CN104485660A - Directed relational graph-based power distribution network reliability evaluation method - Google Patents

Abstract

The invention discloses a directed relational graph-based power distribution network reliability evaluation method. According to the method, a power distribution network is divided into protection zones (CZ) of different levels and feeder layers (FS) according to protection zones of circuit breakers in the power distribution network and segmental acting of disconnecting switches in feeders, so that a digraph of the power distribution network can be constructed; and the digraph can be conveniently applied to reliability evaluation of the power distribution network and can be directly applied to a power distribution network with a distributed power source; the greater an ASAI value is, the higher reliability is, and the smaller the SAIFI, SAIDI, CAIDI and AENS values are, the higher the reliability is, and therefore, the reliability of the power distribution network system can be evaluated. The directed relational graph-based power distribution network reliability evaluation method of the invention can be widely applied to the reliability evaluation of medium-voltage power distribution networks. With the directed relational graph-based power distribution network reliability evaluation adopted, defects of an existing failure mode and effect analysis method and blocking algorithm can be eliminated.

Description

A kind of distribution network reliability evaluation method based on oriented graph of a relation

Technical field

The present invention relates to power distribution network safe and reliable operation technical field, particularly relate to a kind of distribution network reliability evaluation method based on oriented graph of a relation.Both may be used for the reliability assessment of conventional electrical distribution net, also may be used for the reliability assessment of the power distribution network containing distributed power source.

Background technology

Power distribution network is the link directly in the face of user in electric power system, the most direct on the impact of customer power supply quality and power supply reliability, the reliability of power distribution network can be improved by carrying out reliability assessment to power distribution network, ensure power supply quality, promotion and improve power industry production technology, management, raising economic and social benefit etc. all tool be of great significance.

The reliability estimation method of traditional power distribution network extensively adopts fault mode consequences analysis method (FMEA).Fault mode consequences analysis method is the reliability data utilizing power distribution network element, sets up the fault mode consequence table that power distribution network runs, analyzes each event of failure and consequence thereof, then comprehensively form reliability index.But when the complex structure of power distribution network, the foundation of fault mode consequence table will be very difficult, so the reliability assessment directly utilizing fault mode consequences analysis method to carry out Complicated Distribution Network is very difficult.The network equivalent technology of Complex Distribution System Reliability Assessment in order to simplify the reliability assessment step of power distribution network, but when containing more sub-feeder line in power distribution network, will be difficult to the equivalent network obtaining Complicated Distribution Network.

The reliability estimation method of power distribution network also uses minimal path algorithm, minimal path algorithm is when carrying out reliability assessment, first ask the minimal path of each load point, consider that element on minimal path and non-minimum road is on the impact of the reliability of load point more respectively, element on non-minimum road is converted in minimal path on the impact of load point by certain criterion, then to calculate in minimal path element to the impact (comprising Equivalence effects) of load point reliability index, thus try to achieve reliability index.

Power distribution network has a large capacity and a wide range, and network breaker in middle number of devices numerous and its type, Various Functions, sub-feeder line form connects the features such as complicated, these factors all add the difficulty of evaluating reliability of distribution network, and therefore research improves the Main Scientific Issues that the speed of evaluating reliability of distribution network and precision are this fields current.Increasingly mature along with distributed generation technology, distributed power source (DG) is access in power distribution network more and more by means of advantages such as its generation mode flexibility, environment friendly, creates significant impact to the structure of distribution system and operation.Produce what impact to the reliability of power distribution network after distributed power source (DG) accesses power distribution network, this is the problem that user and Utilities Electric Co. are concerned about most actually.So, be the task of top priority to the reliability assessment of the power distribution network containing distributed power source.

Summary of the invention

The object of this invention is to provide a kind of distribution network reliability evaluation method based on oriented graph of a relation, can on the basis of original power distribution network network configuration, by the reliability of the reliability index of load point assessment distribution network system, not only may be used for conventional electrical distribution net but also the reliability assessment of the power distribution network containing distributed power source can have been applied to.

The technical solution used in the present invention is:

Based on a distribution network reliability evaluation method for oriented graph of a relation, it is characterized in that: comprise the following steps:

A: gather the structured data of power distribution network to be assessed, electric parameter data and reliability parameters data bank;

B: the data gathered according to steps A, carries out piecemeal and classification to power distribution network network configuration;

Based on the difference of different elements fault effects in power distribution network, power distribution network is carried out piecemeal and classification in accordance with the following steps:

B1: the direct first section of circuit breaker be connected with major network bus is divided into first order circuit breaker, and is designated as CB11;

B2: under system failure running status, be starting point based on Depth Priority Algorithm with CB11, start on the feeder line at CB11 place along direction of tide search element, the end searching a circuit breaker or search feeder line then stops the party's search upwards, the search on other directions is proceeded again, until all direction search terminate from CB11; The protection zone of all element composition CB11 then searched in this process forms a block, and is called first class of protection district, is designated as CZ11;

B3: the method utilizing step B1 and B2, specify that the circuit breaker of the downstream direction of tide be directly connected with CZ (i-1) (j-1) is called i-th grade of circuit breaker, and protection zone corresponding to i-th grade of circuit breaker is called jth level protection zone, search obtains other circuit breaker CBij and respective protection zone CZij thereof, wherein, if CBij represents the jth circuit breaker in i-th grade of protection zone; CZij represents the jth block in i-th grade of protection zone; Staged and block is divided by whole power distribution network;

C: according to the partition of the level of protection zone CZij, sets up the oriented graph of a relation of initial power distribution network, namely the oriented graph of a relation of power distribution network be by the protection zone of all levels according to the first order, the second level, the third level ..., i-th grade arrange formation from top to bottom;

D: segmentation is carried out to the feeder line in CZij; CZij is divided into different feeder line section FS by the position according to block switch, and partiting step is as follows:

D1: first set feeder lines all in CZij as the feeder line section of the first level, be designated as FSij1;

D2: direction of tide search block switch when normally running along power distribution network in CZij, when searching the 1st block switch, being revised as the feeder line section of the 2nd level, being designated as FSij2 by feeder lines all for this block switch downstream;

D3: according to the method for step D2, when searching kth-1 block switch, being revised as the feeder line section of kth level, being designated as FSijk by feeder lines all for this block switch downstream; Continue search block switch, block switches all in CZij is all searched and till segmentation;

E: obtained the feeder line section information in each protection zone by step D2 and D3, in the existing oriented graph of a relation of power distribution network set up by feeder line section information insertion step C in each protection zone, obtains the oriented graph of a relation of final power distribution network;

