Wave digital simulation of passive systems in linear state‐space form

This paper deals with wave digital modeling of passive state‐space models. The set of differential equations must be of linear state‐space form, but all parameters can be time‐variant and/or nonlinear. For such state‐space models, a canonical internally passive reference circuit is presented and used for deriving wave digital structures. In order to show the usability, special solutions for important basic linear time‐variant models are compared with wave digital simulation results. Moreover, the wave digital modeling of a nonlinear and time‐variant oscillator is discussed. Especially for a lossless oscillator an implementation is proposed, which preserves energy under finite‐arithmetic conditions. This is verified by comparing simulation results with the analytical solution of a gravity pendulum. Copyright © 2009 John Wiley & Sons, Ltd.     

Non-iterative nodal solution for transient simulation of nonlinear and time-varying elements

A non-iterative algorithm based on nodal equation formulation is proposed for transient simulation of nonlinear and time-varying elements. Terminal equations of inductors and capacitors are transformed into algebraic equations using the trapezoidal rule of integration by treating all nonlinear elements as linear and nodal equations are formulated as a set of algebraic equations. LU factorization is used for the solution of nodal equations. Variation of system elements is represented by renewing the nodal conductance matrix at each time step of the solution accordingly. In the first illustrative example, a nonlinear oscillator circuit is considered. In the second, the transient response of a transmission line with a surge arrester is computed by including the corona effects and in the third, a time-dependent primary arc model of a faulty transmission line is examined. Obtained results are compared with those obtained using EMTP and state-space method. Change of simulation time with respect to the step length of the numerical integration is also investigated.     

Improving time integration scheme for FEM analysis of MTL problems

This paper presents improved algorithm for electromagnetic transient calculations on multiconductor transmission line (MTL) achieved by improvement of the time integration when forming a local system of equations for a finite element. Improvement of accuracy was obtained by using Heun's method. Previously developed local system of equations of MTL has been obtained using the generalized trapezoidal rule (ϑ -method). The use of the generalized trapezoidal rule for the time integration sometimes causes numerical oscillations or numerical diffusion of numerical solutions. Numerical solutions obtained using Heun's method and using the generalized trapezoidal rule for different values of a time integration parameter are compared with analytical solution. It has been shown that Heun's method yields the results with much higher accuracy comparing to results obtained by generalized trapezoidal rule.     

Synchronized solution of power electronics system equations usingflexible MODELS component connected to the EMTP

The oscillations from the trapezoidal rule of integration following discontinuity and the one-time-step error from separate EMTP and TACS (or MODELS) simulations are the numerical stability and accuracy problems found in the transient study of power electronics systems using EMTP. This paper presents the technique of the synchronized solution of power electronics system equations. The proposed technique implements efficient and numerically stable approaches to model the switching circuit and control system as a MODELS component. This MODELS component is connected directly to the EMTP to avoid the one-time-step delay. Therefore, the numerical oscillations and one-time-step error in standard EMTP simulation can be eliminated     

TIME-DOMAIN MODELING OF FREQUENCY-DEPENDENT THREE-PHASE TRANSMISSION LINE RESISTANCE

Abstract

Time-domain modelling of frequency-dependent line series resistance by a discrete lumped equivalent circuit is useful for simulation, either on a digital computer or on a transient network analyzer. A resistance model that is suggested by Wheeler (1) for resistance of a lossy coaxial communication cable with ideal square-root frequency-dependent losses is adapted to model resistance of a three-phase power line with earth return. The model is solved using the trapezoidal rule with damping, which is accurate and numerically stable even for large values of time step Δt, as used in simulation of power system transients. The model is simple, accurate, computationally fast, and it can be directly interfaced with an electromagnetic transient program.     

Anticipation of digital patterns

A memristive device is a novel passive device, which is essentially a resistor with memory. This device can be used for novel technical applications like neuromorphic computation. In this paper, we focus on anticipation—a capability of a system to decide how to react in an environment by predicting future states. Especially, we have designed an elementary memristive circuit for the anticipation of digital patterns, where this circuit is based on the capability of an amoeba to anticipate periodically occurring unipolar pulses. The resulting circuit has been verified by digital simulations and has been realized in hardware as well. For the practical realization, we have used an Ag‐doped TiO_2?x‐based memristive device, which has been fabricated in planar capacitor structures on a silicon wafer. The functionality of the circuit is shown by simulations and measurements. Finally, the anticipation of information is demonstrated by using images, where the robustness of this anticipatory circuit against noise and faulty intermediate information is visualized.     

