基于DSP的一种三相电路谐波电流检测算法

为能用数字信号处理器(DSP)实现三相电路的谐波电流检测,从基于瞬时无功理论的一种谐波电流检测方法出发,分别讨论了三相电流中谐波正序和谐波负序分量检测的数字方法,由此得出了一种实时的谐波电流检测算法.该算法能准确地检测出三相电流中的谐波正序和谐波负序分量.当有源电力滤波器(APF)等装置的谐波电流检测电路采用该算法时,可根据需要适时调整DSP程序来形成不同的参考电流,以便更好地满足APF的不同补偿要求.仿真和实验研究结果表明了该算法的有效性和可行性.     

三相桥式整流电路谐波电流检测分析与仿真

本文针对电网中最典型的谐波源——三相桥式整流电路,研究基于瞬时无功功率理论的谐波电流检测方法。利用Matlab/Simulink仿真软件,搭建谐波电流检测的仿真模型,进行仿真分析。通过观察得到的仿真波形,验证＂ip-iq＂法在谐波电流检测中的实际效果,从而为治理电网谐波,进行无功补偿,提供简便的分析手段。     

基于迭代算法的有源电力滤波器谐波电流实时检测新方法

目前，已经提出了多种有源电力滤波器谐波及无功电流检测方法，尽管这些方法各有特点，但都存在着难以克服的问题，如计算量大，实时性差，检测精度不高等。文章在负载电流分析的基础上，提出了一种基于迭代算法的有源电力滤波器谐波电流实时检测方法，该方法具有计算量非常小，实时性好，检测精度高等特点。理论分析与仿真研究证实了该方法的正确性。     

Analysis of Nonlinearities in Superconducting Microstrip Straight Bends; FDTD Method in Comparison with Nonlinear Circuit Modeling

This paper presents the prediction of nonlinearities in the superconducting microstrip straight bends in microwave frequencies based on two different methods; FDTD simulation as a numerical approach, and nonlinear circuit modeling as an analytical method. In the FDTD method, the superconducting microstrip structures are simulated with London’s equations. In the simulation, the penetration depth and normal conducting coefficient are considered as functions of current density of superconductor. To simulate the thin strip of superconductor, a non-uniform mesh has been used. For the nonlinear circuit modeling, we use distributed RLGC parameters for superconducting microstrip transmission lines. These parameters are considered as functions of the current distribution. This yields an equivalent nonlinear circuit model for bends. The final equivalent nonlinear circuit is analyzed using the harmonic balance (HB) method. Different straight bend structures have been considered and the two methods’ results are compared.     

直流大电流比较仪谐波影响问题的研究

本提出了在谐波影响下直流大电流比较仪的等效电路模型及计算方法,通过仿真给出了该模型的频率特性,通过试验数据与仿真结果的比较证实了电路模型的可行性,对研究直流大电流比较仪和电流互感器的谐波影响具有指导意义。     

Renovating the excitation circuit of a conventional welding converter

This paper presents two different new excitation current supplies based on power electronics for an existing conventional welding converter. The proposed circuits are simulated using Lab-VIEW 1200 AI and a PC based system. In the expressions for winding currents the dynamic inductances are used to take into account the saturation in the core of the winding. The experimental circuits are implemented and tested. The percentage peak-to-peak ripple currents are calculated for both simulation and experimental results and for both circuit configurations. The results are summarized in two tables for comparison.     

纯电动公交充电站谐波分析的模型方法

通过建立纯电动汽车高频充电机的一般等效模型的方法,研究了大功率高频充电机产生的电流谐波的构成以及影响电流谐波含量的主要因素,在此基础上建立了分析纯电动公交充电站谐波电流污染供电网和用电设备问题的仿真模型,并用此模型进行了基于纯电动公交运行特点和纯电动汽车蓄电池参数的充电站谐波电流仿真分析.仿真分析的结果可用于纯电动公交充电站谐波污染情况的预测分析,并作为选择谐波抑制设备的依据.     

A passive auxiliary circuit with interphase transformer applied in 12-pulse converters to provide clean power utility interface

This paper proposes a passive auxiliary circuit which can be added to an interphase transformer (PAC + IPT) configuration to reduce the total harmonic distortion (THD) existing in 12-pulse diode rectifier converter systems at AC mains. The proposed PAC + IPT compensation method is a simple structure, with low power consumption and requires no extra DC power supply. We present the theoretical analysis of the proposed topology that lessens the total harmonic distortion (THD) and evaluate the dynamic simulation results on a 12-pulse converter system and a 3-kW laboratory prototype. Both the simulation and the experimental results show that the proposed PAC + IPT compensation method can improve the power quality and provide a clean power utility interface of AC line input currents for a conventional 12-pulse diode rectifier converter.     

