CN114665454B - A DC lightning arrester and a lightning arrester voltage equalization method - Google Patents
A DC lightning arrester and a lightning arrester voltage equalization method Download PDFInfo
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- CN114665454B CN114665454B CN202011535971.8A CN202011535971A CN114665454B CN 114665454 B CN114665454 B CN 114665454B CN 202011535971 A CN202011535971 A CN 202011535971A CN 114665454 B CN114665454 B CN 114665454B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
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Abstract
一种直流用避雷器，包括的避雷器本体，所述避雷器本体包括固定元件和受控元件，其特征在于，所述避雷器还包括：与受控元件并联的晶闸管控制开关支路；与固定元件并联的均压支路；通过调整均压支路中均压电阻的串联和/或并联数量，以实现避雷器本体中固定元件和受控元件的均压。防止避雷器固定原件稳态工况下分压较高，泄漏电流增大。
A DC lightning arrester includes an arrester body, wherein the arrester body includes a fixed element and a controlled element, and is characterized in that the arrester further includes: a thyristor-controlled switch branch connected in parallel with the controlled element; a voltage-equalizing branch connected in parallel with the fixed element; and voltage equalization of the fixed element and the controlled element in the arrester body is achieved by adjusting the number of series and/or parallel voltage-equalizing resistors in the voltage-equalizing branch. This prevents the fixed element of the arrester from having a high voltage division under steady-state conditions, thereby increasing leakage current.
Description
Technical Field
The invention relates to the field of direct current arresters for hybrid extra-high voltage direct current transmission engineering, in particular to a direct current arrester and an arrester voltage equalizing method.
Background
The high-voltage direct-current transmission technology mainly comprises traditional high-voltage direct-current transmission based on a common thyristor converter valve and flexible direct-current transmission based on a novel power electronic device converter valve with turn-off capability, and the two have advantages and disadvantages and application occasions. In order to exert the advantages of the two, a more flexible power transmission mode is provided, and a hybrid multi-terminal extra-high voltage direct current power transmission system consisting of traditional direct current and flexible direct current is generated. Along with the continuous development of hybrid multi-terminal extra-high voltage direct current transmission technology and the increasing of future planning engineering, the reliability of the hybrid multi-terminal extra-high voltage direct current transmission technology becomes an important factor affecting the safe and reliable operation of the whole power system. And considering the overvoltage condition of the mixed direct current converter valve under various temporary, steady-state and various abnormal operation conditions, the direct current side bus of the flexible direct current converter valve is connected in parallel with a direct current lightning arrester based on thyristor control.
The structural topology and the working principle of the lightning arrester can know that the lightning arrester bears direct current working voltage for a long time under the steady state, and the fixed element has higher partial pressure under the steady state working condition due to the influence of devices such as a thyristor off-state resistor, a voltage equalizing resistor and the like in the thyristor trigger switch of which the controlled elements are connected in parallel, so that the leakage current is increased, and the stability of the lightning arrester resistor sheet under the long-term working condition is further influenced.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention provides a dc lightning arrester, including a lightning arrester body, the lightning arrester body including a fixing element and a controlled element, wherein the lightning arrester further includes:
A thyristor controlled switching branch connected in parallel with the controlled element;
A voltage equalizing branch connected in parallel with the fixing element;
the voltage equalizing of the fixed element and the controlled element in the lightning arrester body is realized by adjusting the serial and/or parallel number of the voltage equalizing resistors in the voltage equalizing branch.
Preferably, the equalizing branch circuit includes:
A multi-stage series resistance structure;
each stage of resistor structure comprises a plurality of voltage equalizing resistors connected in parallel;
And the series number of the resistor structures and/or the parallel number of the voltage equalizing resistors in each stage of resistor structure are configured according to the expected resistance value of the voltage equalizing branch.
Preferably, the expected resistance value of the voltage equalizing branch is determined according to the off-state resistance value R T of the thyristor in the thyristor controlled switch branch, the voltage equalizing resistance value R p in the thyristor controlled switch branch, and the damping ratio of the fixed element to the controlled element.
Preferably, the thyristor controlled switch branch comprises:
A thyristor;
A saturable reactor connected in series with the thyristor;
And a resistance-capacitance structure and a voltage equalizing resistor connected in parallel with the thyristor.
