CN104578094A

CN104578094A - Capacitance switching method and device

Info

Publication number: CN104578094A
Application number: CN201410805809.1A
Authority: CN
Inventors: 黎柬; 冼成瑜; 郑吉祥
Original assignee: SHENZHEN CITY SHENGHONG ELECTRIC CO Ltd
Current assignee: SHENZHEN CITY SHENGHONG ELECTRIC CO Ltd
Priority date: 2014-12-22
Filing date: 2014-12-22
Publication date: 2015-04-29
Anticipated expiration: 2034-12-22
Also published as: CN104578094B

Abstract

The invention discloses a capacitance switching method and device, and relates to the reactive compensation technique of a power network so as to solve the problem that the capacitance cannot be switched timely in the prior art. The method comprises the following steps: detecting the undercompensation capacity of a current power network and the capacity of capacitance input in a capacitance cabinet; summing the undercompensation capacity and the input capacity so as to obtain total capacity; calculating input capacitance combinations which can provide the total capacity from the multiple-path capacitance of the capacitance cabinet; selecting the optimal input capacitance combination from the input capacitance combinations according to a first preset strategy; switching the corresponding capacitance in the capacitance cabinet according to the optimal input capacitance combination. The optimal capacitance switching combination can be calculated according to the undercompensation capacity or the over compensation capacity of the current power network, switching operation is performed on the corresponding capacitance of the capacitance cabinet according to the optimal capacitance switching combination, the capacitance can be switched timely according to the actual conditions of the power network, and the vibration of the power network caused by the switching can be reduced.

Description

A kind of capacitor switching method and device

Technical field

The present invention relates to electric network reactive compensation technology, more particularly, relate to a kind of capacitor switching method and device.

Background technology

Along with the high speed development of national economy and the raising of living standards of the people, the demand of people to electric power is growing, has higher requirement to the reliability of powering and power supply quality simultaneously.Due to the continuous increase of load, and the significantly increase of power supply, not only change the network configuration of electric power system, have also been changed the power distribution of system, cause the reactive power distribution of system unreasonable, even may cause the idle wretched insufficiency in some areas, situation that voltage levvl is generally lower.Along with system configuration is increasingly sophisticated, when system is subject to larger interference, just may cause voltage collapse in voltage stabilization weak link.

The rational selection of reactive power compensation point and the determination of compensation capacity, can maintain the voltage levvl of system effectively, improves the voltage stability of system, avoid long-distance transmissions idle in a large number, thus reduce active power loss, reduces generating expense.Usually, by throw-cut device for capacitor, switching control is carried out to the multichannel electric capacity in capacitor box, for electrical network provides suitable compensation capacity, thus electric network reactive-load is compensated.And traditional capacitor switching technology exists such as due at every turn can only switching electric capacity and the switching defect etc. not in time that causes, effect and the consistency in electric capacity life-span of reactive power compensation are had a strong impact on.

Summary of the invention

The present invention is just to the switching defect not in time that the capacitor switching technology of prior art exists, a kind of capacitor switching method and device are provided, can combine according to the capacitor switching of the undercompensation capacity of current electric grid or overcompensation calculation of capacity the best, and according to the capacitor switching combination of the best, switching operation is carried out to the corresponding capacitance of capacitor box, switching is timely, and compensation effect is good.

The technical scheme that the present invention solves the employing of its technical problem is: provide a kind of capacitor switching method, comprise the following steps:

The capacity of the electric capacity dropped in S11, detection current electric grid undercompensation capacity and capacitor box;

S12, by undercompensation capacity and dropped into capacity summation to obtain total capacity;

S13, the dropped into capacitor combination calculating and described total capacity can be provided of falling into a trap from the multichannel electric capacity of capacitor box;

S14, according to the first preset strategy from described drop into capacitor combination to select best drop into capacitor combination;

S15, according to described the best drop into capacitor combination switching is carried out to the corresponding capacitance in described capacitor box.

Preferably, described capacitor box comprises multichannel electric capacity, and every road electric capacity is encoded according to its compensation capacity, and from first electric capacity with maximum compensation capacity, the compensation capacity of each road electric capacity is maximum compensation capacity afterwards.

Preferably, the described first default plan comprises one or more substrategy following:

With the minimum substrategy for foundation of electrical network concussion;

With the minimum substrategy for foundation of the electric capacity quantity participating in work after switching;

With electric capacity by substrategy that the least number of times of switching is foundation;

For the electric capacity of identical capacity with the operating time the shortest substrategy for foundation;

With response speed the soonest for the substrategy of foundation.

A kind of capacitor switching method is provided, comprises the following steps:

The capacity of the electric capacity excised in S21, detection current electric grid overcompensation capacity and capacitor box;

S22, by overcompensation capacity and excised capacity summation to obtain total capacity;

S23, the excised capacitor combination calculating and described total capacity can be provided of falling into a trap from the multichannel electric capacity of capacitor box;

S24, select best excision capacitor combination according to the second preset strategy from described excision capacitor combination;

S25, according to described the best excision capacitor combination switching is carried out to the corresponding capacitance in described capacitor box.

Preferably, described second preset strategy comprises one or more substrategy following:

With the minimum substrategy for foundation of electrical network concussion;

For the electric capacity of identical capacity with the operating time the longest substrategy for foundation;

With response speed the soonest for the substrategy of foundation.

S300, judge that the state of current electric grid is undercompensation state or overcompensation state, if undercompensation state then performs step S301-S305, if overcompensation state then performs step S306-S310;

The capacity of the electric capacity dropped in S301, detection current electric grid undercompensation capacity and capacitor box;

S302, by undercompensation capacity and dropped into capacity summation to obtain total capacity;

S303, the dropped into capacitor combination calculating and described total capacity can be provided of falling into a trap from the multichannel electric capacity of capacitor box;

S304, according to the first preset strategy from described drop into capacitor combination to select best drop into capacitor combination;

S305, according to described the best drop into capacitor combination switching is carried out to the corresponding capacitance in described capacitor box;

The capacity of the electric capacity excised in S306, detection current electric grid overcompensation capacity and capacitor box;

S307, by overcompensation capacity and excised capacity summation to obtain total capacity;

S308, the excised capacitor combination calculating and described total capacity can be provided of falling into a trap from the multichannel electric capacity of capacitor box;

S309, select best excision capacitor combination according to the second preset strategy from described excision capacitor combination;

S310, according to described the best excision capacitor combination switching is carried out to the corresponding capacitance in described capacitor box.