Fault Diagnosis of Power Electronic Circuits Based on Adaptive Simulated Annealing Particle Swarm Optimization

In the field of energy conversion, the increasing attention on power electronic equipment is fault detection and diagnosis. A power electronic circuit is an essential part of a power electronic system. The state of its internal components affects the performance of the system. The stability and reliability of an energy system can be improved by studying the fault diagnosis of power electronic circuits. Therefore, an algorithm based on adaptive simulated annealing particle swarm optimization (ASAPSO) was used in the present study to optimize a backpropagation (BP) neural network employed for the online fault diagnosis of a power electronic circuit. We built a circuit simulation model in MATLAB to obtain its DC output voltage. Using Fourier analysis, we extracted fault features. These were normalized as training samples and input to an unoptimized BP neural network and BP neural networks optimized by particle swarm optimization (PSO) and the ASAPSO algorithm. The accuracy of fault diagnosis was compared for the three networks. The simulation results demonstrate that a BP neural network optimized with the ASAPSO algorithm has higher fault diagnosis accuracy, better reliability, and adaptability and can more effectively diagnose and locate faults in power electronic circuits.     

Improving the performance of hysteresis direct torque control of IPMSM using active filter topology

This paper describes an active filter topology to improve the performance of hysteresis direct torque control (HDTC) of interior permanent magnet synchronous motor (IPMSM). The filter topology consists of an active filter and two RLC filters, and is connected to the main power circuit through a 1:1 transformer. The active filter is characterized by detecting the harmonics in the motor phase voltages and injecting equivalent harmonic voltages to produce almost sinusoidal voltage waveform to the motor terminals. The active filter uses hysteresis voltage controller while the motor main circuit uses hysteresis direct torque control. The simulation results of this combined control structure show considerable torque ripple reduction in the steady state range and adequate dynamic torque performance as well as considerable harmonic voltage and EMI noise reduction.     

虚拟仪器技术在谐波检测系统中的应用研究

指出了电力系统中谐波问题的严重性,并就常见的电力系统谐波的分析方法及优缺点进行了概括。重点阐述了采用傅里叶变换的方法对谐波进行检测和分析的原理,对虚拟仪器技术的特点和优点并与传统仪器分析技术进行了初步对比。最后,给出了基于虚拟仪器技术的电力系统谐波检测和分析系统的软、硬件组成,并简要分析了该系统的运行结果。     

平衡式E/F类功率放大器的设计与实现

为了解决功率放大器设计过程中存在的效率低和输入/输出端回波损耗较大的问题,设计了一种工作频率为1.5 GHz的平衡式功率放大器。通过采用3 dB定向耦合器对射频信号进行分配及合成,大大降低了输入/输出端的驻波系数,并将逆F类功率放大器的谐波控制网络引入E类功率放大器的匹配电路中。使用ADS对晶体管进行负载牵引和源牵引,得到晶体管的输入/输出阻抗,同时结合晶体管的寄生参数,在输出匹配电路中对二次谐波、三次谐波分别进行开路和短路处理,且为了进一步提高功率放大器的工作性能,在输入电路结构中抑制了二次谐波。选用GaN HEMT器件CGH40010F晶体管,利用ADS软件进行电路仿真,并采用Rogers4350b高频板材制作该功率放大器的实际测试电路板。仿真优化和实测表明：在输入功率为28 dBm时,该功率放大器的输出功率为41.54 dBm,漏极效率为76.99%,功率附加效率（power additional efficiency,PAE）达到73.59%,输入/输出端驻波系数小于2,同时具有160 MHz的高效率带宽,且最大输出功率较单管功率放大器提高了3 dB。实测结果与仿真数据有一定的误差,但仍有较好的一致性,满足设计指标要求,验证了设计方法的可行性。该设计方法具有效率高和回波损耗低的优势,提高了功率放大器的设计效率,使它在当今高效绿色节能的射频微波通信系统中具有广阔的应用前景。     

谐波及无功分量实时检测的一种小波方法

从小波函数的带通性质出发,利用小波变换在不同尺度下对非正弦电流信号进行检测,由此得出了它的基波和谐波分量及其有效值. 通过重构基波分量与电源电压之间的相位差,求得了信号中的基波无功电流分量. 为说明所提出检测方法的有效性,进行了相应的仿真研究,并讨论了影响检测精度的因素.     

