KR20100093835A - Resin composition producing insulating material of a high voltage direct current cable for power transmission - Google Patents

Abstract

PURPOSE: A resin composition for manufacturing an insulation body of a high voltage direct current cable for a power transmission is provided to perform a stable high-voltage DC transmission. CONSTITUTION: A resin composition for manufacturing an insulation body of a high voltage direct current cable for a power transmission contains the following: 100 parts of base resin by weight including 80~95wt% of low-density polyethylene, and 5~20wt% of linear low-density polyethylene; and 1~5 parts of conductive polymer with the energy bandgap less than 1.5eV. The conductive polymer is poly(3,4-ethylenedioxythiophene).

Description

RESIN COMPOSITION PRODUCING INSULATING MATERIAL OF A HIGH VOLTAGE DIRECT CURRENT CABLE FOR POWER TRANSMISSION}

The present invention relates to a resin composition for preparing an insulator of a high voltage direct current transmission cable, and more particularly, to a resin composition for preparing an insulator for a high voltage direct current transmission cable having a composition for reducing the accumulation of space charge in the high voltage cable and improving the lightning voltage breakdown characteristics. will be.

Since power is proportional to the product of voltage and current, increasing the voltage at the time of power transmission reduces the current and reduces the wire ratio, and the wire of the same thickness can send more power. Therefore, in the large power system where large-capacity and long-distance transmission is desired, high-voltage transmission to increase the transmission voltage is essential in view of reduction of power loss, construction site problem, and increase of transmission capacity.

In order to transmit at high voltage, insulation technology for transmission equipment, transformer, and circuit breaker that can withstand high voltage is required. Also, problems such as corona noise, radio wave interference, and communication induction disturbance have been raised. As complementary technologies are being developed continuously, problems with them are gradually solved.

There are two types of power transmission methods, an AC transmission method and a DC transmission method. AC power transmission method is used because it is easy to change the voltage using a transformer. Single phase 2-wire, single phase 3-wire, three phase 3-wire and three phase 4-wire are available. Single-phase three-wire type is mainly used for low voltage distribution lines, and single-phase two-wire type is used for parts with a small load at the end. Three-phase four-wire type is good for large-scale customers, and three-phase three-wire type can be efficiently used for transmission lines. In the early days when electricity was used, direct current was mainly used. However, as three-phase exchange, which can easily increase and decrease voltage, is used, power generation, transmission, and distribution are mostly made of alternating current.

The direct current transmission method refers to the transmission of electrical energy by direct current voltage or current. The principle is to convert the AC power on the transmission side to the appropriate voltage, convert it to direct current with the forward converter, and then send it to the faucet through the transmission line. On the receiving side, the DC power is converted back into AC power by the reverse converter. This method has the advantage of being able to transport large amounts of power over a long distance and to interconnect the asynchronous power system, but due to the difficulty in transforming, it has mainly used alternating current to change the voltage freely. However, in recent years, as the performance of the thyristors, which are converters, has been improved, DC high voltages have been obtained. In addition, DC has been widely used for long distance transmission or cable transmission because DC has less power loss and higher stability than AC.

In other words, in the case of direct current transmission, there is no dielectric loss of the insulator in long distance and large capacity transmission compared with alternating current, and no facility for compensating for the invalidity to the charging current is unnecessary. Moreover, DC power transmission has various characteristics, such as being able to operate stably the insulation breakdown voltage of an insulator. Currently, high voltage DC cables for DC power transmission use an oil (OIL Filled) cable insulated with insulating oil and paper, but there is a disadvantage in that maintenance of oil supply facilities is required. On the other hand, related technologies have been developed such that crosslinked polyethylene cables, which require no maintenance for AC transmission, are comparable in performance to OF cables or MI (Mass Impregnated) cables.

