A new method of power calculation based on parallel inverters

The Orthogonal extraction approach of power calculation uses orthogonal characteristics of trigonometric function to extract fundamental voltage and current to compute power. It ensures the precision of power calculation. However, there are integral factors causing at least delay of one fundamental period, and using the sine and cosine tables during digital control process leads to quantitative errors and the occupancy of DSP space. The improved orthogonal extraction method by introducing sliding window function decreases greatly delay time, but there is imprecise power of a fundamental period for mutation load. Therefore, it is a compromise way between the rapidity and precision. In this paper, a new computing power approach is introduced. It is able to calculate real-time power, and only one sampling cycle is needed to obtain the true value of the power for mutation load.. It occupies much smaller DSP space because of the absence of sine and cosine tables and cuts down greatly calculation. The simulation is made and the correctness of the method is validated.