Effect Of Load Variation Research Articles

Effect of Load Variation and Fault Resistance on the Operation Time of IDMT Overcurrent Relay

Fault can occur in power system due to many factors such as lightning, tree or crane encroachment, animal intervention, human error etc. Each fault occurrence has its own fault resistance value, and this value is unknown to the protection relay used to the protect the circuit. Besides that, the connected load in power system is dynamic where the value is changing over time. It is very important for the protection relay to be as reliable as it can so that the fault can be isolated as soon as possible when a fault occur. This paper study the effect of fault resistance value and load variation on IDMT overcurrent relay operation time. This relay is used to protect the line from fault occurrence where the higher the fault current, the faster the operation time will be. MATLAB Simulink has been used to model the transmission line, source, connected load and IDMT overcurrent relay. Faults simulations were conducted for various fault resistance and load values and the effects on relay operation time have been analysed. From the results, it was found that, the higher the fault resistance, the higher the operation time while the higher the value of connected load at the end of the line, the faster the relay operation time.

Impact of Chaos on MOSFET Thermal Stress and Lifetime

The reliability of power electronic switching components is of great concern for many researchers. For their usage in many mission profiles, it is crucial for them to perform for the duration of their intended lifetime; however, they can fail because of thermal stress. Thus, it is essential to analyze their thermal performance. Non-linear switching action, bifurcation and chaotic events may occur in DC-DC power converters. Consequently, they show different behaviors when their parameters change. However, this is an opportunity to study these bifurcation phenomena and the existence of chaos, e.g., in boost converters, on their performance as the effects of load variations (mission profiles) on the system’s behavior. These variations generate many non-linear phenomena such as periodic behavior, repeated period-doubling bifurcations and chaos in the MOSFET drain-source current. Thus, we propose, for the first time, an analysis of the influence of chaos on the junction temperature. First of all, this paper provides a step-by-step procedure to establish an electrothermal model of a C2M0080120D MOSFET with integrated power loss. Then, the junction temperature is estimated by computing the power losses and a thermal impedance model of the switch. Additionally, this model is used to investigate the bifurcation and chaotic behavior of the MOSFET junction temperature. The paper contributes by providing a mathematical model to calculate several coefficients based on experimental data and thermal oscillations. Estimation of the number of cycles to failure is given by the Coffin–Manson equation, while temperature cycles are counted using the rainflow counting algorithm. Further, the accumulated damage results are calculated using the Miner’s model. Finally, a comparison is made between the damage accumulated during different mission profiles: significant degradation of the MOSFET’s lifetime is pointed out for chaotic currents compared to periodic ones.

Impedance Circle Modeling and Dynamic Characteristics Analysis of Contactless Energy Transfer System Under Load Variations in Rotary Ultrasonic Machining

In rotary ultrasonic machining, contactless energy transfer (CET) is developed to transmit energy to the transducer at the series resonant frequency or resonant frequency of the transducer. Specifically, during energy transmission, variations in working conditions such as variable axial forces will change the load of the transducer and introduce undesired dynamic effects into the contactless energy transfer system (CETS). In order to explore the connections between these variations and the working performance more directly and theoretically, a new theoretical model—CETS impedance circle is proposed in this paper to reflect the CETS dynamic characteristics, including the CETS frequency characteristics and the relationships between CETS transfer performances at different frequencies under load variations. With the developed theoretical model, the effect of load variations on the trends of CETS impedance circle is investigated. Moreover, based on the impedance circle and its trends, the CETS frequency characteristics, the effect of primary series compensation, and a comparison of the transfer performances at the two working frequencies are theoretically studied. Finally, the CETS impedance circle theories are experimentally verified, and the experimental results are consistent with the analysis of the theoretical model.

Performance Evaluation and Dynamic Characteristics of a Self-Excited Induction Generator for Pico Hydro Power Plants

The dynamic performance of an isolated three-phase squirrel cage self-excited induction generator (SEIG) in a Pico Hydro Power Plant (PHPP) is examined in this work. The investigation is carried out with the help of MATLAB/Simulink for mathematical modeling and simulation of the proposed system under various operational situations. The SEIG model, which was created using the steady-state equivalent circuit approach, included the electrical, magnetic, and mechanical components of the SEIG and PHPP. The dynamic behavior of the SEIG is explored under a variety of operating situations. The effects of load variations, speed fluctuations, and other disturbances on the voltage and frequency of the generator are examined. The experiment results were used to validate the simulation results. This research has implications for the design and optimization of PHPP using SEIGs.