F: the dependability parameter equivalence of element in feeder line section;

Because the fault of element in same feeder line section is all identical on the impact of load point, so the element identical to load point reliability effect is divided into an equivalent feeder line, respectively with equivalent fault rate λ _ewith equivalence γ repair time _erepresent the reliability index of this feeder line section;

${\mathrm{\λ}}_e=\underset{i=1}{\overset{N_c}{\mathrm{\Σ}}}{\mathrm{\λ}}_i---\left(1\right)$

${\mathrm{\γ}}_e=\frac{\underset{i=1}{\overset{N_c}{\mathrm{\Σ}}}{\mathrm{\λ}}_i{\mathrm{\γ}}_i}{{\mathrm{\λ}}_e}---\left(2\right)$

In formula: N _cfor the number of element in this equivalent feeder line section, λ _iand γ _ibe respectively failure rate and the repair time of i-th element in this equivalent feeder line section;

G: the failure rate and the annual interruption duration that calculate distribution network load point according to the oriented graph of a relation of final power distribution network;

G1: when not containing distributed power source in system, the failure rate of load point and annual interruption duration, the i.e. calculating of the reliability index of load point;

Suppose, Mi is the number of the feeder line section in a jth piecemeal of i-th grade of protection zone CZij, and si is i-th grade of protection zone CZij and the i-th+1 grade protection zone CZi _{+ 1}connected node, N (k) is the protection zone number between load point k to power supply, then (3) and (4) the failure rate of load point k and annual interruption duration are calculated by formula:

$\mathrm{\λ}\left(k\right)=\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=i}{\overset{M_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}+{\mathrm{\λ}}_{\mathrm{mg}}---\left(3\right)$

$U\left(k\right)=\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=1}{\overset{s_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}{\mathrm{\γ}}_{\mathrm{ij}}+\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=s_{i+1}}{\overset{M_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}{t}_{\mathrm{ds}}+{\mathrm{\λ}}_{\mathrm{mg}}{\mathrm{\γ}}_{\mathrm{mg}}---\left(4\right)$

In formula, λ (k) and U (k) is respectively failure rate and the annual interruption duration of load point k; λ _ijand γ _ijit is failure rate and the repair time of a jth feeder line section FSij in i-th CZij; t _dsfor the isolated operation time of switch; λ _mgand γ _mgfor failure rate and the repair time of major network;

G2: when calculating containing distributed photovoltaic power, the failure rate of load point and average year interruption duration;

The history of distributed power source is utilized to go out force data to determine failure rate λ ' (k) and average year interruption duration U ' (k) of load point k, as (5), (6) formula is depicted as:

${\mathrm{\λ}}^{\′}\left(k\right)=\frac{1}{N_{\mathrm{pv}}}\underset{j=1}{\overset{N_{\mathrm{pv}}}{\mathrm{\Σ}}}\frac{\max \{P_{\mathrm{ak}}-P_j,0\}}{P_{\mathrm{ak}}}\mathrm{\λ}\left(k\right)---\left(5\right)$

$U^{\′}\left(k\right)=\frac{1}{N_{\mathrm{pv}}}\underset{j=1}{\overset{N_{\mathrm{pv}}}{\mathrm{\Σ}}}\frac{\max \{P_{\mathrm{ak}}-P_j,0\}}{P_{\mathrm{ak}}}U\left(k\right)---\left(6\right)$

In formula, P _j(j=1,2 ..., N _pV) the exerting oneself in jth hour that be distributed photovoltaic power; N _pVit is total hourage; P _akfor the power of load point k;

G3: calculate containing load point failure rate during distributed diesel generating set and average year interruption duration;

Because diesel generating set is only start when major network fault, the frequency of power cut that therefore access of diesel generating set can't reduce load point only can reduce the annual interruption duration of load point; Load point k failure rate λ " (k) and average year interruption duration U " (k) (7) (8) calculated with formula by formula:

(k)=λ ' (k) (7) for λ " (k)=λ (k) or λ "

U " (k)=p _udλ (k) t _di+ p _ddu (k) or U " (k)=p _udλ ' (k) t _di+ p _ddu ' (k)

⑻

In formula, t _difor the start-up time of diesel engine generator, P _udand P _ddbe respectively availability factor and the unavailability ratio of diesel generating set;

H: the reliability index calculating distribution network system, exports result of calculation;

Distribution network system reliability index is calculated by following formula:

$\mathrm{SAIFI}=\frac{{\mathrm{\Σ}}_{k\∈R}\mathrm{\λ}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIFI}=\frac{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIFI}=\frac{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}---\left(9\right)$

$\mathrm{SAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}U\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}---\left(10\right)$

$\mathrm{ASAI}=\frac{{\mathrm{\Σ}}_{k\∈R}8760C_k-{\mathrm{\Σ}}_{i\∈R}U\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}8760C_k}$ Or $\mathrm{ASAI}=\frac{{\mathrm{\Σ}}_{k\∈R}8760C_k-{\mathrm{\Σ}}_{i\∈R}{U}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}8760C_k}$

Or $\mathrm{ASAI}=\frac{{\mathrm{\Σ}}_{k\∈R}8760C_k-{\mathrm{\Σ}}_{i\∈R}{U}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}8760C_k}---\left(11\right)$

$\mathrm{CAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}U\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}\mathrm{\λ}\left(k\right)C_k}$ Or $\mathrm{CAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′}\left(k\right)C_k}$ Or $\mathrm{CAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′\′}\left(k\right)C_k}---\left(12\right)$

$\mathrm{AENS}=\frac{{\mathrm{\Σ}}_{k\∈R}{P}_{\mathrm{ak}}U\left(k\right)}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{AENS}=\frac{{\mathrm{\Σ}}_{k\∈R}{P}_{\mathrm{ak}}{U}^{\′}\left(k\right)}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{AENS}=\frac{{\mathrm{\Σ}}_{k\∈R}{P}_{\mathrm{ak}}{U}^{\′\′}\left(k\right)}{{\mathrm{\Σ}}_{k\∈R}{C}_k}---\left(13\right)$

In formula, λ (k) and U (k) is respectively failure rate and the annual interruption duration of load point k when not containing distributed power source, λ ' (k) and U ' (k) are respectively failure rate containing load point k during distributed photovoltaic power and annual interruption duration, λ " (k) and U " (k) is respectively failure rate containing load point k during distributed diesel generating set and annual interruption duration, is failure rate and the annual interruption duration of load point k corresponding in formula (3)-(10); C _kit is the number of users that a kth load point connects; P _akfor a kth load point power; R is load point set;

