Research For Rotor Windings' Grounding Detection Of Brushless Synchronous Electrical Machine

Synchronous electrical machine is one of the most important equipments in electric power system. Due to the restriction of its size, rotor structure is rather compact. As a result, the insulation of the rotor windings can't be strong. Meanwhile, rotor windings have to bear large mechanical stress and electrical stress when synchronous electrical machine in operation. Therefore, the insulation of rotor windings can be probably destructed, which often leads to the grounding fault of rotor windings.When one-point grounding fault of synchronous electrical machine's rotor windings occurred, it can't form a loop to the ground, and the excitation loop can still maintain normal state and synchronous electrical machine can continue operate. But if it isn't dealt with in time, once another grounding fault occurred, then it forms two-point grounding fault, this kind of grounding fault is an extremely dangerous short circuit fault. At present, the grounding detection of synchronous electrical machine's rotor windings mainly aims at synchronous electrical machine with brush, but the grounding detection of rotor windings as to brushless synchronous electrical machine isn't ideal enough, so it need further research.This paper's work mainly revolves around the grounding detection of rotor windings of brushless synchronous electrical machine. Firstly, it introduces the existent methods of grounding detection of rotor winding of synchronous electrical machine with brush, and sums up their advantages and disadvantages. Secondly, it analyzes the structure of blushless synchronous electrical machine and excitation method from a whole view, considering the special structure of brushless synchronous electrical machine, a novel grounding detection method of rotor windings of brushless synchronous electrical machine is put forward in this paper---resistance-bridge with source, which adopts ATmega16L single chip as the core of grounding detection system. The principle of this method is simulated in real time with powerful Matlab6.5/Simulink6.0, and its hardware and software is designed, the simulation result demonstrated that this detection theory is correct, so it can be applied to the grounding detection of rotor windings of brushless synchronous electrical machine. In order to test the simulation data's correctness, an analog experiment of resistance-bridge with source is carried out, the experiment data corresponds the simulation data.Considering the limited time and the grounding detection system's complexity, this paper's emphases are the follows: analysis of insulation inspection theory; analysis of grounding detection simulation, hardware and software design of grounding detection system in principle.What was been studied in this paper provided a certain theory reference basis and actual engineering method for the actual grounding detection system of brushless synchronous electrical machine.