JP2019176586A - Tree-structure power distribution system voltage distribution calculating device, method, and program - Google Patents

Abstract

To enable utilization of the technical assets and program assets of the existing voltage calculating method, and enable handling of different load characteristics including distributed power sources and handling of an SVR, etc., that performs voltage control for voltage management.SOLUTION: Load currents of respective nodes of a tree-structure distribution system are calculated from load characteristic and values voltages given to the respective nodes (S102). Next, the load currents of the nodes are allocated as branch currents of master nodes corresponding to the nodes (S103), and the branch current allocated to the parent node of each of the nodes is sequentially added to the branch current of the parent node in the descending order of the node levels of the nodes (S104). Next, the voltage of each of the nodes is sequentially calculated from the voltage of the master node of the node, the branch node, and a line impedance, in the ascending order of the node levels of the nodes (S105), and whether or not the voltage of each of the nodes is converged is determined (S106). When the voltage of each of the nodes is not converged, the process is repeated. When the voltage of each of the nodes is converged, the voltages of the nodes are outputted as a power distribution system voltage distribution.SELECTED DRAWING: Figure 5

Description

  TECHNICAL FIELD The present invention relates to a tree structure (radial) distribution system voltage distribution calculation apparatus, method and program, and in particular, it can utilize the technical assets and program assets of the current voltage calculation method, and can provide a distributed power source used by consumers. A tree-structured distribution system voltage distribution device capable of handling different load characteristic values, including a voltage regulator such as an SVR (Step Voltage Regulator) that performs voltage control for voltage management, It relates to a method and a program.

  Patent Document 1 describes a power flow calculation device that can be executed in a short time using a tree structure (radial) structure in a power distribution system. This tidal current calculation device calculates outflow active power, reactive power, etc. from the upstream head node to the downstream end node (forward calculation), assuming that there is no outflow power at the end node, the outflow effective from the end to the upstream side By correcting the amount of error between power and reactive power (reverse calculation), the power flow is calculated for a tree-structured distribution system. This method is a method in which electric power is used as a power flow, and is based on the Dist Flow method in which the NR method is developed for a distribution system. The Dist Flow method is described in Non-Patent Document 1.

  Non-Patent Document 1 describes a power flow calculation method for a distribution system using a current as a power flow as the FD2 method. In this method, the voltage is calculated in order from the end by the current from the upper substation and the line impedance by the Newton-Raphson method using the partial differential matrix.

JP-A-8-214458 (Patent No. 3321522)

Hiroyuki Daikichi Hiroyuki Mori: “New Power Flow Calculation in Radial Power Distribution Systems”, Electrical Engineering B, Vol. 126, No. 3, pp 290-296, 2006 Masaru Tanaka, Satoshi Uemura, Hirotake Kobayashi: “Method for Estimating Voltage of Distribution System Based on Sensor Switch Information”, Research Report R04011, pp1-20, October 2005, Central Research Institute of Electric Power Industry

In the current voltage management method described in Non-Patent Document 2, this method uses the transmission voltage and current measured by a switch with sensor function installed in a substation or system, and mainly uses the current. The voltage drop amount due to the line impedance is calculated, and the voltage at each point is calculated by accumulating the voltage drop, and it is assumed that the current flows only in the forward power flow direction. As described in -2, it cannot be applied to reverse power flow in which a distributed power source is introduced.
The power flow calculation device described in Patent Document 1 processes power flow as electric energy, and load characteristic values are also handled as electric energy. Since distributed power sources that have been connected to the distribution lines in recent years are also handled as the amount of power, the power flow is calculated here using the power as the power flow.

In the power flow calculation method of the FD2 method described in Non-Patent Document 1pp292-293, the voltage is calculated in order from the end by the Newton-Raphson method using a partial differential matrix, so the problem that the matrix calculation of convergence becomes complicated is there.

  In terms of operation, if there is a method that can be applied to the reverse power flow utilizing the current voltage calculation method of the distribution system, the technical assets and program assets of the current voltage calculation method can be utilized, which is very effective.

  In addition, the power distribution system is directly connected to consumers, and the load characteristics of the loads used by the consumers differ depending on the type of load, so it is desired to cope with these different load characteristics.

  FIG. 9 shows that load characteristics differ depending on the type of load. As shown in FIG. 9, load characteristics of loads used by consumers who are supplied with electric power by distribution lines include, for example, constant impedance characteristics such as electric heaters, light bulb lighting, and phase advance capacitors, arc lamps, electric There are three types of load characteristics, such as constant current characteristics such as plating equipment, fluorescent lamps, mercury lamps, and constant power characteristics such as induction motors, inverter air conditioners, TVs, and distributed power supplies. It may be necessary to handle the power source as an amount of power or the power source as a current source. That is, it is necessary to handle five characteristics as load characteristic values.

  In addition, at a location where voltage management is performed, such as a node where power flow is calculated and a predetermined section of a distribution line, there are cases where not only one load characteristic but also a plurality of load characteristics among the above five load characteristics. Therefore, it is not sufficient to handle only one load characteristic at one node, and it is desirable to be able to handle the above five different load characteristics at one node.

  In addition, the power flow calculation is performed in consideration of voltage regulators such as SVR (Step Voltage Regulator) that performs voltage control for voltage management, which is a proposition in distribution lines, and storage battery devices that have multiple functions such as charging and discharging. It is desirable to be able to do so.

  The object of the present invention is to solve the above-mentioned problems, to make use of the technical assets and program assets of the current voltage calculation method, different load characteristics including distributed power sources used by consumers, and voltage for voltage management. It is an object of the present invention to provide a tree-structured distribution system voltage distribution apparatus, method, and program capable of handling a voltage regulator such as an SVR (Step Voltage Regulator) that performs control.

  In order to solve the above problems, a tree-structured distribution system voltage distribution calculation apparatus according to the present invention includes a load current calculation means for calculating a load current of each node from a voltage and a load characteristic value given to each node, Allocation means for allocating a load current of a node as a branch current with the parent node of the node, and a branch current allocated to a branch between the parent nodes of the node from nodes in descending order of the node level. Branch current calculation means for sequentially adding to the node, and voltage calculation means for sequentially calculating the voltage of each node from the node in the order of lower node level from the voltage of the parent node of the node, the branch current, and the line impedance given to the branch And a convergence determining means for determining whether or not the voltage at each node has converged, and when it is determined that the voltage at each node has not converged, the voltage calculating means Each calculated voltage is applied to each node, and the process from the load current calculation unit is repeatedly executed. When it is determined that the voltage of each node has converged, each node calculated by the voltage calculation unit is The voltage is output as a distribution system voltage distribution.

  In addition, the tree-structured distribution system voltage distribution calculation apparatus of the present invention further provides a reference voltage given in advance to a root node of a distribution system constituted by a tree structure, a load characteristic value given beforehand to each node, and given to each branch in advance. Input means for inputting the line impedance to be determined and the determination criterion in the convergence determination means, the connection form of the distribution system and the node level of each node, the load characteristic value and line impedance of each node, the initial voltage applied to each node, and the convergence Judgment criteria in the judging means, storage means for storing calculation results and judgments in the respective means and the final calculation results and judgment results, a display unit for displaying the results of the distribution system voltage distribution, and the distribution system voltage distribution A control means for controlling the entire computing device is provided.

  Also, the tree-structured distribution system voltage distribution calculation device of the present invention is such that the load characteristic value given to each node is a constant power characteristic given by a complex power value, a constant impedance characteristic given by a complex impedance value, a complex current A constant current characteristic given by a value, a constant power supply characteristic given by a complex power value as a power supply characteristic, and at least one of five load characteristic values given by a complex current value, or a load characteristic The load current calculation means calculates the load current of the node as a sum of the load currents calculated from the load characteristic values given a plurality of load characteristic values. It is a feature.

  Also, the tree-structured distribution system voltage distribution calculation device of the present invention is characterized in that the convergence determination means has a change width between the voltage of each node calculated by the voltage calculation means and the voltage of each node calculated before that. , The change width of the load current of each node calculated by the load current calculation means and the load current of each node calculated before that, or the branch current of each node calculated by the branch current calculation means and the When the change width with the branch current of each node calculated previously becomes smaller than a predetermined threshold, or the error between the voltage of each node, the load current of each node or the branch current of each node and a predetermined set value When the error becomes smaller than the predetermined threshold or when the error between the load characteristic value calculated from the voltage and load current at the same node as the load characteristic value given in advance becomes smaller than the predetermined threshold, Voltage of de is and judging to have converged.

  Also, in the tree-structured distribution system voltage distribution calculation device according to the present invention, the branch current calculation means sorts the nodes in descending order of level, and calculates the branch currents from the highest level node to the lowest level node. It is characterized by doing.

  In the tree-structured power distribution system voltage distribution calculation device according to the present invention, the voltage calculation means sorts the nodes in order from the lowest level and calculates the voltages in the order from the lowest level node to the higher level node. It is a feature.

  Furthermore, the tree-structured power distribution system voltage distribution calculation device according to the present invention includes a voltage adjustment device including a parent node inserted between a pair of nodes, a child node, and a branch between the parent node and the child node. The voltage adjustment transformation ratio α is set in the pair node, the series impedance inserted in series in the distribution line of the voltage adjustment device is set in the branch instead of the line impedance, and the load is set in the pair node. A parallel impedance inserted between lines of the voltage regulator is set instead of a characteristic value, and the load current calculation means sets the load current of the pair node to zero and sets the load current of the pair node to the parallel The allocation means calculates the load current calculated by the parallel impedance as the branch current of the parent node of the parent node, and the branch current calculation means The branch current of the parent node is calculated from the branch current of the child node and the transformation ratio α by (branch current of the parent node) = α · (branch current of the child node), and the branch of the parent node The current is calculated from the load current and branch current of the parent node by (branch current of parent node) = (load current of parent node) + (branch current of parent node), and the voltage calculating means The voltage of the paired node is calculated from the series impedance, the branch current of the paired parent node, the voltage of the paired parent node, and the transformation ratio α (voltage of the paired node) = α · {(voltage of the paired parent node) − (The series impedance) · (the branch current of the parent node)}.

