Analysis Of Transient Characteristics Research Articles

Measurement and Analysis of Transient Information Characteristics of IOT Equipment Using Graphical Programming

The switching on and switching off operation of some IOT devices is a complex physical, chemical and mechanical nonlinear transient process, which contains a lot of information. The information has distinction, stability and clear physical meaning. Due to the short time of transient process and the rapid change of waveform and characteristic parameters from time to time, it is difficult for traditional test instruments to capture the characteristics of voltage, current and power consumption in the transient process. Therefore, this paper develops a set of transient characteristic test system of IOT equipment by using the graphical programming software LabVIEW, which realizes the accurate measurement, automatic analysis and display of transient process waveform and characteristic parameters. Taking the operating coil of an electronic product as the test object, the transient characteristics in the whole process of on-off, closing process and breaking process are tested and verified by using the test system, which improves the efficiency of detection and analysis of the performance of IOT equipment.

Modeling and Analysis of Transient Reactive Power Characteristics of DFIG Considering Crowbar Circuit under Ultra HVDC Commutation Failure

Ultra high voltage direct current (UHVDC) transmission is an effective means of long-distance transmission of renewable power generation, which has obtained a lot of research and practical applications. The commutation failure is a common DC transmission fault, which will cause the voltage amplitude of the sending ac grid in UHVDC system to first decrease then increase. The existing transient mathematical models of the wind power generation system (WPGS) are difficult to apply to scenarios where the grid voltage changes continuously. A mathematical model suitable for commutation failure is established to analyze the transient reactive power characteristics of the doubly fed induction generator (DFIG)-based WPGS with the consideration of the crowbar circuit trigger. The correctness of the mathematical model is validated by an experiment based on the control hardware-in-loop (CHIL) platform. Based on the proposed mathematical model, the influence of the crowbar parameters on the reactive power output of the DFIG is analyzed, and the selection of crowbar parameters to suppress the overvoltage of the sending ac grid is investigated. A simulation model is built based on Matlab/Simulink to verify the overvoltage suppression effect of the proposed selection scheme.

Analysis of power system transient stability characteristics with the application of massive transient stability simulation data

A large number of simulation results will be generated during the calculation of the power system digital simulation. Manual analysis of massive numerical results is inefficient and error-prone. Besides, some imperceptible operating rules of power system operating mode may be ignored. In order to solve these problems, a transient stability assessment method based on deep learning is proposed in this paper. By analyzing simulation data, the relationship between power grid stability characteristics and the set operation mode is constructed. According to these research results, the calculation and analysis of power system transient stability will be effectively supported.

Coupled Analysis of Transient Aerodynamic Characteristics of the Coach under Crosswind in Different Situations

The purpose of this work is to investigate transient aerodynamic characteristics of the coach under the crosswind in straight-line situations with different uniform speeds and uniform accelerations. The transient aerodynamics caused by different speed changes are analyzed using the real-time interaction between aerodynamic simulation and dynamic simulation. The target model is a simplified coach on a full scale. The SST (Menter) K-Omega Improved Delayed Detached Eddy Simulation and overset mesh technique are used to predict the transient aerodynamic loads. The accuracy of the turbulence model is verified by a wind tunnel experiment of the 1/7th scaled coach model. The present results show that the transient aerodynamic loads have different locations of maximum side force and the holding duration of yaw moment for different constant speeds. The speed becomes larger, and the position where the side force is maximum becomes farther away. The holding duration of the top yaw moment is larger simultaneously. Moreover, proper acceleration for low initial driving speed and crosswind of small influence range could build up stability. High speed driving in gust wind is not suggested for unskilled drivers.

Transient Characteristic Analysis of Turbine Generator Based on Separated Partial Finite Element Model

This article presents an effective modeling method for electric machines to reduce the computational cost of finite element (FE) analysis coupled with circuit equations. In this method, center and end regions of the machines are separately modeled. The center of the machines is partially modeled considering their periodic structure. As a result, the total number of elements can be decreased. Moreover, the computational accuracy is kept unchanged by introducing two correction coefficients which adjust the total amount of magnetic flux across the coils. The proposed method is applied to the steady-state characteristic analysis of a turbine generator. It is shown that the proposed method can reduce the computational time to about one-third in comparison with the conventional FE model, while the computational results almost coincide with the measurements. Then, the proposed method is also applied to a time-consuming eddy current analysis of the turbine generator for estimating its transient characteristics. It is shown that the estimated transient constants of the turbine generator are in good agreement with the measured results.

