CN109918739B - Distribution lines model suitable for hierarchical protection configuration - Google Patents
Distribution lines model suitable for hierarchical protection configuration Download PDFInfo
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Abstract
A distribution line model suitable for hierarchical protection configuration abstracts a distribution line into four parts, namely a 10kV bus, a lead, a switch and a distribution transformer. Each part is expressed by a specific unified numerical structure to form a unified standard information model, and the impedance at any position and the total capacity of the distribution transformer in any interval are calculated according to the model. The model abstracts the common characteristics of the uniform distribution lines based on the most important characteristics of the distribution lines to form a uniform information model. The distribution line model suitable for hierarchical protection configuration provided by the invention can realize standardization of the information model of the distribution line, provides an information basis for forming a unified algorithm for distribution line hierarchical protection configuration calculation, and is beneficial to realizing stylized input of distribution line information, batch import and storage of line information and quick acquisition of a hierarchical protection configuration scheme.
Description
Technical Field
The invention relates to a distribution line model suitable for hierarchical protection configuration, and belongs to the technical field of power distribution.
Background
In order to realize the orderly tripping of the switches at all levels when the distribution line has a fault, a hierarchical protection configuration method is adopted to configure the switch positions and the fixed values of the switches.
The hierarchical protection configuration method comprises the following steps;
(1) Grading number: according to the national standard, the action time of the backup protection of the 220kV main transformer is less than 2s, the difference time of the upper and lower protection levels is not less than 0.2s, the action time of the 10kV line end protection of the 35kV transformer substation is only 0.5s-0.7s, and two-level protection can be set; the transformer substations of 110kV and 220kV have 0.7s-1.2s, and can be provided with three-level protection.
(2) The method comprises the steps of carrying out graded protection configuration, setting a second-stage protection at a proper position of a circuit for a substation outgoing switch, setting a third-stage protection at a proper position of the rear side of the second-stage protection, wherein short-circuit current needs to be considered at the position of each-stage protection, and the current depends on system impedance and circuit parameters of the circuit.
Due to the fact that the structure of the distribution line is complex and changeable, the distribution line model suitable for hierarchical protection configuration lacks, the hierarchical protection configuration needs to carry out parameter collection and calculation on each line independently, and a unified algorithm cannot be formed to carry out batch rapid calculation and large-scale application of the hierarchical protection configuration on a large number of lines.
Disclosure of Invention
The invention aims to provide a distribution line model suitable for hierarchical protection configuration in order to realize rapid and automatic batch processing of the hierarchical protection configuration of the distribution line.
The distribution line model is suitable for hierarchical protection configuration, ignores the differences of types, structures, directions, trends and the like of different distribution lines, and abstracts the distribution lines into four parts, namely 10kV buses, wires, switches and distribution transformers based on the most important characteristics of the distribution lines, namely that any distribution line is connected to the 10kV buses and is composed of the wires, the switches, the distribution transformers and the like; each part is expressed by a specific unified numerical structure to form a unified standard information model, and a calculation method of impedance at any position and distribution transformation total capacity in any interval is provided according to the model.
The 10kV bus is composed of two numerical structures: system resistance R in (1) maximum mode at 10kV bus d And the system reactance X in the maximum mode d (ii) a (2) System resistance R in minimum mode s And system reactance X in a minimum manner s 。
The lead comprises a main line, branch lines and secondary lines;
the trunk line is characterized in that each wire type is a section according to the type of the wire between the starting end and the tail end, and the number of the sections is determined by the number of times of wire change, the wire type and the length of the main line; the main line is provided with N types of leads which are connected in series from the starting end to the tail end in sequence, each type of lead is divided into one section, the main line is divided into N sections, and the ith part of the section is the data structure D for the model of the ith section of lead of the main line i Represents:
D i ＝(a i ,b i ,l i )
in the formula, a i Resistance per unit length (ohm/km) of the ith section of the main line wire; b i The unit length reactance of the ith section of the main line is Euro/km; l i The unit is km, which is the length of the ith section of lead of the trunk line; total length of trunk line L D Is the sum of the lengths of all the segmented conductors of the trunk line, namely:
the backbone can thus be represented by data structure D: d = { D 1 ,D 2 ,…,D N }；
The branch lines are connected with the trunk line, and the number of the branch lines is multiple; thus, a branch line may in some cases have multiple data structures, and each data structure is incremented by an amount of a location, indicating where the branch line connects to the trunk line;
a branch line connected to the trunk line and denoted by F t (ii) a Conducting wires connected in series from beginning to endNumber of types N f Each type of wire is divided into one section, and the branch line is divided into N f Data structure F for model of j-th part of section, i.e. j-th section of branch line j Represents: f j ＝(a j ,b j ,l j )；
In the formula, a j The resistance is the unit length resistance of the j section of the conductor of the branch line, and the unit is Euro/km; b j The unit length reactance of the j section of the wire of the branch line is Euro/km; l j The length of the jth section of the wire of the branch line is km; branch line F t Total length L F Is the sum of the lengths of all the segmented wires of the branch line, namely:
therefore, the data structure F for the branch line t Represents:
in the formula, L t Is a branch line F t Length from the beginning of the trunk, L, of the trunk contact t Satisfy 0 < L t ＜L D ，L D Total length of trunk line, N f Is a branch line F t The number of the types of the wires which are sequentially connected in series from the starting end to the tail end;
the secondary branch is connected with the branch line, and the data structure expressing the secondary branch is provided with one more data relative to the branch line and used for indicating the branch line connected with the secondary branch;
is connected to a branch line F t Primary branch of (D), denoted by C r (ii) a The number of the types of the conducting wires which are sequentially connected in series from the beginning end to the end is N c Each type of wire is divided into one segment, and the branch line is divided into N c A segment; wherein, the data structure C for model of k-th section of wire of branch line k Represents: c k ＝(a k ,b k ,l k )；
In the formula, a k Resistance per unit length of k-th section of wire of secondary branch line in ohm/km, b k For the kth section of the secondary branchReactance per unit length of wire, in ohm/km; l. the k The unit of the length of the kth section of lead of the secondary branch is km; secondary branch line C r Total length L C The sum of all segment wire lengths for the secondary branch, i.e.:
data structure C for secondary branch line r Represents:
wherein t is the serial number of the branch line connected with the secondary branch line, L r Is a secondary branch C r And the branch line F connected thereto t Length of contact from beginning of branch line, L r Satisfy the requirement of
N c Is a secondary branch C r The number of the conductor types connected in series from the starting end to the tail end.