SAIFI refers to system System average interruption frequency, i.e. the average frequency of power cut that is subjected within the unit interval of each user, is represented with the ratio of number of users by user's total degree that has a power failure; SAIDI refers to system System average interruption duration, and namely the System average interruption duration that suffered in 1 year of user, is represented by the ratio of customer outage hours summation with number of users; CAIDI refers to user's System average interruption duration, i.e. each user each average duration had a power failure in 1 year, is represented by the have a power failure ratio of total degree of customer outage hours summation and user; ASAI refers on average power availability factor, i.e. each user percentage of time that need for electricity is met in a year, and time total by actual power, amount represents with the ratio of amount when requiring to power total; AENS refers to that system on average lacks amount of power supply, is namely represented by the ratio of total short of electricity amount with total number of users;

I: the result calculated according to step H, the value according to ASAI is larger, and reliability is higher; The value of SAIFI, SAIDI, CAIDI and AENS is less, and reliability is higher, thus the reliability of assessment distribution network system.

The present invention power distribution network is divided into the protection zone (CZ) of different levels according to isolating switch segmenting function in the protection zone of circuit breaker in power distribution network and feeder line and feeder line layer (FS) sets up power distribution network directed graph; this directed graph can be advantageously used in the reliability assessment of power distribution network, and is directly used in containing distributed power source power distribution network.The present invention is widely used in the middle of the reliability assessment of medium voltage distribution network, overcomes the deficiency of existing fault mode consequences analysis method and block algorithm etc.。

Accompanying drawing explanation

Fig. 1 is evaluating reliability of distribution network flow chart of the present invention;

Fig. 2 is a certain simple power distribution network network configuration of the present invention;

Fig. 3 is piecemeal and the classification figure of simple power distribution network network of the present invention;

Fig. 4 is the oriented graph of a relation of the simple power distribution network network containing CZ of the present invention;

Fig. 5 is the oriented graph of a relation of the simple power distribution network network containing CZ and FS of the present invention;

Fig. 6 is before the dependability parameter equivalence of element in feeder line layer of the present invention;

Fig. 7 is after the dependability parameter equivalence of element in feeder line layer of the present invention;

Fig. 8 is the oriented graph of a relation of power distribution network taking into account distributed power source of the present invention;

Fig. 9 is of the present invention and takes no account of the oriented graph of a relation of power distribution network of distributed power source;

Figure 10 is certain community power distribution network network structure of the present invention.

Embodiment

As shown in Figure 1, the present invention includes the distribution network reliability evaluation method based on oriented graph of a relation, it is characterized in that: comprise the following steps:

A: gather the structured data of power distribution network to be assessed, electric parameter data and reliability parameters data bank;

B: the data gathered according to steps A, carries out piecemeal and classification to power distribution network network configuration;

Based on the difference of different elements fault effects in power distribution network, power distribution network is carried out piecemeal and classification in accordance with the following steps:

B1: the direct first section of circuit breaker be connected with major network bus is divided into first order circuit breaker, and is designated as CB11;

B2: under system failure running status, be starting point based on Depth Priority Algorithm with CB11, start on the feeder line at CB11 place along direction of tide search element, the end searching a circuit breaker or search feeder line then stops the party's search upwards, the search on other directions is proceeded again, until all direction search terminate from CB11; The protection zone of all element composition CB11 then searched in this process forms a block, and is called first class of protection district, is designated as CZ11;

B3: the method utilizing step B1 and B2, specify that the circuit breaker of the downstream direction of tide be directly connected with CZ (i-1) (j-1) is called i-th grade of circuit breaker, and protection zone corresponding to i-th grade of circuit breaker is called jth level protection zone, search obtains other circuit breaker CBij and respective protection zone CZij thereof, wherein, if CBij represents the jth circuit breaker in i-th grade of protection zone; CZij represents the jth block in i-th grade of protection zone; Staged and block is divided by whole power distribution network;

C: according to the partition of the level of protection zone CZij, sets up the oriented graph of a relation of initial power distribution network, namely the oriented graph of a relation of power distribution network be by the protection zone of all levels according to the first order, the second level, the third level ..., i-th grade arrange formation from top to bottom;

D: segmentation is carried out to the feeder line in CZij; CZij is divided into different feeder line section FS by the position according to block switch, and partiting step is as follows:

D1: first set feeder lines all in CZij as the feeder line section of the first level, be designated as FSij1;

D2: direction of tide search block switch when normally running along power distribution network in CZij, when searching the 1st block switch, being revised as the feeder line section of the 2nd level, being designated as FSij2 by feeder lines all for this block switch downstream;

D3: according to the method for step D2, when searching kth-1 block switch, being revised as the feeder line section of kth level, being designated as FSijk by feeder lines all for this block switch downstream; Continue search block switch, block switches all in CZij is all searched and till segmentation;

E: obtained the feeder line section information in each protection zone by step D2 and D3, in the existing oriented graph of a relation of power distribution network set up by feeder line section information insertion step C in each protection zone, obtains the oriented graph of a relation of final power distribution network;

F: the dependability parameter equivalence of element in feeder line section;

Because the fault of element in same feeder line section is all identical on the impact of load point, so the element identical to load point reliability effect is divided into an equivalent feeder line, respectively with equivalent fault rate λ _ewith equivalence γ repair time _erepresent the reliability index of this feeder line section;

${\mathrm{\λ}}_e=\underset{i=1}{\overset{N_c}{\mathrm{\Σ}}}{\mathrm{\λ}}_i---\left(1\right)$

${\mathrm{\γ}}_e=\frac{\underset{i=1}{\overset{N_c}{\mathrm{\Σ}}}{\mathrm{\λ}}_i{\mathrm{\γ}}_i}{{\mathrm{\λ}}_e}---\left(2\right)$

In formula: N _cfor the number of element in this equivalent feeder line section, λ _iand γ _ibe respectively failure rate and the repair time of i-th element in this equivalent feeder line section;

G: the failure rate and the annual interruption duration that calculate distribution network load point according to the oriented graph of a relation of final power distribution network;

G1: when not containing distributed power source in system, the failure rate of load point and annual interruption duration, the i.e. calculating of the reliability index of load point;

