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Transformers neutral grounding accessing small reactance is an effective measure to restrain short circuit current in 500kV power grid. But accessing small reactance will bring changes to the zero-sequence parameters of system. The relay protection, especially the main transformer protection and transmission line protection nearby will be affected and act incorrectly when unsymmetrical earth fault...
In this paper we show that the HVDC converter transformer valve side has the diversity and space-time discrete. Considering the influence of failure time on the fault feature, this paper proposes a method of fault feature stage dividing. The basis of fault feature stage dividing is given, and simulation result is showed for comparison. The protection test and BPP strategy research is also discussed...
An active catalyst of Ag/γ-Al2O3 was prepared by impregnation method. The main components of the catalyst were characterized by X-ray diffraction (XRD). A non-thermal plasma (NTP) reactor was designed based upon dielectric barrier discharge and the non-thermal plasma assisted catalyst (NPAC) system was established. The bench test was carried out and the reduction of diesel engine harmful emissions...
In recent years, much attention has been paid to the problem of farmland soil contamination by heavy metals in China. Cadmium (Cd) is an important heavy metal which can cause adverse ecological effects, in particular, can be easily accumulated by rice plants. On the basis of determining the concentrations of Cd in 303 farmland soil samples from the rice producing area in the Luxian County, Sichuan...
This paper establishes a simulation platform of large scale power grid with multi-infeed DC using EMTDC, in order to analyze the interaction of AC/DC systems and its influence on protective relaying. The principles and methods of the models adoption, the scale of power system, network simplification and data processing are dealt with to balance the simulation demands between precision and efficiency...
In this paper, a novel geometric features extraction method for facial expression recognition is proposed. ASM automatic fiducial point location algorithm is firstly applied to a facial expression image, and then calculating the Euclidean distances between the center of gravity coordinate and the annotated fiducial points' coordinates of the face image. In order to extract the discriminate deformable...
Aiming at the problem in facial feature location, the Active Shape Models algorithm has no evaluable criterion to judge its convergence, and tend to run into local minimum when using the fixed search scale, and how to choose the scale is always an issue. This paper presents a method based on the whole shape gray grads to evaluate the search effects, and an improved search policy of multiscale. The...
The traditional Gabor transform need calculate convolution with whole image when extract expression feature. So, the feature dimensions are very large and computation complexity is very high. Though some improved methods can reduce the feature dimensions and computing cost by manually marking out the feature points, but those methods need intense human intervention and can not meet to the need of...
The pulse capacitor, as the important energy storage device, its stability will directly influence the dependability of the pulse power system that capacitor located in. Life-span of the capacitor has strong relationship with its working dependability, In this paper, by charging and discharging to the pulse capacitor and testing direct current partial discharge to the capacitors at different stage...
This paper gives a new more practical software reliability model based on architectures of software components. This model uses semi-Markov chain and can give the quantitative evaluation about the digital protection's software. It analyzes the relation between the material architecture of software's modules and the reliability of software then changes the model into a semi-Markov one based on the...
As one of the primary methods, the impedance fault location one based on the single-terminal data is widely used. But for easily infected by the operation condition of the opposite system, it is difficult to estimate accurately. Thus this paper puts forward to a novel nonlinear-estimation algorithm using the characteristics of arc. According to the equivalency of the sequence component of harmonic...
Taking the data acquisition system (DAS) for example, the paper presents a new approach to study the hardware reliability of digital protection devices. A significant feature of the approach is that it combines the circuit simulation function of OrCAD/PSpice software and Monte Carlo simulation method. According to reliability criterion presented in this paper, it obtains two reliability indices, namely...
Near real-time transfer of GPS common-view data is no longer a problem, but near real-time data processing of the data still calls for study, because it is not yet achieved by the usual smoothing and filtering techniques. Based on the characteristics of the GPS common-view data, a Kalman filtering algorithm is designed for estimating the time difference between two sites, while greatly reducing the...
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