Research on Frequency Selection of Triple Frequency in Earth Capacitance Measurement

2017 ◽  
Vol 18 (3) ◽  
Author(s):  
Qiukuan Zhou ◽  
Jun Yao ◽  
Yan Liu ◽  
Yi Tan ◽  
Yang Zou ◽  
...  
Keyword(s):  
Distribution Network ◽  
Selection Method ◽  
Capacitance Measurement ◽  
Distributed Network ◽  
Frequency Method ◽  
Voltage Transformer ◽  
Frequency Selection ◽  
Triple Frequency ◽  
Zero Sequence ◽  
Measurement Principle

AbstractThis paper investigates a frequency selection method of triple frequency in earth capacitance measurement. Based on the researches about the triple frequency method, the measurement principle of the proposed method is presented in detail. In this paper, the accurate earth capacitance in the distribution network can be calculated by establishing corresponding equations with injecting three different frequencies of current signals to the triangle open-side of voltage transformer (VT). Furthermore, the influences of selected frequency on the calculated results of the capacitive current are further analyzed. In order to improve the measurement accuracy, the initial selected frequencies of injected zero-sequence current signal should be set small as the larger earth capacitance in the distributed network is more common. Then the value of selected frequency should be increased correspondingly with the small capacitance in the distribution network. Finally, the correctness of theoretical analysis and feasibility of frequency selection method are verified with the simulation and experimental results of the earth capacitance measurement in distribution network.

Research on Frequency Selection of Triple Frequency in Earth Capacitance Measurement

energyo ◽  
2019 ◽  
Author(s):  
Qiukuan Zhou ◽  
Jun Yao ◽  
Yan Liu ◽  
Yi Tan ◽  
Yang Zou ◽  
...  
Keyword(s):  
Capacitance Measurement ◽  
Frequency Selection ◽  
Triple Frequency ◽  
Selection Of

scholarly journals Single-phase-to-ground Fault Line Selection Method Based on STOA-SVM

2021 ◽  
Vol 2095 (1) ◽  
pp. 012029
Author(s):  
Yicen Liu ◽  
Xiaojiang Liu ◽  
Songhai Fan ◽  
Xiaomin Ma ◽  
Sijing Deng
Keyword(s):  
Single Phase ◽  
Distribution Network ◽  
Ensemble Empirical Mode Decomposition ◽  
Selection Method ◽  
Support Vector ◽  
Ground Fault ◽  
Mode Decomposition ◽  
Before And After ◽  
Zero Sequence ◽  
Line Selection

Abstract In view of the complex characteristics of nonlinearity and non-stableness of the zero-order current of each line after the single-phase ground fault of the distribution network, a distribution network fault selection method based on Sooty Tern Optimization Algorithm(STOA) and the combination of support vector machine is proposed. At first, the zero-sequence current before and after fault is obtained, then five kinds of IMFs including different components are obtained by ensemble empirical mode decomposition, and the energy entropy of the fault transient zero-sequence current is obtained by Hilbert transform, the results of training and testing are obtained by inputting the feature vector. The simulation results show that the accuracy of the proposed line selection model is 97.5%.

scholarly journals Application of frequency optimization neural network method on power line communication

2021 ◽  
Vol 300 ◽  
pp. 01018
Author(s):  
Xinyu Xi ◽  
Dehong Li ◽  
Dongwen Chen ◽  
Yong Li
Keyword(s):  
Neural Network ◽  
Distribution Network ◽  
Selection Method ◽  
Power Line ◽  
Optimal Frequency ◽  
Actual Distribution ◽  
Frequency Selection ◽  
Power Line Carrier ◽  
Point Set ◽  
Carrier Communication

The quality of broadband power line carrier communication mainly depends on the carrier communication frequency. However, there is a lack of fast and effective optimal carrier frequency selection method. One frequency selection method based on frequency point optimization neural network is proposed by this paper. This method combines transmission line theory and voltage partial reflection theory to build a power line carrier channel mathematical model of the distribution network. The input frequency point sample set is used as the training set of the frequency point optimization neural network to obtain a neural network model that can predict the local optimal frequency point set. Then the actual distribution network is taken as an example for simulation analysis. When inputting any frequency range, the model outputs the corresponding optimal frequency point set. Simulation results show that the algorithm saves a lot of input impedance or channel strength testing time, while the error rate is limited to about 3%.

scholarly journals A novel fault section locating method based on distance matching degree in distribution network

