| Power load is rising, increasing the load density, makes the distribution network has been played in a city bridge connecting link in thevoltage of 10 kV medium voltage distribution, and some not meet the requirements ofpower development,20kV voltage level and is now in the international emergence of new features. China has also been included in the national standard voltage, the purpose is to improve primary distribution voltage. Its role will be to replace the 10kV, directly to the 380V power supply, while abolition of 35kV,110kV obtained directly from the power supply system for the formation of 110/20/0.38kV. This can be achieved not only improve the effectiveness of distribution voltage, andaccess to simplify the effect of voltage levels.This paper introduces the 20kV distribution voltage leve of the domestic and international developments, and then describes the advantages of 20kV power distribution running and characteristics of 20kV protection configuration. Analysis of the Neutral, the low resistance grounding and arc suppression coil grounding through the advantages and disadvantages of three ways, using MATLAB simulation under different single phase grounding fault in the operation. Discusses the 20kV distribution network the choice of neutral grounding requirements. Zero sequence current from the general rules setting calculation leads to 20kV and the composition of zero sequence protection setting calculation, gives the zero-sequenceⅠ,Ⅱ, and the main transformer zero sequence segmentsⅠ,Ⅱsection of the program setting.Zero sequence current protection in the short-term or complex circle, the liquid is very small section of the scope of protection, to achieve full line rate move, proposed based on SVM (support vector machine) 20kV single-phase ground fault detection, and modeling with MATLAB mixed lines and cable lines were verified pure. |
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