RU2710957C1 - Adjustable symmetrical installation of alternating current traction substation - Google Patents

Abstract

FIELD: electrical engineering.SUBSTANCE: invention relates to the field of electrical engineering, in particular to adjustable filtering compensating installations of traction power supply system. Disclosed is an adjustable symmetrical installation of AC traction substation, comprising a first adjustable single-phase filter compensating unit connected in parallel to traction winding of step-down transformer, supplying arm with "lagging" phasevoltage, current and voltage measuring transformers installed in each phase of transformer traction winding and on each arm of contact network power supply respectively, which secondary windings are connected to intelligent terminal, which performs the function of measuring electrical parameters of contact network. At that, it is equipped with the second adjustable single-phase filtering compensating unit with two poles, the first and second 27.5 kV switching switches with the input and output each and the design unit including two comparison circuits, two INHIBIT elements, NOR element and three actuators, wherein two first switching terminals are connected to first adjustable plant second terminal, outputs of which are connected to phasesandtraction winding of transformer, respectively, second pole is connected to phasetraction winding. Intelligent terminal is connected to the input of the first and second comparison circuits, the output of one of which is connected to the non-inverting input of the first INHIBIT element, inverse input of which is connected to the second comparison circuit, inverting input of the second INHIBIT element, non-inverse input of which is connected to the second comparison circuit and the first input of the NOR element, second input of which is connected to the second comparison circuit, and outputs of the first and second INHIBIT elements and NOR elements are connected to inputs of the first, second and third actuators, respectively.EFFECT: technical result consists in improvement of reduction efficiency of currents and voltages unbalance caused by single-phase traction load of variable nature.1 cl, 1 dwg

Description

"The technical field to which the invention relates"

The invention relates to devices for power supply of railway transport, and in particular, to balancing units made on the basis of adjustable single-phase transverse capacitive compensation units in traction AC networks of 25 and 2 × 25 kV systems.

"Prior art"

The problem of voltage asymmetry caused by single-phase traction loads is known, for example, from [1].

For AC traction substations of 25 and 2 × 25 kV with “lagging”, “leading” and “free” phases of the voltage of the traction winding of a step-down transformer to reduce current asymmetry in [2, Fig. 9a] it is indicated that when the ratio of the currents of the supply arms n is within 0.7–1.5, it is sufficient to include a single-phase adjustable installation of transverse capacitive compensation in the “lagging” voltage phase, which can reduce the asymmetry of currents by 1.7–2 times. To translate the installation [2, Fig. 9a] in the regulated mode, it is possible to use circuits according to Fig [2, Fig. 12]. Currently, on domestic railways To compensate for reactive power in a traction network, the following adjustable single-phase filter-compensating installations (FCUs) [3] are included: a switchable filter-compensating installation and a static reactive power compensator, which, in accordance with [2], can be used to form a balancing installation.

We accept [2, Fig. 9, a] - for the prototype of the invention. Thus, we consider an adjustable balancing installation of an alternating current traction substation, comprising a first adjustable single-phase filter compensating installation connected in parallel with the traction winding of a step-down transformer, supplying a shoulder with a “lagging” phase of voltage ca, measuring current and voltage transformers installed in each phase of the transformer winding and in each arm of the power supply of the contact network, respectively, the secondary windings of which are connected to the intelligent terminal, in suppl function of measuring the electrical parameters of the catenary.

The disadvantage of the prototype is the insufficient reduction of asymmetry with a significant difference in the currents of the arms of the power.

In [2, Fig. 30] it is indicated that the asymmetry is reduced to almost zero at any ratios of the currents of the arms of the supply by phase-controlled KUs only if "... one KU is constantly connected to the lagging phase, and the other switches depending on the ratio of currents to the leading or free phases," that is, as shown in [2, Fig. 9, b, c]. However, in the technical literature there is no data on a specific circuit design and technology for effectively reducing asymmetry at a traction substation.

"Disclosure of inventions"

The objective of the invention is to propose a specific circuit solution for the effective reduction of voltage unbalance at an AC traction substation.

