JP5592589B1 - Voltage unbalance occurrence cause determination device, voltage unbalance occurrence cause determination method - Google Patents

Abstract

Considering that a plurality of pole transformers connected to any two phases of the three phases of the three-phase distribution lines are equally connected to each of the three phases of the three-phase distribution lines, the three-phase distribution lines The first arithmetic unit that calculates the first degree of influence according to the first voltage unbalance rate and the three phases of the three-phase distribution line are regarded as having the same line impedance, and the second voltage of the three-phase distribution line A second arithmetic unit that calculates a second degree of influence according to the unbalance rate; and a determination unit that determines a cause of occurrence of voltage imbalance in the three-phase distribution line based on the first and second degree of influence. Prepare.

Description

  The present invention relates to a voltage imbalance occurrence cause determination apparatus and a voltage imbalance occurrence cause determination method.

  For example, a three-phase distribution line in which voltage imbalance occurs is known (for example, Patent Document 1).

JP 2012-228045 A

  Generally, when voltage imbalance occurs in a three-phase distribution line including the three-phase distribution line of Patent Document 1, a malfunction of a load connected to the three-phase distribution line may be caused depending on the degree of voltage imbalance. For this reason, it is necessary to grasp the cause of the voltage imbalance in order to eliminate the voltage imbalance, but since there are multiple candidates for the cause of the voltage imbalance, the cause of the voltage imbalance can be analyzed. It becomes complicated and it may be difficult to grasp the cause of the occurrence of voltage imbalance.

The main present invention for solving the above-mentioned problem is that a plurality of pole transformers connected to any two phases of the three phases of the three-phase distribution line are evenly connected to each of the two sets of three phases of the three-phase distribution line. Assuming that the three-phase distribution line has the same line impedance, the first arithmetic unit that calculates the line impedance influence degree according to the first voltage imbalance rate of the three-phase distribution line and the three-phase distribution line have the same line impedance. Based on the second arithmetic unit that calculates the connection phase influence degree of the pole transformer according to the second voltage imbalance rate of the three-phase distribution line, the line impedance influence degree, and the connection phase influence degree A device for determining the cause of voltage imbalance in the three-phase distribution line, and a device for determining the cause of occurrence of voltage imbalance.

  Other features of the present invention will become apparent from the accompanying drawings and the description of this specification.

  According to the present invention, the cause of voltage imbalance can be determined.

It is a figure which shows the power distribution system in embodiment of this invention. It is a front view which shows the mounting column of the horizontal arrangement | sequence in embodiment of this invention. It is a front view which shows the mounting column of the vertical arrangement | sequence in embodiment of this invention. It is a block diagram which shows the hardware of the assistance apparatus in embodiment of this invention. It is a block diagram which shows the assistance apparatus in embodiment of this invention. It is a figure which shows the real system | strain model in embodiment of this invention. It is a figure which shows each voltage imbalance rate in embodiment of this invention. It is a flowchart which shows the flow of the voltage imbalance countermeasure performed using the assistance apparatus in embodiment of this invention.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings.

=== Distribution system ===
Hereinafter, the power distribution system in the present embodiment will be described with reference to FIG. FIG. 1 is a diagram showing a power distribution system in the present embodiment.

  The distribution system 100 is a power system for supplying power from the substation 200 to the loads R1 to R4. The distribution system 100 includes a substation 200, a support device 3 (voltage unbalance occurrence cause determination device), a distribution line L100 (three-phase distribution line), switches LS1 to LS3, pole transformers 61 to 64, and loads R1 to R4. And electric poles 81 to 84.

  Note that although a plurality of switches are provided in the power distribution system 100, for example, three switches are provided for convenience of explanation. A plurality of pole transformers, loads, and utility poles are provided in the power distribution system 100, respectively. For convenience of explanation, for example, four pole transformers are provided.

  The substation 200 is, for example, a distribution substation that steps down the power supplied from the upstream side and supplies the stepped down power to the distribution line L100. The substation 200 has a distribution transformer 101.