Multifaceted Functionalities of Bridge-Type DC Reactor Fault Current Limiters: An Experimentally Validated Investigation

With the ongoing expansion and interconnection of electrical power systems, alongside the rapid proliferation of renewable distributed generations (DGs), the short-circuit extent in the power grid is experiencing a significant rise. Fault current limiters (FCLs) have been introduced in an effort to address this issue, ensuring the robustness and sustainability of expensive power system components when confronted with short-circuit faults. Among the various types of FCLs, bridge-type DC reactor fault current limiters (BDCR-FCLs) have emerged as one of the most promising options. While BDCR-FCLs have shown excellent properties in limiting harmful short-circuit currents, they are also advantageous in other respects. This paper investigates the supplementary functionalities of BDCR-FCLs as a multifaceted device towards the enhancement of the quality of supplied energy in terms of total harmonic distortion (THD) reduction, power factor (PF) correction, peak current reduction for nonlinear loads, and soft load variation effects, as well as their capability to limit fault current. To this aim, the capabilities of BDCR-FCLs have been studied through various simulated case studies in PSCAD/EMTDC software V5.0.1, in addition to experimental tests considering an AC microgrid connected to a DC system. The experimental and simulation investigations verify the superior multifaceted functionalities BDCR-FCLs introduce in addition to their excellent fault current-limiting capabilities. The results show that PF improved by 6.7% and 7%, respectively, in simulation and experimental tests. Furthermore, the current THD decreased by 20% and 18% in the simulation and experiment, respectively.

VBL Collaborative: An Approach for Teaching Complex Transmission Line Problem Statements

Abstract— The educator's choice of techniques is intended to foster a strong love of learning. The different methods of learning can improve learners' abilities. The need of pupils to learn cannot be met by only conventional teaching. When pupils graphically answer the provided question, this is clearly seen. This paper studied students’ performance for the graph based topic ‘Smith Chart’ for the course ‘Radar and Microwave Engineering’ for the third year of engineering students. Total 64 students of the same class considered for the experiment. Video based learning (VBL) is methodology is used in this paper. Total 64 students learn the said chart (Smith Chart) through videos. VBL along with collaborative approach is carried out for experimental group. The two group posttest is carried out. The two group post test results presented in the paper. The assessment is carried out w.r.to Learning Outcomes (LO) and Bloom’s Level (BL). The objectives of the study are to introduce and make students understand Smith chart (BL: Understand, LO1); to determine transmission line parameters and impedance along the line (BL: Apply, LO2); to examine the effect of load variations on transmission line parameters. (BL: Analyze, LO3). The results w.r.to LOs and BL are presented in this paper for both control and experimental group. To assess the level of effectiveness of the intervention feedback is taken from experimental group. Almost 96% students liked the activity. Keywords— smith chart; transmission line; LO; BL; VBL

Design of suspension control system for bearingless induction motor using fuzzy-I controller

In the bearingless induction motor (BIM), the rotor of BIM is supported by the magnetic force, the radial position control technique is studied in this paper, an approximation and simplification are used to create a linearized model of suspension system. The objective of this paper is to design a control system that overcomes the limitations of the traditional controller and to improve the control performance and achieve high stability, even if it is exposed to external disturbance and internal disturbance (changes in load or speed). In order to solve this problem, the proposed controller is based on the fuzzy-I controller that combines the positive features of both fuzzy logic and the integration. In comparison with the conventional PID, the results show that the fuzzy-I controller reduces the peak-to-peak rotor deviation by 23% under effect of external disturbance force and 31% under effect of speed variation and 9% under effect of load variation.

Battery Electric Tractor Powertrain Component Sizing With Respect To Energy Consumption, Driving Patterns and Performance Evaluation Using Traction Motor

In this paper sizing the powertrain of battery electric tractor (BET) including major farming implements are investigated for various real world driving patterns. Powertrain components are modelled using torque-load characteristics which are function of speed, acceleration, plowing implement and depth of plowing and texture of the soil. Effect of load variations on powertrain performance and energy consumption are also explained in detail. In this powertrain design major farming implements like chisel plough, mould board plough, field cultivator, sweep plough are considered. Tractor hauling a trailer carrying goods with 2000 kg weight is also considered for powertrain design. Typical operating velocities of 18, 15 and 25 kmph are taken for sand, tillage and asphalt surfaces respectively for tractor trailer applications and 7 kmph for plowing applications. The dynamic model of the powertrain is modelled in MATLAB/SIMULINK. PMSM is selected as a traction motor and its performance is evaluated in MATLAB/SIMULINK. Same has been verified using real-time Hardware in loop (HIL) simulator with help of OPAL-RT (OP5700).

