Electric Energy Measurement Based on the Improved Instantaneous Reactive Power Theory

In this paper, a method of electric energy measurement based on the instantaneous reactive power theory is put forward according to the deficiency that power under different frequencies will be offset at the same time under the nonsinusoidal and unbalanced condition. By changing the rotation direction and velocity of the p-q coordinate system in the generalized three-phase instantaneous reactive power theory, we can obtain the positive and negative sequence voltage and current of any harmonic in the three-phase three-line system. Then the positive and negative sequence power can be converted to phase power, thus the system power under non-sinusoidal and unbalanced condition is obtained. The suggested method can calculate the power of different harmonics, avoiding the unreasonable phenomena of power under different frequencies be offset, and the calculation of this method is small and the calculation accuracy is high. Finally, the method is validated by Matlab simulation.