  The distribution transformer 101 is a device that transforms, for example, a primary side voltage at a predetermined transformation ratio and outputs the transformed voltage from the secondary side. The distribution transformer 101 is assumed to have a transformation ratio set so that, for example, a voltage of 66 kilovolts is transformed to a voltage of 6.6 kilovolts. The primary side of distribution transformer 101 is connected to one end of transmission line L200. The power transmission line L200 is a power transmission line for supplying a voltage of 66 kilovolts from an upstream primary substation (not shown) to the downstream substation 200, for example. The secondary side of distribution transformer 101 is connected to one end of distribution line L100.

  The distribution line L100 is a power line for supplying power from the substation 200 to the loads R1 to R4, and extends from the upstream substation 200 toward the downstream side. Distribution line L100 is a power line for supplying U-phase, V-phase, and W-phase three-phase AC power from substation 200. The distribution line L100 includes a distribution line L1 that supplies U-phase power, a distribution line L2 that supplies V-phase power, and a distribution line L3 that supplies W-phase power.

  The switches LS1 to LS3 are switches with a measurement function, for example, provided at predetermined positions in the distribution line L100. The switches LS1 to LS3 measure the line current, the line voltage, and the power factor of each phase at the positions where the switches LS1 to LS3 are provided in the distribution line L100, and the measurement signals S1 to S3 indicating the measurement results. Is output.

  The distribution line L100 is divided into a plurality of switch sections by the switches LS1 to LS3. A section between the switches LS1 and LS2 is referred to as a first switch section, and a section between the switches LS2 and LS3 is referred to as a second switch section.

  The pole transformers 61 to 64 are transformers connected to the distribution line L100. The pole transformers 61 to 64 are, for example, transformers that transform the primary side voltage at a predetermined transformation ratio and output the transformed voltage from the secondary side. The pole transformers 61 to 64 are set to have a transformation ratio so that, for example, a voltage of 6.6 kilovolts is transformed to a voltage of 100 volts or 200 volts. Primary sides of the pole transformers 61 to 64 are connected to predetermined positions of the distribution line L100. The primary sides of the pole transformers 61 to 64 are respectively connected to any two-phase (two) distribution lines among the distribution lines L1 to L3. The secondary sides of pole transformers 61 to 64 are connected to loads R1 to R4, respectively. The pole transformers 61 to 64 are respectively connected to positions corresponding to the nodes 71 to 74 in the distribution line L100.

  The loads R1 to R4 are power loads such as lamp loads connected to the distribution line L100. The loads R1 to R4 are connected to the distribution line L100 via pole transformers 61 to 64, respectively. That is, the loads R1 to R4 are connected to any two-phase (two) distribution lines among the distribution lines L1 to L3, respectively, and supplied with power.

  The support device 3 is a device for supporting the cancellation of the voltage imbalance of the distribution line L100.

=== Voltage imbalance ===
Hereinafter, voltage imbalance in the present embodiment will be described with reference to FIG.

<Voltage imbalance and voltage imbalance ratio>
Voltage imbalance means that the amplitude of each phase voltage is different or the phase voltage is out of phase in a three-phase AC voltage in which the phase voltage has the same amplitude and the phase voltage has a phase difference of 120 °. .

  When voltage imbalance occurs in the distribution line L100, the amplitudes of the voltages of the distribution lines L1 to L3 become different from each other, or the phase difference of the voltages of the distribution lines L1 to L3 deviates from 120 °. When a voltage imbalance occurs in the distribution line L100, the loads R1 to R4 are not supplied to the loads R1 to R4, for example, by normally operating the loads R1 to R4 depending on the degree of the voltage imbalance. May cause malfunction. Therefore, voltage unbalance in the distribution line L100 can be reduced by, for example, performing a bridge or changing (renovating) the phase to which the pole transformers 61 to 64 are connected (also referred to as “connection phase”). The voltage imbalance rate indicating the degree needs to be relatively small.

