阅读说明：本技术 一种电子开关可控自恢复电路的阻抗匹配装置 (Impedance matching device of electronic switch controllable self-recovery circuit ) 是由 胡四全 董朝阳 王蓉东 马俊杰 陈同浩 张锐 王佳佳 樊大帅 樊宏伟 冉贤贤 邹 于 2021-07-27 设计创作，主要内容包括：本发明涉及一种电子开关可控自恢复电路的阻抗匹配装置,包括连接于高压直流正负母线之间的避雷器模块和开关模块,以及阻抗匹配模块,以实现电子开关可控自恢复电路的阻抗匹配,并给出了该阻抗匹配模块的取值条件。本发明提供的电子开关可控自恢复电路的阻抗匹配装置,通过该阻抗匹配装置的电路结构设计,实现了电子开关可控自恢复电路的阻抗匹配,解决了避雷器受控元件因与电子开关及其阻尼回路并联时造成的荷电率下降,进而导致避雷器固定元件荷电率提高而降低电路整体寿命的额外难题,提高了避雷器受控元件的承压比,也提高了避雷器固定元件的使用寿命,同时解决了晶闸管触发开关晶闸管级取能的问题。(The invention relates to an impedance matching device of a controllable self-recovery circuit of an electronic switch, which comprises an arrester module, a switch module and an impedance matching module, wherein the arrester module and the switch module are connected between a high-voltage direct current positive bus and a high-voltage direct current negative bus, so that the impedance matching of the controllable self-recovery circuit of the electronic switch is realized, and the value taking condition of the impedance matching module is given. The impedance matching device of the electronic switch controllable self-recovery circuit provided by the invention realizes the impedance matching of the electronic switch controllable self-recovery circuit through the circuit structure design of the impedance matching device, solves the additional problem that the charging rate of the lightning arrester fixed element is increased and the whole service life of the circuit is shortened due to the decrease of the charging rate of the lightning arrester controlled element when the lightning arrester controlled element is connected with the electronic switch and the damping loop thereof in parallel, improves the bearing ratio of the lightning arrester controlled element, also prolongs the service life of the lightning arrester fixed element, and simultaneously solves the problem of thyristor-level energy taking of the thyristor trigger switch.)

1. An impedance matching device of a controllable self-recovery circuit of an electronic switch is characterized by comprising an arrester module and a switch module which are connected between a high-voltage direct current positive bus and a high-voltage direct current negative bus;

the lightning arrester module comprises a fixed element unit and a controlled element unit;

the switch module is connected with the controlled element unit in parallel and is controlled to be switched on or off so as to carry out switching operation on the controlled element unit;

the impedance matching module is connected to two ends of the fixed element unit in parallel to realize impedance matching.

2. The apparatus according to claim 1, wherein the fixed element unit comprises an m-class series-connected arrester group having an equivalent impedance of R_g。

3. The apparatus according to claim 2, wherein the controlled element unit comprises n-stage series-connected arrester groups having an equivalent impedance of R_c。

4. The apparatus of claim 3, wherein the switch module comprises an electronic switch unit, a mechanical switch unit, and a bypass switch unit.

5. The apparatus of claim 4, wherein the electronic switching unit, the mechanical switching unit, and the bypass switching unit are connected in parallel with each other.

6. The apparatus of claim 5, wherein the electronic switching unit comprises j stages of electronic switches connected in series with each other.

7. The apparatus of claim 6, wherein the electronic switch comprises a thyristor-triggered switch.

8. The apparatus of claim 7, wherein the impedance matching module has a resistance value R₁The following conditions are satisfied:

R₁/R_D＝R_g/R_c

wherein R is_DIs the equivalent impedance of the switch module.

9. The apparatus of claim 8, wherein the impedance matching module has a resistance value R₁The following conditions are satisfied:

(m(1+P₁₁)/(n(1-P₁₂))-P₃)*R₂*j*(1+P₂)≤R₁≤(m(1-P₁₁)/(n(1+P₁₂))+P₃)*R₂*j*(1-P₂)

wherein, P₁₁For the purpose of fixing the non-uniform voltage coefficient, P, of the arrester group₁₂For the uneven voltage coefficient, R, of the arrester group of the controlled element₂Is the impedance of a single-stage electronic switch of an electronic switching unit, P₂Is a deviation limit value, P, of a single-stage electronic switch of an electronic switch unit₃The impedance matching error of the lightning arrester module and the switch module.

Technical Field

The invention relates to the technical field of electrical equipment of an electric power system, in particular to an impedance matching device of a controllable self-recovery circuit of an electronic switch.