Suppose, Mi is the number of the feeder line section in a jth piecemeal of i-th grade of protection zone CZij, and si is i-th grade of protection zone CZij and the i-th+1 grade protection zone CZi _{+ 1}connected node, N (k) is the protection zone number between load point k to power supply, then (3) and (4) the failure rate of load point k and annual interruption duration are calculated by formula:

$\mathrm{\λ}\left(k\right)=\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=i}{\overset{M_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}+{\mathrm{\λ}}_{\mathrm{mg}}---\left(3\right)$

$U\left(k\right)=\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=1}{\overset{s_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}{\mathrm{\γ}}_{\mathrm{ij}}+\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=s_{i+1}}{\overset{M_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}{t}_{\mathrm{ds}}+{\mathrm{\λ}}_{\mathrm{mg}}{\mathrm{\γ}}_{\mathrm{mg}}---\left(4\right)$

In formula, λ (k) and U (k) is respectively failure rate and the annual interruption duration of load point k; λ _ijand γ _ijit is failure rate and the repair time of a jth feeder line section FSij in i-th CZij; t _dsfor the isolated operation time of switch; λ _mgand γ _mgfor failure rate and the repair time of major network;

G2: when calculating containing distributed photovoltaic power, the failure rate of load point and average year interruption duration;

The history of distributed power source is utilized to go out force data to determine failure rate λ ' (k) and average year interruption duration U ' (k) of load point k, as (5), (6) formula is depicted as:

${\mathrm{\λ}}^{\′}\left(k\right)=\frac{1}{N_{\mathrm{pv}}}\underset{j=1}{\overset{N_{\mathrm{pv}}}{\mathrm{\Σ}}}\frac{\max \{P_{\mathrm{ak}}-P_j,0\}}{P_{\mathrm{ak}}}\mathrm{\λ}\left(k\right)---\left(5\right)$

$U^{\′}\left(k\right)=\frac{1}{N_{\mathrm{pv}}}\underset{j=1}{\overset{N_{\mathrm{pv}}}{\mathrm{\Σ}}}\frac{\max \{P_{\mathrm{ak}}-P_j,0\}}{P_{\mathrm{ak}}}U\left(k\right)---\left(6\right)$

In formula, P _j(j=1,2 ..., N _pV) the exerting oneself in jth hour that be distributed photovoltaic power; N _pVit is total hourage; P _akfor the power of load point k;

G3: calculate containing load point failure rate during distributed diesel generating set and average year interruption duration;

Because diesel generating set is only start when major network fault, the frequency of power cut that therefore access of diesel generating set can't reduce load point only can reduce the annual interruption duration of load point; Load point k failure rate λ " (k) and average year interruption duration U " (k) (7) (8) calculated with formula by formula:

(k)=λ ' (k) (7) for λ " (k)=λ (k) or λ "

U " (k)=p _udλ (k) t _di+ p _ddu (k) or U " (k)=p _udλ ' (k) t _di+ p _ddu ' (k) (8)

In formula, t _difor the start-up time of diesel engine generator, p _udand p _ddbe respectively availability factor and the unavailability ratio of diesel generating set;

H: the reliability index calculating distribution network system, exports result of calculation;

Distribution network system reliability index is calculated by following formula:

$\mathrm{SAIFI}=\frac{{\mathrm{\Σ}}_{k\∈R}\mathrm{\λ}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIFI}=\frac{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIFI}=\frac{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}---\left(9\right)$ $\mathrm{SAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}U\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}---\left(10\right)$

$\mathrm{ASAI}=\frac{{\mathrm{\Σ}}_{k\∈R}8760C_k-{\mathrm{\Σ}}_{i\∈R}U\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}8760C_k}$ Or $\mathrm{ASAI}=\frac{{\mathrm{\Σ}}_{k\∈R}8760C_k-{\mathrm{\Σ}}_{i\∈R}{U}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}8760C_k}$

Or $\mathrm{ASAI}=\frac{{\mathrm{\Σ}}_{k\∈R}8760C_k-{\mathrm{\Σ}}_{i\∈R}{U}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}8760C_k}---\left(11\right)$

$\mathrm{CAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}U\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}\mathrm{\λ}\left(k\right)C_k}$ Or $\mathrm{CAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′}\left(k\right)C_k}$ Or $\mathrm{CAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′\′}\left(k\right)C_k}---\left(12\right)$

$\mathrm{AENS}=\frac{{\mathrm{\Σ}}_{k\∈R}{P}_{\mathrm{ak}}U\left(k\right)}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{AENS}=\frac{{\mathrm{\Σ}}_{k\∈R}{P}_{\mathrm{ak}}{U}^{\′}\left(k\right)}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{AENS}=\frac{{\mathrm{\Σ}}_{k\∈R}{P}_{\mathrm{ak}}{U}^{\′\′}\left(k\right)}{{\mathrm{\Σ}}_{k\∈R}{C}_k}---\left(13\right)$

In formula, λ (k) and U (k) is respectively failure rate and the annual interruption duration of load point k when not containing distributed power source, λ ' (k) and U ' (k) are respectively failure rate containing load point k during distributed photovoltaic power and annual interruption duration, λ " (k) and U " (k) is respectively failure rate containing load point k during distributed diesel generating set and annual interruption duration, is failure rate and the annual interruption duration of load point k corresponding in formula (3)-(10); C _kit is the number of users that a kth load point connects; P _akfor a kth load point power; R is load point set;

SAIFI refers to system System average interruption frequency, i.e. the average frequency of power cut that is subjected within the unit interval of each user, is represented with the ratio of number of users by user's total degree that has a power failure; SAIDI refers to system System average interruption duration, and namely the System average interruption duration that suffered in 1 year of user, is represented by the ratio of customer outage hours summation with number of users; CAIDI refers to user's System average interruption duration, i.e. each user each average duration had a power failure in 1 year, is represented by the have a power failure ratio of total degree of customer outage hours summation and user; ASAI refers on average power availability factor, i.e. each user percentage of time that need for electricity is met in a year, and time total by actual power, amount represents with the ratio of amount when requiring to power total; AENS refers to that system on average lacks amount of power supply, is namely represented by the ratio of total short of electricity amount with total number of users;

I: the result calculated according to step H, the value according to ASAI is larger, and reliability is higher; The value of SAIFI, SAIDI, CAIDI and AENS is less, and reliability is higher, thus the reliability of assessment distribution network system.

Detailed process of the present invention is described in detail below in conjunction with accompanying drawing:

As shown in Figure 1, be evaluating reliability of distribution network flow chart of the present invention.For ease of thinking of the present invention is described, be described below with a certain simple power distribution network network to institute of the present invention extracting method, as shown in Figure 2, as can see from Figure 2, by major network branch out multichannel branch, in figure, LP is load point to this simple network.