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Zhenxing Li ◽  
Jialing Wan ◽  
Pengfei Wang ◽  
Hanli Weng ◽  
Zhenhua Li
Keyword(s):  
Single Phase ◽  
Distribution Network ◽  
Matlab Simulink ◽  
Grounding Resistance ◽  
Blind Zone ◽  
System Transition ◽  
Transition Resistance ◽  
Zero Sequence ◽  
Matching Degree ◽  
Amplitude Characteristics

AbstractFault section location of a single-phase grounding fault is affected by the neutral grounding mode of the system, transition resistance, and the blind zone. A fault section locating method based on an amplitude feature and an intelligent distance algorithm is proposed to eliminate the influence of the above factors. By analyzing and comparing the amplitude characteristics of the zero-sequence current transient components at both ends of the healthy section and the faulty section, a distance algorithm with strong abnormal data immune capability is introduced in this paper. The matching degree of the amplitude characteristics at both ends of the feeder section are used as the criterion and by comparing with the set threshold, the faulty section is effectively determined. Finally, simulations using Matlab/Simulink and PSCAD/EMTDC show that the proposed section locating method can locate the faulty section accurately, and is not affected by grounding mode, grounding resistance, or the blind zone.

scholarly journals Neutral-Point Voltage Balance Control of Three-Level Converter Based on Selection Method of Dynamical Adjustment for Small Voltage Vector

2021 ◽  
Vol 11 (11) ◽  
pp. 5076
Author(s):  
Hongyan Zhao ◽  
Yan Li ◽  
Fei Lin ◽  
Yian Yan
Keyword(s):  
Balance Control ◽  
Harmonic Distortion ◽  
Selection Method ◽  
Neutral Point ◽  
Voltage Vector ◽  
Unbalanced Voltage ◽  
Zero Sequence ◽  
Ac Current ◽  
Level Converter ◽  
Small Voltage

The balance control of neutral-point voltage (NPV) is important in the three-level converter. In this paper, this problem is studied by taking the VIENNA circuit as an example. The deviation of NPV is essentially caused by mismatch between the charging and discharging time of two series capacitors by the neutral-point current flowing into or out of the DC side. The unbalanced NPV will lead to unbalanced voltage stress of two capacitors and power switches and may cause overvoltage damage to both and also increase the total harmonic distortion (THD) and harmonic components in the AC current. In this paper, by analyzing the role and effect of a small-voltage vector on NPV, a control strategy based on the selection method of dynamical adjustment for a small vector is proposed. By judging the fluctuation of NPV, different small vectors are dynamically selected to act to adjust the NPV. For verification, the proposed strategy is compared with the traditional zero-sequence voltage injection (ZSV-J) method through simulation and experiment. Compared with ZSV-J, the THD of AC current is decreased by about 27.2%, the efficiency is increased by about 1.66%, and the adjustment speed of NPV is increased by about 50%. Therefore, the feasibility and advantages of the strategy are verified.

A Skywave OTHR Adaptive Frequency Selection Method Based on Preliminary Criterion and Weighted Criterion

2014 ◽  
Vol 1061-1062 ◽  
pp. 974-977
Author(s):  
Shi Hua Liu ◽  
Xian Gang Liu ◽  
Zhi Jian Sun
Keyword(s):  
Selection Criterion ◽  
Selection Method ◽  
Frequency Selection ◽  
Selection Of

A skywave radar adaptive frequency selection method based on the preliminary criterion and the weighted criterion is presented. In this method, according to the various operational tasks, the frequency selection criterion is divided into the preliminary criterion and the weighted criterion based on the characteristic of the targets. The adaptive frequency selection of the skywave radar is achieved by the weighted computed of the frequency selection criterion. The feasibility and availability is demonstrated by an example.

Voltage Imbalance Simulation for Distributed Network with Single-Phase PV Connected

2014 ◽  
Vol 687-691 ◽  
pp. 3166-3170 ◽  
Author(s):  
Li Sheng Li ◽  
Shi Dong Zhang ◽  
He Jin Liu ◽  
Xing Quan Ji ◽  
Gui Bin Liu ◽  
...  
Keyword(s):  
Power Distribution ◽  
Single Phase ◽  
Distribution Network ◽  
Distributed Network ◽  
Power Distribution Network ◽  
Point Tracking ◽  
Power Point Tracking ◽  
Conductance Method ◽  
Power Point ◽  
The Impact

There exist many single-phase photovoltaic generations in modern power distribution network, and these distributed sources may be in a certain extent affect the symmetry of voltage. To investigate the impact of photovoltaic generation on quality problem of distribution network, mathematical and digital model of photovoltaic power generation are built in this paper, and the maximum power point tracking control is simulated based on incremental conductance method.

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