Development Of Short Circuit Current Calculating Softwore For WuHai Electrical Power Network

Short circuit the serious fault in power systems. The different fault types, location and duration of short circuit can lead to the results, which is either the failure of normal power supply in the local area, or the breakdown of the entire power system. With the development of national economy, the structure of power systems is more and more complicated, so that the security and stability of power systems are becoming more and more important. Presently in most national power departments, short circuit current is calculated by handwork or using the short circuit current calculation software which is based on DOS operation system. The former has low precision, need large workload and is fallible. And the latter ,even though has great function, but it is unpractical because of its inconvenient user interface. To meet the requirements of security and stable operation of modern power systems, and improve the speed and precision of calculation of relay protection equipments, a short circuit current calculation software is developed for Wuhai power network by Wuhai Electric Power Bureau and Electrical and Automation Engineering School of Tianjin University in 2003. Using this software, users can set the modes of operation by themselves, and without regard to the effect of loads, the short circuit current and bus voltage which users want to know are calculated when power network is in simple fault. 10kV and 35kV buses and bus interconnections can be satisfied to the short circuit calculation, and the development of Wuhai power network is considered in the design of database.The short circuit current calculation software for Wuhai power network includes: Data Processing System, Network Simplified System, Short Circuit Calculation System and User Interface. Bus admittance matrix is used to describe the structure of actual power network, Gaussian elimination is used to simplify the network, and short circuit calculation is based on symmetrical component method and superposition principle. This thesis shows how to process units of power systems, how to simplify the network, short circuit calculation principle, how to process mutual-inductance lines and the algorithm realization, then part of Wuhai 110kV power network is used to test the software. In this software, Windows interface is used, at the same time, its precision is high, operation is convenient and power network parameters are managed by the database. So it is friendly and practical short circuit calculation software.