The switch comprises a switch position and a switch constant value; the position of the switch is determined by the number of the wire where the switch is located and the distance between the switch and the initial end of the wire; the switch constant value comprises a current constant value and a time constant value of an overcurrent section I, an overcurrent section II and an overcurrent section III; switch available data structure K s Represents;
the switch on the main line D is represented as: k s ＝{D,L DKs ,(I 1 ,t 1 ),(I 2 ,t 2 ),(I 3 ,t 3 )}；
Wherein D is a trunk line number indicating that the switch is located in the trunk line, L DKs Distance of switch position from beginning of main line, L DKs Satisfy the requirements of
(I 1 ,t 1 )、(I 2 ,t 2 )、(I 3 ,t 3 ) Respectively setting the current and time values of the switch overcurrent I section, the switch overcurrent II section and the switch overcurrent III section;
the branch line F t Upper openingOff is expressed as: k is s ＝{F t ,L FKs ,(I 1 ,t 1 ),(I 2 ,t 2 ),(I 3 ,t 3 )}；
In the formula, F t For branch line reference, it indicates that the switch is located at branch line F t C, removing; l is FKs Distance between switch position and beginning of branch line, L FKs Satisfy the requirement of
The distance between the switch on the branch line and the starting end of the main line is L FKs +L t ，L t Is a branch line F t A length from a trunk line starting end of a trunk line contact point; (I) 1 ,t 1 )、(I 2 ,t 2 )、(I 3 ,t 3 ) Respectively setting the current values and the time values of the switch overcurrent I section, the switch overcurrent II section and the switch overcurrent III section;
the secondary branch C r The switches above are represented as: k s ＝{C r ,L CKs ,(I 1 ,t 1 ),(I 2 ,t 2 ),(I 3 ,t 3 )}；
In the formula, C r Is a branch line number indicating that the switch is located in the minor branch C r Upper, L CKs Distance of switch position from beginning of minor branch, L CKs Satisfy the requirements of
The switch on the secondary branch is at a distance L from the start of the main line CKs +L r +L t ，L r Is a secondary branch C r And the branch line F connected thereto t Length of contact from beginning of branch line, L t Is a branch line F t The length from the trunk start of the trunk contact point. (I) 1 ,t 1 )、(I 2 ,t 2 )、(I 3 ,t 3 ) The current fixed value and the time fixed value of the switch overcurrent I section, the switch overcurrent II section and the switch overcurrent III section are respectively.
The distribution transformer comprises a distribution transformer position and a distribution transformer capacity; the distribution position is determined by the number of the lead where the distribution transformer is located and the distance from the initial end of the lead; what is neededThe distribution capacity is the sum of one or more distribution capacities hooked at a certain position, and the unit is kVA; data structure for distribution transformation P b It is shown that,
the switch on the main line D is represented as: p is b ＝{D,L DPb ,Q Pb }；
The branch line F t The distribution of the upper is expressed as: p b ＝{F t ,L FPb ,Q Pb }；
In the formula, F t Is a branch line number indicating that the distribution transformer is located on branch line F t Upper, L FPb Is the distance between the distribution position and the beginning of the branch line, L FPb Satisfy the requirement of
The distance between the distribution transformer on the branch line and the starting end of the trunk line is L FPb +L t ，L t Is a branch line F t A length from a trunk line start end of a trunk line contact point; q Pb To a distribution transformation capacity;
the secondary branch C r The distribution of (d) is represented as: p is b ＝{C r ,L CPb ,Q Pb }；
In the formula, C r Is a branch line number indicating that the distribution transformer is located on the secondary branch line C r Upper, L CPb Is the distance between the distribution position and the beginning of the secondary branch line, L CPb Satisfy the requirement of
The distance between the distribution transformer on the secondary branch line and the start end of the main trunk line is L CPb +L r +L t ，L r Is a secondary branch C r And the branch line F connected thereto t Length of contact from beginning of branch line, L t Is a branch line F t A length from a trunk line start end of a trunk line contact point; q Pb To distribute capacity.
