Direct-current controllable lightning arrester

Abstract

The utility model discloses a direct current controllable lightning arrester which comprises 14 lightning arrester elements connected in parallel, the 14 lightning arrester elements are divided into seven rows, and each row comprises two lightning arrester elements. The high-voltage end at the upper part of each lightning arrester element is connected with a top-end voltage equalizing plate which shares one high-voltage wiring terminal; the bottom low-voltage ends of all the lightning arrester elements are connected in parallel and then grounded, and form an electrical loop with the upper high-voltage end. And each lightning arrester element is formed by connecting 10 sections of lightning arrester element bodies in series. The utility model is applied to a direct current bus in a high-voltage direct current transmission system. The lightning arrester can bear direct-current voltage, operation overvoltage and lightning invasion wave overvoltage in the operation process. The volt-ampere characteristics of the direct-current controllable lightning arrester are respectively a controlled part and a fixed part of the lightning arrester. The direct current controllable lightning arrester can limit the operation overvoltage according to the change of the operation condition, and the lightning arrester has the characteristics of high rated voltage, low operation charge rate and high reliability when the system normally operates by controlling the input number of the resistor discs.

Description

Technical Field

[0001] The utility model belongs to the technical field of lightning arresters and relates to a direct current controllable lightning arrester. Background Art

[0002] DC controllable lightning arresters can be connected in parallel to the 400kV DC bus to suppress overvoltage problems in the VSC system caused by transient faults. When the DC bus voltage is too high and exceeds the arrester's operating voltage, the DC controllable lightning arrester will be turned on, and the charge will be transferred to the ground through the controllable lightning arrester, reducing the voltage across the arrester and also reducing the voltage of the DC bus connected in parallel. When the DC bus voltage drops to the operating voltage of the DC controllable lightning arrester, the DC controllable lightning arrester automatically exits. At present, there is no such type of arrester product, which is difficult to meet actual work needs. Utility Model Content

[0003] The purpose of the utility model is to provide a DC controllable lightning arrester, which is installed in parallel on the DC busbar and is used to limit DC overvoltage, operating overvoltage and lightning intrusion wave overvoltage. The volt-ampere characteristics of the DC controllable lightning arrester are respectively the controlled part and the fixed part of the lightning arrester. The DC controllable lightning arrester can adjust the number of resistors put into operation according to the change of operating conditions, and realize the withdrawal and input of the controllable part of the lightning arrester, so as to fill the gap of this type of lightning arrester and meet the actual work needs.

[0004] The technical solution adopted by the utility model is: the lightning arrester includes 14 lightning arrester elements connected in parallel, and its characteristics are:

[0005] The 14 arrester elements are arranged in seven rows of two;

[0006] The upper high-voltage end of each arrester element is connected to the top voltage equalizing plate sharing a common high-voltage terminal;

[0007] The low-voltage end at the bottom of each arrester element is connected in parallel as a whole and then grounded to form an electrical circuit with the upper high-voltage end;

[0008] Each lightning arrester element is composed of 10 lightning arrester element bodies connected in series.

[0009] The utility model acts on the DC bus in the high-voltage DC transmission system. It can withstand DC voltage, operating overvoltage and lightning intrusion wave overvoltage during operation. The volt-ampere characteristics of the DC controllable lightning arrester are respectively the controlled part and the fixed part of the lightning arrester. The DC controllable lightning arrester can limit the operating overvoltage according to the changes in operating conditions. By controlling the number of resistors put into operation, the lightning arrester can have the characteristics of high rated voltage, low operating charge rate and high reliability when the system is operating normally. In transient conditions (when operating overvoltage or lightning intrusion wave overvoltage occurs), the number of resistors put into operation is reduced through a controllable switch, so that the action voltage of the lightning arrester is reduced, thereby limiting the bus overvoltage amplitude, and preventing the bus from breakdown due to operating overvoltage and lightning intrusion wave overvoltage.

[0010] The utility model has the characteristics of both EM arrester and DC bus arrester, which are as follows:

[0011] (1) The test applies a DC power supply with a charge factor higher than that of the DC bus arrester, which should not be less than 95%;

[0012] (2) The energy absorption capacity is much greater than that of EM arresters;

[0013] (3) Pancake-shaped high-performance DC resistors are used. The volt-ampere characteristics and heat dissipation effect of the parallel resistor are better than those of the ring-shaped ones, and there is no risk of central insulation breakdown;

[0014] (4) For each impact, the product's charge transfer capacity is not less than 1.1 times the declared charge;

[0015] (5) During the entire manufacturing process, each resistor is tested for electrical performance to ensure the consistency of resistor parameters. Through strict appearance inspection, resistors with appearance defects are eliminated to ensure product reliability.

[0016] (6) Current distribution

[0017] The test current waveform is 30 / 60us, and the test current value should not be greater than the current value required by the project; apply continuous operating voltage, measure the voltage borne by the controllable part and the fixed part respectively, and consider the uniform distribution inside each part. The charge rate borne by the resistor should not be higher than 82%;

[0018] (7) Add mechanical operation test at room temperature;

[0019] (8) Add insulation test for auxiliary and control circuits.

[0020] (9) Resistor energy screening:

[0021] A) Primary screening: Based on energy screening, if the qualified rate of resistors after energy screening is lower than 97%, the resistors in this batch are not allowed to be used in DC controllable lightning arresters.

[0022] B) If the secondary screening pass rate reaches 100%, the batch of resistors can be used in DC controllable lightning arresters.

