CN102231569B - Control protection system and method for metal oxide varistor (MOV) branch circuit - Google Patents

Abstract

The invention discloses a control protection system and a control protection method for a flexible AC power transmission device, and relates to the field of control protection of the flexible AC power transmission device. The control protection system comprises a data acquisition device and a control protection device. The data acquisition device collects measurement signals of two or more measurement current transformers (CT) of the MOV branch circuit, and transmits the measurement signals of the two or more measurement CTs to the control protection device. The control protection device performs consistency judgment on the measurement signals of the two or more measurement CTs, and protects the measurement signals as credible measurement signals if the measurement signals are consistent. By the control protection system and the control protection method for the MOV branch circuit, the reliability of a control protection function of a series compensation device/fault current limiter device is improved, and the unnecessary out of service of the device caused by the false protection operations of the series compensation device can be prevented, thereby remarkably increasing the availability and utilization rate of the whole device.

Description

Control protection system and the method for MOV branch road

Technical field

The present invention relates to the control protection field of flexible AC transmission device, relate in particular to control protection system and the method for MOV branch road.

Background technology

The series capacitor compensation technology of AC transmission system (being called for short string mends) is that power capacitor is series in transmission line of alternation current, the part emotional resistance of compensation transmission line of alternation current, thus reach purposes such as increasing circuit transmission capacity, the raising stability of a system, the network loss that reduces, saving investment.In remote, large capacity transmission system, increase along with transmission distance, its conveying capacity is subject to increasing restriction, and the string benefit is one of important means addressed this problem, improve ultra-high/extra-high voltage transmission line ability of supplying electric power, there is very huge economic worth, received at present application widely in the electric power system of countries in the world.

Thyristor controlled series capacitor compensation arrangement (abbreviation controlled series compensation) is regulated the equivalent impedance of fundamental frequency of controlled series compensation by the Trigger Angle that changes thyristor, the dynamic control of realization to equivalent impedance of fundamental frequency, thereby can further improve stability of power system, increase the transmission capacity of transmission line, suppress low-frequency oscillation of electric power system and subsynchronous resonance.When the ultra-high/extra-high voltage transmission line is short-circuited fault, controlled series compensation proceeds to thyristor bypass series capacitor pattern immediately, can reduce the short circuit current of system, improves the stability of electric power system.

Developing rapidly of electric power system, the load in unit and station capacity, substation capacity, city and the center of industry and the continuation of load density increase, and interconnected between electric power system, cause the short circuit current level in modern large power system electrical networks at different levels constantly to increase.Short circuit current exceeds standard becomes one of major issue that threatens the modern power systems safe operation.Except changing electric network composition, the series resonant-type fault current limiter device is to solve short circuit current exceed standard new approaches and the new way of problem.2009, the superhigh pressure fault current limiter device was at East China Power Grid 500kV bottle kiln electric substation hanging net operation, and this device is in the stage of applying.

Fixed series capacitors compensation arrangement, thyristor controlled series capacitor compensation arrangement, series resonant-type fault current limiter device etc. have the control protection system.The Main Function of controlling protection system is: detect in service various to installing disadvantageous failure condition, the relevant protection of correct operation, isolated fault timely and accurately, the safe and stable operation of assurance device, and coordinate route protection to carry out the miscellaneous equipment in protection system.In addition, control protection system also there is electrical quantities measurement and gather, the functions such as monitoring running state, record ripple, man-machine interaction.In station, should be able to realize should be able to realizing the supervision to key equipment state to supervision and the control of all key equipment states such as bypass breaker, isolating switch, grounding switch by telecontrol equipment in dispatching office.

At present, the control protection system that string is mended device is comprised of the two independently systems of overlapping usually, and two cover systems configurations are identical, independently is measured separately, data collection and control protects.When a cover system need to be overhauled or due to other reasons when out of service, what another set of system still can be stable works on, guarantee that string mends the normal operation of device.Two Redundant Control protection system outlet logic one be generally or relation, as long as one of them system meets corresponding operation condition, protection will trigger.

At present, the possibility of the protection malfunction of control protection system is larger.

Summary of the invention

In view of this, the technical problem that the present invention will solve is to provide a kind of control protection system of MOV branch road, can improve the reliability of controlling defencive function.

A kind of control protection system of flexible AC transmission device, described control protection system comprises data acquisition unit, control protective unit; Described data acquisition unit is collected the measuring-signal of two or more measurements CT that is arranged on metal oxide pressure-limiting device MOV branch road, and the described measuring-signal that two or more measure CT is sent to described control protective unit; Described control protective unit carries out the consistency judgement to the described measuring-signal that two or more measure CT, if meet the consistency judgement carry out conservation treatment as credible measuring-signal.

An embodiment of system according to the invention; described control protective unit carries out the consistency judgement to the described measuring-signal that two or more measure CT and comprises: described control protective unit judge whether the difference between the measuring-signal of described two or more measurements CT is less than or equal to predetermined threshold; if be less than or equal to predetermined threshold, meet the consistency judgement.

An embodiment of system according to the invention, described control protective unit comprises data summarization unit, consistency judging unit, protected location; Wherein, described data summarization unit receives described two or more and measures the measuring-signal of CT, and the described measuring-signal that two or more measure CT is sent to the consistency judging unit; Described consistency judging unit carries out the consistency judgement to two or more measuring-signals of measuring CT of metal oxide pressure-limiting device MOV branch road, and the believable measuring-signal that meets the consistency judgement is sent to described protected location; Described protected location receives described believable measuring-signal, carries out protection algorithm and control strategy, the output protection action command.

An embodiment of system according to the invention, be provided with two at metal oxide pressure-limiting device MOV branch road and measure CT; Described consistency judging unit carries out the consistency judgement to described two measuring-signals of measuring CT, is specially: described two the measuring-signal i that measure CT of described consistency judgment unit judges _mOV1and i _mOV2whether meet:

|i _MOV1-i _MOV2|≤Δi；

Perhaps, described two the measuring-signal i that measure CT of described consistency judgment unit judges _mOV1and i _mOV2whether meet:

$\frac{|i_{\mathrm{MOV}2}-i_{\mathrm{MOV}1}|}{\left|i_{\mathrm{MOV}1}\right|+\left|i_{\mathrm{MOV}2}\right|}\≤\mathrm{\δ}\%;$

Perhaps, if i _mOV1and i _mOV2be worth larger, described two the measuring-signal i that measure CT of described consistency judgment unit judges _mOV1and i _mOV2whether meet:

|i _MOV1-i _MOV2|≤Δi；

If i _mOV1and i _mOV2be worth less, described two the measuring-signal i that measure CT of described consistency judgment unit judges _mOV1and i _mOV2whether meet:

$\frac{|i_{\mathrm{MOV}2}-I_{\mathrm{MOV}1}|}{\left|i_{\mathrm{MOV}1}\right|+\left|i_{\mathrm{MOV}2}\right|}\≤\mathrm{\δ}\%;$

I wherein _mOV1and i _mOV2be respectively two measurement current values of measuring CT that arrange at metal oxide pressure-limiting device MOV branch road, Δ i and δ % are judgment threshold,

If meet, meet the consistency judgement.

An embodiment of system according to the invention, described metal oxide pressure-limiting device MOV branch road comprises MOVA branch road in parallel and MOVB branch road, MOVA branch road and MOVB branch road are respectively arranged with two and measure CT, wherein i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road; Described control protective unit also comprises the measuring-signal selected cell; If determine and do not meet consistency checking when the consistency judging unit, described measuring-signal selected cell is used for: if branch road MOVA and MOVB are even configurations, by i _mOVA1and i _mOVA2respectively with the i of MOVB branch road _mOVB1and i _mOVB2mean value compare, judge i _mOVA1and i _mOVA2what difference was larger is undesired signal; Perhaps, if branch road MOVA and MOVB are by certain proportional arrangement, according to i in the MOVB branch road _mOVB1and i _mOVB2mean value, calculate current value i in the MOVA branch road by allocation ratio _mOVA0; By i _mOVA1and i _mOVA2respectively with i _mOVA0compare, judge i _mOVA1and i _mOVA2what difference was larger is undesired signal.

An embodiment of system according to the invention, described metal oxide pressure-limiting device MOV branch road is applied to string and mends in device or fault current limiter, described string is mended in device or fault current limiter bypass breaker is set, described metal oxide pressure-limiting device MOV branch road comprises MOVA branch road in parallel and MOVB branch road, the MOVA branch road is provided with two and measures CT, wherein i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road; Described control protective unit also comprises the measuring-signal selected cell; If do not meet consistency checking, described control protective unit also for: during in open mode, the current value of MOVB branch road is fixed as to i when described bypass breaker _mOVB1or i _mOVB2, inflow current is converged to the algebraic value of all electric currents of node A and carry out read group total, wherein the current value of MOVA branch road is got respectively two current i of measuring CT _mOVA1and i _mOVA2, select i _mOVA1and i _mOVA2in make described read group total result absolute value closer to 0 current value, be believable measuring-signal; Wherein, described electric current converges node A and is arranged in the lumped-circuit that comprises described metal oxide pressure-limiting device MOV branch road, and makes electric current on described MOVA branch road and MOVB branch road can both flow into described electric current to converge node A.

An embodiment of system according to the invention, described measuring-signal selected cell and consistency judging unit are deployed in described protected location, or described measuring-signal selected cell and consistency judging unit are deployed in described data summarization unit.

An embodiment of system according to the invention, described system is mended device or fault current limiter for going here and there; Described string is mended device and fault current limiter comprises: fixed series capacitors compensation arrangement, thyristor controlled series capacitor compensation arrangement, series resonant-type fault current limiter device.

System of the present invention has adopted Redundancy Design to the measurement CT of MOV branch road; two or more current signals of measuring CT to same MOV branch road carry out the consistency judgement; carry out conservation treatment as credible measuring-signal when meeting the consistency judgement; effectively prevent the generation of protection misoperation, improved the reliability of controlling defencive function.

Another technical problem that the present invention will solve is to provide a kind of control guard method of MOV branch road, can control the reliability of defencive function.

According to an aspect of the present invention, provide a kind of control guard method of flexible AC transmission device, collect the measuring-signal of two or more measurements CT that is arranged on metal oxide pressure-limiting device MOV branch road; The described measuring-signal that two or more measure CT is carried out to the consistency judgement, if meet the consistency judgement carry out conservation treatment as credible measuring-signal.

The embodiment according to the inventive method, describedly the described measuring-signal that two or more measure CT is carried out to the consistency judgement comprise: judge whether the described difference that two or more are measured between the measuring-signal of CT is less than or equal to predetermined threshold, if be less than or equal to predetermined threshold, meet the consistency judgement.

According to an embodiment of the inventive method, described device comprises metal oxide pressure-limiting device MOV branch road in parallel, and each described metal oxide pressure-limiting device MOV branch road configures respectively two or more and measures CT; Collect the measuring-signal of two or more measurements CT of each metal oxide pressure-limiting device MOV branch road; Two or more measuring-signals of measuring CT to each metal oxide pressure-limiting device MOV branch road carry out the consistency judgement, if meet the consistency judgement processed as credible measuring-signal.

