RU2842829C1 - Bench of external power supply system for calculations of ac traction network with two-way power supply - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to electric power supply system of traction network, and namely to development of bench of external power supply system for calculation of alternating-current traction network with double-sided power supply. Essence of the proposed solution consists in the fact that three equivalent triangles of resistances of the external power supply system are introduced into the test bench, two resistance beams of each triangle are connected to inputs of traction substations, and the third beam connects inputs of adjacent traction substations. Calculations of traction power supply are performed with due allowance for electrical connection of feed lines of traction substations of the investigated substation and adjacent inter-substation zones of traction network.

EFFECT: improving calculation accuracy of traction power supply system, and namely relay protection, since equivalent circuits of EPS are specified.

1 cl, 1 dwg

Description

Field of technology to which the invention relates

The invention relates to a traction network power supply system, namely to the development of a stand for an external power supply system for calculating an alternating current traction network with two-way power supply.

State of the art

The schemes of external power supply systems of traction networks are defined by the normative document [1]. The methods of calculating the inter-substation zones (ISZ) of the traction power supply system (TPS) taking into account the external power supply scheme (EPS) and taking into account the traction load of adjacent inter-substation zones are given in [2]. However, in [3] and [4] the erroneousness of using the EPS equivalent scheme was shown when the electrical connection of the supply networks of adjacent traction substations is not taken into account, i.e. when calculating short-circuit currents in the traction power supply system, the 110 (220) kV line ("jumper") connecting the inputs of transformers of adjacent substations is not taken into account. In [5], when considering two traction substations supplying a given inter-substation zone, the equivalent scheme of the external power supply network was adjusted in order to take into account the electrical connection of the supply lines of the traction substations. In [5] and [6] it is proposed to represent the equivalent circuit of the traction power supply system in the form of the so-called equivalent resistance triangle, the resistance rays of which, connected to the inputs of the traction substations, are connected by a "jumper" between the specified inputs of the traction substations. In [6] a stand for calculating one inter-substation zone is proposed for the implementation of the equivalent circuit of the traction power supply system and the rules for calculating the triangle rays are given. However, the existing methods for calculating the loads of adjacent inter-substation zones are still carried out without the specified equivalent resistance triangle, and therefore the calculations of traction power supply should be modernized in terms of correcting the external power supply circuit. The practice of calculating the traction power supply system shows that when determining small short-circuit currents and increased values of voltage losses at traction substations, taking into account the loads of adjacent inter-substation zones is of significant importance, which is not always done at present [7], [8].

We take as a prototype the invention [6]: A stand of the external power supply system for calculating the traction network of alternating current with two-way power supply from three-phase traction substations TP1 and TP2, where the external power supply system (EPS) is represented by the first equivalent triangle T1 of resistances ZT1 ₀₁ , ZT1 ₀₂ , ZT1 ₁₂ , which are calculated according to the short-circuit resistances at the inputs of 110 (220) kV TP1 and TP2 specified by the Regional Dispatch Control of the Power System (RDC), and in which the first ZT1 ₀₁ and second ZT1 ₀₂ beams of resistances of the power transmission lines connecting TP1 and TP2 connect the first 1 output of the power source S with TP1 and TP2, respectively, and the third resistance ZT1 ₁₂ - "jumper" connects the three-phase inputs of 110 (220) kV transformers of these substations and is calculated according to the actual parameters lines, where the parameters of the rays ZT1 ₀₁ , ZT1 ₀₂ are determined by a system of two equations with the short-circuit resistances at the inputs TP1 and TP2 specified by the control unit, and according to the obtained ZT1 ₀₁ , ZT1 ₀₂ together with the resistance ZT1 ₁₂ of the equivalent resistance triangle T1, the resistances Z1, Z2, Z3 (and the reactive resistances X1, X2, X3) are calculated when transforming the resistance triangle T1 circuit from a triangle to a star, while in accordance with the recommendations, the active component of the resistance in 110 (220) kV networks is not taken into account and instead of the complex resistance Z, the reactive resistance X is taken into account in the calculations.

In the prototype scheme (where only two traction substations TP1 and TP2 are considered), the calculations of the inter-substation zone TP1-TP2 are performed taking into account the introduced equivalent triangle T1. However, when calculating the current I ₁ of the adjacent inter-substation zone, its equivalent resistance triangle is still absent in the prototype. This is a shortcoming of the prototype, as was indicated.

The textbook [2] does not require the presence of an equivalent triangle and provides a calculation of voltage losses along the power supply arms taking into account the load of the adjacent substation zone, but without performing an equivalent resistance triangle in the SVE.

