RU2592862C1 - Voltage regulation method on alternating current traction station - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: method relates to a. c. power supply system of electric railways, namely to controlling voltage by means of transformer with on-load tap changer (OLTC) and series capacitance unit with uncontrolled and controlled sections included in the suction line. To achieve technical result it is necessary to measure input inductive resistance of the substation to buses 110 (220) kV and at current of suction line less than rated current of nonregulated section of series capacitance unit to determine the practicability of switching on (off) of controlled section of series capacitance unit for approximation of resistance of series capacitance unit to resistance of the substation.

EFFECT: technical result - increase of efficiency of joint operation of on-load tap changer (OLTC) and series capacitance unit with allowance for the balancing properties of series capacitance unit.

1 cl, 1 dwg

Description

The method relates to an alternating current power supply system of electric railways, namely, voltage regulation using a transformer with a voltage control device under load (URPN) and the installation of longitudinal capacitive compensation (UPC).

In traction substations for voltage regulation, transformers with voltage regulation under load (URPN) and longitudinal capacitive compensation (UPC) are used [1]. Known installation of longitudinal capacitive compensation (CPC) with an adjustable section included in the suction line of the traction substation of alternating current, effectively working in conjunction with URPN [1 and 2]. We take as a prototype a method of regulating voltage with a transformer URPN and installing longitudinal capacitive compensation of the CCP with an adjustable section according to article [3] and its implementation according to Fig. 3 of [3] (or Fig. 14.1 of [2]): A method for regulating voltage at an alternating current traction substation with two transformers with phase resistance Xm, equipped with a voltage regulator under load (URPN), and a two-section longitudinal capacitive compensation device (UPC) ) in the suction line tires 27.5 kW resistance unregulated section Xc1 and rated current Ic1, and adjustable connecting section, and the nominal current resistance CCP CCP Xc _Σ - Ic _Σ, by changing the transformation ratio transformers and inclusion Ia-off of the CCP-controlled section.

The lack of prototype. In [2] it is indicated that the regulated section of the CPC is turned on only when the second transformer is turned on and the load is increased. However, in [2], the balancing property of the UPC included in the suction line of the traction substation is not taken into account, which should significantly increase the efficiency of voltage regulation with the help of the URPN transformer.

The purpose of the invention: to increase the effectiveness of the joint work of the CPC and URPN taking into account the balancing properties of the CPC.

To achieve this goal, the input inductance of the substation to the buses 110 (220) kV Xbx is measured and, with a suction line current of less than Ic1, the value modules are compared with one transformer A1 and A2 turned on, where

and with two transformers B1 and B2 turned on, where

and if A1> A2 or B1> B2, then turn on the regulated section of the CPC, and if A1 <A2 or B1 <B2, then turn off the regulated section of the CPC, and only after switching the regulated section do the control valves to comply with the condition

where Umin and Umax are the maximum allowable bus voltage of 27.5 kV, and U is the current voltage value,

moreover, if the suction line current exceeds Ic1, then the resistance modules are not compared and the adjustable section is turned on

The main idea on which the invention is based is as follows. At a traction substation, the voltage is usually asymmetrical. Since the regulation with the help of the URPN is carried out simultaneously in three phases, with an increase in voltage in the phase with the lowest voltage, an increase in voltage can occur over the permissible values in the other phase. Therefore, an effective voltage regulation with the help of an SEC is possible with a symmetrical voltage, which is achieved when the resistance of the control device included in the suction line is equal to the resistance of the substation phase (which is equal to the phase resistance of the transformer (s) plus input resistance) [1]. It is assumed that all resistances are reduced to the same voltage, for example, to 27.5 kV. Therefore, the closer the resistance of the UPC approaches the resistance of the substation phase, the closer the mode of the traction substation approaches the symmetrical voltage. In connection with the foregoing, before regulating the voltage using the URPN, turn on and off the regulated section of the CPC so as to bring the resistance of the substation phase to the resistance of the CPC.

To explain the regulation method, we will present a scheme of a traction substation with transformers equipped with voltage regulation devices under load of a load-transfer control circuit, and a two-section control code.