The impedance at any position is the impedance required by the graded protection configuration, and the calculation method is as follows:
(1) The distance between a certain point on the trunk line and the starting end is l, and the point is positioned on the ith section of the trunk line, namely
The resistance and reactance of the conductor between this point and the beginning of the trunk are then a function of the length l, expressed respectively as:
in the formula, R Z (l)、X Z (l) Respectively is a resistance function and a reactance function of a main line wire at a position which is l away from the starting end of the main line on the main line; v is an indication serial number; i is the main line conductor subsection number; ai. bi is the unit length resistance and reactance of the ith section of the main line wire respectively; l i The length of the ith section of lead of the main line is long;
(2) Branch line F t The distance between the last point and the beginning end of the branch line is l, and the point is arranged on the jth section of the branch line, namely
l j For the length of the j-th section of the branch line, the resistance and reactance of all the wires between the point and the beginning of the main line are functions of the length l and are respectively expressed as:
in the formula, R F (l)、X F (l) Respectively a conductor resistance function and a reactance function counted from the starting end of the trunk line at a distance of l from the starting end of the branch line on the branch line; l is t Is a branch line F t A length from a trunk line starting end of a trunk line contact point; v is an indication serial number; j is a branch line F t Conducting wire subsection numbering; aj. bj is the unit length resistance and reactance of the j section of the lead of the branch line respectively; l j The length of the j section of the wire of the branch wire is;
(3) Secondary branch line C r The distance between the last point and the starting end of the secondary branch line is l, and the point is arranged on the kth section of the branch line, namely
l k The length of the kth section of wire of the branch wire is; the resistance and reactance of all the conductors between this point and the beginning of the trunk are then a function of the length l, expressed respectively as:
in the formula, R C (l)、X C (l) Are respectively the minor branch C r The resistance function and the reactance function of the wire from the starting end of the main trunk line at the position which is at the distance of l from the starting end of the secondary branch line; l is a radical of an alcohol t Is a branch line F t A length from a trunk line start end of a trunk line contact point; l is a radical of an alcohol r Is the minor branch C r And the branch line F connected thereto t The length of the contact from the beginning end of the branch line; v is an indication sequence number; k is the minor branch C r Conducting wire subsection numbering; ak. bk is the unit length resistance and reactance of the kth section of wire of the secondary branch line respectively; l k The length of the kth section of wire of the secondary branch line;
the system impedance at any position in the maximum mode and the system impedance at the minimum direction are obtained by respectively superposing the total resistance and the total reactance of the lead at any position with the corresponding resistance reactance in the maximum mode and the minimum mode; the system resistance and reactance under the maximum mode of a certain position l of the secondary branch line are respectively as follows:
R d (l)＝R d +R C (l)，X d (l)＝X d +X C (l)
in the formula, R d The system resistance and X of a 10kV bus in the maximum mode d The system reactance is at the position of a 10kV bus in a maximum mode; the total impedance here is:
the method for calculating the total capacity of the distribution transformer in any interval comprises the following steps:
(1) The total capacity of the distribution transformation between the trunk line/and the origin is a function of the length l and is expressed as:
in the formula, L DPb Distance of distribution position from beginning of trunk line, Q Pb Is the distribution capacity;
(2) The total capacity of the distribution transformation between the branch line/and the beginning is a function of the length l and is expressed as:
in the formula, L FPb The distance between the distribution position and the beginning of the branch line, Q Pb Is the distribution capacity;
(3) The total capacity of the distribution transformation between the secondary branch l and the beginning of the secondary branch is a function of the length l and is expressed as:
in the formula, L CPb The distance between the distribution position and the beginning of the branch line, Q Pb Is the distribution capacity;
(4) On the main trunk line 1 Is at and l 2 A (l) 1 <l 2 ) The total capacity of the distribution transformer is as follows:
Q Z (l 1 ,l 2 )＝Q Z (l 2 )-Q Z (l 1 )
in the formula, L CPb Distance of distribution position from beginning of trunk line, Q Pb To a distribution transformation capacity;
(5) On the main trunk line 2 At the endThe total capacity of the distribution transformer is as follows:
Q Z (l 2 ,L D )＝Q Z (L D )-Q Z (l 2 )
in the formula, L D Total length of trunk line, L CPb Distance of distribution position from beginning of trunk line, Q Pb To distribute capacity.
The invention abstracts the distribution line into four parts of a 10kV bus, a lead, a switch and a distribution transformer, is not artificially specified, but is based on the most important technical characteristics of the distribution line, and abstracts the common characteristics of the uniform distribution line by utilizing the natural law of the distribution line to form a uniform standard information model.
The method has the advantages that the model abstracts the common characteristics of the uniform distribution lines based on the most important characteristics of the distribution lines to form a uniform information model. The model provided by the invention can realize the standardization of the information model of the distribution line, provides an information basis for forming a unified algorithm for the distribution line hierarchical protection configuration calculation, and is beneficial to realizing the stylized input of the distribution line information, the batch import and storage of the line information and the quick acquisition of the hierarchical protection configuration scheme.
Drawings
Fig. 1 is a schematic diagram of a 10kV distribution line model.
