CN105406472A - Safety working range based (N-1) calibration method for main transformer of medium-voltage power distribution system - Google Patents

Abstract

A safety working range based (N-1) calibration method for a main transformer of a medium-voltage power distribution system comprises the following steps of inputting structural information of the medium-voltage power distribution system for carrying out topological structure analysis on the medium-voltage power distribution system and carding a connection relation among circuits; carrying out wiring mode analysis on the medium-voltage power distribution system; reading information of a working point of the medium-voltage power distribution system; giving out a safety boundary of a safety working range of the main transformer of the medium-voltage power distribution system; calculating safety distance from the working point of the medium-voltage power distribution system to the safety boundary of the safety working range of the main transformer; judging a running state of the working point of the medium-voltage power distribution system; and giving out a (N-1) calibration result of the main transformer in a research region. According to the calibration method, the working point of the conventional power distribution system can be described from the perspective of a grid structure of the power distribution system and based on a feeder interconnection relation, the boundary of the safety working range of the main transformer of the medium-voltage power distribution system is further described, and the safety distance from the working point of the system to the boundary of the safety working range of the main transformer is calculated. By the calibration method, more comprehensive safety information can be provided, and the calibration method is more suitably used in real-time dispatching operation.

Description

Based on the intermediate distribution system main transformer N-1 method of calibration in trouble free service interval

Technical field

The present invention relates to a kind of power distribution network power supply safety method of calibration.Particularly relate to a kind of intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval.

Background technology

Distribution system as the important step of electrical energy production, transmission and use, be contact user with send out, the tie of transmission system.In distribution system planning, operation and when dispatching, N-1 safety criterion usually to be adopted to carry out the assessment of distribution system Connection Mode, namely check distribution system planning and designing or traffic control scheme whether to meet N-1 safety criterion.N-1 safety criterion requires power distribution network operationally, when certain independent component (as main transformer, feeder line etc.) in power distribution network breaks down, there will not be not right user to have a power failure in electrical network.Distribution system N-1 verification is the important means analyzing distribution system safety in operation and reliability, is also important component part very important in Electric Power Network Planning process, is of great significance Electric Power Network Planning and the equal tool of operation.

But, distribution system topological structure is changeable, element is in large scale, conventional electrical distribution system main transformer N-1 method of calibration is by carrying out N-1 verification one by one to the main transformer in survey region, namely under given point, suppose that each main transformer all likely breaks down, and analyze each main transformer break down after situation, by a large amount of simulation calculation verify this main transformer break down after electrical network whether safety, amount of calculation is large, computational speed is slow, and simulation result can only provide safe or unsafe judgement and which main transformer N-1 verification is not passed through, be difficult to provide the overall evaluation to the running status of system, if system operating point is how many apart from the nargin of dangerous running status, the capacity that working point exceeds safety value is how many, the direction of preventive control is carried out how to operating point, measure and be how many.

For solving the problem, building the describing method on the interval border of intermediate distribution system main transformer trouble free service and the computational methods of the interval frontier distance of system operating point distance main transformer trouble free service, there is good using value and construction value.

Summary of the invention

Technical problem to be solved by this invention is, a kind of intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval is provided, can from the angle of distribution system grid structure, based on feeder interconnection relationship, existing distribution system working point is described, and then describe the interval border of intermediate distribution system main transformer trouble free service, and computing system working point is to the safe distance on the interval border of main transformer trouble free service.

