Design And Implement Of Calculation Software For Distribution Line Protection’s Fixed Value

Relay protection equipment is an important part of the power system to ensure the safe operation of the power system,and it is also a vital part of the power system security system.In order to ensure that the protection equipment can quickly and accurately judge and make a correct response when a grid fault occurs,it is necessary to carry out accurate calculation of protection settings.This can ensure that the reliability,sensitivity,selectivity and response speed of the protection equipment meet the requirements.This paper combines the development experience of relay protection setting software at home and abroad,and according to the customization needs of Coslight Electric Enterprises,it conducts in-depth research on the analysis of short-circuit faults in the operation of the distribution network,the process of setting value setting,and the graphic display of fault recording data.,developed a set of graphical relay protection setting calculation software,which is used to set the distribution line of a petrochemical refinery in Tianjin.Due to the high price of the general-purpose setting calculation platform on the market,and the need to build the line and enter the line parameter information when using it,the operation is relatively cumbersome.For this reason,the interface and functions of the fixed value setting calculation software developed in this paper are only designed for the needs of the enterprise,which greatly reduces the use cost of the enterprise and improves the operation efficiency of the setting personnel.This relay protection setting calculation software system is developed on the Mac OS system by using the QT development platform and C++ language development tools.In this paper,the software is carefully designed,and the overall function is divided into several modules,including short-circuit current calculation,fixed value setting calculation and data management,etc.,and a graphic display interface for wave recording data is also designed.In each chapter,the design ideas and design process of each module are introduced in detail.And this paper provides detailed setting rules for the setting calculation of power grid relay protection equipment,aiming to meet the requirements of reliability,sensitivity,selectivity and rapidity of protection equipment.In order to facilitate the user to choose the setting value according to his own experience,this paper provides two setting methods: automatic setting and manual setting.Users can choose the appropriate setting method according to their own needs,so as to perform fast and accurate protection setting calculation.The software realizes that when the setter wants to perform the setting calculation operation,he can perform the short-circuit calculation operation first,and then complete the setting calculation.The calculation results are stored in word documents and databases,realizing the calculation from the short-circuit current to the fixed value setting.continuous operation.The time domain and frequency domain information on the fault recording data can also be viewed conveniently and quickly through the software,which is helpful for the setting personnel to adjust the setting value setting results in time.Finally,this paper also conducts a verification test on the functional application of the software.This software is mainly aimed at the tuning software for distribution lines of a petrochemical refinery in Tianjin.After combining the specific line parameter information of a petrochemical refinery in Tianjin given by the company,the software output is verified by using the tuning process of one of the lines as a practical example.the accuracy of the results.The software will present the calculation results of the short-circuit current and the setting results of all lines to the user in the form of a notice.Then test the graphic display of the fault recording data.After selecting a recording data file,randomly select a group of data,open the recording data file with this software,and find that group of data.After comparison,the two are the same.The last is the test of the fixed value verification part.The protection logic of the over-current section 1,over-current section 2 and over-current section 3 has been tested,and the test results are the same as expected.