Detailed Description
The specific implementation mode of the invention is as follows:
the embodiment of the invention provides a distribution line model suitable for hierarchical protection configuration, 10kV distribution lines are abstracted according to protection correlation and the characteristics of the distribution lines, and any 10kV distribution line comprises four parts: 10kV bus, wire, switch and distribution transformer, each of these four parts is composed of assigned numerical values. As shown in fig. 1.
1. 10kV bus
The model 10kV bus consists of two values: the system resistance R of the 10kV bus in the (1) maximum mode d And the system reactance X in the maximum mode d And (2) System resistance R in minimum mode s And in a minimum modeSystem reactance X s 。
2. The wire of the embodiment comprises three parts: the main trunk line (1), the branch line (2) and the secondary branch line (3) are connected in series.
Related relations exist among three parts of wires: wherein the number of the main lines is 1; the number of the branch lines can be 0, can also be 1 or more than 1, and the branch lines are connected to the main line; the secondary branches are connected to the branch lines, and the number of the secondary branches connected to each branch line can be larger than 1.
(1) Main trunk line
The main line is a section of each wire type according to the type of the wire between the starting end and the tail end, and the number of the sections is determined by the number of times of wire change on the main line, the wire type and the length. Assuming that the main line is serially connected with N types of wires from the beginning to the end, each type of wire is divided into one segment, the main line is divided into N segments, and the ith part, namely the data structure D for the model of the ith segment of wire of the main line i Represents: d i ＝(a i ,b i ,l i )；
In the formula, a i Resistance per unit length (ohm/km), b for the ith section of main line wire i Reactance per unit length (ohm/km), l, of the i-th section of the main line i Length (km) of the ith section of wire of the main line, total length L of the main line D Is the sum of the lengths of all the segmented conductors of the trunk line,
namely:
the backbone can therefore be represented by data structure D: d = { D = 1 ,D 2 ,…,D N }；
(2) Branch line
The branch lines are also represented by a data structure, similar to the trunk line, except that the branch lines are connected to the trunk line, and may be multiple in number. Thus, a branch line may in some cases have multiple data structures, and each data structure is incremented by a location amount indicating where the branch line connects to the trunk line.
Suppose a branch line (denoted F) connected to the trunk line t ) From the beginning to the endThe number of the types of the conducting wires connected in series in sequence is N f Each type of wire is divided into one segment, and the branch line is divided into N f Data structure F for model of j-th part of section, i.e. j-th section of branch line j Represents: f j ＝(a j ,b j ,l j )
In the formula, a j Resistance per unit length (ohm/km), b of j section conductor of branch line j Reactance per unit length (ohm/km), l of j-th section of conductor of branch line j The length (km) of the j-th section of the wire of the branch line. Branch line F t Total length L F Is the sum of the lengths of all the segmented conductors of the branch line,
namely:
the branch line usable data structure F t Represents:
in the formula, L t Is a branch line F t Length from the beginning of trunk, L, of contact with trunk t Satisfy 0 < L t ＜L D ，L D Total length of trunk line, N f Is a branch line F t The number of the types of the conducting wires which are connected in series from the beginning to the end.
(3) Sub branch line
The secondary branch is also represented by a data structure, similar to the branch line, except that the secondary branch is connected to the branch line, which is indicated clearly. The data structure expressing the secondary branch is therefore one more data with respect to the branch for indicating the branch line to which the junction is connected.
Assumed to be connected to a branch line F t Primary branch (denoted as C) r ) The number of the types of the conducting wires which are sequentially connected in series from the beginning end to the end is N c Each type of wire is divided into one section, and the branch line is divided into N c Segment, wherein data structure C for model of k-th segment wire of branch line k Represents:
C k ＝(a k ,b k ,l k )
in the formula, a k Resistance per unit length (ohm/km), b for the kth section of wire of the secondary branch line k Reactance per unit length (ohm/km), l, of the kth conductor of the secondary branch line k The length (km) of the kth segment of the wire of the secondary branch. Minor branch C r Total length L C The sum of all segment wire lengths for the secondary branch,
namely:
therefore, the sub-branch available data structure C r Represents:
wherein t is the serial number of the branch line connected with the secondary branch line, L r Is a secondary branch C r And the branch line F connected thereto t Length of contact from beginning of branch line, L r Satisfy the requirements of
N c Is a secondary branch C r The number of the types of the conducting wires which are connected in series from the beginning to the end.
3. The switch includes: (1) the position of the switch; and (2) switching to a fixed value.
The switches are distributed on the wires and can be arranged on a main line, a branch line or a secondary branch line, and the positions can be determined by the serial number of the wire where the switch is arranged and the distance from the starting end of the wire; the switch constant value comprises a current constant value and a time constant value of overcurrent I, II and III sections. Switch available data structure K s Representation, where the switches on the trunk line D are represented as: k is s ＝{D,L DKs ,(I 1 ,t 1 ),(I 2 ,t 2 ),(I 3 ,t 3 )}，
Wherein D is a trunk line number indicating that the switch is located in the trunk line, L DKs Distance of switch position from the beginning of main line, L DKs Satisfy the requirement of
(I 1 ,t 1 )、(I 2 ,t 2 )、(I 3 ,t 3 ) The current fixed value and the time fixed value of the switch overcurrent I section, the switch overcurrent II section and the switch overcurrent III section are respectively.
