scholarly journals Accurate Parameter Estimation for Unbalanced Three-Phase System

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Yuan Chen ◽  
Hing Cheung So
Keyword(s):  
Parameter Estimation ◽  
Frequency Estimation ◽  
Nonlinear Least Squares ◽  
Phase System ◽  
Mean Square ◽  
Least Mean Square ◽  
Error Performance ◽  
Control Console ◽  
Three Phase ◽  
And Control

Smart grid is an intelligent power generation and control console in modern electricity networks, where the unbalanced three-phase power system is the commonly used model. Here, parameter estimation for this system is addressed. After converting the three-phase waveforms into a pair of orthogonal signals via theαβ-transformation, the nonlinear least squares (NLS) estimator is developed for accurately finding the frequency, phase, and voltage parameters. The estimator is realized by the Newton-Raphson scheme, whose global convergence is studied in this paper. Computer simulations show that the mean square error performance of NLS method can attain the Cramér-Rao lower bound. Moreover, our proposal provides more accurate frequency estimation when compared with the complex least mean square (CLMS) and augmented CLMS.

scholarly journals Adaptive Filtering-Based Pseudo Open-Loop Three-Phase Grid-Synchronization Technique

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2927 ◽  
Author(s):  
Hafiz Ahmed ◽  
Samet Biricik ◽  
Elhoussin Elbouchikhi ◽  
Mohamed Benbouzid
Keyword(s):  
Adaptive Filtering ◽  
Adaptive Filters ◽  
Frequency Estimation ◽  
Open Loop ◽  
Phase System ◽  
Comparative Performance ◽  
Reduced Order ◽  
Grid Synchronization ◽  
Synchronization Problem ◽  
Three Phase

This paper studies the grid-synchronization problem of three-phase system. Second-order adaptive filters are a popular tool for grid-synchronization. In this context, reduced-order generalized integrator has attracted some attention in recent time. However, existing implementations cannot control directly the closed-loop poles (real and imaginary) of reduced-order generalized integrator. To overcome this limitation, this paper proposes a novel reduced-order generalized integrator structure. To make the proposed technique frequency adaptive, an open-loop frequency estimation technique is also used. Comparative performance analysis are provided over two other advanced and recently proposed techniques. Results demonstrate the suitability and effectiveness of the proposed technique.

A Three-phase to Seven-phase Energy Transformation under Unbalanced Supply Voltage

2018 ◽  
Author(s):  
Md Tabrez ◽  
Pradip Kumar Sadhu ◽  
Atif Iqbal ◽  
Farhad Ilahi Baksh
Keyword(s):  
Power Transmission ◽  
Supply Voltage ◽  
Power Input ◽  
Phase System ◽  
Ac Power ◽  
Three Phase ◽  
Sequence Components ◽  
Definition Of ◽  
And Control ◽  
Generation Power

In the recent past, multiphase power generation, power transmission, and electrical drive system are the main focus of research due to their several advantages over three phase. Multiphase drives have better performance over three-phase drives. A multiphase transformer is required at the input of a fixed frequency multiphase drive, rectifier circuit for HVDC applications and multiphase generation and transmission systems. This paper investigates a static three to seven phase conversion technique and presents a design of transformer and control strategy to analyze the effect of unbalanced supply on a three phase to seven phase transformer. The transformer so designed takes three phase as input and seven phase output is obtained at the secondary terminals. The paper also discusses input-output unbalancing. A complete design, analysis, simulation of the proposed technique and experimental validation is presented in this paper. Experimental and simulation results prove that the presented design produced a seven-phase from a tree-phase ac power. Input unbalance is reflected to output but is less than the input unbalance. A seven phase output is not produced if one phase of input is open and the transformer has more than three limbs for flux to flow. A balanced seven phase output in steady state is produced even in one phase open condition for a three limb core type transformer. A new definition of sequence components of an unbalanced seven phase system is defined in this paper.

scholarly journals Unified Power Flow Controller Based on Autotransformer Structure

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1542
Author(s):  
Hyun-Jun Lee ◽  
Dae-Shik Lee ◽  
Young-Doo Yoon
Keyword(s):  
Power Flow ◽  
Single Phase ◽  
Low Voltage ◽  
Power Converter ◽  
Unified Power Flow Controller ◽  
Phase System ◽  
Three Phase ◽  
Flow Controller ◽  
And Control ◽  
Power Flow Controller

This paper proposes a new unified power flow controller (UPFC) topology. A single phase of them system with the proposed topology consists of an N:2 transformer with a center tap at the low-voltage side and a power converter module comprising full- and half-bridge converters. A three-phase system can be implemented with three devices. While the conventional UPFC topology uses two three-phase transformers, which are called series and parallel transformers, the proposed topology utilizes three single-phase transformers to implement a three-phase UPFC system. By using an autotransformer structure, the power rating of the transformers and the voltage rating of switches in the power converter module can be significantly decreased. As a result, it is possible to reduce the installation spaces and costs compared with the conventional UPFC topology. In addition, by adopting a full- and half-bridge converter structure, the proposed topology can be easily implemented with conventional power devices and control techniques. The techniques used to control the proposed topology are described in this paper. The results obtained from simulations and experiments verify the effectiveness of the proposed UPFC topology.

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