freely moving rats. The system facilitates uninterrupted optical/electrical stimulation and neural recording experiments through the integration of wireless headstages or implants in T/Y maze setups. Utilizing an array of resonators covering the entire underneath of the mazes, the wireless platform ensures scalability with various configurations. The array is designed to ensure a natural localization mechanism to localize the Tx power toward the location of the Rx coil. The system is analyzed and modeled using ANSYS HFSS software to optimize design. The primary goal was to achieve uniform wireless power delivery throughout the mazes through a comparative study of different transmitter (Tx) array configurations, such as float, series, and parallel resonators. The calculated Specific Absorption Rate (SAR) in rat tissue model equals 1.7 W/kg at the power carrier frequency of 13.56 MHz. A prototype of the proposed maze-based WPT design, featuring 8 Tx resonators, a Tx coil and power amplifier, and a headstage power harvesting unit, is successfully implemented and its performance characterized for all three resonator configurations. The implemented T maze-based WPT system has a total length of 128 cm. In the overlapping Tx resonators configuration, a homogeneity of 94% is achieved for the measured power transfer efficiency at over 30%, while continuously delivering over 60 mW for series configuration.

Modular Linear Power Flow Model Against Large Fluctuations

The linear power flow model based on an empirical operating point is generally employed in power generation dispatch. However, with the increasing penetration of renewable energy sources (RESs) and frequent topology changes, the expansion of the operating region causes considerable modeling errors in the static linear power flow model. In this paper, the sources of linearization error are thoroughly analyzed, and a modular linear power flow modeling framework is proposed. It is found that the key features that affect the accuracy of linearization are the truncation error and its first derivative. This motivates us to cluster historical scenarios based on selected features. The key approach is to individually select a linear power flow model for power system operating conditions with similar linearization error features. This allows us to derive a refined linear power flow model for each cluster to avoid excessive linearization errors using a uniform linear power flow model. Numerical results for several IEEE and Polish test systems show that the linearization error of the proposed method is reduced up to 52.98% compared to current methods. The results demonstrate that the proposed method can use a small number of linearization segments to deal with topology changes.

Multi-resonator Wireless Inductive Power Link for Wearables on the 2D Surface and Implants in 3D Space of the Human Body.

This paper presents a novel resonance-based, adaptable, and flexible inductive wireless power transmission (WPT) link for powering implantable and wearable devices throughout the human body. The proposed design provides a comprehensive solution for wirelessly delivering power, sub-micro to hundreds of milliwatts, to deep-tissue implantable devices (3D space of human body) and surface-level wearable devices (2D surface of human skin) safely and seamlessly. The link comprises a belt-fitted transmitter (Belt-Tx) coil equipped with a power amplifier (PA) and a data demodulator unit, two resonator clusters (to cover upper-body and lower-body), and a receiver (Rx) unit that consists of Rx load and resonator coils, rectifier, microcontroller, and data modulator units for implementing a closed-loop power control (CLPC) mechanism. All coils are tuned at 13.56 MHz, Federal Communications Commission (FCC)-approved industrial, scientific, and medical (ISM) band. Novel customizable configurations of resonators in the clusters, parallel for implantable devices and cross-parallel for wearable devices and vertically oriented implants, ensure uniform power delivered to the load, PDL, enabling natural Tx power localization toward the Rx unit. The proposed design is modeled, simulated, and optimized using ANSYS HFSS software. The Specific Absorption Rate (SAR) is calculated under 1.5 W/kg, indicating the design's safety for the human body. The proposed link is implemented, and its performance is characterized. For both the parallel cluster (implant) and cross-parallel cluster (wearable) scenarios, the measured results indicate: 1) an upper-body PDL exceeding 350 mW with a Power Transfer Efficiency (PTE) reaching 25%, and 2) a lower-body PDL surpassing 360 mW with a PTE of up to 20%, while covering up to 92% of the human body.

A DVS-Enabled Distributed Digital LDO Providing Rapid Uniform Power Grid and Ripple Reduction Achieving 20.1-ps FOM in 28 nm CMOS

A DVS-Enabled Distributed Digital LDO Providing Rapid Uniform Power Grid and Ripple Reduction Achieving 20.1-ps FOM in 28 nm CMOS

Limitations of Bulk Diamond Sensors for Single-Cell Thermometry.