The technical solution adopted in the present invention is: a kind of intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval, comprises the steps:

1) intermediate distribution system structural information is inputted, for carrying out Analysis of Topological Structure to intermediate distribution system, the communication relationship between combing circuit;

2) Connection Mode analysis is carried out to intermediate distribution system, be be grouped into according to the circuit of different Connection Modes by intermediate distribution system: single radiation wiring, the wiring of simply connected network, wiring is got in touch with in segmentation two and segmentation three is got in touch with in the pattern of wiring, according to the feature of different Connection Mode, reading in of feeder line section quantity and load information carried out to circuit;

3) intermediate distribution system working point information is read in;

4) secure border in intermediate distribution system main transformer trouble free service interval is provided:

${\mathrm{\Ω}}_{DSTSI}=\left\{\begin{array}{c}{B}_{T1}:\underset{n\∈T_{j_{1|1}}}{\underset{m\∈T_1}{\Σ}}{\mathrm{trf}}_{mn}+P_{j_{1|1}}\≤{\mathrm{RT}}_{j_{1|1}}\\ B_{T2}:\underset{n\∈T_{j_{1|2}}}{\underset{m\∈T_1}{\Σ}}{\mathrm{trf}}_{mn}+P_{j_{1|2}}\≤{\mathrm{RT}}_{j_{1|2}}\\ .\\ .\\ .\\ B_{Tz}:\underset{n\∈T_{j_{x|y}}}{\underset{m\∈T_x}{\Σ}}{\mathrm{trf}}_{mn}+P_{j_{x|y}}\≤{\mathrm{RT}}_{j_{x|y}}\\ .\\ .\\ .\\ B_{Tk}:\underset{n\∈T_{j_{b|b\Σ}}}{\underset{m\∈T_b}{\Σ}}{\mathrm{trf}}_{mn}+P_{j_{b|b\Σ}}\≤{\mathrm{RT}}_{j_{b|b\Σ}}\end{array}\right.---\left(3\right)$

In formula: Ω _dSTSIrepresent that main transformer trouble free service is interval, described main transformer trouble free service interval is communicated with, without empty convex set and surrounded by the secure border in main transformer trouble free service interval; B _trepresent the secure border in main transformer trouble free service interval, described secure border is unique linear, hyperplane of compacting and can not tiing a knot of existing; B _tzrepresent z the secure border in main transformer trouble free service interval; B _tkrepresent last secure border in main transformer trouble free service interval; j _x|ythere is the y platform main transformer in the main transformer of communication relationship in expression and main transformer x; M ∈ T _xrepresent that feeder line m comes from the corresponding bus of main transformer x; represent that feeder line n comes from main transformer j _x|ycorresponding bus; represent main transformer j _x|yinstitute's on-load; represent main transformer j _x|ycapacity; j _{b|b Σ}there is last main transformer in the main transformer of communication relationship in expression and main transformer b; M ∈ T _brepresent that feeder line m comes from the corresponding bus of main transformer b; represent that feeder line n comes from main transformer j _{b|b Σ}corresponding bus; represent main transformer j _{b|b Σ}institute's on-load; represent main transformer j _{b|b Σ}capacity;

5) safe distance of intermediate distribution system working point to the interval secure border of main transformer trouble free service is calculated;

Described calculating obtains safe distance according to theorem in Euclid space point to the range formula of hyperplane, and computing formula is as follows:

$D_{Tz}=\[{\mathrm{RT}}_{j_{x|y}}-\underset{n\∈T_{j_{x|y}}}{\underset{m\∈T_x}{\Σ}}{\mathrm{trf}}_{mn}-P_{j_{x|y}}\]/\sqrt{N_{{\mathrm{xj}}_{x|y}}+N_{j_{x|y}}}---\left(4\right)$

In formula: D _trepresent that intermediate distribution system working point is to the interval secure border B of main transformer trouble free service _tsafe distance, D _tzrepresent that intermediate distribution system working point is to interval z the secure border B of main transformer trouble free service _tzsafe distance; when representing that main transformer x breaks down, main transformer x turns and brings main transformer j _x|yfeeder line section quantity; represent main transformer j _x|ythe feeder line section total quantity that feeder is divided into; Work as D _tzfor on the occasion of time, working point is in secure border B _tzwithin; Work as D _tzduring for negative value, working point is in secure border B _tzoutside; Work as D _tzwhen=0, represent that working point is criticality safety under main transformer N-1 constraints;

6) judge the running status of intermediate distribution system working point, namely judge that can intermediate distribution system current operating state be verified by main transformer N-1;

7) survey region electrical network main transformer N-1 check results is provided.

