Noise Analysis And Noise Reduction In Data Acquisition Of Power Grid

Data acquisition system of power grid provides an effective measure to monitor and diagnose faults for power grid, and is the core tool of building Strong Smart Grid in China. With monitoring power grid in real time, it will be reducing the input of manpower (human resource), and also improving real-time and accuracy of fault diagnosis and treatment, meanwhile, promoting the level of intensive management of power grid. Obviously, the performance determines the accuracy and validity of power grid dynamic monitoring. In the application process, however, the data is inevitably influenced by various noise sources, which would firstly impact the performance of high-speed, accuracy, and stability of system, then affect compression, reproduction of the power grid data, fault diagnosis, and other key functions. Therefore, , it is essential to classify the noise sources and analyze the characteristics of noises by a variety of simulation tools and experiments, and reduce noise at early stage based on the results of noise analysis during the design process of data acquisition system of power grid.This thesis is based on actual data acquisition of power grid, firstly points out possible noise sources and the effects through analyzing the hardware structure, work process and signal flow. And then, considering the analog acquisition circuit that mainly based on operational amplifier circuits affects the accuracy of system, the noise of circuits and the influence of the noise to data acquisition and data compression are analyzed combined with PSpice. After the analysis of operational amplifier, bring forward the selection method of operational amplifier in the design process of low noise circuits. Furthermore, aiming at the system level of data acquisition system of power grid, the model of noise of phase locked loop (PLL), which frequently used in the frequency synthesis of internal FPGA, power grid frequency tracking and synchronous sampling clock generator, is established by Simulink. The effects of independent time jitter and accumulated time jitter to data acquisition of power grid are also analyzed. Finally, the problems induced by signal integrity may be encountered when designing the high-speed digital circuit in data acquisition of power grid. So the signal integrity problems like single network signal quality of critical network and crosstalk by multiple networks to critical network are analyzed by HyperLynx. Noise reduction methods are provided and verified by simulation results.The research comes to some methods of noise reduction in data acquisition of power grid, which suggests a theoretical basis to promote the system performance and perfect the system design.