Analysis of transient characteristics for zinc-nickel single flow battery considering side reactions

Analysis of transient characteristics for zinc-nickel single flow battery considering side reactions

Research on Reduced-Order Modeling of Droop Controlled Inverter Suitable for Analysis of Transient Characteristics

Under the background of a large number of converters connected to the power grid, the converter’s weak overcurrent capability and poor anti-interference ability bring challenges and hidden dangers to the transient safe and stable operation of the power grid. It is urgent to carry out the transient characteristics analysis of the converter. Numerical simulation calculation is an important means to study transient characteristics. However, numerical simulation is time-consuming and poor in generality, which greatly limits the study of transient characteristics of systems with multiple converters. In this paper, the vertical control is the object, and the inverter reduced-order simplified model suitable for different transient stability problems is studied. First, a full-order model of the droop control inverter is established, and the singular perturbation method is used to complete the extraction of system characteristic roots and the analysis of participating factors. Then, according to the droop control of the inverter’s power angle, voltage, and frequency transient response process, accuracy and rapidity are selected as the goals, and a reduced-order simplified model suitable for different transient stability analysis is obtained. The transient characteristic analysis of the numerical simulation of the converter system provides a reduced order reference.

Multi-body dynamics modeling and transient characteristics analysis for a folding wing

The investigation of modeling the time evolution of a folding wing during the morphing process and the dynamic characteristics analysis is carried out. The governing equations with uniform form are developed from the integration of floating frame method in multi-body dynamics and component mode synthesis in structural dynamics. The time-dependent aerodynamic force is taken into the governing equations. The equation achieves the time-dependent coupling between structure and aerodynamics and avoids the data transmission and low efficiency, which holds true for the multi-segmented folding wing. The relative parameters in constraint equations are easily modified to be applied to both slow and fast-varying processes for a folding wing. Also, the influence of the velocity and attack angle on transient responses can be investigated. Transient response analysis shows that slower morphing means more stable transient responses. The flexibility of the folding wing has the significant influence on transient responses. To some extent, the aerodynamic force can be beneficial to the morphing process.

An Integrated Scheme for Transient Characteristics Analysis and Two-Stage Stability Assessment of Wind-Fire Power System Based on W-DGAN and Uniform Information Coefficient

An Integrated Scheme for Transient Characteristics Analysis and Two-Stage Stability Assessment of Wind-Fire Power System Based on W-DGAN and Uniform Information Coefficient

Influence of lightning surges on wideband‐frequency model of LCC‐UHVDC converter station

One of the leading causes of power system outages is lightning surges. A precise calculation of lightning overvoltages across insulators has vital significance for the investigation of lightning outages. This study investigates the impact of different lightning surges for the analysis of transient frequency characteristics of line commutated converter (LCC) based ± 800 kV ultra-high-voltage direct current (UHVDC) converter station by developing a wideband (WB) model of the converter station. The influence of lightning flashover criterion (LFC) of double exponential and Heidler surges methods on insulator/gap for precise lightning withstand level is examined. An analytical comparison for LFC of insulator/gap installed at high altitude transmission lines by incorporating the IEEE volt/time curve, CIGRE leader propagation (LP) and improved LP methods is presented. The proposed WB model explores the novel attributes of high-frequency transfer characteristics and the coupling mechanism of transient frequencies passing through the converter station. Moreover, the effect of internal frequency dependant DC line faults on the WB model is examined. The analysis presented here aims to investigate issues like overvoltage, electromagnetic disturbance prediction, insulation design of the equipment and standardisation of sensitivity issues that are being faced by the present relay protection systems.

