电流限制毕业论文

Three-phase short-circuit is power system planning, design and operation of the calculation and analysis to work. At present, three-phase current short road condition has become a troubled many domestic electrical key problems. However, in the three-phase short-circuit current calculation, the design, operation and the calculation method of the research department adopts each are not identical, this may cause short-circuit current calculation results and the difference of the judgment of short-circuit current exceeds differences, and short-circuit current the short-circuit current calculation results rather conservative, may cause unnecessary waste of investment, If you tend to be optimistic, the safe and stable operation of the system of catastrophic. Buried Therefore, in the research of short-circuit current calculation standard based on the different condition of short-circuit current calculation of short-circuit current calculation results for grid, and the influence of short-circuit current calculation and limit to provide more practical methods and short-circuit current calculation methodClassic short-circuit current calculation method for: change than , do not consider lines and parallel compensation capacitor recharge, don't consider the impact load and load current node voltages, take the , generator racing. The standard of short-circuit current calculation are mainly IEC standard and the ANSI standard, China USES is the IEC standard. Owing to the short-circuit current calculation method and calculation conditions. The standard recommends three-phase short-circuit current calculation method is equivalent voltage source, its calculation method for: 1) does not consider the rotating load operation data and generator excitation way, 2 lines and ignore the rotating electrical load of parallel admittance, 3 the transformer has tap-changer and its position as the position in the Lord, Regardless of the arc resistance; (4) 5 35 kV short-circuit current calculation system, the maximum equivalent voltage source, the nominal voltage from 1 (1) in the calculation of the rated voltage of the contributions of pu), but shall not exceed the maximum operating voltage power grid planning and operation department, three-phase short-circuit the biggest is main content of calculation. The grid computing, and electricity network in different departments may use different calculation conditions. Differences are mainly concentrated in transformer, node voltage selection. Transformer has taken , have taken more than the actual operation change, Node voltage may take , also may take contributions. These two different combinations are adopted, obviously, this will affect short-circuit current calculation results. The root of the problem is calculated according to calculation program to staff the natural Settings to calculate and calculation program and lack of flexibility. Actually, if you know a short circuit calculation and the requirement of personnel is calculated from the calculation results can be appropriately. Some commercial software also provides flexible short-circuit current calculation conditions setting function. enterprise2 influence factors of short-circuit current calculation resultsAmerican PTI company PSS/E program provides short-circuit current calculation based on the trend of the classical method, and the ANSI standard or IEC standard of short-circuit current calculation. IEC standard, allows users to set arbitrary short-circuit current calculation of the initial value. Set of options include: (1) change than choice: or normal variable ratio, 2 consider whether charging capacitance, 3 and parallel compensation or not, 4 node voltage, 5 generator power factor. Therefore, using PSS/E procedures for its own example with different initial conditions of short-circuit current calculation results of analysis