The widespread use of power converters in low-voltage distribution grids has given rise to issues regarding the power quality. In fact, non-linear loads such as AC Drives, switching-mode power supplies and grid-connected converters can cause, besides the generation of several current harmonics, also a DC current component injection into the grid. This DC current component can lead to magnetic saturation of the distribution power transformers; in this condition, the transformers present distorted current waveforms, increased power absorption and overheating, that can damage the transformer insulations. This paper presents a way to diagnose the magnetic saturation by a non-direct measurement of the DC current component flowing in the power transformer. In other words, the proposed solution provides an information about the total DC injection produced by the sum of all the electric devices connected to the distribution power transformer. The DC current component causes a DC voltage drop across the parasitic resistance of the transformer's winding: sensing this DC voltage drop allows to evaluate the DC current component. A magnetic sensor was developed in order to obtain a great sensitivity, and the implemented closed loop control allowed to guarantee a good linearity with a high rejection ratio of the grid voltage variations. Simulation and experimental results confirm the effectiveness of the proposed approach.
A Sensor to Detect the DC Bias of Distribution Power Transformers / G., Buticchi; Lorenzani, Emilio. - ELETTRONICO. - (2011), pp. 63-70. (Intervento presentato al convegno 8th IEEE Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives, SDEMPED 2011 tenutosi a Bologna, ita nel 5-8 September 2011) [10.1109/DEMPED.2011.6063603].
A Sensor to Detect the DC Bias of Distribution Power Transformers
LORENZANI, EMILIO
2011
Abstract
The widespread use of power converters in low-voltage distribution grids has given rise to issues regarding the power quality. In fact, non-linear loads such as AC Drives, switching-mode power supplies and grid-connected converters can cause, besides the generation of several current harmonics, also a DC current component injection into the grid. This DC current component can lead to magnetic saturation of the distribution power transformers; in this condition, the transformers present distorted current waveforms, increased power absorption and overheating, that can damage the transformer insulations. This paper presents a way to diagnose the magnetic saturation by a non-direct measurement of the DC current component flowing in the power transformer. In other words, the proposed solution provides an information about the total DC injection produced by the sum of all the electric devices connected to the distribution power transformer. The DC current component causes a DC voltage drop across the parasitic resistance of the transformer's winding: sensing this DC voltage drop allows to evaluate the DC current component. A magnetic sensor was developed in order to obtain a great sensitivity, and the implemented closed loop control allowed to guarantee a good linearity with a high rejection ratio of the grid voltage variations. Simulation and experimental results confirm the effectiveness of the proposed approach.Pubblicazioni consigliate
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris