JP2007330010A - Contraction model creation method and contraction model creation system for distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contraction model creation method for distribution system which can contract a distribution system model, in condition that it keeps a certain accuracy in voltage analysis, and a contraction model creation system using this method. <P>SOLUTION: The contraction model creation method for a distribution system which creates a contraction model by contracting a distribution system model composed of a node and a branch divided by this node comprises a system condition setting process S20 which computes the voltage drop of a node by performing circuit computation, based on the distribution system model, a simple contraction process S40 which creates the contraction model by contracting the distribution system model, and a voltage control contraction process S50. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a distribution system reduced model creation method capable of reducing a distribution system model while maintaining a certain voltage analysis accuracy, and a reduced model creation system using the method.

  In order to perform voltage simulation of the distribution system using the tidal current calculation method, it is necessary to create a distribution line model of the target distribution system. Recently, distribution line data (line type, thickness, span length) may be systematized and held as electronic data, and simulation can be performed using this data (see, for example, Patent Document 1). ).

JP 7-308036 A

  However, the power distribution system is composed of a number of switches, line types, loads, branch lines, and the like. In order to hold such information as electronic data, it is necessary to manage each piece of equipment as individual equipment by dividing the information into nodes and branches. Therefore, a maximum of about 500 branch data can be obtained in one distribution system. Therefore, when these data are faithfully reproduced as a system model, a system model composed of a large number of nodes and branches is obtained. This system model is at a level that converges as a tidal current calculation, and the simulation itself can be performed. However, when changing the calculation conditions, a large amount of line data and load data must be individually adjusted. It is not practical. Therefore, it has been a problem to establish a method for reducing the system model while maintaining a certain voltage analysis accuracy.

  The present invention has been made in view of such problems, and a distribution system reduced model creation method capable of reducing a distribution system model while maintaining a certain voltage analysis accuracy, and the method The purpose is to provide a contracted model creation system using.

  In order to solve the above-mentioned problems, a reduced distribution system model creation method according to the present invention creates a reduced model by reducing a distribution system model composed of nodes and branches delimited by the nodes. A step of calculating a voltage drop of a node by performing circuit calculation based on the distribution system model (for example, system condition setting process S20 in the embodiment), and reducing the distribution system model to obtain a reduced model. And a step of creating (for example, a simple reduction process S40 and a voltage management reduction process S50 in the embodiment).

In such a reduced model creation method for a power distribution system according to the present invention, the step of creating a reduced model includes a simple reduction process of consolidating a plurality of consecutive branches without branches into one branch. In the contract processing, aggregation is performed so that the product of the total length of the branches to be aggregated and the total load connected to the branches to be aggregated does not exceed a predetermined value (for example, 10 ⁶ [m · kVA]). Is preferred.

  Further, the method for creating a reduced model of a power distribution system according to the present invention is a step of dividing a power distribution system model into a main line satisfying a predetermined condition and a branch line branched from the main line (for example, the main model in the embodiment). Preferably, the step of creating a contracted model including a line / branch line setting process S30) includes a voltage management contraction process of deleting the branch line while maintaining the voltage analysis accuracy.

  At this time, it is preferable that the voltage management reduction process is configured to delete a branch line whose voltage drop from the main line of the terminal node is less than a predetermined threshold.

  Further, a branch line group consisting of a first branch line including a terminal node where the branch line further branches and the voltage drop from the main line is maximum and a second branch line other than the first branch line is formed. Preferably, the voltage management contraction is configured to delete a second branch line whose voltage drop from the first branch line of the terminal node is less than a predetermined threshold.

  Alternatively, a branch line group consisting of a first branch line including a terminal node where the branch line is further branched and the voltage drop from the main line is maximum and a second branch line other than the first branch line is formed. Preferably, the voltage management contraction is configured to delete the second branch line of the branch line group.

Further, the voltage management reduction process further includes a simple reduction process for aggregating a plurality of consecutive branches having no branches into one branch. In this simple reduction process, the total length of the branches to be aggregated and the aggregation are aggregated. It is preferable to aggregate so that the product of the total of the loads connected to the branches to be executed does not exceed a predetermined value (for example, 10 ⁶ [m · kVA]).

  Further, the contracted model creation system according to the present invention includes an equipment data management means (for example, equipment data file 2 in the embodiment) for managing equipment data of a power distribution system, and reads out equipment data from the equipment data management means and distributes power. Reducing means (for example, the reduction processing unit 3 in the embodiment) for recognizing the system model and generating the reduced model by reducing the distribution system model by the above-mentioned reduced distribution system model generation method. Configured.

  When the reduced model creation method and reduced model creation system of the distribution system according to the present invention are configured as described above, the reduced distribution model is maintained in a state where the voltage analysis accuracy of the distribution system model before reduction is maintained. It can be performed. In particular, in the simple reduction process, the product of the total length of the branch to be reduced and the total load connected to this branch does not exceed a predetermined size. It is possible to prevent the voltage analysis accuracy from being deteriorated. Further, by dividing the distribution system model into main lines and branch lines and deleting branch lines that do not affect the voltage analysis accuracy, effective reduction can be performed.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the configuration of a contracted model creation system 1 for executing the distribution model contracted model creation method according to the present embodiment will be described with reference to FIG. The reduced model creation system 1 includes a facility data file 2 for managing distribution system facility data (line constant, switch, pole transformer tap set value, automatic voltage regulator (SVR), load capacity), The contract processing unit 3 includes a contraction result file 4 and an input / output unit 5 for setting various conditions for the contraction processing unit 3. The reduction processing unit 3 is configured to read the distribution system model represented by the equipment data file 2, create a reduction model while maintaining the voltage analysis accuracy, and store the result in the reduction result file 4. ing.

As shown in FIG. 2, the facility data of such a distribution system includes a branch point, a point where a switch is installed, and a point where the line type of the distribution line changes (this point is referred to as a “node”, hereinafter In the description, a node number i for identifying each is added and expressed as “N _i ”, and a section divided by the node N _i (this section is called “branch”). , With a branch number j for identifying each of them as “B _j ”) as a unit, the impedance information of the distribution line in that section (for example, composed of line type, thickness, and length) Is managed.

Managing equipment data of the distribution system in the facility data file 2, for example, for the node N _i, as shown in FIG. 3 (a), the node number is managed as each one record, the branch B _j, as shown in FIG. As shown in 3 (b), for each branch number, the line type, thickness, length, and load capacity (load facility information) connected in the branch are managed as one record. In addition, as shown in FIG. 3C, the connection information between the node N _i and the branch B _j is managed as one record of the branch number connected for each node number. In this embodiment, it is assumed that all load facility information of the distribution system is managed as attribute information of the branch B _{j. Although} not shown, the distribution facility such as a switch also has the attribute of the branch B _{j in} the same manner. It shall be managed as information. The data management structure shown in FIG. 3 is an example, and the data structure is not limited to this data structure as long as the configuration and attributes of the power distribution system shown in FIG. 2 can be managed.

  Now, a contracted model creation method according to the present invention executed in the contraction processing unit 3 will be described. FIG. 4 shows the overall processing flow in the contraction processing unit 3, and the following description will be made along this flow.

(System information recognition and exception setting processing S10)
When the contraction processing unit 3 is activated, information related to the power distribution system is read from the equipment data file 2 and the target to be contracted is recognized. In addition, in order to avoid excessive deterioration of the facility information due to aggregation and contraction of the distribution system information executed in the subsequent processing, exception setting is performed by the input / output unit 5. Here, the exceptions that can be set are: “Do not aggregate nodes where high-voltage consumers are installed”, “Do not aggregate nodes that serve as boundaries between underground lines and overhead lines”, and “User selected A setting of “no aggregation or reduction of nodes” is possible. By setting so that the nodes where high-voltage consumers are installed are not aggregated, in the subsequent processing, the set nodes are not subject to aggregation / contraction. It is possible to study the installation of phase adjusting devices and to analyze the ferrant effect. At this time, it is possible to configure the specified contract capacity of the high-voltage consumer so that the node where the high-voltage consumer exceeding the specified contract capacity is installed can be excluded from aggregation / contraction. is there. Further, by excluding the node that becomes the boundary between the underground line and the overhead line from the aggregation target, it is possible to avoid an excessive decrease in the facility information (for example, assistance in recognizing facility information). Furthermore, when the user designates a node to be excluded from the aggregation / contraction target, it is possible to examine a new installation of a consumer and a distributed power source using the reduction result.

(System condition setting process S20)
Next, in order to perform subsequent contraction processing, system conditions before contraction are set. Specifically, as shown in FIG. 5, the system analysis processing in the distribution system before contraction is executed to calculate the voltages of all nodes (S21), and the voltage drop for each node is calculated using the result. The calculation process (S22) and the branch passage current (ratio) calculation process (S23) are performed. First, the system analysis process S21 adjusts the load power factor of the high-voltage consumer, and considers the branch loss power so that the system (sending) load power factor of the distribution substation connected to this distribution system becomes the set value. The calculation is repeated. Therefore, as shown in FIG. 6, the system analysis process S21 first has a system (delivery) voltage V _reference [kVrms] as a target value and a system (delivery) load power factor as a target value as the first analysis condition. The PF _reference and the load power factor PF _lc of the low-pressure consumer are set (S200). For example, these values are set as in the following formula (1).

Next, a second analysis conditions, sets a load conversion coefficient K _{P_hc} and low consumer load conversion coefficient K _{W_lc} high pressure consumer (S201). Since the contracted capacity of the load is stored in the equipment data file 2, these load conversion factors K _{P_hc} and K _{W_lc} indicate how much the actual load is relative to the contracted capacity of such a load. The conversion value for showing is set. For example, these values are set as in the following equation (2).

Also, as the third analysis condition, using the equipment data read from the equipment data file 2, the load equipment information P _{hc_e} of the high-voltage consumer is set by the following expressions (3) and (4), and the following expression (5) And the load facility information W _{lc_e} of the low-pressure consumer is set by (6) (S202).

Note that, as described first, in the equipment data file 2 in the present embodiment, all the load information connected to the distribution system is managed as attribute information of the branch B _j (FIG. 7A). reference). Therefore, as shown in FIG. 7B, these pieces of load information are assigned to the nodes N _p and N _p to which this branch B _j is connected, and are set as in the above formulas (3) and (5). The

Furthermore, as the fourth analysis condition, as shown in the equations (7) and (8), the active power component P _hc of the load information of the high voltage consumer, the active power component P _lc of the load information of the low voltage customer, and The reactive power component Q _lc is set, and the active power component P _loss and the reactive power component Q _loss of the branch loss power used in the subsequent calculations are initialized as shown in equation (9) (S203). Here, the load power factor is 100% for low-voltage consumers, that is, only the active power is present and the reactive power is not present. In the following expression, sign (x) is a function that outputs the sign of the argument x. When x ≧ 0, sign (x) = 1, and when x <0, sign (x) = − 1. (The same applies to the following equations).

When the above conditions are set, next, whether or not the value of the active power component P _{hc in} the load information of the high voltage consumer is positive, that is, the high voltage consumer is in the distribution system to be analyzed this time. It is determined whether it is installed (S204). When it is determined that a high-voltage consumer is installed, a circuit calculation (tidal flow calculation) is performed in the subsequent processing, and a process of assigning the system load power factor PF _reference on the sending side to the load power factor of the high-voltage customer is performed. Do.

First, the load power factor PF _hc of the high-pressure consumer is initialized (S205). Specifically, as shown in the following equation (10), the active power component P _hc of the load information of the high-voltage consumer obtained in the above step, the active power component P _lc of the load information of the low-voltage customer, and the branch loss power _Is added to the active power P _loss to calculate the active power P of the system (sending side). Then, as shown in the following equation (11), the system power power that is the target value is invalid from the system active power P thus obtained and the system load power factor PF _reference that is the target value set in step S200. calculating the power amount Q _reference, the reactive power component Q of the load information of the high-pressure consumer from the reactive power component Q _loss of the reactive power component Q _lc and branch power loss of the load information of the grid reactive power component Q _reference and a low-pressure customer Calculate _hc . Then, as shown in the equation (12), the reactive power component Q _hc of the load information of the high voltage consumer obtained in this way and the active power component P _hc of the load information of the high voltage customer set in step S203 are used. The apparent power component W _hc of the load information of the customer is calculated, and the load power factor PF _hc of the high-voltage customer is calculated from these results by Equation (13), and is set as the initial value.

