Research And Design Of Intelligent Cooling Control System For Main Transformer Of A 500 KV Substation In Shijiazhuang City

With the development of ultra-high voltage power grid,a 500 kV substation in Shijiazhuang as an important part of the North China Power Grid,carrying Hebei,Beijing and other places important power transmission and transformation tasks,the reliability of main transformer has become very important for the safety of the power grid.But its main transformer cooling control system still uses relay logic control mode,which has many disadvantages such as complex control loop,high failure rate,difficult maintenance,low reliability and large control error,which seriously threatens the reliability of power supply.With the gradual promotion of unattended substation management mode,in view of the many defects of the relay control mode,combined with the relevant regulations and on-site operation and maintenance personnel,this paper puts forward the intelligent cooling control system,which uses the PLC as the center controller,the transformer top oil temperature as the controlled amount,non-contact AC solid state relay instead of AC contactor as the implementation of components,the transformer cooling device as the controlled object.The system consists of dual power automatic transfer switch,motor protector,switch knob device,oil surface thermometer and on-site cooling control cabinet components.The dual power automatic transfer switch can ensure the reliability of the two power supply.The motor protector can protect the fan and the oil cooler motor from short circuit,overload and overpressure.In addition to the design of the hardware part described above,this subject has done a lot of research on the software part of the cooling control system.Combined with PLC under the machine software programming design,proposed a comprehensive intelligent cooling system control strategies such as differential margin cooler switching control,according to the running time polling switch cooler control,work cooler fault automatic control,cooler full stop control Wait.In addition,combined with the environmental impact of high-frequency electromagnetic interference in the substation,PLC under the machine and the host computer use optical fiber for long-distance communication.And the host computer LABVIEW software programming cooling control system is used to remote communicate and monitor.The new system can greatly overcome the shortcomings of the original relay cooling control system.It is easy to expand,functional,reliable operation,easy maintenance and so on.As the ideal alternative of the traditional transformerair-cooled control system,the new system achieve intelligent control of the cooling system.