scholarly journals Study of Harmonic Detection Methods under Non-Ideal Conditions in Ship Power Network

2015 ◽  
Vol 22 (3) ◽  
pp. 82-89
Author(s):  
Xiao-Yan Xu ◽  
Janusz Mindykowski ◽  
Tomasz Tarasiuk ◽  
Chen Cheng
Keyword(s):  
Phase Lock Loop ◽  
Mean Value ◽  
Detection Methods ◽  
Harmonic Detection ◽  
Phase Voltage ◽  
Rapid Variation ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Three Phase ◽  
In Series

Abstract An improved harmonic detection method based on average arithmetic is proposed. According to the research results, the designed solution uses an LPF (low-pass-filter) and a mean value module connected in series instead of the conventional mean value module, and simultaneously, a three-phase voltage phase-locked module instead of commonly used PLL (phase lock loop) module is applied in order to reduce the influence caused by three-phase distorted voltage and rapid variation of load. The experimental results show that the application of this solution leads to increase in the accuracy of harmonics detection for distorted three-phase voltage and rapid variation of load.

scholarly journals A rapid harmonic detection method for grid-connected photovoltaic when three-phase voltage is unbalanced

2021 ◽  
Author(s):  
Tiezhou Wu ◽  
An Wang ◽  
Yawen Xu
Keyword(s):  
Phase Angle ◽  
Detection Method ◽  
Positive Sequence ◽  
Harmonic Detection ◽  
Phase Voltage ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Negative Sequence ◽  
Three Phase ◽  
Low Pass

Abstract By using power electronic devices, photovoltaic grid-connected power generation may inject harmonics into the power system. As the photovoltaic grid-connected inverter has the same basic structure as the active power filter, so the unified control of the photovoltaic grid and active filtering can be achieved. When the current unified control system compensates harmonics of the grid side, it mainly uses ip-iq harmonic detection method, which is based on instantaneous reactive power theory. When the three-phase voltage is unbalanced, the method has a large voltage phase angle detection error and the signal of the low-pass filter tracking system is long, detection time delay and even failure occur. This paper proposes an improved fast harmonic detection method. When phase deviation or amplitude change occurs to the three-phase voltage, the positive and negative-sequence voltages are simultaneously park transformed. The negative-sequence component is filtered by the current average module to obtain the fundamental amount of the voltage, then the phase angle of the positive-sequence voltage is accurately calculated to improve the harmonic current detection accuracy. Through the study of the integral method, it is found that the least common multiple of each harmonic period can be used as the integral interval, and the integral value is also zero, so the detection delay time is reduced by replacing the low-pass filter with an integration module. The simulation results show that the proposed harmonic detection algorithm can accurately detect harmonics when the three-phase voltage is unbalanced, and about 0.057 s improve the harmonic detection speed compared with the commonly used ip-iq method.

scholarly journals Improved harmonic detection method based on ip-iq theory

2021 ◽  
Vol 261 ◽  
pp. 01028
Author(s):  
Zhisen Yao ◽  
Guige Gao
Keyword(s):  
Detection Method ◽  
Phase Error ◽  
Response Speed ◽  
Detection Accuracy ◽  
Harmonic Detection ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
In Series ◽  
Filtering Effect

Based on the traditional ip-iq harmonic detection theory, the accuracy of harmonic detection is easily affected by the phase-locked loop (PLL) output phase error, and the single low-pass filter (LPF) detection accuracy and filtering effect cannot be simultaneously. In this paper, an improved harmonic detection method based on the second-order generalized integrator-frequency locked loop (SOGI-FLL) technique is proposed to generate sine and cosine signals with the same frequency as the grid voltage; The traditional low-pass filter and average filter are used in series to improve the response speed and accuracy. Through theoretical analysis of the improved harmonic detection method and simulation in MATLAB environment, the theory and simulation results prove the effectiveness of the improved method.

scholarly journals Improvement of DSOGI PLL Synchronization Algorithm with Filter on Three-Phase Grid-connected Photovoltaic System

2018 ◽  
Vol 18 (1) ◽  
pp. 35 ◽  
Author(s):  
Rofiatul Izah ◽  
Subiyanto Subiyanto ◽  
Dhidik Prastiyanto
Keyword(s):  
Reference Frame ◽  
Frequency Estimation ◽  
Photovoltaic System ◽  
Positive Sequence ◽  
Pv System ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Synchronous Reference Frame ◽  
Three Phase ◽  
Low Pass

