Design of Improving Bus Short Circuit Residual Voltage Based on Reactive Power Regulation of Synchronous Motor

Abstract

When a short circuit fault occurs in a power system, the short circuit current value in the short circuit increases greatly, and at the same time, it will reduce the voltage in the power network, even 60 percent to 70 percent of the original voltage, then the power of some users was destroyed. In order to make the system work properly, it is important to analyse the cause of bus voltage drop. The traditional solution is to increase reactive power by using external equipment, such as static capacitor or STATCOM device, but the cost of the above two devices is too high. And each bus bar lower end of the load is connected with synchronous motor in Xindu Chemical 110kv Substation. When a short circuit fault occurs in the system, the synchronous motor can be excited in a short time to reduce the voltage drop, which is economical and fast. In this paper, four excitation modes of synchronous machine are analysed in detail, including constant excitation current, constant reactive power excitation, constant power factor excitation and constant active power excitation. Finally, the constant active power excitation model is chosen to solve the problems encountered. Finally, the short circuit current is judged quickly, so that the short-circuit fault can be judged quickly according to the change rate of the current in the system.