Z.Q. Bo

Bio: Z.Q. Bo is an academic researcher from Alstom. The author has contributed to research in topics: Fault (power engineering) & Power-system protection. The author has an hindex of 4, co-authored 7 publications receiving 69 citations.

Application of wavelet transform in transient protection-case study: busbar protection

Abstract: This paper presents extensive studies of the application of wavelet transforms to detecting power system faults and describes a number of new protection principles and techniques based on the wavelet transform. These include a number of novel protection schemes for the protection of transmission lines, distribution feeders, generators and transformers. The significant advantages of these protection schemes are outlined in the paper. Finally the application of the proposed technique to busbar protection is presented to examine the feasibility of new protective algorithm.

New approach of fault detection and fault phase selection based on initial current traveling waves

Abstract: This paper presents a new principle of fault analyzing based on initial current traveling waves and a new algorithm of fault detection and fault phase selection based on the wavelet transforms. Through comparing the amplitudes of module maxima of wavelet transform in different scales, the fault can be detected. Through matching the characteristics of different fault types, the fault phase can be identified. This new approach of fault detection and fault phase selection, including the new principle and new algorithm, is specially designed for the ultra-high-speed protective relaying, which is based on the traveling waves. The use of the new approach provides an attractive potential solution to the long-standing problems of accurate and fast fault detection and fault phase selection. Extensive theoretical studies and simulations using EMTP have proved that the correctness and effectiveness of the proposed new approach.

Adaptive reclosure using high frequency fault transients

Abstract: A new signal processing algorithm for arcing faults detection based on the high frequency current transient is presented in this paper. In transient faults, arc current extinguishes and then ignites, and this periodically disturbs fault current. After several cycles, when transient signals by the fault decay a lot, the arc disturbance can be identified by the wavelet transform. The feasibility of this algorithm has been tested by computer simulation.

New principle of high-speed directional relay

Abstract: This paper presents a high-speed directional relay for the directional-comparison protection of EHV transmission lines using the power frequency fault components. The relay calculates the compensated voltage and the reference voltage firstly, then the direction of a fault will be determined by comparing the magnitudes of these two voltages. This relay possesses good performance, such as high sensitivity and fast action under various system and fault conditions. A 500 kV transmission system is modeled by EMTP. Simulation results show that the high-speed directional relay is sensible and reliable under different system configurations and fault conditions.

A new technique for power transformer protection using discrete dyadic wavelet transform

Abstract: As one of the most important elements in modern power system, the transformer is responsible for the successful power transmission and distribution. Any unscheduled repair work, especially replacement of a faulty transformer, is very expensive and time consuming. Starting from here, this paper discusses an approach to introduce a wavelet-based view to identify inrush and other transformer faults. Furthermore, by careful cataloging and comparing, the authors found distinct characteristics corresponding to fault and inrush, on the basis of which they proposed a generalized new criterion for inrush identification, that can help to enhance protection reliability. The outcome of numerical simulation shows the effectiveness of the algorithm.

Fault Detection and Classification in EHV Transmission Line Based on Wavelet Singular Entropy

Abstract: A novel technique for fault detection and classification in the extremely high-voltage transmission line using the fault transients is proposed in this paper. The novel technique, called wavelet singular entropy (WSE), incorporates the advantages of the wavelet transform, singular value decomposition, and Shannon entropy. WSE is capable of being immune to the noise in the fault transient and not being affected by the transient magnitude so it can be used to extract features automatically from fault transients and express the fault features intuitively and quantitatively even in the case of high-noise and low-magnitude fault transients. The WSE-based fault detection is performed in this paper, which proves the availability and superiority of WSE technique in fault detection. A novel algorithm based on WSE is put forward for fault classification and it is verified to be effective and reliable under various fault conditions, such as fault type, fault inception time, fault resistance, and fault location. Therefore, the proposed WSE-based fault detection and classification is feasible and has great potential in practical applications.

Approaches in High Impedance Fault Detection - A Chronological Review

Abstract: This paper reviews the major contributions to the high impedance fault (HIF) detection field throughout a 48-year period, from 1960 up to 2008, from classic approaches to heuristic alg ...

Design and evaluation of a directional algorithm for transmission-line protection based on positive- sequence fault components

Abstract: A directional relay algorithm for EHV transmission lines using positive-sequence fault components is presented. By comparing the phase relationship between the voltage and current measured at the relay point, the algorithm can determine correctly whether a fault is in the forward or backward direction. Specially designed techniques and logic are adopted to solve the difficult problems that exist in a real system. The signal-processing procedure for extracting the required fault components is provided in detail. Extensive simulation studies were conducted on a 500 kV system model using EMTDC. Theoretical analysis and simulation results show that the proposed algorithm provides adequate sensitivity, reliability and a fast operating response under a variety of system and fault conditions. In addition, it provides significant advantages over conventional directional relays, and these are discussed in the paper.

Critical aspects on wavelet transforms based fault identification procedures in HV transmission line

Abstract: The fault identification process in transmission systems involves three functions: discrimination, classification and phase selection. The current study classifies the methods that applied for each function. Moreover, this study introduces criticism and assessment study that helps the power system protection engineer to choose the best fault identification scheme at responsible indices. Investigated solutions for the drawbacks appeared with the previous methods are suggested. This study also proposes sensitive and automated fault identification scheme to solve the existing challenges such as high-impedance faults (HIFs), non-linear modelling of arcing etc. Several simulation studies are employed using alternative transients program/electromagnetic transient program (ATP/EMTP) package on a sample 500 kV test system to ensure the performances of the proposed scheme compared with the previous methods. Simulation results concluded that: the proposed identification scheme has the ability to discriminate correctly between HIF and low-impedance faults using current signal captured from one end only. Moreover, the proposed scheme alleviates perfectly the problems associated with load variations by adaptive threshold settings and reduces the impacts on the environmental and external phenomena.

High-speed differential busbar protection using wavelet-packet transform

Abstract: A novel wavelet-packet-transform- (WPT-) based differential busbar-protection technique is presented. The paper uses the wavelet-packet- transform (WPT) method to extract features from a fault-current signal. The WPT can decompose the fault signal into different frequency bands in the time domain. The differential signal is computed from the decomposed extracted signal. The WPT-based differential busbar-protection scheme solves several problems of current protective relays. The CT error and ratio-mismatch problems do not have any impact on the proposed WPT-based scheme. ATP simulations are used to test and validate the proposed technique for model-power-system faults.