Towards predicting dynamic reliability of bridge spans

In conditions of increasing impact of temporary live load, a premature wear of bridge superstructures occurs, operational strength and durability decrease. The paper discusses the dynamic reliability of the load-bearing elements of superstructures within the frame of ensuring the structure safety during operation, with regard to defects and overloads. Reliability is considered within the framework of random events and processes based on the possible superstructure exit beyond its serviceability based on the statistical dynamic properties. The par ametric and structural reliability is considered. Based on the mathematical statistics and random numbers theories, the dynamic reliability theory is characterized by the quality deployed in time. The effect of load variation for a long time is considered. The possibility is predicted for changing resources and structure failure. The dynamic reliability conditions are approximated based on the Gauss and Weibull distribution curves. Mathematical expressions are given to the structure indestructibility. The superstructure failure is considered with respect to possible overload using the principle of accidental release.

Robust sliding-mode control for maximum power point tracking of photovoltaic power systems with quantized input signal

A robust sliding-mode controller is proposed for maximum power point tracking in photovoltaic power generation system. Thanks to using hysteresis quantized inputs, the chattering phenomena, as the main weakness of the sliding mode controllers, is removed. Also, the external disturbances, model uncertainties, environmental and load variation effects are attenuated in the proposed controller scheme. The upper bound of the disturbance is assumed to be unknown and is estimated with an appropriate adaptive rule. Using the Lyapunov theory, the stability of the proposed scheme is verified and analytically proved. MATLAB simulation results confirm that the undesired effects of disturbances and chattering are simultaneously removed, as is proved in the theoretical analysis.

Automatic Indoor Air Quality Control of COVID -19 Patient Facilities Using Type-2 Fuzzy Controller

Big facilities can be used to set up cohort wards for severe and critical COVID-19 patients. The purpose of carbon dioxide and humidity control is to provide healthy air for breathing by both diluting the pollutants originating in the building and removing the pollutants from it. In this paper, for proper mechanical ventilation to maintain indoor air quality (IAQ), a Self-tuned Interval Type-2 Fuzzy PI controller (SIT2FPIC) is proposed. 49 fuzzy if-then rules are used to tune the Interval Type-2 Fuzzy PI controller (IT2FPIC) for proper functioning and to reduce the parameter variations. Correlations of CO2 concentration and air humidity are studied to maintain the air quality in COVID-19 facilities. Mathematical models of CO2 concentration and air humidity in hospitals or temporary COVID-19 facilities are developed considering the presence of COVID-19 patients, doctors, nurses, etc in the room. The control and monitoring of room air quality are very much essential for any infectious diseases like coronavirus. To maintain the air quality in terms of humidity and carbon dioxide, the proposed SIT2FPIC is applied to the mathematical model of humidity and carbon dioxide for the simulation study. The effectiveness of the proposed controller in mechanical ventilation in the treatment facilities is shown by a comparative study of different transient parameters. Effects of load variations in the model are also studied to check the usefulness of the proposed scheme.

STUDI PERANCANGAN PISAU PADA MESIN PENCACAH PLASTIK MENGGUNAKAN FINITE ELEMENT ANALYSIS

The amount of plastic waste each year will increase by 10% every year which is a problem for a country. Therefore, proper processing of plastic waste needs to be done. Before being processed into plastic waste processing, it is necessary to have a chopping process using a plastic chopping machine. The plastic chopping machine has an important component, namely the chopping knife. Before carrying out the knife manufacturing process, it is necessary to validate the design of the blade that is used with its loading. Model simulation using software is one way to quickly validate the model. This study aims to determine the effect of loading variations on stress, strain, deformation and safety factors of the model. The use of ANSYS R17.2 software is used to analyze the chopping machine knife model with a variation of 5kg / hour, 10kg / hour, 20kg / hour and 50kg / hour capacities. The result is that the stress, strain and deformation parameters have an increase in value with increasing loading variations. The greatest values of stress, strain and deformation are in the variation of 50kg / hour respectively 64.995 Pa; 336.76 and 56,358 x 10-11mm. The value of the safety factor for all variations of loading has a value of 15. The value of the safety factor means that the design of the plastic chopping knife is safe to use up to a loading of 50kg / hour

Conflict and Sensitivity Analysis of Vehicular Stability Using a Two-State Linear Bicycle Model

