RU2567996C2 - Method for regulating power of compensation filter installation in railroad traction energy supply system - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: compensation filter installation (CFI) is switched on or off depending on values of measured actual displacement power factor tgφ_act at hours of high daily loads in the electric mains and CFI is switched off at hours of low daily loads at generated reactive power: tgφ_g._act = 0. Unit for computation of total voltage harmonic factor $$K_{{\text{U}}_{\text{(n)}}}$$

at busbars of 110 (220)kV and units for computation of displacement power factor for load tgφ and generated reactive power tgφ_g calculate $$K_{{\text{U}}_{\text{(n) off}}}$$

and tgφ_off at switched off CFI at hours of high loads supposing that CFI is in switched on position. CFI is switched off in conditions of $$K_{{\text{U}}_{\text{(n) off}}}\le K_{U_{\text{(n) perm}}}$$

and tgφ_off ≤ tgφ_perm, where $$K_{U_{(n)perm}}$$

and tgφ_perm are permitted values. At switched off CFI at hours of low loads actual value of $$K_{U_{(n)act}}$$

is measured and tgφ_g.on is calculated supposing that CFI is in switched on position. In conditions of $$K_{U_{\text{(n) act}}}\ge K_{U_{\text{(n) perm}}}$$

and tgφ_g.on = 0 CFI is switched on.

EFFECT: effective compensation of reactive power and reduced level of current and voltage harmonics.

1 dwg

Description

The invention relates to the electric power industry to regulate its mode, in particular to a traction power supply system for alternating current of railways for regulating reactive power flows and the level of harmonics of current and voltage.

Known regulatory document [1], which determines the limit values of the ratio of consumption of active and reactive power. According to it, the coefficient of reactive load power tgφ _(fact) for consumers connected to 110 kV networks should not be more than 0.5 during hours of large daily loads of the electric network, and the coefficient of reactive power generated in the electric network should be zero per hour small daily loads. The indicated periods of large and small daily loads are determined by the energy supply agreement, otherwise the hours from large hours are considered to be from 7 hours 00 minutes to 23 hours 00 minutes, and hours of small loads from 23 hours 00 minutes to 7 hours 00 minutes.

Filter-compensating installations used in traction power supply perform the functions of reactive power compensation and filtering of current and voltage harmonics [2, 3].

The principles of automation of power control of capacitive compensation units in traction AC networks were considered in [3].

As a prototype we use a method of regulating the power of a filter-compensating installation (PKU) [2, p. 84]. A method of regulating the power of a filter compensating installation (FCU) of a traction substation of a traction power supply system of 27.5 kV with a step-down transformer 110 (220) / 27.5 kV, equipped with a voltage control device, to the 27.5 kV buses of which the FCU is connected by switching on (off) ) PKU depending on the value of the measured actual coefficient of reactive power of the load tgφ _(fact) during hours of large daily loads of the electrical network and disconnection of PKU during hours of small daily loads of the electrical network for meeting the requirements for the generated reactive power: tgφ _{g (fact)} = 0, therefore, to comply with [1], at large daily loads, the PCF switches on and off for small ones.

The disadvantage of the considered method of regulating the power of a filter-compensating installation is that it does not take into account the requirements of GOST for the quality of electric energy [4] in terms of meeting the requirements for the values of the full voltage harmonic coefficient. Therefore, with this method of regulation, there may be cases when, with the PKU turned off, in order to reduce reactive power generation, an unacceptable mode arises in terms of voltage harmonics. In accordance with [4], the full harmonic coefficient of voltage in 110 kV networks should not be more than 2% (maximum value is 3%).

The purpose of the invention: to ensure the operating mode of the traction network that meets the requirements of regulatory documents by developing a method for regulating the power of a filter-compensating installation to effectively compensate for reactive power and reduce the level of harmonics of current and voltage.

To achieve this goal, a calculating device was introduced, including a unit for calculating the total voltage harmonic coefficient K _{U (n)} on 110 (220) kV buses, as well as a unit for calculating the load reactive power factor tgφ and generated reactive power tgφ _g , which when the PKU is turned on during large hours the daily loads of the electric network are calculated K _{U (n) from} and tgφ _from , but assuming the PKU is off, and if the conditions K _{U (n) from} ≤K _{U (n) add} and tgφ _from ≤tgφ _add (where К _{U ( n) add} and tgφ _add - permissible values), then the PKU is turned off, and when the PKU is off in hours of small daily loads, the actual value of K _{U (n) fact is} measured and tgφ g.on. is _calculated on the assumption that the PKU is on, and if K _{U (n) fact} ≥K _{U (n) additional} and tgφ _g.on = 0, then PKU turns on.