The present paper reports on a Finite Element Method (FEM) analysis of the experimental situation corresponding to the measurement of the temperature variation in a single cell plated on bulk diamond by means of optical techniques. Starting from previous experimental results, we have determined-in a uniform power density approximation and under steady-state conditions-the total heat power that has to be dissipated by a single cell plated on a glassy substrate in order to induce the typical maximum temperature increase ΔTglass=1 K. While keeping all of the other parameters constant, the glassy substrate has been replaced by a diamond plate. The FEM analysis shows that, in this case, the maximum temperature increase is expected at the diamond/cell interface and is as small as ΔTdiam=4.6×10-4 K. We have also calculated the typical decay time in the transient scenario, which resulted in τ≈ 250 μs. By comparing these results with the state-of-the-art sensitivity values, we prove that the potential advantages of a longer coherence time, better spectral properties, and the use of special field alignments do not justify the use of diamond substrates in their bulk form.

ОПТИМІЗАЦІЯ ГРАФІКІВ ЕЛЕКТРИЧНОГО НАВАНТАЖЕННЯ АГРЕГАТОРОМ У ЛОКАЛЬНИХ ЕЛЕКТРОЕНЕРГЕТИЧНИХ СИСТЕМАХ

The market operation of the electricity distribution system has gained significant expansion due to the growing use of renewable and distributed sources. This paper presents strategies for optimizing load schedules by aggregators of local systems. Optimization of load schedules is to minimize the total costs of the supplier to reduce the cost of electricity and lower prices for the consumer. In local systems, which include diesel generators, the main component that most affects the price per 1 kW is the consumption of primary fuel of diesel generators. The objective function proposed in this study minimizes the supplier's primary fuel consumption by optimally redistributing power to each generator. The basic load schedule and application of schedule optimization strategies were studied: load reduction, load transfer, increase of minimum loads, flexible load change. When using the optimal algorithm, the costs are 5-6% relative to the uniform power distribution. Ref. 8, fig. 4, table. Key words: local system, diesel-generator, load schedule, aggregator.

Validation of Pronghorn’s subchannel code using EBR-II shutdown heat removal tests: SHRT-17 and SHRT-45R

Pronghorn-Subchannel, referred to as Pronghorn-SC throughout this document, is a subchannel code within the Multiphysics Object-Oriented Simulation Environment (MOOSE) developed at the Idaho National Laboratory (INL). Pronghorn-SC was initially designed to model flows in water-cooled, square-lattice, bare subassemblies. Its capability has been extended to model flows in liquid-metal-cooled, triangular-lattice, wire-wrapped subassemblies. To ensure the accuracy of Pronghorn-SC in predicting the behavior of liquid sodium-cooled reactors, the code was validated by comparing calculations with experimental data, obtained from the experimental breeder reactor (EBR-II), Shutdown Heat Removal Tests (SHRT) 17 and 45R. The steady-state calculation at the beginning of the transients was validated using temperature measurements taken at different axial elevations in the instrumented subassembly XX09. The validation exercise was performed in successive stages. First, a comparison between the measured temperature profiles and standalone Pronghorn-SC simulations using a uniform pin power profile was made. The pin power profile was then refined using a Serpent-2 model of the reactor core. Finally, the radial temperature profile was further corrected considering the inter-assembly heat transfer. A Pronghorn Finite-Volume (FV) thermal hydraulic simulation of XX09 and its six neighboring subassemblies; calculated the heat flux on the inner duct surface of the XX09 subassembly to inform the Pronghorn-SC model. Last, a transient validation calculated the peak temperature evolution during the SHRT tests.

A selectable single-frequency erbium fiber laser with septuple-ring apparatus for narrow linewidth and uniform power output

A single-longitudinal-mode (SLM) erbium-doped fiber laser (EDFL) with septuple-ring is demonstrated to acquire tunable and stable wavelength output. The demonstrated septuple-ring design not only can result in mode-filter operation to diminish the dense longitudinal-mode oscillations, but also can reach sub-kHz linewidth. The presented fiber laser also can extend the tuning bandwidth from 1512.0 to 1572.0 nm based on C-band gain-medium and lead to a uniform power output range within 0.36 dB power fluctuation. Furthermore, the obtained output linewidth, output power (Pout), output stability and optical signal to noise ratio (OSNR) of the EDFL are also executed and discussed.