The voltage imbalance rate ε is represented by the ratio of the negative phase voltage to the positive phase voltage, for example, as shown in Equation 1 below. In addition, a normal phase voltage and a negative phase voltage are calculated | required by the symmetrical coordinate method, for example using the phase voltage etc. of the distribution line L100.

<Causes of voltage imbalance>
The voltage imbalance occurs, for example, based on a bias in the connection phase of the pole transformers 61 to 64, a bias in the line impedance of the distribution line L100, and the like.

  When voltage imbalance occurs due to the bias of the connection phase, for example, the voltage imbalance ratio can be reduced by changing the connection phase of the pole transformers 61 to 64.

  The bias of the line impedance of the distribution line L100 is generated, for example, when the horizontal columns 4 (FIG. 2) or the vertical columns 5 (FIG. 3) are provided as the electric poles 81 to 84. When voltage imbalance occurs due to the bias of the line impedance of the distribution line L100, for example, the voltage imbalance ratio can be reduced by performing the stretching on the distribution line L100.

  Therefore, in order to reliably reduce the voltage unbalance rate, it is necessary to determine which of the connection phase bias and the line impedance bias is dominant as a factor that increases the voltage unbalance.

=== Pole ===
Hereinafter, with reference to FIG.2 and FIG.3, the mounting pillar in this embodiment is demonstrated. FIG. 2 is a front view showing horizontally arranged columns in the present embodiment. FIG. 3 is a front view showing vertically arranged columns in the present embodiment.

  Any one of the horizontal arrangement column 4 and the vertical arrangement column 5 is used as the electric poles 81 to 84. For example, in the power poles 81 to 84 of the power distribution system 100, the poles 4 and 5 are mixed.

  The pole 4 has an electric pole main body 40 erected in a substantially vertical direction (Z axis) on the ground, and a brace 41 extending in a substantially horizontal direction (X axis). The brace 41 is provided with distribution lines L1 to L3. The distribution lines L1 to L3 are supported by the arm metal 41 so as to be arranged in the horizontal direction.

  The pole 5 has a utility pole body 50 erected in a substantially vertical direction (Z-axis) on the ground, and supports 51 to 53 for supporting the distribution lines L1 to L3. The distribution lines L1 to L3 are supported by the supports 51 to 53 so as to be arranged in the vertical direction.

  The line impedance of the distribution line L100 may be biased based on the positions of the power poles 81 to 84 in the distribution lines L1 to L3 and which of the poles 4 and 5 are provided as the power poles 81 to 84. As the length of the distribution line L100 increases, the degree of bias of the line impedance may increase. When the line impedance of the distribution line L100 is biased, for example, the two-phase line impedances of the distribution lines L1 to L3 are substantially equal, and the remaining one-phase line impedance is equal to the two-phase line impedance. It will be relatively different. In this case, for example, the line impedances of the distribution lines L1 to L3 may be relatively different from each other.

=== Supporting device ===
Hereinafter, the support apparatus according to the present embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram illustrating hardware of the support device according to the present embodiment. FIG. 5 is a block diagram showing the support device in the present embodiment.

  The support device 3 is a device for supporting the cancellation of the voltage imbalance of the distribution line L100. The support device 3 includes a CPU (Central Processing Unit) 31, a communication device 32, a storage device 33, a display device 34, and an input device 35. The CPU 31 realizes various functions of the support device 3 by executing a program stored in the storage device 33 and controls the support device 3 in an integrated manner. The storage device 33 stores the above-described program and various types of information. The display device 34 is a display that displays information of the support device 3. The input device 35 is, for example, a keyboard or a mouse for inputting information to the support device 3. The communication device 32 communicates with the switches LS1 to LS3 via the network 300.

  The support device 3 further includes a first calculation unit 36 (first calculation unit, second calculation unit, third calculation unit, fourth calculation unit), second calculation unit 37, third calculation unit 38, determination unit 39 ( (Also referred to as “various functions of the support device 3”). The various functions of the support device 3 are realized by the CPU 31 executing a program stored in the storage device 33.