Realization of a general all‐pole current transfer function by using CBTA

In this article, a general all‐pole current transfer function synthesis procedure using current backward transconductance amplifiers (CBTAs) is proposed. The proposed configuration uses n current backward transconductance amplifiers and n grounded capacitors as the only type of passive elements. The circuit is eligible to realize any all‐pole transfer characteristics with a given strictly Hurwitz (stable) denominator polynomial. Further, it is straightforward to find the values of the passive elements from the coefficients of this polynomial by using the Routh–Hurwitz algorithm as in the realization of a two‐element kind passive network synthesis. In this sense and as far as the author's knowledge, it is the only active structure that can be synthesized like a passive two‐element kind Cauer circuit. The simulations that are performed using PSPICE exhibit satisfactory results coherent with the theory. Copyright © 2011 John Wiley & Sons, Ltd.     

多预想故障暂态稳定约束最优潮流

基于传统最优潮流模型，利用隐式梯形积分规则，将电力系统中所有发电机转子摇摆方程差分化为等式约束、将发电机转子相对摇摆角稳定极限作为不等式约束。并将二者作为暂态稳定条件加入最优潮流的等式及不等式方程组中，建立了暂态稳定安全的最优潮流模型，并结合现代内点理论对其求解。在此基础上，提出以大积分步长计算结果作故障预选和同调识别的新方法。利用Maflab进行的仿真计算显示：以该模型和内点理论结合所得的新算法收敛性良好，故障预选和同调识别结果准确可靠，能迅速地得到满足多个电力系统预想故障暂态稳定条件和目标值最优的系统稳定运行状态。     

Analog filter pair design on the basis of a gyrator–capacitor prototype circuit

The paper presents an algorithmic approach to a low‐sensitivity design strategy for analog filter pairs based on a gyrator–capacitor prototype circuit. The general structure of the prototype circuit is proposed. It assumed that the generic structure of the prototype circuit can evolve, with the use of additional gyrators, into a circuit with increased redundancy. It is shown that symbolic analysis of the prototype circuit, used to formulate a set of nonlinear algebraic equations, is necessary to achieve a sufficiently high algorithm operation speed. To find a solution to this specific system of nonlinear algebraic equations, different numerical methods are compared. The modified Hooke and Jeeves algorithm is found to be the most effective. The elaborated algorithms and programs are illustrated with the seventh‐order filter pair example. The obtained filter is better than the filter obtained using LC ladder structures with respect to chip area and power consumption, and these improvements are obtained without loss of sensitivity properties. Copyright © 2010 John Wiley & Sons, Ltd.     

A wave‐front‐time dependent corona model for transmission‐line surge calculations

For transmission‐line surge studies, the inclusion of corona discharge due to high voltage surges is important as well as the inclusion of frequency‐dependent effects. Because the charge‐voltage (q‐v) curve of a lightning surge is different from that of a switching surge, a corona model should reproduce different q‐v curves for different wave‐front times. The present paper proposes a wave‐front time dependent corona model which can express the dependence by a simple calculation procedure as accurately as a rigorous finite‐difference method which requires an enormous calculation time. The simplicity enhances the incorporation of the corona model into a line model, because a large number of models are to be inserted into the line model by discretization. The q‐v curves calculated by the proposed method agrees well with field tests. This paper also proposes an efficient method to deal with nonlinear corona branches in distributed‐parameter line model using the trapezoidal rule of integration and the predictor‐corrector method. © 1999 Scripta Technica, Electr Eng Jpn, 129(1): 29–38, 1999     

A transformation method for the solution of power switching circuits based on network topological concepts

In this paper, a general and systematic method for the analysis of varying topology power semiconductor circuits is presented. the changes of the conduction state of the semiconductor switching devices are handled by successive modifications of the tree of the circuit graph. These tree modifications are systematically reflected on a square transformation tensor. On the basis of well known network topological concepts, this generalized transformation tensor can be constructed in a relatively simple way. This tensor constitutes a flexible and powerful tool to assemble automatically the necessary on-switch current and off-switch voltage equations required for any conduction pattern. These manipulations are accomplished with a step-by-step modification procedure of the equations describing the circuit in the most previous conduction state. the basic steps of an algorithm suitable for the practical implementation of the analysis of any power switching network on a digital computer are described, and an example is used to demonstrate the effectiveness of the proposed method.     

A hybrid TLM‐FDTD method for the modelling of diffusion

A new hybrid TLM‐FDTD algorithm for solving diffusion problems is described. The method utilizes the transmission line model to define the time step and the FDTD's leap‐frog algorithm to determine the voltages and currents of the network analogue of the diffusion equation. Unlike the standard TLM method, the proposed one does not generate spurious oscillations. The method is explicit and can be used to solve highly non‐linear problems without the need to solve non‐linear equations. The implementation of a simple adaptive time‐stepping algorithm is also described. Copyright © 2000 John Wiley & Sons, Ltd.     

