Method for calculating transient currents in short circuit of any position of rail traffic direct-current traction network
A DC traction and rail transit technology, applied in the field of rail transit, can solve problems such as difficulties in establishing calculation models and uncertain working modes of rectifier units
Active Publication Date: 2013-12-11
ZHEJIANG UNIV
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Problems solved by technology
When the near-end short circuit occurs, the current is between the two extreme conditions, which makes the working mode of the rectifier unit uncertain, which brings great difficulties to the establishment of the calculation model
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[0022] Step 1. Obtain calculation parameters. Specifically, the AC side power supply system short-circuit reactance X s , rectifier transformer full short-circuit reactance X k , the equivalent resistance of the rectifier transformer R T , rectifier transformer secondary side line voltage rating U 2 , the commutation reactance X of the 12-pulse rectifier unit c , the equivalent impedance Z of the external circuit seen from the rectifier port eql , namely R eql +jX eql . Among them, Z eql is a parameter related to the location of the fault.
[0023] Step 2. Calculate the steady-state short-circuit current calculation value I k. Specifically, the rectifier unit is equivalent to a voltage source with internal resistance by using the method commonly used at this stage, and the steady-state short-circuit current is calculated by establishing the external characteristic linearization model of the 24-pulse rectifier unit.
[0024] Step 3. Calculate the discrimination coeff...
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The invention relates to a method for calculating transient currents in a short circuit of any position of a rail traffic direct-current traction network. At present, a simple and practical calculating method does not exist for the analysis of near end faults, and the method for clearly distinguishing a near end shortcircuit, a far end shortcircuit and an outlet shortcircuit does not exist. Firstly, calculating parameters are obtained, then the calculating value of a steady-state shortcircuit current is calculated, partition coefficients are calculated according to the positions of the faults, and finally the calculation of the steady-state current is carried out by selecting an outlet shortcircuit calculation formula or a near end shortcircuit calculation formula or a far end shortcircuit calculation formula according to the partition coefficients. The method calculates the partition coefficients according to the positions of the faults, and then the steady-state current calculation method of the near end shortcircuit or the far end shortcircuit or the outlet shortcircuit is selected according to the partition coefficients. The method fills the blank that a near end shortcircuit steady-state current calculation method does not exist at present, and the fault of any position of a rail traffic direct-current system can have a practical calculation method meeting project error requirements.
Description
technical field [0001] The invention belongs to the field of rail transit, and in particular relates to a transient current calculation method for a short circuit at any position of a direct current traction network of rail transit. Background technique [0002] Accurate calculation of short-circuit current in rail transit DC traction network is not only the basis for system design and planning, but also the basis for setting and verification of relay protection values. It is of great significance to ensure personal safety and reduce failure losses. There are many operating modes of DC traction network, and the external circuit parameters and the operating state of the rectifier unit have a great influence on the short-circuit current when a fault occurs. It is required that the fault calculation method can take into account the simplicity and accuracy of engineering practice. [0003] There have been many studies on the calculation of the steady-state short-circuit current ...
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IPC IPC(8): G01R19/00
Inventor 王慧芳许成
Owner ZHEJIANG UNIV