[0023] C) When the secondary screening pass rate is lower than 99.5%, this batch of resistors shall not be allowed to be used in DC controllable lightning arresters.

[0024] D) When the secondary screening pass rate is lower than 100% but not lower than 99.5%, the batch of resistors should be screened for the third time.

[0025] E) The test current or voltage waveform of the tertiary screening is consistent with that of the secondary screening.

[0026] F) When the qualified rate of three screenings is 100%, the resistors in this batch can be used in DC controllable lightning arresters, otherwise, the resistors in this batch are not allowed to be used. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1a It is a structural schematic diagram of the utility model;

[0028] Figure 1b for Figure 1a A top view of

[0029] Figure 2 This is a schematic diagram of the structure of the U-shaped shielding ring of the utility model;

[0030] Figure 3 This is a schematic diagram of the external structure of the lightning arrester element body of the utility model;

[0031] Figure 4 This is a schematic diagram of the internal structure of the lightning arrester component body of the utility model.

[0032] In the figure: 1-top voltage equalizing plate; 2-high voltage terminal; 3-U-shaped shielding ring; 4-lightning arrester element body; 5-bottom connecting plate; 6-large umbrella; 7-small umbrella; 8-resistance sheet; 9-aluminum heat pipe; 10-insulating card pad; 11-current equalizing plate; 12-composite jacket. DETAILED DESCRIPTION

[0033] As shown in Figure 1, Figure 2As shown, the utility model lightning arrester includes 14 parallel lightning arrester elements, and the 14 lightning arrester elements are divided into seven rows, with two arranged in each row. The upper high-voltage end of each lightning arrester element is connected to the top voltage equalizing plate 1 that shares a high-voltage terminal 2. The bottom low-voltage end of each lightning arrester element is connected in parallel as a whole through the bottom connecting plate 5 and then grounded, forming an electrical circuit with the upper high-voltage end. Each lightning arrester element is composed of 10 sections of lightning arrester element bodies 4 connected in series. The upper end of the topmost lightning arrester element body 4 and the outer side of the connection between the lightning arrester element bodies 4 are provided with U-shaped shielding rings 3 connected to them, totaling 10. The total height of the utility model is about 8202mm, each section of the lightning arrester element body 4 is 800mm high, and the maximum outer umbrella diameter is The total weight is approximately 19,000kg.

[0034] like Figure 3 As shown, a composite jacket 12 is provided on the outside of each arrester element body 4, and the composite jacket 12 is arranged with large and small umbrellas 6 and 7 at intervals; the inner diameter of the composite jacket 12 is outer diameter The large umbrella 6 extends 63mm, the small umbrella 7 extends 47mm, the upper inclination angle of the umbrella is 16°, the lower inclination angle of the umbrella is 7°, the umbrella spacing is 70mm, and the creepage distance of the composite jacket 12 is not less than 2500mm. The larger creepage distance can greatly reduce the risk of product flashover and can operate safely and stably in an extremely dirty environment.

[0035] like Figure 4 As shown, each arrester element body 4 is provided with four parallel resistor columns, each resistor column is composed of 3-4 resistors 8 connected in series; the resistor columns are separated by aluminum heat pipes 9, and each resistor column is provided with a current equalizing plate 11 at both ends, which plays a role of forced voltage equalization, thereby reducing the current distribution coefficient between each resistor column, ensuring the consistency of the working conditions of all resistors 8, and thus ensuring the stability of the product. In terms of mechanical structure, in order to ensure the stability of the internal structure and improve the strength and seismic performance of the core frame, each core is provided with three insulating card pads 10.

[0036] The technical parameters of this utility model are shown in the following table:

[0037]

Claims

1. A DC controllable lightning arrester, comprising 14 lightning arrester elements connected in parallel, characterized in that: The 14 arrester elements are arranged in seven rows of two; The upper high-voltage end of each lightning arrester element is connected to a top voltage equalizing plate (1) that shares a common high-voltage terminal (2); The low-voltage end at the bottom of each arrester element is connected in parallel as a whole and then grounded to form an electrical circuit with the high-voltage end at the top; Each lightning arrester element is composed of 10 lightning arrester element bodies (4) connected in series.

2. A DC controllable lightning arrester according to claim 1, characterized in that: The upper end of the uppermost arrester element body (4) and the outer sides of the connection between the arrester element bodies (4) are provided with U-shaped shielding rings (3) connected thereto, with a total of 10 rings.

3. A DC controllable lightning arrester according to claim 1 or 2, characterized in that: A composite jacket (12) is provided on the outside of each lightning arrester element body (4), and the composite jacket (12) is arranged with large and small umbrellas (6, 7) arranged at intervals; the inner diameter of the composite jacket (12) is φ260 mm, and the outer diameter is φ300 mm; the large umbrella (6) extends 63 mm, the small umbrella (7) extends 47 mm, the upper inclination angle of the umbrella is 16°, the lower inclination angle of the umbrella is 7°, the distance between the umbrellas is 70 mm, and the creepage distance of the composite jacket (12) is not less than 2500 mm.

4. A DC controllable lightning arrester according to claim 1 or 2, characterized in that: Each lightning arrester element body (4) is provided with four parallel resistor plates, each resistor plate column is composed of 3-4 resistor plates (8) connected in series; the resistor plates are separated by aluminum heat pipes (9), and current equalizing plates (11) are provided at both ends of each resistor plate column.

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