SU913518A1 - High-voltage substation - Google Patents

Description

The invention relates to electrical engineering, in particular to the field of lightning protection of electrical power plants, and can be applied in power systems.

Known high-voltage substation with suitable power lines, on which is installed (s) three-phase (s) set (you) of protective devices (valve-type arresters or nonlinear surge arresters) [1].

However, the location of the mentioned protective devices only at the substation does not provide its equipment with sufficient reliability while protecting against storm waves running from the lines.

Closest to the proposed technical solution is a lightning protection circuit with the removal of valve arresters (or non-linear surge arresters) on the line, in which an additional set of arresters is installed on each passing line at some distance from the substation set of valve arresters. This distance should be HIGH VOLTAGE.

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kim so that the secondary wave reflected from the linear set of protective devices arrives at the substation after the first maximum of oscillations on the protective equipment [21

Electrical protection for such a scheme is achieved for substations located in areas with normal soils with a specific resistance of p <100 ohm-m. In these areas, the grounding resistance of the supports, as a rule, is no more than 10-150 ohms.

However, in areas with a ground resistivity of p> 100 Ohm.m, the grounding resistance of the supports is usually greater than 40—

50 ohms, and in some places even more than hundreds ohms. In this case, a reliable lightning protection of the electrical equipment of the substations is not ensured, and the gain in lightning protection from the removal of valve arresters on suitable lines along the cargo wave is practically lost. Thus, this scheme is characterized by an insufficiently high reliability of lightning protection of electrical equipment of substations in areas with high resistivity of soils,

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913518

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The purpose of the invention is to improve the reliability of protection against lightning overvoltages of electrical equipment of substations in areas with high specific resistance of the soil.

This goal is achieved by the fact that in ₅ high-voltage substations containing electrical equipment protected by at least one three-phase set of substation valve arresters, the slopes of which are connected to the ground loop of sub-, θ stations, and one set of linear valve arresters installed on each suitable to the substation of the power line and located at a given distance from the substation arresters, determined by the condition of arrival of the wave reflected from the linear set of ventilation or dischargers, to the substation after the first maximum of the overvoltage 'at the substation, the descents of each linear set of valve sections with ₂ θ rowers are connected to the grounding circuit of the substations through additional grounding conductors with low resistance. '

FIG. 1 shows the proposed substation. It comprises a set of three-phase ₂₅ the Vienna threshing arresters 1 installed at each substation to the appropriate line 2 at a distance _r 1 from the three-phase set of valve arresters in Scheme 3 substations protected equipment 4 and 5 and the additional earthing switch 6 connecting tolerances valve arrester 1 with contour grounding substation.

FIG. 2 shows current-voltage characteristics (IVC) of valve-type arresters (where curve 7 is the IVC ground loop of the support ³⁵ , 8 is the CVC of the discharger 1 itself, and 9 is the CVC of the discharger 1 with the support ground loop) ·

Substation equipment by limiting the amplitude of the waves acting on the substation equipment insulation works the following way ⁴⁰ conductive.

After the discharger 1 triggers to the substation, a wave may fall in the line, determined by the remaining voltage of the arrester 1 without taking into account the voltage drop in the ground resistance ²⁵ of the support, i.e. when the spark gap 1 is triggered, the remaining voltage across it is determined on curve 9 in FIG. 2 and _OST9 , representing the total voltage-current characteristic of the valve discharger 1 50

(curve 7 in Fig. 2) and the ground resistance of the support loop at the installation site of the protective device 1 (curve 8 in Fig. 2), and only curve 7, i.e. and _0ST7 . Thereby, a wave of Post size falls on the substation further along the line. ?> Anei _Ost , ₉ . Thus, the connection through an additional earthing 6 points a and b (see Fig. 1) eliminates the influence of the support ground resistance, which is extremely important for areas with high soil resistivity.

An additional grounding conductor 6 is a cable laid with a section of 3650 or 70 mm ^2, laid in the ground at a depth of about 0.5-0.8 m.

The substation scheme has been developed for lightning protection of substations in areas with a ground resistivity of the order of p - 5,000,200,000 ohm-m.

Claims (1)

Claim A high voltage substation containing electrical equipment protected by at least one three-phase set of substation valve arresters, the slopes of which are connected to the substation's grounding circuit, and one set of linear valve dischargers installed on each transmission line suitable for the substation and located at a specified distance from substation arresters, determined by the condition of the arrival of a wave reflected from a linear set of valve arresters, to the substation after the of the maximum overvoltage at the substation, characterized in that, in order to increase the reliability of protection against lightning overvoltage of the substation electrical equipment in areas with high ground resistivity, the slopes of each linear set of valve arresters are connected to the substation grounding circuit through additional grounding conductors with low resistance.