Step 1) in structural information comprise component information, line length, each load position and load peak, circuit breaker and isolating switch position and power distribution network communication relationship.

Step 3) n-dimensional vector that is made up of feeder line section load of described working point represents, expression is as follows:

W _f＝(f ₁,f ₂,…,f _h,…,f _l) ^T(1)

In formula: W _frepresent the working point vector based on feeder line section load; f _hrepresent the load of h feeder line section; L represents the number of the whole network feeder line section.

Step 4) be that basis based on the interval model of following intermediate distribution system trouble free service is carried out:

${\mathrm{\Ω}}_{DSSI}=\left\{\begin{array}{cc}{F}_m=\underset{n\∈F_m}{\Σ}{\mathrm{trf}}_{mn}& \∀m\\ P_i=\underset{m\∈F_i}{\Σ}{F}_m& \∀i\\ {\mathrm{trf}}_{ij}=\underset{n\∈T_j}{\underset{m\∈T_i}{\Σ}}{\mathrm{trf}}_{mn}& \∀i,j\\ {\mathrm{trf}}_{mn}+F_n\≤{\mathrm{RF}}_n& \∀m,n\\ {\mathrm{trf}}_{ij}+P_j\≤{\mathrm{RT}}_j& \∀i,j\end{array}\right.---\left(2\right)$

In formula: Ω _dSSIrepresent that intermediate distribution system trouble free service is interval, described trouble free service interval is communicated with, without empty convex set; F _mrepresent feeder line m with feeder line outlet load, for single radiation and single interconnector, F _mequal feeder line section load f _m, for many interconnectors, F _mequal the load sum of each feeder line section be divided into by feeder line m; F _nrepresent feeder line n with feeder line outlet load; trf _mnrepresent that feeder line m turns the load bringing feeder line n when breaking down; N ∈ F _mrepresent that feeder line n and feeder line m exists communication relationship; P _irepresent main transformer i institute on-load; P _jrepresent main transformer j institute on-load; M ∈ T _irepresent that feeder line m comes from the corresponding bus of main transformer i; N ∈ T _jrepresent that feeder line n comes from the corresponding bus of main transformer j; trt _ijrepresent that main transformer i turns the load bringing main transformer j when breaking down; RF _nrepresent the capacity of feeder line n; RT _jrepresent the capacity of main transformer j.

Step 6) in when intermediate distribution system working point is apart from all secure border B _tsafe distance D _tbe all on the occasion of time, described working point is within trouble free service interval, and namely working point meets all main transformer N-1 and retrains, and is in safe operation state; When intermediate distribution system working point is apart from all secure border B _tsafe distance D _tin arbitrary safe distance when being negative value, described working point is in outside trouble free service interval, has both been in dangerous running status, and wherein said negative value represents that main transformer load exceeds the load of corresponding secure border; When intermediate distribution system working point is apart from all secure border B _tsafe distance D _tin arbitrary safe distance when being 0, represent that working point is in criticality safety running status under main transformer N-1 constraints;

Each safe distance D _trepresent working point distance secure border B _tmargin of safety, D _tabsolute value larger expression working point distance secure border B _tfar away.

Intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval of the present invention, relative conventional electrical distribution system main transformer N-1 method of calibration, can from the angle of distribution system grid structure, based on feeder interconnection relationship, existing distribution system working point is described, and then describe the interval border of intermediate distribution system main transformer trouble free service, and computing system working point is to the safe distance on the interval border of main transformer trouble free service.Amount of calculation of the present invention reduces greatly, computational speed improves greatly, and can provide more fully security information, is more suitable for application in Real-Time Scheduling is run, be conducive to promoting Study on Power Grid Planning and traffic control level, promote the Rational Development of mains supply safety check technology.

Accompanying drawing explanation

Fig. 1 is the overall flow figure of the intermediate distribution system main transformer N-1 method of calibration that the present invention is based on trouble free service interval;

Fig. 2 is embodiment of the present invention network contact reduced graph used.