The following notation is used in the circuit:

1 - buses 110 (220) kV;

2, 3 - transformers with URPN;

4 - tires 27.5 kV;

5 - neutral insert;

6 - contact network of the supply arms;

7 - installation of longitudinal capacitive compensation (CPC) in the suction line;

8 - unregulated section of the Code of Criminal Procedure;

9 - adjustable section of the CPC with a switching device 10;

11 - calculation unit;

12 - information about the input impedance Хвх;

13 - information about the resistance of the transformer and the CPC;

14, 15 - power arm transformers;

16 - control of the regulated section of the CPC;

17 - management URPN;

18 - rails.

Start - start the circuit if the condition (3) is not met.

The input inductive reactance of the substation is determined by simultaneously measuring the change in the phase voltage ΔU on the 27.5 kV buses and the change in current ΔI on the same phase [4]:

When the voltage goes beyond the permissible limits (3), the calculation unit 11 is started and, based on the initial information 12 and 13, the modules are calculated:

With one transformer turned on:

if Al> A2, then by command 16 the regulated section 9 is switched on by the switching apparatus 10, and if A1 <A2, then section 9 is turned off.

With two transformers turned on:

if B1> B2, then, on command 16, the regulated section 9 is switched on by switching device 10, and if B1 <B2, then section 9 is turned off.

After carrying out these measures with an adjustable section 9 of the CPC 7, command 17 is given to switch the URPN of transformers 2 and 3.

As an example, we will show the operation of the CCP and URPN with the following initial data: Xc1 = 2.5 Ohm, Xc _Σ = 1.5 Ohm, Xm = 2 Ohm. Usually, at this substation, during normal operation of the SHE Xxv = 0.5 Ohms and with one transformer turned on, an unregulated UPC section with Xs1 = 2.5 Ohms is turned on, and with two transformers turned on, an adjustable UPC section and Xc _Σ = 1.5 Ohms are additionally included.

In connection with the repair work in the external power supply system during measurements, Ххх = 1.2 Ohms was obtained. Then, with two transformers turned on,

Since B1 <B2, then with two transformers turned on and with a suction line current less than Ic1, the adjustable section should not be switched on. Indeed, the resistance of the substation (1.2 + 2/2) = 2.2 Ohms, the resistance of the unregulated section of the CPC is 2.5 Ohms, and when the regulated section is turned on 1.5 Ohms. As you can see, when you turn on the unregulated section of the CPC, its resistance (2.5 Ohms) will be less different from the resistance of the substation (2.2 Ohms) than when the regulated section is on (compare 2.2 Ohms with 1.5 Ohms).

Literature

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

2. German L.A., German V.L. Automation of power supply traction AC network. Monograph. M .: MGUPS, 2014, 174 p.

3. German L.A., Goncharenko V.P. The modern scheme of longitudinal capacitive compensation in the traction power supply system. Bulletin of RGUPS No. 2 (50) -2013, Rostov-on-Don, p. 12-17.

4. AC 1359853. A method of reducing surge currents in a traction network. Publ. 12/15/87. Bull. No. 46.

Claims (1)

Method of voltage regulation at an alternating current traction substation with two transformers with phase resistance Xm, equipped with a voltage regulation device under load (URPN), and a two-section installation of longitudinal capacitive compensation (UPC) in a suction line of 27.5 kV tires with an unregulated section resistance Xc1 and a nominal current Ic1, and the connecting section of adjustable resistance CPC Xc _Σ, and the nominal current Ic _Σ, by changing the transformation ratio of the transformer and on-off adjustable CPC section, wherein the measured input inductive reactance substation to the bus 110 (220) x € X kV and at a current Ic1 less suction line modules resistance values are compared with one switched transformer A1 and A2, where
A1 = | (Xbx + Xm) -Xc1 | and A2 = | (x € X + Xm) -Xc _Σ |,
and with two transformers B1 and B2 turned on, where
B1 = | (XBX + Xm / 2)) - Xc1 | and B2 = | (Xbx + Xm / 2) -Xc _∑ |,
and if A1> A2 or B1> B2, then turn on the regulated section of the CPC, and if A1 <A2 or B1 <B2, then turn off the regulated section of the CPC, and only after switching the regulated section do the control valves to comply with the condition
Umin <U <Umax,
where Umin and Umax are the maximum allowable bus voltage of 27.5 kV, and U is the current voltage value, and if the suction line current exceeds Ic1, then the resistance modules are not compared and include an adjustable section of the CCP.

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