Frequency Measurement Of The Low Frequency Electrical Signal

With the rapid development of the power system, whether industrial or military,the requirements of electrical signal processing have become more and more accurate. More attention has been paid to the frequency of the electrical signal, because it is always an important indicator of the electrical signal. Thus the requirements of frequency measurement accuracy are getting higher and higher.This paper discusses the design of a low-frequency electrical signal frequency measurement algorithm. The design is based on the FPGA and NiosII. Due to powerful logic control ability and digital processing capabilities, the FPGA is as the control center for the entire system.At the same time, the paper gives the main circuits.Firstly, the background and significance of the issue are introducted. Due to the shortcomings of the zero-crossing detection method and the Fourier transform method of measuring the frequency of the low-frequency electrical signals, the algorithms of filtering and linear interpolation method, and fitting the straight-line improved method are given.It makes up for the measurement accuracy and anti-jamming of the traditional zero-crossing detection method. It’s simpler algorithm than the Fourier Reform.Secondly, hardware system for measuring fitting the straight-line method is designed.Then all the modules of hardware system are given.Thirdly, the paper gives the customized solutions of soft-core in SOPC and top-level schematic diagram in the QuartusII. The hardware and software system for measuring fitting the straight-line method is built.The fitting the straight-line method is tested in the system. It confirms that fitting the straight-line method can be used in embedded systems and power systems.Finally, compare the zero-crossing detection method, the Fourier transform method, fitting the straight-line method, fast frequency measurement method, the look-up table frequency method, filtering and linear interpolation method, and fitting the straight-line improved method by the Matlab simulation results. By comparison, fitting a straight line method, fast frequency measurement method,the look-up table frequency method filtering and linear interpolation method, and fitting the straight-line improved method measuring the frequency of the low-frequency electrical signals have high accuracy, strong anti-interference.