The measurement of harmonics in modern electrical power systems is essential for evaluating the degree of distortion, identifying sources of disturbances and mitigating them, etc. In this context, the role of instrument transformers is crucial, as they are key elements for reporting HV voltage and current signals to each measurement instrument installed on the network. However, inductive instrument transformers, which are still the most widely used, act as filters due to their dynamic behavior and behave in a non-linear manner due to their iron core. The objective of this article is an in-depth analysis of the performance of two digital signal processing techniques, recently proposed in the literature and aimed at mitigating the effects of the non-linear behavior of instrument transformers: SINDICOMP and harmonic distortion compensation for means of polynomial modeling in the frequency domain. Their performance for the purpose of improving the measurement of voltage harmonics is analyzed by means of numerical simulations, using for this purpose waveforms that can typically be found in the grid in normal service conditions.