  The first calculation unit 36 determines the first second line impedance influence degree, the second line impedance based on the information shown in the measurement signals S1 to S3, the information stored in the storage device 33, the target coordinate method, and the like. Calculates the degree of influence, the influence level of the first pole transformer connection phase (also referred to as “first connection phase influence degree”), and the degree of influence of the second pole transformer connection phase (also referred to as “second connection phase influence degree”). To do.

  Here, it is assumed that system information of the distribution system 100 is further stored in the storage device 33 by an input from the input device 35. The system information includes, for example, the length of the distribution lines L1 to L3, the positions of the switches LS1 to LS3, the positions of the utility poles 81 to 84, the voltage output from the distribution transformer 101, and the lines of the distribution lines L1 to L3. Information indicating impedance and the like is included. Furthermore, the system information includes information indicating the number of pole transformers for each switch section and the total capacity of the pole transformers for each switch section.

  In the system information, which of the poles 4 and 5 is used as the electric poles 81 to 84, the position of the poles in the distribution line L100, the connection phase of the pole transformers 61 to 64, the pole top Information indicating the respective capacities of the transformers 61 to 64 and the positions of the nodes 71 to 74 is not included. Information not included in the system information is also referred to as constraint information. The constraint information can be acquired by a field survey or the like in the power distribution system 100, but the acquisition work is relatively complicated, and is not included in the system information. The system information includes other information for calculating the voltage imbalance rate of the distribution line L100 in addition to the information described above.

  Based on the calculation result of the first calculation unit 36, the determination unit 39 (determining device) has either a bias of the connection phase or a bias of the line impedance as a factor to increase the voltage imbalance of the distribution line L <b> 100. Determine if there is. The determination unit 39 further determines whether or not the voltage imbalance rate is equal to or less than a predetermined value.

  The 2nd calculating part 37 performs the simulation for reducing the voltage imbalance rate of the distribution line L100 resulting from the bias | inclination of line impedance. Specifically, the 2nd calculating part 37 determines the position etc. which should provide apparatuses, such as a single phase reactor with respect to the distribution line L100, for example, the position where the distribution line L100 should be laid. In addition, the 2nd calculating part 37 determines by the calculation based on the information shown by measurement signal S1 thru | or S3, the information memorize | stored in the memory | storage device 33, an object coordinate method, etc., for example.

  The 3rd calculating part 38 performs the simulation for reducing the voltage imbalance rate of the distribution line L100 resulting from the bias | inclination of a connection phase. Specifically, the 3rd calculating part 38 determines the position etc. which should provide apparatuses, such as the connection phase of pole transformer 61 thru | or 64, the single phase reactor with respect to the distribution line L100, for example. In addition, the 3rd calculating part 38 is determined by the calculation based on the information shown by measurement signal S1 thru | or S3, the information memorize | stored in the memory | storage device 33, an object coordinate method, etc., for example. In addition, about the information memorize | stored in the memory | storage device 33 used by the calculation of the 3rd calculating part 38, suppose that the result of the field survey in the power distribution system 100 is reflected.

=== First Calculation Unit ===
Hereinafter, the first calculation unit in the present embodiment will be described with reference to FIGS. 1, 6, and 7. FIG. 6 is a diagram showing a real system model in the present embodiment. FIG. 7 is a diagram showing each voltage imbalance rate in the present embodiment. In FIG. 7, the voltage imbalance rate at each position of the distribution line L100 under the first to fourth conditions is shown. The first to fourth conditions will be described later.

= Influence level =
As described above, the first calculation unit 36 calculates the first line impedance influence degree, the second line impedance influence degree, the first connection phase influence degree, and the second connection phase influence degree (also referred to as “each influence degree”). To do.

  The 1st and 2nd line impedance influence degree has shown the degree of the influence estimated that the deviation of line impedance gives to the voltage imbalance rate of distribution line L100. The line impedance influence degree is the maximum value of the voltage unbalance rate of the distribution line L100 generated based on the line impedance when the load is balanced. The balanced load means that the total capacities of the pole transformers connected between the lines of the distribution lines L1 to L3 are substantially equal. That is, the pole transformer is equally connected to the distribution lines L1 to L3.