Step 1: gather power distribution network master data information

Gather the information such as distribution net work structure data to be assessed, electric parameter data, reliability parameters data bank, these data are used for the Calculation of Reliability analysis in later stage.

Step 2: piecemeal and classification are carried out to power distribution network network configuration

According to the direction of trend, with certain equipment for the element in feeder line can be divided into upstream element and downstream components by benchmark, all elements being namely positioned at this equipment front by direction of tide are called the upstream element of this equipment, on the contrary, are called the downstream components of this element.Definition according to upstream and downstream element is known, the fault of circuit breaker downstream components can not affect the element of upstream, but circuit breaker upstream element fault can cause its all downstream components to stop transport.Based on the difference of different elements fault effects in power distribution network, power distribution network is carried out piecemeal and classification in accordance with the following steps:

The direct first section of circuit breaker be connected with major network bus is divided into first order circuit breaker by step 2.1, and is designated as CB11; Composition graphs 3 can be seen, what be directly connected with major network is CB11 circuit breaker.

Step 2.2 searches for the protection zone of circuit breaker CB11;

Under system failure running status, be that starting point starts on the feeder line at CB11 place along direction of tide search element with CB11 based on Depth Priority Algorithm, search the search that circuit breaker or feeder line branch road end then stop this direction, again along other directions search element, until all direction search terminate.The combination of all elements then searched in this process forms a block, and this block is the protection zone of CB11, and is called for first class of protection district, is designated as CZ11.Composition graphs 3 can be found out; element is searched on the feeder line at CB11 place; circuit breaker CB21 and normally closed switch can be searched; but normally closed switch is not the condition stopping search; so, continue to search for downwards, circuit breaker CB22, CB23 can be searched; now stop search, then the CZ11 shown in Fig. 3 is the protection zone of circuit breaker CB11.

Step 2.3 determines second level circuit breaker and protection zone thereof

The circuit breaker of downstream direction of tide that regulation and CZ11 are directly connected is called second level circuit breaker, and protection zone corresponding to second level circuit breaker is called protection zone, the second level.As shown in Figure 3, CB21, CB22 and CB23 are second level circuit breaker.Obtain CB21, CB22 and CB23 protection zone CZ21, CZ22 and CZ23 separately by the searching method of stating in rapid 2.2, claim them to be protection zone, the second level.

Step 2.4 by that analogy, specify that the circuit breaker of the downstream direction of tide be directly connected with CZ (i-1) (j-1) is called i-th grade of circuit breaker, and protection zone corresponding to i-th grade of circuit breaker is called jth level protection zone, search obtains other circuit breaker CBij and respective protection zone CZij thereof, wherein, if CBij represents the jth circuit breaker in i-th grade of protection zone; CZij represents the jth block in i-th grade of protection zone; Staged and block is divided by whole power distribution network.

Step 3, according to the partition of the level of protection zone CZij, sets up the oriented graph of a relation of initial power distribution network, namely the oriented graph of a relation of power distribution network be by the protection zone of all levels according to the first order, the second level, the third level ..., i-th grade arrange formation from top to bottom.Oriented graph of a relation: adopt that the protection zone of different stage is connected with each other according to a definite sequence by the arrow with one direction instruction and the figure that forms is called oriented graph of a relation.According to this definition, the simple network of Fig. 3 is converted into oriented graph of a relation, as shown in Figure 4.

Feeder line in step 4 couple CZij carries out segmentation

When including block switch in CZij, by block switch, the element fault in this CZij can be isolated, and then the load restoration because of fault stoppage in transit between power supply and block switch can be powered.Therefore, in feeder line, in different segmentation, the interruption duration of element is different, therefore according to the position of block switch, CZij is divided into different feeder line section (FS).The partiting step of feeder line section is as follows:

First step 4.1 sets all feeder lines in each CZij as the feeder line section of the first level, is designated as FSij1; Combined as can be seen from Fig. 3 and Fig. 5, now, in CZ11, be divided into FS111, CZ, in 21, be divided into FS211, in CZ22, be divided into FS221, in CZ23, be divided into FS231, in CZ31, be divided into FS311.

Step 4.2: direction of tide search block switch when normally running along power distribution network in CZij, when searching the 1st block switch, being revised as the feeder line section of the 2nd level, being designated as FSij2 by feeder lines all for this block switch downstream; Such as, include a normally closed switch in CZ11, so the downstream components of normally closed switch is the feeder line section of the 22nd level, then modifies, and is now divided into FS111, FS112 in CZ11; CZ23 protection zone for another example, as CZ11.

Step 4.3: according to the method for step step 4.2, when searching kth-1 block switch, being revised as the feeder line section of kth level, being designated as FSijk by feeder lines all for this block switch downstream;

Step 4.4 according to step 4.2 and step 4.3 method, travels through the feeder line section of next CZi (j+1) again, until all CZ protection zones all searched to.

Step 5 is obtained the feeder line section information in each protection zone by step 4.1-4.4, existing by feeder line section information insertion to by the oriented graph of a relation of initial power distribution network formed in step 3, obtain the oriented graph of a relation of final power distribution network, as shown in Figure 5.As can be seen from step 5, carry out feeder line segmentation in each protection zone, such as, in first class of protection district, be divided into two feeder line section FS111, FS112.

The dependability parameter equivalence of element in step 6 feeder line layer FS

Because the fault of element in same feeder line layer is all identical on the impact of load point, as shown in Figure 6, Figure 7, therefore in order to simplify the network configuration of reliability assessment, the element identical to load point reliability effect is divided into an equivalent feeder line, this equivalence does not reduce Evaluation accuracy, respectively with equivalent fault rate (λ _e) and equivalence (γ repair time _e) represent the reliability index of this feeder line layer.

${\mathrm{\λ}}_e=\underset{i=1}{\overset{\mathrm{Nc}}{\mathrm{\Σ}}}{\mathrm{\λ}}_i---\left(1\right)$

${\mathrm{\γ}}_e=\frac{\underset{i=1}{\overset{\mathrm{Nc}}{\mathrm{\Σ}}}{\mathrm{\λ}}_i{\mathrm{\γ}}_i}{{\mathrm{\λ}}_e}---\left(2\right)$

In formula: N _cfor the number of element in this equivalent feeder line layer, λ _iand γ _ibe respectively failure rate and the repair time of i-th element in this equivalent feeder line layer.

