Load Capacity Of System Research Articles

A recompression supercritical CO2 cycle using heat source storage to achieve low-frequency reactor regulation: Analysis and optimization of load capacity under safe compressor operation

This study focuses on proposing a heat source storage mode for the indirect recompression supercritical CO2 cycle (RSCC) coupled with a sodium-cooled fast reactor, aiming to achieve low-frequency regulation of the reactor and enhance the load capacity of system. A deep neural network-based turbomachinery performance prediction approach is employed to assess the system's part-load and overload performance under several typical control strategies. The turbine inlet temperature of the system under all control strategies except the intermediate heat exchanger (IHX) bypass rises with decreasing load. The system's part-load performance is positively correlated with its corresponding overload power. The findings reveal that the adjustable load ranges of the heat source storage tanks under inventory, turbine bypass, turbine throttle, and IHX bypass controls are 10%–156.10%, 10%–156.10%, 30%–147.30%, and 10%–146.88%, respectively, along with the safe compressor operation. As the near-choke operation of the compressor limits the rise in overload power, a turbine fitted with variable inlet guide vanes is tried. The optimization results demonstrate that the largest overload power of the system can reach 161.18 % without reducing the thermal efficiency. This study provides a heuristic insight into the variable load operation for indirect nuclear-powered Brayton cycles under low-frequency reactor regulation.

Application of Gray Expansion Model in Energy Economic Analysis and Load Forecasting

Objective and effective prediction of energy consumption can not only optimize the energy consumption structure, but also provide important information for the government to formulate energy conservation and emission reduction measures. With the development of new energy sources and changes in the global energy consumption structure, historical energy data that are too old may no longer be reliable for forecasting, which leads to a decrease in the amount of information on energy, and the gray theory, which is applicable to “poor information”, has gained attention. Firstly, the optimization of energy economic objectives and transformation path methods at this stage is clarified; then, the DEA-Malmqusit model is used to improve the shortcomings of the traditional model that can only compare different cross-sections at the same time node, and to evaluate and analyze the full-factor multi-indicators of energy enterprises in terms of technological empowerment, environmental dynamics, and economic output efficiency; finally, the LEAPS-based energy system consumption and load capacity prediction model. The results show that the traditional algorithm is not accurate enough and has some deviation when the energy raw data fluctuates a lot. The algorithm proposed in this paper still gives a better prediction, predicting a city’s carbon emission to be 65,240,100 tons in 2024, with a 3.6% increase in energy output year by year.

PSII-14 Chemical Composition of Tropical Forage Fertilized with Different Sources of Nitrogen Fertilizers

Abstract Nitrogen fertilization can improve the chemical composition of tropical forages, as nitrogen is required at all stages of plant development. The aim of this study was to verify the chemical composition of Urochloa brizantha cv. marandu fertilized with different sources of nitrogen fertilizers from the following treatments: without nitrogen fertilization (CO), fertilization with urea (UR), fertilization with ammonium nitrate (NI) and fertilization with ammonium sulfate (SA). The study was carried out from December 2021 to April 2022, in the cerrado biome of Brazil at the FCAV/UNESP Forage Sector, Jaboticabal Campus, during the rearing phase of Nelore cattle, non-castrated males kept on pasture, managed in a continuous stocking system and variable load capacity. In treatments with fertilization, 150 kg of N· ha-1 were applied, divided into 3 applications. The design used was in randomized blocks (DBC). The evaluation of the chemical composition of the forage was carried out from collections every 28 days of samples of the fraction of the forage consumed by the animals through the hand-plucking method. The samples were dried at 55ºC for 72 hours and ground in a Willey mill, with a 1 mm mesh sieve. The chemical composition of the forage was estimated by spectroscopy in the near infrared light region, NIRS (Near Infrared Spectrometer), using a modular FT-NIR spectrometer. The data obtained were submitted to ANOVA and Tukey's test (P ≤ 0.05), using the statistical program R, version 3.4.4. Nitrogen fertilization significantly increased the organic matter content of the forage (P = 0.001). The organic matter content of the non-fertilized treatment was 91.97%, while the average of the fertilized treatments was 92.22%. The percentage of crude protein in the forage also showed a significant difference (P < 0.001) between the non-fertilized treatment, which had an average of 10.64%, and the fertilized treatments, which had an average of 17.75%. The neutral detergent fiber and acid detergent fiber components also differed from the application of nitrogen fertilizer (P < 0.001) but did not differ between the types of fertilizers. The neutral detergent fiber content was significantly different (P < 0.001) between the non-fertilized treatment (59.21%) and the fertilized treatments (54.30%). The observed data for acid detergent fiber were 31.46% for the treatment without the use of fertilizers and 30.24% for the treatments with the use of fertilizers. Non-fibrous carbohydrates and liguinin components were also analyzed, but showed no difference between treatments, P = 0.078 and P = 0.209, respectively. This study confirms that the chemical composition of Urochloa brizantha cv. Marandu can be significantly improved through the application of nitrogen fertilizers. However, our results showed no significant difference between the types of fertilizers tested.

