RU2562830C1 - Power control method of transverse capacitive compensation unit in electric traction network - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention uses a computational unit connected to secondary winding of a voltage transformer, to a block contact of a switch of capacitive compensation (KU) and to a receiving telemechanics subsystem of a sectioning point. The computational unit determines voltage losses at activation (deactivation) of KU and compares to voltage losses, at which power losses will be minimum. Depending on the obtained current voltage losses, KU is activated or deactivated.

EFFECT: improving power control accuracy of a transverse capacitive compensation unit and improving reliability and economy of power supply to the electric traction network.

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Description

The invention relates to electric power supply of electric railways of alternating current, in particular to an automation system for transverse capacitive compensation (CC) installations in a traction network.

In [1], a method for regulating the control factor at the sectioning station was proposed; it is based on measuring the harmonics of 150 Hz of the electric rolling stock, which is 20 ... 30% of the main harmonic. However, a new rolling stock (for example, Peregrine Falcon) has a limited harmonic content, and therefore this method is not applicable in this case. In [2], a method was proposed for regulating the power of a power plant by voltage on the busbars of a power plant of a section for traction AC mains. We take this method as a prototype: A method for regulating the power of a transverse capacitive compensation installation in a traction network connected via a switch with a block contact to the bus of a telemechanized section section of a contact AC network, by turning it on and off depending on the voltage on the section post measured busbar wire voltage transformer.

We point out that in the traction power supply system, all traction substations and sectioning stations are telemechanized [3], that is, transmitting telemechanics are installed at the energy dispatch center and receiving telemechanics at the traction substations and sectioning stations.

The specified method [2] has a large error, since even with the presence of automatic voltage regulation devices at the traction substation, the voltage at the sectioning station for various reasons can fluctuate within 1-2 kV regardless of voltage losses in the traction network. This means that there may be a situation where, for example, by measuring the voltage on the busbars of the KU, it is necessary to turn on the KU, but in reality this is not necessary. For the same reason, the KU power control device according to the patent [4] also has a large error in determining the parameters by which the KU power should be adjusted.

The purpose of the invention is to improve the accuracy of power control KU post sectioning

To achieve this goal, a calculation unit has been introduced, connected to the secondary winding of the voltage transformer, to the block contact of the KU switch and to the receiving half-intelligence of the telemechanics of the sectioning post, and in the case of the disconnected KU, the voltage across the buses of the sectioning post is measured U _nc , kV, the voltage is recorded according to the telemechanics on the tires of the adjacent traction substation U _o , kV, and the calculation of the current value of the appropriate power KU according to the formula

Q _k = [27.5 (U _o -U _nc )] cosφ / Z _{k (s)} , Mvar,

where cosφ is the power factor of the traction load, and Z _{k (c)} , Ohm is the composite resistance of the connection unit of the sectioning post,

and if the obtained Q _k ≥0.5Q _ko (where Q _ko is the rated power of the KU, Mvar), then a command with a time delay to turn on the KU switch is given,

and when KU is turned on, the voltage on the tires of the sectioning station U _{nc (k)} , kV is measured, according to telemechanics, the voltage on the tires of the adjacent traction substation U _o , kV is recorded, the voltage loss I _k X _kk , kV is calculated, and the current value is calculated appropriate power KU according to the formula

Q _k = [27.5 (U _o -U _{nc (k)} -I _k X _kk )] cosφ / Z _{k (s)} , Mvar,

where I _k - current KU, A; X _kk - own node inductive resistance of the connection node KU, Ohm,

and if the received power Q _k ≤0.5Q _ko (where Q _ko is the rated power of the KU, Mvar), then a command is given with the time delay to open the KU switch.

To clarify the proposed method for regulating the power of KU, we consider the scheme of the post sectioning (PS) with KU (Fig. 1), on which the following notation is adopted:

1 and 2 - contact network of the first and second ways;

3 - air gaps of the contact network at the PS;

4 - sectioning post;

5, 6, 7, 8 - switches of feeders of the PS contact network;

9 - bus 25 kV substation;

10 - KU;

11 - switch KU;

12 - capacitor bank KU;

13 - reactor KU;

14 - rail (ground loop KU);

15 - voltage transformer PS;

16 - receiving half-set telemechanics PS;

17 - calculation unit;

18 - time relay;

19 - block contact switch KU 11.

Let us analyze the operation of the circuit that implements the proposed method of regulation. Sectioning station 4 is connected to the contact network of the first 1 and second 2 paths. The contact network is supplied from traction substations TP1 and TP2. The contact network is partitioned (air gaps 3) at the sectioning station 4. The calculations in block 17 are performed with the KU switched off or on, which is fixed by the block contact 19 of the KU 11 switch.

