JP2007215314A - Support system for determining condition when connecting distributed power supply to power distribution network and its program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a condition-determining support system capable of reducing a power distribution loss while stabilizing the quality of power supply, in a network structure in which distributed power supplies are connected to power distribution networks connected dendritically (radially). <P>SOLUTION: This support system is provided with a power-distribution-system structure optimization portion 13, which obtains a structure of power distribution networks which minimizes the power distribution loss, supply hindered power, a voltage imbalance rate, and voltage strain by harmonic waves within permissible ranges simultaneously, as possible structure members by the prescribed number of top members having small distribution losses based on a database 19 in which the information of the power distribution systems and load data and peak load data during a fixed period of time are stored, a possible structure member determination portion 14 which calculates the total loss of each structure member based on the load data and determines a smallest structure as a provisional possible structure, and an optimum transmission voltage determination portion 15 which determines a transmission voltage in such a way that a voltage of the power distribution systems to which the distributed power supplies are connected in the structure of the power distribution networks of the provisional possible members, is suppressed within a permissible range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a support system and a program for determining conditions for connecting a distributed power source to a distribution network.

  A distributed energy source of another power supplier is connected to the existing distribution system (distribution network) of the power company, and the power company generates and supplies each consumer connected to the power distribution system. Electric power is supplied in a state where electric power and electric power injected (reverse power flow) from a distributed energy source are combined. As this distributed energy source, for example, an energy source using natural energy such as solar power generation is increasing due to an energy saving effect, an oil substitution effect, a CO2 reduction effect, and the like.

  Such distributed energy sources using natural energy include, for example, a relatively small one installed on the roof of a detached house and a large one installed in a relatively large building such as an apartment house. Conventionally, injection from a detached house has been performed relatively actively, but in the future, it is expected that the number of grid connections from distributed energy with large size and large output power will increase.

  In general, as shown in FIG. 1, a distribution network formed by a plurality of distribution lines is divided into a plurality of load sections by a switch in order to ensure supply reliability at the time of an accident. Each load section receives supply of electric power from a feeder. And the distribution line of a certain feeder is connected to the distribution lines of other feeders by a normally open interconnection switch. For each feeder of such a power distribution system, a multi-division multi-interconnection system (for example, a 3-division 3-interconnection system or a 6-division 3-interconnection system) operated in a radial (dendritic) configuration is adopted. A distribution network composed of such a radial configuration has existed as an existing facility, and when such a distribution network was constructed, it was assumed that power was supplied from the power company's facilities (power plant / substation). In addition, it is not assumed that the distributed energy source is interconnected in the middle of the above-described distribution network and the injected power flows backward.

  For example, the distribution network can reduce the diameter of the distribution line as it gets farther from the substation, or it can be operated by using various control devices such as sending voltage control by tap switching of the distribution transformer. The quality of consumed power is set within an allowable range. These are currently performed in a state that does not assume injection by the above-described distributed energy source (distributed power source).

  On the other hand, in the case of a distributed power source using natural energy, since it depends on a natural phenomenon, the injected power not only changes from moment to moment, but the power generation amount cannot be controlled. Therefore, especially in the case of large-scale distributed power sources, the amount of fluctuation in the injected power also becomes large, and when the output is large, the influence on the distribution network is very large. May be suppressed.

  Further, since the current power distribution system is configured in a dendritic shape as shown in FIG. 1, it is difficult to say that it is an operation mode capable of dealing with a multi-unit interconnection with a distributed power source expected in the future. For this reason, there are various technical problems such as the possibility of deviating from the allowable voltage range (specified by law) due to the interconnection of multiple distributed power sources, such as during a healthy or accident.

  On the other hand, at present, only one-way fragmented and simple calculation simulations such as only control on the distribution network side and only control on the distributed power source side have been studied.

  The present invention relates to a distributed power supply capable of reducing power distribution loss while stabilizing the quality of power supply in a network configuration in which a distributed power supply is connected to a distribution network connected in a dendritic (radial) manner. It is an object of the present invention to provide a support system and a program for determining a condition for connecting a network to a power distribution network.

  The support system for determining the conditions for linking the distributed power source of the present invention to the distribution network is a storage means for storing distribution system information, load data for a certain period, and peak load data for the certain period A distribution loss and a supply trouble in a state where it is assumed that the distributed energy source is linked to a certain point on the distribution network based on the distribution system information stored in the storage means and the load data in a certain period. A distribution system that seeks the configuration of a distribution network that simultaneously achieves minimization of power, voltage unbalance rate, and harmonic voltage distortion within an allowable range, as a candidate for the upper predetermined number with a small distribution loss. For each configuration candidate determined by the distribution system configuration optimization unit based on the configuration optimization unit and the load data stored in the storage unit, A distributed power source is calculated in a configuration candidate determination unit that calculates a total loss in a fixed period and determines a configuration with the calculated total loss as a temporary candidate, and a distribution network configuration of the temporary candidate determined by the configuration candidate determination unit. And an optimum sending voltage determining unit for determining a sending voltage so that the voltage of the interconnected distribution system falls within an allowable range.