Research on SVG Electromagnetic Transient Simulation Technology of Large-scale Offshore Wind Power Base

Based on the control hardware in-loop simulation technique, the article built the SVG control hardware in-loop electromagnetic transient real-time simulation platform, and completed the simulation analysis of the transient reactive response characteristics of the SVG controller under the ideal grid. Relying on the SVG control hardware in-loop simulation platform, using code encapsulation cryptography, a pure digital model of the SVG control system dynamic link library was established. The feasibility of the SVG control hardware in-loop real-time simulation platform and DLL model was verified by “three-line check” of the control hardware in-loop simulation model - DLL model - field experimental data curve, which provides a simulation analysis solution for the analysis of SVG transient response characteristics of large-scale offshore wind bases.

Effect of phase-lags on the transient waves in an axisymmetric functionally graded viscothermoelastic spherical cavity in radial direction

This paper aims to present the analysis of transient wave characteristics in a functionally graded viscothermoelastic infinite medium with spherical cavity in the context of generalized thermoelasticity. Continued series solution is used to solve simultanious differential equations for evaluating the field variables. Convergence of the series solution is implemented and investigated that the series of functions are absolutely and uniformly convergent. The formal solution for the field variables are obtained analytically and represented graphically. The effect of grading index and different theories of generalized thermoelasticity are also shown graphically to examine the behavior of the variations of the field variables.

Analysis of Transient Inhomogeneous Flow and Thermal Characteristics in a Drying Room via Large Eddy Simulation

AbstractTo optimize the flow structure in a soft‐capsule drying room, the notable inhomogeneous characteristics of flow behavior and thermal feature are numerically explored. An advanced three‐dimensional numerical model is established and a verified large eddy simulation (LES) model is adopted. The results indicated that there is a highly inhomogeneous flow structure especially approaching the bilateral region of the drying room, mainly caused by the large velocity gradient whereas a relatively uniform flow structure is observed in the middle region. In the drying process, the inhomogeneous flow feature is sensitive to the increased inlet velocity and aspect ratio λ. It was found that a suitable inlet velocity and a small aspect ratio λ can provide a better drying flow environment.

Analysis of Transient Pressure Source Characteristics of Trim Balance Pipeline System

Based on the hydraulic calculation of AMEsim software, adjust the pipeline and working conditions of the trim balance system, and explore the influence of water transfer pressure, pipeline length and valve closing time on the transient pressure fluctuation during the working process, and obtain the pressure change law and corresponding Relationship, according to the analysis gives preliminary optimization suggestions, sums up the scheme and scope of reducing water transfer pressure, shortening pipeline length, extending valve closing time, providing reference for optimizing system design and control, and proposing control from noise source level The method of transient noise caused by water hammer phenomenon provides an idea for controlling the transient noise of pressurized pipelines of ships and underwater vehicles.

Operational analysis of transient characteristics in a small scale turbojet engine

Operational analysis of transient characteristics in a small scale turbojet engine

Parçacık Sürü Optimizasyonu Ayarlı Türev Etkisi Filtreli Bir PID Denetleyici için Hata Tabanlı ve Kullanıcı Tanımlı Amaç Fonksiyonlarının Performans Analizi

In this study, we investigate the performance analysis of transient and steady state characteristics of the commonly used error-based objective functions (EBOF) such as integral of squared error (ISE), integral of time weighted squared error (ITSE), integral of absolute error (IAE), and integral of time weighted absolute error (ITAE) and a user-defined objective function (UDOF). In optimization process, particle swarm optimization (PSO) algorithm tuned proportional-integral-derivative controller with derivative filter (PIDF) is employed for a second order plus dead time (SOPDT) test system. Simulation results shows the superiority of the UDOF in terms of settling time, overshoot, and settling minimum value compared to EBOFs.

Analysis of Pressure and Production Transient Characteristics of Composite Reservoir with Moving Boundary

The mathematical model of composite reservoir has been widely used in well test analysis. In the process of oil recovery, due to the injection or replacement of the displacement agent, the model boundary can be moved. At present, the mathematical model of a composite reservoir with a moving boundary is less frequently studied and cannot meet industrial demand. In this paper, a mathematical model of a composite reservoir with a moving boundary is developed, with consideration of wellbore storage and skin effects. The characteristics of pressure transient in moving boundary composite reservoir are studied, and the influences of parameters, such as initial boundary radius, moving boundary velocity, skin factor, wellbore storage coefficient, diffusion coefficient ratio, and mobility ratio on pressure and production, are analyzed. The moving boundary effects are noticeable mainly in the middle and late production stages. The proposed model provides a novel theoretical basis for well test analysis in these types of reservoirs.

