CN101741097B - Distribution transformer capacity sequence grade optimizing method - Google Patents

Abstract

The invention provides a distribution transformer capacity sequence grade optimizing method, belonging to the power system distribution transformer field. Firstly grouping calculation is started at minimum capacity grade sequence according to rated capacity specified by related existing standards, the calculation is stopped until an obvious inflection point appears on transformer average comprehensive damage curve, the capacity grade at the inflection point is the optimal capacity grade with minimum average comprehensive damage of the capacity grade sequence group, then capacity grade sequence grouping is continued by taking the next capacity grade as an initial point, optimizing calculation is carried out sequentially according to the steps until the inflection point appears, and the optimal capacity grade with minimum average comprehensive damage of the group is selected. The process is repeated, and finally optimized new capacity grade sequence is formed. Initial investment cost of distribution transformer can be effectively reduced, thus being beneficial to storage and dispatching of emergency goods and materials and running goods and materials of power system, and operating cost is reduced and the overall size advantage is developed, thus being beneficial to standardization and normalization of major equipment of distribution power system.

Description

A kind of distribution transformer capacity sequence grade optimizing method

Technical field

The present invention relates to a kind of distribution transformer capacity sequence grade optimizing method, belong to electric power system distribution transformer field.

Background technology

During 1998～2000, extensive upgrading urban and rural power grids Zhong， China has adopted S9 type distribution transformer in a large number, approximately occupies 50%～60% of in-service distribution transformer in system.In recent years, by employing new technology, new material, new construction, new technology, the performance level of domestic novel energy-conserving distribution transformer constantly promotes, and S11 type distribution transformer becomes the main product in newly-built and improvement project.The procurement price of distribution transformer fluctuates because purchasing scope is big or small, and larger with capacity same specification product purchasing quantity, procurement price is lower.

According to standard GB/T/T6451-2008 < < oil-immersed power transformer technical parameter with require > >, GB/T10228-2008 < < dry-type power transformer technical parameter and the regulation that requires the relevant criterion such as > > and machinery industry standard JB/T3837 < < transformer ' s type product type preparation method > >, the range of capacity of 10kV level S11 type Three-phase oil immersion type double winding non-excitation voltage regulation distribution transformer is 30～1600kVA, totally 17 capacitance grades, the range of capacity of 10kV level SCB10 type 3-phase dry type non-excitation voltage regulation distribution transformer is 30～2500kVA, totally 18 capacitance grades.Distribution transformer capacity sequence grade is more, is unfavorable for deposit and the scheduling of electric network emergency goods and materials and operation goods and materials, is unfavorable for reducing power grid operation cost and performance overall size advantage, is equally also unfavorable for standardization and the standardization of power distribution network capital equipment.Table 1 is the capacitance grade Data Comparison situation in capacitance grade sequence before and after 10kV transformer capacity rate sequence is optimized.

Table 110kV transformer capacity rate sequence contrasts before and after optimizing

By table 1 data, can be found out, by adopting distribution transformer capacity sequence grade optimizing method to be optimized, no matter be single-phase transformer or three-phase transformer, no matter be oil-filled transformer or dry-type transformer, both met and there is preferably overall energy-saving effect, meet again load and growth requirement thereof, capacitance grade quantity in all kinds of transformer capacity rate sequences is by 12～18, be reduced to 4～5, be conducive to deposit and the scheduling of electric network emergency goods and materials and operation goods and materials, reduce power grid operation cost and performance overall size advantage, equally also be beneficial to standardization and the standardization of power distribution network capital equipment.

Summary of the invention

The object of this invention is to provide a kind of distribution transformer capacity sequence grade optimizing method.The load of the most distribution transformers in urban and rural power grids is not evenly constant, but presents typical daily load variation characteristic or seaonal load feature.Peak time platform district distribution transformer is in fully loaded or overlond running state, and low ebb platform in period district distribution transformer is substantially in zero load or light condition.Distribution transformer capacity configuration is not that just in time to meet peak load demand be exactly most economical, and need to be optimized calculating according to distribution transformer implement body technical performance parameter, reasonable disposition.