Vehicle parameters and operation conditions play a critical role in vehicular handling and stability. This study aimed to evaluate vehicle stability based on cornering tire stiffness integrated with vehicle parameters. A passenger vehicle is considered in which a two-state linear bicycle model is developed in the Matlab/Simulink. The effect of the vehicle parameters on lateral vehicle stability has been investigated and analyzed. The investigated parameters included CG longitudinal position, wheelbase, and tire cornering stiffness. Furthermore, the effects of load variation and vehicle speed were addressed. Based on a Fishhook steering maneuver, the lateral stability criteria represented in lateral acceleration, yaw rate, vehicle sideslip angle, tire sideslip angles, and the lateral tire force were analyzed. The results demonstrated that the parameters that affect the lateral vehicle stability the most are the cornering stiffness coefficient and the CG longitudinal location. The findings also indicated a positive correlation between vehicle properties and lateral handling and stability.

Modelling of load variation effect on the steam power plant heat rate and performance using Gatecycle

One of the notable problems faced by power plant sector is the continuous increasing of policy urging air pollutant reductions such as NOX, SOX, and CO2. Therefore, there is a substantial necessity for power plant to conduct the most efficient scheme. One of the viable solutions is examining the present condition, evaluating as well as changing into better result. The present paper deals with the study of the powerplant performance running on fuels. In particular turbine maximum continuous rate (TMCR) were compared with other values. The outcomes show that heat rate, efficiency and fuel flow of the boiler increased respectively as a caused from the increasing load. In equipment level, heat transfer conducted by boiler is the biggest compared to another installed equipment. The result analysis highlighted that the design is able to be a replacement or insight for future operational data.

Experimental Analysis of Solar Assisted Refrigerating Electric Vehicle

Most refrigerating systems are driven by an internal combustion engine that increased the conventional vehicle’s oil consumption and tailpipe emissions. The solar-assisted refrigerating electric vehicle (SAREV) system powered by a hybrid energy mode has been designed. The hybrid energy (solar + grid) was stored in the battery bank to complete this vehicle’s necessary functions. The PV panels are prominently incorporated into this vehicle rooftop to charge the battery bank. In this study, the integrated system was driven by a hybrid energy mode that reducing the wastage and deterioration during temporary storage and transportation in different areas. The performance of the integrated system was tested under different operating conditions. The effect of load variation on maximum speed and travelling distance of vehicle was analyzed. The battery bank charging and discharge performance were studied with and without solar energy. The refrigerator was consuming 116 Wh energy per day to maintain a -12 oC lower temperature on the no-load condition at the higher thermostat position. The refrigerator was run continuously for 4-6 days on battery bank energy and 7-10 days on the full load condition of hybrid energy. The vehicle was travelling at a maximum of 23 km/h speed on full load condition. The vehicle needed torque 14-16 N-m at the initial phase for each load condition. Torque demand was decreasing with the increasing speed of the vehicle. The full-charged battery bank’s initial voltage was 51.04 V, and the cut-off voltage was 46.51 V. The vehicle was covering a distance of 62.4 km with the battery bank alone at full load condition. It was travelling 68.3 km distance with hybrid energy mode. The vehicle’s integrated system was the best in maintaining battery performance, power contribution capability, and drive range enhancement.

Energy, Exergy, Economic and Environmental Analyses of Air-Based High-Temperature Thermal Energy and Electricity Storage: Impacts of Off-Design Operation

Abstract The present study presents a comprehensive assessment of the impacts of the off-design operation of an air-based high-temperature thermal energy and electricity storage (also known as high-temperature heat and power storage) system on its energy, exergy, economic, and environmental aspects. Here, the effects of load variations on the mass flowrate, pressure ratio, and isentropic efficiency of the turbomachinery are considered to give the most accurate possible picture of the techno-economic aspects of the performance of the system. The results of such an assessment will be extremely useful in achieving the optimal performance of the energy storage system while working parallel with solar and wind power plants. The results prove that the system will present high overall energy and exergy efficiencies of 91.5% and 88.16% when working at full load all the time. These indices, however, will be as low as 67.8% and 65.9% at an annual average operation load of 70% and even further lower to 34% and 32.7% at 40% load, respectively. The payback period of the system will decrease from 11 to 23 years when the operation load falls from 100% to 80%. The environmental effects of such an energy storage unit for an energy market like Denmark (for instance) will be about 6355, 3227, and 823 tonnes of reduced equivalent carbon-dioxide when working at 100%, 70%, and 40% loads, respectively.