Transient Characteristic Analysis of Induction Motor at the Bus Transfer by Standby Power Source in the Blackout

This paper discusses currently used bus transfer methods, and presents a new method to successfully perform fast bus transfer to connect to the standby power source in the event of a supply disruption. Generally, the load of the induction motor is equipped with two independent power supplies to increase the stability of the power supply. If main power source supplies become unavailable due to a power outage, the standby power source connected in parallel is designed to operate. When blackouts occur, the voltage drops to a very low value in a very short time, but the current hardly flows immediately. When a voltage drop occurs due to the blackout, the speed of the motor starts to decrease. When the power is supplied by the standby power source, it is necessary to keep the torque level at a safe level because a large current may cause a serious excessive torque to the motor shaft. The induction motor requires stable power supply at all times during operation of the load. In this study, we propose a method to reduce current and torque by providing a current signal instead of a voltage signal as a breaker input signal in order to quickly switch the backup power source in the event of the blackout.

A Coupled Model of Two-Phase Fluid Flow and Heat Transfer to Transient Temperature Distribution and Seepage Characteristics for Water-Flooding Production Well with Multiple Pay Zones

Temperature is one of the most prominent factors affecting production operations, predicting the accurate wellbore-formation temperature in a water-flooding production well is of great importance for multiple applications. In this paper, an improved coupled model of oil–water two-phase fluid flow and heat transfer was developed to investigate the transient temperature behavior for a producing well with multiple pay zones. Firstly, a novel method was derived to simulate the water saturation and the water breakthrough time (WBT) for tubing, which are key monitoring parameters in the process of water flooding. Then, we incorporated water saturation and an equation set for immiscible displacement to calculate the seepage velocity and the pressure of the two-phase fluid in the pay zones. Next, the upward seepage velocity of the tubing fluid change with depth was focused on, and the proper coupled initial and boundary conditions are presented at the interfaces, therewith the implicit finite difference method was used to compute the transient temperature with the input of the seepage characteristics for the reservoirs. Meanwhile, the validity of the proposed model has been verified by the typical model. Finally, a sensitivity analysis delineated that the production rate and the production time had a significant impact on the tubing fluid temperature. The overburden was hotter with a lower volumetric heat capacity or a higher thermal conductivity. In addition, the sensitivity of the porosity and the irreducible water saturation to formation temperature was significantly different before and after the WBT. The coupled model presented herein helps to advance the transient seepage characteristics analysis of pay zones, the precise temperature prediction is very useful for reservoir characterization and production analysis purposes and provides insight for designing the exploitation scheme in deep reservoirs and geothermal resources.

Transient characteristics analysis of lead-based reactor from forced circulation to natural circulation

Natural circulation and forced circulation are two types of normal operation conditions that usually appeared in nuclear power systems. However, it should be noted that the reactor safety and reliability can be jeopardized due to significant fluctuation of the mass flow rate through the lead-based reactor core during the conversion from forced to natural circulation. Therefore, a model of 10MWth lead-based reactor based on RELAP5 mod4.0 is developed to analyze the effects of the five factors on the transient characteristics, including the power control system, the initial steady-state power level, the human intervention, shutting down each main pump one by one and the bypass of the main pump separately. The results show that using power control system can obviously reduce the transition time and realize the rapid response of the reactor during the conversion. Moreover, a higher initial power level results in a larger power fluctuation, a larger maximum value of cladding peak temperature and a stronger natural circulation. As a result, the maximum initial power level can be obtained according to the cladding temperature limitation (823 K). Especially, the optimized control strategy taking into account the combined effects of three factors, namely human intervention, shutting down each main pump one by one as well as the bypass of the main pump, can increase the maximum initial power level from 45%FP to 75%FP.