A kind of capacitor switching device is provided, comprises:

First detecting unit, for detecting the capacity of the electric capacity dropped in current electric grid undercompensation capacity and capacitor box;

First sum unit, for by undercompensation capacity and dropped into capacity summation to obtain total capacity;

Capacitor combination computing unit can be dropped into, for the dropped into capacitor combination calculating and can provide described total capacity of falling into a trap from the multichannel electric capacity of capacitor box;

Best input capacitor combination selected cell, for selecting best input capacitor combination according to the first preset strategy from described input capacitor combination;

First control unit, carries out switching for dropping into capacitor combination according to described the best to the corresponding capacitance in described capacitor box.

A kind of capacitor switching device is provided, comprises:

Second detecting unit, for detecting the capacity of the electric capacity excised in current electric grid overcompensation capacity and capacitor box;

Second sum unit, for by overcompensation capacity and excised capacity summation to obtain total capacity;

Capacitor combination computing unit can be excised, for the excised capacitor combination calculating and can provide described total capacity of falling into a trap from the multichannel electric capacity of capacitor box;

Best excision capacitor combination selected cell, for selecting best excision capacitor combination according to the second preset strategy from described excision capacitor combination;

Second control unit, for carrying out switching according to described the best excision capacitor combination to the corresponding capacitance in described capacitor box.

A kind of capacitor switching device is provided, comprises:

Judging unit, for judging that the state of current electric grid is undercompensation state or overcompensation state;

First detecting unit, for when current electric grid is undercompensation state, detects the capacity of the electric capacity dropped in current electric grid undercompensation capacity and capacitor box;

First control unit, carries out switching for dropping into capacitor combination according to described the best to the corresponding capacitance in described capacitor box;

Second detecting unit, for when current electric grid state is overcompensation state, detects the capacity of the electric capacity excised in current electric grid overcompensation capacity and capacitor box;

Capacitor switching method of the present invention and device have following beneficial effect: can combine according to the capacitor switching of the undercompensation capacity of current electric grid or overcompensation calculation of capacity the best, and according to the capacitor switching combination of the best, switching operation is carried out to the corresponding capacitance of capacitor box, can according to the timely switching capacitance of the actual conditions of electrical network, and the electrical network concussion that switching brings can be reduced.

Accompanying drawing explanation

Fig. 1 is the flow chart of capacitor switching method first embodiment of the present invention;

Fig. 2 is the flow chart of capacitor switching method second embodiment of the present invention;

Fig. 3 is the flow chart of capacitor switching method of the present invention 3rd embodiment;

Fig. 4 is the logic diagram of capacitor switching device first embodiment of the present invention;

Fig. 5 is the logic diagram of capacitor switching device second embodiment of the present invention;

Fig. 6 is the logic diagram of capacitor switching device the 3rd embodiment of the present invention.

Embodiment

The embodiment of the present invention provides a kind of capacitor switching method and device, solve in existing capacitor switching technology due at every turn can only switching electric capacity and the switching defect not in time caused, by combining according to the undercompensation capacity of current electric grid or the capacitor switching of overcompensation calculation of capacity the best, and according to the capacitor switching combination of the best, switching operation is carried out to the corresponding capacitance of capacitor box, thus make capacitor switching in time and reactive power compensation effect good.

Below in conjunction with drawings and Examples the present invention will be further explained explanation.

Fig. 1 is the flow chart of capacitor switching method first embodiment of the present invention, and as shown in Figure 1, in the present embodiment, capacitor switching method comprises the following steps:

Capacitor switching method of the present invention can be applied to static var compensator (SVGC), SVGC based on electrical network actual needs compensate idle, switching operation is carried out to the electric capacity in capacitor box, thus provides corresponding compensation capacity for electrical network.

Concrete, in step s 11, static var compensator detects the under-compensated capacity of current electric grid (namely also needing the compensation capacity for electrical network provides), and the capacity of the electric capacity dropped in capacitance present cabinet (capacity namely compensated).In the present embodiment, capacitor box comprises multichannel electric capacity, and every road electric capacity is encoded according to its compensation capacity, and from first electric capacity with maximum compensation capacity, the compensation capacity of each road electric capacity is maximum compensation capacity afterwards.That is, the corresponding a kind of coding of capacitor box, in capacitor box, the way of way and the coding of electric capacity can together also can be different.Such as, the capacitor box being encoded to 1:2:3:6 only has three road electric capacity to different situations, and namely compensation capacity is the first via electric capacity of 1Kvar, and compensation capacity is the second road electric capacity of 2Kvar, and compensation capacity is the 3rd road electric capacity of 3Kvar, and the 4th road electric capacity can not be used.Identical situation such as, the capacitor box being encoded to 1:2:3:6 has four road electric capacity, namely compensation capacity is the first via electric capacity of 1Kvar, and compensation capacity is the second road electric capacity of 2Kvar, the 4th road electric capacity of compensation capacity to be the 3rd road electric capacity of 3Kvar and building-out capacitor be 6Kvar.In addition, suppose that capacitor box uses N road coding (N belongs to natural number), first there is maximum be encoded to X road (X is less than or equal to N), then X road is maximum to the coding on N road.Adjustment electric capacity is called to the electric capacity of the coding correspondence on X-1 road by the 1st, X road is called maximum capacitor to the electric capacity of the coding correspondence on N road, the order of adjustment electric capacity can be random, but must be corresponding with coding, the coding of such as 1.3.2.6, the compensation capacity of the capacity on first to fourth road is 1Kvar, 3Kvar, 2Kvar and 6Kvar successively.

Due to from first, there is maximum compensation capacity electric capacity, the compensation capacity of each road electric capacity is maximum compensation capacity afterwards, capacitive encoder is as 1:1:1:1,1:2:4:4:, 1:1:2:4,1:2:3:6 and 1:2:3:6:6, such capacitive encoder has a feature, when the way of electric capacity in capacitor box is greater than or equal to the way of adjustment electric capacity, any compensation capacity within maximum compensation capacity can be realized by the combination of electric capacity.When the way of electric capacity is less than the way of adjustment electric capacity, any compensation capacity within maximum compensation capacity is by the incompatible realization of capacitance group closest to this compensation capacity in capacitor combination.Now for the way of electric capacity be greater than adjustment electric capacity way and equal encode way, the coding of such as 1:2:3:6, the capacity of its first via electric capacity is 1Kvar, the capacity of the second road electric capacity is 2Kvar, the capacity of the 3rd road electric capacity is the capacity of 3Kvar and the 4th road electric capacity is 6Kvar, heap(ed) capacity is that the arbitrary integer capacity in 6Kvar, 1-6Kvar can both be realized by the combination of 1,2,3 and 6.