  It is preferable to further include a system configuration determination unit that determines whether or not the power quality standard is satisfied for the temporary candidate pattern determined by the optimum transmission voltage determination unit. Furthermore, the power distribution system configuration optimization unit includes a power distribution system information storage device that stores information on the power distribution system, and a plurality of closed partial feeders that are less than X-linked by the rising unit of the power distribution system represented by a graphics model. Node model information storage device that stores information divided into two parts, and partial feeder creation that searches all the partial feeder configurations that satisfy the radial configuration constraints and satisfy the Y division constraints and the voltage drop constraints in the partial feeders. A loss calculating means for calculating a loss in the partial feeder, a precision calculating means for calculating all candidates satisfying the line capacity constraint at the feeder root by a precise solution, and a candidate satisfying the voltage drop constraint A distribution loss minimum configuration specifying means for specifying one candidate that minimizes the distribution loss as a distribution loss minimum configuration. It is also possible.

  The storage means corresponds to a database. Various types of information stored in the storage means may be physically stored in one storage device or may be stored in different storage devices. In addition, the storage unit and each processing unit may be mounted on the same device (in this case, it becomes a support device as shown in the embodiment), or a part or all of the storage unit may be a processing unit. May be placed in an external database or the like separate from the device on which the is mounted.

  The program of the present invention includes a computer, a power distribution system information stored in storage means in which power distribution system information, load data for a certain period, and peak load data for the certain period are stored, and load data for a certain period. Assuming that the distributed energy source is connected to a desired point on the distribution network based on the above, distribution loss, supply disturbing power, voltage unbalance rate, and harmonic voltage distortion are acceptable. A distribution network configuration optimizing unit that obtains a predetermined number of low distribution loss as a configuration candidate as a configuration candidate, which simultaneously achieves minimization within the distribution network, based on load data stored in the storage means In addition, a total loss is calculated for each configuration candidate determined by the distribution system configuration optimization unit, and the configuration with the smallest total loss is calculated. A configuration candidate determination unit for determining a temporary candidate as a temporary candidate, and a transmission voltage so that the voltage of the distribution system connected to the distributed power source in the temporary candidate distribution network configuration determined by the configuration candidate determination unit falls within an allowable range This is a program for functioning as an optimum transmission voltage determination unit for determining

  The present invention easily finds a distribution system that reduces power distribution loss while stabilizing the quality of power supply in a network configuration in which distributed power sources are connected to a distribution network that is connected in a dendritic (radial) manner. be able to.

  An embodiment of the power distribution system configuration optimization unit of the present invention will be described. FIG. 2 shows the relationship between the distributed power source and the power distribution network. The distribution network 1 is connected to a plurality of substations G1 and G2. The distribution network 1 employs a configuration in which a plurality of distribution lines 2 are connected by a plurality of switches 3 with rising points U1 and U2 connected to the substations G1 and G2 as base points. These switches 3 include a normally open switch (indicated by a white square) and a normally closed switch (indicated by a black square), and the normally open switch functions as an interconnected switch. To do. Thereby, since it is electrically cut | disconnected by the normally open switch shown with the white square, the area from (1) to (3) will receive electric power supply from the substation G1, (4) To (6) receives power supply from the substation G2. In FIG. 2, it is shown as a single line (not branched) for convenience, but in reality, the power distribution network is constructed in a state of branching in a dendritic manner as shown in FIG.

  It is assumed that there is a user (installation applicant) who desires the interconnection of the distributed energy source 5 at a certain point (section (3 in the case of illustration)) with respect to such a power distribution network 1. The distributed energy source 5 includes a distributed power source 5a that generates power using solar power generation or other natural energy, and a storage device 5b (storage battery) that stores electric power generated by the distributed power source 5a. Yes.