Background

In an extra-high voltage direct current transmission system, the saturation characteristic of air gap operation impulse discharge voltage is more obvious, and the deep reduction of the operation overvoltage level plays a vital role in reducing the air gap of a line. When the operating overvoltage is reduced from 1.7pu to 1.6pu, the air gap of the transmission line is reduced by 0.6m on average. In addition, the operation overvoltage level also has a certain influence on the manufacturing difficulty of the power transmission and transformation equipment, so that it is necessary to reduce the operation overvoltage multiple deeply.

At present, 2 schemes are mainly adopted for reducing the operation overvoltage: the 2 measures of the metal oxide arrester and the breaker additionally provided with the closing resistor are jointly used. The two combined actions can limit the maximum relative 2% statistical operation overvoltage of the system to 1.6-1.7 pu. However, the closing resistor still has great defects in the aspects of operational reliability and economy, a mechanism is complex after the closing resistor is added to the circuit breaker, the operational risk of the circuit breaker is greatly increased, the cost of the circuit breaker is increased more after the closing resistor is added to the circuit breaker, and the circuit breaker does not adopt the closing resistor when the system conditions allow the circuit breaker to be operated by power system operation departments and manufacturers.

When the line between 2 extra-high voltage transformer substations is short, the rated voltage of the lightning arrester is reduced, and the system operation overvoltage can be limited to 1.6-1.7 pu. For example, when the extra-high voltage alternating current transmission line is 60km, if a breaker is not used and a closing resistor is not used, only a metal oxide arrester is used, the rated voltage of the metal oxide arrester needs to be reduced from the current 828kV to 804kV (namely, the rated voltage is reduced by 3%), and the chargeability of the arrester is increased from the current 0.77 to 0.79. However, the longer line can not meet the requirement even if the rated voltage of the lightning arrester is reduced to 804 kV. For example, when the length of the extra-high voltage alternating current transmission line is 85.5km, the lightning arrester with 804kV can only reduce the overvoltage along the line to 1.74pu, and still cannot meet the requirement, and the rated voltage of the lightning arrester must be reduced to be lower, even 762kV (namely, the rated voltage is reduced by 8%) to meet the requirement. At the moment, the long-term operation chargeability of the lightning arrester is increased from the current 0.77 to 0.83, so that the aging speed of the lightning arrester resistance card under the normal operation condition is accelerated, and the reliability margin is greatly reduced. Moreover, the premise condition of using the 762kV lightning arrester is that the power frequency of the system is over-voltage on the bus side 1.2pu and the line side 1.3pu, so that the use condition is extremely limited.

Disclosure of Invention

Based on the above situation in the prior art, an object of the present invention is to provide an impedance matching device for a controllable self-recovery circuit of an electronic switch, which realizes impedance matching of the controllable self-recovery circuit of the electronic switch through a circuit structure design of the impedance matching device, improves a bearing ratio of a controlled element, further improves a service life of a fixed element, and solves a problem of thyristor-level energy extraction of a thyristor trigger switch.

In order to achieve the aim, the invention provides an impedance matching device of an electronic switch controllable self-recovery circuit, which comprises an arrester module and a switch module, wherein the arrester module and the switch module are connected between a high-voltage direct-current positive bus and a high-voltage direct-current negative bus;

the lightning arrester module comprises a fixed element unit and a controlled element unit;

the switch module is connected with the controlled element unit in parallel and is controlled to be switched on or off so as to carry out switching operation on the controlled element unit;

the impedance matching module is connected to two ends of the fixed element unit in parallel to realize impedance matching.

Further, the fixed element unit includes m-stage series-connected arrester groups having an equivalent impedance of R_g。

Further, the controlled element unit includes n-stage series-connected arrester groups having an equivalent impedance of R_c。

Further, the switch module includes an electronic switch unit, a mechanical switch unit, and a bypass switch unit.

Further, the electronic switch unit, the mechanical switch unit and the bypass switch unit are connected in parallel with each other.

Further, the electronic switch unit comprises j stages of electronic switches which are connected in series with each other.

Further, the electronic switch comprises a thyristor-triggered switch.

Further, the resistance value R of the impedance matching module₁The following conditions are satisfied:

R₁/R_D＝R_g/R_c

wherein R is_DIs the equivalent impedance of the switch module.