  The 1st and 2nd connection phase influence degree has shown the degree of influence presumed that the bias of a connection phase gives to the voltage imbalance rate of distribution line L100. Each degree of influence is also an index used when determining (determining) which of the connection phase bias and the line impedance bias is dominant as a factor that increases the voltage imbalance of the distribution line L100. . The connection phase influence degree is assumed to be the maximum value of the voltage unbalance rate generated based on the connection phase of the pole transformers 61 to 64 when the line impedance is balanced. The line impedance being balanced indicates that the line impedances of the distribution lines L1 to L3 are substantially equal.

= Calculation of influence of line impedance =
The first calculation unit 36 assumes that the load is balanced, the distribution line L100 is not stretched, and the pole 4 is used as the utility poles 81 to 84 (" The voltage unbalance rate at each position of the distribution line L100 is calculated (solid line in FIG. 7). The first calculation unit 36 sets the maximum value in the voltage unbalance rate (first voltage unbalance rate) under the first condition as the first line impedance influence degree (first influence degree).

  The first calculation unit 36 assumes that the load is balanced, the distribution line L100 is not stretched, and the poles 5 are used as the utility poles 81 to 84 (" (Also referred to as “second condition”), a voltage unbalance rate (first voltage unbalance rate) at each position of the distribution line L100 is calculated (broken line in FIG. 7). The first calculation unit 36 sets the maximum value in the voltage unbalance rate under the second condition as the second line impedance influence degree (first influence degree).

= Connection phase influence =
The first calculation unit 36 calculates the first and second phase influence degrees based on the actual system model, the connection phase arbitrary allocation, the arbitrary allocation under the uniform connection phase total, and the like.

<Arbitrary assignment of connection phase>
The arbitrary connection phase assignment means that the pole transformers 61 to 64 are connected to the two phases of the distribution lines L1 to L3 with the same probability. The connection phase arbitrary assignment is, for example, the probability that the pole transformer 61 is connected to the distribution lines L1 and L2, the probability that the pole transformer 61 is connected to the distribution lines L2 and L3, and the pole transformer 61. Indicates that the probabilities of being connected to the distribution lines L3 and L1 are equal to each other. Under the arbitrary assignment of connection phases, the pole transformers 61 to 64 are connected to any combination of distribution lines under this equivalent probability.

<Arbitrary assignment with the total number of connected phases>
Arbitrary allocation with the total number of connected phases being equal means that the pole transformers 61 to 64 are respectively distributed under the condition that the number of pole transformers connected to the distribution lines L1 to L3 is equal. It is connected to two phases of L1 to L3. The pole transformer connected to each two phases is determined with an equal probability. Under an arbitrary assignment with the total connection phase being equal, the number of pole transformers connected to the distribution lines L1 and L2, the number of pole transformers connected to the distribution lines L2 and L3,
The number of pole transformers connected to the distribution lines L3 and L1 is the same.

<Real system model>
The actual system model is a model for determining the capacity of each pole transformer connected to the distribution line L100 and the position of the node to which the pole transformer is connected for each switch section. In the actual system model, the pole transformers in a predetermined switch section are provided at equal intervals, and the capacities of the pole transformers are equal. The capacity of each pole transformer is equal to the total capacity of the pole transformers provided in the given switch section by the number of pole transformers provided in the given switch section. Capacity.

  For example, three pole transformers 61 to 63 are provided in the first switch section in the distribution system 100 (FIG. 1). When the real system model is applied to the first switch section, three pole transformers 611 to 631 having the same capacity are provided in the first switch section. The pole transformers 611 to 631 are provided at equal intervals D1. The capacities of the pole transformers 611 to 631 are the capacities obtained by dividing the total capacity of the pole transformers 61 to 63 into three equal parts.

  The first calculation unit 36 assumes that the line impedance is balanced, the power distribution system 100 corresponds to the real system model, and performs the arbitrary assignment of the connection phases (also referred to as “third condition”). Calculate the influence of one connected phase.