Distribution transformer self has resistance and inductance, as long as charging operation exists electromagnetic change, just has own loss.The running wastage of distribution transformer, in China's power distribution network, especially occupies suitable proportion (approximately 30%～70%) in vast Rural Power Distribution Network, becomes the important component part of whole losses of distribution network.Emphasis is considered the power transformation operation cost of transformer self, take and meet workload demand and saving energy and decreasing loss is principle, carry out the optimization of distribution transformer capacity rate sequence, so that deposit and the scheduling of electric network emergency goods and materials and operation goods and materials, reduce power grid operation cost, bring into play overall size advantage, effectively promote standardization and the standardization process of power distribution network capital equipment.

The present invention proposes a kind of distribution transformer capacity sequence grade optimizing method, it is characterized in that:

In the situation of same each Rate of average load of load, close capacitance grade sequence is optimized, according to following formula, be optimized calculating:

${\mathrm{\&beta;}}_{\mathrm{ik}}=\frac{S_n}{S_i}\&times;{\mathrm{\&beta;}}_{\mathrm{nk}}$ (k=1 wherein, 2,3 ...) (1)

$\stackrel{\&OverBar;}{P_{\mathrm{ik}}}=\mathrm{AVERAGE}[P_{0i}+K_t{{\mathrm{\&beta;}}_{\mathrm{ik}}}^2{P}_{\mathrm{ki}}+C(Q_{0i}+K_t{{\mathrm{\&beta;}}_{\mathrm{ik}}}^2{Q}_{\mathrm{ki}})]---\left(2\right)$

In formula (1) and (2):

AVERAGE-mean value calculation;

K-load factor series number;

Q _0i-distribution transformer capacity is S _ispecified unloaded reactive loss;

S _nselected reference capacity in-grouping;

S _ii in-grouping is waited level capacity;

β _ik-distribution transformer capacity is S _itime relative datum capacity S _nconversion load factor under each load factor;

β nk-distribution transformer capacity reference capacity S _ntime load factor;

rate of average load β in the combination of-distribution transformer capacity sequence _nkunder the average composite loss of transformer;

P _0i-distribution transformer capacity is S _ispecified unloaded active loss, unit is: kW;

K _t-fluctuation of load loss factor, generally gets 1.05;

P _ki-distribution transformer capacity is S _inominal load active loss, unit is: kW;

Q _ki-distribution transformer capacity is S _ispecified unloaded reactive loss, unit is: kvar;

C-idle Economic Equivalent, kW/kvar; Idle Economic Equivalent gets 0.1 herein;

Distribution transformer for certain model carries out capacitance grade sequence optimisation, first should from minimum capacity grade, start grouping according to the rated capacity of relevant existing standard defined and calculate:

Grouping is exactly from the minimum capacity grade in normal capacity sequence, general 4～6 is one group, if found in calculating, until flex point does not appear in the average composite loss curve of heap(ed) capacity grade in grouping yet, can continue to increase the capacitance grade number in grouping.Circular can decompose (2) formula:

${\mathrm{\&beta;}}_i=\frac{S_n}{S_i}\&times;{\mathrm{\&beta;}}_n$

Wherein:

S _nfor the reference capacity capacity in grouping, the load factor of establishing reference capacity is β _n;

S _ifor i level capacity such as grade in grouping, β _ifor the load factor of same load conversion to this capacitance grade;

P _i1＝P _0i+K _tβ _i1 ²P _ki+C(Q _0i+K _tβ _i1 ²Q _ki)

P _i2＝P _0i+K _tβ _i2 ²P _ki+C(Q _0i+K _tβ _i2 ²Q _ki)

：

：

：

$\stackrel{\&OverBar;}{P_i}=\mathrm{AVERAGE}\left(P_{\mathrm{ik}}\right),$ K=1 wherein, 2,3

According to the average composite loss under each each load factor of group capacity grade, make the average composite loss curve of each group capacity grade, abscissa is capacitance grade, the kVA of unit; Ordinate is average composite loss, and unit is kW.If there is obvious flex point in average composite loss curve, the capacitance grade that flex point occurs is the optimum capacity grade of the average composite loss minimum of this group capacity rate sequence, next capacitance grade of flex point of take is again starting point, proceed capacitance grade sequence of packets, according to above-mentioned steps, optimize successively calculating, until there is flex point, select the optimum capacity grade that this organizes average composite loss minimum; Then according to above grouping and optimized calculation method, until calculate the rated capacity of maximum existing standard defined, the new capacitance grade sequence after the flex point capacitance grade compositional optimization retaining in each group.

Wherein, said method is refined as to following steps:

(1) normal capacity grade is divided into groups from low to high, take 4～6 capacitance grades as one group, first determine first group, take lowest capacity grade as reference capacity grade, can calculate the payload under its different loads rate, wherein S according to formula (3) formula _nfor selected reference capacity in grouping; β _nkfor distribution transformer capacity reference capacity S _ntime load factor, k=1,2,3 S _sjnkfor the actual load size under reference capacity grade different loads rate:

S _sjnk＝β _nkS _n （3）

(2) according to (4) formula, calculate composite loss and the mean value thereof under different loads rate under reference capacity:

$\stackrel{\&OverBar;}{P_{\mathrm{nk}}}=\mathrm{AVERAGE}[P_{0n}+K_t{{\mathrm{\&beta;}}_{\mathrm{nk}}}^2{P}_{\mathrm{kn}}+C(Q_{0n}+K_t{{\mathrm{\&beta;}}_{\mathrm{nk}}}^2{Q}_{\mathrm{kn}})]---\left(4\right)$

Wherein:

Q _0n-distribution transformer reference capacity S _nspecified unloaded reactive loss;

reference capacity grade Rate of average load β in the combination of-distribution transformer capacity sequence _nkunder average composite loss;

P _0n-distribution transformer reference capacity S _nspecified unloaded active loss, unit is: kW;

K _t-fluctuation of load loss factor, generally gets 1.05;

P _kn-distribution transformer reference capacity S _nnominal load active loss, unit is: kW;

Q _kn-distribution transformer reference capacity S _nspecified unloaded reactive loss, unit is: kvar;

C-idle Economic Equivalent, kW/kvar; Idle Economic Equivalent gets 0.1 herein;

(3) calculate in grouping than the conversion load factor of the high capacitance grade of reference capacity grade, establishing in grouping is S than the capacity of the high grade of reference capacity grade _n+1, the conversion load factor β of this capacitance grade relative datum capacitance grade _(n+1)k can calculate according to (5) formula:

${\mathrm{\&beta;}}_{(n+1)k}=\frac{S_{\mathrm{sjnk}}}{S_{n+1}}---\left(5\right)$

(4) according to (6) formula calculate in grouping than composite loss and mean value thereof under the high capacitance grade conversion load factor of reference capacity grade:

$\stackrel{\&OverBar;}{P_{(n+1)k}}=\mathrm{AVERAGE}[P_{0(n+1)}+K_t{{\mathrm{\&beta;}}_{(n+1)k}}^2{P}_{k(n+1)}+C(Q_{0(n+1)}+K_t{{\mathrm{\&beta;}}_{(n+1)k}}^2{Q}_{k(n+1)})]---\left(6\right)$

Wherein:

Q _{0 (n+1})-than the high first-class level capacity S of distribution transformer reference capacity _n+1specified unloaded reactive loss;

in the combination of-distribution transformer capacity sequence, than the high capacitance grade of reference capacity, convert load factor β _{(n+1) k}under composite loss mean value;

P _{0 (n+1)}-than the high first-class level capacity S of distribution transformer reference capacity _n+1specified unloaded active loss, unit is: kW;

P _{k (n+1)}-than the high first-class level capacity S of distribution transformer reference capacity _n+1nominal load active loss, unit is: kW;

Q _{k (n+1)}-than the high first-class level capacity S of distribution transformer reference capacity _n+1specified unloaded reactive loss, unit is: kvar;

