Power Frequency Measuring Method Based on Linear Interpolatio

In view of problems of complex design in hardware and big measuring error in software respectively existed in frequency measuring methods with hardware and software, the paper proposed a power frequency measuring method based on linear interpolation. Firstly, the method finds two nearest sampling points to the first zero-crossing point in half-wave and uses linear interpolation to calculate T1 between the zero-crossing point and the later sampling point. Then it finds two nearest sampling points to the next zero-crossing point in half-wave and uses linear interpolation to calculate T3 between the zero-crossing point and the former sampling point. And then it calculates T2 between the first sampling point and the latest one. At last, it calculates power frequency f by adding T1, T2 and T3. The test result showed that measuring error of the method is ±0.05 Hz with simple calculation process.