Due to the advantage that no additional maintenance is required, attempts have been made to apply crosslinked polyethylene, which is used for alternating current transmission, to high pressure direct current transmission cables. However, when the power transmission is progressed by using a high-voltage DC power transmission cable, when the temperature of the insulator surrounding the cable rises, or when the negative impulse or polarity inversion is made, the problem that the insulation characteristic is significantly reduced occurs have. This is known to be due to the accumulation of long-lived space charges in a non-polar polyetherene or crosslinked polyethylene, without a single charge being trapped or discharged. Therefore, research has been made to prevent such an increase in space charge.

The present invention has been devised as a fruit under the technical background of various efforts and studies for solving the problems while the problems described above exist.

The problem to be solved by the present invention is to solve the problem caused by the accumulation of space charge in the cable for high voltage direct current transmission, high pressure direct current power transmission made by adding a conductive polymer to the material composition to reduce the space charge in the cable as described above An object of the present invention is to provide a resin composition for insulator production of a cable.

The resin composition for preparing an insulator of a high-voltage direct current transmission cable provided as a means for solving the problems of the present invention is 80 to 95% by weight of low density polyethylene having a specific gravity of 0.92 g / cm 3 or less and linear low density polyethylene having a specific gravity of 0.91 to 0.94 g / cm 3 to 20 Basic resin mixed with weight%; And 1 to 5 parts by weight of the conductive polymer, based on 100 parts by weight of the base resin.

At this time, it is preferable that poly (3,4-ethylenedioxythiophene) be used as the conductive polymer. Meanwhile, the poly (3,4-ethylenedioxythiophene) may be weakly expressed as PEDOT.

According to the present invention, the space charge accumulation in the high voltage direct current transmission cable is excellently reduced and the withstand voltage characteristics are improved, so that the high pressure direct current transmission is stably performed.

Hereinafter, the present invention will be described in detail with reference to examples, and detailed description will be made with reference to the accompanying drawings in order to help understanding of the present invention. However, embodiments according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

The present invention has a technical feature in reducing the accumulation of space charge by dispersing the conductive polymer in the insulating resin composition.

Conventional high voltage direct current transmission cable, the center conductor, the inner semiconducting layer surrounding the center conductor, the insulator layer surrounding the inner semiconducting layer, the outer semiconducting layer surrounding the insulator layer, the shielding layer surrounding the outer semiconducting layer, and the shielding It consists of an anticorrosive layer surrounding the layer.

The resin composition for preparing an insulator of a high-voltage direct current transmission cable provided as a means for solving the problems of the present invention is 80 to 95% by weight of low density polyethylene having a specific gravity of 0.92 g / cm 3 or less and linear low density polyethylene having a specific gravity of 0.91 to 0.94 g / cm 3 to 20 Basic resin mixed with weight%; And 1 to 5 parts by weight of the energy inhibiting band width of 1.5 eV or less based on 100 parts by weight of the basic resin.

With regard to the numerical range for the linear low density polyethylene content in the base resin, if it is out of this range, the breakdown voltage characteristic is lowered, which is not preferable.

Regarding the numerical range of the content of the conductive polymer, when the conductive polymer is not added or falls below the lower limit, a large amount of heterogeneous space charges are accumulated or it is difficult to ensure uniform dispersibility, which is not preferable because it exhibits low withstand voltage characteristics. However, if the upper limit is exceeded, the space charge accumulation is improved, but due to the excessive content, dispersibility problems such as partial cohesiveness may cause undesirable volume resistance and low withstand voltage characteristics.

In this case, PEDOT is preferably selected and used as a conductive polymer that satisfies the numerical condition of the energy ban band width. In the case of the conventional conductive polymer polypyrrole or polythiophene, the energy inhibiting band width is 2.5 eV and 2.0 eV, respectively, which is not preferable because the DC withstand voltage characteristics as in the present invention are not sufficiently expressed.