基于谱峭度的谐波模态检测方法

在旋转机械领域,周期激励的存在使运行模态分析中含有谐波模态。根据结构模态和谐波模态的谱峭度值的不同,该文提出了基于谱峭度的谐波模态辨识方法。首先,给出了谱峭度的定义及其无偏估计算法;其次,从理论上证明应用此方法不需要滤波处理,并提出了简单且易于实现的优化方法;然后,应用频域空间域分解算法分离出谐波模态去除其对结构模态的影响;最后,通过仿真及实验成功检测出了谐波模态并消除其影响,验证了方法的有效性和可靠性。     

3D modeling of electromagnets fed by alternating voltage sources

A method allowing 3D simulation of AC voltage driven electromagnets is described. Since the harmonic current in the exciting coil depends on the air gap width, the electromotive force in the windings has to be taken into account. A computation method based on the finite element method was developed in order to obtain the static attractive force characteristics of AC electromagnets used for circuit breakers. This method is based on nodal finite elements and loop equations of the electric circuit. Both magnetic field and electric circuit equations are solved simultaneously in the frequency domain. Computation results are compared with measurements on a 32-A contractor/circuit breaker     

Disturbing Load Identification in Power Systems: A Single-Point Time-Domain Method Based on IEEE 1459-2000

This paper presents a single-point method for the identification of prevailing disturbing loads in power systems for both single-phase and three-phase applications downstream or upstream from the metering section. It is based on the simultaneous measurement of three nonactive power quantities, which are based on the IEEE Std. 1459-2000 approach. The proposed method is only based on the separation of the fundamental components from the harmonic content of voltage and current; thus, it does not require any spectral analysis of the voltages and current. In this paper, the formulation of the proposed method and its time-domain implementation are described; moreover, some simulation results are presented and discussed, showing the effectiveness of the method both in the absence and in the presence of the measurement transducers.     

基于单矢量水听器弱信号值班检测系统

采用平均声强作为检测量,设计出一种基于单个矢量水听器的低功耗弱信号值班检测系统。针对矢量信号特有的 90°相移、指向性零点、相乘再积分、正负双极性等问题,设计了宽带全通 90°移相网络、双通道检测、1Bit模数混合乘法器、定时放电、绝对值检测等功能电路。系统设计中兼顾高增益、低功耗、稳定可靠等实际需要,并选用微功耗模拟器件。系统仿真研究显示,该系统作用距离超过 2km。初步设计制作的实验电路板,工作带宽达到1. 8kHz,工作电流 5mA,稳定可靠。     

谐波噪声下的试验模态分析

试验模态分析中通常使用平均方法处理由实验环境引起的随机噪声。当测试环境中含有周期噪声时,很难通过平均方法去除,在频响函数中会产生虚假共振峰,影响结构参数识别精度。该文提出了基于增强概率统计的谐波响应检测方法,将物理坐标下的响应信号变换到模态坐标中,并根据谐波信号的统计特性检测出谐波成分。提出了一种基于谐波分解与重构的谐波去除方法,用于消除谐波成分对结构参数识别的影响。通过平面刚架的仿真算例和GARTEUR飞机模型实测算例阐明了提出方法的实现过程,验证了其可靠性。     

A frequency‐dependent droop scheme for parallel control of ups inverters

Abstract

This paper presents a frequency‐dependent droop scheme for paralleling UPS inverters with no control interconnection, so the inverters can be tightly connected with the load. At the fundamental frequency, the reference voltage of the inverter is generated as a reactor connected between the inverter and the load. The intention is to control the real and reactive power sharing of inverters with the Q‐V and P‐ω droop scheme employed in the power system without needing a true transfer reactor. At the harmonic frequency, the reference voltage is generated as a resistor connected between the inverter and the load. The intention is that the load harmonic current can be shared equally and the voltage waveform distortion will be low. Two 1KVA single‐phase inverters are designed and implemented, some simulation and experimental results are provided for demonstrating the effectiveness of the proposed approach.     

Modeling of a carbon nanotube ultracapacitor

The modeling of carbon nanotube ultracapacitor (CNU) performance based on the simulation of electrolyte ion motion between the cathode and the anode is described. Using a molecular dynamics (MD) approach, the equilibrium positions of the electrode charges interacting through the Coulomb potential are determined, which in turn yield the equipotential surface and electric field associated with the capacitor. With an applied ac voltage, the current is computed based on the nanotube and electrolyte particle distribution and interaction, resulting in the frequency-dependent impedance Z(ω). From the current and impedance profiles, the Nyquist and cyclic voltammetry (CV) plots are then extracted. The results of these calculations compare well with existing experimental data. A lumped-element equivalent circuit for the CNU is proposed and the impedance computed from this circuit correlates well with the simulated and measured impedances.