In addition, for the subsequent convergence calculation, an upper limit value PF _{error_limit} [%] of the power factor error and an upper limit value (setting value) of the number of calculations for terminating the calculation when the convergence calculation is divergent or difficult to converge are set. (S206). As the upper limit value PF _{error_limit} of the power factor error, for example, a value such as the following equation (14) is set. Also, a sufficiently large value is initially set for the load power factor error PF _error used in the convergence calculation.

The convergence process of the load power factor error PF _error of the high-pressure consumer is performed using the value set in this way. First, it is determined whether the load power factor error PF _error is equal to or less than the upper limit value PF _{error_limit} of the power factor error that is the set value, or whether the number of calculations is equal to or greater than a predetermined upper limit (S207). System analysis process S21 is complete | finished and it transfers to the next process. On the other hand, when the condition is not satisfied, the load information is updated using various coefficients obtained by the above calculation (S208). Specifically, the following equation (15) by the node N _i high consumer load information (active power component P _{Hc_poqas} and reactive power component Q _{Hc_poqas),} the following equation (16) the node N _i of the low-pressure customer of obtains load information (effective power component P _{Lc_poqas} and reactive power component Q _{Lc_poqas)} respectively, customer nodes load the sum of the two at the node N _i by the following equation (17) (active power component P _Poqas and reactive power component Q _Poqas ).

When the load information of each node is updated to the value of formula (17), line (delivery) circuit calculation (flow calculation) relative to the voltage V _s processing performed (S209), obtains the voltage of all the nodes N _i, this result, strain (feed) current I _s, the voltage drop of all the branches B _j [Delta] V (j), and obtains the passing current I (j) of all the branches B _j. Here, the voltage drop ΔV branch B _j (j), the voltage at the node N _i which is located on the delivery side, shall refer to a voltage dropping at this branch B _j. Note that a generally known method can be applied to the power flow calculation executed in the circuit calculation processing S209, and thus detailed description thereof is omitted.

Next, the system load power after execution of the circuit calculation process S209 is calculated (S210). Specifically, the active power component P _result and the reactive power component Q _result of the system load power are calculated by using the system voltage V _s and the system current I _s calculated in the circuit calculation processing S209 by the following equation (18). Then, the apparent power W _result of the system load is calculated from these values by the following equation (19), and the calculated value PF _result of the system load power factor is calculated. Similarly, as shown in the following equation (20), the branch B _j of the voltage drop [Delta] V (j) and branch B passing current from the I (j) of _j, the branch power loss for each branch active power component P _loss ( j) and reactive power component Q _loss (j) are calculated, and the active power component P _loss and reactive power component Q _loss of the branch loss power are calculated from the sum of the values of all branches.

Next, update processing of the load power factor of the high-pressure consumer is executed (S211). Specifically, using the active power component P _result of the system load power calculated from the result of the circuit calculation, the reactive power component Q _reference of the system (sending) load power as a target value is obtained by the following equation (21). The update value Q _hc ′ of the reactive power in the load information of the high-voltage consumer is calculated by the equation (22), and the reactive power update of the load information of the high-voltage customer is further calculated by the equation (23). The apparent power W _hc of the load information of the high-voltage consumer is obtained from the value Q _hc ′, and the load power factor PF _hc of the high-voltage consumer is calculated and updated.

Then, the convergence condition update process is executed (S212), the power factor error PF _error is calculated by the following equation (24), and the process returns to step S207 until the power factor error PF _error converges or the number of calculation times The above processing is repeated until the value exceeds the set value.

In step S204 described above, when the value of the active power component _{Phc in} the load information of the high voltage consumer is 0 or less, that is, it is determined that no high voltage consumer is installed in the distribution system to be analyzed this time. When the system load power factor PF _reference as the target value cannot be adjusted, the load facility information update (S213) similar to step S208 described above and the circuit calculation process described in step S209 described above are performed. (S214) is executed, the system load power calculation and the branch loss power calculation process similar to those in step S210 are executed (S215), the system analysis process S21 is terminated, and the next process is performed. Move.

Phylogenetic analysis step S21 described above if (see FIG. 5) is completed, it executes the calculation process of the voltage drop [Delta] V (i) for each node N _i (S22). Specifically, as shown in the following equation (25), the determination is made from the system voltage V _s which is the voltage on the sending side calculated in the system analysis process S21 and the respective node voltages V (i). it can.

Also, then, it executes the calculation process of the branches passing current (% of system current I _s of the delivery side) for each branch B _j (S23). The branch passage current I _ration (j) of the branch B _j is calculated by the following equation (26).

(Main line, branch line setting process S30)
By the above process, the voltage drop value ΔV of each node N _i which constitutes the distribution system (i) a branch passing current through the branch B _j (percentage) I _ratio (j) is obtained, then the voltage management, which will be described later For contraction, etc., the distribution system is divided into a main line and a branch line. Specifically, as shown in FIG. 8, the main line setting process S31 and the branch line setting process S38 are included. In the main line setting process S31, an automatic switch is extracted from the facility data, and a section (branch) from the node where the distribution substation is installed (that is, the sending side) to the node where the automatic switch is installed ) Is set to the main line, the SVR is extracted from the equipment data, and the section (branch) from the node on the sending side to the node where the SVR is installed is set to the main line. Among the obtained branch passage current (ratio) I _ratio (j), a high-voltage consumer (for example, a user who has the conditions set in step S10 and step S10 for setting a branch B _j having a predetermined ratio or more as a main line) Process S3 for extracting a high-voltage consumer having a specified contracted capacity or more and setting a section (branch) to a node where the high-voltage consumer is installed as a main line From the process S36 for setting the section to the node that becomes the boundary between the underground line and the overhead line as the main line, and from the process S37 for setting up to the node designated by the user in step S10 (see FIG. 4) Composed.

