Design And Research Of Digital Integrator In Rogowski Coil Electronic Current Transfromer

With the development of power system, the need of electrical measurement keep increasing. Being a new kind of current transformer, Rogowski Coil Electronic Current Transformer is researched more and more. Integrator is an important part of the current transformer, and its function directly affect the whole transformer. This article’s purpose is to design a digital integrator applied with Rogowski Coil, deeply analyse the digital integration algorithm and all kinds of error. So it can find a new effective way to eliminate the DC error during integrating and improve the reliability, stability and integrationFirstly, some kinds of digital integration algorithm are analysed. The result shows that compound trapezoid algorithm suits the high level of accuracy requirement. Then the error’s origin, effect and elimination method of digital integrator are analysed. It shows that the noncumulative error, such as the initial value of integration, and the accumulative error, such as the DC error, make up the total integration error. The mirroring method, which is a new method of DC error elimination, is put forward. And the final digital integrator is made up with the compound trapezoid algorithm, the mean value compensation method and the mirroring method. Finally, after the simulation of the digital integrator, the DSP is used to make the digital integrator came into realily, and the hardware is tested with the input of steady current, dynamic current, inferior harmonic current and high-order harmonic current.The simulation and hardware test shows that the mirroring method can eliminate most part of DC error without zoom in or out the needed part of the input signal. The digital integrator, which contains the use of the mirroring method, give out an output with accepted amplitude and phase accuracy under different kinds of input.