A Low Cost Device for the Compensation of Voltage Transformers

In the paper a low cost method for the compensation of Voltage Transformers (VTs) is proposed. The compensation technique is based on a proper circuit connected to the secondary terminals that, by sensing the VT primary current, generates a voltage that compensates the primary voltage drops. The designed circuit for the compensation is physically separated from the VT, so that it proves to be easily employed for enhancing the performance of commercial VT or VT already working on the transmission network. For the measurement of VT primary current, a proper transducer has been designed; it allows the measurement of low current (in the range of milliampere) granting the required insulation between the primary circuit and the measurement section. In order to configure the compensating circuit, the VT primary parameters have to be known; a suitable method, thus, for the characterization of VT, is also proposed.