JPS60163739A - Method of reducing insulation in at feeding type substation - Google Patents

Abstract

PURPOSE:To reduce the insulating intensity of electric installation on the feeding side in a substation by providing a neutral on a feeding side winding using a three-winding transformer and inserting a reactor between said neutral and a rail, in an AT (autotransformer) feeding type transformer for feeding. CONSTITUTION:An AT feeding type substation feeds a voltage, obtained by dividing a feeding voltage generated in its feeding transformer Tr by means of an autotransformer AT, between a trolley line T and a rail R. In this case, a three-winding transformer is used as the feeding transformer Tr, a neutral is provided on a feeding side winding, and a reactor, with which a short-circuit device (e.g., a bypass gap G) is provided in parallel, is inserted between the neutral and the rail R. Thereby, an electri-car current, which flows into the neutral of the transformer Tr is restrained, while the insulating intensity of a feeding side electric installation in the substation is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to reducing the insulation of a feeding substation that simply supplies current in an AT feeding system AC electric railway.

FIG. 1 shows the configuration of a single-phase feeding circuit in a conventional AT feeding system.

In the conventional AT station system, the feeding voltage at the substation is twice the voltage used by the electric car, and the voltage divided by the autotransformer MuT is supplied to the electric car between the ttFav line T and the rail R. So, the normal ground voltage of the feeder line is equal to the electric car voltage, and the insulation strength is 1! ``fiL voltage is half.

However, in substations, the cage side of the heavy duty transformer is non-grounded, so if ATf is not connected before power supply starts, a ground fault may occur on the cage side of the substation. , the ground potential of the ground fault phase becomes 0 potential, and the potential of the healthy phase is 1! Rise to the level of a king.

For this reason, the insulation strength of the cage side of the substation is required to be one times the voltage of the electric car.

In contrast, the present invention relates to an AT feeding system using a three-winding transformer, in which secondary and tertiary windings with equal 'fILFE are connected in series and a neutral point is provided on the cage side. .

In other words, by installing a short-circuit device in parallel or inserting an actor between the neutral point of the transformer and the rail, electric vehicle current is suppressed from flowing into the neutral point of the transformer, and the AT is connected. By reducing the insulation strength of the cage side of the substation to half of the conventional one, taking into consideration the possibility of a ground fault in the event of a ground fault, an economical and highly reliable @electric system is provided.

The present invention will be explained below with reference to the drawings. In addition, in the turtle circuit, the resistance component is very small compared to the actance component, so in the following explanation, the resistance component will be ignored and only the reactance component will be considered.

Figure 2 is an equivalent circuit showing the separation reactance of a three-winding transformer.

Generally, the leakage reactance of a transformer with a large number of windings is 2
One of the windings j of the set is short-circuited, a voltage is applied to the other 1, and the voltage and current are measured when the other windings are opened, and the value converted to the reference voltage is displayed as xlj.

Now, if we measure xlj for the three-winding transformer with the second gate's turns ratio /@/:/ and add the separation reactance of each winding, we get
As is well known, .

By the way, when using it as an AT voltage, the secondary winding and tertiary winding are connected in series and the neutral point terminal is taken out, so It is easy to understand that it is separated into an equivalent circuit with actances XT s XN, Xp expressed as 7.

Since the winding ratio of each winding is /:/:/, it becomes.

Next, if Al is not connected, the T-phase or ! The voltage and current distribution when a phase is grounded is
Let's consider the simplest single-phase transformer with a neutral point.

In Fig. 1, when the T-N terminals are short-circuited and voltage v0 is applied to the -V terminals, the left and right windings are in series for the negative winding, so winding 1. The same current flows through /' and creates a magnetic field. For the left core leg, current flows through the winding - to cancel out the magnetic field, but in the right core leg, the magnetic field is not canceled because winding 3 is open, and the current flowing to the next winding becomes extremely small. 〇As a result, the voltage of the secondary winding becomes approximately θ, and the full voltage is applied to the tertiary winding, increasing the voltage from the normal vo to 2V.

rise to In other words, since the potential to the ground at the neutral point is θ, the potential of the healthy phase will rise to about twice the electric car voltage. It turns out that it cannot be reduced.

Therefore, we will consider the same thing regarding the hair pressure device with a separate iron core leg shape and the winding arrangement shown in Fig. S. In this case, for the second winding, the upper and lower windings are in parallel, and independent currents flow through the windings / and /' to generate a magnetic field. For the upper core leg, the windings are short-circuited, so a current flows and cancels the magnetic field, and a large current flows in the winding 4%.@For the lower core leg, the magnetic field is not canceled because winding 11jJ is open. , only a small excitation current flows through the winding l'.

As a result, the voltage of the tertiary winding is the same V as before the short circuit.

Therefore, the potential of the healthy phase does not rise.

In this way, a three-winding transformer is a transformer in which the windings are arranged so as to always produce a canceling magnetic field with respect to the negative winding, and the voltage of the healthy phase does not increase even if the negative phase is short-circuited. The problem of potential rise is solved by using this transformer.