  A plurality of taps are provided on the distribution transformers and pole transformers of the distribution substations G1 and G2, and the taps are appropriately set so that the distribution line voltage falls within the allowable range. ing. For example, as shown in FIG. 3, the system from the substation G1 is divided into a plurality of tap sections (in the figure, the first to third tap sections are shown, but there are also later), and the poles The allowable range in each tap section is determined by appropriately setting the taps of the transformer. Normally, pole transformer taps are sometimes located in the city and are difficult to switch easily during operation. On the other hand, as shown in FIG. 4, even when the tap position of the distribution transformer is the same (point A), the voltage at each position is different between a heavy load and a light load. In the case of FIG. 4, when the tap position is set to point A, the distribution line voltage falls within the allowable range in each tap section in the case of heavy load (line a), but in the case of light load, the second tap. The allowable upper limit value is exceeded in the section and the third tap section (line b). Therefore, by switching the tap of the distribution transformer to point B, the distribution line voltage becomes a characteristic as shown by line c in the figure and falls within the allowable range in each tap section. Therefore, in the substation G1, the tap is switched according to the load condition so that the voltage of the distribution system connected to the distributed power source falls within the allowable range. Specific tap determination will be described later.

  The support device according to the present invention is for deriving conditions and countermeasures for reducing the distribution loss of the distribution network while utilizing the reverse power flow from the distributed power source. Such a configuration is adopted.

  FIG. 5 shows an example of the support device 10. The support apparatus 10 can be realized by mounting an application program that realizes the following functions on a computer such as a personal computer. Data necessary for carrying out each processing can be obtained by using data stored in a hard disk or other storage device of a personal computer or by accessing an external database.

  That is, the support device 10 includes an input device 11 such as a keyboard and a mouse, and a display device 12 that displays execution results of various processes. Although not shown, it also has a communication function, and has a function of accessing an external database via the Internet or other communication lines. The internal structure includes a distribution system configuration optimization unit 13, a configuration candidate determination unit 14, an optimum transmission voltage determination unit 15, a system configuration determination unit 16, and a database 19. The distribution system configuration optimization unit 13, the configuration candidate determination unit 14, the optimum transmission voltage determination unit 15, and the system configuration determination unit 16 are operated by a CPU of a personal computer.

  In addition, the personal computer database 19 includes distribution system information (connection status of each wiring, switch installation position, switch status (normally open / normally closed), and substation as shown in FIG. The connection position and various information such as the load of each section) are stored. The load data is associated with date information and stored at arbitrary intervals. For example, representative load data in units of one hour is stored for one year, for example. Furthermore, in this embodiment, three periods of the summer period (June to August), the winter period (December, January, February) and the intermediate period (March to May, September to November) In order to control and manage them separately, peak load data for each period is also recorded.

  In an existing power distribution network, the open / close state of each switch is set without considering the existence of the distributed energy source 5 from the beginning. Therefore, when it is assumed that the distributed energy source 5 is connected to a certain point on the power distribution network 1, a better power distribution network configuration for both (the power distribution network operation manager and the distributed power source installation applicant) May exist. The distribution system configuration optimizing unit 13 obtains this possibility.

  This power distribution system configuration optimizing unit 13 minimizes (1) power distribution loss, (2) power hindering power supply, (3) voltage unbalance rate and (4) harmonic voltage distortion within an allowable range. It has a function to determine the configuration of the distribution network (switch open / closed state) so that the “object” can be achieved simultaneously. Although specific functions will be described later, this allows calculation of a distribution network configuration that reduces distribution loss in consideration of power supply from existing substations and injection power from existing or new distributed energy sources. Can be determined. Here, a configuration candidate group is generated by extracting high-order configuration candidates (for example, 50) having a small distribution loss at the peak load during the designated period (summer, winter, and intermediate period).

The configuration candidate determination unit 14 calculates the total loss during the period based on the following formula for all the configuration candidate groups k that have the minimum loss at the peak load obtained by the distribution system configuration optimization unit 13. The smallest configuration candidate is selected as a temporary candidate.

  The optimum transmission voltage determination unit 15 distributes the distribution of the temporary distribution network configuration determined by the configuration candidate determination unit 14 under the restriction that the voltage of the distribution system connected to the distributed power source is within an allowable range. This determines the 24-hour profile of the transmission voltage that minimizes the weighted sum of the square sum of the voltage fluctuation margin and the tap change count of the distribution transformer installed in the power substation.

  The transmission voltage of each distribution line in the distribution network is discretely controlled by switching the taps of the distribution transformer at the distribution substation, but there are a huge number of combinations of transformer tap position patterns that operate with discrete values. . Of these enormous combinations of tap position patterns, one pattern that minimizes the number of times of switching is provided for the purpose of extending the life of the transformer while keeping the voltage at every point within the allowable range. It is ideal to decide.

