Papers by Keyword: Transient Simulation

Abstract: We briefly review backward error analysis as a useful mathematical technique for improving numerical methods used for solving ordinary differential equations describing dynamical systems. Then, we show how backward error analysis-based compensation, an approach recently introduced by the authors, can be applied to the second-order Newmark method for eliminating numerical damping and achieving fourth-order convergence. The presented improvements only require modifying the physical parameters of the system and the excitation, while the Newmark method is left intact. We compare the performance of the resulting improvements with that of several other numerical methods, including a novel partitioned method based on local extrapolation.

Abstract: The high-speed switching capabilities of wide bandgap (WBG) power devices have posed challenges in accurately evaluating their dynamic characteristics, primarily due to the increasing influence of parasitic components in switching test circuits. To address this issue, we investigated the impact of parasitics by conducting dynamic tests and schematic-level transient simulation on a half-bridge switching circuit incorporating SiC MOSFETs. This comparative analysis identified specific parasitic components responsible for undesirable behaviors such as spikes and ringing in the switching waveform. Our findings provide insights into which parasitic components in the test circuit are critical for the accurate dynamic characterization of SiC MOSFETs.

Abstract: In building simulations initial conditions express the actual hygrothermal state of building envelope. For the temperature field simulations initial condition is represented by the initial temperature in the body profile at the start of heat transfer. In-structure temperature varies quickly so temperature initial conditions are often neglected. The contribution shows various temperature initial conditions determination for insulated construction of outdoor test cell. We confirmed importance of setting the initial moisture condition for numerical analysis of complex heat and moisture transfer in multi-layer building components. Comparison of measured and calculated temperature profiles in structure show correctness initial condition consideration.

Abstract: The steady-state mathematical model of Smith-connection three-winding single-phase capacitor motor is established, and the capacitance calculation formula in minimum voltage unbalance condition is deduce .Based on this, by MATLAB simulated program, a operation simulation of Smith single phase capacitor motor that in single-phase 220V power supply and in single-phase 380V power supply is developed. The simulation results agree with the experimental results.

Abstract: In order to study the maximum strain of steel shell surface under the impact of a falling ball, a thin shell model and the strain time history curves of impact are achieved by ANSYS/LS-DYNA. A deformation behavior of the shell was calibrated from the test which uses a ball free fall and some resistance strain gauges pasted to the inner surface of an iron shell box. The gauges are connected as inputs to a Wheatstone bridge circuit and an Oscilloscope is used to observe the output. The results show the impact test and ANSYS/LS-DYNA simulation results are smoothly consistent with the strain of the test at the maximum strain amplitude of the model, and the maximum difference is 9.5%. Accurate results can be achieved by combining the test method and the simulation approach as an industrial application.

Abstract: For traditional voltage and reactive power control (VQC) of substation will cause frequent adjustment of transformer taps and switching of capacitor banks, which exerts a certain impact on system voltage, the static synchronous compensator (STATCOM) is supposed to be installed in the substation to improve the effect of VQC. A coordination control strategy between STATCOM and VQC in substation based on the identification of system state is proposed in this paper to coordinate the operation between on-load tap changers (OLTC), capacitors and STATCOM. In addition, we have a research on the application effect of this strategy with BPA. The simulation results show that STATCOM plays an important role in improving the substation performance in both steady state and transient state and it can effectively reduce the frequency of tap changing and capacitor switching. Besides, the system will perform better if both of the main transformers are equipped with STATCOM than only one is configured.

Abstract: Lightning is the main reason to cause line tripping and service interruption, and its surge wave invaded into substation over the line is also the key factor which impact on the safe operation of equipments. Research on over-voltage transmission of lightning will be benefit to measure the lightning interference impact on energy metering equipments. Analyzing the transient process of the transmission line must adopt the telegraph equations. In this paper, the partial differential equations were discrete with the FDTD method. Then the equivalent power source of lightning is added at the starting point and the purely resistive load is added at the terminal. Finally, the transient propagation process of lighting was simulated in MATLAB. The three type of lossless non-uniform, lossy uniform or non-uniform transmission lines were considered.

Abstract: This paper describes the Transient Simulation Method (TSM) which predicts the steady state and performance of autorotation in forward flight. Flapping and rotational equations of motion are integrated from an arbitrary initial rotor speed, and the steady state of autorotation is obtained as a periodic solution through a transient process. The induced velocity field update method and the average thrust, lift, and drag computations during the transition are described in detail. TSM is then applied to the model rotor to validate the feasibility. High speed autorotation is simulated using an aerodynamic data set that is analyzed by the two-dimensional compressible Navier-Stokes Solver. Rotor speed variation for increases in airspeed at low shaft angle is presented and discussed. When TSM is used with sophisticated aerodynamic data analyzed as functions of the blade angle of attack, the Reynolds number, and the Mach number, the autorotation range for the collective pitch, velocity, and shaft angle can be reasonably explored.

Abstract: The simulation models of the hydraulic motor-vane pump and three-phase asynchronous motor are established based on Maxwell 2D of ANSOFT, with which the basic performance and transient characteristic are analyzed and the influence law of the hydraulic oil on the transient starting performance of special motor is obtained. The simulation results can be used to design the special motor.

Abstract: In order to obtain good starting performance of the electric scooter driven by brushless permanent-magnet direct circuit motor(BLPMDCM)，modules of RMxprt and Maxwell 2D in Ansoft software are used to build finite element simulation model of BLPMDCM. We simulated and studied the basic features and starting process of BLPMDCM. The results of internal magnetic field distribution and dynamic performance simulation are obtained when the motors are in different positions. The results provide a theoretical basis to further optimize the design, improve the starting torque and reduce torque ripple for this new type of permanent magnet motor and its control system.