With the economic development, the high quality has become a critical issue for service continuous of power companies. To ensure the stable power supply, the asset management of power equipments is applied to prevent the system outage. With voluminous distribution transformers over very wide area, the real time monitoring of temperature has been included in the scope of smart grid. During recent years, the service outage due to transformer overloading has caused customer panic as well as deterioration of service quality. This thesis develops the Transformer Terminal Unit (TTU) by integration of computer chip for power consumption, DSP and sampling circuit of temperature measurement to achieve the functions of real time monitoring of transformer operation condition. When an abnormal operation condition such as overloading or high oil temperature occurs, the TTU can report the contingency back to the control station via the hybrid communication system so that the distribution system operators can take remedy action to prevent the contingency. The actual loading and temperature of transforms are also measured and collected in this study to develop the relationship of temperature and loading levels. By collecting transformer temperature, the power demand of a transformer can be estimated and the load shedding can then be activated to prevent the problem of overloading when the temperature exceeds the operation constraint.

In this dissertation, the transformer management system has been developed to monitor transformer over loading and generate warning message in conduit mapping management system (CMMS) of Taipower company. The transformer over loading prediction is performed by both offline and online modes. Performs the transformer loading estimation by using the customer monthly energy consumption in customer information system (CIS) and the connectivity attributes of transformer and customers served in CMMS system of Taipower company. The daily load curve of distribution transformer is derived considering the typical daily load patterns which have been developed in load survey study. The warning message will be generated when the peak loading estimated is lager then the transformer rated capacity. To enhance the accuracy of transformer attributes in CMMS system, the transformer phasing measurement system (TPMS) and the connectivity identification system to identify all of the customers served by each transformer are developed. It is difficult to receive the 1 pulse per second signal form global positioning system for timing synchronization of TPMS measuring units for phasing measurement of transformers located in basement, the temperature compensated crystal oscillation with Fuzzy calibration algorithm is used to maintain the timing synchronization within 10o deviation for measurement period of 2 hours. To solve the incorrect problem of transformer and customer connectivity in CMMS, the power line carrier technology is applied in the design of connectivity measurement system for the identification of customers served by the transformer. The peak loading of transformer is estimated by including the temperature effect and the overloading flag of transformer is displayed on the CMMS automatic mapping system. For the online TLM system, the embedded transformer terminal unit is developed for the real time measurement of transformer loading and insulation oil temperature. For the transformer with abnormal operation condition, the alarm signals will be generated and transmitted to the TLM master station via hybrid communication system for the activation of demand response function to execute the load shedding control of customer loads.