Further, the branch line setting process S38 sets the branch B _j that has not been set as the main line in the main line setting process S31 described above as a branch line. That is, a series of branch line groups branched from the main line is defined as a branch line group. In this branch line setting process S38, the branch line including the node N in which the total value of the voltage drop from the branch point to the end is the largest in this branch line group is the first branch line. A branch line is defined as a second branch line.

Then, an actual case is shown and the process in the main line / branch line setting process S30 will be described with reference to FIG. The 9 extends from the power distribution substation, shows composed distribution system of 34 nodes N _i. In FIG. 9, the number given on the node indicates the node number of the node N _i , and the branch B _j is not shown, but is connected to nodes connected to both ends (for example, nodes N _p and N _q) . J = p, q, that is, B _{p, q} . In this distribution system, an automatic switch is installed between the nodes N ₅ and N ₆ , a manual switch is installed between the nodes N ₁₂ and N _13, and the nodes N ₂₁ and N ₂₂ are connected. An SVR is installed between the nodes N ₂₈ and N ₂₉ , a high-voltage customer 1 with a capacity of 80 kVA is installed, and a high-voltage customer 2 with a capacity of 40 kVA is installed between the nodes N ₃₁ and N _32. ing. Moreover, the value of% displayed with an arrow on the branch indicates the magnitude of the branch passage current (ratio). Further, in the following description, the branch set to the main line is indicated by a solid line, and the other branch (that is, the branch set to the branch line) is indicated by a dotted line.

First, in the main line setting process S31, a node in which an automatic switch is installed is extracted in step S32. In this case, since the automatic switches are installed in the branches B ₅ and ₆ , as shown in FIG. 10, the section extending from the distribution substation at the node N ₃ and extending to the node N ₆ is set as the main line. Is done. Next, in step S33, the node where the SVR is installed is extracted. In this case, since the SVR is installed in the branches B ₂₁ and ₂₂ , as shown in FIG. 11, a section that branches from the distribution substation at the node N ₁ and extends to the node N ₂₂ is set as the main line. . In step S34, it is assumed that a section where the passing current is a predetermined ratio or more of the sending current (system current), for example, a section where the passing current is 30% or more of the system current is set as the main line. As shown in FIG. 12, the section from the node N ₁₉ to the further branched node N ₂₆ is set as the main line. Further, in step 35, if the main line is set up to the node where the high-voltage consumer of 50 kVA or more is installed, the high-voltage consumer 1 is installed from the node N ₂₆ as shown in FIG. Up to node N ₂₉ is set as the main line. Steps S36 and S37 are not illustrated, but the nodes designated by similar processing are set as the main line.

When the main line is set as described above, the remaining branches are set as branch lines in step S38. That is, as shown in FIG. 14, a section of nodes N _{6 to} N _8, a section of nodes N _{3 to} N _{10 to} N ₁₅ and N _{10 to} N ₁₇ , a section of nodes N _{22 to} N ₂₄ , and a node A section from N _{26 to} N ₃₄ is set as a branch line (branch line group). In the branch line group including the node N ₁₀ , when the voltage drop Vd from the main line at the node N ₁₅ is 2% and the voltage drop Vd from the main line at the node N ₁₇ is 1.5%, the node N ₃ branch lines to N ₁₀ to N ₁₅ is set to the first branch line, the branch line to the node N ₁₀ to N ₁₇ is set to the second branch line. Since the other branch lines are not branched in the branch line group, they are all set as the first branch lines.

(Simple reduction process S40)
When the main line and the branch line are set as described above, in step S40 (see FIG. 4), simple contraction processing is executed for these distribution lines. This simple contraction process S40 performs contraction by a mechanically applicable method without distinguishing between main lines and branch lines. Basically, absolute contractor capacity, distribution line (impedance), etc. Processing that does not change the amount (such processing is called “aggregation”) is performed. Specifically, as shown in FIG. 15, it is composed of a branch aggregation process S41 and a dummy node / dummy branch aggregation process S42.

The branch aggregation process S41 is a process for aggregating sections having nodes that have no branches and only different line types into one branch. For example, as shown in FIG. 16A, a case is considered in which a section composed of _two branches B ₁ and B ₂ connecting nodes N ₁ , N ₂ , and N ₃ is aggregated. In this section, the branch B ₁ is connected to a distribution line having a line type of AL240 and a length of 50 m with a low voltage load of 50 kVA. In branch B ₂ , a low-voltage load of 20 kVA is connected to a distribution line having a line type of AL120 and a length of 100 m. In this case, since the node N ₂ has no branch, as shown in FIG. 16B, the branch B _{1 + 2} connecting the nodes N ₁ and N ₃ , the load L ₁ connected to the note N ₁ , and the node N ₃ The load L ₂ is connected to At this time, the branch B _{1 + 2} has an attribute value that maintains the impedance connecting the branch B ₁ and the branch B _2, and the load is equally divided into the left and right nodes N ₁ and N ₃ . (50 + 20/2 = 35 kVA).

In the branch aggregation process S41, the product of the sum of the branch lengths of the section to be aggregated and the sum of the loads connected to the section is 1000 [m] × 1000 [kVA] (= 10 ⁶ [ m · kVA]) or more, voltage analysis errors using the aggregated distribution system model cannot be ignored. Therefore, in this branch aggregation process S41, aggregation is started from a node close to the sending side, and the product of the sum of the total length and the sum of the loads becomes 1000 [m] × 1000 [kVA] or more. The nodes are aggregated by the above method, and the branch aggregation process S41 is executed again from there. Specifically, as shown in FIG. 17A, when there is a distribution line (a group of branch lines) that is configured by 10 nodes and branches at the node N ₇ , the branch aggregation process S41 is performed. According to this, branches between the nodes N _{1 to} N ₇ can be aggregated. However, for the nodes N _{1 to} N ₅ , the product of the sum of the lengths and the sum of the loads is smaller than 1000 [m] × 1000 [kVA], but exceeds it when the node N ₆ is added. In this case, as shown in FIG. 17B, the branches from the nodes N _{1 to} N ₅ are aggregated, and further the branches from the nodes N _{5 to} N ₇ are aggregated.