(5) calculate in grouping than the reference capacity grade conversion load factor of a high capacitance grade again, establish in grouping than reference capacity grade again the capacity of a high grade be S _n+2, the conversion load factor of this capacitance grade relative datum capacitance grade can be calculated according to (7):

${\mathrm{\&beta;}}_{(n+2)k}=\frac{S_{\mathrm{sjnk}}}{S_{n+2}}---\left(7\right)$

(6) according to (8) formula calculate in grouping than reference capacity grade composite loss and the mean value thereof under a high capacitance grade conversion load factor again:

$\stackrel{\&OverBar;}{P_{(n+2)k}}=\mathrm{AVERAGE}[P_{0(n+2)}+K_t{{\mathrm{\&beta;}}_{(n+2)k}}^2{P}_{k(n+2)}+C(Q_{0(n+2)}+K_t{{\mathrm{\&beta;}}_{(n+2)k}}^2{Q}_{k(n+2)})]---\left(8\right)$

Wherein:

Q _{0 (n+2)}-than distribution transformer reference capacity high first-class level capacity S again _n+2specified unloaded reactive loss;

in-distribution transformer capacity sequence combination than a reference capacity high capacitance grade conversion load factor β again _{(n+2) k}under combine

Close loss mean value;

P _{0 (n+2)}-than distribution transformer reference capacity high first-class level capacity S again _n+2specified unloaded active loss, unit is: kW;

P _{k (n+2)}-than distribution transformer reference capacity high first-class level capacity S again _n+2nominal load active loss, unit is: kW;

Q _{k (n+1)}-than the high first-class level capacity S of distribution transformer reference capacity _n+2specified unloaded reactive loss, unit is: kvar;

(7) calculate until flex point appears in the composite loss mean value in this grouping successively the capacitance grade that the optimization that capacitance grade corresponding to selected flex point place is this grouping retains afterwards;

(8) take the next capacitance grade of flex point as new reference capacity, again divide into groups from low to high, first calculate the payload under reference capacity grade different loads rate;

(9) repeating step (2)～(8), enter again next circulation, until the rated capacity rating calculation of maximum described existing standard defined is complete, if last pool-size grade does not have flex point to occur, the optimizing capacity grade that the rated capacity grade of determining maximum described existing standard defined is this group;

(10) calculate each capacitance grade that divides into groups to retain and formed new capacitance grade sequence, be optimizing capacity rate sequence.

The invention has the beneficial effects as follows: the capacitance grade sequence of existing relevant distribution transformer technical standard defined is more, same specification distribution transformer product is not easy to the buying of formation scale, and purchase cost is higher.Distribution transformer capacity rate sequence based on workload demand and saving energy and decreasing loss and after optimizing, be only generally 3～5 capacitance grades, with respect to original 12～18 capacitance grade sequences, very easily formation scale is purchased, and can effectively reduce the initial outlay cost of distribution transformer.

Accompanying drawing explanation

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

Fig. 1 is the average composite loss comparison diagram of same load under 30kVA and close capacitance grade and conversion load factor;

Fig. 2 is the average composite loss comparison diagram of same load under 80kVA and close capacitance grade and conversion load factor;

Fig. 3 is the average composite loss comparison diagram of same load under 200kVA and close capacitance grade and conversion load factor;

Fig. 4 is the average composite loss comparison diagram of same load under 500kVA and close capacitance grade and conversion load factor;

Fig. 5 is the average composite loss comparison diagram of same load under 1000kVA and close capacitance grade and conversion load factor.

Embodiment

Be the preferred embodiments of the present invention below, technical scheme the present invention being realized below in conjunction with this accompanying drawing is described further.

Fig. 1 is the average composite loss comparison diagram of same load under 30kVA and close capacitance grade and conversion load factor; A in Fig. 1, B, C, D, E point are the average composite loss that in the first grouping, capacity is respectively 30kVA, 50kVA, 63kVA, 80kVA, 100kVA, the average composite loss that wherein capacity is 50kVA is minimum, in figure, show as B point, be this and organize average composite loss point of inflexion on a curve.