Be provided with two at metal oxide pressure-limiting device MOV branch road and measure CT; Described two measuring-signals of measuring CT are carried out to the consistency judgement, are specially:

Judge whether to meet:

|i _MOV1-i _MOV2|≤Δi；

Perhaps,

Judge whether to meet:

$\frac{|i_{\mathrm{MOV}2}-i_{\mathrm{MOV}1}|}{\left|i_{\mathrm{MOV}1}\right|+\left|i_{\mathrm{MOV}2}\right|}\≤\mathrm{\δ}\%;$

Perhaps,

If i _mOV1and i _mOV2be worth larger, the judgement i _mOV1and i _mOV2whether meet:

|i _MOV1-i _MOV2|≤Δi；

If i _mOV1and i _mOV2be worth less, the judgement i _mOVA1and i _mOVA2whether meet:

$\frac{|i_{\mathrm{MOV}2}-i_{\mathrm{MOV}1}|}{\left|i_{\mathrm{MOV}1}\right|+\left|i_{\mathrm{MOV}2}\right|}\≤\mathrm{\δ}\%;$

If meet, meet the consistency judgement, wherein i _mOV1and i _mOV2be respectively two measurement current values of measuring CT that arrange at metal oxide pressure-limiting device MOV branch road, Δ i and δ % are judgment threshold.

According to an embodiment of the inventive method, described metal oxide pressure-limiting device MOV branch road comprises in parallel MOVA branch road and MOVB branch road, and MOVA branch road and MOVB branch road are respectively arranged with two and measure CT, wherein i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road; If do not meet consistency checking, carry out following judgement: if branch road MOVA and MOVB are even configurations, by i _mOVA1and i _mOVA2respectively with the M of MOVB branch road _oVB1and i _mOVB2mean value compare, what difference was larger is undesired signal; Perhaps, if branch road MOVA and MOVB are by certain proportional arrangement, according to i in the MOVB branch road _mOVB1and i _mOVB2mean value, calculate current value i in the MOVA branch road by allocation ratio _mOVA0; By i _mOVA1and i _mOVA2respectively with i _mOVA0compare, what difference was larger is undesired signal.

The embodiment according to the inventive method, described metal oxide pressure-limiting device MOV branch road is applied to string and mends in device or fault current limiter, described string is mended in device or fault current limiter bypass breaker is set, described metal oxide pressure-limiting device MOV branch road comprises MOVA branch road in parallel and MOVB branch road, the MOVA branch road is provided with two and measures CT, wherein i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road; If do not meet consistency checking, carry out following judgement: in the lumped-circuit that comprises described metal oxide pressure-limiting device MOV branch road, select electric current to converge node A, make electric current on described MOVA branch road and MOVB branch road can both flow into described electric current and converge node A; , converge the algebraic value of all electric currents of node (A) to flowing into described electric current and carry out read group total during in open mode when described bypass breaker; Wherein the current value of MOVB branch road is fixed as to i _mOVB1or i _mOVB2, and the current value of establishing the MOVA branch road is respectively i _mOVA1and i _mOVA2; At i _mOVA1and i _mOVA2in, the absolute value of selecting to make described read group total result is believable measuring-signal closer to 0 current value; Perhaps the current value of MOVA branch road is fixed as to i _mOVA1or i _mOVA2, and the current value of establishing the MOVB branch road is respectively i _mOVB1and i _mOVB2; At i _mOVB1and i _mOVB2in, the absolute value of selecting to make described read group total result is believable measuring-signal closer to 0 current value.

According to an embodiment of the inventive method, described method is mended device or fault current limiter for going here and there; Described string is mended device and fault current limiter comprises: fixed series capacitors compensation arrangement, thyristor controlled series capacitor compensation arrangement, series resonant-type fault current limiter device.

The inventive method is carried out the consistency judgement to two or more current signals of measuring CT of same MOV branch road; carry out conservation treatment as credible measuring-signal when meeting the consistency judgement; effectively prevent the generation of protection misoperation, improved the reliability of controlling defencive function.

The accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, below will the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain according to these accompanying drawings other accompanying drawing.

The string that Fig. 1 is one embodiment of the invention is mended the schematic diagram of the two CT of measurement of MOV branch road band in device;

The string that Fig. 2 is one embodiment of the invention is mended the schematic diagram of controlling protection system in device;

The schematic diagram of the control protection system that Fig. 3 is one embodiment of the invention;

The schematic diagram of the control protective unit in the control protection system that Fig. 4 A is another embodiment of the present invention;

The schematic diagram of the control protective unit in the control protection system that Fig. 4 B is another embodiment of the present invention;

The schematic diagram of the control protective unit in the control protection system that Fig. 4 C is another embodiment of the present invention;

The single-phase schematic diagram of fixed series compensation of the MOV branch road in parallel that Fig. 5 is one embodiment of the present of invention;

The two CT schematic diagrams of measuring of the MOV branch road band of the fault current limiter that Fig. 6 is one embodiment of the invention;

Fig. 7 is the flow chart according to an embodiment of the control guard method of flexible AC transmission device of the present invention;

Fig. 8 is for carrying out the flow chart of the embodiment of consistency judgement in the control guard method according to flexible AC transmission device of the present invention;

Fig. 9 is for carrying out the flow chart of another embodiment of consistency judgement in the control guard method according to flexible AC transmission device of the present invention;

Figure 10 is for carrying out the flow chart of another embodiment of consistency judgement in the control guard method according to flexible AC transmission device of the present invention;

Figure 11 carries out the flow chart of the embodiment of signal selection for not meeting the consistency judgement in control guard method according to the present invention;

Figure 12 carries out the flow chart of another embodiment of signal selection for not meeting the consistency judgement in control guard method according to the present invention.

Embodiment

With reference to the accompanying drawings the present invention is described more fully, exemplary embodiment of the present invention wherein is described.Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not making under the creative work prerequisite the every other embodiment obtained, belong to the scope of protection of the invention.

Importance due to the MOV branch road; according to one embodiment of present invention; for crucial main equipment MOV installs two or more redundant measurement CT; the measuring-signal that two or more are measured to CT carries out the consistency judgement; if measuring-signal meets the consistency judgement; using measuring-signal as credible measuring-signal, for follow-up protection, control; if do not meet the consistency judgement; can also reject undesired signal by subsequent treatment; guarantee as far as possible the reliability of measuring-signal; prevent from controlling the protection system malfunction, improve the reliability of controlling protection system.

