Design Of High Voltage And Large Capacity Power Transmission And Transformation System And Research On On-line Monitoring Method Of Grounding Fault

The safe and stable operation of power transmission and transformation system,on the one hand,depends on the rationality of its design,the matching of design depth and operation conditions,on the other hand,depends on the scientificity of condition monitoring during operation,and the timeliness of fault monitoring and elimination.Reasonable design can make the construction process smooth and efficient,and provide great convenience for the later operation and maintenance;Scientific monitoring is an important guarantee of the operation stage,and it is an important premise to quickly eliminate the operation failure.The disconnection between design and operation will cause great hidden danger to the reliability of power system.This paper combines the design and monitoring of power transmission and transformation system,and considers the methods to improve the power supply reliability of high-voltage and large capacity power transmission and transformation system from two aspects.Firstly,a 220kV planned transmission and transformation system in Jinan is taken as the research object,and the transmission and transformation system is designed in combination with operation,environment,load and other factors.Firstly,considering the size and characteristics of current and future loads,the main electrical wiring design and main transformer selection are carried out reasonably.Secondly,the rated parameters and short-circuit withstand parameters of equipment and conductor are determined through the calculation of short-circuit current and analysis of loop working current.Finally,the load of conductor is analyzed combined with environmental conditions,and the sag of conductor is determined reasonably.Secondly,according to the different types of lines designed in the second chapter,the grounding monitoring method is studied.When the grounding fault occurs,the variation law of electrical parameters under different grounding operation modes is different,which determines that corresponding grounding fault monitoring methods should be adopted for different grounding operation modes.This paper analyzes the fault characteristics of the two lines,studies the corresponding grounding fault monitoring methods,and uses the wavelet analysis method to de noise,time calibration and polarity analysis of the observed fault signals,so as to make the monitoring results have higher accuracy.Thirdly,in order to eliminate the error of overhead line sag to the monitoring results,this paper carries on the sag correction to the monitoring results.In order to further improve the accuracy of the correction value,this paper improves the calculation method of the line length in the file.By using the expectation of conductor icing probability distribution as the calculation parameter of line load,the accuracy of the monitoring results is greatly improved,so as to further improve the monitoring accuracy.Finally,taking the equipment selection of the design system as the simulation parameters of the fourth chapter,the effect of combining the simulation verification with the actual project is realized,which further verifies the rationality of the design and the effectiveness of the grounding monitoring method.