  Therefore, the profile of the three-phase voltage at each point is calculated from the passing current data (obtained from the sensor) that can be obtained by multi-point measurement, and all the tap value variation patterns are combined. All tap patterns that can push the voltage within the allowable range are extracted at high speed using a logical function, and among them, the number of tap switching times per day (24 hours) is the smallest and the voltage margin is large Extract candidates.

  The calculation algorithm of such a transmission voltage control function is, for example, “a method for determining an optimum transmission voltage in a distribution system in which distributed power sources are interconnected” (The Journal of Kikai B, Vol. 125, No. 9, 2005, pp. 846). -854: The Institute of Electrical Engineers of Japan: issued on September 1, 2005), and can be realized by applying a known algorithm.

  When the above processing is shown in an image, the calculated transmission voltage profiles of all the distribution lines of the A phase, the B phase, and the C phase are within the allowable voltage range as shown in FIG. If the control is impossible, the temporary candidate to be processed is excluded from the configuration candidate group. The determination of whether or not this control is possible is performed by the optimum delivery voltage determination unit 15. In other words, as described above, the optimum sending voltage determination method executed by the optimum sending voltage determination unit 15 is to determine the forefront condition while originally being within the allowable voltage range within each tap section. Therefore, if the condition is not obtained even by this determination method (it does not fall within the allowable voltage range), an error occurs. Therefore, a process for excluding the error from the configuration candidate group is performed.

  In addition, as shown in FIG. 6B, tap switching is performed by determining an optimum delivery voltage for each hour for one day (24 hours) and selecting a tap for the determined voltage ( The selected tap position is “1”). In the illustrated example, the tap is switched three times within one day. A pattern candidate with the smallest tap switching and a large voltage margin is selected.

  The system configuration determination unit 16 satisfies the power quality standard for a temporary candidate pattern determined by the optimum transmission voltage determination unit 15 and satisfying the above-described conditions (tap switching frequency, voltage margin, etc.) within the allowable voltage range of the system. If it is satisfied, the provisional candidate configuration candidate is determined as the optimal system configuration, and the transmission voltage profile of each distribution line determined by the optimal transmission voltage determination unit 15 for the system configuration is also adopted. To do. On the other hand, the system configuration determination unit 16 excludes system candidates that do not satisfy the power quality standard from the configuration candidate group. The power quality standard is such that the maximum unbalance rate of the node voltage is 3% or less and the maximum distortion rate of the node voltage is 3% or less, but any value can be set.

  FIG. 7 is a flowchart showing the functions of the entire support apparatus according to the above embodiment. First, an input of a time to be controlled is received (S1). Specifically, for example, the “Summer”, “Winter”, and “Intermediate” button areas are displayed on the input screen of the display device, and waiting for any of them to be clicked. To be processed.

  Next, the distribution system configuration optimization unit 13 accesses the database using the accepted period as a key, acquires data during peak load and data such as distribution network configuration during the period, and distribution loss during peak load is reduced. A small upper configuration candidate (for example, 50) is obtained, and a configuration candidate group is generated (S2).

  Next, the configuration candidate determination unit 14 receives each configuration candidate of the configuration candidate group obtained by the distribution system configuration optimization unit 13 and reads load data for the period received in the processing step 1 from the database 19. The total loss is obtained for the configuration candidate k (S3). Then, the configuration candidate determination unit 14 extracts configuration candidates whose calculated total loss is the minimum value, and determines the configuration candidates as temporary candidates (S4).

  The optimum sending voltage determining unit 15 obtains the optimum sending voltage profile in the temporary candidate network system (S5). Then, it is determined whether or not the determined optimum delivery voltage profile falls within the allowable voltage in all sections (controllable) (S6). If it does not fall within the allowable voltage range (No in S6), the current temporary candidate is deleted from the configuration candidate group (S7), and the process returns to processing step S4.

  On the other hand, when it falls within the allowable voltage range (Yes in S6), the process proceeds to processing step 8, and the system configuration determination unit 16 obtains the power quality standard and determines whether the quality standard is satisfied (S8). . If the quality standard is not satisfied, the process returns to the process step S4 via the process step 7, and the process is executed from the determination of the next temporary candidate. If the power quality standard is satisfied, the system configuration of the temporary candidate currently being processed is determined as the optimal system configuration, and the distribution voltage profile of each distribution line obtained by the optimal transmission voltage determination unit 15 is also determined. Adopt.

  By executing the above processing for all the periods, it is possible to obtain an optimum system configuration and the like in each period of one year. Thereby, in each season, it is possible to grasp in advance by simulation that the power loss is the minimum in the load pattern of the season and that the voltage can be properly maintained. Further, in the above processing, the optimum system configuration is obtained one by one in each period, but a plurality may be obtained and the priority order may be determined for each.