  Specifically, the first calculation unit 36 calculates the voltage imbalance rate at each position of the distribution line L100 a plurality of times under the third condition, and calculates the average value at each position of the calculation result for each position of the distribution line L100. Is calculated as a voltage unbalance rate (second voltage unbalance rate) in FIG. Thereafter, the first calculation unit 36 sets the maximum value in the voltage unbalance rate under the third condition as the first connection phase influence degree (second influence degree). That is, the 1st calculating part 36 makes the maximum value in the average value of the voltage imbalance rate of each position for several times the 1st connection phase influence degree.

  The first calculation unit 36 performs the arbitrary allocation under the condition that the line impedance is balanced, the power distribution system 100 corresponds to the real system model, and the total of the connected phases is equal (“fourth condition” The second connection phase influence degree is calculated.

  Specifically, the 1st calculating part 36 calculates the voltage imbalance rate in each position of the distribution line L100 several times on 4th conditions, and calculates the average value in each position of the said calculation result in each position of the distribution line L100. Is calculated as a voltage unbalance rate (second voltage unbalance rate) at (a two-dot chain line in FIG. 7). Thereafter, the first calculation unit 36 sets the maximum value in the voltage unbalance rate under the fourth condition as the second connection phase influence degree (second influence degree). That is, the 1st calculating part 36 makes the maximum value in the average value of the voltage imbalance rate of each position for several times the 2nd connection phase influence degree.

=== Determining Unit ===
Hereinafter, the determination unit in the present embodiment will be described with reference to FIGS. 5 and 7.

  Based on each degree of influence, the determination unit 39 determines which of the connection phase bias and the line impedance bias is dominant as a factor that increases the voltage imbalance of the distribution line L100.

  The determination unit 39 determines which of the connection phase bias and the line impedance bias is dominant based on the magnitude relationship between the influence levels. For example, when both the first and second line impedance influence degrees are larger than both the first and second connection apparatus influence degrees, the determination unit 39 increases the voltage imbalance of the distribution line L100 due to the deviation of the line impedance. Judgment (determination) is dominant as a factor. On the other hand, for example, for example, when both the first and second line impedance influence degrees are smaller than both the first and second connection apparatus influence degrees, the determination unit 39 determines that the bias of the connection phase is a voltage error of the distribution line L100. It is determined (determined) to be dominant as a factor that increases the equilibrium.

  For example, when one of the first and second line impedance influence degrees is larger than one of the first and second connection apparatus influence degrees, the determination unit 39 determines that the deviation of the line impedance is that of the distribution line L100. It may be determined (determined) as dominant as a factor that increases voltage imbalance. In addition, for example, when one of the first and second line impedance influence degrees is smaller than one of the first and second connection device influence degrees, the determination unit 39 determines that the bias of the connection phase is that of the distribution line L100. It may be determined (determined) as dominant as a factor that increases voltage imbalance.

  Furthermore, as described above, the determination unit 39 determines whether or not the voltage imbalance rate of the distribution line L100 is equal to or less than a predetermined value (for example, 3%).

=== Countermeasures for voltage imbalance ===
Hereinafter, with reference to FIG. 8, the voltage imbalance countermeasure performed using the support apparatus in the present embodiment will be described. FIG. 8 is a flowchart showing a flow of voltage imbalance countermeasures performed using the support apparatus in the present embodiment. In steps St11 to St15, St17, and St20 to St22, an example of the operation of the support device 3 is shown.

  The support device 3 accepts system information (step St11). The support device 3 calculates each degree of influence based on the system information and the like (step St12). The support device 3 determines (determines) which of the bias of the connection phase and the bias of the line impedance is dominant as a factor that increases the voltage imbalance of the distribution line L100 based on each degree of influence ( Step St13). When both the first and second line impedance influence degrees are larger than both the first and second connection apparatus influence degrees (YES in Step St13), the support device 3 determines the distribution line L100 due to the deviation of the line impedance. A simulation for reducing the voltage imbalance rate is performed, the position where the distribution line L100 is to be bridged is determined, and the determination result is output (step St14). The support device 3 performs a simulation for reducing the voltage unbalance rate of the distribution line L100 due to the bias of the line impedance, determines a position where a device such as a single-phase reactor for the distribution line L100 should be provided, and the determination result Is output (step St15). In addition, as an output of the determination result in steps St14 and St15, for example, information based on the determination result may be displayed on the display device 34.