Step 7 calculates load point failure rate under different condition and average year interruption duration, as shown in Figure 8, Figure 9, and the difference of the oriented graph of a relation of power distribution network for whether containing distributed power source.

Step 7.1: calculate not containing load point failure rate during distributed power source and average year interruption duration.

The calculating of distribution Power System Reliability index is described below in detail: the attached power distribution network network configuration that Figure 10 shows that containing DG community with embodiment.This distribution network load comprises six office building loads (B1, B2, B3, B5, B6, B7), three dormitory loads (D1, D2, D3), a gymnasium load (GM) and a fitness center load (FC).The roof of office building B7 is provided with the photovoltaic unit that rated capacity is 20kW, and except gymnasium and fitness center, all the other nine loads are provided with diesel generating set as stand-by power supply, and when major network breaks down, stand-by power supply is powered to important load.

Suppose, M _ii-th grade of protection zone (CZ _i) number of feeder line section in an interior jth piecemeal, s _ii-th grade of protection zone CZ _iwith the i-th+1 grade protection zone CZ _i+1connected node, N (k) is the protection zone number between load point k to power supply, then containing the failure rate of load point k during distributed power source and average year interruption duration by formula (3) and formula (4) calculating:

$\mathrm{\λ}\left(k\right)=\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=i}{\overset{M_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}+{\mathrm{\λ}}_{\mathrm{mg}}---\left(3\right)$

$U\left(k\right)=\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=1}{\overset{s_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}{\mathrm{\γ}}_{\mathrm{ij}}+\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=s_{i+1}}{\overset{M_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}{t}_{\mathrm{ds}}+{\mathrm{\λ}}_{\mathrm{mg}}{\mathrm{\γ}}_{\mathrm{mg}}---\left(4\right)$

In formula, λ (k) and U (k) is respectively failure rate and the annual interruption duration of load point k; λ _ijand γ _ijit is failure rate and the repair time of a jth feeder line section FS in i-th CZ; t _dsfor the isolated operation time of switch; λ _mgand γ _mgfor failure rate and the repair time of major network.

Step 7.2: calculate containing load point failure rate during distributed photovoltaic power and average year interruption duration

When load point k is connected to distributed photovoltaic power, photo-voltaic power supply contributes to the failure rate and the annual interruption duration that reduce load point.For the load point being connected to photo-voltaic power supply, when major network fault because the timely access of photo-voltaic power supply to the failure rate of load point and can have an impact repair time, therefore the history of photo-voltaic power supply is utilized to go out force data to calculate failure rate λ (k) and average year interruption duration U (k) of load point k when taking into account distributed photovoltaic power, shown in (5) and formula (6):

${\mathrm{\λ}}^{\′}\left(k\right)=\frac{1}{N_{\mathrm{pv}}}\underset{j=1}{\overset{N_{\mathrm{pv}}}{\mathrm{\Σ}}}\frac{\max \{P_{\mathrm{ak}}-P_j,0\}}{P_{\mathrm{ak}}}\mathrm{\λ}\left(k\right)---\left(5\right)$

$U^{\′}\left(k\right)=\frac{1}{N_{\mathrm{pv}}}\underset{j=1}{\overset{N_{\mathrm{pv}}}{\mathrm{\Σ}}}\frac{\max \{P_{\mathrm{ak}}-P_j,0\}}{P_{\mathrm{ak}}}U\left(k\right)---\left(6\right)$

In formula, P _j(j=1,2 ..., N _pV) the exerting oneself in jth hour that be distributed photovoltaic power; N _pVit is total hourage.

Step 7.3: calculate containing load point failure rate during distributed diesel generating set and average year interruption duration

For important power load, often using automatic transfer switch access diesel generating set as stand-by power supply.Because diesel generating set is only start when major network fault, the frequency of power cut that therefore access of diesel generating set can't reduce load point only can reduce the annual interruption duration of load point.When the diesel engine generator group model of consideration two state, the failure rate λ (k) of load point k and average year interruption duration U (k) are calculated by formula (7) and formula (8):

λ " (k)=λ (k) or λ " (k)=λ ' (k) (7)

U " (k)=p _udλ (k) t _di+ p _ddu (k) or U " (k)=p _udλ ' (k) t _di+ p _ddu ' (k) (8)

In formula, t _difor the start-up time of diesel engine generator, p _udand p _ddbe respectively availability factor and the unavailability ratio of diesel generating set.

Step 8: the reliability index calculating distribution system

After obtaining the reliability index of each load point in power distribution network, just can the reliability index of direct computing system according to the definition of the reliability index of distribution system.System System average interruption frequency (SAIFI) refers to the average frequency of power cut that each user is subjected within the unit interval, is represented with the ratio of number of users by user's total degree that has a power failure; System System average interruption duration (SAIDI) refers to the System average interruption duration that user suffered in a year, is represented by the ratio of customer outage hours summation with number of users; User's System average interruption duration (CAIDI) refers to each user each average duration had a power failure in 1 year, is represented by the have a power failure ratio of total degree of customer outage hours summation and user; Average power supply availability factor (ASAI) refers to each user percentage of time that need for electricity is met in a year, and time total by actual power, amount represents with the ratio of amount when requiring to power total; System on average lacks amount of power supply (AENS) and is represented by the ratio of total short of electricity amount with total number of users.

Distribution Power System Reliability index is calculated by formula (9)-(13):

$\mathrm{SAIFI}=\frac{{\mathrm{\Σ}}_{k\∈R}\mathrm{\λ}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIFI}=\frac{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIFI}=\frac{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}---\left(9\right)$ $\mathrm{SAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}U\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{SAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{C}_k}---\left(10\right)$

$\mathrm{ASAI}=\frac{{\mathrm{\Σ}}_{k\∈R}8760C_k-{\mathrm{\Σ}}_{i\∈R}U\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}8760C_k}$ Or $\mathrm{ASAI}=\frac{{\mathrm{\Σ}}_{k\∈R}8760C_k-{\mathrm{\Σ}}_{i\∈R}{U}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}8760C_k}$

Or $\mathrm{ASAI}=\frac{{\mathrm{\Σ}}_{k\∈R}8760C_k-{\mathrm{\Σ}}_{i\∈R}{U}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}8760C_k}---\left(11\right)$