  The present invention can be realized not only as a tree-structured distribution system voltage distribution calculation device but also as a tree-structured distribution system voltage distribution calculation method and computer program.

  In the power flow calculation of the prior art, power is processed as power flow, and load characteristics and line loss are also handled as power. By making the current less, the load characteristic can be indicated by the current, and the line loss can be separately shown as the increase and decrease of the voltage due to the line impedance and the current. Moreover, the technical and program assets of the current voltage calculation method can be utilized.

  Furthermore, according to the present invention, it is possible to handle different load characteristics including a distributed power source used by consumers, and to have a plurality of functions such as SVR (Step Voltage Regulator) and charging and discharging necessary for voltage management control. Since storage battery devices and the like can be handled as load characteristics, voltage distribution calculation of a tree-structured distribution system can be performed including these. In addition, since devices other than SVR such as a static reactive power compensator (SVC: Static Var Compensator) that controls reactive power are installed between lines of a distribution line, they can be expressed as load characteristics.

  Also, it is not necessary to unify and uniformize different load characteristics such as constant power characteristics, constant current characteristics, and constant impedance characteristics into one load characteristic. The characteristics can be arbitrarily selected, and a plurality of load characteristics can be given to one node, or no load characteristics can be given.

It is a figure which shows roughly the structure of the distribution system of the tree structure which can apply this invention. It is a figure which shows the level of each node (bus | bath) of the distribution system of the tree structure of FIG. It is a block diagram which shows one Embodiment of the distribution system voltage distribution calculation apparatus of the tree structure which concerns on this invention. It is a figure which shows the various values given beforehand with respect to the power distribution system of the tree structure of FIG. It is a flowchart which shows operation | movement of the power distribution system voltage distribution calculation apparatus of the tree structure of FIG. It is a figure which shows the structure of a power distribution system at the time of considering a voltage regulator (SVR). It is a figure which shows the application example of the distribution system voltage distribution calculation method of this invention. It is a figure which shows the comparison result of the distribution system voltage distribution calculation method of this invention, and the general power flow calculation method. It is a figure which shows the different load characteristic by the kind of load.

  First, a tree-structured power distribution system will be described. FIG. 1 is a diagram schematically showing a configuration of a tree-structured distribution system to which the present invention can be applied.

  As shown in FIG. 1, the distribution system with a tree structure has a distribution substation (node) 1 as a starting point as a node (number) 0, and a pole switch and a branch (node) 2 of the distribution line as a node (number). ) 1 to 10, and represented by a tree structure (radial) in which the lines in each section divided by the nodes 1 to 10 are branches 3. In other words, the tree-structured distribution system can be expressed by branches for lines in each section between the nodes, voltages in the sections, and nodes representing the loads in the sections. In FIG. 1, a node number is given for convenience of explanation, but the node number may be arbitrary.

  Here, each element in the tree-structured distribution system is defined as follows. The node that is the most upstream node in the tree-type power distribution system and that exists in one tree is the root node. Further, a node connected by a branch above the node (in the root node direction) is a parent node of the node, and a node connected by a branch below the node is a child node of the node. Also, the number of branches that pass from the root node to the lower node is the level of the node, and a node that does not have a child node is a leaf node. Further, the root node direction from the node is higher, and the leaf node direction from the node is lower.

  In the configuration example of the power distribution system of FIG. 1, node 0 is a root node, and the parent nodes of nodes 1, 2, and 3 connected to root node 0 by branch 3 are root nodes, and nodes 4, 5, 6 Is the node 1, the parent node of the node 7 is the node 2, the parent nodes of the nodes 8 and 9 are the node 5, and the parent node of the node 10 is the node 7. The child nodes of node 1 are nodes 4, 5 and 6, the child node of node 2 is node 7, the child nodes of node 5 are nodes 8 and 9, and the child node of node 7 is node 10. is there.

  Also, since node 1 is connected to root node 0 via only one branch 3, it is a level 1 node, and node 4 is connected to root node 0 via two branches 3. 2 nodes. Nodes 3, 4, 6, 8, 9, and 10 are leaf nodes because they have no child nodes. Since a node is the same as its bus, it will be referred to as a node (bus) below. Further, in the following description, a node (bus) is denoted by reference numeral 1 or 2 as necessary, and a node number is appended with ().

  FIG. 2 is a diagram showing the level of each node (bus) in the tree-structured distribution system of FIG. 2 that are the same as or equivalent to those in FIG. 1 are denoted by the same reference numerals.