Further, the resistance value R of the impedance matching module₁The following conditions are satisfied:

(m(1+P₁₁)/(n(1-P₁₂))-P₃)*R₂*j*(1+P₂)≤R₁≤(m(1-P₁₁)/(n(1+P₁₂))+P₃)*R₂*j*(1-P₂)

wherein, P₁₁For the purpose of fixing the non-uniform voltage coefficient, P, of the arrester group₁₂For the uneven voltage coefficient, R, of the arrester group of the controlled element₂Is the impedance of a single-stage electronic switch of an electronic switching unit, P₂Is a deviation limit value, P, of a single-stage electronic switch of an electronic switch unit₃The impedance matching error of the lightning arrester module and the switch module. In summary, the present invention provides an impedance matching device for a controllable self-recovery circuit of an electronic switch, which includes an arrester module, a switch module and an impedance matching module, wherein the arrester module and the switch module are connected between a positive bus and a negative bus of a high voltage direct current, so as to implement impedance matching of the controllable self-recovery circuit of the electronic switch, and provide a value condition of the impedance matching module. The impedance matching device of the electronic switch controllable self-recovery circuit provided by the invention realizes the impedance matching of the electronic switch controllable self-recovery circuit through the circuit structure design of the impedance matching device, solves the additional problem that the charging rate of the lightning arrester fixed element is increased and the whole service life of the circuit is shortened due to the decrease of the charging rate of the lightning arrester controlled element when the lightning arrester controlled element is connected with the electronic switch and the damping loop thereof in parallel, improves the bearing ratio of the lightning arrester controlled element, also prolongs the service life of the lightning arrester fixed element, and simultaneously solves the problem of thyristor-level energy taking of the thyristor trigger switch.

Drawings

Fig. 1 is a schematic circuit diagram of an impedance matching device of an electronic switch controllable self-recovery circuit according to the invention;

FIG. 2 is a schematic diagram of a circuit configuration of an impedance matching model;

FIG. 3 is a graph of leakage current versus temperature for the 8500V/5500A thyristor at different voltages.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

The technical solution of the present invention will be described in detail below with reference to the accompanying drawings. According to an embodiment of the invention, an impedance matching device of an electronic switch controllable self-recovery circuit is provided, the circuit schematic diagram of the device is shown in fig. 1, and the device comprises an arrester module and a switch module which are connected between a high-voltage direct current positive bus and a high-voltage direct current negative bus. The lightning arrester module comprises a fixed element unit M1 and a controlled element unit M2, wherein the fixed element unit M1 and the controlled element unit M2 are connected in series, one end of the fixed element unit M1 is connected to a positive bus, the other end of the fixed element unit M1 is connected to one end of the controlled element unit M2, and the other end of the controlled element unit M2 is connected to a negative bus. The fixed element unit M1 may for example comprise an M-class series connected arrester group with an equivalent impedance R_g(ii) a The controlled element unit M2 may for example comprise an n-stage series connected arrester group with an equivalent impedance R_cAnd a natural number switch module, in which M and n are both 1 or more, is connected in parallel to the controlled element unit M2, and the switch module is turned on or off, for example, by receiving a control signal of a control system to perform a switching operation on the controlled element unit M2. The switch module comprises an electronic switch unit, a mechanical switch unit and a bypass switch unit, wherein the electronic switch unit, the mechanical switch unit and the bypass switch unit are connected in parallel. The electronic switch unit may include j stages of electronic switches connected in series, j being a natural number equal to or greater than 1, and may be determined according to an actual voltage level, for example. The electronic switch may be, for example, a thyristor-triggered switch VT. The electronic switch also includes a damping circuit, such as resistors R and C1, connected in parallel therewith.

When the system runs in a steady state, the thyristor trigger switch, the quick mechanical switch and the bypass switch in the switch module are in a brake-off state, and at the moment, the chargeability of the controlled lightning arrester element is reduced due to the fact that the controlled lightning arrester element is connected with the thyristor and the damping loop in parallel, and the chargeability of the fixed lightning arrester element is causedThe whole service life of the energy dissipation device is prolonged and reduced. The impedance matching can improve the chargeability of the lightning arrester fixing element, and in order to solve the impedance matching problem, according to the embodiment of the invention, the impedance matching module is connected in parallel at the two ends of the lightning arrester fixing element unit M1 to realize impedance matching so as to ensure that the static voltage division relation of the lightning arrester cannot be influenced by the parameters of the thyristor trigger switch. Resistance R of the impedance matching module₁The following conditions should be satisfied:

R₁/R_D＝R_g/R_c

wherein R is_DIs the equivalent impedance of the switch module.

In order to confirm the specific parameters of the impedance matching module, the impedance ratio between the fixed element unit M1 and the controlled element unit M2 in the arrester circuit and the impedance characteristics of the thyristor trigger switch need to be analyzed and calculated, and the schematic circuit structure diagram of the impedance matching model is shown in fig. 2.

