According to the characteristics of single-phase circuits and demand of using active filter for real-time detecting harmonic and reactive currents, a detecting method based on Fryze＇s power definition is proposed. Th...According to the characteristics of single-phase circuits and demand of using active filter for real-time detecting harmonic and reactive currents, a detecting method based on Fryze＇s power definition is proposed. The results of theoretical analysis and simula- tion show that the proposed method is effective in realtime detecting of instantaneous harmonic and reactive currents in single-phase circuits. When only detecting the total reactive currents, this method does not need a phase-locked loop circuit, and it also can be used in some special applications to provide different compensations on the ground of different requirements of electric network. Compared with the other methods based on the theory of instantaneous reactive power, this method is simple and easy to realize.展开更多
Due to the components at twice the fundamental frequency of output voltage in the instantaneous output power of a two-stage single-phase inverter(TSI),the second harmonic current(SHC)is generated in the frontend dc-dc...Due to the components at twice the fundamental frequency of output voltage in the instantaneous output power of a two-stage single-phase inverter(TSI),the second harmonic current(SHC)is generated in the frontend dc-dc converter(FDC).To reduce the SHC,optimizing the control strategy of the FDC is an effective and costless approach.Fromthe view of visual impedance,this paper conducts an intensive study on the SHC reduction strategies.Origin of the SHC is illustrated first.Then,the equivalent circuit models of the FDC under different control strategies are proposed to analyse the SHC propagation characteristic.The derived model can offer a better insight into how the inductor SHC is affected by the control parameters.According to the derived models,a synthesis of different control strategies is presented and the relevant parameters are listed for control design to achieve better suppression effect.The benefits and limitations of these control strategies are also discussed.Based on the proposed equivalent circuit models,several optimization methods are proposed to enhance the effect.A 1500 VA TSI prototype is built and simulated on MATLAB/Simulink,verifying the effectiveness of the proposed optimization methods.This paper is aimed to provide a guideline for the control design and control optimization of the TSIs.展开更多
针对非理想电网电压条件下传统谐波检测方法表现出的性能不足问题,提出了一种基于改进同步锁相环(SRF-PLL)和滑动平均滤波器(Moving Average Filter,MAF)的d-q谐波电流检测法,应用于并联型有源电力滤波器。在SRF-PLL中通过对电网电压dq...针对非理想电网电压条件下传统谐波检测方法表现出的性能不足问题,提出了一种基于改进同步锁相环(SRF-PLL)和滑动平均滤波器(Moving Average Filter,MAF)的d-q谐波电流检测法,应用于并联型有源电力滤波器。在SRF-PLL中通过对电网电压dq轴分量做线性变换,消除了电压跌落瞬时峰值变化对锁相环的影响,加入MAF环节滤除电压畸变造成的波动;另一方面为了避免低通滤波器(LPF)固有的延时影响,用MAF替代传统d-q谐波检测法中的LPF。通过MATLAB/Simulink仿真分析验证,在电网电压发生跌落和畸变等非理想电网条件下使用改进后的谐波检测算法,可以实现谐波电流的准确检测,经补偿后电流畸变率控制在3%以下,达到了理想电网电压条件下的补偿效果。展开更多
电网阻抗特性不稳定导致谐波传播路径复杂化,传统检测方法难以区分背景谐波与本地谐波;同时,电压波动与频率偏移会掩盖真实的谐波特征,使得低频间谐波与高频噪声的分离变得困难,为此,提出弱电网下低压电网谐波高精度检测研究方法。通过M...电网阻抗特性不稳定导致谐波传播路径复杂化,传统检测方法难以区分背景谐波与本地谐波;同时,电压波动与频率偏移会掩盖真实的谐波特征,使得低频间谐波与高频噪声的分离变得困难,为此,提出弱电网下低压电网谐波高精度检测研究方法。通过Mallat快速多尺度框架将信号逐层映射至不同频带空间,获取子频带信号。引入集合经验模态分解(Ensemble Empirical Mode Decomposition,EEMD)算法分解子频带信号,提取出表征局部本征振荡特性的多阶IMF分量,避免虚假分量和模态混叠,准确提取基波与高次谐波。对固有模态函数(Intrinsic Mode Function,IMF)分量实施希尔伯特(Hilbert)变换,获取各IMF分量的瞬时参数,刻画谐波时变特性。并基于这些特性,从IMF分量中提取出基波分量,并计算得到总谐波分量。实验表明,在谐波点数在400~1200时,该方法的谐波幅值相对误差(Relative Error of Harmonic Amplitude,REHA)和谐波相位角均方根误差(Root Mean Squre Error of PhaseAngle,RMSE-PA)相较于对比方法最高分别降低32.5%、27.6%,说明该方法可精准捕捉谐波电流的动态变化及峰值时刻。且峰值位置吻合度达98.5%,能够实现弱电网下低压电网谐波高精度检测,对基波电流和谐波电流完成有效跟踪检测。展开更多