  Here, the level of the node (bus) that is the root node (root bus) 1 is 0. Further, since the nodes (buses) 2 (1) to (3) are connected to the root node (root bus) 1 through only one branch 3, their level is 1, and the node (bus) ) 2 (4) to (7) are connected to the root node (root bus line) 1 through the two branches 3, so that their level is 2, and the nodes (bus lines) 2 (8) to (8) ( Since 9) is connected to the root node (root bus line) 1 via three branches 3, their level is 3.

  Based on the above points, the present invention will be described below.

  FIG. 3 is a block diagram showing an embodiment of a tree-structured distribution system voltage distribution calculation apparatus according to the present invention.

  The tree-structured distribution system voltage distribution calculation apparatus of this embodiment includes an input unit 4, a storage unit 5, a calculation / determination unit 6, a display (output) unit 7, and a control unit 8. Note that the calculation / determination unit 6 can be composed of one or more processors. The calculation / determination unit 6 may be configured by hardware or software.

  The input unit 4 is a distribution characteristic representing a connection form of the distribution system, a node level of each node (bus) 2, a voltage (reference voltage) that is a reference at the root node (root bus) 1, and a load of each node (bus) 2 Enter the value, line impedance of each branch, threshold value for convergence determination, etc.

  The storage unit 5 includes a node number storage area corresponding to each node (bus) 2, a branch number storage area corresponding to each branch, and the like, a connection form of the distribution system input from the input unit 13, and each node (bus line). ) 2 node level, root node (root bus) 1 reference voltage (reference voltage), load characteristic value of each node (bus) 2, line impedance of each branch, threshold value for convergence judgment, etc. To do. Further, the storage unit 5 stores intermediate and final calculation results and determination results in the calculation / determination unit 6. Furthermore, the storage unit 5 performs initialization in accordance with an instruction from the control unit 8, and sets the same voltage as the reference voltage at the root node (root bus line) 1 or a voltage of any other value other than the root node (root bus line) 1. Are stored as initial voltage values in the voltage storage area of the node numbers corresponding to all the nodes (buses) 2.

  FIG. 4 is a diagram showing various values given in advance to the tree-structured distribution system of FIG. In FIG. 4, parts that are the same as or equivalent to those in FIG.

  In FIG. 4, a root node (root bus line) 1 of a tree-structured distribution system is a slack (swing) node (bus line), to which a reference voltage is given as a starting point voltage of the distribution line. This reference voltage is a complex number including amplitude information and phase information, but generally, only the amplitude information is given with the phase being zero. The current and voltage calculated below are generally complex numbers including amplitude information and phase information.

  Each node (bus) 2 is a parent node (bus) connected to the child node (bus) 2 at the branch 3 or a leaf node (bus) 2 having no child node (bus) 2, and each of these nodes ( A load characteristic value representing the load is given to the bus 2). Each branch 3 is given line impedance. The load characteristic value of each node (bus) 2 and the line impedance of the branch 3 are stored in the storage unit 5 together with the connection form of the distribution system prior to the voltage distribution calculation of the tree-type distribution system.

  The calculation / determination unit 6 performs calculation and convergence determination of a distribution network voltage distribution having a tree structure according to a flowchart described later.

  Specifically, the calculation / determination unit 6 first inputs the voltage stored in the voltage storage area of the node number corresponding to each node (bus) 2 and the input unit 4 to correspond to each node (bus) 2. The load current of each node (bus) 2 is calculated from the load characteristic value stored in the load characteristic value storage area of the node number, and the calculated load current of the node number corresponding to each node (bus) 2 is calculated. Store in the load current storage area.

  The calculation / determination unit 6 assigns the load current of each node (bus) 2 as a branch current of the branch 3 between the node (bus) and the parent node (bus) of the node (bus), Assigned to the branch 3 between the node (bus) in descending order of the level value stored in the level storage area of each node number and the parent node (bus) of the node (bus) The obtained branch current is added to the branch current stored in the branch current storage area of the parent node number corresponding to the parent node (bus) of the node (bus).

  Further, the calculation / determination unit 6 starts with the node number corresponding to the parent node (bus) corresponding to the parent node (bus) of the node (bus) from the node (bus) having the lowest level value stored in the level storage area of each node number. The voltage stored in the voltage storage area is stored in the branch current storage area of the node (bus) number which is a branch current between the node (bus) and the parent node (bus) of the node (bus). The voltage of the node (bus) is calculated from the branch current stored in the line impedance storage area and the line impedance stored in the line impedance storage area, and the calculated voltage value is stored in the voltage of the node number corresponding to the node (bus). Remember to area.

  The calculation / determination unit 6 performs the above calculation by changing the change width between the voltage stored in the voltage storage area of the node number corresponding to all or a specific node (bus) and the voltage stored before the predetermined threshold value. Execute repeatedly until it becomes smaller, that is, until the voltage converges.

