Improvement of DEA performance against harmonic distortion

This paper presents a filtering application to improve the behavior of the Differential Equation Algorithm (DEA) against harmonic distortion in transmission and distribution power systems. The proposed filter is based on Fast Fourier Transform (FFT) techniques during steady-state conditions. The voltage and current continuous-time equations are also considered, in fault conditions, to estimate the fundamental component waveforms of voltage and current. Simulations results show the singularities problems of DEA algorithm against harmonic distortion and the accurate operation achieved within 0.32 cycles using this filtering application.     

Real-time measurement of power disturbances: Part 2. Implementation and evaluation of the novel complex filter/recursive algorithm

The novel complex filter/recursive algorithm, which are proposed in part 1 of the two-part series, is an improved signal processing technique that can accurately and continuously measure the instantaneous electrical quantities such as the amplitude, phase angle, frequency and power of the fundamental and harmonic components even during power disturbances. This paper, which is part 2 of the series, focuses on the ways to implement the proposed method for real-time applications. Further, the effectiveness and superiority of the proposed method over the well-known Fourier Algorithm (FA) and the Morlet wavelet-based Continuous Wavelet Transform (CWT) are also ascertained in this paper using both simulated and practical power disturbance waveforms.     

Real time measurement of power disturbances: Part 1. Survey and a novel complex filter approach

The accurate and real time measurement of power disturbance is a key element of protection, control, fault diagnosis, power quality monitoring and power metering in electric power systems. This paper proposes three criteria for selecting or developing an appropriate measurement technique and, based on these criteria, the performance of the measurement techniques in common use or newly developed are analysed. A novel complex filter and the associated recursive algorithm are further presented in this paper, which achieve both high measurement accuracy in all service conditions and low computational complexity. The potential applications of the proposed method are also addressed briefly, its effectiveness and superiority are ascertained in Part 2 of the series using both simulated and practical power disturbance waveforms.     

基于递推DFT算法数字滤波器的研制

推导出递推DFT算法，并采用该算法实现了电力系统谐波与基波的分离，仿真和试验表明该算法具有计算量少、实现简单、滤波效果良好的优点，可用于基于交流采样的电力系统滤波和数据采集系统。     

降低逆变器容量的混合有源电力滤波器控制方式

针对一种降低逆变器容量的混合有源电力滤波器,详细介绍了其在三种控制方式下的工作原理、性能特点和等效电路,搭建了容量为10kV.A的混合有源电力滤波器实验样机,并进行了三种控制方式的实验和分析.实验结果表明,采用复合控制方式,该结构中逆变器容量仅为整个滤波器容量的4.42%,而该滤波器投入后,电网电流总谐波畸变率从26.95%下降到4.25%,补偿效果良好且优于其他两种控制方式.     

新型注入式混合有源滤波器的数学模型及电流控制方法

有源滤波器的数学模型是进行稳态、动态及电流控制方法等方面研究的基础,本文以新型注入式混合有源滤波器为例,详尽分析了建立其数学模型的方法,结合双滞环电流控制方法响应速度快、开关损耗低的优点和递推积分PI控制方法无稳态误差的特点,提出了一种新的复合型电流控制方法.通过仿真,从跟踪速度、控制精度和开关次数三个方面,将新的控制方法与双滞环电流控制方法以及单一的递推积分PI控制方法进行了对比研究.实验结果也证明了该数学模型的正确性和复合型电流控制方法的有效性.     

有源电力滤波器的谐波检测研究

目前电网的谐波污染越来越严重,有源电力滤波器由于能实时抑制谐波,所以得到外界广泛关注。谐波电流检测的好坏对有源电力滤波器的性能有很大的影响,所以,本文就目前的几种谐波检测方法:基于傅里叶变换、基于瞬时无功功率理论、基于同步参考坐标系原理、基于频域分析的模拟带通或者带阻、基于采样保持原理、基于Fryze时域分析、基于小波变换、基于Prony/Kalman估计、基于神经网络的谐波检测法/自适应滤波理论谐波检测法进行了概括和比较分析。     

A PLL-Based Multirate Structure for Time-Varying Power Systems Harmonic/Interharmonic Estimation

This paper describes a phase-locked-loop (PLL)-based power systems harmonic estimation algorithm, which uses an analysis filter bank and multirate processing. The filter bank is composed of bandpass filters. The initial center frequency of each filter is purposely chosen to be equal to harmonic frequencies. However, an adaptation strategy makes it possible to track time-varying frequencies as well as interharmonic components. A downsampler device follows the filtering stage, reducing the computational burden, especially because undersampling operations are performed. Finally, the last stage is composed of a PLL estimator which provides estimates for amplitude, phase, and frequency of the input signal. The proposed method improves the accuracy, computational effort, and convergence time of the previous harmonic estimator based on cascade PLL configuration.     

