This paper presents a distributed feeder automation algorithm based on local topology, considering switch action failure, communication failures and other confounding factors. This makes higher efficiency of data proc...
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A forecasting model of the gradual optimization algorithm is established to predict substation grounding grip corrosion rate. In this model, according to the "Over Fitting" phenomenon in the neural network l...
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Distributed generation (DG) injects new vigor into the power system, but it sometimes brings unfavorable factors influencing the power quality of distribution network. In this paper, the Dynamic Voltage Restorer (DVR)...
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Distributed generation (DG) injects new vigor into the power system, but it sometimes brings unfavorable factors influencing the power quality of distribution network. In this paper, the Dynamic Voltage Restorer (DVR) is introduced to the distribution network to improve the power quality. In view of that the detection of voltage compensation is the key factor that influences the effect of voltage compensation, a voltage direct detection method based on mathematical morphology is proposed. Firstly, the positive-sequence voltage with harmonics can be extracted by the instantaneous sequence-component decomposer. And then the harmonics is filtered by mathematical morphology filter. Lastly, the control variable of voltage compensation needed by DVR can be calculated from the voltage direct-detecting algorithm. The simulation results show that this method has the characteristics of favorable accuracy, real-time performance and simplicity, and assures the voltage quality of load side after compensation by DVR.
Zero-sequence harmonics caused by nonlinear loads usually result in high voltage distortion levels throughout the facility, neutral conductor overloading, motor heating, transformer heating, increased losses, and exce...
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Zero-sequence harmonics caused by nonlinear loads usually result in high voltage distortion levels throughout the facility, neutral conductor overloading, motor heating, transformer heating, increased losses, and excessive harmonic injection onto the utility supply system. This paper presents a novel method to eliminate zero-sequence harmonics by using Zero-sequence Resister Block (ZRB) and Zig-Zag transformer. Zig-Zag transformer is a special connection of three-phase transformerpsilas windings. The ZRB is also a special connected transformer, whose three windings are wounded in the same core. The ZRB has zero reactance for positive and negative-sequence components but giving three times of self-reactance for zero-sequence reactance. In this paper, an analysis is carried out; simulations and laboratory tests are used to evaluate the performance of the Zig-Zag transformer and ZRB under various system conditions. The simulation and laboratory test results indicate that the combination of ZRB and Zig-Zag transformer as filter is a better and effective way to attenuate the neutral current, which also provides an innovational way to improve power quality.
The radiation and propagation of electromagnetic (EM) waves generated from PD caused by the obstruction of main transformer components are studied by FDTD simulation in order to get more information for PD location an...
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The radiation and propagation of electromagnetic (EM) waves generated from PD caused by the obstruction of main transformer components are studied by FDTD simulation in order to get more information for PD location an...
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The radiation and propagation of electromagnetic (EM) waves generated from PD caused by the obstruction of main transformer components are studied by FDTD simulation in order to get more information for PD location and diagnosis. Current filament, perfect conductive cylinder and perfect conductive spiral coil models are used to simulate the radiation and the influences of iron-core and transformer coil to the propagation of EM waves. The results demonstrate dynamic propagation process of EM waves in time order, and prove the correctness of the shortest optical path principle. But the attenuation and distortion of EM waves-especially the first peak amplitude-caused by the obstruction of large solid conductive obstacle like iron-core are quite intensive that it may cause great difficulties to identify exact arriving time position of incident waves coming along the shortest optical path. While the influences of the coil to the propagation of EM waves are so little that HF EM waves can penetrate it in almost linear path.
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