Below in conjunction with each figure and embodiment, technical scheme of the present invention is carried out to many-sided description.

Fig. 1 is the schematic diagram of the two CT of measurement of MOV branch road band in the fixed series compensation device according to an embodiment of the invention.As shown in Figure 1, whole power circuit system comprises bus 11, fixed series capacitors 12, MOVA 13 and spark gap 14.Wherein, two of MOV branch road installings, measure CT (two redundant measurement CT) CT21 and CT22, measure respectively the electric current of MOV branch road, the current value recorded is designated as respectively i _mOVA1and i _mOVA2.

The string that Fig. 2 is one embodiment of the invention is mended the schematic diagram of controlling protection system in device.String is mended configuration in device and is controlled protection system 22, also can control protection systems 23, two covers to protection system 22 redundant configuration and control the protection system independent operatings, is independently measured, data collection and control protects.Take system 22 as example, data acquisition unit 221 is measured the CT21 collection signal from each, collection is arranged on the measuring-signal of two or more measurements CT of metal oxide pressure-limiting device MOV branch road, and the described measuring-signal that two or more measure CT is sent to control protective unit 222; 222 pairs of described measuring-signals that two or more measure CT of control protective unit carry out the consistency judgement, if meet the consistency judgement carry out conservation treatment as credible measuring-signal.If, when judgement has fault, 222 pairs of circuit breakers of control protective unit/switch operation mechanism 24 sends relevant protection action command, as triggered GAP25, closing bypass breaker 26 etc.

Measurement CT to the MOV branch road has adopted Redundancy Design, and two or more current signals of measuring CT of same MOV branch road are carried out to the consistency judgement, then carry out corresponding primary equipment protection calculation, thus the generation of pre-anti-misoperation effectively.

Fig. 3 is the schematic diagram for the control protection system of one embodiment of the invention.Data acquisition unit 32 is collection signal from measure CT1,2; convert light signal to and send to control protective unit 33; 33 pairs of these digital signals of control protective unit are carried out true and false judgement; with judging the protection algorithm that carrys out the finishing device primary equipment for genuine signal; monitor relevant switching value information simultaneously; when the system failure or plant failure, provide relevant protection action command.

The installing of MOVA branch road is measured CT311, is measured CT312, measures the electric current of same MOV circuit.

According to one embodiment of present invention, data acquisition unit 32 comprises: EMI filter 321, and the transmission of measuring on the CT transmission line for filtering is disturbed; Signal condition unit 322, for current signal is adjusted, make its demand that meets A/D unit 323, also plays the effect that realizes again electrical isolation simultaneously; A/D unit 323, for receiving signal by analog signal and being converted to digital signal, import control protective unit 33 into by light path.

According to one embodiment of present invention, data summarization unit 331 receiving optical signals, change into the signal of telecommunication by it, and therefrom parse sampled data, and the measuring-signal that then by predetermined data format, will measure CT sends to consistency judging unit 332; The measuring-signal that two or more of 332 pairs of metal oxide pressure-limiting device MOV branch roads of consistency judging unit are measured CT carries out the consistency judgement, and the believable measuring-signal that meets the consistency judgement is sent to described protected location 333; Protected location 333 receives believable measuring-signal, carries out protection algorithm and control strategy, the output protection action command.

According to one embodiment of present invention, establish the electric current of measuring CT21, measurement CT22 measurement MOV branch road and be designated as respectively i _mOVA1and i _mOVA2the measuring-signal that 332 pairs of consistency judging units are measured CT311, measurement CT312 carries out the consistency judgement.

Same MOV tributary signal is carried out to the consistency judgement and adopts following principle:

Judgment mode 1:

|i _MOVA1-i _MOVA2|≤Δi (1)

Judgment mode 2:

$\frac{|i_{\mathrm{MOVA}2}-i_{\mathrm{MOVA}1}|}{\left|i_{\mathrm{MOVA}1}\right|+\left|i_{\mathrm{MOVA}2}\right|}\≤\mathrm{\δ}\%---\left(2\right)$

Judgment mode 3: if i _mOVA1and i _mOVA2be worth larger, employing formula (1) judgement;

If i _mOVA1and i _mOVA2be worth less, employing formula (2) judgement.

Wherein, i _mOVA1and i _mOVA2be respectively the measurement current value of two CT, the certainty of measurement of the measurement CT that Δ i and δ % value can adopt according to device is determined.

If i _mOVA1and i _mOVA2meet in above-mentioned three criterions any one, mean that MOVA branch road two is measured the CT measurement data consistent, by this, consistent data send to protected location 333 by the agreement of making an appointment after selecting one to arrange.

The schematic diagram of the control protective unit in the control protection system that Fig. 4 A is another embodiment of the present invention.In this embodiment, control protective unit 43 comprises data summarization unit 431, consistency judging unit 432, measuring-signal selected cell 433, protected location 436.

Data summarization unit 431 receiving optical signals, it is changed into to the signal of telecommunication, and therefrom parse sampled data, and the measuring-signal that then by predetermined data format, will measure CT passes to consistency judging unit 432, and consistency judging unit 432 obtains bypass breaker position signalling S _bCB; Control protective unit 43 comprises test signal selected cell 433, determine and do not meet consistency checking when consistency judging unit 432, measuring-signal selected cell 433, for test signal is selected, sends to described protected location 436 by the believable measuring-signal of selecting; Protected location 436 receives believable measuring-signal, carries out protection algorithm and control strategy, the output protection action command.

According to one embodiment of present invention, selectable, measuring-signal selected cell 433 can obtain bypass breaker position signalling S _bCB, and according to bypass breaker position signalling S _bCBthe measuring-signal of State selective measurements CT.

