The Design Of An Intelligent Transformer Terminal Unit

The power distribution transformers are widely used in transformation of the energy to users. Transformers are both the terminal of the distribution network and the front-end of the user. The working state of the distribution transformer influences the quality of power supply to users. Most transformers are installed outdoor, their safety can't be guaranteed because they work continuously unattended.Transformer Terminal Unit (TTU) is a terminal device installed next to distribution transformers. TTU monitors transformers' operating conditions, detects abnormal problems and deals with these problems Timely. TTU collects transformers' operating parameters and user consumption information, providing the data infrastructure for the optimal operation of distribution network. TTU realizes low-voltage reactive power compensation to improve the quality of power supply.Based on the analysis of the current situation of power distribution system, and the needs of distribution automation in our country, a new design of intelligent transformer terminal unit is proposed in this paper. This design hires a high performance ARM Cortex-M3 microprocessor as the control unit, and a high-precision three-phase energy metering chip ATT7022C as the data processing unit.A capacitor switching algorithm is designed to compensate the power grid with reactive power, so as to enhance the power factor of the distribution network, and eventually to improve the quality of power supply.Finally, a compound switch is developed adopting a parallel structure of thyristor and magnetic latching relay.