  On the other hand, in such a power distribution system, there are cases in which equipment data such as underground equipment (facility) is managed using dummy nodes and dummy branches. Normally, dummy nodes and dummy branches are not set in the equipment data file 2 in terms of distribution line impedance and the like and have no influence on the system analysis, and therefore can be aggregated. For this reason, the dummy node / dummy branch aggregation process S42 is configured to aggregate dummy branches in which impedance information such as line type and span length of branch attribute information is not set and dummy nodes connected thereto. ing. Note that the loads on the dummy branches adjacent to the dummy nodes are aggregated as the loads on the dummy nodes.

Specifically, as shown in FIG. 18A, there are three dummy nodes N _2-1 , N _2-2 and N _2-3 between the node N ₁ and the node N _3, and the node N _If the dummy branch between _2-1 and N _2-2 has a low voltage load of 100 kVA and the low voltage load is not connected to the dummy branch between nodes N _2-2 and N _2-3 , The left and right dummy branches and the dummy nodes N _2-1 and N _2-3 are aggregated, and the dummy branch load (low voltage 100 VA + 0 VA) is connected to the remaining dummy node N _2-2 . In addition, there are a distribution box for supply, an electrical room for supply, a switch for ground, a transformer for ground, and the like as facilities to be aggregated for dummy nodes and dummy branches.

  In addition, considering the influence on the voltage analysis during low voltage conversion, the sections with different taps on the pole transformer are not aggregated. In this simple contraction process S40, the branch (or node) excluded from the contraction target set in the above-described system information recognition and exception setting process S10 (see FIG. 4) is excluded from the aggregation process target. It can also be configured to be excluded. Thereby, the fall of the precision of the excessive equipment information by aggregation can be avoided.

(Voltage management reduction process S50)
In the above simple contraction, there is a limit to the system contraction from the contraction algorithm, and a sufficient contraction effect may not be obtained depending on the system conditions. Therefore, in this embodiment, the voltage management reduction process S50 is executed as a more sophisticated reduction method. In this voltage management contraction, the voltage drop of the branch line is sufficiently small, and further system contraction is performed by omitting a branch line that is not necessarily important for voltage management. As shown in FIG. 19, the voltage management reduction process S50 includes three steps (rule 1 process S51, rule 2 process S52, and rule 3 process S53). Here, the rule 1 process S51 is a process of contracting branch lines that are considered to have a sufficiently small voltage drop and no problem in voltage management. The rule 2 process S52 is a process that leaves the branch line with the largest voltage drop in each branch line group and contracts the other branch lines. Finally, the rule 3 process S53 performs the above-described simple contraction process again on the branch line contracted by the rule 1 and 2 processes.

Hereinafter, the rules 1 to 3 processing S51 to S53 will be described with specific examples. First, as an object of the voltage management reduction process S50, a description will be given using a power distribution system having 42 nodes as shown in FIG. In this FIG. 20, the numbers attached to the top of the node indicates a node number i of the node N _i. In the description, the branch is displayed as B _{p, q} (that is, j = p, q) using the node numbers p, q connected to the left and right. A branch drawn with a solid line indicates a main line, a branch indicated with a dotted line indicates a first branch line, and a branch indicated with a one-dot chain line indicates a second branch line. Further, (arrow extending from, for example, a node N ₂₃₎ arrow extending from the node represents a load connected to the node, the numbers indicating the size of the load. Further, Vd represents a voltage drop [%] from the main line at the node, Vd ′ represents a voltage drop [%] from the first branch line at the node, and in the following description, as necessary, indicate.

The rule 1 process S51 includes a first process in which the voltage drop Vd from the main line to the end node of the branch line is reduced by omitting a branch line having a predetermined ratio, and the first branch line and the second branch. In the branch line group composed of lines, the second branch line is contracted by omitting the second branch line whose voltage drop Vd ′ from the first branch line to the second branch line is less than a predetermined ratio. Process. First, in the first processing, when the threshold is 0.1 [%], the voltage drop Vd from the main line of the node N ₂₄ is 0.05 [%] in FIG. (Nodes N _{13 to} N ₂₄ ) are omitted. Further, the voltage drop Vd of the node N _{22 at} the end of the first branch line extending from the node N ₁₈ to the node N ₂₂ also branches from the node N ₂₀ and branches from the node N ₄₀ and the second branch line extending to the node N _41. Since the voltage drop Vd at the nodes N ₄₁ and N ₄₂ at the end of the second branch line extending to the node N ₄₂ is 0.05% with respect to the main line, this branch line group is also omitted. The As a result, the system configuration of FIG. 21 is obtained. At this time, the load of node N ₂₄ (20 kVA) is connected to node N _13, and the loads of nodes N ₂₂ , N ₄₁ , and N ₄₂ (total 60 kVA) are connected to node N ₁₈ .

Further, in the second process, when the threshold is 0.1 [%], in FIG. 21, among the branch line groups branched from the node N ₁₅ , the voltage drop from the first branch line of the node N ₃₆ . Since Vd ′ is 0.05 [%], the second branch line including this node is omitted. Further, in the branch line group extending from the node N _8, the voltage drop Vd ′ from the first branch line of the nodes N ₃₈ and N ₃₉ is both 0.05 [%]. Two branch lines are also omitted. As a result, the system configuration of FIG. 22 is obtained. At this time, the load of node N ₃₆ (20 kVA) is connected to node N ₃₄ , and the loads of nodes N ₃₈ and N ₃₉ (total 40 kVA) are connected to node N ₁₀ .