Disclosure of invention

The purpose of the invention: improvement of the equivalent circuit with the formation of a stand of the SVE traction power supply system for calculations of all operating modes, including calculations of the load of the adjacent inter-substation zone and voltage losses from them, taking into account the electrical connection of the supply lines of the SVE traction substations. To achieve the goal:

- the third TP3 and fourth TP4 traction substations are introduced into the stand, connected to the external power supply system respectively through the introduced beams of resistance of power transmission lines ZT2 ₀₂ and ZT3 ₀₁ to TP3 and TP4 and the resistance of "jumpers" ZT2 ₁₂ and ZT3 ₁₂ respectively between the inputs of transformers TP3 with TP1 and TP2 with TP4 and as a result three equivalent triangles of resistance of the SVE T1, T2, T3 are obtained, to which the traction substations TP1, TP2, TP3 and TP4 are connected, while the three inter-substation zones of the single-phase traction network have different power phases,

- the resistances ZT2 ₀₂ in T2 and ZT3 ₀₁ in T3 are determined in systems of two equations with the short-circuit resistances specified from the RDU, respectively, at the inputs TP3 and TP1 (when calculating ZT2 ₀₂ ) and at the inputs TP2 and TP4 (when calculating ZT3 ₀₁ ) and, by analogy with the calculations of the equivalent triangle of resistances T1, the parameters X1, X2, X3 of the transformed star are determined from the equivalent triangles T2 and T3 by their resistances,

- when calculating T2 in a system of two equations with short-circuit resistances specified from the RDU, the value of ZT1 ₀₁ is determined again, which may differ slightly when calculating T1, then the average value of ZT1 ₀₁ is finally accepted based on the calculations of T1 and T2, similarly for ZT1 ₀₂ when calculating T3 and T1,

- as a result, based on the obtained values of the power system resistances, the resistances of the traction substations are determined - when powered from T1

- when powered by T2

- when powered by T3

- based on the resistances of traction substations, we will determine the voltages of their supply arms, while the voltage loss of the supply arm from “its” load is determined by the product of this load and the resistance of the traction substation, however, when calculating the voltage losses from the load of adjacent substation zones, the leading or lagging phases should be taken into account, in particular, for the inter-substation zone TP1-TP2 (Fig. 1), “its” loads I _A and I _B , and currents I ₁ and I ₂ are formed from adjacent inter-substation zones,

- if the power supply arm of the inter-substation zone under consideration is connected to the leading phase, then the voltage of this arm, according to known calculations, is equal to

- if the power supply arm of the inter-substation zone under consideration is connected to the lagging phase, then the voltage of this arm is equal to

where U12 is the voltage of the power supply arm determined taking into account the voltage losses from the load of only “its own” considered inter-substation zone TP1-TP2 (I _A , I _B ).

Thus, for the correct consideration of the equivalent circuit of the traction power supply system and the formation of the stand in the calculations of traction power supply systems, it is necessary, firstly, to introduce into the stand circuit not only the first equivalent triangle of resistance for feeding one specified inter-substation zone, as indicated in the prototype, but to add two more equivalent triangles for feeding adjacent inter-substation zones, which allows taking into account the electrical connection of the supply lines of each two adjacent traction substations feeding the inter-substation zones, and at the same time, secondly, to perform calculations on the stand taking into account the traction load of adjacent inter-substation zones when all three equivalent triangles of resistance of the traction power supply system and all traction substations are included. The above represents the novelty of the invention.

The technical result of the invention is determined by refining the equivalent circuit of the SVE and, accordingly, the stand of the external power supply system, which increases the accuracy of calculations of the traction power supply system, in particular, relay protection.

Brief description of the drawing and designations

To explain the operation of the invention, we present a diagram of the stand (Fig. 1), in which the following designations are introduced.

S - power supply of the power system with terminals 1 and 2;

TP1, TP2, TP3, TP4 - traction substations;

ZT1, ZT2 resistances of transformers TP1 and TP2;

T1, T2, T3 - formed triangles of resistance of the power supply system when supplying inter-substation zones between traction substations TP1 and TP2, TP1 and TP3, TP2 and TP4, respectively;

ZT1 ₀₁ , ZT1 ₀₂ , ZT1 ₁₂ - resistances T1;

ZT2 ₀₂ , ZT1 ₀₁ , ZT2 ₁₂ - resistances T2;

ZT3 ₀₁ , ZT1 ₀₂ , ZT3 ₁₂ - resistances T3;

Z1(X1), Z2(X2), Z3(X3) - resistances of the rays of the star, transformed from the triangle of resistances T1, T2 and T3;

Z _TC13 , Z _TC24 - resistances of inter-substation zones TP1-TP3 and TP2-TP4;

Z' _TS12 and Z'' _TS12 - resistances of the inter-substation zone TP1-TP2 to the short circuit location;

I _A and I _B are the short-circuit currents of the damaged zone from TP1 and TP2, respectively;

I ₁ and I ₂ are the load currents, respectively, from TP1 and TP2 of adjacent undamaged zones;

K3 - short circuit in zone TP1-TP20 when connecting the contact network and rails.

