RU2631873C1 - Electric potential regime actuating system in power distribution network - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: transformer substations (1) of different equipment are powered by a step-down power transformer (2) equipped with a load tap changing. The first control unit (6) is designed to affect the on-load tap changing of the transformer (2) and is placed on the substation (3). Measuring current transformers (9) and measuring voltage transformers (10) are installed on the part of transformer substations (for example, 1.1). The readings of the measuring transformers (7, 8 and 9, 10) are digitized by analog-to-digital converters (ADC) (11). Some of the transformer substations (1) are equipped with automatic compensators (12) of reactive power. The second control unit (14) is implemented on the basis of a programmable controller and is connected by digital channels (15) to the unit (6) and through the ADC (11) with measuring transformers (7-10). In addition, the unit (14) is connected by digital channels to the automatic compensators (12) of the substations (1.1).

EFFECT: increased reliability and stability of maintaining the permissible electric potential regime in the distribution network in which part of the territorially distributed transformer substations is not equipped with centralized and local control facilities, minimizing the number of voltage controller switching under the load of the power transformer supplying the network, increasing the network's hardware reliability.

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Description

Technical field

The invention relates to controlling the voltage mode in an alternating current distribution network by regulating the voltage of the supply transformer and reactive power compensation.

State of the art

A device is known for automatically controlling the voltage of an electric network, containing a control unit acting on a voltage regulator under load (RPK), which is equipped with a power transformer supplying a distribution network [RU 2280316]. The device comprises a voltage measuring transformer mounted on a power transformer and measuring its output voltage. The value of the measured voltage is transmitted through a single information channel to the control unit, which acts on the RPK, maintaining the output voltage of the power transformer in accordance with a given setting.

The disadvantage of this device is that it supports the output voltage of the supply power transformer without taking into account the current electrical state of the geographically distributed transformer substations of the network, to which the end users of the network are connected.

As a prototype of the selected device control the voltage mode in the electrical network, powered by a power transformer equipped with RPK [RU 2416855]. The prototype contains a control unit acting on the RPK, as well as voltage and current measuring transformers installed on the output of the power transformer and equipped with analog-to-digital converters in the connecting lines. Using the readings of the indicated measuring transformers, the control unit calculates the determining connection, according to the parameters of which, in accordance with the built-in algorithm, it decides whether it is necessary to influence the on-load tap-changer taking into account the settings of the selected operating mode and the state of the controller itself.

The disadvantage of the prototype is the low reliability and instability of maintaining the permissible voltage mode in a real distribution network containing geographically distributed transformer substations of various equipment, from the buses of which the end consumers of electricity are fed, as well as frequent on-load tap-changers, which reduce the service life and reliability of the power transformer.

Disclosure of the invention

The subject of the invention is a voltage control system in a distribution electric network powered by a power transformer equipped with an on-load tap-changer, comprising a first control unit acting on said regulator, and current and voltage transformers equipped with analog-to-digital converters installed at the output of the power transformer and, according to at least on the part of the transformer substations of the distribution network, characterized in that at least on the part of the transformer substations At the same time, automatic reactive power compensators were installed to support the voltage on the buses of transformer substations in accordance with the specified settings, and a second control unit was introduced, connected by digital channels to the first control unit and at least part of the automatic reactive power compensators and measuring transformers, the second control unit is configured to calculate the voltage on the buses of all transformer substations using data obtained by digital analogs, corrections of the indicated settings in case of calculated or measured voltages exceeding the permissible limits, and on-load tap-changer switching in case of insufficient such correction.

The technical result of the invention is to increase the reliability and stability of maintaining the permissible voltage regime in the distribution network, in which part of the geographically distributed transformer substations are not equipped with centralized and / or local control (for example, in the process of stage-by-stage modernization of the network), as well as minimizing the number of switching RPK power transformer supplying the network, and, therefore, to increase the hardware reliability of the network.

The implementation of the invention

The figure shows an example implementation of the inventive system and a fragmentary shown distribution network with transformer substations 1 low voltage supplying end consumers.

Transformer substations 1 of various equipment (1.1, 1.2, 1.3 are indicated in the figure) are powered by a step-down power transformer 2, equipped with a voltage regulator under the load of the RPK, switching the soldering of the secondary winding of the transformer 2 to change its output voltage. Transformer 2 is installed at medium voltage substation 3 (110 kV) and is connected by an output to bus 4, from which connecting lines 5 to substations 1 depart.

The first control unit 6 is designed to act on the RPK of the transformer 2 and is located in the substation 3.

At the output of transformer 2, a voltage measuring transformer 7 (10 kV) is connected to the bus 4, and current measuring transformers 8 on the connecting lines 5 (in a particular case, a current measuring transformer installed at the output of transformer 2 can be used).

On the part of the transformer substations (one of which is shown in the figure under the number 1.1), measuring current transformers 9 and voltage measuring transformers 10 are installed. The readings of measuring transformers 7, 8 and measuring transformers 9, 10 installed at substations 1.1 are digitized by analog-to-digital converters 11 (ADC).

Part of the transformer substations 1 (two of which are shown in the figure under the numbers 1.1 and 1.2) are equipped with automatic reactive power compensators 12 (AKRM). The function of the AKRM 12 is to maintain the voltage (0.4 kV) on the bus 13 of the substation 1 in accordance with a predetermined setting, for example, by switching a capacitor bank connected to the bus 13.