有源电力滤波器(Active Power Filter, APF)是一种具备动态谐波抑制和无功补偿功能的新型电力电子装置,其性能优劣与所采用的拓扑结构、谐波电流检测技术和电流追踪控制方法等密切相关。为了推广在高压大容量下APF的控制技术,拓宽其应...有源电力滤波器(Active Power Filter, APF)是一种具备动态谐波抑制和无功补偿功能的新型电力电子装置,其性能优劣与所采用的拓扑结构、谐波电流检测技术和电流追踪控制方法等密切相关。为了推广在高压大容量下APF的控制技术,拓宽其应用范围,综述了国内外APF研究现状,分类整理了APF拓扑结构。归纳总结了APF的谐波检测方法和电流跟踪控制技术,综合对比了各种方法的优缺点,并从多个角度阐述了当前所存在的问题。最后展望了APF相关技术的研究方向。展开更多
该文提出了一种电力基波频率和相位的高精度数字化实时检测方法,提出了基于高精度基波相频实时检测的有源电力滤波器谐波和无功电流的检测方法。相位检测是基于三角函数正交性及自适应滤波的原理构造了相位跟踪的闭环控制回路,结合延时...该文提出了一种电力基波频率和相位的高精度数字化实时检测方法,提出了基于高精度基波相频实时检测的有源电力滤波器谐波和无功电流的检测方法。相位检测是基于三角函数正交性及自适应滤波的原理构造了相位跟踪的闭环控制回路,结合延时反馈及变参数 PI 控制技术,使初相跟踪检测的精度达到(10-4)o^(10-10)o的数量级;基波频率的测量是基于初相跟踪检测控制系统的基础之上,求取稳态时初相修正量的时间变化率,即可作为频率跟踪的反馈。在有源电力滤波器中,利用该方法可以求取电压和电流的基波相位频率和相应基波的单位正弦函数,基波幅值用滑窗傅立叶变换的方法求得,从而方便精确地检测出有功和谐波电流。仿真与实验结果证明了所提方法的正确性和有效性。展开更多
文摘According to the characteristics of single-phase circuits and demand of using active filter for real-time detecting harmonic and reactive currents, a detecting method based on Fryze＇s power definition is proposed. The results of theoretical analysis and simula- tion show that the proposed method is effective in realtime detecting of instantaneous harmonic and reactive currents in single-phase circuits. When only detecting the total reactive currents, this method does not need a phase-locked loop circuit, and it also can be used in some special applications to provide different compensations on the ground of different requirements of electric network. Compared with the other methods based on the theory of instantaneous reactive power, this method is simple and easy to realize.
基金This work was supported in part by the Natural Science Foundation of Jiangsu Province under Grant BK20200969(L.Z.,http://std.jiangsu.gov.cn/).
文摘Due to the components at twice the fundamental frequency of output voltage in the instantaneous output power of a two-stage single-phase inverter(TSI),the second harmonic current(SHC)is generated in the frontend dc-dc converter(FDC).To reduce the SHC,optimizing the control strategy of the FDC is an effective and costless approach.Fromthe view of visual impedance,this paper conducts an intensive study on the SHC reduction strategies.Origin of the SHC is illustrated first.Then,the equivalent circuit models of the FDC under different control strategies are proposed to analyse the SHC propagation characteristic.The derived model can offer a better insight into how the inductor SHC is affected by the control parameters.According to the derived models,a synthesis of different control strategies is presented and the relevant parameters are listed for control design to achieve better suppression effect.The benefits and limitations of these control strategies are also discussed.Based on the proposed equivalent circuit models,several optimization methods are proposed to enhance the effect.A 1500 VA TSI prototype is built and simulated on MATLAB/Simulink,verifying the effectiveness of the proposed optimization methods.This paper is aimed to provide a guideline for the control design and control optimization of the TSIs.
