Advantage to Short Circuit Current of Calculation on Power System by the MVA Method
Ming-Jong Lin *
Department of Electronic Engineering, Southern Taiwan University of Science and Technology, No.1, Nan-Tai St Yung-Kang Dist., Tainan City 710, Taiwan (R.O.C.).
*Author to whom correspondence should be addressed.
Abstract
The short circuit current of the equipment must be carefully calculated. If it is not effective to isolate the fault point, while the system is abnormal. That will leads to prolonged fault time and the instability of power system. The calculation process is very so complicated that must to establish any capacity of equipment on system. This article will introduce method of the traditional algorithm beginning. Next, to establish the basic principles of simplified procedures such as the capacity of two parallel devices are considered as a series method (plus), but the capacity of two series devices are considered as a parallel method to calculate. Finally, to calculate the fault short-circuits current based on the actual equipment capacity on the power system. Another technique is to transform the structure of transmission line from △ to Y so that it easy to simplify for calculation. It is proved to be a simple and easy to understand what method for short circuit fault current of calculation. The method can provide accurate and effective calculation of system short circuit capacity and current at each equipment point, so that designer can make appropriate specifications in design and procurement to avoid wasteful investment.
Keywords: Single - line diagram, per – unit system (P.U.), short circuit current, capacity