The second control unit 14 (BSU) is made on the basis of a programmable controller and is connected by digital channels 15 to block 6 and (via ADC 11) with measuring transformers 7, 8 and with measuring transformers 9, 10 installed in substations 1.1. In addition, block 14 is connected digital channels with automatic compensators 12 substations 1.1.

The voltage settings for AKRM 12 are set and corrected by block 14, and at substations 1.2, which operates locally - without communication with block 14, are set by maintenance personnel and are fixed in relation to the claimed control system.

Part of substations 1 (one of which is shown in the figure under number 1.3) may not be equipped with automatic compensators and measuring transformers.

Block 14 features include:

- calculation of voltages on tires 13 (0.4 kV) of transformer substations 1.2 and 1.3 using data obtained through digital channels 15;

- correction of the settings of those automatic compensators 9, with which the block 14 is connected by digital channels 15, if the voltage on the tires 13, obtained as a result of the calculation or measured by transformers 10, are outside the permissible limits;

- impact on block 6 to switch the tap-offs of transformer 2 using on-load tap-changer if the correction of the AKRM 12 settings is insufficient so that the voltages on all tires 13 (measured or obtained as a result of the calculation performed by block 14) fall within acceptable limits.

The inventive system operates as follows.

Before starting work, a working program is loaded into the memory of block 14, including a digital model of the distribution network, which allows determining the electrical modes of this network depending on the data received in block 14 via channels 15 (position of the on-load tap-changer of transformer 2, position of the transformer substation 12 of substations 1.1, readings of measuring transformers current and voltage), as well as information about the fixed settings of AKRM 12 set by the maintenance personnel at substations 1.2.

The programmable unit 14 in automatic mode with a period of, for example, one hour performs the actions on the following items:

a) Interrogation of digital channels 15 to update the readings of measuring transformers 8, 9 current and 7, 10 voltage, as well as data received via bidirectional digital channels, on the current positions of the tap changer of transformer 2 and AKRM 12 substations 1.1.

b) Determination (using the results of the survey and the known fixed settings of the ACRM of 12 substations 1.2) of the electrical mode of the distribution network based on its digital model loaded in the memory of unit 14. In this case, the measured readings are used to determine the voltages on the buses of 13 substations 1.1, and substations 1.2 and 1.3-calculated data obtained on the basis of the given fixed settings AKRM 12 and load currents. Block 14 can make up for the lack of measured readings on the load currents of some network lines from the predicted load profiles (for example, from the average seasonal-daily load profile for a given consumer).

c) In case of exceeding the permissible limits of the measured voltages on the tires 13 of the substation 1.1, block 14 calculates the correction set point for the associated substation 12 of the given substation.

d) In case of exceeding the permissible limits of the calculated voltages on the tires 13 of the substation 1.2, block 14 determines and stores in the electronic recommendations journal the required value of the fixed setpoint for the ACRM 12 of this substation.

e) Comparing the desired direction of voltage correction on the buses 13 of the substation 1.1 with the obtained data on the current position of the corresponding AKRM 12, the unit 14 checks the possibility of the required voltage change on the tires 13 by adjusting the setting with the corresponding automatic change of the current position of the AKRM 12. If the result is positive, check unit 14 sets the appropriate corrective settings. The negative result of the check, as well as the excess of the permissible limits of the calculated voltages on the tires 13 of the substation 1.2 with a fixed set of AKRM 12, as in point d), block 14 interprets as insufficient correction of the settings of AKRM 12 and the need to perform the following points f) and g) to switch On-load tap-changer of transformer 2.

f) Going through the possible on-load tap-changer positions (starting from the positions adjacent to the current one) and determining the network modes similarly to point b), block 14 determines the predicted voltage values on the buses 13 at different on-load tap-changer positions and selects the on-load tap-changer position at which the indicated predicted voltages are in acceptable limits at all substations of the network.

g) After a short time interval (for example, 180 seconds), block 14 re-performs the survey and calculations according to the above points a) - f) and, when confirming the need to correct the settings of the ACRM 12 or the effect on block 6 to switch the on-load tap changer, performs these actions.

As can be seen from the foregoing, the invention allows to maintain the permissible voltage mode in the distribution electric network, in which part of the geographically distributed transformer substations are not equipped with centralized and / or local control, and at the same time minimize the number of on-load tap-changer switching operations of the power transformer supplying the network.

Claims (1)

A voltage control system in a distribution electric network powered by a power transformer equipped with a voltage regulator under load, comprising a first control unit acting on the specified regulator, and current and voltage transformers equipped with analog-to-digital converters installed at the output of the power transformer and, according to at least on the part of the transformer substations of the distribution network, characterized in that at least on the part of the transformer sub On the other hand, automatic reactive power compensators are installed that support the voltage on the buses of transformer substations in accordance with the specified settings, and a second control unit is introduced, connected by digital channels to the first control unit and at least part of the automatic reactive power compensators and measuring transformers, the second control unit is configured to calculate the voltage on the buses of all transformer substations using data received by him digitally channels, said correction setting in case the calculated or measured for the stress limits and the voltage regulator switching under load in the event of failure of such a correction.

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