An attempt to find the optimal loading pattern of minor actinides in the PWR fuel rods

Three approaches of minor actinide (MA) loading in the fuel rods of a pressurized water reactor were examined. They comprised inserting MAs and fuel mixture in the center of duplex fuel rods, coating of MAs and fuel mixture in the outer layer of fuel rods and lastly, mixing MAs homogeneously with the entire fuel rod elements. AP1000 fuel assembly was chosen as the reference design. Two fuel types namely conventional UO2 and UTh MOX fuel were selected as the base fuel models for the study. Although shorter cycle length than the UO2 fuel design was achieved by the UTh fuel design, UTh fuel exhibited more favorable FTC and yielded a lower plutonium stockpile at the end of the fuel cycle. When MAs were added in the outer layer of fuel rods, it resulted in higher rate of transmutation, however it had an adverse impact on the fuel reactivity, discharge burnup and pin power distribution. On the contrary, when MAs were loaded in the central region, it led to incomplete incineration of MAs. Therefore, based on the satisfactory transmutation rate, MTC, most negative FTC and uniform pin power distribution, the homogenous MA loading strategy can be concluded as the optimal loading pattern for the AP1000 nuclear reactor.

Subchannel thermal–hydraulic analysis of a wire-wrapped 19-pin rod bundle in the NACIE-UP facility

Based on the experimental campaign performed on the NACIE-UP (NAtural Circulation Experiment-Upgraded) facility, the benchmark activity was proposed by ENEA to qualify and validate the numerical tools for the Heavy Liquid Metal (HLM) system. Xi’an Jiaotong University participated in the benchmark exercise of subchannel validation and the self-developed subchannel code YAOGUANG was applied to the thermal hydraulic analysis. The performed two tests with different power distributions on the Fuel Pin bundle Simulator (FPS) were simulated, characterized by transition from forced to natural circulation. The applicability of this code to the stable state and mass flow rate transient was evaluated by comparing the numerical outcomes with the experimental results. Then the effect of the non-uniform heating on the thermal field was analyzed. The results indicate that this subchannel code has good accuracy in simulating both steady state and transient conditions with uniform power distribution. For the non-uniform case, the subchannel calculations can capture the general trend of temperature distributions, with a larger simulation deviation observed. This discrepancy is mainly due to the limitations of existing models adopted because they didn’t consider the impacts of non-uniform conditions on the flow and heat transfer in rod bundles. Finally, the influence of non-uniform heating is mainly manifested as the increase of axial and radial temperature gradients and it helps to flatten the radial thermal field to some degree.

Multiphysics assessment of a PWR-type SMR core using Spherical Cermet fuel through a neutronic and thermohydraulic coupled study

In this paper, a multiphysics assessment of the performance of a PWR-type SMR core using Spherical Cermet Fuel is carried out, through a coupled neutronic-thermohydraulic study using Serpent and Ansys CFX codes. The most important results related to the core performance are compared with those obtained when TRISO fuel is used. Correlations (Cp, k) were developed as function of temperature for the fuel region, which are unique and specific for the fuel of this study. The results obtained show that the neutronic-thermohydraulic coupled calculation converges from the fourth iteration, with Keff being the convergence indicator that converges more slowly. An extended fuel cycle of 1448 days was achieved with a uniform power distribution. With this new core configuration, a lower production of plutonium isotopes was obtained. Temperatures below the safe operation limit were obtained in all the studied zones, as well as basic negative safety parameters such as fuel temperature and moderator temperature coefficients, and the full coolant void coefficient.

Development and Characterization of Hybrid, Temperature Sensing and Heating Yarns with Color Change.

