Research And Design Of A Handheld Wireless Instrument For Phase Detecting

The phase detection of two period signals is commonly used in power system. In order to ensure the same way and the safe operation of the power grid in some cases, such as grid-connected of the new power plant, new construction, renovation, expansion of substations and transmission lines, and before transmission to the user, the phase detection must be done in three-phase circuit. However, the phase detection is a time-consuming and lab-intensive process, low safety factor, and the accuracy of measurement result must be high. The slightest mistake of phase detection can lead to an unstable power grid, causing a chain reaction resulting in serious consequences. As the size of grid is more and more big, the interconnection of power grid is more and more frequent, nuclear work also is particularly important.Based on the theory of phase detection, comparing with several phase contrast detection method, this paper minutely introduces the measurement principle of Fourier transform algorithm(FFT), and notes that the algorithm is easily cased large measurement errors because the grid frequency is likely to cause relatively minor fluctuations in actual measurement. Then, a mean filter algorithm which can improve the accuracy of phase difference measurement is proposed based on Fourier transform. Through analyzing the function of wireless phase detector, this paper designs and implements a handheld wireless system of the phase detection based on MSP430+FPGA controller. GPS timing, IEEE1588 clock synchronization protocol and local time using oven controlled crystal oscillator work together to ensure that time of the system is synchronous in different environments of phase detection. The wireless transfer module is reusable in remote controlling and intelligent data exchanging, combining the automatic transmission function of voltage and current detection range by relays, making its high accuracy and degree of automation.In consider of the power consumption and using complexity, high-performance Cyclone II FPGA chip IEP2C35F484I8 is used as the controller of clock synchronization and wireless data trans mission, and MSP430 microcontroller is used for data sampling and processing and human-computer interaction on hardware. Considering the detection precision, automatic shift mode is designed to change amplitude detection range on hardware. The system realizes IEEE1588 time synchronization protocol based o n the actual situation using wireless transmission module, and using the mean filtering algorithm which is based on Fourier transform algorithm on software.Eventually by full-scale testing the instrument performance, it is easily found that the instrument can complete the phase detection by wireless conveniently, safely, intellectually and efficiently.