当并联有源电力滤波器(Shunt Active Power Filter,SAPF)接入电网时相序错接,将导致锁相环无法正确锁相,不能正常进行谐波抑制与无功补偿。为了解决这一问题,文章分析了网侧电压相序对SAPF的影响,推导出同步旋转坐标系下的电压d轴与q轴...当并联有源电力滤波器(Shunt Active Power Filter,SAPF)接入电网时相序错接,将导致锁相环无法正确锁相,不能正常进行谐波抑制与无功补偿。为了解决这一问题,文章分析了网侧电压相序对SAPF的影响,推导出同步旋转坐标系下的电压d轴与q轴分量,提出了利用同步旋转坐标变换与滑窗平均滤波器由软件实现的相序检测方法。同时针对相序检测方案的性能进行了研究,得出滑窗滤波器窗口长度与相序判断阈值间的关系及判断SAPF网侧电压相序的判断原理。在获得了电网相序的基础上,设计了三相SAPF错序校正策略,使得SAPF在正序与负序电压下都能够正常抑制谐波,最后通过实验验证了理论分析的正确性。展开更多
We present an ameliorated arctangent algorithm based on phase-locked loop for digital Doppler signal processing,utilized within the heterodyne detection system. We define the error gain factor given by the approximati...We present an ameliorated arctangent algorithm based on phase-locked loop for digital Doppler signal processing,utilized within the heterodyne detection system. We define the error gain factor given by the approximation of Taylor expansion by means of a comparison of the measured values and true values. Exact expressions are derived for the amplitude error of two in-phase & quadrature signals and the frequency error of the acousto-optic modulator. Numerical simulation results and experimental results make it clear that the dynamic instability of the intermediate frequency signals leads to cumulative errors, which will spiral upward. An improved arctangent algorithm for the heterodyne detection is proposed to eliminate the cumulative errors and harmonic components. Depending on the narrow-band filter, our experiments were performed to realize the detectable displacement of 20 nm at a detection distance of 20 m. The aim of this paper is the demonstration of the optimized arctangent algorithm as a powerful approach to the demodulation algorithm, which will advance the signal-to-noise ratio and measurement accuracy of the heterodyne detection system.展开更多
Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, the...Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, there are some problems in the conventional method, such as the error of amplitude, the shift of phase angle and the non-determinacy of initial oriented angle. In this paper, two one-order low-pass filters are adopted instead of the pure integrator in the virtual line-flux-linkage observer, which can steady the phase and amplitude. Furthermore, an original scheme of harmonics detection under the rotating coordinate is advanced based on the simplified space vector pulse width modulation (SVPWM) strategy. Meanwhile, by using the new SVPWM algorithm, the voltage space vector diagram of the three-level inverter can be simplified and applied into that of two-level inverter, and this makes the control for Neutral Point potential easier.展开更多
文摘当并联有源电力滤波器(Shunt Active Power Filter,SAPF)接入电网时相序错接,将导致锁相环无法正确锁相,不能正常进行谐波抑制与无功补偿。为了解决这一问题,文章分析了网侧电压相序对SAPF的影响,推导出同步旋转坐标系下的电压d轴与q轴分量,提出了利用同步旋转坐标变换与滑窗平均滤波器由软件实现的相序检测方法。同时针对相序检测方案的性能进行了研究,得出滑窗滤波器窗口长度与相序判断阈值间的关系及判断SAPF网侧电压相序的判断原理。在获得了电网相序的基础上,设计了三相SAPF错序校正策略,使得SAPF在正序与负序电压下都能够正常抑制谐波,最后通过实验验证了理论分析的正确性。
基金supported by Key Research Program of Frontier Science,Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH014)the Yong Scientists Fund of the National Natural Science Foundation of China(Grant No.61205143)
文摘We present an ameliorated arctangent algorithm based on phase-locked loop for digital Doppler signal processing,utilized within the heterodyne detection system. We define the error gain factor given by the approximation of Taylor expansion by means of a comparison of the measured values and true values. Exact expressions are derived for the amplitude error of two in-phase & quadrature signals and the frequency error of the acousto-optic modulator. Numerical simulation results and experimental results make it clear that the dynamic instability of the intermediate frequency signals leads to cumulative errors, which will spiral upward. An improved arctangent algorithm for the heterodyne detection is proposed to eliminate the cumulative errors and harmonic components. Depending on the narrow-band filter, our experiments were performed to realize the detectable displacement of 20 nm at a detection distance of 20 m. The aim of this paper is the demonstration of the optimized arctangent algorithm as a powerful approach to the demodulation algorithm, which will advance the signal-to-noise ratio and measurement accuracy of the heterodyne detection system.
文摘Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, there are some problems in the conventional method, such as the error of amplitude, the shift of phase angle and the non-determinacy of initial oriented angle. In this paper, two one-order low-pass filters are adopted instead of the pure integrator in the virtual line-flux-linkage observer, which can steady the phase and amplitude. Furthermore, an original scheme of harmonics detection under the rotating coordinate is advanced based on the simplified space vector pulse width modulation (SVPWM) strategy. Meanwhile, by using the new SVPWM algorithm, the voltage space vector diagram of the three-level inverter can be simplified and applied into that of two-level inverter, and this makes the control for Neutral Point potential easier.