Interconnection Study in Utilizing of Solar Energy for 150 MW Photovoltaic Power Generation through 150 kV Transmission Line

The interconnection of utility-scale photovoltaic (PV) power plants with the electric grid is a crucial factor that requires comprehensive analysis and assessment. The focus of this research article is on a specific photovoltaic (PV) power plant that is planned for construction in the X Power System located in Indonesia which has 150 MW capacity which has intermittent behavior, experiencing fluctuations in power generation based on the availability of sunlight and the cloud movement. The objective of this paper is to explore the feasibility, technical prerequisites, and potential solutions for the successful integration of the PV power plant into the existing power system. Multiple investigations will be carried out, which is Load Flow, Short-Circuit, and Transient Stability analyses, with the aim of assessing the consequences of linking the PV power plant to the existing power system. Consequently, it is vital to model the X power system conditions prior to the interconnection process. Moreover, modeling an intermittent PV power plant necessitates different approaches compared to conventional power plants. According to the research findings from load flow analysis, the voltage levels near the interconnection point, both prior to and after linking the PV Power Plant, remain within permissible bounds of +5% and -10%. Furthermore, there are no constraints on the load capacity of the transmission lines and Interbus Transformers (IBT) either prior to or following the integration of the PV Power Plant. The short-circuit current around the point of interconnection experiences a marginal increase, and it is advisable to employ circuit breakers (CB) rated at 40 kA for both the PV Power Plant and the switching station. Furthermore, the power system exhibits resilience in preserving its stability, even in scenarios involving abrupt power loss or intermittent generation from the PV Power Plant. These situations can result from unexpected outages or variations in solar radiation. The interconnection of the 150 MW PV Power Plant can be implemented without significant adverse effects on the system's voltage, loading capacity, and stability.

Modeling the load capacity of frequency-tracked rotary ultrasonic machining system

Rotary ultrasonic machining (RUM) is a superior processing method for difficult-to-cut materials. It employs a large enough ultrasonic amplitude of the tool to enable its unique intermittent cutting mechanics. The critical cutting force is a vital performance indicator to characterize the load capacity for the RUM system. If the cutting force exceeds a critical value, the ultrasonic amplitude of the tool will be restrained as a minimal value due to the deviation of resonant frequency, resulting in the performance loss of RUM. However, the current understanding of critical cutting force only applies to the RUM system without a frequency-tracking module. This study tries to fill the knowledge gap regarding the load capacity of the frequency-tracked RUM system. First, the dependency of actual ultrasonic amplitude on the cutting force is modeled based on the RUM system's input-output relation that uses a frequency-tracking module. Then, the critical cutting force is derived by inverse solving the above model Afterward, we propose a measurement method of the actual ultrasonic amplitude under load by observing the tool vibration trace on the machined surface using a diamond indenter. Moreover, an easy-to-operate experimental method to measure the critical cutting force is developed. Finally, serial load experiments of the RUM system under different driving voltages are performed. The experimental results verified the models of actual ultrasonic amplitude and the critical cutting force. Based on the model, the influences of the electrical and mechanical design of the frequency-tracked RUM system on the critical cutting force are analyzed.

