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 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.

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.

scholarly journals Evaluation of Moving Average Window Technique as Low-pass Filter in Microprocessor-Based Protecting Relays

2017 ◽  
Vol 7 (6) ◽  
pp. 2177-2183
Author(s):  
N. Khodabakhshi-Javinani ◽  
H. Askarian Abyaneh
Keyword(s):  
Moving Average ◽  
Least Square ◽  
Main Process ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Dc Offset ◽  
Signal Flow Graphs ◽  
Window Technique ◽  
Low Pass ◽  
Flow Graphs

Over the last decades, with the increase in the use of harmonic source devices, the filtering process has received more attention than ever before. Digital relays operate according to accurate thresholds and precise setting values. In signal flow graphs of relays, the low-pass filter plays a crucial role in pre-filtering and purifying waveforms performance estimating techniques to estimate the expected impedances, currents, voltage etc. The main process is conducted in the CPU through methods such as Man and Morrison, Fourier, Walsh-based techniques, least-square methods etc. To purify waveforms polluted with low-order harmonics, it is necessary to design and embed cutting frequency in a narrow band which would be costly. In this article, a technique is presented which is able to eliminate specified harmonics, noise and DC offset, attenuate whole harmonic order and hand low-pass filtered signals to CPU. The proposed method is evaluated by eight case studies and compared with first and second order low-pass filter.

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.

scholarly journals Higher-Order Sliding Mode Observer for Speed and Position Estimation in PMSM

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Suneel K. Kommuri ◽  
Kalyana C. Veluvolu ◽  
M. Defoort ◽  
Yeng C. Soh
Keyword(s):  
Sliding Mode ◽  
Permanent Magnet Synchronous Motor ◽  
Estimation Method ◽  
Higher Order ◽  
Position Estimation ◽  
Accurate Estimation ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Three Phase ◽  
Low Pass

This paper presents a speed and position estimation method for the permanent magnet synchronous motor (PMSM) based on higher-order sliding mode (HOSM) observer. The back electromotive forces (EMFs) in the PMSM are treated as unknown inputs and are estimated with the HOSM observer without the need of low-pass filter and phase compensation modules. With the estimation of back EMFs, an accurate estimation of speed and rotor position can be obtained. Further, the proposed method completely eliminates chattering. Experimental results with a 26 W three-phase PMSM demonstrate the effectiveness of the proposed method.

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 A Unified Method for Online Detection of Phase Variables and Symmetrical Components of Unbalanced Three-Phase Systems with Harmonic Distortion

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3243 ◽  
Author(s):  
Christoph M. Hackl ◽  
Markus Landerer
Keyword(s):  
Frequency Estimation ◽  
Harmonic Distortion ◽  
System Stability ◽  
Online Detection ◽  
Sequence Detection ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Symmetrical Components ◽  
Three Phase ◽  
Low Pass

This paper presents a method for online detection of symmetrical components of arbitrarily distorted and biased three-phase input signals. This method is based on Second-Order Generalized Integrators (SOGIs), for which a new tuning based on a gradient search is presented to achieve the fastest possible estimation. Frequency estimation is achieved by a Frequency Locked Loop (FLL) with Gain Normalization (GN) for which an Output Saturation (OS) is applied; this OS guarantees stability of the overall system. Offset detection is implemented by a combination of High-Pass Filter (HPF) and HPF-Amplitude Phase Correction (APC); the HPF filters out any offset, where the APC reconstructs the original offset-free signal. An identical method (APC) can be used for the implemented Low-Pass Filter (LPF) used for noise filtering. The resulting estimates are then used for Harmonic Sequence Detection (HSD) of each harmonic. For the overall system, stability is proven. The estimation performances of the proposed overall system are verified by simulation results. The improvements in tuning and offset detection are compared to standard approaches.

scholarly journals Tan-Sun Transformation-Based Phase-Locked Loop in Detection of the Grid Synchronous Signals under Distorted Grid Conditions

Electronics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 674
Author(s):  
Guangjun Tan ◽  
Chunan Zong ◽  
Xiaofeng Sun
Keyword(s):  
Response Speed ◽  
Phase Locked Loop ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Estimated Parameters ◽  
Distorted Grid ◽  
Three Phase ◽  
Low Pass ◽  
Clarke Transformation ◽  
System Order

When three-phase voltages are polluted with unbalance, DC offsets, or higher harmonics, it is a challenge to quickly detect their parameters such as phases, frequency, and amplitudes. This paper proposes a phase-locked loop (PLL) for the three-phase non-ideal voltages based on the decoupling network composed of two submodules. One submodule is used to detect the parameters of the fundamental and direct-current voltages based on Tan-Sun transformation, and the other is used to detect the parameters of the higher-harmonic voltages based on Clarke transformation. By selecting the proper decoupling vector by mapping Hilbert space to Euclidean space, the decoupling control for each estimated parameter can be realized. The settling time of the control law can be set the same for each estimated parameter to further improve the response speed of the whole PLL system. The system order equals the number of the estimated parameters in each submodule except that a low-pass filter is required to estimate the average amplitude of the fundamental voltages, so the whole PLL structure is very simple. The simulation and experimental results are provided in the end to validate the effectiveness of the proposed PLL technique in terms of the steady and transient performance.

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