The rule 2 process S52 leaves the branch line (that is, the first branch line) including the node having the maximum voltage drop in each branch line group (a series of branch lines group branched from the main line). This is a process of contracting by omitting the branch line (that is, the second branch line). In Figure 22, the branch line groups, the node N ₃ branch line group branched from G1, the branch line groups G2 to branch from the node N _5, and G3, the branch line group that branches from the node N _8, branches from the node N ₁₅ It consists of a branch line group G4. Among these branch line groups, the voltage drop Vd from the main line of the node N _{27 at} the end of the first branch line of the branch group G2 is 0.6 [%], whereas at the end of the second branch line, Since the voltage drop Vd of the nodes N ₂₉ and N ₃₀ is 0.4 [%], it is omitted as the second branch line. The voltage drop Vd from the main line of the node N _{33 at} the end of the first branch line of the branch group G4 is 0.6%, whereas the voltage drop at the node N _{35 at} the end of the second branch line is 0.6%. Since Vd is 0.4 [%], it is omitted as the second branch line. As a result, the system configuration of FIG. 23 is obtained. At this time, the loads (total 40 kVA) of the nodes N ₂₉ and N ₃₀ are connected to the node N _25, and the loads (total 40 kVA) connected to the nodes N ₃₄ and N ₃₅ are connected to the node N ₃₁ .

  The rule 3 process S53 is to re-aggregate the branch sections having no branches and different line types as a result of the above rule 1, 2 processes S51 and S52 by the branch contraction process described in the simple contraction process S40. (Detailed explanation is omitted). In the rule 3 process S53, the product of the sum of the lengths of the branches to be aggregated and the sum of the loads is processed so as to be smaller than 1000 [m] × 1000 [kVA]. At this time, among the loads allocated to the nodes by the above processing, the loads connected to the nodes to be aggregated are equally allocated to the nodes at both ends after aggregation, similarly to the loads connected to the branches. It is.

  As described above, the aggregation performed in the simple contraction process S40 can be contracted without distinction between the main line and the branch line, but the contract does not change the customer contract capacity and the absolute amount of the distribution line (impedance). Therefore, the contraction effect is not so high. On the other hand, the contraction performed in the voltage management contraction process S50 allows a change in the absolute amount of the distribution line (impedance), and therefore has a higher contraction effect than the above-described aggregation (simple contraction). In the rule 1 process S51, priority is given to maintaining the voltage analysis accuracy, and the distribution lines (branch lines) considered to have a small influence in practical voltage management (voltage drop management) are contracted. In the rule 2 process S52, Priority is given to the contraction effect, leaving the distribution line (branch line) with the largest voltage drop, and reducing the other distribution lines (branch line). Therefore, the rule 2 process S52 has a larger reduction effect than the rule 1 process S51.

(Final load determination process S60)
Finally, system analysis is performed on the reduced distribution system, and the final determination of the load is performed. As shown in FIG. 24, the final load determination process S60 performs system analysis for load development, adjusts the customer load power and the high voltage customer load power factor, and considers the branch loss power. Thus, the calculation is repeatedly performed so that the system load power and the power factor become set values. The final load determination process S60 will now be described.

In the system analysis executed in the system condition setting process S20, only the system voltage on the sending side and the system load power factor are used, but here the system load current is also used in the initial setting. First, as a first analysis condition, the user has a system (sending) voltage V _reference [kVrms] as a target value, a system (sending) current I _reference [Arms] as a target value, and a system (sending) as a target value. The load power factor PF _reference and the load power factor PF _lc of the low-pressure consumer are set (S600). For example, these values are set as in the following equation (27). Then, the system (sending) load power W _reference [kVA] as a target value is calculated from these set values by the following equation (28). In the following description, the description of the same variables as those in the above-described system condition setting process S20 will be omitted.

Next, as a second analysis conditions, sets a load conversion coefficient K _{P_hc} and low consumer load conversion coefficient K _{W_lc} high pressure consumer (S601). For example, these values are set as in the following equation (29).

Moreover, using the system data read from the equipment data file 2 as the third analysis condition, the load equipment information P _{hc_e} of the high-voltage consumer is set by the following expressions (30) and (31), and the following expression (32) And, the load facility information W _{lc_e} of the low-pressure customer is set by (33) (S602). As described above, when a node and a branch are omitted by the reduction process, the load connected to the branch or the like is evenly distributed to the nodes connected to both ends of the branch. (P _{hc_e_bn} , W _{lc_e_bn} ) is also used.

Furthermore, as the fourth analysis condition, as shown in the following equations (34) and (35), the active power component P _hc of the load information of the high voltage consumer, the active power component P _lc of the load information of the low voltage customer, and The reactive power component Q _lc is set, and the active power component P _loss and the reactive power component Q _loss of the branch loss power used in the subsequent calculations are initialized as shown in the following equation (36) (S603). .

When the above condition setting is performed, whether or not the system power W _reference as the target value (or the system current I _reference as the target value) is positive, that is, the above-described condition setting is correctly performed. Is determined (S604). System power W _reference as the target value (or, the system current I _reference as the target value) has been determined to be positive, the following equation (37), the initial customer load power factor K _w for apparent power (S605).

Next, it is determined whether or not the value of the active power component P _{hc in} the load information of the high voltage consumer is positive, that is, whether or not the high voltage consumer is installed in the distribution system to be analyzed this time (S606). ). When it is determined that a high-voltage consumer is installed, the circuit calculation (tidal flow calculation) is performed in the same manner as the system condition setting process S20 described above, and the system load power factor PF _reference on the sending side is set to the high-pressure consumer. Performs processing to allocate to load power factor. However, here, the consumer load power W _reference is also subject to convergence calculation.

First, the load power factor PF _hc of the high-pressure consumer is initialized by the following equation (38) (S607). For the subsequent convergence calculation, as shown in the following equation (39), the upper limit value W _{error_limit} [%] of the power error and the upper limit value PF _{error_limit} [%] of the power factor error are set, and the number of calculations Is set (S608). A sufficiently large value is set for the system power error W _error and the system power factor error PF _error used in the convergence calculation.