Load Capacity of Cylindrical Self-Braking Gear System

Load Capacity of Cylindrical Self-Braking Gear System

Seismic performance of an assembled self-centering buckling-restrained brace and its application in arch bridge structures

Aiming to reduce residual deformation, herein, we propose the design concept of a self-centering buckling-restrained brace (SC-BRB) applied to the structural fuse of arch bridge structures. First, a novel assembled SC-BRB with combined disc springs is proposed. Notably, the hysteretic curve characteristics can be effectively controlled by the ratio of the BRB system load capacity to the SC system preload. The construction and operating mechanism of the novel SC-BRB are described, and a theoretical hysteretic model under cyclic loading is derived. Five SC-BRB specimens with different combinations are designed and fabricated. Through quasi-static tests, the characteristics including residual deformation and hysteretic energy dissipation are analyzed and compared to explore the self-centering effect and damage mode. The test results reveal that the hysteresis curve of the assembled SC-BRB is characterized by an apparent flag-type form and stable hysteretic performance. The combined disc spring significantly reduces the residual deformation of the brace, resulting in an apparent self-centering effect. The theoretical hysteretic model proposed in this paper agrees well with the test results. Finally, a comparative analysis is conducted on the seismic performance of a concrete filled steel-tube (CFST) arch bridge structure with three types of lateral braces: SC-BRB, BRB, and an ordinary brace. The OpenSees analysis results demonstrate that the CFST with the SC-BRB demonstrates better performance in terms of the displacement response and residual deformation compared with the other two CFSTs.

Cascade Model Predictive Current Control for Five-Phase Permanent Magnet Synchronous Motor

As to the model predictive control for five-phase permanent magnet synchronous motor (PMSM), it is difficult to ensure the optimal control performance by using calculation method to obtain the weighting factor. To solve this problem, a cascade model predictive current control based on the idea of sequential model predictive control is proposed for five-phase PMSM for the first time. Firstly, the principle of selecting the optimal voltage vector by the proposed method is analyzed in detail. Then, combined with the characteristics of five-phase PMSM, the control priority of controlled variables is set for designing two cost function schemes without weight factor. The maximum torque scheme can generate a trapezoidal stator voltage, improving the DC bus voltage utilization rate and the system loading capacity. The minimum harmonic current scheme can reduce the harmonic of stator current, obtaining small system noise and vibration. The experimental results indicate that the proposed method can ensure the optimality of the voltage vector applied. Therefore, the five-phase PMSM obtains good performance under different working operation, such as small torque ripple, fast dynamic response, and small harmonic current.

Performance of Inclined Skirt Footing: Numerical Analysis

The skirt footings are considered as alternate to enhance the bearing capacity of shallow foundation on sandy soil as an alternate of deep foundation. The experimental data of paper titled “Performance of skirt strip footing subjected to eccentric inclined load was consider as base for validation and other parameters of material for numerical investigation for different conditions. Numerical analysis was conducted to determine the behavior of two-sided skirt footing on eccentric loading with different angle and projections provided to skirt. The study reveals good impact of skirt angle and skirt projection lengths on load capacity of footing system

Collection Method of Arbitrary Laser Echo Based on STM32

When LIDAR measures the water depth, in most cases the echo signal is more complex, with more backscattering, and it is difficult to observe different parts of the waveform separately, especially the underwater echo signal. Therefore, this paper uses an STM32 controller to design a signal generator to send out pulse signals, which act on the detection device PMT in the LIDAR detection system to control the start and stop of the PMT receiving channel. By adjusting the frequency, duty cycle, and other parameters of this signal generator, the arbitrary part of the waveform can be collected, and the waveform is not disturbed. Using the STM32 instead of a traditional signal generator can reduce system power consumption and load capacity.