Setting the uneven voltage coefficient of the fixed element arrester group as P₁₁The uneven voltage coefficient of the controlled element lightning arrester group is P₁₂The impedance ratio of the fixed element unit M1 to the controlled element unit M2 is K_m＝R_g/R_cThen, there are:

m(1-P₁₁)/(n(1+P₁₂))≤K_m≤m(1+P₁₁)/(n(1-P₁₂)) (1)

let R_DIs the equivalent impedance of the switch module. In the off state, the impedance of the mechanical switch unit and the bypass switch unit is much larger than the impedance of the electronic switch, and R is larger than R_DThe value of (A) can be directly used as the impedance of an electronic switch, wherein the electronic switch is formed by connecting j stages of electronic module units in series, and the impedance of a single-stage module of the electronic switch is R₂Deviation limit P₂Then, there are:

R₂*j*(1-P₂)≤R_D≤R₂*j*(1+P₂) (2)

impedance ratio of the switch module:

K_d＝R₁/R_D (3)

impedance matching error limit for lightning arrester module and switch moduleValue of P₃Then, there are:

|K_d-K_m|≤P₃

it can be derived that:

K_m-P₃≤K_d≤K_m+P₃ (4)

if R is₁The value range of (1) is that min is less than or equal to R₁Max, as can be derived from the formulae (2), (3) and (4):

min/(R₂*j*(1+P₂))≥K_m-P₃

max/(R₂*j*(1-P₂))≥K_m+P₃

then

min≥(K_m-P₃)*R₂*j*(1+P₂) (5)

max≤(K_m+P₃)*R₂*j*(1-P₂) (6)

The impedance range of R1 can be obtained from the formulas (1), (5) and (1), (6)

(m(1+P₁₁)/(n(1-P₁₂))-P₃)*R₂*j*(1+P₂)≤R₁≤(m(1-P₁₁)/(n(1+P₁₂))+P₃)*R₂*j*(1-P₂)

Wherein, P₁₁For the purpose of fixing the non-uniform voltage coefficient, P, of the arrester group₁₂For the uneven voltage coefficient, R, of the arrester group of the controlled element₂Is the impedance of a single-stage electronic switch of an electronic switching unit, P₂Is a deviation limit value, P, of a single-stage electronic switch of an electronic switch unit₃The impedance matching error of the lightning arrester module and the switch module.

The following is a further description of a specific embodiment. In this embodiment, the resistance sheet of the surge arrester fixing element unit M1 is 88 series connection sheets, the resistance sheet of the surge arrester controlled element unit M2 is 19 series connection sheets, and the impedance ratio of the fixing element unit M1 to the controlled element unit M2 is 4.63. The electronic switch unit is formed by connecting 24-level thyristors in series, the thyristor trigger switch adopts a 8500V/5500A thyristor, and the direct-current voltage-sharing resistor R2 is 300k omega. The relationship curve of the leakage current of the 8500V/5500A thyristor under different voltages and the temperature is shown in figure 3, the voltage of the thyristor is 3.675kV for calculation, and the typical off-state impedance is shown in table 1.

TABLE 1

Ambient temperature	Single stage thyristor impedance
		20℃	50MΩ
40℃	20MΩ
		50℃	8MΩ

The thyristor trigger switch direct current equalizing resistor R2 is 300k omega, the impedance of the thyristor in an off state is far larger than the direct current equalizing resistor R2, and the impedance of the RC damping loop in direct current is also far larger than 300k omega of the direct current equalizing resistor, so that the equivalent impedance of the thyristor trigger switch in the off state is 300k omega multiplied by 24 which is 7.2M omega.

Therefore, to maintain the voltage ratio between the fixed element unit M1 and the controlled element unit M2 at about 4.63, the resistance R of the impedance matching module is maintained₁And was 33.3M omega. Setting P considering uneven voltage coefficient of lightning arrester₁＝0.001，R₂Deviation limit value P of₂0.002, limit value of impedance matching error of lightning arrester module and switch module₃When R is 0.05, then₁The value range is as follows:

33.12MΩ≤R₁≤33.57MΩ。

in summary, the present invention relates to an impedance matching device of an electronic switch controllable self-recovery circuit, which includes an arrester module, a switch module and an impedance matching module, wherein the arrester module and the switch module are connected between a high-voltage direct current positive bus and a high-voltage direct current negative bus, so as to implement impedance matching of the electronic switch controllable self-recovery circuit, and provide a value taking condition of the impedance matching module. The impedance matching device of the electronic switch controllable self-recovery circuit provided by the invention realizes the impedance matching of the electronic switch controllable self-recovery circuit through the circuit structure design of the impedance matching device, solves the additional problem that the charging rate of the lightning arrester fixed element is increased and the whole service life of the circuit is shortened due to the decrease of the charging rate of the lightning arrester controlled element when the lightning arrester controlled element is connected with the electronic switch and the damping loop thereof in parallel, improves the bearing ratio of the lightning arrester controlled element, also prolongs the service life of the lightning arrester fixed element, and simultaneously solves the problem of thyristor-level energy taking of the thyristor trigger switch.

It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.