In step s 12, the capacity of under-compensated for current electric grid capacity with the electric capacity dropped into is sued for peace by static var compensator, obtains total capacity.For 1:2:3:6, the under-compensated capacity of current electric grid is 4Kvar, and the second road electric capacity in four road electric capacity comes into operation, and the total capacity (namely not dropping into total undercompensation capacity during electric capacity) that both summations draw is 4+2=6Kvar.

In step s 13, static var compensator, according to the total capacity calculated in the capacitive encoder of capacitor box and step S12, calculates the combination that can provide the electric capacity of total capacity in the multichannel electric capacity of capacitor box, can drop into capacitor combination.As precedent, the total capacity calculated in step S12 is 6Kvar, and the capacitive encoder of capacitor box is 1:2:3:6, therefore, it is possible to provide the capacitor combination of 6Kvar to be 1:2:3 and 6 these two kinds, namely simultaneously drop into the first via to the 3rd tunnel or only drop into the 6th tunnel.Way for electric capacity is less than the situation of the way of adjustment electric capacity, selects the capacitor combination of the closest total capacity calculated of compensation capacity that can provide.

Static var compensator stores the first preset strategy, will select best input capacitor combination in step S14 according to the first preset strategy from the dropped into capacitor combination that step S13 calculates.First preset strategy comprises one or more substrategy following: the substrategy being foundation with electrical network concussion minimum (namely the capacitance of synchronization switching is minimum), with the minimum substrategy for foundation of the electric capacity quantity participating in work after switching, with electric capacity by substrategy that the least number of times of switching is foundation, for the electric capacity of identical capacity with the operating time the shortest substrategy for foundation and take response speed the fastest (capacitor switching action in capacitor combination can be dropped into namely minimum) as the substrategy of foundation.User can according to the actual needs, select arbitrary substrategy to combine.

When using substrategy for foundation minimum with the capacitance of synchronization switching, electrical network can be made to shake and to minimize.As precedent, the dropped into capacitor combination selected in step s 13 is 1:2:3 and 6, and the second road electric capacity drops into.If select 1:2:3 combination, then need successively to drop into the first via and the 3rd road electric capacity, electrical network synchronization needs to bear the concussion that 3 unit capacitys cause.If select 6 combinations, then need excision second road electric capacity, drop into the 4th road electric capacity, electrical network synchronization need bear the concussion that 6 specific capacitances cause.Therefore, according to the minimum substrategy for foundation of the capacitance of synchronization switching, selection 1:2:3 is combined as best input capacitor combination.

When use to participate in the minimum substrategy for foundation of the electric capacity quantity of work after with switching time, the multiplex circuit in capacitor box can be protected well.As precedent, the dropped into capacitor combination selected in step s 13 is 1:2:3 and 6, and the second road electric capacity drops into.If select 1:2:3 combination, then need 3 electric capacity work, mean the first to the 3rd tunnel totally 3 electric capacity subject loss.If select 6 combinations, then need excision second road electric capacity, drop into the 4th road electric capacity, only have the 4th road electric capacity in loss.Therefore, according to the minimum substrategy for foundation of the electric capacity quantity participating in work after switching, selection 6 is combined as best input capacitor combination.

Switching frequency due to electric capacity is limited, therefore uses with electric capacity by the substrategy that the least number of times of switching is foundation, can protect the multiplex circuit in capacitor box well.Its ventilative number of times once, will increase once by the every switching of each electric capacity in static var compensator.As precedent, the dropped into capacitor combination selected in step s 13 is 1:2:3 and 6, and the second road electric capacity drops into.First via capacitor switching 1 time, the 3rd road capacitor switching 4 times, the 4th road capacitor switching 2 times.Therefore, according to electric capacity by the substrategy that the least number of times of switching is foundation, selection 6 is combined as and best drops into capacitor combination.Again such as, capacitance group be encoded to 1:2:3:4:4:4, now need the capacity compensating 4Kvar again, 4th road capacitor switching 5 times, the 5th road capacitor switching 4 times, the 6th road capacitor switching 3 times, their capacity is 4, is criterion according to switching frequency, then select input the 6th tunnel.

When using the substrategy for foundation the shortest in operating time of the electric capacity for identical capacity, will preferentially excise the electric capacity of longevity of service, the electric capacity that the time of preferentially devoting oneself to work is short, electric capacity can be protected well.Capacitance group be encoded to 1:2:3:4:4:4, now need the capacity compensating 4Kvar again, the time that the 4th, the 5th and the 6th road electric capacity has worked is respectively 10,20 and 30 hours, as the capacity of 4 units need be dropped into, so preferentially drop into the 4th road electric capacity.

After each switching, all need through switching time delay, therefore when using so that the minimum substrategy for foundation of capacitor switching action in capacitor combination can be dropped into, can the fastest response speed be obtained, reach target the soonest.Such as 1:2:3:6 coding, each road electric capacity does not all drop into, and now needs the capacity of input 6 units, if select 1:2:3 combination, needs action 3 times, selects 6 combinations only to need action once.Therefore, select 6 combinations, namely the 4th road electric capacity is best input capacitor combination.

Sometimes, use single substrategy, it is not unique that the best selected drops into capacitor combination.Such as, the capacitance group of 1:2:3:6:6:6 coding, have 6 road electric capacity, need the capacity of input 6 units, the dropped into capacitor combination selected in step S13 is 6 combinations, and 6 combinations comprise the 4th road electric capacity, the 5th road electric capacity and the 6th road electric capacity.In step S14, if uniquely use can drop into the minimum substrategy for foundation of capacitor switching action in capacitor combination, and input the 4th, the 5th or the 6th road electric capacity all only needs action once, causes and then one cannot select best input capacitor combination.Now, can select to select arbitrarily a road and drop into capacitor combination from multiple meeting the combination of substrategy as the best.Also the combination of multiple substrategy can be used.Now, the multiple substrategys for using are needed to distribute priority, the high substrategy of priority is first used to select the best capacitor combination that drops into obtain the first result from dropping into capacitor combination, if combine not unique in the first result, then use priority time high substrategy from the first result, select best input capacitor combination ... by that analogy, until select unique the best to drop into capacitor combination.Such as, for so that the minimum substrategy assigned highest priority for foundation of capacitor switching action in capacitor combination can be dropped into, for the substrategy being foundation by the least number of times of switching with electric capacity distributes secondary high priority, for the electric capacity for identical capacity distributes minimum priority with the operating time the shortest substrategy for foundation, according to priority order from high to low, above-mentioned three kinds of substrategys are used to screen capacitor combination can be dropped into, draw unique result when using certain substrategy, then screen end.In this embodiment, because the electric capacity that employs identical capacity is with the operating time the shortest substrategy for foundation, and the switching time of electric capacity can not be equal, and the said All Policies that there will not be all has screened the also not unique situation of result.But time when combination for other substrategys, after may occurring having screened all word strategies, the situation that result is not unique, now acquiescence chooses one as and bestly drops into capacitor combination.