Fig. 2 is the average composite loss comparison diagram of same load under 80kVA and close capacitance grade and conversion load factor; A in Fig. 2, B, C, D, E point are the average composite loss that in the second grouping, capacity is respectively 63kVA, 80kVA, 100kVA, 125kVA, 160kVA, the average composite loss that wherein capacity is 100kVA is minimum, in figure, show as C point, be this and organize average composite loss point of inflexion on a curve.

Fig. 3 is the average composite loss comparison diagram of same load under 200kVA and close capacitance grade and conversion load factor; A in Fig. 3, B, C, D, E point are the average composite loss that in the 3rd grouping, capacity is respectively 125kVA, 160kVA, 200kVA, 250kVA, 315kVA, the average composite loss that wherein capacity is 250kVA is minimum, in figure, show as D point, be this and organize average composite loss point of inflexion on a curve.

Fig. 4 is the average composite loss comparison diagram of same load under 500kVA and close capacitance grade and conversion load factor; A in Fig. 4, B, C, D point are the average composite loss that in the 4th grouping, capacity is respectively 315kVA, 400kVA, 500kVA, 630kVA, 800kVA, the average composite loss that wherein capacity is 630kVA is minimum, in figure, show as D point, be this and organize average composite loss point of inflexion on a curve.

Fig. 5 is the average composite loss comparison diagram of same load under 1000kVA and close capacitance grade and conversion load factor.A in Fig. 5, B, C, D point are the average composite loss that in the 5th grouping, capacity is respectively 800kVA, 1000kVA, 1250,1600kVA, capacity is that the average composite loss of 1600kVA is minimum, in figure, show as D point, but not that this organizes average composite loss point of inflexion on a curve, 1600kVA has been the peak capacity grade of stipulating in 10kV level S11 type Three-phase oil immersion type double winding non-excitation voltage regulation distribution transformer technical standard, and selecting 1600kVA is the optimum capacitance grade of this group.

The S11 type Three-phase oil immersion type double winding non-excitation voltage regulation distribution transformer of take is example, the range of capacity of 10kV level S11 type Three-phase oil immersion type double winding non-excitation voltage regulation distribution transformer is 30～1600kVA, totally 17 capacitance grades, its technical performance parameter is specifically as shown in table 2.

Table 2S11 type Three-phase oil immersion type double winding non-excitation voltage regulation distribution transformer technical performance parameter

According to table 2S11 type Three-phase oil immersion type double winding non-excitation voltage regulation distribution transformer performance parameter, calculate for same load the composite loss situation under different Rate of average loads.

First take 30kVA as reference capacity grade, the composite loss of same load under 30kVA and close capacitance grade and conversion load factor is as shown in table 3.

The composite loss of the same load of table 3 under 30kVA and close capacitance grade and conversion load factor

Table 3 is the concrete calculated data of the first grouping, and Fig. 1 is the average composite loss curve under each rated capacity in the first grouping.By table 3 data and Fig. 1 comparable situation, can be found out, with respect to 30kVA benchmark rated capacity, from overall energy-saving effect and satisfied load and growth requirement consideration thereof, 50kVA is better than other capacitance grades.

Take 63kVA as reference capacity grade again, and the composite loss of same load under 63kVA and close capacitance grade and conversion load factor is as shown in table 4.

The composite loss of the same load of table 4 under 63kVA and close capacitance grade and conversion load factor

Table 4 is the concrete calculated data of the second grouping, and Fig. 2 is the average composite loss curve under each rated capacity in the second grouping.By table 4 data and Fig. 2 comparable situation, can be found out, with respect to benchmark 63kVA rated capacity, from overall energy-saving effect and satisfied load and growth requirement consideration thereof, 100kVA is better than other capacitance grades.

Take 125kVA as reference capacity grade, and the composite loss of same load under 125kVA and close capacitance grade and conversion load factor is as shown in table 5.