1. The control unit is disconnected, the block contact 19 is open. Information from the voltage transformer 15 U _nc and from the receiving half-set 16 of the telemechanics of the substation Uo is averaged every 10 ... 15 seconds and then, in block 17, the calculation is performed according to formula (1).

Q _k = [27.5 (U _o -U _nc )] cos _φ / Z _{k (c)} ,

and if the obtained value of KU power Q _k ≥0.5 _Qko , where Q _ko is the KU power, then a command is given (with a time delay of 18) to turn on the switch 11 of the KU.

2. The control unit is on, the block contact 19 is closed.

In the calculation unit 17, the calculation is performed according to the formula (2)

Q _k = [27.5 (U _o -U _{nc (k)} -I _k X _kk )] cosφ / Z _{k (c)} .

If the received Q _k ≤0.5Q _ko (where Q _ko is the rated power of the KU), then a command with a time delay of 18 to turn off the switch 11 of the KU is given.

Nodal resistances R _kk , R _ik and X _{kk are} easier to calculate using the RAST-05K program [7].

The invention contemplates a single-stage transverse capacitive compensation installation. However, the invention can be applied to multistage KU. In this case, it is necessary to change the value of Q _ko depending on the connected (disconnected) power of the KU stage. The technical and economic effect will be manifested in the fact that in connection with an increase in the accuracy of regulating the power of the KU, the reliability of the power supply of the electric power supply increases, since the voltage mode improves and the electric power losses in the traction network are further reduced, since the moments of switching on and off of the KU will be more accurately recorded.

Information sources

1. Invention No. 628580 A method for controlling the power of transverse capacitive compensation in a traction network with rectifier units (German L.A.). Application No. 2475480 of 04/13/77, publ. 10/15/78, bull. No. 38.

2. Mamoshin P.P., Efimov A.V. Scheme of automatic regulation of a single-phase compensating installation operating in voltage stabilization mode. Sat Proceedings of MIIT, issue 380 M .: MIIT, 1971, pp. 97-108.

3. Automation of power supply systems. Textbook for high schools. Yu.I. Zharkov, V.Ya. Ovlasyuk, N.G. Sergeev and others). M .: Transport, - 1990 - 359 s.

4. Utility model No. 133061. Adjustable installation of transverse capacitive compensation of the traction AC network of railways (German L.A., Kishkurno K.V.). Application No. 2013115314 dated April 05, 2013, published on 10/10/2013, bull. No. 28.

5. Marquardt K.G. Power supply of electrified railways. M .: Transport. 1982 - 528 p.

6. Karaev R.I., Volobrinsky S.D., Kovalev I.N. Electric networks and power systems. Textbook - M .: Transport, 1988, 326 p.

7. German L.A., Morozov D.A. Calculation of typical tasks of traction power supply of alternating current on a computer. Uch. pos. M .: MIIT 2010 - 59 p.,

APPENDIX A1. The principle of control KU in the traction network

Losses of active power in a traction network with a switchgear at a sectioning station (PS) in matrix form are equal

- вектор-столбец токов ЭПС (I₁, I₂… … …) и КУ (I_k); (Рассматриваем одноступенчатую КУ на ПС током I_k);Where $$I=\left|I_{\mathrm{one}},I_2,...I_k\right|$$

- the column vector of the EPS currents (I ₁ , I ₂ ... ... ...) and KU (I _k ); (We consider a single-stage CS at a substation current I _k );

R is the square matrix of the node active resistances of the contact network (nodes 1, 2, ... k), I ^t is the conjugated and transposed current value.

The minimum power loss is determined from (A1) by calculating the derivative dP / dI _k and equating it to zero.

As a result, we obtain the condition of minimum losses in the traction network:

that is, the voltage loss to the KU (node k) at the node active resistance R _kk from the KU current should be equal to the voltage loss from the reactive currents I _{pi of the} traction load to the KU.

At the sectioning station, the voltage is measured using a voltage transformer that determines - U _nc .

Then the voltage loss in the traction network to the PS is equal

where U _o - voltage on the tires 27.5 kV traction substation.

If KU is switched on at the substation, then the voltage loss to the substation is

where the indices ( _k ) indicate the included KU.

The voltage loss in the traction network ΔU _nc from the traction load is equal to [6].

Here I _p , I _q are the active and reactive components of the traction load currents, we believe that the cosφ of the traction load (of all electric locomotives) are the same. The expression (cosφ R _ik + sinφ X _ik ) = Z _{ik (c) is} usually called the composite resistance [5], which can be used in the calculation of traction networks with the installation of transverse capacitive compensation in the first approximation in the first harmonic, as indicated in [5] .

