Computation of average values of synchronously sampled signals

The problems of numerical computation of the average value of regularly and synchronously sampled periodic signals to resolve issues raised elsewhere are addressed. The undersampling methods are analysed, and it is shown that the formula for computation of the average value based on the trapezoidal numerical integration method provides correct results for all harmonic components of the sampled signal except those whose whole number of periods fit the sampling time step. The influence of subharmonics and interharmonics is analysed, and it is shown that the undersampling methods suffer from errors that might be caused by their presence. Application of the method to electric power measurement when the voltage spectrum and the current spectrum have different band limits is discussed, and conditions that guarantee correct results are derived. An example that illustrates the application of these techniques is presented.