Study On Fault-indicating System Based On Multiple Feature Fusion For Dry-type Transformer For Coal Mine

The project in this thesis is one important part of the project "Safety Status Monitoring and Fault Diagnosis Forecast of Mine Ventilation Power Supply System" (No:2007BAK29B05), sponsored by the National Key Technology R&D Program of China during the Eleventh Five-year Plan Period..The work is proposed in accordance with the lack of accurate fault diagnosis equipment for mining flameproof dry-type transformer and its failure to find electrical fault in the wind or happened in advance.With the continuous development of coal mining technology of large mining height fully mechanized working face,the total installed power of coal cutter and scraper conveyor in working face has increased rapidly,and the capacity of dry-type transformer for coal mine has exceeded more than 5000 kVA.A mobile transformer substation of flame-proof type with 10 kV large capacity for coal mine has been developed in civil on their own,its capacity is as much as 6300 kVA.As the core of power supply system of coal mine, the overall performance and the stand or fall of running state of dry-type transformer for mining directly affects the reliability, security and continuity of power supply of coal mine.The method of monitoring dry-type transformer mainly rely on thermocouple installed inside of the transformer’s body to detect internal temperature, then it control relay to protect dry-type transformer from high temperature.But this method only can monitor a single parameter,it can not effectively reflect the real-time state of dry-type transformer insulation,neither can not effectively predict the fault before the accident and avoid the happening of mining accidents.Therefore, research on fault diagnosis system for mining dry-type transformer of flame-proof type has an important economic and practical significance.Combining with the corresponding test model,the paper did a deep research on system of condition monitoring and fault diagnosis for mining dry-type transformer of flame-proof type,and it achieved good results.Main research contents are as follows:After site investigation,domestic and abroad literature reviewing, maintenance experience learning, it summarizes the common failures of dry-type transformer type and analysis fault mechanism,then it determines the data parameters that can reflect running state and fault types of dry type transformer.The data parameters mainly includes the three-phase voltage and current of high voltage side,three-phase winding temperature, the temperature of three-phase high voltage contactor,the temperature of three-phase low voltage contactor and core, leakage current of core and partial discharge of three-phase high voltage winding etc.Based on the characteristics of each parameter, the corresponding monitoring method was put forward.Using the chip TMS320F2812 as the CPU, it designs a hardware circuit for the supervising system on dry-type transformer. It is compose of several circuits for signal modulation data collection, signal synchronization, communication and so on. Experiment demonstrate the accuracy of the hardware circuit. On the base of the hardware circuit, we adopt a program design method of modulation to write out a software for the supervising system on dry-type transformer that includes a data collection program for the parameters, a calculation program for characteristic variables, communication program and so on. After debugging, the module function can be achieved.Basing on the data collection of the transformer, we study the fault analysis method for the dry-type transformer, which includes the establishment of the fault tree of the dry-type transformer and the expert system, application of fuzzy theory and so on. By setting up the model between the turns and layers of the winding and with the help of infrared thermography, we study the insulator model between the turns and layers to know the influence the partial charge has on the winding temperature. Through the analogy of charge patterns and the character curve of the temperature increasing in different aging temperature, we get the relationship between the partial charge between the turns and layers respectively and the temperature on the condition of using NOMEX painted paper as insulator layer for the dry-type transformer.By applying the heat transmission theory and calculating and analyzing the numerical character of the NOMEX painted paper insulator for dry-type transformer used in the mine, we know the influence the partial charge between the turns has on the winding heating procedure within the dry-type transformer used in the mine, then we establishment a database of fault information.By integrating the fault information within the system, it can perform the field fixing and debugging. The result show that the system is safe and stable, and has accurate data collection and good real-time quality and reliable communication. It can meet the demand for the design. At the same time, it certifies the correctness and feasibility of the design scheme.