Dong Xinzhou

Bio: Dong Xinzhou is an academic researcher from Tsinghua University. The author has contributed to research in topics: Fault (power engineering) & Fault indicator. The author has an hindex of 10, co-authored 33 publications receiving 269 citations.

Fault position relay based on current travelling waves and wavelets

Abstract: The current travelling wave is utilized to detect the fault position in the transmission lines in this paper. How to identify the incident travelling waves and reflected ones from the fault point when noises exist is discussed and resolved. A fault position relay based on current travelling waves and wavelets theory is designed. The relay's principle is mainly on wavelet theory and modulus maxima of the wavelet transform. By analyzing the distribution of the modulus maxima, different components in the current travelling waves can be distinguished and then the incident and reflected travelling waves are identified and finally useless components are filtered. The incident and reflected travelling wave's time difference arrival time difference indicates the fault position. An EMTP simulation example is illustrated. The relay is been proved correct and effective.

Cause analysis on large-scale wind turbine tripping and its countermeasures

Abstract: Several large-scale wind turbine tripping accidents occurred in Jiuquan wind power base in 2011. According to the on-site survey and the oscillogram analysis,the cause of these accidents is the short-circuit fault of electrical equipment and cables in wind farm,which leads to the voltage drops in the farm and system,therefore a large number of wind turbines trip because they do not have the low voltage ride through(LVRT) capability. After the fault is cleared,a large number of wind turbines trip again when the system voltage rises to setting point of overvoltage of wind turbine,because the reactive power compensation device in wind farm step-up substation can not timely regulate the voltage automatically. Accordingly,wind turbine retrofitting and collector system and its protection configuration improvement are put forward from a practical point of view,and combining with the characteristics of large-scale wind power base,the subjects to prevent wind power reasonably from large-scale tripping are also put forward for further research.

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.

Optimizing solution of fault location

Abstract: This paper describes an assembled transmission line fault location algorithm based on one-terminal electrical quantities. It uses a fault location algorithm based on measurement impedance to calculate a fault section of a transmission line, then it uses a wavelet transform fault location algorithm based on current traveling wave to pinpoint the fault position. This algorithm deals with the conflict between accuracy and robustness of fault location algorithm successfully. The computer simulation demonstrates that the assembled fault location algorithm holds high robustness and high accuracy.

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.

Improved single-ended traveling-wave fault-location algorithm based on experience with conventional substation transducers

Abstract: Single-ended unsynchronized traveling-wave fault-location algorithms have been around for several years. They avoid the costs and complexities associated with remote-end synchronization. Nevertheless, there is a corresponding increase in required signal processing as each reflection must be identified and then related in time to the signal wavefront. The current signal processing techniques include a combination of modal and wavelet analysis, where the resulting vectors are often squared. However, the performance of this process degrades dramatically with the filtering associated with the substation transducers and secondary circuits. Furthermore, the variation in observed reflection patterns demonstrates that these methods cannot adequately distinguish between faults on the near, or far half of the transmission line. This paper considers the traveling-wave data observed on a 330-kV transmission system and presents a new signal processing methodology to cater for the observations. This is based on the continuous wavelet transform that is calculated at a suitably large scale. The polarities of the resulting coefficients are used to confirm the nature of the fault and to infer the true fault location.

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.

A Communication-Assisted Protection Strategy for Inverter-Based Medium-Voltage Microgrids

Abstract: This paper proposes a communication-assisted protection strategy implementable by commercially available microprocessor-based relays for the protection of medium-voltage microgrids. Even though the developed protection strategy benefits from communications, it offers a backup protection strategy to manage communication network failures. The paper also introduces the structure of a relay that enables the proposed protection strategy. Comprehensive simulation studies are carried out to verify the effectiveness of the proposed protection strategy under different fault scenarios, in the PSCAD/EMTDC software environment.

Hybrid Fault Diagnosis Scheme Implementation for Power Distribution Systems Automation

Abstract: Power distribution automation and control are important tools in the current restructured electricity markets. Unfortunately, due to its stochastic nature, distribution systems faults are hardly avoidable. This paper proposes a novel fault diagnosis scheme for power distribution systems, composed by three different processes: fault detection and classification, fault location, and fault section determination. The fault detection and classification technique is wavelet based. The fault-location technique is impedance based and uses local voltage and current fundamental phasors. The fault section determination method is artificial neural network based and uses the local current and voltage signals to estimate the faulted section. The proposed hybrid scheme was validated through Alternate Transient Program/Electromagnetic Transients Program simulations and was implemented as embedded software. It is currently used as a fault diagnosis tool in a Southern Brazilian power distribution company.

Identifying Single-Phase-to-Ground Fault Feeder in Neutral Noneffectively Grounded Distribution System Using Wavelet Transform

Abstract: A scheme of single-phase-to-ground fault feeder identification in distribution networks with the application of a wavelet transform technique is presented in this paper. The scheme uses zero-sequence current traveling waves to identify the faulted feeder, and the busbar residual voltage to determine an event caused by fault or switch operation. The current traveling waves measured by zero-sequence current transducers are decomposed using wavelet multiresolution analysis. The local modulus maxima of the wavelet transform are extracted to determine the time of the initial traveling wave. The wavelet transforms on all feeders at the time are compared in magnitude and polarity with each other to identify the faulted feeder. The feeder identification is independent of the network neutral-point grounding mode. The proposed scheme was implemented and verified using Electromagnetic Transients Program (EMTP)-generated signals. The scheme proved to be robust against transients generated during normal events, such as feeder energizing and de-energizing as well as capacitor bank switching.