To achieve this goal, an adjustable balancing installation of an alternating current traction substation is proposed, comprising a first adjustable single-phase filter compensating installation connected in parallel with the traction winding of a step-down transformer, supplying a shoulder with a "lagging" phase of voltage ca, measuring current and voltage transformers installed in each phase of the transformer traction winding and on each arm of the power supply of the contact network, respectively, whose secondary windings are connected to an intelligent rminalu performing the function of measuring the electrical parameters of the catenary. At the same time, it is equipped with a second adjustable single-phase filter-compensating installation with two poles, the first and second switching switches 27.5 kV with input and output each and a calculation unit including two comparison circuits, two BAN elements, an OR-NOT element and three actuating elements, while the inputs of two switching switches are connected to the first pole of the second adjustable installation, the outputs of which are connected to phases a and from the traction winding of the transformer, respectively, the second pole is connected to phase b of the traction oh winding, and the smart terminal is connected to the input of the first and second comparison circuits, the output of one of which is connected to the non-inverse input of the first BAN, the inverse input of which is connected to the second comparison circuit, the inverse input of the second element BAN, the non-inverse input of which is connected to the second comparison circuit and the first input of the OR-NOT element, the second input of which is connected to the second comparison circuit, and the outputs of the first and second BAN element and the OR-NOT element are connected to the inputs of the first, second, and third ny element, respectively.

So, the novelty of the invention is as follows:

- the adjustable balancing installation of the traction substation of alternating current includes two FCUs, while the first FCU in the supply arm with the "lagging" phase of the voltage is non-switchable, and the second FCU can switch from the "leading" to the "free" phase of the voltage and vice versa;

- introduced the function of measuring the current and its phase to determine the moment of switching the second PCF between the phases of the voltage of the transformer, performed in an intelligent terminal;

- introduced switching switches in the switching circuit of the second PKU;

- The switching algorithm of the second PKU has been refined.

"Brief Description of the Drawings"

The scheme of the invention is presented in the drawing.

"Implementation of the invention"

The following notation is introduced in the drawing.

1 - traction winding of a step-down transformer with a voltage of 27.5 kV with “lagging” (phase bc), “leading” (phase ca) and “free” (phase ab) voltage phases;

2 - measuring current transformer installed in the phase of the traction winding of the transformer;

3 - voltage measuring transformer installed in the supply arm of the contact network;

4 - the first adjustable single-phase filter-compensating installation;

5 - the second adjustable single-phase filter compensating installation;

6 - the first switching switch 27.5 kV with a drive;

7 - second switching switch 27.5 kV with a drive;

8 - intelligent terminal;

9 - calculation unit;

10 and 11 - the first and second comparison schemes, respectively;

12 and 13 - the first and second logic elements are FORBIDDEN respectively;

14 - logical element OR-NOT;

15, 16 and 17 - the first, second and third actuators, respectively;

18 - connection of the supply lines of the contact network;

19 - rails.

The proposed installation works as follows.

At a traction AC substation, filter-compensating units 4 and 5 are connected to the winding of a step-down three-phase transformer 1 with measuring current transformers 2 in each phase, and installation 5 is connected through switching switches 6 and 7. Depending on the ratio of currents in the supply arms with installed measuring voltage transformers 3 PKU 5 switches to the "leading" or "free" phase voltage.

In accordance with [2], in order to reduce the asymmetry of currents and voltages to zero, it is necessary to perform calculations of the ratio of currents of the supply arms for each instantaneous value of the load current:

and then compare with the following calculated p value:

where I _opt and I _Ot are the instantaneous values of currents in the power arms with the “leading” and “lagging” voltage phases, respectively;

ϕ _opt and ϕ from _t are the instantaneous phase values of these currents.

To calculate the phase characteristics of the currents of the supply arms with “leading” and “lagging” voltage phases, an intelligent terminal 8 with the function of measuring the electrical parameters of the contact network is introduced into the invention.

We determine the conditions for connecting the PKU 5 to the “leading” or “free” phases of the transformer voltage (in the presence of the calculated coefficients α and δ)

- if the condition is met

n> α⋅р,

then PKU 5 should be connected to the “leading” phase cb of the voltage of the traction winding of the transformer by turning on the first switching switch 6, (switching switch 7 is off).