Adaptive noise reduction using numerically stable fast recursive least squares algorithm

This paper is concerned with adaptive noise reduction based on the fast recursive least squares (FRLS) algorithm. It is well known that the fast recursive least squares (FRLS) algorithm suffers from numerical instability when operating under the effects of finite precision arithmetic. Several numerical solutions of stabilization were proposed in the case of stationary signals. In this work a new version of a numerically stable FRLS algorithm (NS‐FRLS) is proposed. The stability characteristics of this new stabilized algorithm are analysed. The analysis is based on a linear model for the errors in the states of the adaptive filter. Experimental results confirm the merits of adaptive filtering with the NS‐FRLS algorithm over optimum filtering using the solution provided by Wiener–Hopf equations. Copyright © 2006 John Wiley & Sons, Ltd.     

基于递推积分PI的混合型有源电力滤波器电流控制

在采用混合型有源电力滤波器消除谐波时，由于滤波器的检测精度、指令电流计算延时和输出滤波器的相移等因数的影响，滤波效果不够理想，针对被控量是以20ms为周期的电流，文中提出了应用于混合型有源滤波器的递推积分PI控制算法，并且引入了参考电流模糊加权前馈控制。该控制方法有效地提高系统的目标跟随特性、抗干扰性和鲁棒性，并且具有计算量小、容易工程实现的特点，实验结果证明了所提出的控制方法的可行性。所提出的递推积分H控制算法还可以对周期性的被控量实现无静差控制，如交流电机的闭环控制。     

一种新型混合型大功率有源电力滤波器电流控制方法

在采用混合型大功率有源电力滤波器消除谐波时,由于滤波器的检测精度、指令电流计算延时和输出滤波器的相移等因数的影响,滤波效果不够理想,针对这一问题,笔者提出了应用于混合型大功率有源滤波器的模糊递推积分PI控制算法。该方法能有效地提高系统的目标跟随特性、抗干扰性和鲁棒性,并且具有计算量小、工程容易实现的特点。实验结果证明了所提出的控制方法的可行性。所提出的模糊递推积分PI控制算法还可以对周期性的被控量实现无静差控制,如交流电机的闭环控制。     

A reiterative DFT to damp decaying DC and subsynchronous frequency components in fault current

This work presents a reiterative discrete Fourier transform (DFT) algorithm for fault current filtering. First, the short-windows DFT (SWDFT)-based mimic filter is developed to damp the measurement. Then, a reiterative scheme is proposed to reconstruct the damped measurement for further damping. The proposed algorithm can sufficiently damp the decaying dc as well as the subsynchronous frequency components. Thus, the proposed algorithm is appropriate to the filtering design on both the conventional and series-compensated transmission lines. Meanwhile, the recursive form is developed to reduce the computational burden. The simulation results illustrate that the algorithm significantly reduces the time to obtain the accurate fundamental phasor and that it has a better performance than the conventional DFT algorithm.     

并联型有源电力滤波器直流侧电压控制策略的研究

在研究了PI控制方法控制方法的基础上,提出了对有源电力滤波器直流侧电压实现模糊递推PI控制的方法,设计了模糊控制规则,详细介绍了模糊递推PI控制方法的控制原理,并且针对PI控制方法和模糊递推PI控制方法采用Matlab/Simunlink仿真软件对直流侧电压进行仿真分析。仿真结果表明,模糊递推PI控制方法在系统稳定以及负载突变时比PI控制方法能够更加有效地消除稳态误差,使有源电力滤波器直流侧电压实现精确跟踪,从而提高滤波器的滤波效果。     

Adaptive measuring algorithm suppressing a decaying DC component for digital protective relays

This paper presents a new adaptive phasor estimation algorithm for digital protective relaying. The algorithm is completely immune to an exponentially decaying dc component regardless of its initial magnitude and time constant. The algorithm is primarily intended for current signals and improves both magnitude and impedance measurements. The new technique is based on the recursive full-period Fourier filter with a separate adaptive function allowing for thorough rejection of the dc signal component. The comparative analysis of the algorithm, both analytical and by simulation, is included. The presented algorithm outperforms known measuring techniques including the digital mimic filtering broadly used in today's relays.     