To prove the necessity of implementing the method of regulation indicated in the invention, we will analyze the possible variants of the traction network mode.

A. The period of large daily loads of the electric network. PKU is included.

A.1 K _{U (n)} ≤K _{U (n) extra} and tg _φot ≤tgφ _extra , where tgφ _extra - permissible value of the reactive power coefficient [1]. In this case, it is advisable to disconnect the PKU to prevent overcompensation of the reactive power in order to comply with the standard for voltage harmonics.

A.2 K _{U (n)} ≤K _{U (n) add} and tg _φot > tgφ _add . Disabling PKU is impractical, since the standard for reactive power factor will not be respected.

A.3 K _{U (n)} > K _{U (n) add} and tg _φot > tgφ _add . It is impractical to disconnect PKU, since the standards for reactive power factor and full voltage harmonic coefficient will not be observed.

A.4 K _{U (n)} > K _{U (n) additional} and tg _φot ≤tgφ _additional In this case, it is impractical to disconnect the PKU, since the standard for the full voltage harmonic coefficient will not be observed.

So, it has been proved that during heavy loads only with one mode K _{U (n)} ≤K _{U (n) add} and tg _φot ≤tgφ _add it is advisable to disconnect the PKU.

B. The period of small daily loads of the electric network. PKU is disabled.

B.1 K _{U (n)} ≤K _{U (n) add} and tan _φgfact = 0. Requirements [1] and [4] are respected. There is no need to enable PKU.

B.2 K _{U (n)} > K _{U (n) add} and tan _φg.fact = 0. Requirements [2] are not complied with; therefore, it is necessary to verify the possibility of including PKU. If in this case the requirement tgφ _g.fact = 0 is met, then the PKU should be included. However, it is possible that when the PKU is turned on, the condition K _{U (n)} ≤K _{U (additional)} will be satisfied, but the condition tg _φg.fact = 0 will not be satisfied. In this case, it is advisable to indicate in the energy supply agreement the conditions for the implementation of the regime in question.

The drawing shows a device that implements the proposed method of regulation.

Designations in the scheme:

1 - three-phase bus 110 kV;

2 - power transformer 110 / 27.5 kV with on-load tap-changer;

3 - measuring voltage transformers 110 kV;

4 - measuring current transformers (CT) of 27.5 kV buses;

5 - contact hours T for monitoring predetermined periods of large and small daily loads of the electric network;

6 - calculation device;

7 is a block for calculating the total voltage harmonic coefficient K _{U (n)} ;

8 - unit for calculating the coefficient of reactive power of the load tgφ and the coefficient of the generated reactive power tg φ _g ;

9 - bus voltage transformers 27.5 kV;

10 - busbars 27.5 kV;

11 - PKU configured to filter the third harmonic (150 Hz);

12 - PKU switch;

13 - capacitor bank PKU;

14 - PKU reactor;

15 - block contact switch PKU 12;

16 - rails.

17 - control command (enable / disable) PKU.

The methods for measuring the reactive power coefficient tgφ and the total harmonic coefficient K _{U (n) are} as follows. The reactive power factor is measured by a three-phase meter of active and reactive energy during a large daily load as the ratio of reactive energy to active for a controlled period of time, and, in addition, the reactive power factor during a small daily load of generated reactive power tgφ _{g is} measured.

The following formulas are used to determine the calculated reactive power factor and generated reactive power under the assumption that the PKU is turned off (on).

1. The mode is actually enabled PKU. The calculation is performed under the assumption of a disabled PKU

2. The mode of truly disabled PKU. The calculation is performed under the assumption that the PKU is turned on

where Q and P _{LOAD LOAD} - measured reactive and active power load,

Q _fku - rated power of PKU.

To measure the total harmonic coefficient K _{U (n),} there are currently a large number of instruments, in particular the Omsk IPC [5].

The following formulas are used to determine the calculated K _{U (n)} .

1. When the PKU is really disabled, but assuming its on state

where U _And is the measured harmonic voltage during the period of small loads with the PKU off, kV;

U _(h) - the measured voltage of the third harmonic on the 110 kV busbar of the traction substation with the PKU switched off, which will be filtered when the PKU is switched on, kV;

U ₍₁₎ is the voltage of the first harmonic on the tires 110 kV traction substation, kV.