Next, the power distribution system configuration optimization unit 13 will be described. In the distribution network configuration, the system configuration changes depending on which switch is used as the interconnection switch, and accordingly, the distribution loss greatly varies. That is, since the loss is proportional to the square of the current, for example, the power loss LA in FIG.
LA = (252 × 0.03) + (152 × 0.02) + (52 × 0.01) = 23.5 [W]
And the power loss LB in FIG.
LB = (102 × 0.03) + (152 × 0.02) + (202 × 0.01) = 11.5 [W]
It becomes. Accordingly, the power loss when the distribution system of FIG. 8B is adopted is smaller than the power loss when the distribution system of FIG. 8A is adopted.

  In the distribution system, it is necessary to determine the combination of opening and closing of a large number of switches so that the distribution loss is minimized. However, in an actual power distribution system, consumers are spread out in a mesh structure with a surface configuration, and the number of switches is usually about 1000 even at the sales office level. For this reason, the total number of system configuration candidates (that is, the total number of combinations of opening and closing switches) is enormous.

  For example, when there are 1000 switches, there are 21000 system configuration candidates, and even if one configuration can be evaluated in 10-30 seconds, it takes about 10293 years as a whole. When the distribution loss is calculated and compared for all combinations of opening and closing of these switches, the calculation time is enormous, which is not realistic.

  Generally, the distribution loss in the actual system is 3 to 4%, but cost reduction of several hundred million yen / year is expected by improving the distribution loss by 1%, for example. However, in the construction of a distribution system, an optimization process that minimizes power loss has not been achieved.

  By the way, in order to reduce power loss in an electric power system, an optimization technique (for example, approximate optimization technique using tabu search, genetic algorithm, simulated annealing, etc.) applying a metaheuristic method has been developed. . The metaheuristics method gives up searching for all combinations of solutions, and based on a certain rule or concept, a solution with an accuracy close to that (approximate optimal solution) can be obtained in a short time.

  However, in this metaheuristics method, the acquisition of the global optimal solution itself is not guaranteed, so it is unclear whether the obtained solution is the optimal solution, and the number of candidate solutions is large. Therefore, there is a problem that it is impossible to verify whether or not the obtained solution is an optimal solution.

  The distribution system configuration optimizing unit 13 efficiently restricts operation using a strict solution method such as ROBDD (Reduced Ordered Binary Decision Diagram) in a power distribution network employing a multi-partition multi-interconnection system such as a three-part / tri-part system. By squeezing candidates that satisfy the requirements, it is possible to determine a strict distribution loss minimum configuration, which can be applied to a distribution network composed of any multi-divided multi-connection system, A description will be given by taking a three-part triple connection as an example.

  As shown in FIG. 9, the distribution system configuration optimization unit 13 includes a distribution system information storage device 21, a node model information storage device 22, a partial feeder creation unit 23, a precision calculation unit 24, and a loss calculation unit 25. The distribution loss minimum configuration specifying means 26 and the operation display means 27 are provided. Note that the node model information storage device 22 can also be mounted in the database 19 shown in FIG.

  The distribution system information storage device 21 stores information on the distribution system. The node model information storage device 22 stores information obtained by dividing the power distribution system represented by the graphics model into a plurality of closed partial feeders that are less than three interconnected by the rising portion.

  Also, the partial feeder creating means 23 can search all partial feeders for a partial feeder configuration that satisfies the radial configuration constraint and satisfies the three-part constraint and the voltage drop constraint within the partial feeder.

  The precision calculation means 24 can calculate all candidates satisfying the feeder line capacity limitation by a precise solution. Moreover, the loss calculation means 25 can calculate the loss in the partial feeder.

  The distribution loss minimum configuration specifying means 26 can specify one candidate having the minimum distribution loss as a distribution loss minimum configuration among candidates satisfying the voltage drop constraint. Note that the function of the loss calculating means 25 may be executed by the distribution loss minimum configuration specifying means 26. The operation display means 27 is a user interface.

  The function of the power distribution system configuration optimization unit 13 will be described with reference to FIG. In FIG. 10, first, distribution system information is extracted from the distribution system information storage device (distribution system information DB) 21 (S110). As will be described later, this information includes system configuration information, line type information, load information, distribution line information, switch information, and the like. Next, the extracted information is converted into a graphics model (S120). Thereby, nodes and sides to be described later are defined.

  Next, the graphics model is divided into partial feeders (S130). That is, the partial feeder creating means 23 creates a partial feeder from the graphics model. As will be described later, one unit is a node (feeder root branch point) and a line connecting the nodes (feeder root branch point).

