CN108988368B - Unbalance leveling method for n-shaped wiring capacitor set - Google Patents

Unbalance leveling method for n-shaped wiring capacitor set Download PDF

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CN108988368B
CN108988368B CN201810892386.XA CN201810892386A CN108988368B CN 108988368 B CN108988368 B CN 108988368B CN 201810892386 A CN201810892386 A CN 201810892386A CN 108988368 B CN108988368 B CN 108988368B
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capacitor
unbalance
capacitor bank
leveling
bank
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CN108988368A (en
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郑伟
黄义隆
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Maintenance and Test Center of Extra High Voltage Power Transmission Co
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Measurement Of Resistance Or Impedance (AREA)

Abstract

The invention discloses an imbalance leveling method for an n-shaped wiring capacitor set, which comprises the following steps of: determining parameters, leveling standards and unbalance degrees of the capacitor bank; disconnecting the capacitor bank from the high-voltage bus; applying alternating voltage to the capacitor bank, observing the unbalance degree generated by the protection device, and comparing the unbalance degree with an unbalance degree leveling standard; if the unbalance degree generated by the protection device meets the leveling standard, the work is finished; if the capacitance value does not meet the preset value, measuring the capacitance values of the capacitor unit in the capacitor bank bridge arm and the capacitor unit in the capacitor bank bridge arm, and replacing the capacitor unit with larger capacitance value deviation; and sequencing the capacitor units according to the capacitance values, and performing pairwise exchange on the positions of the capacitor units on different bridge arms for a plurality of times according to a leveling target so as to level the unbalance degree to a set value. The invention can essentially reflect the unbalance condition of the capacitor bank, can avoid the unbalance protection action after the capacitor bank is put into operation after leveling, and has high operation efficiency.