  Thereafter, for example, the administrator of the power distribution system 100 performs a countermeasure work for reducing the voltage imbalance rate based on the determination results of steps St14 and St15 (step St16).

  For example, the support device 3 determines whether or not the voltage unbalance rate of the distribution line L100 is equal to or less than a predetermined value in response to a request from the administrator of the distribution system 100 (step St17). When it is determined that the voltage imbalance rate of distribution line L100 is equal to or less than the predetermined value (YES in step St17), the voltage imbalance countermeasure is terminated.

  On the other hand, when it is determined that the voltage imbalance rate of the distribution line L100 is not less than or equal to the predetermined value (NO in step St17), it is determined whether or not to conduct a field survey in the distribution system 100 (step St18). If it is determined that no on-site survey is to be performed (NO in step St18), after the connection phase is repaired based on a predetermined standard, the voltage imbalance countermeasure is terminated. On the other hand, if it is determined that a field survey is to be performed (YES in step St18), a field survey is performed.

  Thereafter, the support device 3 creates system information reflecting the result of the field survey, and stores it in the storage device 33 (step St20). The support device 3 performs a simulation for reducing the voltage imbalance rate of the distribution line L100 due to the bias of the connection phase, determines the connection phase of the pole transformers 61 to 64, and outputs the determination result (step) St21). The support device 3 performs a simulation for reducing the voltage imbalance rate of the distribution line L100 due to the bias of the connection phase, determines a position where a device such as a single-phase reactor for the distribution line L100 should be provided, and the determination result Is output (step St22), and then the operation is terminated.

  In step St13, for example, when both the first and second line impedance influence degrees are smaller than both the first and second connection apparatus influence degrees (NO in step St13), the determination in step St18 is performed.

  As described above, the support device 3 includes the first calculation unit 36 and the determination unit 39. The first calculator 36 considers the load to be balanced, and calculates the first and second line impedance influence degrees according to the voltage unbalance rate under the first and second conditions. That is, the first calculation unit 36 is equivalent to the three sets of two phase transformers 61 to 64 connected to any two phases of the distribution lines L1 to L3. As a result, the first and second line impedance influence degrees are calculated. The first calculation unit 36 considers the line impedance to be balanced, and calculates the first and second connection phase influence degrees according to the voltage unbalance rate under the third and fourth conditions. That is, the 1st calculating part 36 calculates the 1st and 2nd connection phase influence degree supposing that the line impedance of the distribution lines L1-L3 is respectively equivalent. The determination unit 39 determines the cause of the occurrence of voltage imbalance in the distribution line L100 based on each degree of influence. With these configurations, the support device 3 can determine the cause of the voltage imbalance of the distribution line L100. For example, the voltage unbalance rate of the distribution line L100 can be reliably reduced by performing countermeasure work for reducing the voltage unbalance rate based on the cause of occurrence determined by the support device 3.

  Further, the determination unit 39 determines that the voltage imbalance occurs due to the deviation of the line impedance when the first and second line impedance influence degrees are larger than the first and second connection phase influence degrees, When the first and second line impedance influence degrees are smaller than the first and second connection phase influence degrees, it is determined that voltage imbalance occurs due to the bias of the connection phases. With this configuration, the support device 3 can determine the cause of the voltage imbalance relatively easily and reliably based on the magnitude relationship between the degrees of influence.

  In addition, the first calculation unit 36 sets the maximum values of the voltage imbalance rates under the first and second conditions as the first and second line impedance influence degrees. The first calculation unit 36 sets the maximum values of the voltage imbalance rates under the third and fourth conditions as the first and second connection phase influence degrees. With these configurations, the support device 3 can determine the cause of the voltage imbalance based on the maximum value of the voltage imbalance rate. For example, the maximum value of the voltage unbalance rate of the distribution line L100 can be reduced by performing a countermeasure work for reducing the voltage unbalance rate based on the cause of occurrence determined by the support device 3.