Improvement of Static Voltage Stability of 16-Bus Bali System by Optimal Placement of SVC

In a power system, the reactive power imbalance is related to the stability of the static voltage because the injection of reactive power that the bus receives from the system determines the bus's capability in the system. Rapid increases in real and reactive power losses occur as the system approaches the voltage drop point or the maximum load point. It is necessary to support local and adequate reactive power to avoid system leading to be voltage collapse. This study analyzes the improvement of the margin of static voltage stability using one type of modern control equipment of shunt flexible AC transmission system (FACTS), namely the static var compensator (SVC). The controller's representations are used in the continuation power flow (CPF) process to study static voltage stability. The proposed method's effectiveness has been investigated using a practical test system, namely the Bali 16-bus system, to increase the system loading capacity. The simulation was carried out by installing a modern controller in the best location, namely on bus 07 ASARI; an increase in system margin loading closed to 2% compared to the base case condition, namely λmax = 1,879 p.u with the voltage profile not changing significantly.

Planning Flexibility With Non-Deferrable Loads Considering Distribution Grid Limitations

Non-deferrable loads equipped with distributed energy resources, such as solar photovoltaic generation and energy storage, can offer a wide range of benefits to the power system, including load leveling, hedging against forecast uncertainty, and ancillary services. This paper presents a techno-economic approach to optimally equip a flexible energy resource, namely a battery energy storage system (BESS), with non-deferrable loads for capacity enhancement of a distribution grid. The proposed approach is generic in applicability, and includes two different optimization mathematical models. The first model quantifies the needed flexibility with non-deferrable loads, based on a consideration of distribution grid limitations, while the second model determines the optimal flexibility amount associated with non-deferrable loads considering investor profitability. Thereafter, a distribution operations model is developed to evaluate the impact of non-deferrable loads, equipped with an optimal size of BESS, on the distribution system loading capacity. An example of non-deferrable loads considered in this paper is that of the rapid charging loads of plug-in electric vehicles (PEVs) that cannot be controlled or shifted due to the short stay of PEVs at a charging facility. Hence, a probabilistic model for PEV rapid charging loads is first developed. Case studies and simulation findings, considering a 32-bus distribution system, demonstrate that the proposed approach helps reduces the impact of non-deferrable loads on a distribution system and enhances the system power margin, which defers the need for system upgrades.

Influence of cluster shaped defects on fracture process of fiber bundle

Defects that exist inside composites have an important effect on the tensile fracture properties of composites. The fiber bundle model is a theoretical model commonly used to study the tensile fracture properties of disorder materials. Existing work on fiber bundle models with single fiber defects shows that after single fiber defects are introduced into the fiber bundle model, the defects have a significant effect on the tensile fracture properties of the model. Since there are more complex microscopic defect structures in actual materials, such as voids, gaps, impurities, dislocations, micro-cracks, etc, it is necessary to build a multi-size defect model. In order to study the defects of different sizes and damage degrees existing in actual materials, the spatial size of the defect, the degree of defect and the distribution of fiber damage levels within the defect and other influencing factors are introduced to construct an extended fiber bundle model with cluster shaped defects. For the model, it is first assumed that the degree of defect of the fiber inside each cluster decays linearly from the center to the outside in two spatial attenuation forms: exponential decay and constant degree of defect. In the fiber bundle model of this cluster-shaped defect, the two most important factors are the number of defects <i>α</i> and the upper limit of defect size <i>β</i>. The numerical simulation method is used to analyze the influence of the number of defects, the upper limit of defect size, and spatial distribution of degree of defective fibers inside defect on the macroscopic mechanical properties and statistical properties of fracture when the model is subjected to quasi-static load borne under the nearest neighbor stress redistribution. Through the simulation analysis, it is found that owing to the overlapping competition mechanism of the defect spatial distribution, when the upper limit <i>β</i> of the defect size is large, the influence of the number of defects on the system load capacity trends to saturation. Since the defect degree of the defect center fiber is proportional to the defect size, with the upper limit <i>β</i> of the defect size increasing, its influence on the load capacity of the model becomes more and more significant. When large size defects exist, even if the number of defects is small, the load bearing performance of the material will be significantly reduced. The spatial distribution function of the damage degree of fiber inside the defect has no substantial influence on the above rules, and only changes the specific value of each fracture property. The simulation analysis results in this paper have certain theoretical significance in improving the mechanical properties of composite materials.