Last in step S15, static var compensator drops into capacitor combination according to the best selected in step S14 and carries out switching to the corresponding capacitance in capacitor box.

In the first embodiment of capacitor switching method of the present invention; from first electric capacity with maximum compensation capacity; the compensation capacity of each road electric capacity is maximum compensation capacity afterwards; the idle of arbitrary target value between from one to maximum compensation capacity can realize seamless compensation; also efficiently avoid simultaneously and mend or owe to mend the switching concussion caused, protected electric capacity well.Moreover; use the first preset strategy from all capacitor combinations dropped into, filter out best input capacitor combination; by the configuration of the first preset strategy, the concussion of electrical network can be reduced further and/or protect electric capacity better and/or obtain response speed faster.

Fig. 2 is the flow chart of capacitor switching method second embodiment of the present invention, and as shown in Figure 2, in the present embodiment, capacitor switching method comprises the following steps:

S25, according to the best excision capacitor combination switching is carried out to the corresponding capacitance in described capacitor box.

Different from capacitor switching method first embodiment of the present invention, in the present embodiment, main what pay close attention to is the situation of electrical network overcompensation.

In the step s 21, static var compensator detects the capacity (the unnecessary electric capacity namely dropped into) of current electric grid overcompensation, and the capacity of the electric capacity excised in capacitance present cabinet (being namely in the capacity of the electric capacity of excision state).In the present embodiment, capacitor box comprises multichannel electric capacity, and every road electric capacity is encoded according to its compensation capacity, and from first electric capacity with maximum compensation capacity, the compensation capacity of each road electric capacity is maximum compensation capacity afterwards.That is, the corresponding a kind of coding of capacitor box, the way of electric capacity and the way of coding can together also can not be identical.Capacitive encoder is as 1:1:1:1,1:2:4:4:, 1:1:2:4,1:2:3:6 and 1:2:3:6:6.Such capacitive encoder has a feature, and any compensation capacity within maximum compensation capacity can be realized by the combination of electric capacity.The way of encoding is equaled with the way of electric capacity, 1:2:3:6 is encoded to example, the capacity of its first via electric capacity is 1Kvar, the capacity of the second road electric capacity is 2Kvar, the capacity of the 3rd road electric capacity is the capacity of 3Kvar and the 4th road electric capacity is 6Kvar, heap(ed) capacity is that the arbitrary integer capacity in 6Kvar, 1-6Kvar can both be realized by the combination of 1,2,3 and 6.

In step S22, the capacity of the capacity of current electric grid overcompensation with the electric capacity excised is sued for peace by static var compensator, obtains total capacity.For 1:2:3:6, the capacity of current electric grid overcompensation is 4Kvar, and the second road electric capacity in four road electric capacity is cut (being namely in excision state), and the total capacity that both summations draw is 4+2=6Kvar.

In step S23, static var compensator, according to the total capacity calculated in the capacitive encoder of capacitor box and step S22, calculates the combination that can provide the electric capacity of total capacity in the multichannel electric capacity of capacitor box, can excise capacitor combination.As precedent, the total capacity calculated in step S22 is 6Kvar, the capacitive encoder of capacitor box is 1:2:3:6, therefore, the capacitor combination of 6Kvar can be provided to be 1:2:3 and 6 these two kinds (can capacitor combination be excised), namely to make the first via all be in excision state as the 3rd tunnel or only make the 6th tunnel be in excision state simultaneously.

Static var compensator stores the second preset strategy, will select best excision capacitor combination in step s 24 which according to the second preset strategy from the excised capacitor combination that step S23 calculates.Second presets plan comprises one or more substrategy following: the substrategy being foundation with electrical network concussion minimum (namely the capacitance of synchronization switching is minimum), with the minimum substrategy for foundation of the electric capacity quantity participating in work after switching, with electric capacity by substrategy that the least number of times of switching is foundation, for the electric capacity of identical capacity with the operating time the longest substrategy for foundation and the substrategy that is foundation with response speed the fastest (capacitor switching action in capacitor combination can be excised minimum).User can according to the actual needs, select arbitrary substrategy to combine.

When using substrategy for foundation minimum with the capacitance of synchronization switching, electrical network can be made to shake and to minimize.As precedent, the dropped into capacitor combination selected in step S23 is 1:2:3 and 6, and the second road electric capacity has been in excision state.If select 1:2:3 combination, then need successively the excision first via and the 3rd road electric capacity, electrical network synchronization needs to bear the concussion that 3 unit capacitys cause.If select 6 combinations, then need input second road electric capacity, then excise the 4th road electric capacity, electrical network synchronization need bear the concussion that 6 specific capacitances cause.Therefore, according to the minimum substrategy for foundation of the capacitance of synchronization switching, selection 1:2:3 is combined as best excision capacitor combination.

When use to participate in the minimum substrategy for foundation of the electric capacity quantity of work after with switching time, the multiplex circuit in capacitor box can be protected well.As precedent, the excised capacitor combination selected in step S23 is 1:2:3 and 6, and the second road electric capacity has been in excision state.If select 1:2:3 combination, then need the 4th road electric capacity work, namely only have 1 electric capacity subject loss.If select 6 combinations, then need input second road electric capacity, excision the 4th road electric capacity, the first via, the second tunnel and the 3rd road electric capacity are all in work, bear loss.Therefore, according to the minimum substrategy for foundation of the electric capacity quantity participating in work after switching, selection 1:2:3 is combined as best excision capacitor combination.