The composite loss of the same load of table 5 under 125kVA and close capacitance grade and conversion load factor

Table 5 is the concrete calculated data of the 3rd grouping, and Fig. 3 is the average composite loss curve under each rated capacity in the 3rd grouping.By table 5 data and Fig. 3 comparable situation, can be found out, with respect to 125kVA benchmark rated capacity, from overall energy-saving effect and satisfied load and growth requirement consideration thereof, 250kVA is better than other capacitance grades.

Take 315kVA as reference capacity grade, and the composite loss of same load under 315kVA and close capacitance grade and conversion load factor is as shown in table 6.

The composite loss of the same load of table 6 under 315kVA and close capacitance grade and conversion load factor

Table 6 is the concrete calculated data of the 4th grouping, and Fig. 4 is the average composite loss curve under each rated capacity in the 4th grouping.By table 6 data and Fig. 4 comparable situation, can be found out, with respect to 315kVA benchmark rated capacity, from overall energy-saving effect and satisfied load and growth requirement consideration thereof, 630kVA is better than other capacitance grades.

Take 800kVA as reference capacity grade, and the composite loss of same load under 800kVA and close capacitance grade and conversion load factor is as shown in table 7.

The composite loss of the same load of table 7 under 800kVA and close capacitance grade and conversion load factor

Table 7 is the concrete calculated data of the 5th grouping, and Fig. 5 is the average composite loss curve under each rated capacity in the 5th grouping.By table 7 data and Fig. 5 comparable situation, can be found out, with respect to 800kVA benchmark rated capacity, from overall energy-saving effect and satisfied load and growth requirement consideration thereof, 1600kVA is better than other capacitance grades.

Comprehensive above analytical calculation situation, after 10kVS11 type Three-phase oil immersion type double winding non-excitation voltage regulation distribution transformer transformer is optimized, new capacitance grade sequence is 50kVA, 100kVA, 250kVA, 630kVA and 1600kVA.

As can be seen here, the former capacitance grade of 10kVS11 type Three-phase oil immersion type double winding non-excitation voltage regulation distribution transformer transformer standard code is 17, after adopting this optimization method to be optimized, be 5 capacitance grades, formed new more scientific and reasonable capacitance grade sequence.

According to specific exemplary embodiment, invention has been described herein.It will be apparent under not departing from the scope of the present invention, carrying out to one skilled in the art suitable replacement or revise.Exemplary embodiment is only illustrative, rather than the restriction to scope of the present invention, and scope of the present invention is defined by appended claim.

Claims (2)

1. a distribution transformer capacity sequence grade optimizing method, is characterized in that:

Under each Rate of average load of same load, close capacitance grade sequence is optimized, according to following formula, be optimized calculating:

${\mathrm{\&beta;}}_{\mathrm{ik}}=\frac{S_n}{S_i}\&times;{\mathrm{\&beta;}}_{\mathrm{nk}},$ K=1 wherein, 2,3 (1)

$\stackrel{\&OverBar;}{P_{\mathrm{ik}}}=\mathrm{AVERAGE}[P_{0i}+K_t{{\mathrm{\&beta;}}_{\mathrm{ik}}}^2{P}_{\mathrm{ki}}+C(Q_{0i}+K_t{{\mathrm{\&beta;}}_{\mathrm{ik}}}^2{Q}_{\mathrm{ki}})]---\left(2\right)$

In formula (1) and (2):

AVERAGE-mean value calculation;

K-load factor series number;

S _nselected reference capacity in-grouping;

S _ii in-grouping is waited level capacity;

β _ik-distribution transformer capacity is S _itime relative datum capacity S _nconversion load factor under each load factor;

β _nk-distribution transformer capacity is reference capacity S _ntime load factor;

load factor β in the combination of-distribution transformer capacity sequence _nkunder the average composite loss of transformer;

P _0i-distribution transformer capacity is S _ispecified unloaded active loss, unit is: kW;

Q _0i-distribution transformer capacity is S _ispecified unloaded reactive loss;

K _t-fluctuation of load loss factor, generally gets 1.05;

P _ki-distribution transformer capacity is S _inominal load active loss, unit is: kW;

Q _ki-distribution transformer capacity is S _ispecified unloaded reactive loss, unit is: kvar;