2. When the PKU is really turned on, but assuming its disabled state

where U _AND is the measured harmonic voltage during the period of small loads with the PKU position on, kV;

U _(h) is the calculated voltage of the third harmonic on the 110 kV buses of the traction substation, which is filtered when the PKU, kV is turned on.

The phase voltage of the third harmonic U _(s) on the 110 kV buses is determined by the formula:

where I ₍₃₎ is the current of the third harmonic of the traction load on the side of the transformer winding 110 kV, A;

X ₍₁₎ is the input inductance of the external power supply system of the first harmonic to the busbar 110 kV traction substation, Ohm.

The input impedance is determined by the short-circuit power busbar 110 kV (S _sc, MBA), which is given grid

where U is the voltage of the buses equal to 110 kV.

In connection with the asymmetric load, the considered calculations are performed for each phase.

If the PKU is made two-stage with two sections at 150 and 250 Hz, then the voltages of the third U ₍₃₎ and fifth U ₍₅₎ harmonics will participate in (2) calculations.

Consider using the presented scheme, the implementation of the proposed method for regulating the power of PKU.

1. The period of heavy loads, PKU included.

In the calculating device 6, tgφ _{fact is} determined by measurements from voltage transformers 9 and current transformers 4 and by corresponding measurements by active and reactive energy counters in block 8 for a given period (for example, 1 min). At the same time, the full harmonic coefficient of the voltage is measured according to the data from voltage transformer 3 using the Omsk IVK. Next, the calculation of К _{U (n) from} and tgφ _{from is} carried _out under the assumption that the PKU is disabled (10) according to formulas (1a) and (2b), and if the conditions K _{U (n)} ≤К _{U (n) add} and tgφ _from ≤ tgφ _add , then PKU is disconnected by command 17.

The block contacts 15 of the PKU switch indicate a disconnected or switched on state of the PKU 11. Contact clocks T 5 form predetermined periods of periods of large and small daily loads of the electric network.

2. The period of small daily loads, PKU is disabled. The actual value of K _{U (n) is} measured and calculated in block 8 tgφ _g.on. , assuming the PKU is on, and if K _{U (n) fact} ≥K _{U (n) add} and tg _g.on = 0, then PKU turns on at command 17.

Thus, a single-stage power control of the FCU is realized. With multi-stage PKU, the proposed principle of power control does not change.

After the on / off operation of the FCU 11, if necessary, the voltage on the 27.5 kV buses is adjusted using the on-load tap-changer of the transformer 2.

Information sources

1. Order No. 49 dated February 22, 2007 “On the procedure for calculating the ratio of active and reactive power consumption for individual energy receivers (groups of energy receivers) of consumers of electric energy, used to determine the obligations of the parties in contracts for the provision of electric energy transmission services ( energy supply agreements). ”

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

3. German L.A., Serebryakov A.S. Adjustable capacitive compensation systems in traction power supply systems of railways. / Monograph. M .: MIIT, 2012 .-- 211 p.

4. GOST R 54149-2010. Electric Energy. Electromagnetic compatibility of technical equipment. Quality standards for electric energy in general-purpose power supply systems. M .: Standartinform, 2010.

5. Power quality management / II Kartashev, V. Tulsky and others. Ed. Yu.V. Sharova - Moscow: Publishing House MPEI, 2006. - 320 p.

Claims (1)

A method of regulating the power of a filter compensating installation (FCU) of a traction substation of a traction power supply system of 27.5 kV with a step-down transformer 110 (220) / 27.5 kV, equipped with a voltage control device, to the 27.5 kV buses of which the FCU is connected by switching on (off) ) PKU depending on the value of the measured actual coefficient of reactive power of the load

during hours of large daily loads of the electric network and disconnecting PKU during hours of small daily loads of the electric network to comply with the requirements for the actual generated reactive power:

characterized in that a calculating device is introduced, including a unit for calculating the total voltage harmonic coefficient

on 110 (220) kV buses, as well as a unit for calculating the load reactive power factor

and generated reactive power

which, when the PKU is turned on, during hours of large daily loads of the electric network, are calculated

and

, but on the assumption that the PKU is off, and if the conditions are met

and

where

and

- permissible values, then the PKU is turned off, and when the PKU is off during hours of small daily loads, the actual value is measured

and count

assuming PKU is on, and if

and

then PKU turns on.