Switching frequency due to electric capacity is limited, therefore uses with electric capacity by the substrategy that the least number of times of switching is foundation, can protect the multiplex circuit in capacitor box well.Its ventilative number of times once, will increase once by the every switching of each electric capacity in static var compensator.As precedent, the excised capacitor combination selected in step S23 is 1:2:3 and 6, and the second road electric capacity excises.First via capacitor switching 1 time, the second road capacitor switching 1 time, the 3rd road capacitor switching 4 times, the 4th road capacitor switching 2 times.Therefore, according to electric capacity by the substrategy that the least number of times of switching is foundation, selection 6 is combined as and best drops into capacitor combination.Again such as, capacitance group be encoded to 1:2:3:4:4:4, the capacity of existing overcompensation 4Kvar, 4th road capacitor switching 5 times, the 5th road capacitor switching 4 times, the 6th road capacitor switching 3 times, their capacity is 4, is criterion according to switching frequency, then select input the 6th road electric capacity.

When using the substrategy for foundation the longest with the operating time of the electric capacity for identical capacity, will preferentially excise the electric capacity of longevity of service, the electric capacity that the time of preferentially devoting oneself to work is short, electric capacity can be protected well.Capacitance group be encoded to 1:2:3:4:4:4, the capacity of existing overcompensation 4Kvar, the time that the 4th, the 5th and the 6th road electric capacity has worked is respectively 10,20 and 30 hours, as excised the capacity of 4 units, so preferentially excises the 6th road electric capacity.

After each switching, all need through switching time delay, therefore when using so that the minimum substrategy for foundation of capacitor switching action in capacitor combination can be excised, can the fastest response speed be obtained, reach target the soonest.Such as 1:2:3:6 coding, each road electric capacity drops into all, now needs the capacity of excision 6 units, if select 1:2:3 combination, needs action 3 times, selects 6 combinations only to need action once.Therefore, select 6 combinations, namely the 4th road electric capacity is best excision capacitor combination.

Sometimes, use single substrategy, the best excision capacitor combination selected is not unique.Such as, the capacitance group of 1:2:3:6:6:6 coding, have 6 road electric capacity, need the capacity of excision 6 units, the excised capacitor combination selected in step S23 is 6 combinations, and 6 combinations comprise the 4th road electric capacity, the 5th road electric capacity and the 6th road electric capacity.In step s 24 which, if uniquely use so that the minimum substrategy for foundation of capacitor switching action in capacitor combination can be dropped into, because the 4th, the 5th or the 6th road electric capacity all only needs action once, cause and then one cannot select best excision capacitor combination.Now, can select to select arbitrarily a road and excise capacitor combination from multiple meeting the combination of substrategy as the best.Also the combination of multiple substrategy can be used.Now, the multiple substrategys for using are needed to distribute priority, the high substrategy of priority is first used to select best excision capacitor combination to obtain the first result from excising capacitor combination, if combine not unique in the first result, then use priority time high substrategy from the first result, select best excision capacitor combination ... by that analogy, until select unique the best excision capacitor combination.Such as, for so that the minimum substrategy assigned highest priority for foundation of capacitor switching action in capacitor combination can be excised, for the substrategy being foundation by the least number of times of switching with electric capacity distributes secondary high priority, for the electric capacity for identical capacity distributes minimum priority with the operating time the longest substrategy for foundation, according to priority order from high to low, above-mentioned three kinds of substrategys are used to screen capacitor combination can be excised, draw unique result when using certain substrategy, then screen end.

In the second embodiment of capacitor switching method of the present invention; due to from first, there is maximum compensation capacity electric capacity; the compensation capacity of each road electric capacity is maximum compensation capacity afterwards; according to the feature of coding; overcompensation capacity between making from one to maximum compensation capacity can realize seamless excision; efficiently avoid switching concussion, protect electric capacity well.Moreover; use the second preset strategy from all resectable capacitor combinations, filter out best excision capacitor combination; by the configuration of the second preset strategy, the concussion of electrical network can be reduced further and/or protect electric capacity better and/or obtain response speed faster.

Fig. 3 is the flow chart of capacitor switching method of the present invention 3rd embodiment, and as shown in Figure 3, in the present embodiment, capacitor switching method comprises the following steps:

S310, according to the best excision capacitor combination switching is carried out to the corresponding capacitance in described capacitor box.

The difference of the present embodiment and capacitor switching method first and second embodiment is, capacity excision function when simultaneously possessing capacity compensation function and overcompensation.First detection of grid is in overcompensation state or undercompensation state, then carries out capacity compensation or capacity excision operation accordingly according to testing result.

Fig. 4 is the logic diagram of capacitor switching device 100 first embodiment of the present invention, and as shown in Figure 4, capacitor switching device 100 comprises:

First detecting unit 10, for detecting the capacity of the electric capacity dropped in current electric grid undercompensation capacity and capacitor box;

First sum unit 11, for by undercompensation capacity and dropped into capacity summation to obtain total capacity;

Capacitor combination computing unit 12 can be dropped into, for the dropped into capacitor combination calculating and can provide described total capacity of falling into a trap from the multichannel electric capacity of capacitor box;

Best input capacitor combination selected cell 13, for selecting best input capacitor combination according to the first preset strategy from described input capacitor combination;

First control unit 14, carries out switching for dropping into capacitor combination according to described the best to the corresponding capacitance in described capacitor box.

Concrete, the first detecting unit 10 detects the under-compensated capacity of current electric grid (namely also needing the compensation capacity for electrical network provides), and the capacity of the electric capacity dropped in capacitance present cabinet (capacity namely compensated).In the present embodiment, capacitor box multichannel electric capacity, every road electric capacity is encoded according to its compensation capacity, and from first electric capacity with maximum compensation capacity, the compensation capacity of each road electric capacity is maximum compensation capacity afterwards.That is, the corresponding a kind of coding of capacitor box, the way of electric capacity and the way of coding can together also can not be identical.From first electric capacity with maximum compensation capacity, the compensation capacity of each road electric capacity is maximum compensation capacity afterwards, and capacitive encoder is as 1:1:1:1,1:2:4:4:, 1:1:2:4,1:2:3:6 and 1:2:3:6:6.Such capacitive encoder has a feature, and the task combination within heap(ed) capacity can both realize.Now identical with the way of coding with the way of electric capacity, 1:2:3:6 is encoded to example, the capacity of its first via electric capacity is 1Kvar, the capacity of the second road electric capacity is 2Kvar, the capacity of the 3rd road electric capacity is the capacity of 3Kvar and the 4th road electric capacity is 6Kvar, heap(ed) capacity is that the arbitrary integer capacity in 6Kvar, 1-6Kvar can both be realized by the combination of 1,2,3 and 6.