Synchronous Reference Frame Phase Locked Loop (SRF PLL) has been widely used for synchronization three-phase grid-connected photovoltaic (PV) system. On the grid fault, SRF PLL distorted by negative sequence component and grid harmonic that caused an error in estimating parameter because of ripple and oscillation. This work combined SRF PLL with Dual Second Order Generalized Integrator (DSOGI) and filter to minimize ripple and minimize oscillation in the phase estimation and frequency estimation. DSOGI was used for filtering and obtaining the 90o shifted versions from the vαβ signals. These signals (vαβ) were generated from three phase grid voltage signal using Clarke transform. The vαβ signal was the inputs to the positive-sequence calculator (PSC). The positive-sequence vαβ was transformed to the dq synchronous reference frame and became an input to SRF-PLL to create the estimation frequency. This estimation frequency from SRF PLL was filtered by the low-pass filter to decrease grid harmonic. Moreover, the output of low-pass filter was a frequency adaptive. The performance of DSOGI PLL with filter is compared with DSOGI PLL, SRF PLL, and IEEE standard 1547(TM)-2003. The improvement of DSOGI PLL with filter gave better performances than DSOGI PLL and SRF PLLbecause it minimized ripples and oscillations in the phase and frequency estimations.

Adaptive Low-Pass Filter Based DC Offset Removal Technique for Three-Phase PLLs

2018 ◽  
Vol 65 (11) ◽  
pp. 9025-9029 ◽  
Author(s):  
Parag Kanjiya ◽  
Vinod Khadkikar ◽  
Mohamed Shawky El Moursi
Keyword(s):  
Pass Filter ◽  
Low Pass Filter ◽  
Dc Offset ◽  
Three Phase ◽  
Low Pass ◽  
Removal Technique

scholarly journals Detection of Computer Graphics Using Attention-Based Dual-Branch Convolutional Neural Network from Fused Color Components

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4743
Author(s):  
Peisong He ◽  
Haoliang Li ◽  
Hongxia Wang ◽  
Ruimei Zhang
Keyword(s):  
Neural Network ◽  
Computer Graphics ◽  
Convolutional Neural Network ◽  
Video Game ◽  
Detection Methods ◽  
Post Processing ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Generalized Patterns ◽  
Color Components

With the development of 3D rendering techniques, people can create photorealistic computer graphics (CG) easily with the advanced software, which is of great benefit to the video game and film industries. On the other hand, the abuse of CGs has threatened the integrity and authenticity of digital images. In the last decade, several detection methods of CGs have been proposed successfully. However, existing methods cannot provide reliable detection results for CGs with the small patch size and post-processing operations. To overcome the above-mentioned limitation, we proposed an attention-based dual-branch convolutional neural network (AD-CNN) to extract robust representations from fused color components. In pre-processing, raw RGB components and their blurred version with Gaussian low-pass filter are stacked together in channel-wise as the input for the AD-CNN, which aims to help the network learn more generalized patterns. The proposed AD-CNN starts with a dual-branch structure where two branches work in parallel and have the identical shallow CNN architecture, except that the first convolutional layer in each branch has various kernel sizes to exploit low-level forensics traces in multi-scale. The output features from each branch are jointly optimized by the attention-based fusion module which can assign the asymmetric weights to different branches automatically. Finally, the fused feature is fed into the following fully-connected layers to obtain final detection results. Comparative and self-analysis experiments have demonstrated the better detection capability and robustness of the proposed detection compared with other state-of-the-art methods under various experimental settings, especially for image patch with the small size and post-processing operations.

scholarly journals Low-Cost Position Sensorless Speed Control of PMSM Drive Using Four-Switch Inverter

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 741 ◽  
Author(s):  
Omer Kivanc ◽  
Salih Ozturk
Keyword(s):  
Control Method ◽  
Low Cost ◽  
Experimental Studies ◽  
Speed Control ◽  
Estimation Algorithm ◽  
Phase Lock Loop ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Current Controller ◽  
Position Sensorless

A low-cost position sensorless speed control method for permanent magnet synchronous motors (PMSMs) is proposed using a space vector PWM based four-switch three-phase (FSTP) inverter. The stator feedforward d q -axes voltages are obtained for the position sensorless PMSM drive. The q-axis current controller output with a first order low-pass filter formulates the rotor speed estimation algorithm in a closed-loop fashion similar to PLL (Phase Lock Loop) and the output of the d-axis current controller acts as the derivative representation in the stator feedforward voltage equation. The proposed method is quite insensitive to multiple simultaneous parameter variations such as rotor flux linkage and stator resistance due to the dynamic effects of the PI current regulator outputs that are used in the stator feedforward voltages with a proper value of K gain in the q-axis stator voltage equation. The feasibility and effectiveness of the proposed position sensorless speed control scheme for the PMSM drive using an FSTP inverter are verified by simulation and experimental studies.