Branch line F t The upper switches are represented as: k is s ＝{F t ,L FKs ,(I 1 ,t 1 ),(I 2 ,t 2 ),(I 3 ,t 3 )}，
In the formula, F t For branch line reference numerals, it is indicated that the switch is located at branch line F t Upper, L FKs Distance between switch position and beginning of branch line, L FKs Satisfy the requirement of
The switch on the branch line has a distance L from the start end of the trunk line FKs +L t ，L t Is a branch line F t The length from the trunk start of the trunk contact point. (I) 1 ,t 1 )、(I 2 ,t 2 )、(I 3 ,t 3 ) The current fixed value and the time fixed value of the switch overcurrent I section, the switch overcurrent II section and the switch overcurrent III section are respectively.
Secondary branch line C r The switches above are represented as: k s ＝{C r ,L CKs ,(I 1 ,t 1 ),(I 2 ,t 2 ),(I 3 ,t 3 )}，
In the formula, C r Is a branch line number indicating that the switch is located in the minor branch C r Upper, L CKs Is the distance between the switch position and the beginning of the secondary branch, L CKs Satisfy the requirement of
The switch on the secondary branch is at a distance L from the start of the main line CKs +L r +L t ，L r Is a secondary branch C r And the branch line F connected thereto t Length of contact from beginning of branch line, L t Is a branch line F t The length from the trunk start of the trunk contact point. (I) 1 ,t 1 )、(I 2 ,t 2 )、(I 3 ,t 3 ) Are respectively provided withThe current setting value and the time setting value of the overcurrent I section, the overcurrent II section and the overcurrent III section of the switch are obtained.
4. The distribution transformer comprises: (1) a transformation position; and (2) distributing the variable capacity.
The distribution transformer is distributed on the lead and can be arranged on a main line, a branch line or a secondary branch line, and the position can be determined by the number of the lead where the distribution transformer is arranged and the distance from the starting end of the lead; the distribution capacity is the sum of one or more distribution capacities hooked at a certain position in a unit kVA.
Data structure P available for distribution b And (4) showing.
Wherein the switch on the trunk line D is represented as: p is b ＝{D,L DPb ,Q Pb }，
Wherein D is a trunk line number indicating that the distribution transformer is located in the trunk line, L DPb Is the distance between the distribution position and the start of the trunk line, L DPb Satisfy the requirement of
Q Pb To distribute capacity.
Branch line F t The distribution of (d) is represented as: p b ＝{F t ,L FPb ,Q Pb }，
In the formula, F t Is a branch line number indicating that the distribution transformer is located on branch line F t Upper, L FPb Is the distance between the distribution position and the beginning of the branch line, L FPb Satisfy the requirement of
The distance between the distribution transformer on the branch line and the start end of the trunk line is L FPb +L t ，L t Is a branch line F t The length from the trunk start of the trunk contact point. Q Pb To distribute capacity.
Secondary branch line C r The distribution of (d) is represented as: p is b ＝{C r ,L CPb ,Q Pb }，
In the formula, C r Is a branch line number indicating that the distribution transformer is located on the secondary branch line C r Upper, L CPb Is the distance between the distribution position and the beginning of the secondary branch line, L CPb Satisfy the requirement of
The distance between the distribution transformer on the secondary branch line and the start end of the main trunk line is L CPb +L r +L t ，L r Is the minor branch C r And the branch line F connected thereto t Length of contact from beginning of branch line, L t Is a branch line F t The length from the trunk start of the trunk contact point. Q Pb To distribute capacity.
5. Method for calculating impedance at arbitrary position
Based on the distribution line model, the impedance required by the hierarchical protection configuration can be obtained, and the calculation method comprises the following steps:
(1) The distance between a certain point on the trunk line and the starting end is l (if the point is positioned on the ith section of the trunk line, namely
The resistance and reactance of the conductor between this point and the start of the trunk are then a function of the length l, expressed respectively as:
in the formula, R Z (l)、X Z (l) Respectively a resistance function and a reactance function of a main line wire at a distance of l from the starting end of the main line on the main line, v is an indication serial number, i is a main line wire segment number, ai and bi are respectively a unit length resistance and a unit length reactance of an ith segment of the main line wire, l i Is the length of the ith segment of main line wire.
(2) Branch line F t The distance between the point and the beginning of the branch line is l (if the point is located at the jth section of the branch line, that is to say
l j The length of the j-th section of the branch line), the resistance and reactance of all the wires between the point and the beginning of the trunk line are functions of the length l and are respectively expressed as:
in the formula, R F (l)、X F (l) Respectively, a conductor resistance function and a reactance function from the start end of the trunk line at a distance of L from the start end of the branch line, L t Is a branch line F t The length from the trunk line start of the trunk line at the trunk line contact point, v is the designation number, j is the branch line F t The conducting wire is numbered in sections, aj and bj are respectively the resistance and reactance per unit length of the j-th section of conducting wire of the branch line, l j Is the length of the j section of the wire of the branch line.