A person's body temperature is an important indicator of their health status. A deviation of that temperature by just 2 °C already has or can lead to serious consequences, such as fever or hypothermia. Hence, the development of a temperature-sensing and heatable yarn is an important step toward enabling and improving the monitoring and regulation of a person's body temperature. This technology offers benefits to several industries, such as health care and sports. This paper focuses on the characterization and development of a hybrid yarn, which can measure and visualize temperature changes through a thermoresistive and thermochromic effect. Moreover, the yarn is able to serve as a flexible heating element by connecting to a power source. The structure of the yarn is designed in three layers. Each layer and component ensures the functionality and flexibility of the yarn and additional compatibility with further processing steps. A flexible stainless steel core was used as the heat-sensitive and heat-conducting material. The layer of polyester wrapped around the stainless steel yarn improves the wearing comfort and serves as substrate material for the thermochromic coating. The resulting hybrid yarn has a reproducible sensory function and changes its resistance by 0.15 Ω between 20 and 60 °C for a length of 30 cm. In addition, the yarn has a uniform and reproducible heating power, so that temperature steps can be achieved at a defined length by selecting certain voltages. The thermochromic color change is clearly visible between 28 and 29 °C. Due to its textile structure, the hybrid sensory and actuating yarn can easily be incorporated into a woven fabric or into a textile by means of joining technology sewing.

Experimental study on coupled quenching behavior in a dual-cooled annular rod channel

In this paper, a bottom reflooding experiment was performed in a single annular rod channel to investigate the coupled quench characteristics of the dual-cooled annular fuel. An indirect-heated annular rod with the axial uniform power shape was used. The asymmetric quench front propagation between the external and internal sides of the annular rod was observed. The internal cladding was quenched earlier than the external cladding, owing to heat accumulation in cylindrical shell and the blockage of the vapor flow by the grid spacers in external channel. A unique “secondary quenching” phenomenon was observed at the internal side of annular rod due to the radial heat conduction. The effects of reflooding velocity, inlet subcooling, initial cladding temperature and heating power on quenching behavior were also studied. The present study can contribute to the understanding of the coupled quenching characteristics of dual-cooled annular fuel and obtains valid data for the development of reflooding models and the validation of thermal hydraulics codes of annular fuel.

Inter-Numerology Interference in Mixed Numerology OFDM Systems in Time-Varying Fading Channels With Phase Noise

Mixed numerology has been adopted in the orthogonal frequency division multiplexing-based physical layer of 5G new radio (NR) to serve diverse use cases and services. Since the subcarriers of different numerologies have different bandwidths and symbol durations, they interfere with each other despite being centered at different frequencies. We analyze the inter-numerology interference (INI) encountered by these systems in wideband time-varying channels in the presence of phase noise. We derive novel expressions for the fading-averaged INI power at each subcarrier as a function of the channel’s power delay profile. These lead to insightful, tight bounds for the bandwidth-averaged INI power, which bring out the combined impact of Doppler spread and phase noise. Our comprehensive approach applies to the entire family of numerologies of 5G NR, and accounts for partial subcarrier loading, guard bands, and non-line-of-sight and line-of-sight channels. Our results show that INI affects high-rate modulation and coding schemes (MCSs). To mitigate its impact, we propose a novel statistical square root power allocation scheme that exploits the variation in the average INI powers across the subcarriers. It achieves a lower block error rate than uniform power allocation, which is used in 5G NR.

Neutronic and thermal analysis of heat pipe cooled graphite moderated micro reactor

Heat pipe micro reactors are drawing a lot of interest lately due to their distinct features, including the elimination of moving parts required for transferring the heat, as they do so passively through heat pipes, combined with the ability of such reactors to provide energy to remote locations. This present study introduces a proposed design for heat pipe cooled graphite moderated micro reactor suitable for remote locations and space applications. The main requirements of the design include long core lifetime, two shutdown mechanisms, uniform power distribution, and strong negative temperature coefficient. Neutronic calculations were performed using MCNP 6.2 code. Criticality analysis demonstrated the ability of both control devices incorporated in the design to independently control and shutdown the reactor. Calculations of the flux and power distribution showed that, for a thermal power of 0.25 MW, the maximum flux at mid-plane of the reactor is in the order of 1012n/(cm2·s), while radial and axial power peaking factors were found to be 1.2 and 1.13, respectively. The results also showed that the reactor has an overall negative temperature coefficient. Additionally, burnup calculations were carried out to calculate the core lifetime which was estimated to be more than 70 years. A preliminary steady-state thermal analysis was conducted for the reactor using ANSYS FLUENT, assuming 1/12th symmetry. The obtained temperature distribution of the reactor showed that the operating temperatures are within the accepted limits where the highest temperature reached in the fuel was 1074 K. Furthermore, soft coupling of MCNP and ANSYS FLUENT was conducted through an iterative process of performing neutronic and thermal simulation using updated results for the temperatures and power distributions in each iteration.