Experimental Study on Load Carrying Capacity Enhancement of System Supports Considering Full Installation of Bracing Members

This study investigated the ultimate load capacity of assembled system supports by comparing cases with and without bracing members. Supports used as temporary structures are essential to resist the concrete casting load. Current trends encourage the use of system supports to prevent the collapse of supports, which occur frequently. Studies regarding the ultimate behavior of system supports in Korea are fewer than those in other countries. Existing studies have only focused on the behavior of unit members, such as vertical members. However, studies that focused on unit vertical members under axial loading reported difficulty in predicting the ultimate behavior of assembled system supports. Furthermore, the ultimate strength of the system support can be decreased significantly in cases without a bracing member, which occur frequently at actual sites. Therefore, the ultimate behavior of the system support considering actual construction site conditions was investigated through experimental tests, focusing on whether bracing members were installed. Experimental results showed that the load-carrying capacity of a three-story system support without a bracing member was 38.4% that of the system support with full bracing members. In addition, the load-carrying capacity of the three-story system support without bracing members decreased by 41.2% compared with that of a two-story system support without bracing members. This indicates that the installation of bracing members is essential for increasing the ultimate load capacity of system supports, and the number of stories of system supports should be considered to determine their ultimate strength.

Photovoltaic Generation Integration with Radial Feeders Using GA and GIS

The electric power generated from different electricity sources are not used efficiently by end users in the world. This is due to the loss of power supplied in the case of electricity transmission and distribution to residential, commercial, and industrial loads. Even if the loss of power in the power system cannot be avoided 100%, it should be reduced to the minimum optimal value. The loss of power in the radial feeders can be minimized using an optimally allocated photovoltaic (PV) generation system by considering the information of geography, solar irradiance of the site, and space availability, which should not have shadow from large buildings and trees. The PV generation system eliminates the problem of power demand by enhancing the capacity of the power network as well as by reducing the depletion and consumption of fossil fuel resources. To reduce power loss and improve system loading capacity for demand response, the integration and finding the optimal place of photovoltaic generation take high concern from power system operators and technicians. The optimal allocation of PV has been done using the Genetic Algorithm (GA) for optimization of a multiobjective function with different constraints. The main objective of this paper is to minimize the power loss of the radial distribution networks by maintaining the phase voltage of the load in balance and improving the drop in voltage along the phase. So, GA is used to determine the best location and capacity of PV generation that can reduce the loss of power in the system. The IEEE-33 bus system is used to test the proposed method. Generally, using the GA and GIS methods results in a high accuracy for optimal placement of PV generation in the IEEE-33 bus radial feeder and enables to reduce the loss of power during transmission and distribution by maintaining the power quality for consumers.

Experimental and Numerical Study on the Effect of Heel Plate Length and Thickness on the Structural Integrity of Cold-formed Steel Roof Trusses

Cold-Formed Steel (CFS) is widely used as secondary framing material. Nowadays, the research of CFS as a primary steel roof truss system became more favoured. Therefore, it is very important to understand the behaviour of CFS roof trusses due to the uncertainty of the configuration of CFS roof trusses can affect its structural integrity. The objective of this research is to investigate the effect of heel plate length and thickness to the ultimate load capacity of CFS roof truss system. Nine different lengths and thicknesses of heel plate specimens were fabricated and subjected to concentrated loads until failure. The highest ultimate capacity for the experiment was 28 kN. Local buckling of top chords adjacent to the heel plate was the primary failure mode for all the heel plate. The results showed that the increment of the length and thickness of the heel plate had slightly increased the ultimate capacity, but decrease the deflection. The behaviour of the numerical results showed a good agreement with the experimental results. Numerical load capacity was higher than experimental load by an average ratio of 1.12. The behaviour of the bottom chord for both results was different after the load reached 20 kN.