  The display (output) unit 7 displays (outputs) the calculation result in the calculation / determination unit 8. The control unit 8 controls the entire distribution system voltage distribution calculation device having a tree structure.

  FIG. 5 is a flowchart showing an operation of the tree-structured distribution system voltage distribution calculation apparatus of FIG.

  By performing the calculation according to the flowchart of FIG. 5, the voltage distribution of each node (bus) 2 can be calculated, and the branch current of each branch 3 can be calculated.

  In FIG. 5, first, in S101 (voltage initialization), an initial voltage is applied to a node (bus) 2 other than the slack node (bus) 1 to which a reference voltage is applied in advance. This initial voltage may be a reference voltage applied to a slack node (bus), or may be a voltage having any other value. This initial voltage may be a complex number including amplitude information and phase information, but generally provides only amplitude information as described above.

  In the next step S102 (load current calculation), the initial voltage and load at each node (bus) 2 from node (bus) 2 to leaf node (bus) 2 with root node (bus) 1 as the parent node (bus). The load current at each node (bus) 2 is calculated from the characteristic value. The method for calculating the load current will be described in detail later.

  In the next S103 (assignment of load current to branch current), the load current of each node (bus) 2 calculated in S102 is used as the parent node (bus) of the node (bus) 2 and the node (bus) 2. Is assigned as the branch current of branch 3 between

  In the next S104 (branch current calculation), the branch current of each branch 3 is calculated. This branch current is obtained by using the branch current assigned to the branch 3 between the node (bus) 2 and the parent node (bus) of the node (bus) 2 as the node (bus) 2 and the parent node (bus). ) The process of adding to the branch current of the branch 3 between the parent node (bus) of 2 and the node (bus) 2 which is a leaf node (bus) is sequentially executed from the root (bus) 1 to the upper node. Can be calculated.

  In S104 (branch current calculation), calculation is sequentially performed from the leaf node (leaf bus) 2 to the root node (root bus) 1 direction. Thus, although the calculation order is determined in S104 (branch current calculation), the calculation order only needs to satisfy the constraints of the level of the tree structure.

  Here, when the branch current of the branch 3 of the node (bus) connected to the lower level is added to the branch current of the branch 3 of the node (bus) connected to the upper level, the node (bus) 2 of the highest level 3 in FIG. Branch 8 of branch 3 connected to level 2 node (bus) 2 (4), (5), (6), (7) from branch current of branch 3 connected to (8), (9), (10) The current is calculated, and further, the branch current of the branch 3 connected to the level 1 node (bus) 2 (1), (2), (3) is calculated. If the branch currents are calculated by sorting in order, the branch currents can be calculated efficiently using the tree structure effectively.

  In the next S105 (voltage calculation), the voltage of each node (bus) 2 is calculated. The voltage of each node (bus) 2 is determined from the line impedance, the branch current, and the voltage of the parent node (bus) given in advance to the branch 3 between the node (bus) and its parent node (bus). The processing of calculating the voltage of the (bus) is performed by executing from the node (bus) to the leaf node (bus) with the root node (bus) 1 to which the reference voltage is applied as the parent node (bus). be able to.

  In S105 (voltage calculation), calculation is performed in order from the root node (root bus line) to the leaf node (leaf bus line). Thus, although the calculation order is determined in S105 (voltage calculation), the calculation order only needs to satisfy the constraints on the level of the tree structure. Here, the level 1 node (bus) 2 (1), (2), (3), which has a low level, goes to the level 2 node (bus) 2 (4), (5), (6), (7). Further, the calculation is performed from the level 2 node (bus) 2 (4), (5), (6), (7) to the level 3 node (bus) 2 (8), (9), (10). As described above, if the voltages are calculated by sorting the nodes (buses) in descending order of the level, the voltage can be calculated efficiently using the tree structure effectively.

  Next, in S106 (voltage convergence determination), it is determined whether or not the voltage calculated in S105 (voltage calculation) has converged. For example, this can be determined by calculating the change width of the voltage calculated in S105 (voltage calculation) and the previously calculated voltage, and comparing the change width with a threshold value. If the change width is smaller than the threshold value, it is determined that the voltage calculated in S105 (voltage calculation) has converged. If it is determined that the voltage calculated in S105 (voltage calculation) has converged, the calculation result is output and the process is terminated. Otherwise, the calculation is performed in S105 (voltage calculation). The processed voltage is applied to each node (bus), and the processing from S102 is repeated.

  As described above, the voltage distribution of each node (bus) 2 can be calculated, and the branch current of each branch 3 can be calculated. The calculation in S102 (load current calculation) to S105 (voltage calculation) and the determination in S106 (voltage convergence determination) can be executed by the calculation / determination unit 6. Therefore, the calculation / determination unit 6 functions as a load current calculation unit, an allocation unit that allocates the load current to the branch current, a branch current calculation unit, a voltage calculation unit, and a convergence determination unit.