Evaluating the influence of radial power heterogeneity of fuel rod on its temperature in an accelerator driven subcritical system

Abstract The radial non-uniformity of an ADS fuel rod power density on the peak plane is as high as 10.46 %, which is derived from the reactor physics calculations. In order to investigate the influence of the above-mentioned radial power inhomogeneity on the fuel temperature distribution, this paper constructs a set of two-dimensional comparison examples, where one example uses a uniform heat source and another uses a non-uniform heat source distribution, with taking the fuel segment and its corresponding cladding segment in the region where the peak plane is located as the research object. The finite element software COMSOL is used to conduct the heat transfer analysis. The results of the study show that the fuel temperature under radial non-uniform power distribution is almost the same as that under uniform power. Therefore, this radial non-uniformity can be completely ignored when the research object of temperature is considered. The quantitative calculation carried out in this research can provide certain data support for the engineering research of accelerator driven subcritical system, and can also provide certain guidance for the performance analysis of such fuel elements.

Steady-state and transient thermal–hydraulic analysis for high temperature heat pipe cooled reactors

Heat pipe-cooled reactors (HPR) have become increasingly popular in recent years due to their good thermal conductivity and adaptability. The steady-state and transient characteristics of the high-temperature alkali heat pipe, which is the primary component of the HPR, are crucial for ensuring the safe operation of the reactor. In this study, a CFD model was established to evaluate the steady-state and transient characteristics of heat pipes. Heat pipes using potassium (K), sodium (Na), and lithium (Li) as a medium were examined and the effect of heating power was analyzed under steady-state conditions. The results indicated that Li had the highest operating temperature, followed by Na and K. However, the thermal resistance was the lowest for Li and highest for K. The wall temperature showed a gradual decrease. As the heating power increased from 3 kW to 7 kW, the vapor temperature increased from 1005 K to 1109 K. The axial temperature difference was only 5 K, indicating that the heat pipe had good isothermal properties. Moreover, the startup method and heat pipe failure were analyzed under transient conditions. Compared to the uniform power rise, the phased power start method ensured the heat pipe started up successfully. Case1 has the shortest startup time, with a successful startup time of 1800 s. Single heat pipe failure and fuel assembly failure resulted in local temperature increases, but away from the failure areas were rarely affected. Failure in startup is 63 K higher than steady-state failure, which deserves more attention. Moreover, it is important to note that failures during startup resulted in a temperature increase of 63 K higher than steady-state failures, which warrants further investigation and attention.

Multi-Lens Array (MLA)-Assisted Power- Modulated Photothermal Therapy for Enhanced Cancer Treatment

Photothermal therapy (PTT) has been used as a non-invasive and effective anti-tumor treatment by localizing optical energy in the tissue. The aim of the current study was to investigate the efficacy and safety of PTT against tumor by applying multi-lens arrays (MLA) for having uniform micro-beam distributions and power modulation (MD) for sustaining constant treatment temperature in the tissue. A 1064 nm laser system delivered the equivalent energy (270 J) through two different manners (flat optical fiber; Flat and MLA) to a target under three different irradiation conditions: 1.5 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> for 180 s, 3 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> for 90 s and 3 W/cm2 for 60 s followed by 1.5 W/cm2 for 60 s (MD). In vivo tests demonstrated that MLA was able to expand a distribution of constant temperature (up to 40%) and the extent of thermal coagulation (up to two-fold) in the tumor than Flat. Irrespective of delivery method, MD maintained a constant temperature (around 60°C) for 60 s, compared to fixed power, resulting in insignificant tumor recurrence ten days after treatment. MLA-assisted PTT with MD could enhance a therapeutic capacity against the tumor tissue by covering a wide treatment area with larger coagulative necrosis and less thermal injury