CN101984532B

CN101984532B - Thyristor dv/dt protection method

Info

Publication number: CN101984532B
Application number: CN201010512433.7A
Authority: CN
Inventors: 魏晓光; 王华锋; 陈龙龙
Original assignee: State Grid Corp of China SGCC; China Electric Power Research Institute Co Ltd CEPRI
Current assignee: State Grid Corp of China SGCC; China Electric Power Research Institute Co Ltd CEPRI
Priority date: 2010-10-12
Filing date: 2010-10-12
Publication date: 2014-03-12
Anticipated expiration: 2030-10-12
Also published as: CN101984532A

Abstract

The invention relates to the field of devices of power systems, in particular to a novel thyristor dv/dt protection method. The invention provides a dv/dt protection strategy by designing a direct current converter valve thyristor level dv/dt protection circuit. The novel thyristor dv/dt protection method can detect thyristor level dv/dt, adjust the protection level of a thyristor by detecting dv/dt and further achieve the purpose of protecting the thyristor. The protection circuit has simple structure and ingenious design method, and can better protect the thyristor from being damaged by over-high dv/dt.

Description

A kind of Novel thyristor dv/dt guard method

Technical field

The present invention relates to electric power system devices field, be specifically related to a kind of Novel thyristor dv/dt guard method.

Background technology

Converter valve is the most important primary equipment of DC transmission engineering; in converter valve running, may suffer the impact of steep wave, lightning wave, operation ripple; in order to trigger fast thyristor conducting; prevent that thyristor is destroyed, in design process, by measuring dv/dt value; thereby judgement is applied to the voltage condition on valve; when judgement dv/dt reaches level of protection value, trigger thyristor, reach the object of protection thyristor.

Converter valve may be subject to the impact of steep wave, lightning wave, operation ripple in running; because the speed that voltage rises is very fast; thereby in converter valve, produce very large voltage change ratio (dv/dt); this dv/dt may be fatal for thyristor; existing to causing thyristor to damage; thereby must when design thyristor electronic equipment, must consider dv/dt protective circuit, thereby reach the object of protection thyristor.

Because traditional DC transmission engineering is all the external direct-current transmission converter valve of buying; even this technology is monopolized by offshore company; because dv/dt protection implementation method and the protection strategy of converter valve thyristor are more difficult; and the rising along with thyristor junction temperature; the voltage withstand capability of thyristor can decline; the dv/dt level of protection value of thyristor also will decline accordingly; thereby the dv/dt of thyristor protection strategy is relatively complicated, even at present domestic, the dv/dt protective circuit of converter valve thyristor and protection strategy are not had to the comparatively theory analysis of specialty.This patent is under such technical background, to have designed dv/dt protective circuit, and this protective circuit is simple in structure, and method for designing is ingenious, for realizing the independent research of converter valve, has positive role.

In the power unit bypass machine of a patent CN200710041731.0 high-voltage frequency conversion and speed-adjusting device, mention and between thyristor module, be provided with the absorbing circuit that absorbs dv/dt.This patent is intended to utilize dv/dt absorbing circuit to reduce the dv/dt at thyristor two ends; this is a kind of very not intelligent method; and when dv/dt is excessive; dv/dt that absorption circuit absorbs ten minutes is limited; the designed dv/dt of this patent can, by dv/dt protection strategy is set, can reduces level of protection along with the increase of dv/dt, thereby reach the object of protection thyristor; convenient, flexible, reliable and secure.

Summary of the invention

Because excessive dv/dt can cause the damage of thyristor; cause the operation of DC converter valve to be broken down; the present invention is by the protective circuit of a kind of thyristor level dv/dt of design; a kind of dv/dt protection strategy of thyristor is provided; along with the increase of the dv/dt at thyristor two ends reduces the overvoltage protection level of thyristor, protection thyristor is avoided excessive dv/dt and is caused damaging.

