Study On Application Of Short-Circuit Current In Engineering Design Of Power Supply And Distribution Of Building

Short-circuit fault is a huge threat in the building power supply and distribution system,which brings great harm and seriously affects the system's safe and stable operation.Therefore,it is necessary to carry out scientific short-circuit current calculation,and using the computing result to check the wire and equipment and to tune the relay protection device in the power supply and distribution system,so that them can meet the requirements of electrical technical indicators of the installation.It can be seen that study on application of short-circuit current in engineering design of power supply and distribution of building has a very large practical significance and practical value.Through access to a large number of related papers,reading the relevant norms,and analyzing,comprehending,researching all of its contents,this article is finally accomplished.And the key points of this paper are as follows:1.Carding the basic theory of short-circuit.Firstly,comprehensively introducing the causes of short-circuit faults,the types of short-circuit,the serious consequences of short circuit and the measures to prevent short circuit,and discussing the probability of each type of short circuit occurs and how to eliminate the root causes of faults;Then,emphatically analyzing the physical process of the infinite high capacity power system,emphatically studying the meaning of related short-circuit current value and the the relationship between each other,and presenting important role of some important physical quantities in the practical engineering,providing a set of short-circuit current related theory,which lays a solid theoretical foundation for the following research.2.Calculating and analyzing high and low voltage network.Firstly,analyzing two methods of short-circuit current calculation in the power supply and distribution of building in detail: the ohm method and the per unit value method,and summing up the commonly used range and application comparison according to the characteristics of the two methods;Secondly,describing the calculation process of low voltage network and the influence of large capacity the feedback current of the large capacity motor on the system,which establishes a comprehensive theoretical system for short-circuit current calculation;Then,introducing the force effect and thermal effect caused by the short-circuit current,and bringing out the check formula of the dynamic stability and thermal stability in all cases.3.Studying the application of short circuit current in the engineering design of power supply and distribution of building,which is the core of the research.Firstly,analyzing thefunction of the short-circuit current in the application of the project,and giving the precondition of the short circuit current checking and short circuit current tuning;Then,checking dynamic stability and thermal stability of bus and cable,checking dynamic stability,thermal stability and arcing ability of electrical equipment,tuning relay protection action value and sensitivity of protection device,and listing the theoretical formulas of check and tuning and the meaning of each symbol in the formula.4.Analyzing the actual engineering case,which is research results of the paper.Firs of all,analyzing the power supply scheme of the project case,and selecting the system operation mode and the short circuit point;Secondly,calculating the short-circuit current value of the short-circuit point according to the calculation method of the second chapter;Then checking the main wire and the electrical equipment in the power supply scheme according to the check formula given in the third chapter;Finally,getting the check results to determine whether the electrical design of the project meet the requirements of electrical technical indicators.Through the research of this paper,giving the projections and formulas of the short-circuit current check of the wire and electrical equipment and of the short-circuit current tuning of the relay protection device in the power supply and distribution system,which provides the theoretical basis for the actual engineering electrical design and ensures the security and stability of power system.