Fault Analysis And Detection For The High Voltage Electric Power Metering System

The measurement of the electric power system with high voltage and strong capacity plays an important role in the course of electric system generation, transmission and supply. The fault of measurement system, whether it is caused by nature or by human beings, can lead to the wrong measurement of the electric power which is used by users.Consequently, it is necessary to explore some methods by which the fault of the electric power measurement system can be diagnosed correctly. Among these methods is the detection technology of the the short circuit fault of the current transformer (including the short circuit of primary/secondary side, short circuit of secondary side of current transformers) and opposing connection of transformer and one or two of the three-phase voltage disconnection which are one of the hot research topics in the electric power measurement system.Based on such a reason, the detection technology of the the short circuit fault of the current transformer is taken as the main research content which is explained in details as follows:(1) A network fault model for the high voltage electric power metering system is proposed in this paper. Firstly, the closed relations between short circuit of the primary or secondary side of current transformer and the network impedance are drawn from the circuit parameter analysis of the metering system under the different loads. Secondly, an auxiliary circuit is designed, used to detect the impedance changes from which the fault model is derived. Finally, Simulations are performed on the model to demonstrate the efficiency of the fault detection model.(2) It is analyzed that one or two of the three-phase voltage disconnection and some means of detecting fault. Meanwhile, it is also analyzed that the fault of short circuit of secondary side of current transformers and opposing connection of current transformer. We can judge not only faults but also the types of the faults by use of the phase relationship of two-phase current. The detection circuit is simple, realized easily; furthermore, only two voltage values need to be measured.