Method for balancing load of traction transformer

FIELD: power engineering.

SUBSTANCE: method allows to fully utilize power of traction transformer due to loading its free phase by rectifiers and inverters, one of which is lead by leading phase of contact network, and second one of late phase, which allows to transfer electric energy to contact network, to exclude idling mode, to provide for lower asymmetry on reverse series in power grid 220 (110) kV, and also decreases level of higher harmonics.

EFFECT: higher efficiency, lowered values of quality coefficients of electric energy - asymmetry coefficient of reverse series and values of higher harmonics.

2 dwg

 

The invention relates to electric power and is intended for use on traction substations AC electrified Railways.

Known way to turn the traction transformers lies in their connection to the phase line 220 (110) kV transposed by the scheme (see Kguard. The supply of electrified Railways. M.: Transport, 1982, p.36-38).

Closest to the claimed method is the inclusion of traction transformers, which consists in distributing the load of the contact system in two phases transformer, connected respectively to advanced and lagging phases of the network (see ibid., pp.24-25).

The main disadvantage of this method is inefficient use of power traction transformer for traction load, as one phase of the transformer on the side of the average load of 27.5 kV is unloaded, i.e. it can be used only 66.6% of the power transformer. If the traction substation is located in a sparsely populated area, consumption by 10 (6) kV slightly, then single phase traction transformer operates in the idle mode, consuming only the magnetizing component current, which causes significant higher harmonics in the supply network, as well as the growth coefficient values ASI is metry in a reverse sequence.

The technical result of the proposed method is to increase the efficiency of the traction power transformer, as well as the decrease in the values of indicators of quality of electric energy asymmetry factor in a reverse sequence and values of higher harmonics.

The result is achieved by a method for balancing load of the traction transformer, which consists in distributing the load of the contact system in two phases of the transformer, the load distributing advanced to third, the unloaded phase of the transformer, the voltage taken from this phase, rectify and convert using two inverters, led respectively advanced and lagging phase circuit, a sinusoidal voltage with a frequency equal to the frequency of the main harmonic of the network, and through single-phase transformers serving a specified voltage in the corresponding phase of the contact network.

The inventive method eliminates the major disadvantages inherent in the known method, which is associated with loading the unloaded phase traction transformer rectifier and inverters, one of which is advanced by the phase of the contact network and the second backward, which allows to transmit electric power in a contact network with the appropriate choice of the capacity of single-phase transformers, vypra is Italia and inverters, almost equal to the rated capacity of the previously unloaded phase, and thereby to eliminate the idle mode, which will reduce the asymmetry in a reverse sequence in the supply network 220 (110 kV), and will also reduce the level of higher harmonics. The latter is due to the fact that they will straighten up, and their energy will be using inverters to be submitted in a contact network in the form of energy the main harmonics and used for traction.

Figure 1 is a diagram of one device that implements this method, figure 2 - diagram of the simulation method.

Figure 1: 1 and 2, respectively forward and backward phase circuit, 3 - rail cloth, 4 - average load winding of the traction transformer, 5 - unloaded phase traction transformer, 6 - single-phase transformer, 7 - rectifier, 8 - inverter driven anticipatory phase, 9 - inverter driven backward phase, 10 a single - phase transformer advance phase, 11 - single-phase transformer lagging phase.

The method is as follows.

When you enable traction transformer 4 to the rectifier 7 through single-phase transformer 6 is supplied with alternating voltage taken from the unloaded phase 5. The rectified voltage from the output of the rectifier 7 is fed to the inputs of the inverters 8 and 9, the slave respectively advanced and lagging phases contact the hildren, AC voltage of the main frequency from the outputs of the inverters 8 and 9 by means of single-phase transformers 10 and 11 served in the contact network.

This method allows to download traction on all three phases of the traction transformer and reduce the values of quality indicators power factor reverse sequence KU2and values of higher harmonics, since the higher harmonic voltage phase 5 of the traction transformer straightened and returned in the contact network in the form of electrical energy of the fundamental wave of the network.

The modeling method was carried out according to the scheme of figure 2, where 12 is a three-phase transformer 13 is loaded phase secondary winding 14 is unloaded phase of the secondary winding 15 key 16 - rectifier, 17, 18 nonlinear variable load, 19, 20 inverters, led by the network, 21, 22 single - phase transformers, 23 - analyzer power consumption AR.5, 24 - scheme simulating the external power supply scheme.

Simulation of the proposed method gave the following results: when the key 15 a load of the transformer can be increased by 35% from the start, while the coefficient U2declined from 5.26 to 1.14 (when load growth 35%), tgϕ fell from 0,84 to 0.17, the distortion factor of the waveform of the voltage from 6.8 to 1.96.

Thus, the proposed CSP is about allows more efficient use of the capacity of the traction transformer for traction, and also reduce the quality of electrical energy, namely the asymmetry factor in a reverse sequence and values of higher harmonics voltage.

The method of balancing the load of the traction transformer, which consists in distributing the load of the contact system in two phases of the transformer, wherein the load distributing advanced to third, unloaded, phase transformer, the voltage taken from this phase, rectify and convert using two inverters, led respectively advanced and lagging phases of the contact network in a sinusoidal voltage with a frequency equal to the frequency of the main harmonic of the network, and through single-phase transformers serving a specified voltage in the corresponding phase of the contact network.



 

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