If the voltage and current capacity of the secondary winding of the three-winding transformer used as the AT voltage are made equal, and the arrangement of the secondary and tertiary windings with respect to the -order winding is approximately equal, the three-winding transformer's The actance is , and the actance separated into the cage side is as follows from equation (3), X0+x, 1, Xp + X@, ,
−・−・−−−−・−・−(t).

By the way, when looking at the current distribution when AT is connected to a three-winding transformer, in the equivalent circuit of diagram vg6, Vu '-VAT '' XT IT - JXATIF
+XNI, VO-Vat” -Xll x@ +koX
AT IF 10”G )F ・vmv-a-・-(4)
Since L - engineering τ 0 engineering F, engineering, - engineering τ - engineering F, the voltage is erased and the load becomes a constant current source.

The glue actance of formula (R) is XN 40 from formula (S), which is practically 41XAT and X-10XF, so
At the neutral point, I,, −+−Xmu ・・・・・・・・・−・・・・・・・
It can be seen that a current of about (f) flows and the utilization ratio of the transformer's width to capacity becomes extremely poor.

In Fig. 9, insert the turtle flow suppression glue handle at the neutral point and 1f
- indicates an example of the present invention.

Figure 2 is an equivalent circuit of Figure 1 with the current suppression reactor actance as No. 1. ! The current distribution on the side becomes (by replacing x and l in the η equation with X1+ + X4.

In this case, the unbalance rate of the current in the cage side winding of the transformer is defined as: For example, if ttE is 417 kV, a single-phase transformer with t OMVA and % reactance of 6% is used, and the AT glue actance is 14-㎜ and SΩ, change the value of α and find the value of α. If you look at it as shown in Figure 9, by inserting 0, that is,
It is possible to improve the utilization rate for the line capacity key of the F device.

If you insert a current suppression reactor at the neutral point of the transformer,
As explained above, the unbalance of the current on the transformer side can be suppressed.
If a ground fault occurs on the side of the power station m when G' is open, a larger voltage will be generated at both ends of the reactor than in normal times.
to prevent a sudden discharge due to the ground sheath and a significant voltage rise across both ends of the reactor.

Note that it is also possible to provide a bypass switch that is linked to the Scower 1 in parallel with the reactor.

As explained above, according to the present invention, the m current flowing to the neutral point of the transformer for @4 is suppressed, and the FIL of the electric question on the side of the transformer ph is reduced compared to the conventional AT type blade type. By reducing the amount of electricity by half, it is possible to provide an economical and highly reliable power feeding system.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of the conventional ATlk relaxation system, Figure 1 is an equivalent circuit diagram showing the separation reactance of a three-winding transformer, and Figure 3 is ? ! An equivalent circuit diagram of a three-winding transformer showing the separation reactance on the power side, Figure 4 is a winding arrangement diagram when a neutral point is provided in a heavy-phase transformer, and Figure S is a separate heart-lung type three @ Line ratio transformer winding arrangement v1! , Figure 6 shows 4f+! using a three-winding transformer. @
An equivalent circuit diagram of an AT power type with reduced strength, and Fig. 9 is a circuit diagram of an embodiment of an AT power type in which the neutral point current of the present invention is suppressed, changes are made, and the insulation strength of the electrical system is reduced. , FIG. S is an equivalent diagram of FIG. 7, and FIG. 9 is a diagram showing the relationship between the actance of the 'am suppressing reactor and the unbalance rate of the current in the transformer room side winding. Ty...Satonta transformer, A'l", AT, and ATt
・・・Autotransformer, /, /', ko and 3...Transformer winding, VO...power supply voltage ratio, -□...voltage applied to AT,! , , X, and χ, and the separation reactance of the military transformer, X(
... Reactor glue actance for suppressing perfusion, XAT
・-Autotransformer glue actance '1. ”% work and IN
... Window transformer @ current on power side, IC = load current,
α... Current unbalance rate of transformer cage side winding 1, S
Koto... Heavy duty breaker, G... Shuttle gap, sI
I+...discharger, U, v...transformer-next winding terminal, T...trolley wire, 1...feeder, N-...neutral point of transformer, R... Designated Rail Agent Kuchimoto National Railway President's Office Legal Affairs Division Manager Sumire 1 Figure 2 Figure 3 Figure 4 Section 5 Leaf 6 Figure 2F Figure 7 Figure 8, X & [Ω] Toki Figure 9

Claims (1)

[Claims] In a heavy-duty transformer in the autotransformer @ electric system (hereinafter referred to as the AT stationary system), a three-winding transformer is used to provide a neutral point on the feeding side winding, a short circuit device in parallel, or an acdle. By inserting it between the neutral point and the rail, it suppresses the electric car current flowing into the neutral point of the transformer, and
A method for reducing insulation in an AT power type substation, characterized by reducing the insulation strength of the wide side electrical equipment in the substation.