(3) Secondary branch line C r The distance between the point and the starting end of the secondary branch line is l (if the point is located on the kth section of the branch line, that is to say
l k Is the length of the kth conductor of the branch line), the resistance and reactance of all the conductors between the point and the beginning of the trunk line are functions of the length l, and are respectively expressed as:
in the formula, R C (l)、X C (l) Are each a minor branch C r The resistance function and reactance function of the conductor line from the start of the trunk line at a distance L from the start of the secondary branch line t Is a branch line F t Length from the beginning of trunk, L, of contact with trunk r Is a secondary branch C r And the branch line F connected thereto t The length of the contact from the beginning of the branch line, v is the indication serial number, and k is the minor branch line C r The wire segments are numbered and,ak. bk are the unit length resistance and reactance of the kth section of wire of the secondary branch line, l k The length of the k-th wire of the secondary branch.
The system impedance at any position in the maximum mode and the system impedance in the minimum direction can be obtained by respectively superposing the total resistance and the total reactance of the wire at any position in the corresponding maximum mode and the corresponding minimum mode, for example, the system resistance and the reactance in the maximum mode at a certain position l of the secondary branch line are respectively:
R d (l)＝R d +R C (l)，X d (l)＝X d +X C (l)
in the formula, R d The system resistance and X of a 10kV bus in the maximum mode d The maximum mode is the system reactance at the 10kV bus.
The total impedance here is:
the general impedance formula of the rest parts is similar to the above calculation method, and is not described again.
6. Method for calculating total capacity of distribution transformer in any interval
In the process of hierarchical protection configuration, the total distribution transformer capacity on the distribution line of a certain conductor interval is an important quantity, and based on the distribution line model, the total distribution transformer capacity of any interval can be obtained, and the calculation method is as follows:
(1) The total capacity of the distribution transformation between the trunk line/and the origin is a function of the length l and is expressed as:
in the formula, L DPb Distance, Q, from the distribution position to the beginning of the trunk line Pb To distribute capacity.
(2) The total capacity of the distribution transformation between the branch line/and the start is a function of the length/and is expressed as:
in the formula, L FPb The distance between the distribution position and the beginning of the branch line, Q Pb To distribute capacity.
(3) The total capacity of the distribution transformation between the secondary branch l and the beginning of the secondary branch is a function of the length l and is expressed as:
in the formula, L CPb Is the distance between the distribution position and the beginning of the branch line, Q Pb To distribute capacity.
(4) On the trunk line 1 Is treated with 2 Is prepared from (l) 1 <l 2 ) The total capacity of the distribution transformer is as follows:
Q Z (l 1 ,l 2 )＝Q Z (l 2 )-Q Z (l 1 )
in the formula, L CPb Distance, Q, from the distribution position to the beginning of the trunk line Pb Is the distribution transformation capacity. The branch and sub-branch are similar in their evaluation.
(5) On the main trunk line 2 The total capacity of the distribution transformer between the end and the tail end is:
Q Z (l 2 ,L D )＝Q Z (L D )-Q Z (l 2 )
in the formula, L D Total length of trunk line, L CPb Distance of distribution position from beginning of trunk line, Q Pb To distribute capacity. The branch and sub-branch are similar in their evaluation.
Claims (3)
1. A distribution line model suitable for hierarchical protection configuration is characterized in that the model ignores the differences of types, structures, directions and trends of different distribution lines, and abstracts the distribution lines into four parts, namely 10kV buses, wires, switches and distribution transformers based on the most important characteristics of the distribution lines, namely that any distribution line is connected to the 10kV buses and is composed of the wires, the switches and the distribution transformers; each part is expressed by a specific unified numerical structure to form a unified standard information model, and the impedance at any position and the total distribution and transformation capacity in any interval can be calculated according to the model;
the 10kV bus consists of two numerical structures: system resistance R in (1) maximum mode at 10kV bus d And the system reactance X in the maximum mode d (ii) a (2) System resistance R in minimum mode s And system reactance X in a minimum manner s ；
The lead comprises a main line, branch lines and secondary lines;
the trunk line is characterized in that each wire type is a section according to the type of the wire between the starting end and the tail end, and the number of the sections is determined by the number of times of wire change, the wire type and the length of the main line; if the main trunk lines are connected in series with N types of wires from the beginning end to the end, each type of wire is divided into one section, and the main trunk line is divided into N sections, wherein the ith part, namely the data structure D for the model of the ith section of wire of the main trunk line i Represents:
D i ＝(a i ,b i ,l i )
in the formula, a i The resistance is the unit length resistance of the ith section of lead of the main line, and the unit is Euro/km; b is a mixture of i The unit length reactance of the ith section of the main line is Euro/km; l. the i The unit is km, which is the length of the ith section of the main line; total length of trunk line L D Is the sum of the lengths of all the segmented conductors of the trunk line, i.e.:
the backbone can therefore be represented by data structure D: d = { D = 1 ,D 2 ,…,D N }；
The branch lines are connected with the trunk line, and the number of the branch lines is multiple; thus, a branch line may in some cases have multiple data structures, and each data structure is incremented by an amount of a location, indicating where the branch line connects to the trunk line;
arranged in connection with the main trunkA branch line marked as F t (ii) a The number of the types of the conducting wires which are sequentially connected in series from the beginning end to the end is N f Each type of wire is divided into one segment, and the branch line is divided into N f Data structure F for model of j-th part of section, i.e. j-th section of branch line j Represents: f j ＝(a j ,b j ,l j )；
