Numerous critical applications for managing the electrical grid require measuring voltage and current signals. Traditionally, this is done using Voltage Transformers (VT) and Current Transformers (CT), often inductive, which are robust, reliable, and, importantly, stable and less sensitive to influencing factors when measuring sinusoidal signals at the network frequency. However, these devices have, alongside their undeniable advantages, some drawbacks, particularly related to the imperfections of the ferromagnetic core. The simultaneous development of smart grids is leading to a rapid transformation of current station and substation infrastructures through the digitalization of key measurements, creating what are known as Digital Substations (DS). These DS incorporate new, innovative measurement tools called smart meters. One of the primary electronic devices installed in these new substations is the Stand-Alone Merging Unit (SAMU), used for digitalizing measurements. However, the imperfections of the transducers affect the measurements from smart meters, and often, the errors from the transducers are such that the uncertainties associated with the measurements exceed permissible limits.

Under certain conditions, the sum of errors introduced by the measurement chain, including the transducer and smart meter, can cause exceedances of the limits set by current Power Quality regulations. To address the issue of transducer imperfections, specifically measurement transformers, it was proposed to study models for compensating these imperfections and to integrate these models into the compensatory functionalities of smart meters.

RSE’s activities have focused on designing a high-accuracy three-phase SAMU prototype, equipped with advanced features capable of executing compensation models for measurement transformers developed by leading Italian universities working on these topics. The collaboration with Italian universities has led to the integration of compensation models within the S-SAMU3, achieving excellent results in terms of improving the accuracy of VT measurements.