Distribution transformer monitoring and automatic load sharing

Abstract

The main electricity utility company in Uganda owns and operates over 10,000 Distribution Transformers and loses over 800 Distribution Transformers annually due to various reasons. At present, the distribution company uses a peak load analysis scheme to determine the transformer load conditions, which is a tedious task and doesn’t solve the problem of Distribution Transformer failure resulting from; load unbalance, over load among others. In this project we designed a system that monitors the voltage, current and ambient temperature of Distribution transformers and by using a standby transformer to perform automatic load sharing between the transformers when they exceed their rated value. We made a prototype that monitors important parameters of a single transformers i.e. the voltage, current and ambient temperature using voltage sensors, current transducers and temperature sensors. Readings from the sensors are processed by the microcontroller and the GSM module sends these parameters of the distribution transformer periodically to the respective service area engineers which are later relayed to the control center transformer database which contains the transformer ratings, GPS location and contact of engineer in charge. Secondly by using a standby transformer connected in parallel to the main transformer through a relay system with the main transformer supplying the loads and the other in stand-by mode, we set a reference load current value according to the transformer ratings. When the load goes beyond this value for the primary transformer, the standby transformer relay coil is powered to put the two transformers in parallel hence sharing the load equally.