电力系统稳定计算加权隐式梯形积分交替求解算法的研究

对隐式梯形积分公式进行改进,引入加权因子,并采用显式格式迭代求解隐式方程组,对电力系统动态稳定进行计算。仿真结果表明,加权隐式梯形积分交替求解算法不仅保持了隐式积分数值稳定性好、可采用较大步长的特点,而且具有显式积分编程简单可靠、便于扩展的优点。同时,相较于梯形法,该算法能够消除网络操作引起的数值振荡问题,可用于电站或电网的仿真培训软件系统开发的后台仿真计算。     

基于对角隐式Runge-Kutta法的新型数字积分器研究

数字积分器是基于空心线圈的电子式电流互感器的重要环节之一。对此文中基于对角隐式龙格库塔法提出了一种新的拓展梯形数字积分算法。为提高新型数字积分算法的积分精度,采用复合积分并推导出了不同采样频率下的通用新型数字积分器的传递函数。由于新型数字积分器的传递函数中含有分数延迟项,因此采用FIR和IIR两种滤波算法对其进行仿真分析。MATLAB仿真结果表明,新型数字积分器在低频段的性能要优于梯形数字积分器,可为基于Rogowski线圈的电子式电流互感器的积分环节提供一种全新的设计方法。     

Output‐feedback model‐reference adaptive calibration for map‐based anti‐jerk control of electromechanical automotive clutches

It is well known that the map‐based control can reduce the computational burden of the automotive on‐board controller. This paper proposes an output‐feedback model‐reference adaptive control algorithm to calibrate the map‐based anti‐jerk controller for electromechanical clutch engagement. The algorithm can be used to adaptively construct a data‐driven fuzzy rule base without resorting to manual tuning, so that it can overcome the problem of conventional knowledge‐based fuzzy logic design, which involves strenuous parameter‐tuning work in the construction of calibration maps. To accurately define the consequent of each fuzzy rule for anti‐jerk control, an output feedback law for computing the reference trajectory of clutch engagement is developed to eliminate the discontinuous slip‐stick transition, whereas an adaptive controller is designed to track the reference trajectory and compensate the nonlinearity. The convergence of the proposed output‐feedback model‐reference adaptive control algorithm is analyzed. Simulation results indicate that the proposed method can successfully reduce the excessive vehicle jerk and frictional energy dissipation during clutch engagement as compared with the conventional knowledge‐based fuzzy logic controller without fine tuning.     

电力系统稳定计算隐式积分交替求解

本文介绍一种基于微分方程隐式积分梯形公式的电力系统稳定计算隐式积分交替求解算法。该算法具有数值稳定性好、可采用较大积分步长、能够适应较长过程动态稳定模拟计算的特点，并具有显式积分编程简单可靠、便于扩展的优点。     

基于FPGA的高频电力电子装置快速实时仿真数值算法

实时仿真有助于实现工业分布式控制,优化生产过程并实现柔性生产.现场可编程门阵列FPGA(field programmable gate array)凭借高速并行的特点,在实时仿真方面取得了广泛的应用.针对高频动作的电力电子开关器件,当利用变步长算法解决开关动作时刻的偏移问题时,会导致仿真结果出现发散现象,且该算法延长了...     

一种基波串联谐振式混合型有源滤波器

提出一种基波串联谐振式混合型有源滤波器,利用大容量无源滤波器实现谐波抑制和无功补偿;采用有源滤波器改善系统滤波效果并阻尼无源滤波器与系统阻抗之间的串、并联谐振。在介绍该混合型有源滤波器的拓扑结构和主要特点的基础上,分析基于检测电网电流控制策略时的工作原理;研究谐波参考信号的产生及其跟踪控制算法;讨论基于DSP的数字化控制器实现问题。相关实验结果及工程应用效果均证明该基波串联谐振式混合型有源滤波器对于同时进行谐波抑制和无功补偿的可行性。     

A CMOS voltage regulator for passive RFID tag ICs

A low‐power voltage regulator for passive RFID tag ICs is proposed in this paper. It consists of a self‐biased mutually compensated voltage reference, a low dropout (LDO) voltage regulation circuit and a power‐on‐reset (POR) circuit. It is fabricated in a commercial 0.18?µm CMOS technology and applied to a passive UHF RFID tag IC. The total quiescent current is 700 nA under a 1.8‐V supply. The output voltage of the regulator is 1.45 V with load capability of 50 µA. The temperature coefficients of the voltage reference and the output voltage are only 9 and 43 ppm/^°C, respectively. A POR signal with width pulse of 150 ns is generated for the digital part in the tag IC. Copyright © 2010 John Wiley & Sons, Ltd.