The convergence process of the power error W _error of the high voltage consumer and the load power factor error PF _error of the high voltage consumer is performed using the values set in this way. First, the power error W _error is less than or equal to the upper limit value W _{error_limit} of the power error that is the set value, and the load power factor error PF _error is less than or equal to the upper limit value PF _{error_limit} of the power factor error that is the set value, or It is determined whether the number of calculations is equal to or greater than a predetermined upper limit (S609). If the condition is satisfied, the final load determination process S60 is terminated. On the other hand, when the condition is not satisfied, the load facility information is updated using various coefficients obtained by the above calculation (S610). Specifically, a high-pressure customer load information of the node N _i by the following equation (40) (active power component P _{Hc_poqas} and reactive power component Q _{Hc_poqas),} the following equation (41) the node N _i of the low-pressure customer of obtains load information (effective power component P _{Lc_poqas} and reactive power component Q _{Lc_poqas)} respectively, customer nodes load the sum of the two at the node N _i by the following equation (42) (active power component P _Poqas and reactive power component Q _Poqas ).

When the load of each node is updated to the value of formula (42), line (delivery) circuit calculated relative to the voltage V _s performed (flow calculation) processing (S611), obtains the voltage of all the nodes N _i, this the results, strain (feed) current I _s, the voltage drop of all the B _j [Delta] V (j), and obtains the passing current I (j) of all the branches B _j. A generally known method can also be applied to the power flow calculation executed in the circuit calculation process S611.

Next, using the system voltage V _s and the system current I _s calculated in the circuit calculation process S611, the apparent power component W _result and the system load power factor PF _{result of the} system load power are obtained by the following equation (43). Further, branch loss powers P _loss and Q _loss are calculated according to the equation (44) (S612).

Next, update processing of the load power coefficient of the consumer is executed (S613). Specifically, the reactive power component Q _hc of the grid load power of the high-voltage consumer is calculated by the following formula (45), and the apparent power component W _result of the grid load power obtained by the formula (43) is used to calculate the following formula: The updated value Kw ′ for the apparent power of the system load power coefficient of the consumer is calculated from (46).

Further, the following equation (47), executes the update processing of the load power factor of the high-pressure consumer (S614), and updates and calculates the load power factor PF _hc of the high-pressure consumer.

Then, by updating the convergence condition, the system power error W _error is calculated using the following formula (48), the power factor error PF _error is calculated using the following formula (49) (S615), and step S609. Returning to FIG. 4, the above processing is repeated until the system power error W _error or the power factor error PF _error converges or the number of calculations exceeds the set value.

In step S606 described above, when the value of the active power component _{Phc in} the load information of the high voltage consumer is 0 or less, that is, it is determined that no high voltage consumer is installed in the distribution system to be analyzed this time. If this happens, the target value PF _reference of the system load power factor cannot be adjusted. Therefore, in such a case, the convergence process of the system power error W _error is executed as shown below.

First, similarly to the above process, it is determined whether the power error W _error is less than or equal to the upper limit value W _{error_limit} of the power error that is the set value, or whether the number of calculations is greater than or equal to a predetermined upper limit (S616). If the condition is satisfied, the final load determination process S60 is terminated. On the other hand, if the condition is not satisfied, the load calculation information update (S617) similar to step S610 and circuit calculation based on the system (sending) voltage V _s similar to step S611 are performed using the above results. (Tidal current calculation) processing (S618) is performed, and the voltages of all the nodes N _i are obtained. From this result, the system (sending) current I _s , the voltage drops ΔV (j) of all the branches B _j , and all the A passing current I (j) of the branch B _j is obtained. Then, the apparent power W _result of the system load power and the branch loss powers P _loss and Q _loss are calculated from the equations (43) and (44) (S619), and the consumers are calculated from the equations (45) and (46). An updated value K _w ′ for the apparent power of the system load power coefficient is calculated (S620). Finally, by updating the convergence condition, the system power error W _error is calculated using the equation (48), and the process returns to step S616 to repeat the above processing until the system power error W _error converges, or the number of calculations Is repeated until exceeds the set value.

If it is determined in step S604 described above that the system power W _reference as the target value (or the system current I _reference as the target value) is not positive, that is, the condition is not set correctly, Updating of the load facility information similar to step S610 (S622), and a circuit calculation process (S623) based on the system (sending) voltage V _s similar to that in step S611, and the system load similar to that in step S612. Power calculation and branch loss power calculation processing are executed (S624), and final load determination processing S60 is terminated.

  As described above, the distribution system reduction model creation method according to the present embodiment is configured to reduce the voltage analysis accuracy while maintaining the voltage analysis accuracy. The effect will be discussed below. First, the voltage analysis result of the distribution system before contracting is V [kVrms], the voltage analysis result of the distribution system after contracting is V ′ [kVrms], and the reference voltage is Vbase (= 6.6 [kVrms]). The voltage analysis accuracy (error) Ve [%] is defined by the following equation (50).

  Table 1 shows the voltage analysis accuracy when the reduction processing according to the present embodiment is performed, and the upper row shows the number of branches before reduction, simple reduction, and voltage management reduction. The middle row shows the voltage analysis accuracy at heavy load, and the lower row shows the voltage analysis accuracy at light load. The sending current is shown in the load conditions in Table 1. The sending power factor was calculated as a 95 [%] delay power factor under heavy load and as a 50 [%] lead power factor under light load. As described above, when the voltage management contraction is executed, the number of branches can be reduced to 30% or less before the contraction, and the voltage analysis accuracy can be less than 0.115%. In management, it is possible to reduce the distribution system while maintaining sufficiently good voltage analysis accuracy.

  In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered. As a first modification, in the above-described embodiment, in the system information recognition and exception setting process S10, the node that is the boundary between the underground line and the overhead line is excluded from the aggregation target, thereby reducing excessive equipment information. Although it is avoided (for example, assistance in recognizing facility information), the position of the nodes constituting the main line in the reduced distribution system model is closer to the actual positional relationship on the map. By making it the structure displayed on, the visibility of the distribution system model after contraction can also be improved.