$\mathrm{CAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}U\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}\mathrm{\λ}\left(k\right)C_k}$ Or $\mathrm{CAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′}\left(k\right)C_k}$ Or $\mathrm{CAIDI}=\frac{{\mathrm{\Σ}}_{k\∈R}{U}^{\′\′}\left(k\right)C_k}{{\mathrm{\Σ}}_{k\∈R}{\mathrm{\λ}}^{\′\′}\left(k\right)C_k}---\left(12\right)$

$\mathrm{AENS}=\frac{{\mathrm{\Σ}}_{k\∈R}{P}_{\mathrm{ak}}U\left(k\right)}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{AENS}=\frac{{\mathrm{\Σ}}_{k\∈R}{P}_{\mathrm{ak}}{U}^{\′}\left(k\right)}{{\mathrm{\Σ}}_{k\∈R}{C}_k}$ Or $\mathrm{AENS}=\frac{{\mathrm{\Σ}}_{k\∈R}{P}_{\mathrm{ak}}{U}^{\′\′}\left(k\right)}{{\mathrm{\Σ}}_{k\∈R}{C}_k}---\left(13\right)$

In formula, λ (k) and U (k) is respectively failure rate and the annual interruption duration of load point k when not containing distributed power source, λ ' (k) and U ' (k) are respectively failure rate containing load point k during distributed photovoltaic power and annual interruption duration, λ " (k) and U " (k) is respectively failure rate containing load point k during distributed diesel generating set and annual interruption duration, is failure rate and the annual interruption duration of load point k corresponding in formula (3)-(10); C _kit is the number of users that a kth load point connects; P _akfor a kth load point power; R is load point set.

According to the reliability basic data that step 1 gathers, calculate not as shown in table 1 below containing distribution Power System Reliability index calculate result result during distributed power source according to formula (9)-(13):

Table 1

Building title	SAFI	SAIDI	ASAI(％)	AENS
					B1	1.0765	7.4127	99.9154	498.4270
B2	1.0782	7.4774	99.9146	537.5650
					B3	1.0775	7.5019	99.9144	394.2440
B5	1.0775	7.4704	99.9147	1042.1000
					B6	1.0782	7.4774	99.9146	495.0040
B7	1.0775	7.5019	99.9144	848.6900
					D1	1.0800	7.6839	99.9123	659.6120
D2	1.0800	7.6839	99.9123	318.9080
					D3	1.0800	7.6839	99.9123	612.3560
GM	1.0800	7.6839	99.9123	218.7610
					FC	1.0800	7.6839	99.9123	670.8050
Whole system	1.0784	7.5430	99.9139	578.123

On average scarce amount of power supply (AENS) is higher for system System average interruption frequency (SAIFI), system System average interruption duration (SAIDI), user's System average interruption duration (CAIDI), system as can be seen from Table 1, and stability, the power supply reliability of distribution network system are lower; Average power supply availability factor (ASAI) is higher, and the power supply performance of distribution network system is better.

Calculate containing distribution Power System Reliability index calculate result during distributed power source as shown in table 2 below, because distributed power source is only arranged on B7, therefore only improve the reliability index of B7 building after distributed power source access, the reliability index of other buildings is identical with above-mentioned computational methods.

Table 2

Building title	SAFI	SAIDI	ASAI(％)	AENS	CR ASAI(％)
						B7	1.06800	7.4355	99.9151	843.927	0.0007
Whole system	1.07753	7.5369	99.9140	577.690	0.0001

As shown in table 3 below containing distribution Power System Reliability index calculate result during diesel generating set:

Table 3

Building title	SAFI	SAIDI	ASAI(％)	AENS	CR ASAI(％)
						B1	1.07648	5.60104	99.9361	453.607	0.0207
B2	1.07823	6.01542	99.9313	432.011	0.0167
						B3	1.07753	5.66842	99.9353	386.396	0.0209
B5	1.07753	5.03605	99.9425	496.948	0.0278
						B6	1.07823	5.04077	99.9425	235.016	0.0279
B7	1.06800	4.99091	99.9430	499.209	0.0286
						D1	1.07998	5.17982	99.9409	304.183	0.0286
D2	1.07998	5.17982	99.9409	242.658	0.0286
						D3	1.07998	5.17982	99.9409	476.159	0.0286
GM	1.07998	7.68390	99.9123	218.761	0
						FC	1.07998	7.68390	99.9123	670.805	0
Whole system	1.07753	5.52559	99.9369	399.156	0.0230

Claims (1)

1. based on a distribution network reliability evaluation method for oriented graph of a relation, it is characterized in that: comprise the following steps:

A: gather the structured data of power distribution network to be assessed, electric parameter data and reliability parameters data bank;

B: the data gathered according to steps A, carries out piecemeal and classification to power distribution network network configuration;

Based on the difference of different elements fault effects in power distribution network, power distribution network is carried out piecemeal and classification in accordance with the following steps:

B1: the direct first section of circuit breaker be connected with major network bus is divided into first order circuit breaker, and is designated as CB11;

B2: under system failure running status, be starting point based on Depth Priority Algorithm with CB11, start on the feeder line at CB11 place along direction of tide search element, the end searching a circuit breaker or search feeder line then stops the party's search upwards, the search on other directions is proceeded again, until all direction search terminate from CB11; The protection zone of all element composition CB11 then searched in this process forms a block, and is called first class of protection district, is designated as CZ11;

B3: the method utilizing step B1 and B2, specify that the circuit breaker of the downstream direction of tide be directly connected with CZ (i-1) (j-1) is called i-th grade of circuit breaker, and protection zone corresponding to i-th grade of circuit breaker is called jth level protection zone, search obtains other circuit breaker CBij and respective protection zone CZij thereof, wherein, if CBij represents the jth circuit breaker in i-th grade of protection zone; CZij represents the jth block in i-th grade of protection zone; Staged and block is divided by whole power distribution network;

C: according to the partition of the level of protection zone CZij, sets up the oriented graph of a relation of initial power distribution network, namely the oriented graph of a relation of power distribution network be by the protection zone of all levels according to the first order, the second level, the third level ..., i-th grade arrange formation from top to bottom;

D: segmentation is carried out to the feeder line in CZij; CZij is divided into different feeder line section FS by the position according to block switch, and partiting step is as follows:

D1: first set feeder lines all in CZij as the feeder line section of the first level, be designated as FSij1;

D2: direction of tide search block switch when normally running along power distribution network in CZij, when searching the 1st block switch, being revised as the feeder line section of the 2nd level, being designated as FSij2 by feeder lines all for this block switch downstream;