Embodiment

Below in conjunction with embodiment and accompanying drawing, the intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval of the present invention is described in detail.

Under the prerequisite that topological structure of electric is determined, power distribution system secure operation interval is well-determined, therefore for the electrical network that topological structure is certain, only need the interval border of calculated in advance main transformer trouble free service, then under any working point, only need calculate the distance on the interval border of the relatively each trouble free service in this working point, by the position of working point in trouble free service interval, namely the fail safe of working point can be judged, thus realize carrying out entirety verification to the whole network main transformer is disposable, and the capacity (when working point is dangerous) that the margin of safety (when working point is safe) on the interval border of distance trouble free service, working point or working point exceed safety value can be represented intuitively, the overall evaluation is provided to the running status of system.

Intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval of the present invention, on the basis of the power distribution system secure operation interval model based on feeder interconnection relationship, the describing method of the interval border (secure border) of structure intermediate distribution system main transformer trouble free service and system works point, to the computational methods of the interval frontier distance (safe distance) of main transformer trouble free service, are applicable to China's power distribution network power supply safety verifying work.

The power supply safety of urban distribution network adopts N-1 criterion, that is:

(1) lose in transformer station any one back into line or a step-down transformer time, do not lose load;

(2) overhead wire in high voltage distribution network, an or cable, or step-down transformer breaks down when stopping transport;

A. under normal circumstances, load is not lost;

B. to break down again under the condition of planned outage stoppage in transit, allow brownout, but should restore electricity in official hour;

(3) overhead wire in middle voltage distribution networks, an or cable, or in switchgear house a station power distribution transformer break down stop transport time;

A. under normal circumstances, do not have a power failure except faulty section, and brownout must not occur, and the unallowed overload of power supply unit;

B., in planned outage situation, there occurs again fault and stop transport, allow brownout, but should restore electricity at the appointed time.

(4) in low-voltage network, when a transformer or low-voltage circuit break down, allow brownout, restore electricity after pending fault reparation.

A platform main transformer: T is total in setting power supply area ₁, T ₂..., T _i..., T _a, b bar circuit: F ₁, F ₂..., F _m..., F _b.

As shown in Figure 1, the intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval of the present invention, comprises the steps:

1) intermediate distribution system structural information is inputted, for carrying out Analysis of Topological Structure to intermediate distribution system, communication relationship between combing circuit, middle comprises component information, line length, each load position and load peak, circuit breaker and isolating switch position and power distribution network communication relationship;

2) Connection Mode analysis is carried out to intermediate distribution system, be be grouped into according to the circuit of different Connection Modes by intermediate distribution system: single radiation wiring, the wiring of simply connected network, wiring is got in touch with in segmentation two and segmentation three is got in touch with in the pattern of wiring, according to the feature of different Connection Mode, reading in of feeder line section quantity and load information carried out to circuit;

3) read in intermediate distribution system working point information, the n-dimensional vector that described working point is made up of feeder line section load represents, expression is as follows:

W _f＝(f ₁,f ₂,…,f _m,…,f _n) ^T(1)

In formula: W _frepresent the working point vector based on feeder line section load; f _mrepresent the load of m feeder line section; N represents the number of the whole network feeder line section;

4) providing the interval border of intermediate distribution system main transformer trouble free service, is that the basis based on the interval model of following intermediate distribution system trouble free service is carried out:

${\mathrm{\Ω}}_{DSSI}=\left\{\begin{array}{cc}{F}_m=\underset{n\∈F_m}{\Σ}{\mathrm{trf}}_{mn}& \∀m\\ P_i=\underset{m\∈F_i}{\Σ}{F}_m& \∀i\\ {\mathrm{trf}}_{ij}=\underset{n\∈T_j}{\underset{m\∈T_i}{\Σ}}{\mathrm{trf}}_{mn}& \∀i,j\\ {\mathrm{trf}}_{mn}+F_n\≤{\mathrm{RF}}_n& \∀m,n\\ {\mathrm{trf}}_{ij}+P_j\≤{\mathrm{RT}}_j& \∀i,j\end{array}\right.---\left(2\right)$