According to one embodiment of present invention, control protective unit 43 can also comprise wave record playback unit 434, in the situation that fault or manually boot records current demand signal amount and switching signal amount, and realizes the playback to historical recorded wave file or user-defined file; Communications management unit 435 completes information interaction, and with the information interaction of the device such as background monitoring and information remote transmitting interface, function while issuing guidance command, school.

The schematic diagram of the control protective unit in the control protection system that Fig. 4 B is another embodiment of the present invention.As shown in the figure, alternatively, consistency judging unit 432 and measuring-signal selected cell 433 can be deployed in data summarization unit 431, and data summarization unit 431 can be obtained bypass breaker position signalling S _bCB, measuring-signal and the S of the measurement CT that consistency judging unit 432 receives according to data summarization unit 431 _bCBcarry out the consistency judgement, when consistency judging unit 432, determine and do not meet consistency checking, measuring-signal selected cell 433 is for being selected test signal.

The schematic diagram of the control protective unit in the control protection system that Fig. 4 C is another embodiment of the present invention.As shown in the figure, alternatively, consistency judging unit 432 and measuring-signal selected cell 433 can be deployed in protected location 436, and protected location 436 can obtain bypass breaker position signalling S _bCB, consistency judging unit 432 receives from data summarization unit 431 according to the measuring-signal and the S that measure CT _bCBcarry out the consistency judgement, when consistency judging unit 432, determine and do not meet consistency checking, measuring-signal selected cell 433 is for being selected test signal.

The single-phase schematic diagram of fixed series compensation of band that Fig. 5 is one embodiment of the present of invention MOV branch road in parallel, below in conjunction with Fig. 5, to the detailed description of making comparisons of measuring-signal selected cell 433 judgement test signals.

As shown in Figure 5, flexible AC transmission device comprises bypass breaker 51, spark gap 52, the damping circuit 53, platform 54, capacitor 55, the bus 56 that are comprised of resistance R 531 and MOV532 and reactance, dispose to measure on the line CT1, CT21, CT22, CT31, CT32, CT3-CT7, be used for respectively the current value on distinct device in device.Wherein, the MOV branch road comprises MOVA and MOVB, wherein measures CT21, measures CT22 for measuring the electric current of MOVA, i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, measure CT31, measure CT32 for measuring the electric current of MOVB, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road.

If i _mOVA1and i _mOVA2do not meet above-mentioned consistency judgement, can use following judgement:

If branch road MOVA and MOVB are even configurations, work as i _mOVA1and i _mOVA2when inconsistent, by i _mOVA1and i _mOVA2respectively with the MOVB branch road in current i _mOVb1and i _mOVb2mean value compare, what difference was large is undesired signal; In like manner, work as i _mOVB1and i _mOVB2when inconsistent, by i _mOVB1and i _mOVB2respectively with the MOVA branch road in current i _mOVA1and i _mOVA2mean value compare, what difference was larger is undesired signal.

If branch road MOVA and MOVB, by certain proportional arrangement, record the mean value of electric current according to two measurement CT in the MOVB branch road, calculate the i of current value in the MOVA branch road by allocation ratio _{m flows into OVA0}; By i _mOVA1and i _mOVA2respectively with i _mOVA0compare, what difference was larger is undesired signal.

For example MOVA and MOVB are for configuring by 1: 3, and, when the electric current of MOVA branch road is 1, the electric current of MOVB is 3.For example, current value i in the MOVB branch road _mOVb1be 6, i _mOVb2be 6, in the MOVB branch road two measure CT record electric current mean value be 6, by 1: 3, calculate, the i of MOVA branch road _mOVA0current value is 2 in theory, by i _mOVA1and i _mOVA2with i _mOVA0theoretical value 2 compares, and what difference was larger is undesired signal.

If i _mOVA1and i _mOVA2do not meet the consistency judgement, can use another judgement yet:

According to Kirchhoff's current law (KCL), " in lumped-circuit, any moment, to arbitrary node, the algebraical sum identically vanishing of the branch current of all inflow nodes ".

Introduce bypass breaker mode bit S in criterion _bCB(S _bCB=0 means that bypass breaker is in open mode, S _bCB=1 means that bypass breaker is in closure state).

In Fig. 5, the electric current of MOVA branch road is i _mOV1, the electric current of MOVB branch road is i _mOV2, work as S _bCB, for node A, according to Kirchhoff's current law (KCL), the circuit current i is arranged at=0 o'clock _line, platform 54 current i _pf, capacitor 55 current i _c, the current i of MOVA branch road _mOV1, the MOVB branch road current i _mOV2, spark gap 52 current i _gAP, bypass breaker 51 current i _bCBsum is zero.

That is:

i _line+i _pf+i _c+i _MOV1+i _MOV2+i _GAP+i _BCB＝0 (3)

Because the measurement CT that is provided with redundancy on MOVA, MOVB branch road is measured current value, take the MOVA branch road as example, measure CT21, measure CT22 for measuring the electric current of MOVA, i _mOVA1and i _mOVA2being respectively in the MOVA branch road two measurement current values of measuring CT, is series system owing to measuring CT21, measurement CT22, so current i in theory _mOVA1and i _mOVA2current value equates, is the current i of MOVA branch road _mOV1, i.e. i _mOV1=i _mOVA1=i _mOVA2.Reason based on identical, current i in theory _mOVB1and i _mOVB2current value equates, is the current i of MOVB branch road _mOV1, i.e. i _mOV2=i _mOVB1=i _mOVB2.Constant (the i of current value that keeps the MOV2 branch road _mOV2for current i _mOVB1with i _mOVB2in a value), by i _mOVA1with i _mOVA2(3) formula of bringing into is respectively calculated, the absolute value of operation result closer to 0 value for more credible.In like manner, for the current value i of MOV2 branch road _mOVB1, i _mOVB2, the current value of maintenance MOV1 branch road is constant (is the current i of MOV1 branch road _mOVA1with i _mOVA2in a value), by i _mOVB1with i _mOVB2(3) formula of bringing into is respectively calculated, the absolute value of operation result closer to 0 value for more believable.

