| Due to the multifold advantages as improving reliability, neutral small current earth represents a typical scheme in MV and LV power distribution networks. But because the phase to earth fault current is tiny whereas the interference is relatively heavy, fault line detection has become a troublesome problem, which hasn't been settled satisfactorily for long time.This thesis sets out from ameliorating debugging and testing methods of the fault line detection equipments to devote to solving the problem mentioned above. The principal contents are as follows:The principium and characteristic of neutral small current earthed power system normal running state and single-phase-to-earth fault running state are presented in this thesis, elements that influence fault line detection are educed, and the main difficulties of fault line detection are concluded. This thesis takes the aim reflecting these elements and difficulties truly as the essential desire of the fault line detection equipments debugging and testing systems.A method is proposed to solve fault line detection equipments debugging and testing problems to establish small current fault line detection physical simulative experimental system. Aiming at the actuality that neutral small current earthed fault line detection problems are poorly solved, this thesis comes from the methods of fault line detection equipment debugging and testing, analyzes the principium, features and deficiency, combines with the fault line detection points, proposed the scheme of establishing the neutral small current earthed fault line detection physical simulative experimental system.The main body of the thesis describes the structure, features and effects of the simulative experimental system. It also introduces an assisted scheme of developing a simulating test equipment.The skeleton of the experimental system is the model of a 10kV electrical grid, including all the correlative experimental equipments, such as protection, measuring and analyzing equipments and so on. Further, it also involves the single-phrase-to-ground fault simulation and the experimental system security regulations. The voltage, current, impedance and time of the experimental system have all achieved 1:1 simulation to the actual power system. Fault reproduction is achieved as veridical as possible.A contrast is made between the fault data from experimental system and a certain power station. The sufficiency and verity of the experimental system simulation areproved. The experimental system accords with the need of fault line detection equipments debugging and testing. Data also reveal the obvious deficiency of other methods.The experimental system is not only the foundation to understand the 10kV grids running properties and fault essences, but also the base and tools of theory exploitation and technology improvement. Every achievement in our research team comes from the experimental system, including the clarification of acquaintance, the realization of estimate for several fault line detection theories and exploitation of efficiency range, as well as the invention of new theories and equipments.An idea of develop a simulating test equipment is shaped and comes to scheme. It can move easily and repeat debugging and testing at will. It has a longer life and less maintenance work. It is an essential assist for the experimental system.The scheme of the equipment: Take advantage of mathematics modeling to analyze and manage physical model, fault data of experiment system or field, then establish a computer model, and form a program. Fault mode is chosen through dialogue with the computer. Fault voltage and current are calculated automatically and transmitted to single-chip controller. Signal transformed and disposed in the single-chip controller that is homologous to the power system can be received.The physical simulative experimental system creates groundwork for neutral small current earthed fault line detection equipments research and development, and reveals the reason...
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