- if the condition is met:

n <δ⋅р,

then PKU 5 should be connected to the “free” phase ab of the traction winding voltage of the transformer by turning on the second switching switch 7 (switching switch 6 is off).

- if the condition is met:

δ⋅р≤n≤α⋅r,

then you should turn off both switching switches 6 and 7 (PKU 4 in the power arm with the "lagging" phase of the voltage remains on).

According to the operating experience, it is advisable to take in (3) - (5) the following calculated coefficients: α from 1.1 to 1, and δ from 0.8 to 0.9.

Calculations according to expressions (1) - (5) are performed in calculation block 9.

As a result, the operation algorithm of the proposed balancing installation of traction substation of alternating current will be as follows.

In the initial state, the load currents along the supply arms, measured by the intelligent terminal 8, have values that do not satisfy the conditions (3) and (4) for the corresponding comparison circuit 10 or 11 of the calculation unit 9 to operate, and the switching switches 6 and 7 are turned off.

When condition (3) is determined by the comparison circuit 10, a logic unit signal appears at its output, which is fed to the input of the first element BAN 12. If there is no signal at the output of the comparison circuit 11 (logical signal zero is present), then element 12 opens and its output appears a signal of a logical unit, which comes to the actuating element 15 and makes the switch 6.

Similarly, the fulfillment of condition (4) will ensure that at the input of the second element PROHIBIT 13 the logical unit signal from the output of the comparison circuit 11. At a logical zero at the output of the comparison circuit 10, the element 13 is opened and the logical unit signal is output from the output element 17. In this case, switch 7 is turned on.

When condition (5) is fulfilled, or, otherwise, conditions (3) and (4) are not met, comparison circuits 10 and 11 are in an unworked state, which ensures the presence of a logical signal zero at their output, and this, in turn, is the appearance of a signal logical unit at the output of the element OR NOT 14, which passes to the actuating element 16 and makes the circuit breakers 6 and 7.

For traction power supply of 2 × 25 kV AC, all of the above remains true. Despite the fact that, as a rule, in a 2 × 25 kV system, transformers are single-phase, but the effect of lagging and leading phases is the same. Therefore, switching the PKU in phases remains the same. It should be noted that the balancing at traction substations of a 2 × 25 kV system using a phase-switched single-phase PKU in this invention is indicated for the first time.

The technical and economic effect of the invention consists in improving the quality of electricity at a traction substation by balancing currents and voltages.

Literature

1. Tamazov A.I. The asymmetry of currents and voltages caused by single-phase traction loads. M .: Transport, 1965.235 s.

2. Borodulin B.M., German L.A., Nikolaev G.A. Condenser installations of electrified railways. M .: Transport. 1983, 183 p.

3. German L.A., Serebryakov A.S., Dulepov D.E. Filter-compensating installations in railway power supply systems. Knyaginino: NNIEU, 2017, 402 p.

Claims (1)

Adjustable balancing installation of traction substation of alternating current, containing the first adjustable single-phase filter compensating installation connected in parallel to the traction winding of a step-down transformer, supplying a shoulder with a "lagging" phase of voltage ca , measuring current and voltage transformers installed in each phase of the traction winding of the transformer and on each supply arm contact network, respectively, whose secondary windings are connected to an intelligent terminal that performs the measurement function electrical parameters of the contact network, characterized in that it is equipped with a second adjustable single-phase filter compensating installation with two poles, the first and second switching switches 27.5 kV with input and output each and a calculating unit that includes two comparison circuits, two elements BAN, element OR- NOT and three actuators, while the inputs of two switching switches, the outputs of which are connected to the phases a and from the transformer winding, are connected to the first pole of the second adjustable installation ora, respectively, the second pole is connected to the phase b of the traction winding, and the smart terminal is connected to the input of the first and second comparison circuits, the output of one of which is connected to the non-inverse input of the first COMPLETE element, the inverse input of which is connected to the second comparison circuit, the inverse input of the second COMPLETE element , the non-inverse input of which is connected to the second comparison circuit and the first input of the OR-NOT element, the second input of which is connected to the second comparison circuit, and the outputs of the first and second BAN elements and the OR-NOT connected to the inputs of the first, second and third actuators, respectively.

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