Description

Unbalance leveling method for n-shaped wiring capacitor set
Technical Field
The invention relates to the technical field of maintenance of power transmission and transformation engineering equipment, in particular to an unbalanced degree leveling method for an n-shaped wiring capacitor bank.
Background
The current high-voltage capacitor group more adopts pi type wiring, and main protection is unbalance protection, and unbalance protection adopts unbalanced current to divide with the electric current and obtains the unbalance degree. When the degree of unbalance is small, the fault degree in the capacitor bank is light, and an alarm outlet is protected; when the unbalance degree is large, the fault degree in the capacitor bank is serious, and a tripping outlet is protected. The capacitor units connected in series and parallel with the capacitor bank are numerous, the fixed value of the unbalanced protection alarm section is set to be a certain fault working condition in one capacitor unit, and the sensitivity is high. After the capacitor bank is installed or overhauled on site, the capacitor bank is leveled, so that unbalanced current generated under the condition of applying a certain voltage is smaller than a certain value. However, the existing method for leveling is poor in effect, and an event that the unbalanced protection immediately acts and trips after the capacitor bank is put into use occurs.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide an imbalance leveling method for an n-type connection capacitor bank, which improves the scientificity and effectiveness of imbalance leveling of the capacitor bank.
An imbalance leveling method for an n-type wiring capacitor bank adopts n-type wiring as a high-voltage capacitor bank of an alternating current filter, a direct current filter or a parallel capacitor in power transmission and transformation engineering, and mainly comprises a capacitor bridge arm C1, a capacitor bridge arm C2, a first current transformer IT1 connected with the capacitor bridge arm C1 in series, and a second current transformer IT2 connected with the capacitor bridge arm C2 in series, wherein each capacitor bridge arm is formed by connecting a plurality of capacitor units in series and in parallel, and the imbalance leveling method comprises the following steps:
step 1: determining the parameters of the capacitor bank: the circuit comprises rated capacitance and a series-parallel connection structure of 2 capacitor bridge arms, rated voltage, rated current and tuning frequency of an alternating current filter, a direct current filter or a parallel capacitor, and model, rated capacitance, rated voltage and rated capacity of a capacitor unit;
step 2: determining the imbalance leveling standard of the capacitor bank: setting the capacitor bank unbalance leveling standard to be not more than half of the capacitor bank unbalance protection alarm section unbalance fixed value according to the capacitor bank unbalance protection fixed value;
and step 3: determining the imbalance of the capacitor bank by the following equation:
Figure BDA0001757285030000021
wherein, IT1The value of the current flowing through the first current transformer IT1, IT2Is the value of the current flowing through the second current transformer IT2, C1、C2The capacitance values of the capacitor bridge arms C1 and C2 are respectively;
and 4, step 4: disconnecting the capacitor bank from the high-voltage bus;
and 5: applying alternating voltage to the capacitor bank by using an alternating current power supply, enabling the capacitor bank to flow alternating current, observing the unbalance degree generated by the protection device, comparing the unbalance degree with the unbalance degree leveling standard, and finishing the work if the unbalance degree generated by the protection device meets the unbalance degree leveling standard; if not, entering the next step;
step 6: measuring and recording capacitance values C of 2 capacitor bridge arms of capacitor bank1And C2Measuring and recording the capacitance value of each capacitor unit on 2 capacitor bridge arms;
and 7: comparing the deviation between the actually measured capacitance value and the rated capacitance value of each capacitor unit, and replacing the capacitor units with the deviation larger than 2%;
and 8: sorting each capacitor unit of 2 capacitor bridge arms by taking the bridge arms as groups according to the size of the capacitance value;
and step 9: according to C1＝C2The leveling target of (2) is to exchange the positions of the capacitor units on the capacitor bridge arms in pairs;
step 10: after the exchange is finished, applying alternating voltage to the capacitor bank by using an alternating current power supply, enabling the capacitor bank to flow alternating current, observing the unbalance degree generated by the protection device, comparing the unbalance degree with the unbalance degree leveling standard, and finishing the work if the unbalance degree generated by the protection device meets the unbalance degree leveling standard; if not, steps 9 and 10 are repeated.
The invention has the beneficial effects that:
unbalance degrees are adopted to replace unbalanced currents to serve as investigation quantity of capacitor bank leveling, and the unbalance condition of the capacitor bank can be reflected substantially; half of the unbalance constant value of the capacitor bank unbalance protection warning section is used as the unbalance leveling standard of the capacitor bank, so that the unbalance protection action after the capacitor bank is put into operation after leveling can be avoided; by adopting the capacitor unit capacitance value sequencing and pairwise exchanging method, the leveling target can be realized after two to three times of exchange, and the efficiency is higher.
Drawings
FIG. 1 is a schematic diagram of a Pi-type wiring capacitor bank;
FIG. 2 is a schematic diagram of a capacitor unit structure of capacitor bridge arm C1;
fig. 3 is a schematic diagram of the current distribution of the pi-type wiring capacitor group.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic structural diagram of an n-type connection (also called branch connection) capacitor bank as a high-voltage capacitor bank of an ac filter of a converter station in dc transmission engineering, which includes a capacitor arm C1 and a capacitor arm C2, each capacitor arm is formed by connecting a plurality of capacitor cells in series and parallel, and in this embodiment, the structures of the C1 and the C2 arms are 20 series and 2 parallel (as shown in fig. 2). A first current transformer IT1 is connected below the capacitor arm C1, a second current transformer IT2 is connected below the capacitor arm C2, and the difference between the two arm currents (IT 2)1﹣IT2) The sum of the currents of the two arms (IT) for unbalanced current1+IT2) Is the sum current flowing through the entire capacitor bank (as shown in figure 3). The method comprises the following steps of overhauling and leveling after the unbalanced protection action of the capacitor trips at a certain time:
step 1: determining the parameters of the capacitor bank: the circuit comprises rated capacitances and series-parallel connection structures of 2 capacitor bridge arms, rated voltages, rated currents and tuned frequencies of an alternating current filter, models, rated capacitances, rated voltages and rated capacities of capacitor units, wherein the structures of the C1 and C2 bridge arms are 20 series-2 parallel;
step 2: determining the imbalance leveling standard of the capacitor bank: according to the fixed value of the capacitor bank unbalance protection, the capacitor bank unbalance leveling standard is set to be not more than half of the fixed value of the capacitor bank unbalance protection warning section unbalance, in the embodiment, the fixed value of the capacitor bank unbalance protection warning section unbalance is 0.32%, and the half is 0.16%;
and step 3: determining the imbalance of the capacitor bank by the following equation:
Figure BDA0001757285030000031
wherein, IT1The value of the current flowing through the first current transformer IT1, IT2Is the value of the current flowing through the second current transformer IT3, C1、C2The capacitance values of the capacitor bridge arms C1 and C2 are respectively;
and 4, step 4: disconnecting the capacitor bank from the high-voltage bus;
and 5: applying alternating voltage to the capacitor bank by using an alternating current power supply, enabling the capacitor bank to flow alternating current, observing the unbalance degree generated by the protection device, and comparing the unbalance degree with the unbalance degree leveling standard, wherein in the embodiment, the unbalance degree is certainly greater than the leveling standard due to tripping of the unbalance protection action;
step 6: measuring and recording capacitance values C of 2 bridge arms C1 and C2 of the capacitor bank1、C2Measuring and recording the capacitance value of each capacitor unit on 2 bridge arms;
and 7: comparing the deviation between the actually measured capacitance value and the rated capacitance value of each capacitor unit, and replacing the capacitor units with the deviation larger than 2%, wherein only 1 capacitor unit is replaced in the embodiment;
and 8: sorting the capacitor units on the 2 bridge arms by taking the bridge arms as groups according to the capacitance values;
and step 9: according to C1＝C2The leveling target of (2) is to exchange the positions of the capacitor units on the bridge arms in pairs;
step 10: after the exchange is finished, applying alternating voltage to the capacitor bank by using the alternating current power supply again, enabling the capacitor bank to flow alternating current, observing the unbalance degree generated by the protection device, comparing the unbalance degree with the unbalance degree leveling standard, and finishing the work if the unbalance degree generated by the protection device meets the unbalance degree leveling standard; if not, continuing to carry out the capacitor unit interchange work of the step 9 until the unbalance degree generated by the protection device meets the unbalance degree leveling standard, in the implementation, after actually carrying out pairwise interchange of 2 capacitor units, the unbalance degree meets the unbalance degree leveling standard, and the work is finished.
The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention accordingly, and not to limit the protection scope of the present invention accordingly. All equivalent changes or modifications made in accordance with the spirit of the present disclosure are intended to be covered by the scope of the present disclosure.

