A Comprehensive Literature Review of Compensation Techniques for Current and Voltage Instrument Transformers: Enhancing Measurement Accuracy at Fundamental and Harmonic Frequencies

The integration of distributed energy resources and power electronic devices in modern power systems has led to significant power quality challenges, particularly the increasing of harmonic components in current and voltage waveforms. Accurate measurement of both fundamental and harmonic components is essential for grid stability, reliability, and efficient operation. Conventional inductive current and voltage transformers, while widely used, suffer from nonlinearities such as hysteresis and saturation, which degrade measurement accuracy, especially at harmonic frequencies. This paper presents a comprehensive literature review of compensation techniques aimed at improving the metrological performance of instrument transformers. It evaluates methods including Polynomial Harmonic Distortion compensation (PHD), SINusoidal characterization for DIstortion COMPensation (SINDICOMP and Extended SINDICOMP), Volterra INtegral Compensation for Instrument TrAnsformers (VINCITA), Artificial Neural Networks methods (ANN), tensor linearization, hardware-based solutions, and temperature compensation. Each technique is analysed in terms of computational complexity, real-time capability, model dependency, need for prior characterization, and scalability. The review highlights the trade-offs between model-free flexibility and model-based precision, offering insights into the selection of appropriate compensation strategies for enhancing harmonic measurement accuracy in modern power systems.