| In recent years, the demand for electric power has leaded to an accelerated increase as well as the power quality with the development of China, which provides a strong imputes to the fast national economy growth. The constant improvement in power market, also puts forward a higher requirement on the standardization of power quality, which makes the power quality as a key factor in power market,and has caused wide public concern. Therefore, the research on information collection and intelligent monitoring system for electric power will be of great practical significance.The multi-function information collection and intelligent monitoring system studied in this project, is to take the 32-bit DSP TMS320F2812 application of advanced technology as the core, and a MCU PIC18F458 as an accessory. The system can simultaneously collect information of three-phase current and voltage signals throughout the power network, also performs a real-time harmonic analysis, and figures out basic power quality parameters, and then makes warning judgment according to the results. Via the system user interface, users can not only obtain required information, but set the system parameters at will and even appoint the system to transfer the data of power network onto distal PCs for further processing through expanded Ethernet interface.The completion work in this paper can be divided into two parts: one is the design and realization of system hardware; the other is that of software module as well as improved algorithm based on system hardware.TMS320F2812 works as the core of the system. It mainly takes charge of the detection and sampling circuit for implementing quasi-synchronous sampling algorithm, performs real-time processing on sampled data, inspects external keyboard inputs, and also it needs to control the communication with MCU PIC18F458 and the Ethernet as well. Meanwhile the MCU PIC18F458 works as an accessory of TMS320F2812. It is designed to drive the LCD for reducing TMS320F2812's computational burdens.On the basis of the system hardware, the system software has done the following jobs: ADC module on-line self-calibration algorithm, realization of Quasi-synchronous sampling algorithm, realization and the improvement of FFT, realization of the RFFT algorithm, efficient realization of 32-bits division algorithm and the application of fast inverse square root algorithm for calculating RMS(root mean square) values. It is better to say that FFT algorithm can be implemented with efficient assemble codes and hereafter certain improvement still can be made in three aspects, including twiddle factor pre-storage, bit reverse order algorithm and first two stages of butterfly packed algorithm, which can effectively improve FFT function by 10% at any rate. What's more, a further improvement called RFFT (Real FFT) can be achieved as follows: First, the N point sampled real signal of power network is divided into two parts such as odd sequence and even sequence. Second, the two sequences will be used to form an N/2 point complex signal sequence. Third, an FFT calculation can be performed based on N/2 point complex sequence for a FFT result sequence. In the end, the result sequence will be applied to construct the FFT result sequence as for the former N point real signal. Accordingly, the RFFT can be implemented and an improved performance has been mostly reported by 40%.The ability of data processing and real-time response of the system have improved prominently compared to the traditional power quality measuring equipment. And experimental results indicate that system runs stably, have good real-time performances and high measurement accuracy. |
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