As can be seen, the resistance rays ZT1 ₀₁ and 0 ZT1 ₀₂ of the equivalent resistance triangle T1 are common for the equivalent resistance triangles T2 (ZT1 ₀₁ ) and T3 (ZT1 ₀₂ ). The obtained resistances X1, X2, X3 in T1, T2 and T3 determine the resistances of the elements of the traction network of the connection of the power source S of the energy system with the traction substations. The traction network is represented by the distributed electric rolling stock (DRS) in the inter-substation zones TP3-TP1 and TP2-TP4 and the short-circuit device (SCD) in the zone TP1-TP2.

Implementation of the invention

Using the given diagram, we will analyze the operation of the considered equivalent circuit of the traction power supply stand. It turns out that the use of the first equivalent triangle T1 according to the invention [6] does not ensure the correct calculation of the traction power supply system taking into account the load of the adjacent inter-substation zone. To take into account the load of adjacent zones of the traction network, it is necessary to introduce the second T2 and third T3 triangles of traction power supply resistances. The resistances of the rays ZT1 ₀₁ , ZT1 ₀₂ of triangle T1, as well as ZT1 ₀₁ , ZT2 ₀₂ of triangle T2 and ZT3 ₀₁ , ZT1 ₀₂ of triangle T3 are determined based on the short-circuit resistance data at the transformer inputs from the power system RDU for each pair of adjacent substations (TP1-TP2, TP1-TP3 and TP2-TP4) based on the developments in [5] with the reduction of the traction power supply resistance when feeding traction substations from triangle schemes [5, 6]. Further, the resistances X1, X2, X3 when transforming the triangle circuits T1, T2 and T3 into a star are obtained using known formulas and are shown in [5, 6].

To calculate the resistances of traction substations when feeding each inter-substation zone from equivalent resistance triangles T1, T2, T3 of the traction power supply, expressions (1), (2) and (3) are presented.

Thus, in any traction power supply section diagram, three series-connected inter-substation zones with four traction substations and three equivalent triangles of supply resistance of the specified inter-substation zones should be identified, and then the calculation of currents and voltages should be performed in the usual way [2].

In [10], a comparative calculation of voltage losses is given without taking into account the load of the adjacent inter-substation zone; in this case, voltage losses on the traction transformer buses on the power supply arm of the inter-substation zone under consideration are reduced by 24-45%, which confirms the effectiveness of the calculations on the bench.

The technical and economic effect is manifested in the improvement of calculations of the traction power supply system with several inter-substation zones with the clarification of the external power supply network stand scheme, taking into account the electrical connection of the 110 (220) kV traction substation feeder lines in the calculations of voltage losses from loads, including from adjacent inter-substation zones. The above is necessary first of all in the calculations of the traction power supply relay protection.

Sequence of calculations on the stand:

1) calculations are performed according to the stand diagram (Fig. 1), the currents of the ERS in the traction network of all inter-substation zones are arranged, and the short-circuit points in the traction network are indicated, the capacities of the traction transformers, their short-circuit resistances, the RDU data on the short-circuit power at the inputs of 110 (220) kV transformers, the actual data on the resistances of the “jumpers” connecting the inputs of 110 (220) kV transformers of adjacent inter-substation zones are indicated,

2) a set of portable voltmeters, ammeters and phase meters is added to the stand for the corresponding measurements at any point in the traction network,

3) a calculation is performed on a stand with the equivalent triangles T1, T2, T3, traction substations TP1, TP2, TP3, TP4 and all inter-substation zones included; voltages and currents, as well as their phase angles on the traction substation buses and on the current collectors of the electric rolling stock (EPS), are determined using voltmeters and ammeters on the stand (not shown in Fig. 1),

4) if necessary, to evaluate the effectiveness of the results, the calculation is repeated separately for each inter-substation zone with the connection of only one corresponding equivalent resistance triangle and only two traction substations. A separate calculation will show how effective the calculation is on a stand that takes into account the loads of adjacent inter-substation zones of the traction network.

The invention considered four traction substations. When increasing them, the number of introduced equivalent resistance triangles should be increased.

The technical result of the invention is determined by refining the equivalent circuit of the SVE and, accordingly, the stand of the external power supply system, which increases the accuracy of calculations of the traction power supply system, in particular, relay protection.

Literature

1. SP 224. Traction power supply.

2. Marquardt K.G. Power supply of electrified railways. Moscow: Transport, 1982 - 528 p.

3. German L.A., Subkhanverdiev K.S. Estimation of the error in calculating short-circuit currents in an alternating current traction network. Electronics and electrical equipment of transport, 2017, No. 1, pp. 5-10.