Claims (1)

1. An n-type wiring capacitor bank unbalance leveling method is characterized in that an n-type wiring is adopted in a capacitor bank to serve as a high-voltage capacitor bank of an alternating-current filter, a direct-current filter or a parallel capacitor in power transmission and transformation engineering, the capacitor bank unbalance leveling method mainly comprises a capacitor bridge arm C1, a capacitor bridge arm C2, a first current transformer IT1 connected with the capacitor bridge arm C1 in series and a second current transformer IT2 connected with the capacitor bridge arm C2 in series, each capacitor bridge arm is formed by connecting a plurality of capacitor units in series and parallel, and the capacitor bank unbalance leveling method is characterized in that: the unbalance leveling method comprises the following steps:
step 1: determining the parameters of the capacitor bank: the circuit comprises rated capacitance and a series-parallel connection structure of 2 capacitor bridge arms, rated voltage, rated current and tuning frequency of an alternating current filter, a direct current filter or a parallel capacitor, and model, rated capacitance, rated voltage and rated capacity of a capacitor unit;
step 2: determining the imbalance leveling standard of the capacitor bank: setting the capacitor bank unbalance leveling standard to be not more than half of the capacitor bank unbalance protection alarm section unbalance fixed value according to the capacitor bank unbalance protection fixed value;
and step 3: determining the imbalance of the capacitor bank by the following equation:
Figure FDA0002511480490000011
wherein, IT1The value of the current flowing through the first current transformer IT1, IT2Is the value of the current flowing through the second current transformer IT2, C1、C2The capacitance values of the capacitor bridge arms C1 and C2 are respectively;
and 4, step 4: disconnecting the capacitor bank from the high-voltage bus;
and 5: applying alternating voltage to the capacitor bank by using an alternating current power supply, enabling the capacitor bank to flow alternating current, observing the unbalance degree generated by the protection device, comparing the unbalance degree with the unbalance degree leveling standard, and finishing the work if the unbalance degree generated by the protection device meets the unbalance degree leveling standard; if not, entering the next step;
step 6: measuring and recording capacitance values C of 2 capacitor bridge arms of capacitor bank1And C2Measuring and recording the actually measured capacitance value of each capacitor unit on 2 capacitor bridge arms;
and 7: comparing the deviation between the actually measured capacitance value and the rated capacitance value of each capacitor unit, and replacing the capacitor units with the deviation larger than 2%;
and 8: sorting each capacitor unit of 2 capacitor bridge arms by taking the bridge arms as groups according to the size of the actually measured capacitance value;
and step 9: according to C1＝C2The leveling target of (2) is to exchange the positions of the capacitor units on the capacitor bridge arms in pairs;
step 10: after the exchange is finished, applying alternating voltage to the capacitor bank by using an alternating current power supply, enabling the capacitor bank to flow alternating current, observing the unbalance degree generated by the protection device, comparing the unbalance degree with the unbalance degree leveling standard, and finishing the work if the unbalance degree generated by the protection device meets the unbalance degree leveling standard; if not, steps 9 and 10 are repeated.
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