In formula: Ω _dSSIrepresent that intermediate distribution system trouble free service is interval, described trouble free service interval is communicated with, without empty convex set; F _mrepresent feeder line m with feeder line outlet load, for single radiation and single interconnector, F _mequal feeder line section load f _m, for many interconnectors, F _mequal the load sum of each feeder line section be divided into by feeder line m; F _nrepresent feeder line n with feeder line outlet load; trf _mnrepresent that feeder line m turns the load bringing feeder line n when breaking down; N ∈ F _mrepresent that feeder line n and feeder line m exists communication relationship; P _irepresent main transformer i institute on-load; P _jrepresent main transformer j institute on-load; M ∈ T _irepresent that feeder line m comes from the corresponding bus of main transformer i; N ∈ T _jrepresent that feeder line n comes from the corresponding bus of main transformer j; trt _ijrepresent that main transformer i turns the load bringing main transformer j when breaking down; RF _nrepresent the capacity of feeder line n; RT _jrepresent the capacity of main transformer j;

The interval border of described intermediate distribution system main transformer trouble free service is as follows:

${\mathrm{\Ω}}_{DSTSI}=\left\{\begin{array}{c}{B}_{T1}:\underset{n\∈T_{j_{1|1}}}{\underset{m\∈T_1}{\Σ}}{\mathrm{trf}}_{mn}+P_{j_{1|1}}\≤{\mathrm{RT}}_{j_{1|1}}\\ B_{T2}:\underset{n\∈T_{j_{1|2}}}{\underset{m\∈T_1}{\Σ}}{\mathrm{trf}}_{mn}+P_{j_{1|2}}\≤{\mathrm{RT}}_{j_{1|2}}\\ .\\ .\\ .\\ B_{Tz}:\underset{n\∈T_{j_{x|y}}}{\underset{m\∈T_x}{\Σ}}{\mathrm{trf}}_{mn}+P_{j_{x|y}}\≤{\mathrm{RT}}_{j_{x|y}}\\ .\\ .\\ .\\ B_{Tk}:\underset{n\∈T_{j_{b|b\Σ}}}{\underset{m\∈T_b}{\Σ}}{\mathrm{trf}}_{mn}+P_{j_{b|b\Σ}}\≤{\mathrm{RT}}_{j_{b|b\Σ}}\end{array}\right.---\left(3\right)$

In formula: Ω _dSTSIrepresent that main transformer trouble free service is interval, described main transformer trouble free service interval is communicated with, without empty convex set and surrounded by the secure border in main transformer trouble free service interval; B _trepresent the secure border in main transformer trouble free service interval, described secure border is unique linear, hyperplane of compacting and can not tiing a knot of existing; B _tzrepresent z the secure border in main transformer trouble free service interval; B _tkrepresent last secure border in main transformer trouble free service interval; j _x|ythere is the y platform main transformer in the main transformer of communication relationship in expression and main transformer x; M ∈ T _xrepresent that feeder line m comes from the corresponding bus of main transformer x; represent that feeder line n comes from main transformer j _x|ycorresponding bus; represent main transformer j _x|yinstitute's on-load; represent main transformer j _x|ycapacity; j _{b|b Σ}there is last main transformer in the main transformer of communication relationship in expression and main transformer b; M ∈ T _brepresent that feeder line m comes from the corresponding bus of main transformer b; represent that feeder line n comes from main transformer j _{b|b Σ}corresponding bus; represent main transformer j _{b|b Σ}institute's on-load; represent main transformer j _{b|b Σ}capacity;

5) safe distance of intermediate distribution system working point to the interval secure border of main transformer trouble free service is calculated;

The fail safe of power distribution network can by determining that the position of working point in trouble free service interval is evaluated.All there is a safe distance intermediate distribution system working point, because arbitrary secure border is all the hyperplane of theorem in Euclid space to main transformer trouble free service each border interval.Described calculating is that to obtain Calculation of Safety Distance formula according to theorem in Euclid space point to the range formula of hyperplane as follows:

$D_{Tz}=\[{\mathrm{RT}}_{j_{x|y}}-\underset{n\∈T_{j_{x|y}}}{\underset{m\∈T_x}{\Σ}}{\mathrm{trf}}_{mn}-P_{j_{x|y}}\]/\sqrt{N_{{\mathrm{xj}}_{x|y}}+N_{j_{x|y}}}---\left(4\right)$

In formula: in formula: D _trepresent that intermediate distribution system working point is to the interval secure border B of main transformer trouble free service _tsafe distance, D _tzrepresent that intermediate distribution system working point is to interval z the secure border B of main transformer trouble free service _tzsafe distance; when representing that main transformer x breaks down, main transformer x turns and brings main transformer j _x|yfeeder line section quantity; represent main transformer j _x|ythe feeder line section total quantity that feeder is divided into; Work as D _tzfor on the occasion of time, working point is in secure border B _tzwithin; Work as D _tzduring for negative value, working point is in secure border B _tzoutside; Work as D _tzwhen=0, represent that working point is criticality safety under main transformer N-1 constraints;

6) judge the running status of intermediate distribution system working point, namely judge that can intermediate distribution system current operating state be verified by main transformer N-1, wherein:

When intermediate distribution system working point is apart from all secure border B _tsafe distance D _tbe all on the occasion of time, described working point is within trouble free service interval, and namely working point meets all main transformer N-1 and retrains, and is in safe operation state; When intermediate distribution system working point is apart from all secure border B _tsafe distance D _tin arbitrary safe distance when being negative value, described working point is in outside trouble free service interval, has both been in dangerous running status, and wherein said negative value represents that feeder load exceeds the load of corresponding secure border; When intermediate distribution system working point is apart from all secure border B _tsafe distance D _tin arbitrary safe distance when being 0, represent that working point is in criticality safety running status under main transformer N-1 constraints;

Each safe distance D _trepresent working point distance secure border B _tmargin of safety, D _tabsolute value larger expression working point distance secure border B _tfar away.

7) survey region electrical network main transformer N-1 check results is provided.

Provide instantiation below:

Suppose certain power supply block A, B, C3 seat transformer station altogether, feeder 18 times, feeder line all adopts JKLHYJ model aerial insulated wire.The circuit communication relationship of this network and main transformer essential information are distinguished as shown in Figure 2 and Table 1:

Table 1 transformer station overview

Choose electrical network two kinds of typical operation in this example, respectively the inventive method and traditional main transformer N-1 method of calibration are contrasted, to verify practicality and the accuracy of the inventive method.

Electrical network is under the first running status, and network configuration and working point information and main transformer N-1 verify comparing result respectively as shown in table 2 and table 3:

Table 2 network configuration and working point information (running status 1)

Table 3 main transformer N-1 verifies comparing result (running status 1)

Electrical network is under the first running status, and network configuration and working point information and main transformer N-1 verify comparing result respectively as shown in table 4 and table 5:

Table 4 network configuration and working point information (running status 2)

Table 5 main transformer N-1 verifies comparing result (running status 2)

As can be seen from the comparing result of table 3 with table 5, the check results of the inventive method and traditional main transformer N-1 method of calibration is completely the same; And traditional main transformer N-1 method of calibration amount of calculation is large, computational speed is slow, and is difficult to provide the overall evaluation to the running status of system; By contrast, the inventive method amount of calculation is little, and computational speed is fast, and achieves and verify the disposable integral of the whole network main transformer, can provide more intuitively, more fully security information, can provide the overall evaluation to the running status of system.Practicality and the accuracy of the inventive method can be verified with this.

