Ultra-short Circuit Protection And Research

Relay protection is one of device to respond the fault and abnormal operation state of electric power system, to make the breaker action and to send out the signal. With the development of the electric power industry, the structure of low-voltage distribution network and the customer property change greatly and also set higher requirements for protective relay device. The traditional stage type current relay protection what is widely used in low-voltage short transmission line, is setting difficulty and easy to action without sequence. It is very difficult to satisfy the demands of modern power system development.This topic analyzes the characteristics of low-voltage short transmission line fault and the methods of relay protection used in this field on the basis of summarizing the present research situation. Many offshore petroleum platforms of Shengli Oli Field adopt chain shape, single power supply and short distance between platforms. In the transformation of protection we propose a new protection based on interlocking between impedance relay and distance relay with new criterion. Compared with common distance protector, the principle of this device is simple and the quantity of the relay is reduced greatly.This new distance relay can react single-phase and two phase short circuit with one and the operating principle of the distance relay is simple and visual. Analysis results indicate that the distance relay with strong resistance transition resistance capacity, a clear direction in low-voltage, and good character. In addition this text has improved the impedance relay too, merge three the whole impedance relays into a relay and make the device simpler.At the same time, this paper puts forward the computer relay protection scheme of low-voltage short transmission line, design the software and the hardware of data acquisition system. Because DSP has prolific hardware...