F. Jiang

Bio: F. Jiang is an academic researcher. The author has contributed to research in topics: Wavelet transform & Power-system protection. The author has an hindex of 3, co-authored 3 publications receiving 49 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.

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.

Synchronization Strategy Based on Resonant Current Detection for Bidirectional Wireless Charging System

Abstract: Bidirectional wireless power transfer greatly improves the reliability of power supply. However, wireless communication between the primary and pickup controllers is usually required to transmit load information, which has time delay and is easily interfered by electromagnetic fields. Existing solutions to avoid the use of communication can be divided into three categories: additional dc/dc circuit, primary side bridge control, and secondary side bridge control. Compared with the other two methods, the secondary side bridge control has low loss and good robustness. But, it usually requires phase-locked loop (PLL) to eliminate the frequency error between primary and secondary side bridges, which increases the complexity. In this article, a constant current control strategy without communication is proposed. It is based on the secondary side bridge control and the switching sequence of the secondary side bridge is periodically synchronized according to the phase of the resonant current. It works robustly without the need for additional hardware such as PLL or Multiplier. The harmonic sensitivity analysis, parameter optimization design and stability analysis are carried out to improve the control efficiency. Experimental results based on a 1 kW prototype with dual LCC resonant network are presented to verify the effectiveness of the proposed control strategy.

Fault Identification of Winding Axial Displacement and Inter-turn Short Circuit for UHVDC Transformer

Abstract: Converter transformers are key primary equipment for UHVDC system. The nonlinear switching actions of thyristors seriously deteriorate the working conditions of station converters and make the probability of outage due to component aging remain high. In view of the deficiency of traditional fault diagnosis of converter transformers which mostly relies on non-electric quantity monitoring, this paper presents a method for fault identification of winding axial displacement and inter-turn short circuit based on transformer electrical waveforms by establishing a converter transformer lumped model and analyzing field recorded wave data. Firstly, the accuracy of the converter transformer’s simulation model is verified by comparing the simulation waveforms with the field recorded waveform data, which lays a foundation for obtaining usable fault data sets. Then, the fault features in converter transformer's electrical waveforms were extracted by elliptic equations, and the support vector machine (SVM) was constructed to judge the fault existence and identify the fault types. The test results show that the accuracy of the proposed method is higher than 70%. The effectiveness of transformer fault diagnosis using UHVDC field recording data is verified.

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.

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.

An overview of wavelet transforms application in power systems

Abstract: Wavelet transform has received great attention in power community in the last years, because are better suited for the analysis of certain types of transient waveforms than the other transforms approach. This paper presents a descriptive overview of the wavelet transform applications in power systems. The main publications carried out in this field have been analyzed and classified by areas. A list of 116 references is also provided.

A Traveling-Wave-Based Amplitude Integral Busbar Protection Technique

Abstract: This paper proposes an extra high-speed busbar protection technique according to the propagation theory of traveling wave. When the fault occurs on the busbar, the detected initial traveling waves on all connected lines will come from their back, which are defined as positive direction traveling waves. While a fault occurs on any one of these lines, the detected initial traveling waves on all healthy lines are positive direction traveling waves; however, the traveling wave direction on the faulted line is negative. Within a short duration of postfault, a criterion discriminating fault direction can be established according to the amplitude integral relationships between the positive direction traveling wave and the negative direction traveling wave. Analyzing the detected traveling wave directions for all lines, a distributed busbar protection scheme can be constructed. To evaluate the proposed technique, a typical busbar model was built. Simulation results show that the proposed method can rapidly and reliably discriminate the internal faults from external faults, and the protection performances are immune to fault resistances, fault inception angles, fault types, and current-transformer saturation.