In the formula, a j The resistance is the unit length resistance of the j section of the wire of the branch line, and the unit is Euro/km; b is a mixture of j The unit length reactance of the j section of the wire of the branch line is Euro/km; l. the j The length of the j section of the conductor of the branch line is km; branch line F t Total length L F The sum of the lengths of all segmented wires of the branch line is as follows:
therefore, the data structure F for the branch line t Represents:
in the formula, L t Is a branch line F t Length from the beginning of the trunk, L, of the trunk contact t Satisfy 0 < L t ＜L D ，L D Total length of trunk line, N f Is a branch line F t The number of the conductor types connected in series from the starting end to the tail end;
the secondary branch is connected with the branch line, and the data structure expressing the secondary branch has one more data relative to the branch line and is used for indicating the branch line connected with the point;
is connected to a branch line F t Primary branch of (D), denoted by C r (ii) a The number of the types of the conducting wires which are sequentially connected in series from the beginning end to the end is N c Each type of wire is divided into one segment, and the branch line is divided into N c A segment; wherein, the data structure C for model of k-th section of wire of branch line k Represents: c k ＝(a k ,b k ,l k )；
In the formula, a k Resistance per unit length of k-th section of wire of secondary branch line, and unit is ohm/km, b k The unit length reactance of the kth section of wire of the secondary branch line is Euro/km; l k The unit of the length of the kth section of lead of the secondary branch is km; secondary branch line C r Total length L C The sum of all segment wire lengths for the secondary branch, i.e.:
thus, the data structure C for the secondary branch r Represents:
wherein t is the serial number of the branch line connected with the secondary branch line, L r Is a secondary branch C r And the branch line F connected thereto t Length of contact from beginning of branch line, L r Satisfy the requirements of
N c Is the minor branch C r The number of the conductor types connected in series from the starting end to the tail end;
the switch comprises a switch position and a switch constant value; the position of the switch is determined by the number of the wire where the switch is located and the distance between the switch and the initial end of the wire; the switch constant value comprises a current constant value and a time constant value of an overcurrent section I, an overcurrent section II and an overcurrent section III; switch available data structure K s Represents;
the switch on the main line is represented as: k is s ＝{D,L DKs ,(I 1 ,t 1 ),(I 2 ,t 2 ),(I 3 ,t 3 )}；
Wherein D is a trunk line number indicating that the switch is located in the trunk line, L DKs Distance of switch position from the beginning of main line, L DKs Satisfy the requirement of
(I 1 ,t 1 )、(I 2 ,t 2 )、(I 3 ,t 3 ) Is divided intoRespectively setting the current and time values of the switch overcurrent I section, the switch overcurrent II section and the switch overcurrent III section;
the switches on the branch line are represented as: k is s ＝{F t ,L FKs ,(I 1 ,t 1 ),(I 2 ,t 2 ),(I 3 ,t 3 )}；
In the formula, F t For branch line reference, it indicates that the switch is located at branch line F t The above step (1); l is FKs Distance between switch position and beginning of branch line, L FKs Satisfy the requirement of
The distance between the switch on the branch line and the starting end of the main line is L FKs +L t ，L t Is a branch line F t A length from a trunk line start end of a trunk line contact point; (I) 1 ,t 1 )、(I 2 ,t 2 )、(I 3 ,t 3 ) Respectively setting the current values and the time values of the switch overcurrent I section, the switch overcurrent II section and the switch overcurrent III section;
the switches on the secondary leg are represented as: k s ＝{C r ,L CKs ,(I 1 ,t 1 ),(I 2 ,t 2 ),(I 3 ,t 3 )}；
In the formula, C r Is a branch line number indicating that the switch is located in the minor branch C r Upper, L CKs Distance of switch position from beginning of minor branch, L CKs Satisfy the requirement of
The switch on the secondary branch is at a distance L from the start of the main line CKs +L r +L t ，L r Is the minor branch C r And the branch line F connected thereto t Length of contact from beginning of branch line, L t Is a branch line F t A length from a trunk line start end of a trunk line contact point; (I) 1 ,t 1 )、(I 2 ,t 2 )、(I 3 ,t 3 ) Respectively setting the current values and the time values of the switch overcurrent I section, the switch overcurrent II section and the switch overcurrent III section;
the distribution transformer comprises a distribution transformer position and a distribution transformer capacity; the distribution transformation position is determined by the number of the lead where the distribution transformation is located and the distance between the distribution transformation position and the initial end of the lead; the distribution capacity is the sum of one or more distribution capacities hooked at a certain position, and the unit is kVA; data structure for distribution transformation P b It is shown that,
the switch on the main line is represented as: p b ＝{D,L DPb ,Q Pb }；
The distribution on the branch line is represented as: p b ＝{F t ,L FPb ,Q Pb }；
In the formula, F t Is a branch line number indicating that the distribution transformer is located on branch line F t Upper, L FPb Is the distance between the distribution position and the beginning of the branch line, L FPb Satisfy the requirement of
The distance between the distribution transformer on the branch line and the starting end of the trunk line is L FPb +L t ，L t Is a branch line F t A length from a trunk line start end of a trunk line contact point; q Pb To a distribution transformation capacity;
the distribution on the secondary branch is represented as: p b ＝{C r ,L CPb ,Q Pb }；
In the formula, C r Is a branch line number indicating that the distribution transformer is located on the secondary branch line C r Upper, L CPb Is the distance between the distribution position and the beginning of the secondary branch line, L CPb Satisfy the requirements of
The distance between the distribution transformer on the secondary branch line and the start end of the main trunk line is L CPb +L r +L t ，L r Is the minor branch C r And the branch line F connected thereto t Length of contact from beginning of branch line, L t Is a branch line F t A length from a trunk line starting end of a trunk line contact point; q Pb Is the distribution transformation capacity.