PENINGKATAN STABILITAS TEGANGAN STATIS DENGAN PENEMPATAN OPTIMAL STATCOM PADA SISTEM KELISTRIKAN BALI 16-BUS

Voltage instability is mainly related to reactive power imbalances. The durability of the bus in the power system depends on the reactive power support that the bus can receive from the system. Since the system approaches the maximum loading point (MLP) or the voltage breakdown point, the real and reactive power loss increases rapidly. Therefore, the reactive carrying capacity must be local and adequate. This research studies the effect of using one type of Flexible AC Transmission System (FACTS), Static Synchronous Compensator (STATCOM), on increasing the Static Voltage Stability margin. STATCOM AC and DC representations used in the Continuation Power Flow (CPF) process in static voltage stability studies. The effectiveness of the proposed method has been practically simulated on the Bali 16-bus electrical system to investigate the system loading capacity increase. From simulations carried out with installing the modern controller in the best location, an increase in the endurance margin of the power system can obtain significantly.

The Effect of Energy-Supply and Performance Indicators on the Performance of Traction-Resource Management Centers

This paper presents the results of a study of the effect of the characteristics of the traction power-supply system on the indicator of the energy supply of electric rolling stock. The power-supply indicator of the electric locomotive is described as a function of the indicators of the load capacity of a traction power system and operational indicators of the transportation process: the mass of trains, speed, headway, and a number of others. Statistical methods and results of the evaluation of the effectiveness of the use of traction resources for the territorial branch of the operating domain on the basis of rolling stock quality indicators have been presented. The organizational structure and model of the management of traction resources taking into account the inclusion of the functions of the relationship with the territorial directorates of Transenergo have been presented.

Analysis of a passive scissor-like structure isolator with quasi-zero stiffness for a seating system vibration-isolation application

It is widely known that vibration is a mechanical motion phenomenon where a mass point oscillates around an equilibrium point. Vibrations are a source of discomfort and are extremely harmful to vehicle drivers and passengers. The motivations of this research are to develop an innovative vehicle seating suspension system to isolate vibrations transmitted to vehicle drivers and passengers and to improve ride comfort to ensure that their health is not negatively impacted and to improve the working efficiency of the driver. An innovative design of a passive multi-degree-of-freedom vibration isolator is presented in a truck seat suspension system where a Stewart platform configuration with a six-degree-of-freedom (6-DOF) isolation system is used rather than the traditional Stewart platform. A scissor-like structure (SLS) is used as one of the supporting legs to provide a nonlinear system with quasi-zero stiffness (QZS). Vibration is effectively attenuated without a loss of the system's load capacity. The effects of structural parameters in the proposed system are studied to determine how to adjust the parameters to achieve better vibration-isolation performance. The results reveal that a SLS supporting leg with a small assembly angle, more layers, a shorter link length and less spring stiffness has led to better vibration isolation and higher system stability than the conventional baseline supporting structure.

Analysis of a passive scissor-like structure isolator with quasi-zero stiffness for a seating system vibration-isolation application

It is widely known that vibration is a mechanical motion phenomenon where a mass point oscillates around an equilibrium point. Vibrations are a source of discomfort and are extremely harmful to vehicle drivers and passengers. The motivations of this research are to develop an innovative vehicle seating suspension system to isolate vibrations transmitted to vehicle drivers and passengers and to improve ride comfort to ensure that their health is not negatively impacted and to improve the working efficiency of the driver. An innovative design of a passive multi-degree-of-freedom vibration isolator is presented in a truck seat suspension system where a Stewart platform configuration with a six-degree-of-freedom (6-DOF) isolation system is used rather than the traditional Stewart platform. A scissor-like structure (SLS) is used as one of the supporting legs to provide a nonlinear system with quasi-zero stiffness (QZS). Vibration is effectively attenuated without a loss of the system's load capacity. The effects of structural parameters in the proposed system are studied to determine how to adjust the parameters to achieve better vibration-isolation performance. The results reveal that a SLS supporting leg with a small assembly angle, more layers, a shorter link length and less spring stiffness has led to better vibration isolation and higher system stability than the conventional baseline supporting structure.