Preferably, the lightning arrester further comprises:
a bypass switch connected in parallel with the controlled element.
Preferably, the fixed element and the controlled element each comprise a plurality of resistive patches connected in series.
Based on the same idea, the invention provides a voltage equalizing method of a direct current lightning arrester, which comprises the following steps:
When the lightning arrester is in a steady-state working condition, the thyristor is controlled to be in a disconnected state by utilizing the thyristor control switch branch, and the damping ratio of a fixed element and a controlled element in the lightning arrester body, the off-state resistance value of the thyristor in the thyristor control switch branch and the voltage-sharing resistance value of the thyristor control switch branch are obtained;
determining an expected resistance value of a voltage equalizing branch connected in parallel with the fixed element based on the damping ratio, the off-state resistance value and the resistance value of the thyristor controlled switching branch;
And the resistance value of the voltage equalizing branch circuit reaches the expected resistance value by adjusting the serial and/or parallel number of the voltage equalizing resistors in the voltage equalizing branch circuit, so that the voltage equalizing of the fixed element and the controlled element in the lightning arrester body is realized.
Preferably, the calculation formula of the expected resistance value is as follows:
Wherein R q is an expected resistance value, R T is an off-state resistance value of a thyristor in a thyristor control switch branch, R p is a voltage equalizing resistance value in the thyristor control switch branch, and m and n are the number of serially connected resistance pieces in a fixed element and a controlled element respectively.
Preferably, the adjusting the serial and/or parallel number of the equalizing resistors in the equalizing branch circuit includes:
When the off-state resistance of the thyristor is reduced, the series number of the resistance structures is reduced and/or the parallel number of the equalizing resistors in each resistance structure is increased;
Conversely, the series number of the resistor structures is increased and/or the parallel number of the equalizing resistors in each resistor structure is reduced.
Compared with the prior art, the invention has the beneficial effects that:
The lightning arrester for direct current comprises a lightning arrester body, wherein the lightning arrester body comprises a fixed element and a controlled element, and is characterized by further comprising a thyristor control switch branch connected in parallel with the controlled element, a voltage equalizing branch connected in parallel with the fixed element, and the voltage equalizing of the fixed element and the controlled element in the lightning arrester body is realized by adjusting the serial and/or parallel number of voltage equalizing resistors in the voltage equalizing branch. The lightning arrester fixing element is prevented from being higher in partial pressure and increasing in leakage current under the steady-state working condition.
Drawings
Fig. 1 is a topological structure diagram of a dc arrester;
fig. 2 is a topology diagram of the resistor Rq structure.
Detailed Description
For a better understanding of the present invention, reference is made to the following description, drawings and examples.
Example 1:
the invention provides a lightning arrester for direct current, as shown in figure 1, comprising a lightning arrester body connected in parallel on a direct current side bus of a flexible direct current converter valve, wherein the flexible direct current converter valve is connected between a direct current system and an alternating current system, the lightning arrester body comprises a fixed element and a controlled element, and is characterized in that the lightning arrester further comprises:
A thyristor controlled switching branch connected in parallel with the controlled element;
A voltage equalizing branch connected in parallel with the fixing element;
the voltage equalizing of the fixed element and the controlled element in the lightning arrester body is realized by adjusting the serial and/or parallel number of the voltage equalizing resistors in the voltage equalizing branch.
When the lightning arrester is in a steady-state working condition, the thyristor is controlled to be in a disconnected state (short for disconnection state) through the thyristor control switch branch, and when the flexible direct current converter valve, the direct current system and/or the alternating current system are/is in faults, the thyristor is controlled to be switched on through the thyristor control switch branch, so that the fault current is shunted.
Preferably, the equalizing branch circuit includes:
A multi-stage series resistance structure;
each stage of resistor structure comprises a plurality of voltage equalizing resistors connected in parallel;
the series number of the resistor structures shown in fig. 2 and/or the parallel number of the equalizing resistors in each stage of the resistor structures are configured according to the expected resistance values of the equalizing branches.
Preferably, the expected resistance value of the voltage equalizing branch is determined according to the off-state resistance value of the thyristor in the thyristor controlled switch branch, the voltage equalizing resistance value in the thyristor controlled switch branch, and the damping ratio of the fixed element to the controlled element.
