The Development Of Supervisory Control System For Transformer's Economical Operation

With the further development of electrical industry, energy conservation and consumption reduction, the significance of economical operation of transformers become more and more outstanding. However, in the current power system, most of transformers are still in the state of natural operation with electrical consumption rate of approximately 10% of the total power production and 50% of the power loss respectively. Thus the study on transformer economical operations is vitally significant. This thesis studies the development of transformer economical operation of HOkV power substation in the suburb of Kaifeng city, China.The economical operation of transformer refers to the full exploitation of the equipment and machineries available to maximally lower the power consumption of transformers with the reasonable selection of transforming modes, the perfect modulation of the load curve, the optimal combination of current transformer position, and the improvement of the current operation conditions on the basis of secure transformer operation and sufficient power supply.It expostulates the current situation and significance of national energy exploitation and the significance of transformer economical operation, and then reexamines its history and technological situation, finally it put forward the functions of the control system required by the real-time operation of 1 lOkV power substation in Kaifeng, China. Furthermore, it expounds the fundamental principles of transformer economical operation, the calculation of active power loss-saving, reactive power loss-saving and comprehensive power loss-saving together with the characteristics of load-consumption. It mainly focuses on the criteria of economical operation of two-winding transformer in power substation under transformer operating combination and separation, and finally, it proposes its calculation modes for comprehensive power conservation.The objective of this thesis is to develop the control system for transformer economical operation for 110kV power substation in Kaifeng. This system will be installed with the hardware of "EVOC" series and its necessary accessories of PCL-813, PCL-720 intelligence I/O board manufactured by Yanxiang Engineering &Manipulation Group and intelligent electric quantity transducer. So far, the preliminary selection and design of peripheral circuit elements has been accomplished. The system input are tensimulative quantities (active power, reactive power of two main transformers and etc) and seven switching quantities (the junction signal of breakers on both side of the transformer),while the output data comprises 14 switching quantities.This control system is developed with the software of Access Database, C++ Builder as well as Yanxiang dynamic linked library PCLS-DLL1, PCLS-DLL2 on the windows platform. The software aims to monitor the real-time transformer operation and make timely control decision based on the economical operation criteria and constraints on transformer operation, then construct the real-time manipulative strategies. The software functions as follows: (1) store the simulative and switching data into real-time database for information share and enhancement of real-time system control. (2) monitor the transformer operation with operation cues or real-time control in accordance with the real-time transformer load fluctuation, the two modes are to the options of the operator. (3) demonstrate the operation and condition with data, graphs etc, which can be typed and stored. (4) enjoy the function of event database which can record the operation of both the transformers and the operators for further inspection. The control software has friendly interface and feasible operation to the user's convenience.A simulated test is performed in the laboratory as the preparation for control system and experiment. The system consists of industrial personal computer, intelligent I/O board, direct current source, simulative input circuit, switching input circuit and switching output circuit. The simulated test illustr...