Research Of Intelligent Synchronous Generator De-excitation Device Based On DsPIC

In the recent years, the unit capacity of generator set improves gradually in China. Rated excitation voltage and rated excitation current are also increasing. The energy in rotor flux must be transferred or eliminated rapidly when synchronous generator goes wrong so as to reduce accident and protect the generator set. So, higher requirements are put forward to protective generator de-excitation device. De-excitation device should not only perform reliably under several given conditions but also be easy to use and maintain. In this paper, synchronous generator intelligent de-excitation device is designed based on dsPIC digital controller. The classification principle is introduced in the de-excitation control, which improves the rapidity, safety and economy of de-excitation device.Firstly, this paper introduces the current situation and principles of several traditional de-excitation ways and de-excitation devices. Intelligent de-excitation device with linear resistor combination is studied deeply in this paper. Secondly, dsPIC30F6014 is used as the main control chip. The de-excitation device with intelligent computer technology can realize functions such as monitoring and displaying rated excitation voltage and rated excitation current, accessing secondary resistance by driving GTO appropriately so as to fulfill the rapid and safe de-excitation purpose.In addition, complete hardware and software flowchart design of the intelligent de-excitation device are given in this paper. The mathematical model of the process of de-excitation is established by using the MATLAB/Simulink tool. Curves of the excitation current and voltage and de-excitation time of several traditional de-excitation methods and intelligent de-excitation method are compared based on the parameters of The Three Gorges 700 MW hydroelectric generating set. The simulation results show that, this method overcomes the disadvantages of the existing complex and expensive de-excitation circuit. The intelligent de-excitation device has obvious advantages, such as rapidity, safety and reliability.