Design Of Intelligent Control System For Power Transformer Oil Temperature

As the power consumption of the society continues to increase,the heat dissipation problem of the power transformer poses a great challenge to the safety of the power grid.Excessive operating temperature will directly threaten the life of the internal insulating oil and insulation of the transformer,reduce the load capacity,greatly shorten the operating life of the transformer,and affect the safe operation of the transformer.Therefore,the temperature control of the transformer is particularly important.In thesis,a new type of transformer oil temperature control system is developed.The system uses programmable logic controller(PLC)as the control core to realize intelligent control of transformer oil temperature.Based on the Modbus-RTU communication protocol,PLC performs master-slave communication control on multiple cooling fan frequency converter through RS485 network,which realizes the smooth adjustment of the cooling capacity of the cooler and improves the control precision.Taking the top oil temperature and load current of the transformer as the control signal,some new transformer oil temperature control strategies are proposed,which improves the service life of the equipment,reduces the fault and ensures the stable operation of the transformer.The fuzzy control theory is used to control the cooling fan,which can realize the timely adjustment of the transformer oil temperature.While stabilizing the oil temperature of the transformer,it can reduce energy consumption and improve efficiency.The touch screen and PC software enable on-site and remote monitoring of the oil temperature control system to enhance human-computer interaction performance.The system can meet the development needs of substation and intelligent power plant,and is the development direction of transformer temperature control system in the future.The main research contents of this thesis are as follows:(1)Power transformer loss calculation and thermal analysis.Establishing a relationship model between the transformer oil temperature parameters and the parameters of the transformer cooling system to solve the corresponding loss and heat distribution.It provides a theoretical basis for the subsequent study of the control strategy and hardware and software design of the cooling control system.(2)System structure and hardware design.The structural design of the transformer oil temperature control system was completed,and the selection of the hardware equipment and circuit design were carried out.The selection of PLC and the design of its hardware circuit and the design of the communication network between PLC and frequency converter are emphasized.(3)Research on intelligent control strategies and methods.According to the loss calculation and thermal analysis results and the relevant rules of the transformer oil temperature control system,based on the control system hardware circuit,the intelligent strategy and method of the transformer oil temperature control system are studied.The focus is on the intelligent fuzzy frequency conversion control method of the cooling fan,and the design and simulation of the fuzzy controller are mainly carried out.(4)System software design.According to the research results of intelligent control strategy and method,the software design of the control system is carried out in combination with the system hardware,including the main program of the control system,the fuzzy control program of the cooling fan and the design of the communication program.Finally,the design of the monitoring interface of the upper computer is also carried out.