Research On Fault Indicator Current Detection In Distribution Network

As an indispensable part of modern industry,the importance of electric power grids in the national economy becomes more pronounced.People have put forward higher requirements for reliability of power supply.As a link connecting the transmission grid and the power users,the reliability of the distribution network’s power supply has a major impact on the safe and stable operation of the entire network.Due to the wide distribution and complex structure of the distribution network in China,line faults,especially single-phase earth faults,occur.The positioning problem has not been properly resolved.Fault indicator is an important tool for quickly locating faults in distribution lines.It has been widely used in recent years,but most existing fault indicators cannot meet the requirements of fast real-time fault identification.The transient recording type fault indicator can be smaller.Investing in the fault location function of the distribution line segment and recording the high sampling rate of the transient current is the key to achieving its fast fault location.Therefore,in this thesis,the current detection unit of the overhead transient recording wave fault indicator is the main research object.Firstly,the characteristics of the phase voltage and phase current when the 10 k V overhead distribution network fails are obtained.The criteria of the fault recording wave clearly define the current detection requirements and determine the Rogowski coil as the current detection unit.Secondly,the equivalent model of the lumped coil current sensor lumped parameter is established,and the response performance of the current sensor under different parameters to the steady load current and fault current is simulated;the fault indicator open structure is further combined,the sensor structure and parameters are optimized,and the current is developed.The prototype of the sensor analyzes the steady state and transient performance of its opening.Finally,a hardware experiment platform was built to perform steady-state performance and frequency response,and short-circuit fault current simulation tests on the current sensors.Experiments show that the Rogowski coil current sensor developed in this thesis can meet the requirements of steady-state current measurement and fault identification in transient recording wave fault indicator.