文摘针对非理想电网电压条件下传统谐波检测方法表现出的性能不足问题,提出了一种基于改进同步锁相环(SRF-PLL)和滑动平均滤波器(Moving Average Filter,MAF)的d-q谐波电流检测法,应用于并联型有源电力滤波器。在SRF-PLL中通过对电网电压dq轴分量做线性变换,消除了电压跌落瞬时峰值变化对锁相环的影响,加入MAF环节滤除电压畸变造成的波动;另一方面为了避免低通滤波器(LPF)固有的延时影响,用MAF替代传统d-q谐波检测法中的LPF。通过MATLAB/Simulink仿真分析验证,在电网电压发生跌落和畸变等非理想电网条件下使用改进后的谐波检测算法,可以实现谐波电流的准确检测,经补偿后电流畸变率控制在3%以下,达到了理想电网电压条件下的补偿效果。
文摘电网阻抗特性不稳定导致谐波传播路径复杂化,传统检测方法难以区分背景谐波与本地谐波;同时,电压波动与频率偏移会掩盖真实的谐波特征,使得低频间谐波与高频噪声的分离变得困难,为此,提出弱电网下低压电网谐波高精度检测研究方法。通过Mallat快速多尺度框架将信号逐层映射至不同频带空间,获取子频带信号。引入集合经验模态分解(Ensemble Empirical Mode Decomposition,EEMD)算法分解子频带信号,提取出表征局部本征振荡特性的多阶IMF分量,避免虚假分量和模态混叠,准确提取基波与高次谐波。对固有模态函数(Intrinsic Mode Function,IMF)分量实施希尔伯特(Hilbert)变换,获取各IMF分量的瞬时参数,刻画谐波时变特性。并基于这些特性,从IMF分量中提取出基波分量,并计算得到总谐波分量。实验表明,在谐波点数在400~1200时,该方法的谐波幅值相对误差(Relative Error of Harmonic Amplitude,REHA)和谐波相位角均方根误差(Root Mean Squre Error of PhaseAngle,RMSE-PA)相较于对比方法最高分别降低32.5%、27.6%,说明该方法可精准捕捉谐波电流的动态变化及峰值时刻。且峰值位置吻合度达98.5%,能够实现弱电网下低压电网谐波高精度检测,对基波电流和谐波电流完成有效跟踪检测。
文摘有源电力滤波器(Active Power Filter, APF)是一种具备动态谐波抑制和无功补偿功能的新型电力电子装置,其性能优劣与所采用的拓扑结构、谐波电流检测技术和电流追踪控制方法等密切相关。为了推广在高压大容量下APF的控制技术,拓宽其应用范围,综述了国内外APF研究现状,分类整理了APF拓扑结构。归纳总结了APF的谐波检测方法和电流跟踪控制技术,综合对比了各种方法的优缺点,并从多个角度阐述了当前所存在的问题。最后展望了APF相关技术的研究方向。
文摘该文提出了一种电力基波频率和相位的高精度数字化实时检测方法,提出了基于高精度基波相频实时检测的有源电力滤波器谐波和无功电流的检测方法。相位检测是基于三角函数正交性及自适应滤波的原理构造了相位跟踪的闭环控制回路,结合延时反馈及变参数 PI 控制技术,使初相跟踪检测的精度达到(10-4)o^(10-10)o的数量级;基波频率的测量是基于初相跟踪检测控制系统的基础之上,求取稳态时初相修正量的时间变化率,即可作为频率跟踪的反馈。在有源电力滤波器中,利用该方法可以求取电压和电流的基波相位频率和相应基波的单位正弦函数,基波幅值用滑窗傅立叶变换的方法求得,从而方便精确地检测出有功和谐波电流。仿真与实验结果证明了所提方法的正确性和有效性。
