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Instruments and equipments, especially like satellites, spacecraft and otheraerospace electronic systems, should be grounded safely during their operation.Stability and reliability of the grounding system are related to the operational statusof the entire system, and they play a vital role in ensuring the safety of equipment aswell as operators. Resistance characteristic of grid branches is the most importantperformance indicator of grounding system. However, due to the influence fromenvironment or quality defect during construction, it is very often for grid branchesto get corroded or fractured, leading to failure of grounding system, and resulting insevere potential accidents. The traditional grounding grid fault diagnosis methodslack of research on the test node optimization techniques, and the testing cost is high.Therefore, the research of test node optimization and fault diagnosis technology ofgrounding grid and developing of corresponding fault diagnosis system arespecifically needed, which can be widely used in national defense, military andeconomic areas.Firstly, this paper studies on suitable fault diagnosis algorithm for groundinggrid. Through modeling analysis of the grounding grid, the least squares parameterestimation is applied to the slip resistance diagnosis, which helps in analyzing thecredibility of the algorithm and developing the algorithm into recursive form, andmakes it more suitable for online estimation of the parameters.Secondly, the paper analyzes and studies on the testability of the groundinggrid. With the help of hierarchical reduction method, the ground network issimplified, which provides the judgment of the branch fault. On this basis, anoptimization technique based on genetic algorithm is further investigated, and thusthe optimized distribution of touchable nodes is shown.Then, the paper completes the overall design of the fault diagnosis system,which includes the host computer diagnostic software and test hardware circuits.Based on modular design concept, the host computer software, which is the centralcontrol of the entire system, achieves basic algorithm, optimization techniques,instrument driving, and human-computer interface programming. The hardwarecircuit completes the design of channel switch matrix, the conversion circuit ofcommunication interface, and the CPLD bus controller and sub controllers.Finally, the model of grounding grid is built for testing. And a fault diagnosisexperiment platform is built to test the network model, and data is collected back tothe host computer for fault diagnosis. The host computer provides diagnostic results,numerical analysis and display based on the data collected. The result of the diagnosis can be used to evaluate the performance of the system, to achieve thepurpose of fault location and judgement on branches of network by least touchablenodes,and to verify the correctness and feasibility of the test node optimization andfault diagnosis algorithm.
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