2. The distribution line model suitable for hierarchical protection configuration according to claim 1, wherein the impedance at any location is the required impedance of the hierarchical protection configuration, and is calculated as follows:
(1) The distance between a certain point on the trunk line and the starting end is l, and the point is positioned on the ith section of the trunk line, namely
The resistance and reactance of the conductor between this point and the start of the trunk are then a function of the length l, expressed respectively as:
in the formula, R Z (l)、X Z (l) Respectively is a resistance function and a reactance function of a main line wire at a position which is l away from the starting end of the main line on the main line; v is an indication serial number; i is the main line conductor segment number; ai. bi is the unit length resistance and reactance of the ith section of the main line lead respectively; l. the i The length of the ith section of lead is the length of the main line;
(2) Branch line F t The distance between the point and the beginning of the branch line is l, and the point is located on the jth section of the branch line, namely
l j For the length of the j-th wire of the branch line, the resistance and reactance of all wires between the point and the beginning of the main line are functions of the length l and are respectively expressed as:
in the formula, R F (l)、X F (l) Respectively a slave master at a distance of l from the starting end of the branch lineThe resistance function and the reactance function of the wire calculated from the starting end of the trunk line; l is t Is a branch line F t A length from a trunk line starting end of a trunk line contact point; v is an indication serial number; j is a branch line F t Conducting wire subsection numbering; aj. bj is the unit length resistance and reactance of the j section of the lead of the branch line respectively; l j The length of the j section of the wire of the branch line;
(3) Minor branch C r The distance between the last point and the beginning of the minor branch is l, and the point is located on the kth section of the branch line, that is
l k The length of the kth section of wire of the branch wire is; the resistance and reactance of all the conductors between this point and the beginning of the trunk are then a function of the length l, expressed respectively as:
in the formula, R C (l)、X C (l) Are each a minor branch C r The resistance function and reactance function of the wire counted from the starting end of the main trunk at the distance of l from the starting end of the secondary branch; l is a radical of an alcohol t Is a branch line F t A length from a trunk line starting end of a trunk line contact point; l is r Is the minor branch C r And the branch line F connected thereto t The length of the contact from the beginning end of the branch line; v is an indication serial number; k is the minor branch C r Conducting wire subsection numbering; ak. bk is the unit length resistance and reactance of the kth section of wire of the secondary branch line respectively; l k The length of the kth section of wire of the secondary branch line;
the system impedance at any position in the maximum mode and the system impedance in the minimum direction are obtained by respectively superposing the total resistance and the total reactance of the lead at any position with the corresponding resistance reactance in the maximum mode and the minimum mode; the system resistance and reactance under the maximum mode of a certain position l of the secondary branch line are respectively as follows:
R d (l)＝R d +R C (l)，X d (l)＝X d +X C (l)
in the formula, R d The system resistance and X of the 10kV bus in the maximum mode d The system reactance is at the position of a 10kV bus in a maximum mode; the total impedance here is:
3. a distribution line model suitable for hierarchical protection configuration according to claim 1, wherein the total distribution transformer capacity of any interval is calculated as follows:
(1) The total capacity of the distribution transformation between the trunk line/and the origin is a function of the length l and is expressed as:
in the formula, L DPb Distance of distribution position from beginning of trunk line, Q Pb To a distribution transformation capacity;
(2) The total capacity of the distribution transformation between the branch line/and the beginning is a function of the length l and is expressed as:
in the formula, L FPb The distance between the distribution position and the beginning of the branch line, Q Pb To a distribution transformation capacity;
(3) The total capacity of the distribution transformation between the secondary branch l and the beginning of the secondary branch is a function of the length l and is expressed as:
in the formula, L CPb The distance between the distribution position and the beginning of the branch line, Q Pb Is the distribution capacity;
(4) On the trunk line 1 Is treated with 2 Is prepared from (l) 1 <l 2 ) The total capacity of the distribution transformer is as follows:
Q Z (l 1 ,l 2 )＝Q Z (l 2 )-Q Z (l 1 )
in the formula, L CPb Distance of distribution position from beginning of trunk line, Q Pb Is the distribution capacity;
(5) On the main trunk line 2 The total capacity of the distribution transformer between the end and the tail end is:
Q Z (l 2 ,L D )＝Q Z (L D )-Q Z (l 2 )
in the formula, L D Total length of trunk line, L CPb Distance of distribution position from beginning of trunk line, Q Pb To distribute capacity.
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