Research And Development Of Measuring Unit Of Excitation System Based On CAN Bus

Excitation system of synchronous generator plays an important role in improving the reliability and stability of power system nowadays. In our country the problems are: the connection among parts in excitation system is so tight it is easy to go wrong; it is difficult for maintenance and upgrade. In order to resolve the problems above mentioned, a kind of distributed excitation system based on CAN bus is constructed. It also gives detailed hardware and software design of measuring unit. In the design of hardware, it introduces the hardware of measuring unit, including the design of adjustor circuit, CAN interface circuit; it also introduces the software of measuring unit, the programs adopt C language and assemble language and use module design methods.Accurate AC parameters measurement is the base of excitation regulate and faults real-time monitoring and diagnosis, so, this paper discusses the theoretical basis for power, RMS, frequency and harmonic phase measurements of power system directly from the wavelet matrix transform dada associated with each sampling voltage and current element pair. Computer simulation result proves that the AC parameters measurement using the wavelet transform could get the accurate result by the ideal sampling situation, i. e. the synchronous error is zero.Excitation system faults are main causes of generator electrical emergency, it is necessary to carry out faults real-time monitoring and diagnosis in the excitation system. Detect early and avoid misadjusting is always the emphasis of excitation system research. Then the method of fault diagnosis in three-phase thyristor converter bridge based on spectrum analysis is discussed. And the fault model is simulated and analyzed through the SimPowerSystems under the Matlab/Simlink surroundings again in the method, also fault diagnosis criterion is gained in the condition.