Same, if i _mOVB1and i _mOVB2do not meet the consistency judgement, can use above-mentioned judgement yet, judge relatively believable measured value.

The two CT schematic diagrams of measuring of the MOV branch road band of the fault current limiter that Fig. 6 is one embodiment of the invention, comprise the damping circuit that DG69, DR6A and DL68 form, switch 66, by-pass switch 61, resistance R 62, inductance L 63, bus 6B, wherein set up MOV tributary signal preprocessing function, at MOV branch road installing redundant measurement CT, measuring CT can be 2, also can be for more than 2, and the single CT that measures of still installing of other branch road.Under normal circumstances, reactor 67 in the series resonance state, does not affect the normal operation of system with capacitor 65, when system is short-circuited fault, with thyristor valve 64 fast conductings of Parallel-connected Capacitor, capacitor is by bypass fast, and reactor 67 seals in limiting short-circuit current in circuit.The installing of MOVA branch road is measured CT21, is measured CT22, for measuring the electric current of MOVA, is designated as respectively i _mOVA1and i _mOVA2.Signal to same MOV branch road carries out the consistency judgement, weeds out the data that difference is large, carries out the consistency judgment principle identical with the judgment principle in top described fixed series capacitors compensation arrangement.

Fig. 7 is the flow chart according to an embodiment of the control guard method of flexible AC transmission device of the present invention.As shown in Figure 7, step 702, collection is arranged on the measuring-signal of two or more measurements CT of metal oxide pressure-limiting device MOV branch road;

Step 704, the measuring-signal that two or more are measured to CT carries out the consistency judgement, if meet the consistency judgement processed as credible measuring-signal, for follow-up conservation treatment.

In above-described embodiment; measure by two or more signal measurement that CT carries out metal oxide pressure-limiting device MOV branch road; and measuring-signal is carried out to the consistency judgement; to the measuring-signal that meets consistency judgement as credible measuring-signal for follow-up conservation treatment; can reduce the possibility of MOV current protection and MOV unbalance protection generation malfunction, thereby improve the reliability that string is mended the control defencive function of device/fault current limiter device.

Fig. 8 is the flow chart according to an embodiment of the control guard method of flexible AC transmission device of the present invention.Be provided with two at metal oxide pressure-limiting device MOV branch road and measure CT; i _mOV1and i _mOV2be respectively two measurement current values of measuring CT that arrange at metal oxide pressure-limiting device MOV branch road.

Step 802, obtain i _mOVA1and i _mOVA2;

Step 803 judges whether to meet: | i _mOV1-i _mOV2|≤Δ i, wherein Δ i is judgment threshold;

Step 804, if meet, two measurement current values of measuring CT that the MOV branch road arranges are measured unanimously, meet the consistency judgement.

Fig. 9 is for carrying out the flow chart of another embodiment of consistency judgement in the control guard method according to flexible AC transmission device of the present invention.

Step 902, obtain i _mOVA1and i _mOVA2;

Step 903 judges whether to meet:

$\frac{|i_{\mathrm{MOV}2}-I_{\mathrm{MOV}1}|}{\left|i_{\mathrm{MOV}1}\right|+\left|i_{\mathrm{MOV}2}\right|}\≤\mathrm{\δ}\%;$ δ % is judgment threshold;

Step 904, if meet, two measurement current values of measuring CT that the MOV branch road arranges are measured unanimously, meet the consistency judgement.

Figure 10 is for carrying out the flow chart of another embodiment of consistency judgement in the control guard method according to flexible AC transmission device of the present invention.

Step 1002, obtain i _mOVA1and i _mOVA2; ;

Step 1003, judgement i _mOV1and i _mOV2the size of value:

If i _mOV1and i _mOV2be worth greatlyr, perform step 1004, judgement i _mOV1and i _mOV2whether meet: | i _mOV1-i _mOV2|≤Δ i;

Step 1005, if meet, two measurement current values of measuring CT that the MOV branch road arranges are measured unanimously, meet the consistency judgement;

If i _mOV1and i _mOV2be worth littlely, perform step 1006, judge whether to meet:

$\frac{|i_{\mathrm{MOV}2}-I_{\mathrm{MOV}1}|}{\left|i_{\mathrm{MOV}1}\right|+\left|i_{\mathrm{MOV}2}\right|}\≤\mathrm{\δ}\%,$ δ % is judgment threshold;

Step 1007, if meet, two measurement current values of measuring CT that the MOV branch road arranges are measured unanimously, meet the consistency judgement.

Figure 11 carries out the flow chart of the embodiment of signal selection for not meeting the consistency judgement in control guard method according to the present invention.Metal oxide pressure-limiting device MOV branch road comprises MOVA branch road in parallel and MOVB branch road, and MOVA branch road and MOVB branch road are respectively arranged with two and measure CT, wherein i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road;

Step 1102, the configuration distribution condition of judgement branch road MOVA and MOVB;

Evenly configuration, perform step 1103, by i if _mOVA1and i _mOVA2respectively with the i of MOVB branch road _mOVB1and i _mOVB2mean value compare;

Step 1104, in comparative result, what difference was larger is undesired signal;

If branch road MOVA and MOVB are by certain proportional arrangement, perform step 1105, according to i in the MOVB branch road _mOVB1and i _mOVB2mean value, calculate current value i in the MOVA branch road by allocation ratio _mOVA0;

Step 1106, by i _mOVA1and i _mOVA2respectively with i _mOVA0compare;

Step 1107, in comparative result, what difference was larger is undesired signal.