The present invention proposes a kind of Novel thyristor dv/dt guard method, comprise the following steps:

(1) a kind of Novel thyristor dv/dt guard method is to consist of protective circuit and protection strategy, and described protective circuit comprises thyristor level circuit and dv/dt testing circuit;

(2) the thyristor level circuit in described protective circuit comprises thyristor T1, damping circuit and direct current grading resistor loop, described damping circuit comprises three terminal capacitor Cd1, Cd2 and Cd3, the high-pressure side of described capacitor C d1 and thyristor anodic bonding, the low-pressure end of described capacitor C d1 is connected with the high-pressure side of capacitor C d2, capacitor C d3, and capacitor C d2 is connected with damping resistance Rd3;

(3) described dv/dt testing circuit comprises the equal hydraulic circuit of direct current and dv/dt counter circuit, the equal hydraulic circuit of described direct current is by resistance R j1 and resistance R j2 series connection is rear and resistance R 5 is in series, resistance R j1, the measurement high-tension resistive of Rj2 and R5 thyristor voltage in series, these 3 resistance and resistance R 6 form bleeder circuit, by this voltage, divide hydraulic circuit effectively to measure the voltage at thyristor two ends, described dv/dt counter circuit is the capacitor C d3 by three terminal capacitor, resistance R d3, capacitor C 4 formation that is connected with resistance R 6, when thyristor two ends suffer the voltage of dv/dt, by this loop, certain electric current will be produced, current value is the product after dv/dt and capacitor C 4 and Cd3 series connection, after this current flowing resistance R6, will produce voltage, by the voltage of measuring on R6, can learn the dv/dt value that thyristor suffers.

Wherein, described dv/dt protection strategy is that the dv/dt suffering according to thyristor is larger, the ability of thyristor withstand voltage is lower, thereby when dv/dt is excessive, need to adjust the level of protection of thyristor, to reach the object of protection thyristor, the level of protection of described dv/dt is about 4～6kV/us, protection strategy is when the dv/dt of thyristor is less than level of protection, the overvoltage protection level of thyristor is constant, for 5kV～8kV, according to the design parameter of thyristor, set, when the voltage on thyristor is greater than level of protection, the overvoltage protection value of thyristor will be reduced to below 4kV.

The advantage of technical solution of the present invention is: taked effective dv/dt guard method, designed rational protective circuit, method is easy to realize, and protection strategy is comprehensively reliable.

Accompanying drawing explanation

In order to make content of the present invention by clearer understanding, and be convenient to the description of embodiment, provide accompanying drawing related to the present invention below and be described as follows:

Fig. 1 is dv/dt protection philosophy figure of the present invention;

Fig. 2 is the tactful allocation plan of protection;

Fig. 3 is thyristor dv/dt voltage protection test waveform schematic diagram when larger;

Fig. 4 is thyristor voltage protection test waveform schematic diagram while suffering lightning wave.

Embodiment

With reference to accompanying drawing 1; the designed converter valve thyristor level dv/dt protective circuit principle of this patent will be introduced in detail below; steep wave, lightning wave or operation ripple are applied to after thyristor; capacitor C d1, Cd2 from the thyristor utmost point, reach thyristor electronic equipment by resistance R d3, and dv/dt is by after capacitor C 4; generation current Ic4; Ic4 passes through after resistance R 6, generation current on R6, and its current value and dv/dt value are directly proportional.In electrical design, the level of protection of design thyristor level, as long as measure the voltage in resistance R 6, through calculating, can transform to the dv/dt of thyristor level.When dv/dt is greater than level of protection, TE produces thyristor triggering impulse, triggers thyristor conducting, makes thyristor avoid superpotential impact, thereby realizes the object of protection thyristor.

The protection strategy of thyristor and level of protection as shown in Figure 2, this Figure illustrates thyristor forward voltage and dv/dt protective feature curve, and dotted line represents the tolerance of thyristor, and solid line represents the dv/dt level of protection value of thyristor.Because the junction temperature along with thyristor raises; the forward withstand voltage of thyristor is lower; thereby in order to protect thyristor to avoid too high dv/dt; the level of protection value of dv/dt also should be along with reduction; according to this protection strategy, can realize thyristor dv/dt protection and reduce along with the reduction of the voltage tolerance of thyristor, from scheming: when dv/dt is excessive; it is faster that level of protection value reduces than the tolerance of thyristor, thereby realized the object to thyristor protection.