Claims (5)

1., based on the intermediate distribution system main transformer N-1 method of calibration in trouble free service interval, it is characterized in that, comprise the steps:

1) intermediate distribution system structural information is inputted, for carrying out Analysis of Topological Structure to intermediate distribution system, the communication relationship between combing circuit;

2) Connection Mode analysis is carried out to intermediate distribution system, be be grouped into according to the circuit of different Connection Modes by intermediate distribution system: single radiation wiring, the wiring of simply connected network, wiring is got in touch with in segmentation two and segmentation three is got in touch with in the pattern of wiring, according to the feature of different Connection Mode, reading in of feeder line section quantity and load information carried out to circuit;

3) intermediate distribution system working point information is read in;

4) secure border in intermediate distribution system main transformer trouble free service interval is provided:

${\mathrm{\Ω}}_{DSTSI}=\left\{\begin{array}{c}{B}_{T1}:\underset{n\∈T_{j_{1|1}}}{\underset{m\∈T_1}{\mathrm{\Σ}}}{\mathrm{trf}}_{mn}+P_{j_{1|1}}\≤{\mathrm{RT}}_{j_{1|1}}\\ B_{T2}:\underset{n\∈T_{j_{1|2}}}{\underset{m\∈T_1}{\mathrm{\Σ}}}{\mathrm{trf}}_{mn}+P_{j_{1|2}}\≤{\mathrm{RT}}_{j_{1|2}}\\ \begin{array}{c}.\\ .\\ .\end{array}\\ B_{Tz}:\underset{n\∈T_{j_{x|y}}}{\underset{m\∈T_x}{\mathrm{\Σ}}}{\mathrm{trf}}_{mn}+P_{j_{x|y}}\≤{\mathrm{RT}}_{j_{x|y}}\\ \begin{array}{c}.\\ .\\ .\end{array}\\ B_{Tk}:\underset{n\∈T_{j_{b|b\mathrm{\Σ}}}}{\underset{m\∈T_b}{\mathrm{\Σ}}}{\mathrm{trf}}_{mn}+P_{j_{b|b\mathrm{\Σ}}}\≤{\mathrm{RT}}_{j_{b|b\mathrm{\Σ}}}\end{array}\right.---\left(3\right)$

In formula: Ω _dSTSIrepresent that main transformer trouble free service is interval, described main transformer trouble free service interval is communicated with, without empty convex set and surrounded by the secure border in main transformer trouble free service interval; B _trepresent the secure border in main transformer trouble free service interval, described secure border is unique linear, hyperplane of compacting and can not tiing a knot of existing; B _tzrepresent z the secure border in main transformer trouble free service interval; B _tkrepresent last secure border in main transformer trouble free service interval; j _x|ythere is the y platform main transformer in the main transformer of communication relationship in expression and main transformer x; M ∈ T _xrepresent that feeder line m comes from the corresponding bus of main transformer x; represent that feeder line n comes from main transformer j _x|ycorresponding bus; represent main transformer j _x|yinstitute's on-load; represent main transformer j _x|ycapacity; j _{b|b Σ}there is last main transformer in the main transformer of communication relationship in expression and main transformer b; M ∈ T _brepresent that feeder line m comes from the corresponding bus of main transformer b; represent that feeder line n comes from main transformer j _{b|b Σ}corresponding bus; represent main transformer j _{b|b Σ}institute's on-load; represent main transformer j _{b|b Σ}capacity;

5) safe distance of intermediate distribution system working point to the interval secure border of main transformer trouble free service is calculated;

Described calculating obtains safe distance according to theorem in Euclid space point to the range formula of hyperplane, and computing formula is as follows:

$D_{Tz}=\[{\mathrm{RT}}_{j_{x|y}}-\underset{n\∈T_{j_{x|y}}}{\underset{m\∈T_x}{\mathrm{\Σ}}}{\mathrm{trf}}_{mn}-P_{j_{x|y}}\]/\sqrt{N_{{\mathrm{xj}}_{x|y}}+N_{j_{x|y}}}---\left(4\right)$

In formula: D _trepresent that intermediate distribution system working point is to the interval secure border B of main transformer trouble free service _tsafe distance, D _tzrepresent that intermediate distribution system working point is to interval z the secure border B of main transformer trouble free service _tzsafe distance; when representing that main transformer x breaks down, main transformer x turns and brings main transformer j _x|yfeeder line section quantity; represent main transformer j _x|ythe feeder line section total quantity that feeder is divided into; Work as D _tzfor on the occasion of time, working point is in secure border B _tzwithin; Work as D _tzduring for negative value, working point is in secure border B _tzoutside; Work as D _tzwhen=0, represent that working point is criticality safety under main transformer N-1 constraints;

6) judge the running status of intermediate distribution system working point, namely judge that can intermediate distribution system current operating state be verified by main transformer N-1;

7) survey region electrical network main transformer N-1 check results is provided.