  Next, a node model is created (S140) and registered in the node model storage means 22 (S150). And the mode which passes restrictions with respect to this node model is extracted (S160). S160 may include a step of searching all the partial feeder configurations that satisfy the radial configuration constraint and satisfy the three-division constraint for each partial feeder.

  Next, a precision solution is applied by the precision calculation means 24 (S170). For example, ROBDD is applied to this precise solution. Finally, the wiring loss is obtained by the loss calculating means 25, and the minimum wiring loss configuration is specified (S180).

《Graphics modeling of distribution system and creation of partial feeder》
FIG. 11 is a graphics model showing a typical example of a power distribution system. In FIG. 11, feeders F1 and F2 are drawn from the distribution substation G1, and feeders F3 and F4 are drawn from the distribution substation G2. A plurality of switches are provided on a distribution line laid out based on rising points U1, U2, U3, U4 (indicated by black circles) of feeders F1, F2, F3, and F4. These switches include normally open switches (indicated by white squares) and normally closed switches (indicated by black squares), and normally open switches function as interconnected switches. . The section load exists in the distribution line between the switches, and in FIG. 11, the section load is indicated by ampere [A].

  When the selection of the interconnection switch is inappropriate, the supply voltage of the distribution system decreases. FIGS. 12A and 12B show the relationship between the supply voltage and feeder capacity (current capacity) of the distribution system of the three-divided three-link system. In FIG. 12A, power from the distribution substation G is supplied to the rising point U (indicated by a black circle) through the feeder F. The distribution line drawn from the rising point U is closed by the interconnection switches A3, A4, A5 during normal operation, the load section closed by the rising point U, the switches A1, A5, the switches A1, A2, 150 [A] is supplied to each of the load section closed by A3 and the load section closed by the switches A2 and A4. In FIG. 12A, these load sections are indicated by dotted circles. The interconnection switch is selected so that the supply voltage at the rising point U (6900 [V] in this embodiment) does not fall below the allowable voltage limit (6600 [V] in this embodiment). There is a need (see FIG. 12B).

《Graphics modeling of system and creation of partial feeder》
As illustrated in FIG. 11, the actual distribution line of the distribution system has a radial configuration with the rising points U1, U2, U3, U4 of the feeders F1, F2, F3, F4 as base points. These radial distribution lines are divided into small areas by normally open switches, and these small areas are interconnected by the switches.

In this example, a graphics model of the distribution system as shown in FIG. 11 is created as follows. First, information on the distribution system is extracted from the distribution system information DB. This distribution system information includes
・ System configuration information (system configuration and information on equipment connection status)
・ Line type information (type of electric wire)
・ Load information (load amount for each section (kW))
・ Distribution line information (rising point, maximum transmission current (annual maximum value of distribution line current), substation feeder number, distribution line rated capacity (allowable current value of distribution line))
-Includes on / off information for switches.

Next, the information on the power distribution system is converted into a graphics model (node model) using nodes. For this conversion, processes (1) to (4) are performed.
(1) The switch and load section are sides with both ends as nodes.
(2) A branch point (a portion where distribution lines intersect) is defined as a node.
(3) Distribution substations and underground lines leading to the rise point are excluded from conversion.
(4) Assign numbers to edges and nodes.

  FIG. 13 shows the result of conversion to the node model. This result is stored in the node model database. In FIG. 13, nodes at connection points in the track section are indicated by white circles, nodes at rising points are indicated by black circles, and nodes at feeder root branch points are indicated by double circles. In addition, the switch is indicated by a thick line with hatching, the load section is indicated by a solid line, and the feeder root load section is indicated by a thick black line. In FIG. 13, the node is indicated by a 2-digit number and the side is indicated by a 3-digit number.

  Next, as shown in FIG. 14, the distribution line connecting the rise and the rise is divided into units (partial feeders PF1 to PF4) so as to satisfy the triple connection.

And as shown in FIG.
(1) Radial configuration constraint (2) Feeder capacity constraint (3) Three-division constraint (4) Among the voltage drop constraints, the search for the interconnection switch is performed so as to satisfy the conditions (1) and (3). In FIG. 15, the search results of the partial feeders PF1, PF2, PF3, and PF4 are indicated by symbols K1, K2, K3, and K4, and the interconnection switches are indicated by blanks.

  In addition, in the search result, the code K4 has an aspect that does not satisfy the three-partition restriction, that is, an aspect in which the divided distribution lines are divided into four or more (including three or more switches). The switch at is excluded from the candidate for the interconnect switch.