  Next, a method for calculating the load current in S102 (load current calculation) will be described.

  In S102 (load current calculation), the initial voltage given in S101 (voltage initialization) or the voltage of each node (bus) 2 calculated in S105 (voltage calculation) and each node (bus) 2 are given in advance. The load current of each node (bus) 2 is calculated from the obtained load characteristic value.

  The load characteristic values given in advance to each node (bus) 2 are a constant power characteristic value P + jQ given by a complex power value, a constant impedance characteristic value R + jX given by a complex impedance value, and a constant current given by a complex current value. A characteristic value Ir + jIm, a constant power supply characteristic value −P−jQ given as a complex power value as a power supply characteristic, and a constant current power supply characteristic value −Ir−jIm given as a complex current, and a node ( When the voltage of (bus) 2 is V, the load current Il can be calculated by the equation (1).

Here, V ^* represents the conjugate of V. The constant power supply characteristic value and the constant current power supply characteristic value are merely reversed in sign from the constant power characteristic value and the constant current characteristic value.

Formula (1) ...

Il = (P + jQ) / V ^*
Il = V / (R + jX)
Il = Ir + jIm
Il = (− P−jQ) / V ^*
Il = −Ir−jIm

  The load characteristic of the node (bus) 2 may be any one, plural or all of the five load characteristics with respect to one node (bus), or there may be no load characteristic. That is, one node (bus) 2 may have at least one of the five load characteristics or may not have any load characteristics. The load current calculated in S102 (calculation of load current) is the sum of the load currents calculated from the voltage of the node (bus) 2 and the load characteristic value given thereto. Accordingly, the load characteristics and various distributed power sources shown in FIG. 9 can be expressed, and a static reactive power compensator (SVC: Static Var Compensator) that is inserted between lines and controls reactive power is also expressed. can do.

  Although the voltage regulator (SVR) is not considered above, a tree distribution system voltage distribution calculation method when the voltage regulator (SVR) is considered will be described below. This method is basically the same as the method according to FIG. 5, and will be described with reference to FIG.

  FIG. 6 shows the configuration of the power distribution system when considering the voltage regulator (SVR). Here, a configuration of only a branch portion between the nodes (buses) 2 in consideration of the voltage regulator (SVR) 9 is shown.

  The voltage regulator (SVR) 9 is represented by a pair node (bus line) 2a, a pair parent node (bus line) 2b, and a branch 3b between the pair node (bus line) 2a and the pair parent node (bus line) 2b. Is inserted between the nodes (buses) 2 and 2 by the branches 3a and 3c.

  The pair node (bus) 2a has a load characteristic value of zero. Instead, a voltage ratio α for voltage adjustment is set here. The branch 3b is set with a series impedance inserted in series with the distribution line of the voltage regulator (SVR) 9 instead of the line impedance, and the parent node (bus) 2b is adjusted with a voltage instead of a load characteristic value. The parallel impedance inserted between the lines of the device (SVR) 9 is set.

  In this configuration, in S102 (load current calculation), since the load characteristic value of the counter node (bus) 2a is zero, the load current is set to zero. Further, in the parent node (bus line) 2b, the load current is calculated by the parallel impedance set instead of the load characteristic value.

  In S103 (assignment of load current to branch current), the load current calculated by the parallel impedance set in the parent node (bus) 2b is assigned to the branch 3c.

  In S104 (branch current calculation), the current of the branch 3b is calculated from the current of the branch 3a and the transformation ratio α (current of the branch 3b) = α · (current of the branch 3a). The current of the branch 3c is calculated from the load current of the parent node (bus) 2b and the current of the branch 3b (current of the branch 3c) = (load current of the parent node (bus) 2b) + (current of the branch 3b) Calculate with

  In S105 (voltage calculation), the voltage of the pair node (bus) 2a is calculated from the series impedance of the branch 3b, the current of the branch 3b, the voltage of the parent node (bus), and the transformation ratio α (pair node (bus). 2 voltage) = α · {(voltage of parent node (bus) 2) − (series impedance of branch 3b) · (current of branch 3b)}}.

  FIG. 7 shows an application example of the distribution system voltage distribution calculation method of the present invention, FIG. 7A shows a distribution system in this application example, and FIG. 7B shows a node (bus) 2 (3 ), (5), (7), (9) show the set values and calculated values of the load characteristics. Here, although both values are the same, the set value is a load characteristic value set in advance for each node, and the calculated value is a value obtained by repeatedly calculating and converging by this method.

  Here, the node (bus) 2 (3) has a load characteristic with a constant impedance characteristic, the node (bus) 2 (5) has a load characteristic with a constant power characteristic, and the node (bus) 2 (7) is The node (bus) 2 (9) has a load characteristic of a constant power characteristic.

