Jong-Ian Tsai

Parameter estimation of induction machines under no-load test

This paper uses time-varied signals of voltage, current and rotor speed to compute the equivalent circuit parameters, moment of inertia, and friction coefficient of an induction machine. A time-varied impedance can be found by the time-varied voltage and current. From the variation of impedance to the rotor speed, the parameters of steady equivalent circuit can be found. According to the equivalent circuit and rotor speed, the torque can be found via established dynamic system model. On the basis of torque and rotor speed with time, moment of inertia and friction coefficient of the motor can be obtained. This paper uses the least mean square method to solve the above parameters. The initial values of least mean square are also described in this paper. This paper used estimated parameters to simulate the starting states of an induction machine to compare with the real one, accordingly, practicability and accuracy of this method has been proven.

Complete parameter estimation of induction machines by time-varied parameters

This paper proposes a method to find the equivalent circuit parameters, moment of inertia, and friction coefficient of an induction machine. The reference data include time-varied signals of voltage, current and rotor speed. By the time-varied voltage and current, a time-varied impedance can be found. The parameters of equivalent circuit can be found from the variation of impedance to the rotor speed. And then, the torque can be found via dynamic system model and rotor speed. From the torque and rotor speed with time, moment of inertia and friction coefficient of the motor can be obtained, too. The least mean square method is used to solve the above parameters in this paper. The initial values of least mean square are also described. The comparison of the simulated performance in starting states of an induction machine with the real one is discussed in this paper, accordingly, practicability and accuracy of this method has been proven.

Turbine-generator blade and shaft torisonal torques due to line faults in six-phase transmission systems evolved from three-phase double-circuit line systems

Due to a restricted right-of-way and many factors, some of the local areas in Taiwan have become increasingly difficult to build new transmission lines. Since the majority of Taiwan power loads are located in the Norton, the demand of promoting transmission power could be of great urgency owing to the large amounts of power transferring from the South to the Norton. Aimed at overcoming this problem without changing the original conductors of the double-circuit transmission lines, the six-phase transmission scheme which could be one of the best schemes is presented and has several advantages such as transient stability enhancement, minimal corona, electric and magnetic fields, and radio interferences. As a result of the successful commercial operation of six-phase transmissions, the utility planner inevitably faces with the issue for the impact of turbine-generator torsional vibrations in the initial stage of the expansion into the a six-phase network. From the simulation comparisons between the three-phase double-circuit and evolved six-phase system, the latter offers better stability characteristic without deteriorating torsional vibrations from the viewpoint of the same line voltages. For the case of the same transmission capability, it significantly reduces the torsional vibrations. These conclusions provide a constructive suggestion for the department of generation and transmission.

TAS/MRC diversity system design over fading channel model of arbitrary Nakagami-m

This paper considers Transmit Antenna Selection /Maximal-Ratio Combining (TAS/MRC) system design over arbitrary Nakagami-m channel model. An exact expression for bit error rate (BER) in independent and identically distributed (i.i.d.) Nakagami-m fading channels is derived as a single infinite series of tabulated function while the fading index is a real value. The expression holds for arbitrary m parameters and provides a comprehensive framework for TAS/MRC system design with a specified BER performance of binary modulation. At high signal-to-noise ratios (SNRs), the asymptotic BER expression is derived to show a full diversity order equal to the product of the m parameter, the number of transmit antennas and the number of receive antennas. The derived expression is verified by Monte Carlo simulations.

Fast parameter analysis of the complex exponential signal by the Newton-Raphson Method

This paper proposes the algorithm to analyze parameters of the complex exponential signal by the Newton-Raphson Method. The parameters of complex exponential signal include angular velocity, damping, amplitude, and phase. This algorithm takes the time-domain data as the reference. According to differing positions on the complex plane, the relative algorithm will be established. The nonlinear equations could be quickly solved by the iterative calculation. This analysis result can demonstrate precise complex exponential parameters. This method has features of fast calculation and simple framework.