A Microgrid Based on Wind-Driven DFIG, DG, and Solar PV Array for Optimal Fuel Consumption

This article presents a green energy solution to a microgrid for a location dependent on a diesel generator (DG) to meet its electricity requirement. This microgrid is powered by two renewable energy sources, namely wind energy using doubly fed induction generator (DFIG) and solar photovoltaic (PV) array. The solar PV array is directly connected to common dc bus of back-to-back voltage source converters (VSCs), which are connected in the rotor side of DFIG. Moreover, a battery energy storage is connected at the same dc bus through a bidirectional buck/boost dc–dc converter to provide a path for excess stator power of DFIG. The extraction of maximum power from both wind and solar is achieved through rotor side VSC control and bidirectional buck/boost dc–dc converter control, respectively. A modified perturb and observe algorithm is presented to extract maximum power from a solar PV array. Moreover, the control of load side VSC is designed to optimize the fuel consumption of DG. A novel generalized concept is used to compute the reference DG power output for optimal fuel consumption. The microgrid is modeled and simulated using SimPowerSystems toolbox of MATLAB for various scenarios such as varying wind speeds, varying insolation, effect of load variation on a bidirectional converter, and unbalanced nonlinear load connected at point of common coupling. The DFIG stator currents and DG currents are found balanced and sinusoidal. Finally, a prototype is developed in the laboratory to validate the design and control of it.

Qualitative Analysis of 3D Routing Algorithms in 3×3×3 Mesh NoC Topology Under Varying Load in Bio-SoC

This article presents a qualitative analysis of a 3D routing algorithm in a 3×3×3 mesh NOC topology. The effect of load variation on throughput, total energy, and maximum delay for different types of routing is observed. The simulation was performed on an Access NOXIM network-on-chip simulator under random traffic conditions. The research involves quality parameters like total packets received, total received flits, global average delay (cycles), global average throughput (flits/cycle), throughput (flits/cycle/IP), max delay (cycles), total energy (J), average power (J/cycle), average power per router (J/cycle), and average waiting time in each buffer. In this article, it was observed after comparing all the routing techniques against the mention parameters the XYZ routing techniques was found perform better followed by West first, and North last, while poor performance was observed against odd-even, negative first, and fully adaptive.

Simplified Hybrid AC–DC Microgrid With a Novel Interlinking Converter

Hybrid ac–dc microgrids (HMG) have become more popular recently because of their superior features in comparison with pure ac and dc microgrids (MGs). HMGs have fewer power converters and are more flexible than pure ac and dc MGs, but the number of converters in HMG is still significant, especially when the dc part of HMG has several voltage levels. A new simplified and more flexible architecture for HMGs that features a new multiport interlinking converter (IC) is proposed in this article. Using the proposed IC, the number of power electronic converters in an HMG with several dc bus voltages can be reduced without increasing the number of active switches in the IC or the complexity of its control system. In this article, the new simplified HMG architecture is presented, and the operation of the proposed IC as a single unit and as a part of a simplified HMG are explained, along with its features. Experimental results obtained from a scaled-down prototype are also presented to confirm the feasibility of the multiport interlinking converter. Simulation results that show the effect of load variations in the intermediate bus architecture dc bus on the operation of the HMG are also presented as well.

Building thermal load management through integration of solar assisted absorption and desiccant air conditioning systems: A model-based simulation-optimization approach

Performance of standalone air-conditioning systems is affected while simultaneously handling both sensible and latent building loads. Model-based simulation and optimization is one of the best ways to analyze system's performance under load fluctuations at the initial design stages. Therefore, in the current study, seasonal transient simulations of an Integrated Absorption Desiccant System are carried out using TRNSYS to handle sensible (10.94 kW peak) and latent (4.44 kW peak) cooling load separately. Radiant cooling with chilled water from an absorption chiller mainly handles sensible cooling load, while the latent load is achieved by a solid desiccant dehumidification system. Initially, key components of the system are modeled in TRNSYS including a flat plate solar collector system, desiccant wheel, heat recovery wheel, and absorption chiller. Afterwards, the integrated model is coupled with GenOpt to optimize the solar fraction and thermal coefficient of performance by varying collector area, flow rate in the collector loop, flow rate in load side loop, and volume of storage tank. The resulted optimized value of solar fraction is 57.50%, and COPth is 0.55 for standalone absorption system, whereas the solar fraction of 56.20%, COPth of 1.52 are achieved for IADS. In addition, the effects of load variation in terms of sensible to latent load ratio on regeneration heat required for both IADS and conventional desiccant system are also analyzed. A critical value of load ratio of 0.75 is also observed in terms of heat regeneration requirements to compare the both systems. The proposed approach and analysis will be very helpful for HVAC designers for optimal system performance through separate load handling, especially at the initial design stage.