CN218772023U

CN218772023U - Structure for reducing stray capacitance influence of capacitor bank for extra-high voltage direct current transmission

Info

Publication number: CN218772023U
Application number: CN202120603298.0U
Authority: CN
Inventors: 吕永生
Original assignee: Yongjin Capacitor Co ltd
Current assignee: Yongjin Capacitor Co ltd
Priority date: 2021-03-24
Filing date: 2021-03-24
Publication date: 2023-03-28
Anticipated expiration: 2031-03-24

Abstract

The utility model discloses a reduce structure of special high voltage direct current capacitor bank stray capacitance influence for transmission of electricity. The capacitor bank comprises a plurality of bridge arm capacitor groups, all the bridge arm capacitor groups are connected in series, each bridge arm capacitor group comprises a left bridge arm capacitor and a right bridge arm capacitor, the left bridge arm capacitor and the right bridge arm capacitor are connected in parallel, and the stray capacitors are connected between every two adjacent bridge arm capacitor groups. The utility model has the advantages that: the equipotential lines are connected by the structure, so that the influence of the stray capacitance on the capacitance of each bridge arm of the capacitor bank can be reduced as much as possible, the actual capacitance of each bridge arm of the capacitor bank is basically the same, and the reliability of relay protection is ensured.

Description

Structure for reducing stray capacitance influence of capacitor bank for extra-high voltage direct current transmission

Technical Field

The utility model belongs to the technical field of the relevant technique of electric power reactive compensation and specifically relates to indicate a structure that reduces extra-high voltage direct current capacitor bank stray capacitance influence for transmission of electricity.

Background

At present, bridge difference protection is adopted for capacitor protection in an alternating current filter capacitor bank for a converter station, and in order to ensure the reliability of relay protection (no misoperation), the capacitor deviation of each bridge arm of the capacitor bank is required to be very small (the ratio of the capacitances of each bridge arm is less than 1.0004), so that the capacitor deviation of the capacitor bank is required to be higher.

In order to ensure that the capacitance ratio of each bridge arm of the capacitor bank meets the requirement, each manufacturer generally adopts the following method: (1) Strictly controlling the capacitance deviation of a single capacitor (-1.8 to + 1.8%); (2) Trimming and partial installation work of the capacitor are well done in a factory, so that the on-site installation workload and debugging are reduced; (3) If the initial unbalanced current is larger (larger than 1/4 times of the alarm value) on site, the single capacitor of each bridge arm needs to be adjusted.

SUMMERY OF THE UTILITY MODEL

The utility model relates to an overcome and to have foretell not enough among the prior art, provide a can improve the structure of the special high voltage DC transmission capacitor bank stray capacitance influence of reduction of reliability.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a structure for reducing stray capacitance influence of a capacitor bank for extra-high voltage direct current transmission comprises the capacitor bank and stray capacitances, wherein the capacitor bank comprises a plurality of bridge arm capacitor banks, all the bridge arm capacitor banks are connected in series, each bridge arm capacitor bank comprises a left bridge arm capacitor and a right bridge arm capacitor, the left bridge arm capacitor and the right bridge arm capacitor are connected in parallel, and the stray capacitances are connected between every two adjacent bridge arm capacitor banks.

Because the number of the capacitor units connected in series is large, the distribution of stray capacitance has large influence on the capacitance deviation between the arms, and the connection of equipotential lines has large influence on the distribution of the stray capacitance. In order to reduce the influence of the distribution of the stray capacitance on the capacitance ratio of each bridge arm of the capacitor, the equipotential lines need to be connected by using the structure, so that the influence of the stray capacitance on the capacitance of each bridge arm of the capacitor bank can be reduced as much as possible. When the capacitor of each bridge arm of the capacitor bank has deviation and affects the reliability of the relay protection due to balancing or other reasons, the characteristic of stray capacitance distribution can be fully utilized, so that the actual capacitance of each bridge arm of the capacitor bank is basically the same, and the reliability of the relay protection is ensured.

Preferably, in two adjacent bridge arm capacitor groups, one end of the stray capacitor is connected to the left bridge arm capacitor of one of the bridge arm capacitor groups, and the other end of the stray capacitor is connected to the right bridge arm capacitor of the other bridge arm capacitor group.

Preferably, the left arm capacitor includes four capacitors, the four capacitors are divided into two groups, two capacitors in each group of capacitors are connected in series, the two groups of capacitors are connected in series, and one end of the stray capacitor is connected to a connection position of the two groups of capacitors.

Preferably, the left bridge arm capacitor comprises four capacitors, the four capacitors are divided into two groups, two capacitors in each group of capacitors are connected in series, the two groups of capacitors are connected in series, and one end of the stray capacitor is connected to the connection position of the two groups of capacitors.