C-idle Economic Equivalent, unit is: kW/kvar; Idle Economic Equivalent gets 0.1 herein;

Distribution transformer for certain model carries out capacitance grade sequence optimisation, first should from minimum capacity grade, start grouping according to the rated capacity of relevant existing standard defined and calculate:

Grouping is exactly from the minimum capacity grade in the rated capacity sequence of described existing standard defined, 4～6 is one group, if found in calculating, until flex point does not appear in the average composite loss curve of heap(ed) capacity grade in grouping yet, can continue to increase the capacitance grade number in grouping; Circular can decompose (2) formula:

${\mathrm{\&beta;}}_i=\frac{S_n}{S_i}\&times;{\mathrm{\&beta;}}_n$

Wherein:

S _nfor the reference capacity capacity in grouping, the load factor of establishing reference capacity is β _n;

S _ifor i level capacity such as grade in grouping, β _ifor the conversion load factor of same load conversion to this capacitance grade;

P _i1＝P _0i+K _tβ _i1 ²P _ki+C(Q _0i+K _tβ _i1 ²Q _ki)

P _i2＝P _0i+K _tβ _i2 ²P _ki+C(Q _0i+K _tβ _i2 ²Q _ki)

：

：

：

$\stackrel{\&OverBar;}{P_i}=\mathrm{AVERAGE}\left(P_{\mathrm{ik}}\right),$ K=1 wherein, 2,3

Average composite loss according to each group capacity grade under its conversion load factor, makes the average composite loss curve of each group capacity grade, and abscissa is capacitance grade, the kVA of unit; Ordinate is average composite loss, and unit is kW; If there is obvious flex point in average composite loss curve, the capacitance grade that flex point occurs is the optimum capacity grade of the average composite loss minimum of this group capacity rate sequence, next capacitance grade of flex point of take is again starting point, proceed capacitance grade sequence of packets, according to above-mentioned steps, optimize successively calculating, until there is flex point, select the optimum capacity grade of this packeting average composite loss minimum; Then according to above grouping and optimized calculation method, until calculate the rated capacity of maximum existing standard defined, the new capacitance grade sequence after the flex point capacitance grade compositional optimization retaining in each group.

2. the method for claim 1, is characterized in that the method for claim 1 to be refined as following steps:

(1) the rated capacity grade of described existing standard defined is divided into groups from low to high, take 4～6 capacitance grades as one group, first determine first group, take lowest capacity grade as reference capacity grade, can calculate the payload under its different loads rate, wherein S according to (3) formula _nfor selected reference capacity in grouping; β _nkfor distribution transformer capacity is reference capacity S _ntime load factor, k=1,2,3 S _sjnkfor the actual load size under reference capacity grade different loads rate:

S _sjnk＝β _nkS _n （3）

(2) according to (4) formula, calculate composite loss and the mean value thereof under different loads rate under reference capacity:

$\stackrel{\&OverBar;}{P_{\mathrm{nk}}}=\mathrm{AVERAGE}[P_{0n}+K_t{{\mathrm{\&beta;}}_{\mathrm{nk}}}^2{P}_{\mathrm{kn}}+C(Q_{0n}+K_t{{\mathrm{\&beta;}}_{\mathrm{nk}}}^2{Q}_{\mathrm{kn}})]---\left(4\right)$

Wherein:

reference capacity grade load factor β in the combination of-distribution transformer capacity sequence _nkunder average composite loss;

P _0n-distribution transformer reference capacity S _nspecified unloaded active loss, unit is: kW;

Q _0n-distribution transformer reference capacity S _nspecified unloaded reactive loss;

K _t-fluctuation of load loss factor, generally gets 1.05;

P _kn-distribution transformer reference capacity S _nnominal load active loss, unit is: kW;

Q _kn-distribution transformer reference capacity S _nspecified unloaded reactive loss, unit is: kvar;

C-idle Economic Equivalent, unit is: kW/kvar; Idle Economic Equivalent gets 0.1 herein;