4. German L.A., Subkhanverdiev K.S., German V.L. Automation of power supply of the traction network. Part 1. Moscow: State Educational Institution of the University of Management, 2022, 230 p.

5. German L.A., Karpov I.P. A refined method for calculating short-circuit currents in an AC traction network. Intelligent Electrical Engineering, 2021, No. 2.

6. Patent No. 2796196 dated 11/16/2022. Test bench for determining short-circuit currents of the inter-substation zone of the traction network (German L.A., Subkhanverdiev K.S., Karpov I.P.), Published 15/17/2023. Bulletin No. 14.

7. Figurnov E.P. Relay protection. Part 2. Moscow: State Educational Institution "UMC", 2009.

8. Collection of STO RZD. Protection of railway power supply systems from short circuits and overloads. Part 1-5. Moscow: OOO "Center for Innovation and Development" Tekhinform ", 2019, 304 p.

9. Guidelines for relay protection, issue 11. Moscow: Energia, 1979.

10. German L.A., Karpov I.P. Equivalence scheme of the external and traction power supply system in traction network calculations. Electricity, 2024, No. 5.

Claims (16)

The external power supply system test bench for calculating the AC traction network with two-way power supply from three-phase traction substations TP1 and TP2, where the external power supply system (EPS) is represented by the first equivalent triangle of resistances T1 ZT1 ₀₁ , ZT1 ₀₂ , ZT1 ₁₂ , which are calculated based on the short-circuit resistances at the 110 (220) kV inputs of TP1 and TP2 specified by the Regional Dispatch Control of the Power System (RDC), and in which the first ZT1 ₀₁ and second ZT ₀₂ beams of resistances of the power transmission lines for connecting TP1 and TP2 connect the first (1) terminal of the power source S with TP1 and TP2, respectively, and the third resistance ZT1 ₁₂ , "jumper", connects the three-phase 110 kV inputs of the transformers of these substations and is calculated based on the actual parameters of the line, with the parameters of the beams ZT1 ₀₁ , ZT1 ₀₂ are determined by a system of two equations with the short-circuit resistances at the inputs of TP1 and TP2 specified by the RDU, and according to the obtained ZT1 ₀₁ , ZT ₀₂ together with the resistance ZT1 ₁₂ of the equivalent resistance triangle T1, the resistances Z1, Z2, Z3 and their reactive resistances X1, X2, X3 are calculated when transforming the resistance triangle circuit T1 from a triangle to a star, while the active component of the resistance in 110 kV networks is not taken into account and the reactive resistance X is taken into account in the calculations, which is distinguished by the fact that - that the third TP3 and fourth TP4 traction substations are introduced into it, connected to the external power supply system respectively through the introduced beams of resistance of power transmission lines ZT2 ₀₂ and ZT3 ₀₁ , connected to the node (1) of the power source and traction substations TP3 and TP4, and the resistance of the "jumpers" ZT2 ₁₂ and ZT3 ₁₂ , respectively connected between the inputs of transformers TP3 with TP1 and TP2 with TP4, and as a result, three equivalent triangles of resistance of the SVE T1, T2, T3 are obtained, to which traction substations TP1, TP2, TP3 and TP4 are connected, wherein the three inter-substation zones of the single-phase traction network have different power phases, - resistances ZT2 ₀₂ and ZT3 ₀₁ are determined in systems of two equations with short-circuit resistances specified from the RDU, respectively, at the inputs TP3 and TP1 when calculating ZT2 ₀₂ and at the inputs TP2 and TP4 when calculating ZT3 ₀₁ , and by analogy with the calculations of the equivalent triangle of resistances T1, the parameters X1, X2, X3 of the transformed star of equivalent triangles T2 and T3 are determined by their resistances, - thus, knowing the resistance of the power system, the resistance of traction substations, the following are determined: - when powered by T1: - when powered by T2: - when powered by T3: - the voltages of their supply arms are determined by the resistances of traction substations, the voltage loss of the supply arm from “its” load is determined by the product of this load and the resistance, however, when calculating the voltage losses from the load of adjacent substation zones, the leading or lagging phases should be taken into account, in particular, for the inter-substation zone TP1-TP2 “its” loads I _A and I _B , and the currents I ₁ and I ₂ are formed from adjacent inter-substation zones, - if the power supply arm of the inter-substation zone under consideration is connected to the leading phase, then the voltage of this arm, according to known calculations, is equal to - if the power supply arm of the inter-substation zone under consideration is connected to the lagging phase, then the voltage of this arm is equal to where U ₁₂ is the supply arm voltage determined taking into account the voltage losses from the load of only “its own” considered inter-substation zone TP1-TP2.

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