  FIG. 8 shows a comparison result of voltage distributions obtained by the distribution system voltage distribution calculation method of the present invention and a general power flow calculation method. FIGS. 8A and 6B show the voltage of FIG. The case where the regulator (SVR) is not considered and the case where the voltage regulator (SVR) is considered. Here, the node (bus line) 2 (4) is replaced with a voltage regulator (SVR) to be a parent node 2 (before the node 4SVR) and a child node 2 (after the node 4SVR). Note that the general tidal current calculation refers to a tidal current calculation method using the amount of power as a tidal current, and this method includes the method described in Patent Document 1. However, in this general tidal current calculation method, the constant power load Since the load characteristics other than the above cannot be handled, the constant power load is converted here. Here, the voltage is calculated as a phase voltage.

That is, since a load other than a constant power load cannot be calculated in a general power flow calculation, as shown in FIG. 7, the load characteristic converged by the method of the present invention (the calculated value of FIG. 7B) is as shown in FIG. Utilizing the fact that the set value is the same as the setting value of (b), the voltage of each node converged by the method of the present invention is used to divide the load of each node as a constant power load, and this constant power load is retransmitted to each node. After setting (assuming the voltage of each node is unknown), each node voltage was calculated by applying general power flow calculation.
As shown in FIG. 8, each node voltage thus calculated matches the voltage calculated by the method of the present invention. Therefore, the method of the present invention can be used as a constant power load even if various load characteristics are given. It turns out that tidal current calculation is possible as well as giving. The same applies to SVR.
As described above, according to the method of the present invention, it is possible to derive a voltage distribution equivalent to the conventional power flow calculation (having the same value), and to mix load characteristics that cannot be handled by the conventional power flow calculation. Even the voltage distribution can be calculated.

  As mentioned above, although embodiment was described, this invention is not restricted to the said embodiment, What was variously changed is included.

  For example, in the above embodiment, the present invention is realized as a tree-structured distribution system voltage distribution calculation device, but the present invention is a tree-structure that sequentially executes the processing steps in the tree-structure distribution system voltage distribution calculation device. It can be realized as a distribution system voltage distribution calculation method, and can also be realized as a program that causes a computer to function as each means in a tree-structured distribution system voltage distribution calculation apparatus.

  In the operation of FIG. 5 of the above embodiment, S103 (assignment of load current to branch current) is an individual process, but the process of (assignment of load current to branch current) is performed in S102 (load current assignment). Calculation) and can be included in S104 (branch current calculation) processing. In S106 (judgment of voltage convergence), when the voltage change width from the previously calculated voltage becomes smaller than the threshold, it is judged that the voltage of each node (bus) has converged. Then, when the change width of the branch current of each node (bus) and the branch current of each node (bus) calculated before that becomes smaller than a predetermined threshold, or the voltage of each node (bus), When an error between a load current of a node (bus) or a branch current of each node (bus) and a predetermined set value becomes smaller than a predetermined threshold value, it is determined that the voltage of each node (bus) has converged. You can also. Further, when the load characteristic value calculated from the voltage and load current of the same node (bus) as the load characteristic value given in advance is compared and the error becomes smaller than a predetermined threshold value, each node (bus) It can also be determined that the voltage has converged. In these cases, it may be determined that the comparison for all the nodes (buses) is smaller than the threshold value, or it is determined that the comparison for a specific node (busbar) is smaller than the threshold value. You may do it.

1, 2 ... Node (bus)
DESCRIPTION OF SYMBOLS 3 ... Branch 4 ... Input part 5 ... Memory | storage part 6 ... Calculation / determination part 7 ... Display (output) part 8 ... Control part

Claims (9)