Preferably, the thyristor controlled switch branch comprises:
a thyristor, a resistance-capacitance structure connected with the thyristor in parallel and a equalizing resistor.
Preferably, the thyristor controlled switch branch further comprises:
A bypass switch connected in parallel with the thyristor;
When the lightning arrester is in a steady-state working condition, the bypass switch is controlled to be in an off state (in short for off state), and when the flexible direct current converter valve, the direct current system and/or the alternating current system are/is in fault, the bypass switch is controlled to be switched on so as to realize further current diversion of fault current;
preferably, the fixed element and the controlled element each comprise a plurality of resistive patches connected in series.
Example 2:
based on the same inventive concept, the invention also provides a lightning arrester voltage equalizing method, which comprises the following steps:
Obtaining a damping ratio of a fixed element and a controlled element in a lightning arrester body, an off-state resistance value of a thyristor in a thyristor control switch branch and a resistance value of the thyristor control switch branch;
determining an expected resistance value of a voltage equalizing branch connected in parallel with the fixed element based on the damping ratio, the off-state resistance value and the resistance value of the thyristor controlled switching branch;
And the resistance value of the voltage equalizing branch circuit reaches the expected resistance value by adjusting the serial and/or parallel number of the voltage equalizing resistors in the voltage equalizing branch circuit, so that the voltage equalizing of the fixed element and the controlled element in the lightning arrester body is realized.
Preferably, the calculation formula of the expected resistance value is as follows:
Wherein R q is an expected resistance value, R T is an off-state resistance value of a thyristor in a thyristor control switch branch, R p is a voltage equalizing resistance value in the thyristor control switch branch, and m and n are the number of serially connected resistance pieces in a fixed element and a controlled element respectively.
Preferably, the adjusting the serial and/or parallel number of the equalizing resistors in the equalizing branch circuit includes:
When the off-state resistance of the thyristor is reduced, the series number of the resistance structures is reduced and/or the parallel number of the equalizing resistors in each resistance structure is increased;
Conversely, the series number of the resistor structures is increased and/or the parallel number of the equalizing resistors in each resistor structure is reduced.
Example 3:
The lightning arrester belongs to a typical high-capacity multi-column parallel lightning arrester, and the residual voltage is changed by controlling the serial number of the resistor discs so as to limit the bus overvoltage under different system faults. The primary side of the arrester mainly comprises a fixed element, a controlled element and a control switch (comprising a thyristor trigger switch and a bypass switch), wherein the fixed element and the controlled element are also called an arrester body. When the system has AC/DC fault, the controlled elements are connected in parallel to reduce residual voltage, consume surplus power, inhibit overvoltage of bus in parallel, control the switch to switch off and restore the arrester to initial state.
The metal oxide resistor sheet is charged for a long period of time during normal operation, and gradually ages, and even eventually causes thermal breakdown, which is a major factor in determining the life of the arrester. Aging presents a speed problem, depending on the operating voltage of the system that acts for a long time, and on the long-term charge of the resistor, which must be limited in order to guarantee the life of the resistor. The chargeability refers to the ratio λ of the long-term operating voltage peak to the operating voltage.
The lightning arrester topology is shown in figure 1, wherein MOA1 comprises a fixed element, MOA2 comprises a controlled element, K1 comprises a thyristor trigger switch, K2 comprises a bypass switch, T comprises a thyristor, lv comprises a saturation reactor, R D comprises a damping resistor, C D comprises a damping capacitor and R p comprises a equalizing resistor.
1. Design principle
The known arrester is connected in parallel to the bus side of a direct current system converter valve, and the fixed element working voltage U1, the controlled element voltage U2 and the bus working voltage Ub have the following voltage relationship:
U1+U2＝Ub (1)
the partial pressures of the fixed element and the controlled element are determined by the respective series resistor numbers, the series resistor number m of the fixed element and the series resistor number n of the controlled element are set.
Wherein:
r MOV1 is the resistance value of the fixed element;
R MOV2, resistance value of controlled element.
The design principle is as follows:
λ1＝U1/Ua1＝U2/Ua2＝λ2≤λo (5)
Wherein:
Lambda 1 fixed element charge rate;
Lambda 2 controlled element charge rate;
u a1, fixing element action voltage;
U a2 controlled element operating voltage;
And lambda o, the maximum value of the charging rate of the lightning arrester.
