Praveen Tripathy

A robust TLS-ESPIRIT method using covariance approach for identification of low-frequency oscillatory mode in power systems

A robust spectral estimation technique for identifying low frequency oscillatory mode is presented in this paper. The effect of outliers is taken into account in the proposed method which occurs due to temporary fault in network or measuring instruments. In order to reduce the effect of such bad data the paper presents a robust covariance approach based TLS-ESPIRIT estimation using multivariate M (MM) estimator. Comparison of the modified TLS-ESPIRIT method with the proposed method are done on two test signals for mode identification at different signal-to-noise ratio (SNR). Efficiency of the proposed method is obtained in presence of outliers through Monte Carlo simulations. Comparison of the proposed method with the TLS-ESPIRIT method is also carried out on real time measurement data of Western Electricity Coordinating Council (WECC) network.

A nonlinear filtering technique along with RD and TLS-ESPRIT for mode identification of ambient data

The analysis of electromechanical modes has become a major concern in power system. A spectral estimation technique using a nonlinear filter for identifying the inter-area oscillatory modes for ambient data is presented in this paper. The proposed method contains three steps: (1) non-linear filtering to remove the non-linear trends from the ambient signals (2) Random decrement (RD) technique for obtaining the free decay response from the pre-filtered ambient data and (3) TLS-ESPRIT method for estimating the frequency and damping from these impulse responses obtained using RD. The proposed method is compared with RDT-TLS-ESPRIT method using simulated test signals for ambient data. Comparison of the proposed method is further carried out for actual ambient signals received from a PMU connected to Indian grid. The results shows that the proposed method is able to identify the modes accurately, and hence is suitable for application in wide area monitoring of oscillatory modes.

Development of Phasor Estimation Algorithm for P-Class PMU Suitable in Protection Applications

This paper proposes a phasor estimation algorithm for P-class phasor measurement unit suitable in protection applications using Hilbert transform and convolution of a signal. As the protective relay requires extracted fundamental component of the phasor for its operation, the author’s introduced an algorithm to estimate a robust phasor corresponding to the fundamental component which is close to the actual signal in

Modeling and optimal design of small HAWT blades for analyzing the starting torque behavior

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A Robust Fault Detection and Discrimination Technique for Transmission Lines

-norm. Though IEEE C37.118.1a-2014 standard does not specify the accuracy requirements of phasor under transient condition, the performance of phasor estimator is tested under different dynamic conditions as per IEEE C37.118.1a-2014 standard. The effectiveness of proposed algorithm has also been verified on modified two area power system during fault along with the data generated by the experimental setup in laboratory. The results revealed that the proposed algorithm estimates the phasor accurately irrespective of distortion present in the sinusoidal signals. Furthermore, the proposed estimator inherently filters harmonics, immune to decaying dc components, detects sharp changes in a signal during faults, and effectively works under complex modulated conditions. The above scenario appears frequently in a power system with distributed energy sources. The simplicity, robustness, and generality of the proposed algorithm suits for wide area measurement systems to measure the voltage and current phasors during disturbance in the smart power system networks.

An efficient wavelet based technique for oscillatory mode identification of ambient data via RD and TLS-ESPRIT

This paper presents a computational framework for an optimal aerodynamic blade design. Analysis of the wind turbine rotor is conducted using blade element momentum (BEM) theory. The geometric parameters of the wind turbine also have been calculated by BEM theory. The methodology and design approach is discussed in detail throughout this paper. A small three-bladed horizontal axis wind turbine (HAWT) is designed to improve its starting torque behaviour. The study of the starting torque behaviour, its analysis, and a new approach to smoothen it, is the important part of this work. The simulation results show that a turbine starts rotating with a smooth rising torque, and after ten seconds it gains a constant torque and a constant angular velocity which seems to be quite encouraging thus reducing the mechanical vibration of the system. The MATLAB is used to get the blade geometry parameters and aerodynamic forces along the blade span, the Pro/ENGINEER is used for the solid structure modeling of the wind turbine and ADAMS is being used for the simulation purpose.

Estimation of phasor under dynamic conditions using convolution

The complex and large power systems of modern time with distributed generation are more prone to the faults. Conventionally, the zone based primary and backup protection relies mainly on the information of positive sequence impedance sensed by the relay to protect these lines. The phenomena such as power swings, load encroachment, etc., can also result into low impedance and can trigger the cascade tripping of relays. In this paper, we proposed a robust fault detection and discrimination (RFDD) technique for transmission lines, which utilizes a robust method of phasor estimation to compute accurate fault impedance along with a feature value extracted from the samples of voltage and current signals. The effectiveness of the proposed RFDD technique has been tested and validated on IEEE 14-bus system, six generator 23-bus system and reduced NEREB 29-bus Indian power system with distributed generation using Siemens PSS/Sincal software. The results from simulation explore that RFDD technique can enhance the capability of distance protection relays for the future electric grids.

State estimation of DFIG using an Extended Kalman Filter with an augmented state model

This paper proposes a spectral estimation technique for identification of inter-area oscillatory modes using ambient data. In order to mitigate the effect of high noise level, the proposed method has used a combination of wavelet, random decrement (RD) and modified TLS-ESPRIT for mode identification. The main contribution of this paper is to find the optimal set of wavelet coefficients to represent the clean signal for mode estimation. The proposed method is compared with non-linear filtering and random decrement technique-Ibrahim time domain (RDT-ITD) method over the synthetic signals resembling ambient signals. The effectiveness of the proposed method is further validated for real time ambient data obtained from a PMU located in North Eastern Regional Electricity Board (NEREB) of India and on the probing data of the Western Electricity Coordinating Council (WECC).

Application of bridge-type FCL for betterment of FRT capability for DFIG-based wind turbine

The paper introduces a simple, fast and computationally efficient phasor estimation algorithm under dynamic conditions using convolution analysis. The performance of convolution based phasor estimator is effectively tested under different dynamic/noisy conditions as per IEEE C37.118.1-2011 standards. The results revealed that the proposed algorithm estimates the dynamic phasor accurately irrespective of distortion present in the sinusoidal signals. The proposed algorithm enhances the phasor estimation process to be more general and independent of phasor models of a signal. Furthermore, the proposed estimator inherently filters noise and harmonics, immune to decaying dc components, detects sharp changes in a signal during faults and effectively works under complex modulated conditions. The simplicity, robustness and generality of the proposed algorithm best suits for wide area measurement systems to measure the voltage and current phasors during disturbance in the power system networks.

Development of Dictionary-Based Phasor Estimator Suitable for P-Class Phasor Measurement Unit

This paper presents a novel method for state estimation in doubly fed induction generators (DFIGs) using an Extended Kalman Filter. In this work, the conventional nonlinear state space model of a DFIG has been augmented with additional states in order to make rotor position and speed estimates more robust to disturbances. The effectiveness of this method has been tested for various transient cases using MATLAB/Simulink.