The capacity of under-compensated for current electric grid capacity with the electric capacity dropped into is sued for peace by the first sum unit 11, obtains total capacity.For 1:2:3:6, the under-compensated capacity of current electric grid is 4Kvar, and the second road electric capacity in four road electric capacity comes into operation, and the total capacity (namely not dropping into total undercompensation capacity during electric capacity) that both summations draw is 4+2=6Kvar.

Capacitor combination computing unit 12 can be dropped into according to the capacitive encoder of capacitor box and the total capacity that calculates, calculate the combination that the electric capacity of total capacity can be provided in the multichannel electric capacity of capacitor box, can capacitor combination be dropped into.As precedent, the total capacity calculated is 6Kvar, and the capacitive encoder of capacitor box is 1:2:3:6, therefore, it is possible to provide the capacitor combination of 6Kvar to be 1:2:3 and 6 these two kinds, namely simultaneously drop into the first via as the 3rd tunnel or only drop into the 6th tunnel.

Store the first preset strategy in capacitor switching device 100, the best capacitor combination selected cell 13 that drops into will select best input capacitor combination from the dropped into capacitor combination calculated according to the first preset strategy.First preset strategy comprises one or more substrategy following: with the minimum substrategy for foundation of the capacitance of synchronization switching, with the minimum substrategy for foundation of the electric capacity quantity participating in work after switching, with electric capacity by the least number of times of the switching substrategy that is foundation, drop into the minimum substrategy for foundation of capacitor switching action in capacitor combination for the electric capacity of identical capacity with the operating time the shortest substrategy for foundation and with described.User can according to the actual needs, select arbitrary substrategy to combine.

When using substrategy for foundation minimum with the capacitance of synchronization switching, electrical network can be made to shake and to minimize.As precedent, the dropped into capacitor combination selected is 1:2:3 and 6, and the second road electric capacity drops into.If select 1:2:3 combination, then need successively to drop into the first via and the 3rd road electric capacity, electrical network synchronization needs to bear the concussion that 3 unit capacitys cause.If select 6 combinations, then need excision second road electric capacity, drop into the 4th road electric capacity, electrical network synchronization need bear the concussion that 6 specific capacitances cause.Therefore, according to the minimum substrategy for foundation of the capacitance of synchronization switching, selection 1:2:3 is combined as best input capacitor combination.

When use to participate in the minimum substrategy for foundation of the electric capacity quantity of work after with switching time, the multiplex circuit in capacitor box can be protected well.As precedent, the dropped into capacitor combination selected is 1:2:3 and 6, and the second road electric capacity drops into.If select 1:2:3 combination, then need 3 electric capacity work, mean the first to the 3rd tunnel totally 3 electric capacity subject loss.If select 6 combinations, then need excision second road electric capacity, drop into the 4th road electric capacity, only have the 4th road electric capacity in loss.Therefore, according to the minimum substrategy for foundation of the electric capacity quantity participating in work after switching, selection 6 is combined as best input capacitor combination.

Switching frequency due to electric capacity is limited, therefore uses with electric capacity by the substrategy that the least number of times of switching is foundation, can protect the multiplex circuit in capacitor box well.Its ventilative number of times once, will increase once by the every switching of each electric capacity in static var compensator.As precedent, the dropped into capacitor combination selected is 1:2:3 and 6, and the second road electric capacity drops into.First via capacitor switching 1 time, the 3rd road capacitor switching 4 times, the 4th road capacitor switching 2 times.Therefore, according to electric capacity by the substrategy that the least number of times of switching is foundation, selection 6 is combined as and best drops into capacitor combination.Again such as, capacitance group be encoded to 1:2:3:4:4:4, now need the capacity compensating 4Kvar again, 4th road capacitor switching 5 times, the 5th road capacitor switching 4 times, the 6th road capacitor switching 3 times, their capacity is 4, is criterion according to switching frequency, then select input the 6th tunnel.

When using the substrategy for foundation the shortest in the operating time of the electric capacity for identical capacity, will preferentially excise the electric capacity of longevity of service, the electric capacity that the time of preferentially devoting oneself to work is short, electric capacity can be protected well.Capacitance group be encoded to 1:2:3:4:4:4, now need the capacity compensating 4Kvar again, the time that the 4th, the 5th and the 6th road electric capacity has worked is respectively 10,20 and 30 hours, as the capacity of 4 units need be dropped into, so preferentially drop into the 4th road electric capacity.

Sometimes, use single substrategy, it is not unique that the best selected drops into capacitor combination.Such as, the capacitance group of 1:2:3:6:6:6 coding, have 6 road electric capacity, need the capacity of input 6 units, the dropped into capacitor combination selected in step S13 is 6 combinations, and 6 combinations comprise the 4th road electric capacity, the 5th road electric capacity and the 6th road electric capacity.If uniquely use can drop into the minimum substrategy for foundation of capacitor switching action in capacitor combination, and input the 4th, the 5th or the 6th road electric capacity all only needs action once, causes and then one cannot select best input capacitor combination.Now, can select to select arbitrarily a road and drop into capacitor combination from multiple meeting the combination of substrategy as the best.Also the combination of multiple substrategy can be used.Now, the multiple substrategys for using are needed to distribute priority, the high substrategy of priority is first used to select the best capacitor combination that drops into obtain the first result from dropping into capacitor combination, if combine not unique in the first result, then use priority time high substrategy from the first result, select best input capacitor combination ... by that analogy, until select unique the best to drop into capacitor combination.Such as, for so that the minimum substrategy assigned highest priority for foundation of capacitor switching action in capacitor combination can be dropped into, for the substrategy being foundation by the least number of times of switching with electric capacity distributes secondary high priority, for the electric capacity for identical capacity distributes minimum priority with the operating time the shortest substrategy for foundation, according to priority order from high to low, above-mentioned three kinds of substrategys are used to screen capacitor combination can be dropped into, draw unique result when using certain substrategy, then screen end.

Finally, the first control unit 14 carries out switching according to the best input capacitor combination selected to the corresponding capacitance in capacitor box.

In the first embodiment of capacitor switching device of the present invention; due to from first, there is maximum compensation capacity electric capacity; the compensation capacity of each road electric capacity is maximum compensation capacity afterwards; according to the feature of coding; the idle of arbitrary target value between making from one to maximum compensation capacity can realize seamless compensation; also efficiently avoid the switching concussion of mending and causing simultaneously, protect electric capacity well.Moreover; use the first preset strategy from all capacitor combinations dropped into, filter out best input capacitor combination; by the configuration of the first preset strategy, the concussion of electrical network can be reduced further and/or protect electric capacity better and/or obtain response speed faster.