D3: according to the method for step D2, when searching kth-1 block switch, being revised as the feeder line section of kth level, being designated as FSijk by feeder lines all for this block switch downstream; Continue search block switch, block switches all in CZij is all searched and till segmentation;

E: obtained the feeder line section information in each protection zone by step D2 and D3, in the existing oriented graph of a relation of power distribution network set up by feeder line section information insertion step C in each protection zone, obtains the oriented graph of a relation of final power distribution network;

F: the dependability parameter equivalence of element in feeder line section;

Because the fault of element in same feeder line section is all identical on the impact of load point, so the element identical to load point reliability effect is divided into an equivalent feeder line, respectively with equivalent fault rate λ _ewith equivalence γ repair time _erepresent the reliability index of this feeder line section;

${\mathrm{\λ}}_e=\underset{i=1}{\overset{\mathrm{Nc}}{\mathrm{\Σ}}}{\mathrm{\λ}}_i---\left(1\right)$

${\mathrm{\γ}}_e=\frac{\underset{i=1}{\overset{\mathrm{Nc}}{\mathrm{\Σ}}}{\mathrm{\λ}}_i{\mathrm{\γ}}_i}{{\mathrm{\λ}}_e}---\left(2\right)$

In formula: NC is the number of element in this equivalent feeder line section, λ _iand γ _ibe respectively failure rate and the repair time of i-th element in this equivalent feeder line section;

G: the failure rate and the annual interruption duration that calculate distribution network load point according to the oriented graph of a relation of final power distribution network;

G1: when not containing distributed power source in system, the failure rate of load point and annual interruption duration, the i.e. calculating of the reliability index of load point;

Suppose, Mi is the number of the feeder line section in a jth piecemeal of i-th grade of protection zone CZij, and si is i-th grade of protection zone CZij and the i-th+1 grade protection zone CZ _i+1connected node, N (k) is the protection zone number between load point k to power supply, then (3) and (4) the failure rate of load point k and annual interruption duration are calculated by formula:

$\mathrm{\λ}\left(k\right)=\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=i}{\overset{M_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}+{\mathrm{\λ}}_{\mathrm{mg}}---\left(3\right)$

$U\left(k\right)=\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=1}{\overset{s_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}{\mathrm{\γ}}_{\mathrm{ij}}+\underset{i=1}{\overset{N\left(k\right)}{\mathrm{\Σ}}}\underset{j=s_{i+1}}{\overset{M_i}{\mathrm{\Σ}}}{\mathrm{\λ}}_{\mathrm{ij}}{t}_{\mathrm{ds}}+{\mathrm{\λ}}_{\mathrm{mg}}{\mathrm{\γ}}_{\mathrm{mg}}---\left(4\right)$

In formula, λ (k) and U (k) is respectively failure rate and the annual interruption duration of load point k; λ _ijand γ _ijit is failure rate and the repair time of a jth feeder line section FSij in i-th CZij; t _dsfor the isolated operation time of switch; λ _mgand γ _mgfor failure rate and the repair time of major network;

G2: when calculating containing distributed photovoltaic power, the failure rate of load point and average year interruption duration;

The history of distributed power source is utilized to go out force data to determine failure rate λ ' (k) and average year interruption duration U ' (k) of load point k, as (5), (6) formula is depicted as:

${\mathrm{\λ}}^{\′}\left(k\right)=\frac{1}{N_{\mathrm{pv}}}\underset{j=1}{\overset{N_{\mathrm{pv}}}{\mathrm{\Σ}}}\frac{\max \{P_{\mathrm{ak}}-P_j,0\}}{P_{\mathrm{ak}}}\mathrm{\λ}\left(k\right)---\left(5\right)$

${\mathrm{U\λ}}^{\′}\left(k\right)=\frac{1}{N_{\mathrm{pv}}}\underset{j=1}{\overset{N_{\mathrm{pv}}}{\mathrm{\Σ}}}\frac{\max \{P_{\mathrm{ak}}-P_j,0\}}{P_{\mathrm{ak}}}U\left(k\right)---\left(6\right)$

In formula, P _j(j=1,2 ..., N _pV) the exerting oneself in jth hour that be distributed photovoltaic power; N _pVit is total hourage; P _akfor the power of load point k;

G3: calculate containing load point failure rate during distributed diesel generating set and average year interruption duration;

Because diesel generating set is only start when major network fault, the frequency of power cut that therefore access of diesel generating set can't reduce load point only can reduce the annual interruption duration of load point; Load point k failure rate λ " (k) and average year interruption duration U " (k) (7) (8) calculated with formula by formula:

(k)=λ ' (k) (7) for λ " (k)=λ (k) or λ "

U " (k)=p _udλ (k) t _di+ p _ddu (k) or U " (k)=p _udλ ' (k) t _di+ p _ddu ' (k) (8)

In formula, t _difor the start-up time of diesel engine generator, P _udand P _ddbe respectively availability factor and the unavailability ratio of diesel generating set;

H: the reliability index calculating distribution network system, exports result of calculation;

Distribution network system reliability index is calculated by following formula:

In formula, λ (k) and U (k) is respectively failure rate and the annual interruption duration of load point k when not containing distributed power source, λ ' (k) and U ' (k) are respectively failure rate containing load point k during distributed photovoltaic power and annual interruption duration, λ " (k) and U " (k) is respectively failure rate containing load point k during distributed diesel generating set and annual interruption duration, is failure rate and the annual interruption duration of load point k corresponding in formula (3)-(10); C _kit is the number of users that a kth load point connects; P _akfor a kth load point power; R is load point set;

SAIFI refers to system System average interruption frequency, i.e. the average frequency of power cut that is subjected within the unit interval of each user, is represented with the ratio of number of users by user's total degree that has a power failure; SAIDI refers to system System average interruption duration, and namely the System average interruption duration that suffered in 1 year of user, is represented by the ratio of customer outage hours summation with number of users; CAIDI refers to user's System average interruption duration, i.e. each user each average duration had a power failure in 1 year, is represented by the have a power failure ratio of total degree of customer outage hours summation and user; ASAI refers on average power availability factor, i.e. each user percentage of time that need for electricity is met in a year, and time total by actual power, amount represents with the ratio of amount when requiring to power total; AENS refers to that system on average lacks amount of power supply, is namely represented by the ratio of total short of electricity amount with total number of users;

I: the result calculated according to step H, the value according to ASAI is larger, and reliability is higher; The value of SAIFI, SAIDI, CAIDI and AENS is less, and reliability is higher, thus the reliability of assessment distribution network system.