并网逆变器LCL滤波器的参数优化设计

LCL型滤波器因具有更优的高频谐波衰减性和滤波效果被广泛应用于并网逆变器中,但其参数设计较为复杂。提出了一种新的LCL型滤波器参数优化设计方案,建立以纹波电流最小化、谐波衰减最大化和功率损耗最小化的多个目标优化设计模型。运用熵值权重法转换为单目标优化模型并利用遗传算法对优化模型求解。在MATLAB/Simulink中搭建基于LCL滤波器的并网逆变器仿真模型,验证了该优化方案的适用性。与现有方法相比,文中的优化方法在保证滤波效果的前提下,具有更好的谐波衰减性能,抑制纹波的能力及更小的功率损耗。     

Recursive implementation of MUSIC algorithm to minimize power system disturbances

This paper exhibits new recursive implementation of the root-MUSIC algorithm in power system applications in order to extract the instantaneous power disturbances, which emanate from the arc furnace. The MUSIC algorithm is selected because it has an outstanding capability to estimate and track the frequencies of all types of distortion such as harmonics and interharmonics. The utilized algorithm has been newly developed so as to recursively track the instantaneous disturbances in the arc furnace current and consequently mitigate them. The suggested development of the recursive root-MUSIC is compared with the ESPRIT in order to prove that the adopted technique outperforms the high-resolution common techniques in a noisy or non-noisy environment. The instantaneous disturbance is formed by an innovative formulation of the recursive notch filter. Moreover, the experimental results are given to prove the practicality of the proposed concepts and techniques.     

用于去除心电信号中工频干扰数字滤波技术

文中讨论了去除心电信号工频干扰的几种数字滤波器设计方法,从实用性角度对其滤波性能和实现方法进行比较。实验比较。实验表明,简单整系数滤波器和自适应滤波器对于心电中工频干扰的滤除具有较好的综合性能。     

基于小波分析和智能补偿的三相电力混合滤波算法

在分析传统电力滤波方法的基础上,针对检测电网侧谐波分量和负荷侧谐波分量的复合滤波控制方法无法抑制电网参数对滤波和无功补偿影响的不足,引入智能补偿因子。提出基于小波分析和智能补偿的三相电力混合滤波算法。利用小波算法检测电网电流和载荷电流谐波分量,该结果作为样本利用遗传神经网络进行训练,预测当前电网参数对滤波效果的影响程度,计算智能补偿因子,对混合滤波控制进行补偿。实验结果说明,基于小波分析和智能算法对混合滤波控制进行补偿,是提高其动态性和降低谐波量的有效途径。     

小角度法结合复合形态滤波器的单相电压跌落检测方法

针对当前电网电压跌落频繁和传统电压跌落检测方法准确性和快速性不足的问题,提出一种延迟小角度法结合复合形态滤波器的单相电压跌落快速检测方法。详细论述了延迟小角度法和复合形态滤波器的工作原理,先使用复合形态滤波器对电力信号进行初次滤波,再通过延迟小角度的方法构造虚拟三相电压,对三相电压进行Park变换并用直线形态滤波器滤除残余的谐波分量。仿真分析了复合形态滤波器的滤波效果,对受到复杂噪声和谐波干扰的电压跌落波形进行了仿真测试,并搭建了实际的电压跌落硬件模型且使用采集到的数据再次对算法进行了验证,结果都表明该方法能够快速准确地检测出电压跌落起止时刻、深度和相位。     

有源电力滤波器LCR型输出滤波器参数优化设计

为了滤除高频开关产生的谐波电流,提出用二阶LCR型滤波器滤除纹波电流。建立了二阶LCR型滤波器的数学优化模型。通过MATLAB仿真,分析了参数变化时的滤波性能及适用范围的特点,并用混合遗传算法对其优化设计,研究了逆变侧电感变化时有源电力滤波器输出电流和逆变侧电压的bode图,并确定出逆变侧的电感值。针对80 kV.A有源电力滤波器样机进行了实验研究,MATLAB仿真和实验结果表明,所提优化算法具有较快的收敛速度,优化结果更靠近全局最优;优化后LCR型输出滤波器在开关谐波高频段的滤波性能显著增加,有效地抑制了开关谐波。