A tree-structured distribution system voltage distribution calculation device with current as tidal flow,
Load current calculating means for calculating the load current of each node from the voltage and load characteristic value given to each node;
Allocation means for allocating the load current of each node as a branch current with the parent node of the node;
A branch current calculation means for sequentially adding branch currents assigned to branches between parent nodes of the node from the nodes in order of higher node level to the branch current of the parent node;
Voltage calculation means for sequentially calculating the voltage of each node from the node in order of lower node level from the voltage of the parent node of the node, the branch current, and the line impedance given to the branch;
Convergence determining means for determining whether or not the voltage of each node has converged,
When it is determined that the voltage at each node has not converged, each voltage calculated by the voltage calculation means is given to each node, and the processing from the load current calculation means is repeatedly executed. When it is determined that the voltage has converged, the voltage of each node calculated by the voltage calculation means is output as a distribution system voltage distribution.   Further, an input for inputting a reference voltage given in advance to the root node of the distribution system constituted by a tree structure, a load characteristic value given in advance to each node, a line impedance given in advance to each branch, and a judgment criterion in the convergence judging means Means, distribution system connection form and node level of each node, load characteristic value and line impedance of each node, initial voltage applied to each node, determination criteria in the convergence determination means, calculation and determination in each means A storage means for storing the intermediate and final calculation results and determination results, a display section for displaying the distribution system voltage distribution results, and a control means for controlling the entire distribution system voltage distribution calculation apparatus. The tree-structured distribution system voltage distribution calculation apparatus according to claim 1.   The load characteristic values given to each node are given as complex power values as constant power characteristics given as complex power values, constant impedance characteristics given as complex impedance values, constant current characteristics given as complex current values, and power supply characteristics. The constant current power supply characteristic and the constant current power supply characteristic given by the complex current value are at least one of the five characteristic values or no load characteristic, and the load current calculation means has a plurality of load characteristic values. The tree-structured distribution system voltage distribution according to claim 1 or 2, wherein the load current of a given node is calculated as the sum of the load currents calculated from each load characteristic value. Computing device.   The convergence determination means includes a change width between the voltage of each node calculated by the voltage calculation means and the voltage of each node calculated before that, and the load current of each node calculated by the load current calculation means. The change width of the load current of each node calculated before that, or the change width of the branch current of each node calculated by the branch current calculation means and the branch current of each node calculated before that is predetermined. Or when the error between the voltage of each node, the load current of each node or the branch current of each node and the predetermined set value is smaller than the predetermined threshold, or given in advance The voltage of each node is determined to have converged when an error between the load characteristic value calculated from the voltage and load current of the same node as the load characteristic value becomes smaller than a predetermined threshold value. 1 to the distribution system voltage distribution calculation device tree structure according to any one of the three.   5. The branch current calculation unit according to claim 1, wherein the branch current calculation unit sorts the nodes in descending order of level, and calculates the branch currents in order from the highest level node to the lowest level node. The distribution system voltage distribution calculation device of the tree structure described in 1.   6. The voltage calculation unit according to claim 1, wherein the voltage calculation unit sorts the nodes in order from the lowest level and calculates the voltages in the order from the lowest level node to the higher level node. Tree-structured distribution system voltage distribution calculation device.   The voltage regulator is represented by a parent node inserted between a pair of nodes, a child node, and a branch between the parent node and the child node, and a voltage adjustment transformation ratio α is set in the child node. Then, a series impedance inserted in series in the distribution line of the voltage regulator is set instead of the line impedance in the branch, and is inserted between the lines of the voltage regulator in place of the load characteristic value in the parent node A parallel impedance is set, the load current calculation means sets the load current of the paired node to zero, calculates the load current of the paired parent node with the parallel impedance, and the assigning means sets the parent current of the paired parent node. The load current calculated by the parallel impedance is assigned as a branch current of the node, and the branch current calculation means converts the branch current of the parent node into the branch current of the child node and the transformation ratio α. From (the branch current of the parent node) = α · (the branch current of the child node), the branch current of the parent node is calculated from the load current and the branch current of the parent node (of the parent node). Branch current) = (load current of parent node) + (branch current of parent node), and the voltage calculation means calculates the voltage of the child node as the series impedance and the branch current of the parent node. And the voltage of the parent node and the transformation ratio α, (voltage of the child node) = α · {(voltage of the parent node) − (the series impedance) · (branch current of the parent node)}. The tree-structured power distribution system voltage distribution calculation apparatus according to any one of claims 1 to 6. A tree-structured distribution system voltage distribution calculation method with current as tidal flow,
A first step in which a load current calculation means calculates a load current of each node from a voltage and a load characteristic value given to each node;
A second step in which the assigning means assigns the load current of each node as a branch current of a branch between the parent nodes of the node;
A third step in which the branch current calculation means sequentially adds the branch current assigned between the parent nodes of the node to the branch current between the parent nodes of the parent node from the node in the descending order of the node level;
A fourth step in which the voltage calculation means sequentially calculates the voltage of each node from the node in the order of lower node level, the voltage of the parent node of the node, the branch current, and the line impedance;
The convergence determination means has a fifth step of determining whether or not the voltage of each node has converged;
When it is determined that the voltage of each node has not converged, each voltage calculated in the fourth step is given to each node, and the processing from the first step is repeatedly executed. When it is determined that the voltage has converged, the voltage of each node calculated in the third step is output as a distribution system voltage distribution. A tree-structured distribution system voltage distribution calculation program using current as the tidal flow.
Load current calculation means for calculating the load current of each node from the voltage and load characteristic value given to each node;
Allocation means for allocating the load current of each node as the branch current of the parent node of the node;
A branch current calculation means for sequentially adding branch currents allocated between parent nodes of the node level to branch currents between the parent nodes of the parent node from nodes in descending order of the node level;
Voltage calculation means for sequentially calculating the voltage of each node from the node of the lower node level in order from the voltage of the parent node of the node, the branch current, and the line impedance;
Function as convergence determination means for determining whether or not the voltage of each node has converged,
When it is determined that the voltage at each node has not converged, each voltage calculated by the voltage calculation means is given to each node, and the process from the load current calculation means is repeatedly executed. When it is determined that has converged, a program for outputting the voltage of each node calculated by the voltage calculation means as a distribution system voltage distribution.

Images