The utility model has the advantages that: the equipotential lines are connected by the structure, so that the influence of the stray capacitance on the capacitance of each bridge arm of the capacitor bank can be reduced as much as possible, the actual capacitance of each bridge arm of the capacitor bank is basically the same, and the reliability of relay protection is ensured.

Drawings

Fig. 1 is a schematic structural diagram of the present invention.

In the figure: 1. bridge arm capacitor bank, 2 stray capacitors, 3 left bridge arm capacitors, 4 right bridge arm capacitors, and 5 capacitors.

Detailed Description

The invention is further described with reference to the accompanying drawings and the detailed description.

In the embodiment shown in fig. 1, a structure for reducing stray capacitance influence of a capacitor bank for extra-high voltage direct current transmission includes a capacitor bank and a stray capacitance 2, the capacitor bank includes a plurality of bridge arm capacitor banks 1, all the bridge arm capacitor banks 1 are connected in series, the bridge arm capacitor bank 1 includes a left bridge arm capacitor 3 and a right bridge arm capacitor 4, the left bridge arm capacitor 3 and the right bridge arm capacitor 4 are connected in parallel, and the stray capacitance 2 is connected between two adjacent bridge arm capacitor banks 1. In two adjacent bridge arm capacitor groups 1, one end of a stray capacitor 2 is connected to a left bridge arm capacitor 3 of one bridge arm capacitor group 1, and the other end of the stray capacitor 2 is connected to a right bridge arm capacitor 4 of the other bridge arm capacitor group 1. The left bridge arm capacitor 3 comprises four capacitors 5, the four capacitors 5 are divided into two groups, two capacitors 5 in each group of capacitors 5 are connected in series, the two groups of capacitors 5 are connected in series, and one end of the stray capacitor 2 is connected to the joint of the two groups of capacitors 5. The left bridge arm capacitor 3 comprises four capacitors 5, the four capacitors 5 are divided into two groups, two capacitors 5 in each group of capacitors 5 are connected in series, the two groups of capacitors 5 are connected in series, and one end of the stray capacitor 2 is connected to the joint of the two groups of capacitors 5.

Wherein: the rack is equivalent to two poles of the capacitor 5, the height of the interlayer porcelain bottle is equivalent to the distance between two pole plates, and the ground capacitance of the rack is not considered at all. The stray capacitance 2 affects the capacitance of the two parallel bridge arms, and because the number of layers is large and the left and right arms of the capacitor 5 are arranged back to back, the stray capacitance 2 affects the capacitance of the two parallel bridge arms basically the same. Because the number of the capacitor 5 units in series connection is large, the distribution of the stray capacitance 2 has a large influence on the capacitance deviation between the arms, and the connection of the equipotential lines has a large influence on the distribution of the stray capacitance 2. In order to reduce the influence of the distribution of the stray capacitance 2 on the capacitance ratio of each arm of the capacitor 5, the equipotential lines need to be connected by using the structure, so that the influence of the stray capacitance 2 on the capacitance of each arm of the capacitor bank can be reduced as much as possible. When the capacitor bank has deviation of capacitance of each bridge arm of the capacitor bank due to balancing or other reasons and the reliability of relay protection is influenced, the characteristic of the distribution of the stray capacitance 2 can be fully utilized, so that the actual capacitance of each bridge arm of the capacitor bank is basically the same, and the reliability of the relay protection is ensured.

Claims

1. The structure for reducing the influence of stray capacitance of the capacitor bank for extra-high voltage direct current transmission is characterized by comprising the capacitor bank and the stray capacitance (2), wherein the capacitor bank comprises a plurality of bridge arm capacitor banks (1), all the bridge arm capacitor banks (1) are connected in series, each bridge arm capacitor bank (1) comprises a left bridge arm capacitor (3) and a right bridge arm capacitor (4), the left bridge arm capacitor (3) and the right bridge arm capacitor (4) are connected in parallel and are arranged back to back, and the stray capacitance (2) is connected between two adjacent bridge arm capacitor banks (1).

2. The structure for reducing the influence of the stray capacitance of the capacitor bank for extra-high voltage direct current transmission according to claim 1, wherein in two adjacent bridge arm capacitor banks (1), one end of the stray capacitance (2) is connected to the left bridge arm capacitance (3) of one bridge arm capacitor bank (1), and the other end of the stray capacitance (2) is connected to the right bridge arm capacitance (4) of the other bridge arm capacitor bank (1).

3. The structure for reducing the influence of the stray capacitance of the capacitor bank for extra-high voltage direct current transmission according to claim 2, wherein the left arm capacitance (3) comprises four capacitors (5), the four capacitors (5) are divided into two groups, two capacitors (5) in each group of capacitors (5) are connected in series, the two groups of capacitors (5) are connected in series, and one end of the stray capacitance (2) is connected to the connection position of the two groups of capacitors (5).