Fig. 5 is the logic diagram of capacitor switching device 100 second embodiment of the present invention, and as shown in Figure 5, in the present embodiment, capacitor switching device 100 comprises:

Second detecting unit 20, for detecting the capacity of the electric capacity excised in current electric grid overcompensation capacity and capacitor box;

Second sum unit 21, for by overcompensation capacity and excised capacity summation to obtain total capacity;

Capacitor combination computing unit 22 can be excised, for the excised capacitor combination calculating and can provide described total capacity of falling into a trap from the multichannel electric capacity of capacitor box;

Best excision capacitor combination selected cell 23, for selecting best excision capacitor combination according to the second preset strategy from described excision capacitor combination;

Second control unit 24, for carrying out switching according to described the best excision capacitor combination to the corresponding capacitance in described capacitor box.

Different from capacitor switching device 100 first embodiment of the present invention, in the present embodiment, main what pay close attention to is the situation of electrical network overcompensation.

Second detecting unit 20 detects the capacity (the unnecessary electric capacity namely dropped into) of current electric grid overcompensation, and the capacity of the electric capacity excised in capacitance present cabinet (being namely in the capacity of the electric capacity of excision state).In the present embodiment, capacitor box comprises multichannel electric capacity, and every road electric capacity is encoded according to its compensation capacity, and from first electric capacity with maximum compensation capacity, the compensation capacity of each road electric capacity is maximum compensation capacity afterwards.That is, the corresponding a kind of coding of capacitor box, the way of electric capacity and the way of coding can together also can not be identical.From first electric capacity with maximum compensation capacity, the compensation capacity of each road electric capacity is maximum compensation capacity afterwards, capacitive encoder is as 1:1:1:1,1:2:4:4:, 1:1:2:4,1:2:3:6 and 1:2:3:6:6, such capacitive encoder has a feature, and the task compensation capacity within heap(ed) capacity can pass through the incompatible realization of capacitance group.Now identical with the way of coding with the way of electric capacity, 1:2:3:6 is encoded to example, the capacity of its first via electric capacity is 1Kvar, the capacity of the second road electric capacity is 2Kvar, the capacity of the 3rd road electric capacity is the capacity of 3Kvar and the 4th road electric capacity is 6Kvar, heap(ed) capacity is that the arbitrary integer capacity in 6Kvar, 1-6Kvar can both be realized by the combination of 1,2,3 and 6.

The capacity of the capacity of current electric grid overcompensation with the electric capacity excised is sued for peace by the second sum unit 21, obtains total capacity.For 1:2:3:6, the capacity of current electric grid overcompensation is 4Kvar, and the second road electric capacity in four road electric capacity is cut (being namely in excision state), and the total capacity that both summations draw is 4+2=6Kvar.

Capacitor combination computing unit 22 can be excised according to the capacitive encoder of capacitor box and the total capacity that calculates, calculate the combination that the electric capacity of total capacity can be provided in the multichannel electric capacity of capacitor box, can capacitor combination be excised.As precedent, the total capacity calculated in step S22 is 6Kvar, the capacitive encoder of capacitor box is 1:2:3:6, therefore, the capacitor combination of 6Kvar can be provided to be 1:2:3 and 6 these two kinds (can capacitor combination be excised), namely to make the first via all be in excision state as the 3rd tunnel or only make the 6th tunnel be in excision state simultaneously.

Capacitor switching device 100 stores the second preset strategy, and best excision capacitor combination selected cell 23 will select best excision capacitor combination from the excised capacitor combination calculated according to the second preset strategy.Second presets plan comprises one or more substrategy following: with the minimum substrategy for foundation of the capacitance of synchronization switching, with the minimum substrategy for foundation of the electric capacity quantity participating in work after switching, with electric capacity by the least number of times of the switching substrategy that is foundation, for the electric capacity of identical capacity with the operating time the longest substrategy for foundation and so that the minimum substrategy for foundation of capacitor switching action in capacitor combination can be excised.User can according to the actual needs, select arbitrary substrategy to combine.

When using substrategy for foundation minimum with the capacitance of synchronization switching, electrical network can be made to shake and to minimize.As precedent, the dropped into capacitor combination selected is 1:2:3 and 6, and the second road electric capacity has been in excision state.If select 1:2:3 combination, then need successively the excision first via and the 3rd road electric capacity, electrical network synchronization needs to bear the concussion that 3 unit capacitys cause.If select 6 combinations, then need input second road electric capacity, then excise the 4th road electric capacity, electrical network synchronization need bear the concussion that 6 specific capacitances cause.Therefore, according to the minimum substrategy for foundation of the capacitance of synchronization switching, selection 1:2:3 is combined as best excision capacitor combination.

When use to participate in the minimum substrategy for foundation of the electric capacity quantity of work after with switching time, the multiplex circuit in capacitor box can be protected well.As precedent, the excised capacitor combination selected is 1:2:3 and 6, and the second road electric capacity has been in excision state.If select 1:2:3 combination, then need the 4th road electric capacity work, namely only have 1 electric capacity subject loss.If select 6 combinations, then need input second road electric capacity, excision the 4th road electric capacity, the first via, the second tunnel and the 3rd road electric capacity are all in work, bear loss.Therefore, according to the minimum substrategy for foundation of the electric capacity quantity participating in work after switching, selection 1:2:3 is combined as best excision capacitor combination.

Switching frequency due to electric capacity is limited, therefore uses with electric capacity by the substrategy that the least number of times of switching is foundation, can protect the multiplex circuit in capacitor box well.Its ventilative number of times once, will increase once by the every switching of each electric capacity in static var compensator.As precedent, the excised capacitor combination selected is 1:2:3 and 6, and the second road electric capacity excises.First via capacitor switching 1 time, the second road capacitor switching 1 time, the 3rd road capacitor switching 4 times, the 4th road capacitor switching 2 times.Therefore, according to electric capacity by the substrategy that the least number of times of switching is foundation, selection 6 is combined as and best drops into capacitor combination.Again such as, capacitance group be encoded to 1:2:3:4:4:4, the capacity of existing overcompensation 4Kvar, 4th road capacitor switching 5 times, the 5th road capacitor switching 4 times, the 6th road capacitor switching 3 times, their capacity is 4, is criterion according to switching frequency, then select input the 6th road electric capacity.