(3) calculate in grouping than the conversion load factor of the high capacitance grade of reference capacity grade, establishing in grouping is S than the capacity of the high grade of reference capacity grade _n+1, the conversion load factor β of this capacitance grade relative datum capacitance grade _{(n+1) k}can calculate according to (5) formula:

${\mathrm{\&beta;}}_{(n+1)k}=\frac{S_{\mathrm{sjnk}}}{S_{n+1}}---\left(5\right)$

(4) according to (6) formula calculate in grouping than composite loss and mean value thereof under the high capacitance grade conversion load factor of reference capacity grade:

$\stackrel{\&OverBar;}{P_{(n+1)k}}=\mathrm{AVERAGE}[P_{0(n+1)}+K_t{{\mathrm{\&beta;}}_{(n+1)k}}^2{P}_{k(n+1)}+C(Q_{0(n+1)}+K_t{{\mathrm{\&beta;}}_{(n+1)k}}^2{Q}_{k(n+1)})]---\left(6\right)$

Wherein:

in the combination of-distribution transformer capacity sequence, than the high capacitance grade of reference capacity, convert load factor β _{(n+1) k}under composite loss mean value;

P _{0 (n+1)}-than the high first-class level capacity S of distribution transformer reference capacity _n+1specified unloaded active loss, unit is: kW;

Q _{0 (n+1)}-than the high first-class level capacity S of distribution transformer reference capacity _n+1specified unloaded reactive loss;

P _{k (n+1)}-than the high first-class level capacity S of distribution transformer reference capacity _n+1nominal load active loss, unit is: kW;

Q _{k (n+1)}-than the high first-class level capacity S of distribution transformer reference capacity _n+1specified unloaded reactive loss, unit is: kvar;

(5) calculate in grouping than the reference capacity grade conversion load factor of a high capacitance grade again, establish in grouping than reference capacity grade again the capacity of a high grade be S _n+2, the conversion load factor β of this capacitance grade relative datum capacitance grade _{(n+2) k}can calculate according to (7) formula:

${\mathrm{\&beta;}}_{(n+2)k}=\frac{S_{\mathrm{sjnk}}}{S_{n+2}}---\left(7\right)$

(6) according to (8) formula calculate in grouping than reference capacity grade composite loss and the mean value thereof under a high capacitance grade conversion load factor again:

$\stackrel{\&OverBar;}{P_{(n+2)k}}=\mathrm{AVERAGE}[P_{0(n+2)}+K_t{{\mathrm{\&beta;}}_{(n+2)k}}^2{P}_{k(n+2)}+C(Q_{0(n+2)}+K_t{{\mathrm{\&beta;}}_{(n+2)k}}^2{Q}_{k(n+2)})]---\left(8\right)$

Wherein:

in-distribution transformer capacity sequence combination than a reference capacity high capacitance grade conversion load factor β again _{(n+2) k}under composite loss mean value;

P _{0 (n+2)}-than distribution transformer reference capacity high first-class level capacity S again _n+2specified unloaded active loss, unit is: kW;

Q _{0 (n+2)}-than distribution transformer reference capacity high first-class level capacity S again _n+2specified unloaded reactive loss;

P _{k (n+2)}-than distribution transformer reference capacity high first-class level capacity S again _n+2nominal load active loss, unit is: kW;

Q _{k (n+2)}-than the high first-class level capacity S of distribution transformer reference capacity _n+2specified unloaded reactive loss, unit is: kvar;

(7) calculate until flex point appears in the composite loss mean value in this grouping successively the optimizing capacity grade that capacitance grade corresponding to selected flex point place is this grouping;

(8) take the next capacitance grade of flex point as new reference capacity, again divide into groups from low to high, first calculate the payload under reference capacity grade different loads rate;

(9) repeating step (2)～(8), enter again next circulation, until the rated capacity rating calculation of maximum described existing standard defined is complete, if last pool-size grade does not have flex point to occur, the optimum capacity grade that the rated capacity grade of determining maximum described existing standard defined is this group;

(10) calculate each capacitance grade that divides into groups to retain and formed new capacitance grade sequence, be optimizing capacity rate sequence.

Images