2. the intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval according to claim 1, it is characterized in that, step 1) in structural information comprise component information, line length, each load position and load peak, circuit breaker and isolating switch position and power distribution network communication relationship.

3. the intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval according to claim 1, is characterized in that, step 3) n-dimensional vector that is made up of feeder line section load of described working point represents, expression is as follows:

W _f＝(f ₁,f ₂,…,f _h,…,f _l) ^T(1)

In formula: W _frepresent the working point vector based on feeder line section load; f _hrepresent the load of h feeder line section; L represents the number of the whole network feeder line section.

4. the intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval according to claim 1, is characterized in that, step 4) be that basis based on the interval model of following intermediate distribution system trouble free service is carried out:

${\mathrm{\Ω}}_{DSSI}=\left\{\begin{array}{cc}{F}_m=\underset{n\∈F_m}{\Σ}{\mathrm{trf}}_{mn}& \∀m\\ P_i=\underset{m\∈F_i}{\Σ}{F}_m& \∀i\\ {\mathrm{trt}}_{ij}=\underset{n\∈T_j}{\underset{m\∈T_i}{\mathrm{\Σ}}}{\mathrm{trf}}_{mn}& \∀i,j\\ {\mathrm{trf}}_{mn}+F_n\≤{\mathrm{RF}}_n& \∀m,n\\ {\mathrm{trt}}_{ij}+P_j\≤{\mathrm{RT}}_j& \∀i,j\end{array}\right.---\left(2\right)$

In formula: Ω _dSSIrepresent that intermediate distribution system trouble free service is interval, described trouble free service interval is communicated with, without empty convex set; F _mrepresent feeder line m with feeder line outlet load, for single radiation and single interconnector, F _mequal feeder line section load f _m, for many interconnectors, F _mequal the load sum of each feeder line section be divided into by feeder line m; F _nrepresent feeder line n with feeder line outlet load; trf _mnrepresent that feeder line m turns the load bringing feeder line n when breaking down; N ∈ F _mrepresent that feeder line n and feeder line m exists communication relationship; P _irepresent main transformer i institute on-load; P _jrepresent main transformer j institute on-load; M ∈ T _irepresent that feeder line m comes from the corresponding bus of main transformer i; N ∈ T _jrepresent that feeder line n comes from the corresponding bus of main transformer j; trt _ijrepresent that main transformer i turns the load bringing main transformer j when breaking down; RF _nrepresent the capacity of feeder line n; RT _jrepresent the capacity of main transformer j.

5. the intermediate distribution system main transformer N-1 method of calibration based on trouble free service interval according to claim 1, is characterized in that, step 6) in when intermediate distribution system working point is apart from all secure border B _tsafe distance D _tbe all on the occasion of time, described working point is within trouble free service interval, and namely working point meets all main transformer N-1 and retrains, and is in safe operation state; When intermediate distribution system working point is apart from all secure border B _tsafe distance D _tin arbitrary safe distance when being negative value, described working point is in outside trouble free service interval, has both been in dangerous running status, and wherein said negative value represents that main transformer load exceeds the load of corresponding secure border; When intermediate distribution system working point is apart from all secure border B _tsafe distance D _tin arbitrary safe distance when being 0, represent that working point is in criticality safety running status under main transformer N-1 constraints;

Each safe distance D _trepresent working point distance secure border B _tmargin of safety, D _tabsolute value larger expression working point distance secure border B _tfar away.