Research On Intelligent DC Power Supply System Used In Transformer Substations

Present situation and development of high frequency switching power supply (HF SPS) are analyzed in this dissertation domestically and overseas. The basic principle of HF SPS and its application in electric power system are studied. Then a kind of HF SPS applied in electric power system is designed in order to replace the traditional phase control power supply. The Buck full-bridge converter is made up of four MOSFET, and the theory of PWM is used. The signal of PWM is offered by current-mode controller UC3825. The primary circuit and the control circuit are insulated by transformer or photo coupler. The Soft-Start and the Over Current Self-protection are also designed. The experimental results show that the system can work safely and reliably.HF SPS exceptions, such as over-voltage, over-current, over-temperature, etc, are dealt with by carefully designed protection circuits. These circuits provide various functions to protect the system, including soft start,: drive signals mask, etc. So the reliability of the system is much more better.Each switching power supply implements load current sharing by the current sharing controlled chip which can be parallelized easily, thus capacity-expansion is very convenient.The intellectual monitor which supervises the state of switching power supply at real time is designed in the dissertation. The intellectual monitor can judge, deal with the problem in effect and transfers the information to the upper computer via the communication network.Because of the high frequency operation, this switching mode power supply has many advantages: light weight, small physical size, high reliability, etc.The experiments prove that this system has achieved the requirements which can work safely and reliably.