  As a second modification, in the above-described embodiment, as the distribution system equipment data, a branch point, a point where a switch is set, and a point where the line type of the distribution line changes are used as nodes, and the node is divided by this node. Although the section is managed as a branch, it is also possible to manage a power pole as a node and a wire connecting between the power poles as a branch. In this case, information on load equipment and information on power distribution equipment such as switches are managed as node attribute information.

  As a third modification, in the above embodiment, in the main line setting process S31, an automatic switch is extracted from the equipment data, and this automatic switching is performed from the node where the distribution substation is installed (that is, the sending side). The section (branch) up to the node where the switch is installed is set as the main line, but it is also possible to use a section switch and a connection switch instead of the automatic switch.

As a fourth modification, in the above-described embodiment, in the aggregation processing S41 of the simple reduction branch and the rule 3 processing S53 of the voltage management reduction, an attempt is made to integrate regardless of the line type / thickness of the branch. The product of the sum of the branch lengths of the sections and the sum of the loads connected to the sections is aggregated so as not to exceed 10 ⁶ [m · kVA]. The length (that is, the sum of the impedances of the sections to be aggregated) may be considered.

It is a block diagram which shows the structure of the reduction model creation system which concerns on this invention. It is explanatory drawing which shows the structure of the node and branch in a power distribution system model. It is a data structure figure which shows the management method of equipment data, (a) shows the structure of a node management table, (b) shows the structure of a branch management table, (c) shows the structure of network connection information. It is a flowchart which shows the flow of the whole process of the contraction model creation method which concerns on this invention. It is a flowchart which shows the flow of a system | strain condition setting process. It is a flowchart which shows the flow of a system | strain analysis process. It is explanatory drawing which shows the utilization method of the load connected to the branch in the said system | strain analysis process. It is a flowchart which shows the flow of the setting process of a main track | line and a branch line. It is explanatory drawing which shows the structure of the power distribution system model for demonstrating the setting process of a main line and a branch line. In the said explanatory drawing, it is a figure which shows a state when the area with an automatic switch is set as a main track | line. In the said explanatory drawing, it is a figure which shows a state when a section with SVR is set as a main track | line. In the said explanatory drawing, it is a figure which shows a state when passing electric current sets the area more than a predetermined ratio with respect to sending out current as a main line. In the said explanatory drawing, it is a figure which shows a state when a section with a high voltage consumer who has a predetermined contract capacity is made into a main track. It is a figure which shows the state of the branch line in the said explanatory drawing. It is a flowchart which shows the flow of a simple reduction process. It is explanatory drawing which shows the method of branch aggregation in a simple reduction process, (a) shows before aggregation, (b) shows after aggregation. It is explanatory drawing which shows the restrictions by the product of the span length and capacity | capacitance in branch aggregation, (a) shows before aggregation, (b) shows after aggregation. It is explanatory drawing which shows the method of the dummy node / dummy branch aggregation in a simple reduction process, (a) shows before aggregation, (b) shows after aggregation. It is a flowchart which shows the flow of a voltage management reduction process. It is explanatory drawing which shows the structure of the power distribution system model for demonstrating a voltage management reduction process. In the above explanatory diagram, it is a diagram showing a state when the first processing of the first rule is applied. In the above explanatory diagram, it is a diagram showing a state when the second processing of the first rule is applied. In the above explanatory diagram, it is a diagram showing a state when the second rule is applied. It is a flowchart which shows the flow of the final load determination process.

Explanation of symbols

1 Reduced model creation system 2 Equipment data file (equipment data management means)
3 Reduction processing section (contraction means)
S20 System condition setting process S30 Main line / branch line setting process S40 Simple reduction process S50 Voltage management reduction process

Claims (8)

A method for creating a reduced model of a distribution system that creates a reduced model by reducing a distribution system model composed of nodes and branches separated by the nodes,
Performing a circuit calculation based on the distribution system model to calculate a voltage drop at the node;
Reducing the distribution system model to create the reduced model; and a distribution model reduced model creation method. The step of creating the contracted model includes a simple contracting process that aggregates a plurality of consecutive branches without branches into one branch,
2. The power distribution according to claim 1, wherein in the simple contraction process, the distribution is performed so that a product of a total length of the branches to be aggregated and a total of loads connected to the branches to be aggregated does not exceed a predetermined value. How to create a reduced model of the system. Dividing the power distribution system model into a main line satisfying a predetermined condition and a branch line branched from the main line;
2. The reduced model creation of a distribution system according to claim 1, wherein the step of creating the reduced model includes a voltage management reduction process of deleting the branch line while maintaining voltage analysis accuracy. Method.   4. The distribution system reduced model creation method according to claim 3, wherein the voltage management reduction processing is configured to delete the branch line whose voltage drop from the main line at a terminal node is less than a predetermined threshold. . A branch line group comprising a first branch line including a terminal node at which the branch line is further branched and a voltage drop from the main line is maximum, and a second branch line other than the first branch line. Configure
5. The distribution system according to claim 3, wherein the voltage management reduction process is configured to delete the second branch line whose voltage drop from the first branch line at a terminal node is less than a predetermined threshold. How to create a reduced model. A branch line group comprising a first branch line including a terminal node at which the branch line is further branched and a voltage drop from the main line is maximum, and a second branch line other than the first branch line. Configure
6. The distribution system reduced model creation method according to claim 3, wherein the voltage management reduction process is configured to delete a second branch line of the branch line group. The voltage management reduction process further includes a simple reduction process for aggregating a plurality of branches without branches into one branch,
7. The simple reduction process according to any one of claims 3 to 6, wherein a product of a total length of the branches to be aggregated and a total of loads connected to the branch does not exceed a predetermined value. A reduced model creation method for a power distribution system according to one item. Equipment data management means for managing equipment data of the distribution system;
The equipment data is read from the equipment data management means to recognize a power distribution system model, and the power distribution system model is contracted by the power distribution system contracted model creation method according to any one of claims 1 to 7. A reduced model creating system comprising: a reduced means for creating a reduced model.

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