Total Least Square Estimation Of Signal Parameters Via Rotational Invariance Techniques Research Articles

Additional Damping Control of a Hybrid Multi-infeed DC System with a Wind Farm

Background: In a hybrid multi-infeed direct current (HMIDC) system, the interaction between the AC and DC systems will have an influence on the damping characteristics of the system, while a doubly-fed induction generator (DFIG) -based wind turbine connected to the grid complicates the coupling between AC and DC. Objective: Based on the basic principles of wind power generation and low-frequency oscillation (LFO), a DFIG -based wind turbine is respectively connected to the LCC-HVDC side and VSC-HVSC side of an HMIDC system to study the influence of the oscillation mode on a hybrid system with different wind power access locations, and two kinds of additional DC damping controllers are designed to suppress the LFO. Comparing the effects of different additional DC damping controllers on the suppression of the LFO in the system. Methods: First, the total least squares- estimation of signal parameters via rotational invariance techniques (TLS-ESPRIT) is used to obtain the system’s oscillation mode. Second, the transfer function is determined by the Butterworth bandpass filter. Third, the LCC-HVDC and VSC-HVDC additional damping controllers are designed based on the H2/H∞ hybrid control theory. Results: The designed additional DC damping controller has a good suppression effect on LFO in the HMIDC system and can meet the system damping deficit. The effect of the LCC-HVDC additional damping controller is better than that of VSC-HVDC. Conclusion: Through a simulation analysis on PSCAD/EMTDC simulation software, the effectiveness of the designed additional DC damping controller is verified.

An Adaptive TLS-ESPRIT Algorithm Based on an S-G Filter for Analysis of Low Frequency Oscillation in Wide Area Measurement Systems

In this paper, a two-stage mode identification algorithm including preprocessing and identification steps is introduced to solve the problems of measuring noise and inaccurate mode identification in the analysis of low-frequency oscillation (LFO) in a wide area measurement systems (WAMSs). S-G filter de-noising is utilized for the preprocessing. An adaptive total least squares-estimation of signal parameters via rotational invariance techniques (TLS-ESPRIT) algorithm with the order setting of the singular value accumulation percentage adjacency increment ratio (SVAPAIR) is utilized for the identifying stage. The S-G filter is used to mitigate the measuring of LFO noise of the system. Furthermore, the SVAPAIR is adopted to achieve an adaptive and precise determination of the LFO order, and then LFO parameters are extracted by the adaptive TLS-ESPRIT algorithm. The proposed algorithm has been tested and verified using the IEEE four-generator two-area system and the actual measured data of the LFO accident in the North American power grid. The simulation and experimental result showed that the proposed algorithm has better adaptability, anti-noise characteristic, and robustness compared to those of the conventional Prony, matrix pencil (MP), and TLS-ESPRIT algorithms.

Identification of Combined Power Quality Disturbances Using Singular Value Decomposition (SVD) and Total Least Squares-Estimation of Signal Parameters via Rotational Invariance Techniques (TLS-ESPRIT)

In order to identify various kinds of combined power quality disturbances, the singular value decomposition (SVD) and the improved total least squares-estimation of signal parameters via rotational invariance techniques (TLS-ESPRIT) are combined as the basis of disturbance identification in this paper. SVD is applied to identify the catastrophe points of disturbance intervals, based on which the disturbance intervals are segmented. Then the improved TLS-ESPRIT optimized by singular value norm method is used to analyze each data segment, and extract the amplitude, frequency, attenuation coefficient and initial phase of various kinds of disturbances. Multi-group combined disturbance test signals are constructed by MATLAB and the proposed method is also tested by the measured data of IEEE Power and Energy Society (PES) Database. The test results show that the new method proposed has a relatively higher accuracy than conventional TLS-ESPRIT, which could be used in the identification of measured data.

Robust design method for power oscillation damping controller of STATCOM based on residue and TLS-ESPRIT

SUMMARY Due to the diversity of operating conditions of real-time power system, traditional power oscillation damping controller (PODC) of static synchronous compensator (STATCOM), which only considers single operating condition, could not provide sufficient damping when operating condition changes. To solve this problem, this paper proposes a robust design method for PODC. The total least squares-estimation of signal parameters via rotational invariance techniques (TLS-ESPRIT), which performs well in term of anti-noise and accuracy, is suggested to identify the transfer function and residues of the system. The residue-based approach considers several typical operating conditions so that the designed PODC could adapt to multiple operating conditions. The simulation result demonstrates that, compared with the traditional method, PODC of STATCOM designed by the proposed method damps the low-frequency oscillation more effectively and is more adaptable to the change of operating conditions. Copyright © 2013 John Wiley & Sons, Ltd.

High-Accuracy Fundamental Frequency Detection in Power System

A novel method on frequency measurement based on improved TLS-ESPRIT (total least square estimation of signal parameters via rotational invariance techniques) is proposed in this paper with the research on fundamental frequency measurement in power system. TLS-ESPRIT is belong to subspace estimation in modern signal process. Noise is included in signal model, so it is independent on noise. But the same multi-poles cannot be taken when signal is in noise and based on TLS-ESPRIT. Multiple poles restoring is presented to take the true poles accurately. It is revealed that fundamental frequency is detected accurately in harmonics, interharmonics, noise and frequency fluctuations and better anti-noise ability in particular better adaptiveness on time varying signal in amplitude by simulation results.

A Modified TLS-ESPRIT-Based Method for Low-Frequency Mode Identification in Power Systems Utilizing Synchrophasor Measurements

This paper proposes a method for online identification of modes corresponding to low-frequency oscillations in a power system. The proposed method has considered the effect of colored Gaussian noise produced due to filters used for signal preprocessing. In order to mitigate the effect of colored Gaussian noise, the paper first proposes a modified total least square estimation of signal parameters via rotational invariance techniques (TLS-ESPRIT) that utilizes first and second rotational shift invariance properties of the signal. In the next step, the modified TLS-ESPRIT utilizes the signal transformed in an orthogonal basis. The proposed method has been compared with the improved Prony, the TLS-ESPRIT and the fourth-order cumulant-based TLS-ESPRIT (4CB-TLS-ESPRIT) using a test signal for identification of the modes at different noise levels. Robustness of the proposed method is established in the presence of colored Gaussian noise through Monte Carlo simulations. Estimation of modes for a two-area power system, using the proposed method, is carried out in the present work. Comparison of the proposed method with other methods is also performed on real-time probing test data obtained from the Western Electricity Coordinating Council (WECC) network.

Islanding detection of grid connected distributed generators using TLS-ESPRIT

A critical protection requirement for grid connected distributed generators (DG) is anti-islanding protection. In this paper, a new islanding detection method is proposed based on monitoring the generator's frequency. Two new features, the frequency of oscillation and the damping factor of the generator's frequency output waveform, are extracted using the total least square-estimation of signal parameters via rotational invariance techniques (TLS-ESPRIT) algorithm. The proposed method has been tested under various scenarios such as load change, short circuit, and capacitor switching.

Dual-polarized array for signal-processing applications in wireless communications

A novel dual-polarized antenna array designed for a spatial division multiple access (SDMA) system working in the 1850-1990-MHz band is designed and built. The antenna is designed to have similar element patterns, and measurements of S-parameters and radiation patterns are presented. The array signal processing performance of the array using all elements and with no compensation for mutual coupling or differences in element patterns is studied through direction-of-arrival (DOA) estimation using total least squares estimation of signal parameters via rotational invariance techniques (TLS-ESPRIT). The results show that the accuracy of the DOA estimates is quite acceptable for wireless communication applications.