  Next, as shown in FIG. 16 and FIG. 17, a search is made for a division mode by the interconnection switch that satisfies (2). FIGS. 16 and 17 show a case where (2) is satisfied when the interconnection switch is selected in a divided manner surrounded by an ellipse. FIGS. 18A and 18B show the calculation results (first and second constraint satisfaction solutions) of the system based on FIGS. 16 and 17. Thereby, the minimum distribution loss configuration is required.

  Next, processing by a precise solution is performed. That is, one solution is selected from each partial feeder, and all combinations of solutions satisfying the feeder capacity constraint of (2) and the 3-part constraint of (3) are used using ROBDD (Reduced Ordered Binary Decision Diagram). To calculate. ROBDD is a graph representing a binary decision graph (BDD) representing a logical function as shown in FIGS. 19A and 19B in a more compact and efficient manner. FIGS. 19A and 19B show an example in which the BDD for obtaining the path from x1 to x3 (logical function f (x1, x2, x3)) is changed to ROBDD.

In the arithmetic constraint equation, the feeder capacity constraint is
S (x11, x12, ..., xij) ≤450
Represented by
Configuration selection constraint (restriction that only one constraint satisfaction configuration can be selected from each partial feeder)
R (x11, x12, ..., xij) = 1
Represented by
The 3 division restriction (restriction that each feeder has less than 3 closed switches) is
F (x11, x12, ..., xij) = 2
(Where xij: 0-1 variable (all solutions satisfying 1 if the jth constraint satisfying solution of partial feeder i is selected is extracted)) is represented in FIG. This is equivalent to finding all routes to the indicated node “1”. In FIG. 20, the logical expression W according to ROBDD of S, R, and F is
W (x11, x12, ..., xij) = 1
W (x1, x2, x3) = x1 + <x2> x3
(<X2> is a conjugate of x2)
It is represented by

Next, a process for specifying the minimum wiring loss configuration is performed. That is, (4) Among the candidates satisfying the voltage drop constraint, the configuration that minimizes the distribution loss is determined as the optimum system configuration. Here, the distribution loss Loss is
Loss = (loss calculated at each partial feeder) + (loss at each feeder root section)
It is represented by

  The loss (including voltage drop) is calculated from the power flow of each feeder, and the configuration that minimizes the distribution loss is determined from the configurations that satisfy the voltage drop constraint of (4). FIG. 21A shows a case where the distribution loss satisfies the voltage drop constraint, and FIG. 21B shows a case where the distribution loss does not satisfy the voltage drop constraint.

A graphics model of a three-division three-way distribution system as shown in FIG.
Number of switches: 140
Number of feeders: 40
System configuration candidates: 2140 = about 1.39 × 1042 When the distribution system configuration optimization unit 13 of this embodiment is applied to determine the minimum distribution loss configuration, the first problem is passed. At that time, the number of candidates is about 4.44 × 1013, and the number of candidates is 32 when the processing by the precision solution is passed, and the number of candidates is 2 when the processing for specifying the minimum wiring loss configuration is passed. Become.

  In this case, the minimum loss was 816.632 [kW], the total system demand was 49.731 MW, and the loss was 1.642%. In other words, since the loss in the actual system is 3-4%, the proposed method improves the loss by about 1.5%, and a cost reduction of 400 million yen can be expected in one year. The calculation time was about 30 minutes using a CPU with an internal clock of 1.7 GHz. In terms of the relationship with the present invention, an optimal distribution network configuration can be obtained in a short time by using a feeder connected to an arbitrary point as a distributed power source.