Sometimes, use single substrategy, the best excision capacitor combination selected is not unique.Such as, the capacitance group of 1:2:3:6:6:6 coding, have 6 road electric capacity, need the capacity of excision 6 units, the excised capacitor combination selected is 6 combinations, and 6 combinations comprise the 4th road electric capacity, the 5th road electric capacity and the 6th road electric capacity.If uniquely use so that the minimum substrategy for foundation of capacitor switching action in capacitor combination can be dropped into, because the 4th, the 5th or the 6th road electric capacity all only needs action once, cause and then one cannot select best excision capacitor combination.Now, can select to select arbitrarily a road and excise capacitor combination from multiple meeting the combination of substrategy as the best.Also the combination of multiple substrategy can be used.Now, the multiple substrategys for using are needed to distribute priority, the high substrategy of priority is first used to select best excision capacitor combination to obtain the first result from excising capacitor combination, if combine not unique in the first result, then use priority time high substrategy from the first result, select best excision capacitor combination ... by that analogy, until select unique the best excision capacitor combination.Such as, for so that the minimum substrategy assigned highest priority for foundation of capacitor switching action in capacitor combination can be excised, for the substrategy being foundation by the least number of times of switching with electric capacity distributes secondary high priority, for the electric capacity for identical capacity distributes minimum priority with the operating time the longest substrategy for foundation, according to priority order from high to low, above-mentioned three kinds of substrategys are used to screen capacitor combination can be excised, draw unique result when using certain substrategy, then screen end.When to employ after all substrategys result and be still unique, then acquiescence chooses one as and bestly drops into capacitor combination.

In capacitor switching device 100 second embodiment of the present invention; due to from first, there is maximum compensation capacity electric capacity; the compensation capacity of each road electric capacity is maximum compensation capacity afterwards; according to the feature of coding; overcompensation capacity between making from one to maximum compensation capacity can realize seamless excision; efficiently avoid switching concussion, protect electric capacity well.Moreover; use the second preset strategy from all resectable capacitor combinations, filter out best excision capacitor combination; by the configuration of the second preset strategy, the concussion of electrical network can be reduced further and/or protect electric capacity better and/or obtain response speed faster.

Fig. 6 is the logic diagram of capacitor switching device 100 the 3rd embodiment of the present invention, and as shown in Figure 6, in the present embodiment, capacitor switching device 100 comprises:

Judging unit 30, for judging that the state of current electric grid is undercompensation state or overcompensation state;

First detecting unit 10, for when current electric grid is undercompensation state, detects the capacity of the electric capacity dropped in current electric grid undercompensation capacity and capacitor box;

First control unit 14, carries out switching for dropping into capacitor combination according to described the best to the corresponding capacitance in described capacitor box;

Second detecting unit 20, for when current electric grid state is overcompensation state, detects the capacity of the electric capacity excised in current electric grid overcompensation capacity and capacitor box;

The difference of the present embodiment and capacitor switching device 100 first and second embodiment is, capacity excision function when simultaneously possessing capacity compensation function and overcompensation.First detection of grid is in overcompensation state or undercompensation state, then carries out capacity compensation or capacity excision operation accordingly according to testing result.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within right of the present invention.

Claims

1. a capacitor switching method, is characterized in that, comprises the following steps:

2. capacitor switching method according to claim 1, it is characterized in that, described capacitor box comprises multichannel electric capacity, and every road electric capacity is encoded according to its compensation capacity, from first electric capacity with maximum compensation capacity, the compensation capacity of each road electric capacity is maximum compensation capacity afterwards.

3. capacitor switching method according to claim 1, is characterized in that, described first presets plan comprises one or more substrategy following:

With the minimum substrategy for foundation of electrical network concussion;

To participate in the substrategy that the electric capacity minimum number of switching is foundation;

With response speed the soonest for the substrategy of foundation.

4. a capacitor switching method, is characterized in that, comprises the following steps:

5. capacitor switching method according to claim 4, it is characterized in that, described capacitor box comprises multichannel electric capacity, and every road electric capacity is encoded according to its compensation capacity, from first electric capacity with maximum compensation capacity, the compensation capacity of each road electric capacity is maximum compensation capacity afterwards.

6. capacitor switching method according to claim 4, is characterized in that, described second preset strategy comprises one or more substrategy following:

With the minimum substrategy for foundation of electrical network concussion;

With response speed the soonest for the substrategy of foundation.

7. a capacitor switching method, is characterized in that, comprises the following steps:

8. a capacitor switching device, is characterized in that, comprising:

First detecting unit (10), for detecting the capacity of the electric capacity dropped in current electric grid undercompensation capacity and capacitor box;

First sum unit (11), for by undercompensation capacity and dropped into capacity summation to obtain total capacity;

Capacitor combination computing unit (12) can be dropped into, for the dropped into capacitor combination calculating and can provide described total capacity of falling into a trap from the multichannel electric capacity of capacitor box;

Best input capacitor combination selected cell (13), for selecting best input capacitor combination according to the first preset strategy from described input capacitor combination;

First control unit (14), carries out switching for dropping into capacitor combination according to described the best to the corresponding capacitance in described capacitor box.

9. a capacitor switching device, is characterized in that, comprising:

Second detecting unit (20), for detecting the capacity of the electric capacity excised in current electric grid overcompensation capacity and capacitor box;

Second sum unit (21), for by overcompensation capacity and excised capacity summation to obtain total capacity;

Capacitor combination computing unit (22) can be excised, for the excised capacitor combination calculating and can provide described total capacity of falling into a trap from the multichannel electric capacity of capacitor box;

Best excision capacitor combination selected cell (23), for selecting best excision capacitor combination according to the second preset strategy from described excision capacitor combination;

Second control unit (24), for carrying out switching according to described the best excision capacitor combination to the corresponding capacitance in described capacitor box.

10. a capacitor switching device, is characterized in that, comprising:

Judging unit (30), for judging that the state of current electric grid is undercompensation state or overcompensation state;

First detecting unit (10), for when current electric grid is undercompensation state, detects the capacity of the electric capacity dropped in current electric grid undercompensation capacity and capacitor box;

First control unit (14), carries out switching for dropping into capacitor combination according to described the best to the corresponding capacitance in described capacitor box;

Second detecting unit (20), for when current electric grid state is overcompensation state, detects the capacity of the electric capacity excised in current electric grid overcompensation capacity and capacitor box;