The long-term charge rate of the lightning arrester must be lower than lambda o to ensure the stability of the metal oxide.
2. Partial pressure optimization method
As can be seen from fig. 1, the controlled elements need to be connected in parallel to control the switch. K2 is a bypass switch, is open under steady-state working condition, and has no influence on the partial pressure of the lightning arrester body element. K1 is a thyristor trigger switch, under steady-state direct current voltage, the thyristor T is not conducted, works in an off state for a long time, externally shows a high resistance state, the external characteristics of a damping capacitor C D and a damping resistor R D branch are off, and a voltage equalizing resistor R p is a direct current resistor, so that the steady-state direct current voltage division of the lightning arrester can be influenced by the off-state resistor R T and the voltage equalizing resistor R p of the thyristor T.
When K1 is present, the arrester securing element operating voltage U 1 'and the controlled element operating voltage U 2' are provided as follows.
Is known to be
Thus (2)
U1′＞U1 (9)
When K1 is present, the fixation element partial pressure increases and lambda 1 increases.
To reduce the steady state charge rate of the fixed portion, a resistor R q is connected in parallel to the fixed element, as shown in the topology of fig. 1.In order to reduce the voltage division effect caused by K1 as much as possible, the resistance value of the resistor R q needs to be matched with the equalizing resistor R p according to the off-state resistor R T of the thyristor, and the following relation exists.
Thus there is the following derivation:
Substituting the formulas (2) and (11) into the formula (12) to obtain
The resistor R q reduces the influence of steady-state voltage division of the lightning arrester caused by the introduction of the control switch, and reduces the steady-state charge rate of the fixed element.
3. Resistor Rq resistance value adjusting design
Thyristors are nonlinear elements, the off-state resistance does not change substantially when the ambient temperature is below a certain value, and the resistance becomes small or even decreases from megaohms to kiloohms when the ambient temperature is above a certain value. In order to ensure the charging rate of the lightning arrester element at any ring temperature, the patent proposes a method for reducing the influence caused by nonlinear characteristics of the off-state resistance of the thyristor by adjusting the resistance value of R q.
Resistor R q has a device series-parallel design as in FIG. 2, and is composed of a-stage parallel b-stage series resistors. When the lightning arrester runs in a steady state, when the ring temperature is higher than a certain value due to special conditions, the off-state resistance of the thyristor is reduced, the parallel number a of the resistor device is increased or the series number b is reduced to reduce the resistance value of the resistor R q for matching, otherwise, the resistance value is increased, and therefore the influence of K1 on the charging rate of the lightning arrester is reduced as much as possible.
It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof, but rather as providing for the use of additional embodiments and advantages of all such modifications, equivalents, improvements and similar to the present invention are intended to be included within the scope of the present invention as defined by the appended claims.
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| CN214543612U (en) * | 2020-12-23 | 2021-10-29 | 全球能源互联网研究院有限公司 | Lightning arrester for direct current |
| CN113612469A (en) * | 2021-07-27 | 2021-11-05 | 许继集团有限公司 | Impedance matching device of electronic switch controllable self-recovery circuit |
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| US6459559B1 (en) * | 1999-01-14 | 2002-10-01 | Dale Jack Christofersen | Thyristor controlled dynamic voltage suppressor for electric power systems |
| CN101639507B (en) * | 2009-07-16 | 2012-06-13 | 中国电力科学研究院 | Controllable metal oxide arrester action characteristic testing device and method therefor |
| CN101916309B (en) * | 2010-07-29 | 2012-11-28 | 中国电力科学研究院 | Design method for electric performance of saturable reactor for converter valve |
| CN103176117B (en) * | 2013-02-27 | 2016-01-20 | 国网智能电网研究院 | A kind of high-power thyristor turn-off characteristic test device based on half-wave method |
| US10447026B2 (en) * | 2016-12-23 | 2019-10-15 | Ripd Ip Development Ltd | Devices for active overvoltage protection |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN214543612U (en) * | 2020-12-23 | 2021-10-29 | 全球能源互联网研究院有限公司 | Lightning arrester for direct current |
| CN113612469A (en) * | 2021-07-27 | 2021-11-05 | 许继集团有限公司 | Impedance matching device of electronic switch controllable self-recovery circuit |
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