See accompanying drawing 3; the test waveform time is the every lattice of 2ms; protection action when 5ms; level of protection is about 5kV, and this is that dv/dt is now about 1V/us, and such dv/dt value and the product of C4+Cd3 are less; the electric current that flows through resistance R 6 is less; thereby the voltage in resistance R 6 is also smaller, the voltage ratio detecting on thyristor protection circuit is lower, thereby dv/dt protection is inoperative.

When thyristor is applied to lightning wave, see accompanying drawing 4, now the dv/dt of thyristor both end voltage is about 4kV/us.Dv/dt in circuit plays a role, and dv/dt protection has occurred.

Above by special embodiment content description the present invention, but those skilled in the art also can recognize the multiple possibility of modification and optional embodiment, for example, by combining and/or change the feature of single embodiment.Therefore, be understandable that these modification and optional embodiment will be considered as included in the present invention, scope of the present invention is enclosed patent claims and coordinate restriction thereof only.

Claims

1. a Novel thyristor dv/dt guard method, is characterized in that comprising the following steps:

(1) a kind of Novel thyristor dv/dt guard method is to consist of protective circuit and protection strategy, described protective circuit comprises thyristor level circuit and dv/dt testing circuit, described protection strategy is that the dv/dt suffering according to thyristor is larger, the ability of thyristor withstand voltage is lower, thereby when dv/dt is excessive, need to adjust the level of protection of thyristor, to reach the object of protection thyristor;

(2) the thyristor level circuit in described protective circuit comprises the equal hydraulic circuit of thyristor T1, damping circuit and direct current, described damping circuit comprises three terminal capacitor Cd1, Cd2 and Cd3, the high-pressure side of described capacitor C d1 and thyristor anodic bonding, the low-pressure end of described capacitor C d1 is connected with the high-pressure side of capacitor C d2, capacitor C d3, the low-pressure end of capacitor C d3 is connected with damping resistance Rd3, the low-pressure end of capacitor C d2 is connected with damping resistance Rd2, and the equal hydraulic circuit of described direct current is by resistance R j1 and resistance R j2 series connection is rear and resistance R 5 is in series;

(3) described dv/dt testing circuit comprises the equal hydraulic circuit of direct current and dv/dt counter circuit, the equal hydraulic circuit of described direct current is by resistance R j1 and resistance R j2 series connection is rear and resistance R 5 is in series, resistance R j1, the measurement high-tension resistive of Rj2 and R5 thyristor voltage in series, these 3 resistance and resistance R 6 form voltage and divide hydraulic circuit, by this voltage, divide hydraulic circuit effectively to measure the voltage at thyristor two ends, described dv/dt counter circuit is the capacitor C d3 by three terminal capacitor, resistance R d3, capacitor C 4 and resistance R 6 are in series, when thyristor two ends suffer the voltage of dv/dt, by dv/dt counter circuit, certain electric current will be produced, current value is the product after dv/dt and capacitor C 4 and Cd3 series connection, after this current flowing resistance R6, will produce voltage, by the voltage of measuring on R6, can learn the dv/dt value that thyristor suffers.

2. the method for claim 1, it is characterized in that: described protection strategy is that the dv/dt suffering according to thyristor is larger, the ability of thyristor withstand voltage is lower, thereby when dv/dt is excessive, need to adjust the level of protection of thyristor, to reach the object of protection thyristor, the level of protection of described dv/dt is 4～6kV/us, protection strategy is when the dv/dt of thyristor is less than level of protection, the overvoltage protection level of thyristor is constant, for 5kV～8kV, according to the design parameter of thyristor, set, when the voltage on thyristor is greater than level of protection, the overvoltage protection value of thyristor will be reduced to below 4kV.