Figure 12 carries out the flow chart of another embodiment of signal selection for not meeting the consistency judgement in control guard method according to the present invention.Metal oxide pressure-limiting device MOV branch road is applied to string and mends in device or fault current limiter, string is mended in device or fault current limiter bypass breaker is set, metal oxide pressure-limiting device MOV branch road comprises MOVA branch road in parallel and MOVB branch road, and the MOVA branch road is provided with two and measures CT, wherein i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road;

Step 1202 selects electric current to converge node in the lumped-circuit that comprises described metal oxide pressure-limiting device MOV branch road, makes the electric current on described MOVA branch road and MOVB branch road can both flow into this node, for example, is the node A in Fig. 5;

Step 1203, when described bypass breaker, during in open mode, the algebraic value of all electric currents of convection current ingress A is carried out read group total;

Step 1204, be fixed as i by the current value of MOVB branch road _mOVB1or i _mOVB2, and the current value of establishing the MOVA branch road is respectively i _mOVA1and i _mOVA2;

Step 1205, at i _mOVA1and i _mOVA2in, the absolute value of selecting to make described read group total result is believable measuring-signal closer to 0 current value.

Embodiment from above can find out, embodiments of the invention have adopted Redundancy Design to the measurement CT of MOV branch road, and the two or more current signals of measuring CT to same MOV branch road are judged in controlling protection system, weed out rub-out signal, carry out again corresponding MOV protection calculation, guarantee that malfunction does not occur for MOV current protection and MOV unbalance protection, thereby improved the reliability that string is mended the control defencive function of device/fault current limiter device; Indirectly improve the environment tolerance of measuring system, guaranteed the stability of measuring system and the reliability of image data; And can prevent string to mend unnecessary out of service of device that the unit protection misoperation causes, thereby significantly improve availability factor and the utilance of package unit.

Description of the invention provides for example with for the purpose of describing, and is not exhaustively or limit the invention to disclosed form.Many modifications and variations are obvious for the ordinary skill in the art.Selecting and describing embodiment is for better explanation principle of the present invention and practical application, thereby and makes those of ordinary skill in the art can understand the various embodiment with various modifications that the present invention's design is suitable for special-purpose.

Claims (10)

1. the control protection system of a flexible AC transmission device, described control protection system comprises data acquisition unit, control protective unit, it is characterized in that:

Described data acquisition unit is collected two measuring-signals of measuring CT that are arranged on metal oxide pressure-limiting device MOV branch road, and described two measuring-signals of measuring CT are sent to described control protective unit;

Described control protective unit carries out the consistency judgement to described two measuring-signals of measuring CT, if meet the consistency judgement carry out conservation treatment as credible measuring-signal;

Described control protective unit comprises: the consistency judging unit; Described consistency judging unit carries out the consistency judgement to two measuring-signals of measuring CT of metal oxide pressure-limiting device MOV branch road;

Wherein, described two the measuring-signal i that measure CT of described consistency judgment unit judges _mOV1and i _mOV2whether meet:

|i _MOV1-i _MOV2|≤Δi;

Perhaps,

Described two the measuring-signal i that measure CT of described consistency judgment unit judges _mOV1and i _mOV2whether meet:

$\frac{|i_{\mathrm{MOV}2}-i_{\mathrm{MOV}1}|}{\left|i_{\mathrm{MOV}1}\right|+\left|i_{\mathrm{MOV}2}\right|}\≤\mathrm{\δ}\%;$

Perhaps,

If i _mOV1and i _mOV2be worth larger, described two the measuring-signal i that measure CT of described consistency judgment unit judges _mOV1and i _mOV2whether meet:

|i _MOV1-i _MOV2|≤Δi;

If i _mOV1and i _mOV2be worth less, described two the measuring-signal i that measure CT of described consistency judgment unit judges _mOV1and i _mOV2whether meet:

$\frac{|i_{\mathrm{MOV}2}-i_{\mathrm{MOV}1}|}{\left|i_{\mathrm{MOV}1}\right|+\left|i_{\mathrm{MOV}2}\right|}\≤\mathrm{\δ}\%;$

I wherein _mOV1and i _mOV2be respectively two measurement current values of measuring CT that arrange at metal oxide pressure-limiting device MOV branch road, △ i and δ % are judgment threshold,

If meet, meet the consistency judgement.

2. the system as claimed in claim 1 is characterized in that:

Described control protective unit also comprises: data summarization unit and protected location;

Wherein, described data summarization unit receives described two measuring-signals of measuring CT, and described two measuring-signals of measuring CT are sent to described consistency judging unit;

The believable measuring-signal that described consistency judging unit will meet the consistency judgement sends to described protected location;

Described protected location receives described believable measuring-signal, carries out protection algorithm and control strategy, the output protection action command.

3. system as claimed in claim 2 is characterized in that:

Described metal oxide pressure-limiting device MOV branch road comprises MOVA branch road in parallel and MOVB branch road, and MOVA branch road and MOVB branch road are respectively arranged with two and measure CT, wherein i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road;

Described control protective unit also comprises the measuring-signal selected cell;

If determine and do not meet consistency checking when the consistency judging unit, described measuring-signal selected cell is used for:

If branch road MOVA and MOVB are even configurations, by i _mOVA1and i _mOVA2respectively with the i of MOVB branch road _mOVB1and i _mOVB2mean value compare, judge i _mOVA1and i _mOVA2what difference was larger is undesired signal;

Perhaps,

If branch road MOVA and MOVB are by certain proportional arrangement, according to i in the MOVB branch road _mOVB1and i _mOVB2mean value, calculate current value i in the MOVA branch road by allocation ratio _mOVA0; By i _mOVA1and i _mOVA2respectively with i _mOVA0compare, judge i _mOVA1and i _mOVA2what difference was larger is undesired signal.