It is a figure which shows a power distribution network. It is a figure which shows the schematic in the case of connecting a distributed energy source to a power distribution network. It is a figure explaining tap switching. It is a figure explaining tap switching. It is a figure which shows an example of the assistance apparatus which concerns on this invention. It is a figure explaining the operation principle (implementation result of each processing part) of a support device. It is a figure explaining the principle of operation of a support device. It is a figure which shows the example from which a distribution loss changes with the selection modes of a connection switch, (A) is a figure which shows the case where a power loss is large, (B) shows the case where a power loss is small. It is a block diagram which shows one Embodiment of the power distribution system structure optimization part of this invention. It is a flowchart which shows one Embodiment of the power distribution system structure optimization method of this invention. It is a graphics model which shows the typical example of a power distribution system. (A), (B) is a figure which shows the relationship between the supply voltage and feeder capacity | capacitance (current capacity) of the distribution system of a 3 division | segmentation 3 interconnection system. It is a figure which shows the conversion result to a node model. It is a figure which shows a mode that the distribution line which connects a rise and a rise was divided | segmented so that the triple connection might be satisfy | filled per unit. It is a figure which shows the search result when searching for the interconnection switch to satisfy the radial configuration constraint, the three division constraint among the radial configuration constraint, the feeder capacity constraint, the three division constraint, and the voltage drop constraint as operation constraints. is there. It is a figure which shows the result of having searched the division | segmentation aspect by the interconnection switch which satisfy | fills feeder capacity | capacitance restrictions. It is a figure which shows the other result which searched the division | segmentation aspect by the interconnection switch which satisfy | fills feeder capacity restrictions. (A), (B) is a figure which shows the 1st, 2nd constraint satisfaction solution. (A) is a figure which shows the calculation method of BDD, (B) is a figure which shows the calculation method of ROBDD. It is explanatory drawing which shows the calculation method by ROBDD concretely. (A) shows the case where the distribution loss satisfies the voltage drop constraint, and (B) is an explanatory diagram showing the case where the distribution loss does not satisfy the voltage drop constraint. It is a figure which shows the graphics model of a 3 division | segmentation 3 interconnection distribution system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Support apparatus 11 Input apparatus 12 Display apparatus 13 Distribution system structure optimization part 14 Configuration candidate determination part 15 Optimal sending voltage determination part 16 System configuration determination part 19 Database 21 Distribution system information storage apparatus 22 Node model information storage apparatus 23 Partial feeder Preparation means 24 Precision calculation means 25 Loss calculation means 26 Wiring loss minimum configuration specifying means 27 Operation display means

Claims (4)

Storage means for storing distribution system information, load data for a certain period, and peak load data for the certain period,
On the assumption that the distributed energy source is linked to a certain point on the distribution network based on the distribution system information stored in the storage means and the load data in a certain period, distribution loss and supply trouble power , Optimizing the distribution system configuration that seeks the configuration of the distribution network that simultaneously minimizes the voltage imbalance rate and the harmonic voltage distortion within the allowable range as the configuration candidates for the upper predetermined number with small distribution loss And
Based on the load data stored in the storage means, a total loss is calculated for each configuration candidate determined by the distribution system configuration optimization unit, and the configuration with the smallest total loss is determined as a temporary candidate. A configuration candidate determination unit to
An optimum sending voltage determining unit that determines a sending voltage so that the voltage of the distribution system connected to the distributed power source in the temporary candidate distribution network configuration determined by the configuration candidate determining unit is within an allowable range;
A support system that determines the conditions for linking a distributed power supply with a distribution network.   The distribution type power distribution network according to claim 1, further comprising a system configuration determination unit that determines whether or not the power quality standard is satisfied for the temporary candidate pattern determined by the optimum transmission voltage determination unit. A support system that determines the conditions for linking to a network. The power distribution system configuration optimization unit
A power distribution system information storage device storing power distribution system information;
A node model information storage device for storing information obtained by dividing the power distribution system represented by a graphics model into a plurality of closed partial feeders that are less than X-linked by a rising portion;
A partial feeder creating means for retrieving all the partial feeders satisfying a radial configuration constraint and a partial feeder configuration satisfying a Y division constraint and a voltage drop constraint in the partial feeder;
A loss calculating means for calculating a loss in the partial feeder;
A precision calculation means for calculating all candidates that satisfy the feeder capacity constraint at the base of the feeder by a precision solution;
A distribution loss minimum configuration specifying means for specifying one candidate having a minimum distribution loss as a distribution loss minimum configuration among candidates satisfying the voltage drop constraint;
The support system which determines the conditions at the time of connecting the distributed power supply of Claim 1 or 2 to a power distribution network characterized by the above-mentioned. Computer
The distributed energy source is distributed based on the distribution system information stored in the storage means storing the distribution system information, the load data for a certain period, and the peak load data for the certain period, and the load data for the certain period. Simultaneously minimizing power distribution loss, power supply disruption, voltage imbalance rate, and harmonic voltage distortion within an acceptable range, assuming the connection to a desired point on the network A distribution network configuration optimizing unit that obtains a predetermined predetermined number of distribution networks with low distribution loss as a configuration candidate.
Based on the load data stored in the storage means, a total loss is calculated for each configuration candidate determined by the distribution system configuration optimization unit, and the configuration with the smallest total loss is determined as a temporary candidate. Configuration candidate determination unit to perform,
An optimum sending voltage determining unit that determines a sending voltage so that the voltage of the distribution system connected to the distributed power source is within an allowable range in the temporary candidate distribution network configuration determined by the configuration candidate determining unit;
Program to function as.

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