By using the resin composition having the composition of Examples (1 to 3) and Comparative Examples (1 to 5) divided as shown in Table 1 below, the test specimen from the sheet made by hot pressing at 180 ℃, 30 minutes After the preparation, the physical properties such as the space charge amount, DC withstand voltage, volume resistance, etc. were measured and shown in Table 2 below.

division
Example (1-3) Comparative example (1-5) One 2 3 One 2 3 4 5 LDPE 95 90 80 90 90 100 70 90 LLDPE 5 10 20 10 10 - 30 10 PEDOT 2.5 2.5 2.5 - 10 2.5 2.5 - Polypyrrole - - - - - - - 2.5 Crosslinking agent 2 2 2 2 2 2 2 2

In Table 1, LDPE represents low density polyethylene, LLDPE represents linear low density polyethylene, PEDOT represents poly (3,4-ethylenedioxythiophene), and 2,5-dimethyl-2,5 di ( Tertiary-butylperoxy) -hexane was used in an amount of 2 parts by weight relative to 100 parts by weight of the base resin formed by mixing the LDPE and LLDPE. The PEDOT was used as a conductive polymer component, and Comparative Example 5 used a polypyrrole having a larger energy restriction band in place of PEDOT in comparison with Example 2.

division Example (1-3) Comparative example (1-5) One 2 3 One 2 3 4 5 Space reduction Dong ++ Dong ++ Dong ++ This ++++ Dong +++ Dong ++ Dong ++ Dong ++ DC breakdown voltage (kV / mm) 158 160 158 130 140 138 139 150 Volume resistance (Ω㎝) 10 ¹⁶ 10 ¹⁶ 10 ¹⁶ 10 ¹⁵ 10 ¹⁴ 10 ¹⁶ 10 ¹⁶ 10 ¹⁶

In Table 2, the space charge amount was measured by a pulsed electro-acoustic method before and after applying 40kV / mm to a 1mm sheet, and the amount of accumulated charge was expressed as a number of +. Looking at, 'dong ++' or 'dong +++' denoted in the space charge amount item of Table 2 indicates that the charge was generated by the injection of homogenous charge (Homocharge) having the same polarity of the electrode, '+' It is the number of times, indicating the relative amount of accumulated charge. Thus, 'dong ++' and 'dong +++' indicate that the charge property is the same as that of 'dong +', but the accumulated charge amount is two and three times, respectively. On the other hand, the meaning of 'yi', denoted by '+ + +' in the space charge category, indicates that heterocharges having polarities opposite to those of the electrodes have been accumulated. This indicates that charge accumulation was caused by impurities. The DC withstand voltage characteristic was measured by the voltage at the time of insulation breakdown at 90 degreeC using a 0.1-mm sheet. The volume resistance measured the 1-mm sheet according to ASTMD257 standard.

 From the results shown in Table 2, in the case of the embodiment it can be seen that the amount of accumulated space charge is only the same or smaller than the comparative examples, in particular compared to Comparative Examples 1 and 2, the amount of accumulated space charge 2 / It can be seen that only three. In all embodiments, even if external impurities are present in the insulator, a small amount of homogeneous charge is formed and the withstand voltage characteristics are improved, and thus the stability of the DC power transmission cable is maintained.

Optimal embodiments of the present invention described above have been disclosed. Although specific terms have been used herein, they are used only for the purpose of describing the present invention in detail to those skilled in the art and are not intended to limit the scope of the present invention as defined in the claims or the claims.

Claims (2)

A basic resin in which 80 to 95 wt% of low density polyethylene having a specific gravity of 0.92 g / cm 3 or less and 5 to 20 wt% of linear low density polyethylene having a specific gravity of 0.91 to 0.94 g / cm 3 are mixed; And 1 to 5 parts by weight of the conductive polymer having an energy inhibiting band width of 1.5 eV or less with respect to 100 parts by weight of the basic resin; resin composition for manufacturing an insulator of a high-voltage direct-current transmission cable. The method of claim 1, The conductive polymer is a resin composition for insulator production of a high-voltage power transmission cable, characterized in that the PEDOT.