Comparison and Analysis on Two Improved Detecting Methods for Harmonics without PLL in Single-Phase Circuit

2011 ◽  
Vol 130-134 ◽  
pp. 3928-3932
Author(s):  
Ju Xia Ding ◽  
Xiu Feng Zhang ◽  
Hua Jun Zhang
Keyword(s):  
Single Phase ◽  
Continuous Process ◽  
Response Speed ◽  
Theoretical Method ◽  
Phase Lock Loop ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Average Theory ◽  
Detecting Method

In order to reduce the error of the phase lock-loop (PLL) and compensate the delay of the low pass filter on harmonics detection, In the paper, a detecting-method without PLL in single-phase circuit is researched. In this method, the PLL and LPF are omitted, the feedback and average theory are used, so that the problem of detecting accuracy induced by PLL and real-time induced by LPF is solved. It is testified through comparison, analysis and simulation, that both methods can reduce the latency, improve dynamic response speed, the feedback method can reduce the delay in a dynamic, continuous process, while the average theoretical method can reduce the delay quantitatively.

The Analysis and Design of Three-Phase Static Inverter Deadband Effect and Harmonic Suppression

2013 ◽  
Vol 575-576 ◽  
pp. 293-296
Author(s):  
Qun Min Yan
Keyword(s):  
Control Method ◽  
Design Method ◽  
Harmonic Suppression ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Analysis And Design ◽  
Three Phase ◽  
Low Pass ◽  
Harmonic Components ◽  
Simulated Analysis

in order to solve the problem of three-phase static inverter output waveform distortion, detailed analyzed of the voltage distortion caused by the deadband effect and the resulting harmonic components. The control method is proposed to set the deadband time combining with the voltage compensation, while in order to improve the inverter output, the converter output to design a trap filter and a low pass filter cascaded filtering circuit. Simulated analysis the entire system though Saber, using the digital chip TMS320F2812 to achieve appropriate compensation strategies, simulation results and experimental results have all proved the effectiveness of the design method.

Real-Time Tsunami Data Assimilation of S-Net Pressure Gauge Records during the 2016 Fukushima Earthquake

2021 ◽  
Author(s):  
Yuchen Wang ◽  
Kenji Satake
Keyword(s):  
Data Assimilation ◽  
Real Time ◽  
Pressure Gauge ◽  
Detection Algorithm ◽  
Detection Methods ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Tsunami Detection ◽  
Seafloor Observation ◽  
Net Pressure

Abstract The 2016 Fukushima earthquake (M 7.4) generated a moderate tsunami, which was recorded by the offshore pressure gauges of the Seafloor Observation Network for Earthquakes and Tsunamis (S-net). We used 28 S-net pressure gauge records for tsunami data assimilation and forecasted the tsunami waveforms at four tide gauges on the Sanriku coast. The S-net raw records were processed using two different methods. In the first method, we removed the tidal components by polynomial fitting and applied a low-pass filter. In the second method, we used a real-time tsunami detection algorithm based on ensemble empirical mode decomposition to extract the tsunami signals, imitating real-time operations for tsunami early warning. The forecast accuracy scores of the two detection methods are 60% and 74%, respectively, for a time window of 35 min, but they improve to 89% and 94% if we neglect the stations with imperfect modeling or insufficient offshore observations. Hence, the tsunami data assimilation approach can be put into practice with the help of the real-time tsunami detection algorithm.

DC-Bus Voltage Control Strategy Based on Low-Pass Filter for Three-Phase Four-Wire APF

2013 ◽  
Vol 732-733 ◽  
pp. 1167-1170
Author(s):  
Xia Feng ◽  
Xiao Jian Zhong ◽  
Qun Wei Xu ◽  
Guo Zhu Chen
Keyword(s):  
Voltage Control ◽  
Stable Operation ◽  
Voltage Control Strategy ◽  
Signal Model ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Three Phase ◽  
Low Pass ◽  
Dc Bus ◽  
Bus Voltage

The DC-bus voltage control is critical for stable operation of the three-phase four-wire Active Power Filter. DC-bus stable voltage loop and balance voltage loop are established based on the small signal model. Considering the disadvantages of the traditional PI control, second-order low-pass filter is introduced into the proposed controller. Simulation and experimental results are conducted to validate the effectiveness of the proposed strategy.

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