4. system as claimed in claim 2 is characterized in that:

Described metal oxide pressure-limiting device MOV branch road is applied to string and mends in device or fault current limiter, described string is mended in device or fault current limiter bypass breaker is set, described metal oxide pressure-limiting device MOV branch road comprises MOVA branch road in parallel and MOVB branch road, the MOVA branch road is provided with two and measures CT, wherein i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road;

Described control protective unit also comprises the measuring-signal selected cell;

If do not meet consistency checking, described measuring-signal selected cell is used for:

During in open mode, the current value of MOVB branch road is fixed as to i when described bypass breaker _mOVB1or i _mOVB2, inflow current is converged to the algebraic value of all electric currents of node (A) and carry out read group total, and the current value of establishing the MOVA branch road is respectively i _mOVA1and i _mOVA2, select i _mOVA1and i _mOVA2in make described read group total result absolute value closer to 0 current value, be believable measuring-signal;

Wherein, described electric current converges node (A) and is arranged in the lumped-circuit that comprises described metal oxide pressure-limiting device MOV branch road, and makes electric current on described MOVA branch road and MOVB branch road can both flow into described electric current to converge node (A).

5. as claim 3 or the described system of 4 claims; it is characterized in that: described measuring-signal selected cell and consistency judging unit are deployed in described data summarization unit, or described measuring-signal selected cell and consistency judging unit are deployed in described protected location.

6. as the described system of any one claim in claim 1 to 4, described system is mended device or fault current limiter for going here and there; Described string is mended device and fault current limiter comprises: fixed series capacitors compensation arrangement, thyristor controlled series capacitor compensation arrangement, series resonant-type fault current limiter device.

7. the control guard method of a flexible AC transmission device is characterized in that:

Collection is arranged on two measuring-signals of measuring CT of metal oxide pressure-limiting device MOV branch road;

Described two measuring-signals of measuring CT are carried out to the consistency judgement, if meet the consistency judgement processed as credible measuring-signal;

Wherein, described two measuring-signals of measuring CT being carried out to the consistency judgement is specially:

Judge whether to meet:

|i _MOV1-i _MOV2|≤Δi;

Perhaps,

Judge whether to meet:

$\frac{|i_{\mathrm{MOV}2}-i_{\mathrm{MOV}1}|}{\left|i_{\mathrm{MOV}1}\right|+\left|i_{\mathrm{MOV}2}\right|}\≤\mathrm{\δ}\%;$

Perhaps,

If i _mOV1and i _mOV2be worth larger, the judgement i _mOV1and i _mOV2whether meet:

|i _MOV1-i _MOV2|≤Δi;

If i _mOV1and i _mOV2be worth less, the judgement i _mOVA1and i _mOVA2whether meet:

$\frac{|i_{\mathrm{MOV}2}-i_{\mathrm{MOV}1}|}{\left|i_{\mathrm{MOV}1}\right|+\left|i_{\mathrm{MOV}2}\right|}\≤\mathrm{\δ}\%;$

If meet, meet the consistency judgement, wherein i _mOV1and i _mOV2be respectively two measurement current values of measuring CT that arrange at metal oxide pressure-limiting device MOV branch road, △ i and δ % are judgment threshold.

8. method as claimed in claim 7 is characterized in that:

Described metal oxide pressure-limiting device MOV branch road comprises MOVA branch road in parallel and MOVB branch road, and MOVA branch road and MOVB branch road are respectively arranged with two and measure CT, wherein i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road;

If do not meet consistency checking, judged:

If branch road MOVA and MOVB are even configurations, by i _mOVA1and i _mOVA2respectively with the i of MOVB branch road _mOVB1and i _mOVB2mean value compare, what difference was larger is undesired signal;

Perhaps,

If branch road MOVA and MOVB are by certain proportional arrangement, according to i in the MOVB branch road _mOVB1and i _mOVB2mean value, calculate current value i in the MOVA branch road by allocation ratio _mOVA0; By i _mOVA1and i _mOVA2respectively with i _mOVA0compare, what difference was larger is undesired signal.

9. method as claimed in claim 7 is characterized in that:

Described metal oxide pressure-limiting device MOV branch road is applied to string and mends in device or fault current limiter, described string is mended in device or fault current limiter bypass breaker is set, described metal oxide pressure-limiting device MOV branch road comprises MOVA branch road in parallel and MOVB branch road, the MOVA branch road is provided with two and measures CT, wherein i _mOVA1and i _mOVA2be respectively two measurement current values of measuring CT in the MOVA branch road, i _mOVB1and i _mOVB2be respectively two measurement current values of measuring CT in the MOVB branch road; If do not meet consistency checking, judged:

In the lumped-circuit that comprises described metal oxide pressure-limiting device MOV branch road, select electric current to converge node (A), make electric current on described MOVA branch road and MOVB branch road can both flow into described electric current and converge node (A);

, converge the algebraic value of all electric currents of node (A) to flowing into described electric current and carry out read group total during in open mode when described bypass breaker; Wherein the current value of MOVB branch road is fixed as to i _mOVB1or i _mOVB2, and the current value of establishing the MOVA branch road is respectively i _mOVA1and i _mOVA2; At i _mOVA1and i _mOVA2in, the absolute value of selecting to make described read group total result is believable measuring-signal closer to 0 current value;

Perhaps

The current value of MOVA branch road is fixed as to i _mOVA1or i _mOVA2, and the current value of establishing the MOVB branch road is respectively i _mOVB1and i _mOVB2; At i _mOVB1and i _mOVB2in, the absolute value of selecting to make described read group total result is believable measuring-signal closer to 0 current value.

10. as the described method of any one claim in claim 7 to 9, described method is mended device or fault current limiter for going here and there; Described string is mended device and fault current limiter comprises: fixed series capacitors compensation arrangement, thyristor controlled series capacitor compensation arrangement, series resonant-type fault current limiter device.

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