If Z _{ik (c) is} divided by R _ik , then the value a = Z _{ik (c)} / R _ik = (cosφ + q sinφ) is called the relative value of the composite resistance. Since for practical calculations the cosφ of all EPSs is usually assumed to be the same, and the ratio q = X _ik / R _ik is const, for any substation zone it can be practically assumed that a = const.

As can be seen (P4), the voltage loss ΣI _i R _ik can be determined by the measured voltage loss ΔU _nc

Since for the reactive current of the switchgear cosf = 0, a sinφ = 1, then the voltage loss to the switchgear from its reactive current, in particular, with unilateral supply of substations through the traction network, will be equal to I _k X _kk , that is, with a measured current I _k , calculate the voltage loss I _k X _kk for a known resistance X _kk .

As for the voltage losses ΣI _pi R _ik from reactive traction loads, they are calculated from the measured voltage losses from traction load without KU

Thus, to calculate ΣI _pi R _ik, it is necessary to measure ΔU _nc , which should be multiplied by cosφ / a. The values of X _kk , R _kk and R _ik for each inter-substation zone are easier to determine using the RAST-05K program [7].

When KU is switched on, voltage losses ΣI _pi R _{ik are} determined

ΣI _pi R _ik , = ΔU _{nc (k)} (cosφ) / a

From the aforesaid, an important conclusion follows on determining the optimal value of the KU current based on measurements of voltage losses, which we will arrange in the form of an algorithm.

A. KU is disabled.

1. The voltage measurement on the PS without KU U _nc .

2. Obtaining information on telemechanics about the voltage on the tires of 27.5 kV traction substations supplying the zone in question - U _o . If the voltages are different, then their average value is taken.

3. Determined ΔU _nc by the expression (P3).

4. Calculated (6p)

ΣI _pi R _ik , = ΔU _nc cosφ / a.

5. I _{k is} calculated from (A2) and (A6)

where Z _{kk (c)} = Z _{k (c)} is the composite resistance of the KU connection node.

6. The power factor is calculated, which would be optimal for the measured voltage loss (that is, in this case there would be the least power loss when the power factor is turned on by the formula (A7)).

7. If the obtained Q _k ≥0.5Q _ko (where Q _ko is the power of the KU), then a command with a time delay for turning on the KU is given.

B. KU is included.

1. The voltage measurement on the PS with KU - U _{nc (k)} .

2. Obtaining information on telemechanics about the voltage on the tires of 27.5 kV traction substations supplying the zone in question. If the voltages are different, then their average value is taken.

3. Determined by ΔU _{nc (k)} by the expression (P3a).

4. The voltage loss is calculated if the switchgear was turned off (that is, without taking into account the switchgear).

5. The KU current is calculated by analogy with (P7)

I _k = (U _o -U _{nc (k)} -I _k X _kk ) cosφ / Z _{k (c)} .

6. The current value of the appropriate power KU is determined by the formula (A8).

7. If the received Q _k ≤0.5Q _ko (where Q _ko is the power of the KU), then a command with a time delay to turn off the KU is given.

Claims (1)

The method of regulating the power of the transverse capacitive compensation installation in the traction network, connected through a switch with a block contact to the bus of the telemechanized sectioning station of the contact AC network, by turning it on and off depending on the voltage on the sectioning section bus measured by a two-winding voltage transformer, characterized in that a calculation block is introduced, connected to the secondary winding of the voltage transformer, to the block contact of the KU switch and to the receiving half-intelligence of the body The mechanic sectioning post, and in the case of disabled CG voltage measurement is made on the tires sectioning post U _nc, kV, according to remotely fixed voltage on the adjacent tire traction substation U _o, kV, and calculates the current value suitable for power KU formula
Q _k = [27.5 (U _o -U _nc )] cosφ / Z _{k (s)} , Mvar,
where cosφ is the power factor of the traction load, and Z _{k (c)} , Ohm, is the composite resistance of the connection unit of the sectioning post
and if the obtained Q _k ≥0.5 Q _ko (where Q _ko is the rated power of the KU, Mvar), then a command is given with the time delay to turn on the KU switch,
and when KU is turned on, the voltage on the tires of the sectioning station U _{nc (k)} , kV is measured, according to telemechanics, the voltage on the tires of the adjacent traction substation U _o , kV is recorded, the voltage loss I _k X _kk , kV is calculated, and the current value is calculated appropriate power KU according to the formula
Q _k = [27.5 (U _o -U _{nc (k)} -I _k X _kk )] cosφ / Z _{k (s)} , Mvar,
where I _k - current KU, A; X _kk - own node inductive resistance of the connection node KU, Ohm,
and if the received power Q _k ≤0.5Q _ko (where Q _ko is the rated power of the KU, Mvar), then a command is given with the time delay to open the KU switch.