Three-phase four-wire shunt active power filter based on the SOGI filter and Lyapunov function for DC bus control

The three-phase four-wire shunt active power filter (SAPF) was developed to suppress the harmonic currents generated by nonlinear loads, and for the compensation of unbalanced nonlinear load currents, reactive power, and the harmonic neutral current. In this work, we consider instantaneous reactive power theory (PQ theory) for reference current identification based on the following two algorithms: the classic low-pass filter (LPF) and the second-order generalized integrator (SOGI) filter. Furthermore, since an important process in SAPF control is the regulation of the DC bus voltage at the capacitor, a new controller based on the Lyapunov function is also proposed. A complete simulation of the resultant active filtering system confirms its validity, which uses the SOGI filter to extract the reference currents from the distorted line currents, compared with the traditional PQ theory based on LPF. In addition, the simulation performed also demonstrates the superiority of the proposed approach, for DC bus voltage control based on the Lyapunov function, compared with the traditional proportional-integral (PI) controller. Both novel approaches contribute towards an improvement in the overall performance of the system, which consists of a small rise and settling time, a very low or nonexistent overshoot, and the minimization of the total harmonic distortion (THD).     

三电平APF谐波电流及中点电位平衡控制

针对三电平有源电力滤波器,提出一种基于带柔化输入的模型预测控制方法用于谐波补偿。同时,为避免直流侧中点电位的波动和偏移问题给系统稳定性带来的不利影响,采用基于平衡因子和简化SVPWM算法的中点电位平衡控制策略。模型预测控制方法根据实际有源电力滤波器控制系统设计电流预测模型,同时将预测输出与实际输出的偏差及时反馈,结合滚动优化,使有源电力滤波器的补偿电流快速跟踪参考值。直流侧母线电压控制采用简化三电平SVPWM算法,简化了算法同时保证了中点电位平衡。建立了APF预测电流控制的等效模型,并进行了仿真验证。所提方法有效柔化电流输入从而减小超调,较传统预测控制方法更为稳定,减少了谐波含量和改善了补偿精度,并保证了直流母线电压的稳定和中点电位快速平衡。仿真结果验证了所提控制策略的有效性与可行性。     

医疗建筑谐波分析及治理措施

分析医疗建筑中产生谐波的常见医疗设备的特点;实测医疗设备的谐波数据;提出医疗建筑的谐波治理措施。     

Bayesian changepoint and time-varying parameter learning in regime switching volatility models

This paper proposes a combined state and piecewise time-varying parameter learning technique in regime switching volatility models using multiple changepoint detection. This approach is a Sequential Monte Carlo method for estimating GARCH & EGARCH based volatility models with an unknown number of changepoints. Modern auxiliary particle filtering techniques are used to calculate the posterior densities and online forecasts. This approach also automatically deals with the common ancestral path dependence problem faced in these type volatility models. The model is tested on Borsa Istanbul (BIST) formerly known as Istanbul Stock Exchange (ISE) market data using daily log returns. A full structural changepoint specification is defined in which all parameters of the conditional variance of the volatility models are dynamic. Finally, it is shown with simulation experiments that the proposed approach partitions the series into several regimes and learns the parameters of each regime's volatility model in parallel with the multiple changepoint detection process.     

Realization of active power filter based on indirect current control algorithm using Xilinx system generator for harmonic elimination

Realization of active power filter with Model Based Design approach is presented in this paper. The approach adopts different modeling platforms as well as selection of proper hardware for step wise verification and testing. The active power filter model is developed using the Matlab/Simulink platform for single phase. The efficiency of the control algorithms such as synchronous detection method and indirect current control for active power filter is analyzed. Efficient control algorithm is developed by Xilinx system generator which is incorporated into Simulink as Xilinx tool box. Xilinx system generator provides a virtual platform for easy and effective design of the required system models in FPGA (field programmable gate array) design environments. Optimized automatic VHDL code is generated for the control algorithm which is simulated using ISE 13.2 for the generation of switching signals for the control of IGBTs of the active power filter. Suitable compensation signal is generated from the active power filter for the better elimination harmonics to improve the power quality. THD is reduced to a considered value which is able to satisfy the limits of the IEEE standard.     

四桥臂有源电力滤波器三维空间矢量调制技术的研究

三相四桥臂拓扑结构的有源电力滤波器（APF）不但能抑制谐波电流,也能补偿三相不平衡。在此介绍了系统的拓扑结构;通过对四桥臂电压型变换器进行建模分析,得到了APF的控制策略;详细分析了APF的三维空间矢量脉宽调制法（3D-SVM）;最后搭建了一台实验样机。实验结果验证了控制策略和调制方法的正确性和有效性。     

并联型有源滤波器空间矢量预测电流控制

为了提高有源滤波器(APF)的电流跟踪性能,本文采用电压空间矢量预测电流控制方法。该方法在当前采样时刻预测下一采样时刻的指令电流,计算出APF在下一采样时刻的输出端参考电压,再利用电压空间矢量调制得出控制开关信号,以达到电流跟踪控制目的。仿真实验表明,该方法具有更好的电流控制效果。     

基于无差拍控制的三电平有源滤波器研究

文章以二极管箝位型三电平有源滤波器为研究对象,详细推导了该三电平有源滤波系统在abc坐标系下与dq坐标系下的数学模型：阐述了无差拍控制原理,并构建重复预测型观测器,对指令电流进行预测,改善了系统的控制效果;采用改进型主动平衡因子法,预测直流侧中点电荷的变化趋势,控制直流侧中点电位平衡。仿真验证了该有源滤波系统性能良好。     

并联混合型有源电力滤波器中无源滤波器设计与优化

介绍了一种针对中等功率非线性设备网侧谐波补偿的分布式并联混合型有源电力滤波器,并对其中无源滤波器的优化设计问题进行了重点研究,提出了一种实用的无源滤波器优化设计方法;详细分析了无源滤波器参数对有源模块开关管耐压、滤波支路电流的影响并推导了时域解析表达式;基于此优化设计方法,针对整流性负载进行了滤波器参数设计,相比传统的经验设计方法,在相同有源容量情况下,采用新的优化方法设计无源参数,滤波器滤波效果明显改善。仿真及实验结果验证了优化设计方法的有效性。