Research On Simulation And Analysis Platform For Smasll Current Grounding Fault Based On PSCAD Software

Small current grounding line is the distribution network relay protection long-term concern of the hot and difficult.With the continuous expansion of the size of the grid and the gradual increase in voltage levels,the distribution of the capacitor current to further increase the non-fault phase of the insulation put forward higher requirements.So timely and accurate selection of fault lines for the safe operation of the distribution network is of great significance.It is helpful to improve the efficiency of research and to facilitate the design of test results.It provides a more standardized simulation analysis platform for studying small current grounding line selection.Therefore,based on the electromagnetic transient simulation software PSCAD / EMTDC and the control circuit,a set of simulation platform with low reliability,high flexibility and easy operation is proposed,and the accuracy of the selection line is analyzed.Sex.This article has done the following work:1.Analysis of single-phase ground fault characteristics of small current grounding system.Firstly,the transient process and steady-state process of single-phase earth fault are analyzed in detail.The characteristics of single-phase earth fault of small current system are summarized,which lays the theoretical foundation for fault line selection of small current grounding system.Secondly,the theoretical analysis Fault current signal size,unbalanced current interference,intermittent arc on the accuracy of small current grounding line selection.Finally,according to the above analysis to determine the distribution network fault line selection platform of the basic theoretical method.2.Based on electromagnetic transient simulation software PSCAD / EMTDC to build a small current ground fault simulation analysis platform.The simulation platform to 110 /10 kV system,for example,the use of single-piece segment of the wiring,the transformer for the Y-? wiring,can achieve three overhead lines and three cable lines split operation.Respectively,the transformer module,overhead line module,cable module,ground variable module,circuit breaker module,fault module parameter settings.As the transformer triangle side can not lead to the neutral point,where the grounding through the realization of the neutral point by the arc suppression coil grounding.The platform has to change the voltage level,the system wiring,system parameters,neutral grounding and the realization of custom functions.According to the new line selection method can be a new custom components to facilitate the future expansion of the platform.3.The simulation platform uses the zero sequence current ratio amplitude method,the zero sequence fundamental wave ratio ratio method and the polarity comparison lineselection method,respectively,from the amplitude,phase,polarity three aspects of the design of the control circuit criteria,And the various control modules for packaging modeling.The amplitude module and the phase module each contain two control circuits,the polarity module contains a control circuit.Each control circuit module carries on the line selection experiment separately,realizes the automatic judgment the magnitude magnitude,the phase direction and the polarity positive and negative function,the failure line automatically outputs the high level,the non fault line output low level.4.The results of the line selection of each operation circuit module are simulated and analyzed in the arc-suppression coil grounding system at the neutral point ungrounded system and the neutral point respectively.For the cable and the overhead line,Ground angle and transition resistance of the three aspects of simulation analysis;amplitude selection and phase selection line steady-state simulation analysis,the polarity of the line for steady-state and transient simulation analysis,from multiple angles Verify the correctness of the platform selection.The establishment of the platform for small current grounding line selection of more targeted for engineering practice and application provides a valid data.It is important to judge the pre-judgment and pretreatment before the fault and observe the operation result of the grid change parameter.