  The distribution line L100 is supported by a plurality of utility poles 81 to 84. The first calculation unit 36 calculates the first line impedance influence degree under the first condition. That is, the first calculation unit 36 calculates the first line impedance influence degree, assuming that the poles 4 are all used as the power poles 81 to 84. With this configuration, even when it is unclear as to which of the poles 4 and 5 is used as the electric poles 81 to 84, the support device 3 can determine the cause of the occurrence of voltage imbalance.

  In addition, the first calculation unit 36 calculates the second line impedance influence degree under the second condition. That is, the 1st calculating part 36 calculates a 2nd line impedance influence degree as the pole 5 is used as the electric poles 81 thru | or 84 all. With this configuration, even when it is unclear as to which of the poles 4 and 5 is used as the electric poles 81 to 84, the support device 3 can determine the cause of the occurrence of voltage imbalance. Further, for example, the support device 3 has a value between the range of the second line impedance influence degree and the first line impedance influence degree that can be taken by the maximum value of the voltage unbalance rate of the actual system in the distribution system 100. The cause of the voltage imbalance can be determined by regarding the range.

  Moreover, the 1st calculating part 36 calculates the 1st and 2nd line impedance influence degree supposing that the distribution line L100 is not laid. With this configuration, the support device 3 generates a voltage imbalance by, for example, calculating a relatively small value as the first and second line impedance influence degrees based on, for example, the position of the bridge in the power distribution system 100. It is possible to prevent erroneous determination of the cause. Accordingly, it is possible to improve the accuracy of determining the cause of occurrence of voltage imbalance by the support device 3.

  In addition, the first calculation unit 36 calculates the first connection phase influence degree under the third condition. That is, the 1st calculating part 36 calculates a 1st connection phase influence degree as performing connection phase arbitrary allocation. With this configuration, even when the phase of the connection destination of the pole transformers 61 to 64 to the distribution line L100 is unknown, the support device 3 can determine the cause of the occurrence of voltage imbalance.

  Further, the first calculation unit 36 calculates the fourth connection phase influence degree under the fourth condition. That is, the 1st calculating part 36 calculates a 2nd connection phase influence degree as performing the arbitrary allocation by the connection phase sum under equality. With this configuration, even when the phase of the connection destination of the pole transformers 61 to 64 to the distribution line L100 is unknown, the support device 3 can determine the cause of the occurrence of voltage imbalance. In addition, for example, the support device 3 has a range between the second connection phase influence degree and the first connection phase influence degree that is a value that the maximum value of the voltage unbalance rate of the real system in the distribution system 100 can take. The cause of the voltage imbalance can be determined by regarding the range.

  Moreover, the 1st calculating part 36 makes the maximum value in the average value of the voltage imbalance rate of each position for several times in the 3rd condition the 1st connection phase influence degree. The 1st calculating part 36 makes the maximum value in the average value of the voltage imbalance rate of each position for multiple times in 4th conditions the 2nd connection phase influence degree. With this configuration, the support device 3 can determine the cause of the voltage imbalance after grasping the occurrence of the voltage imbalance from the overall viewpoint of the average occurrence rate. In other words, for example, a relatively large value of the first and second connection phase influences can be obtained by intensively connecting pole transformers having a relatively large capacity to predetermined two phases of the distribution line L100. By calculating, it is possible to prevent erroneous determination of the cause of occurrence of voltage imbalance. Accordingly, it is possible to improve the accuracy of determining the cause of occurrence of voltage imbalance by the support device 3.

  In addition, the said embodiment is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  In the above embodiment, it has been described that the determination unit 39 determines which of the bias of the connection phase and the bias of the line impedance is dominant based on the magnitude relationship between the respective degrees of influence. It is not something that can be done. For example, the determination unit 39 may determine which of the connection phase bias and the line impedance bias is dominant based on the maximum influence degree among the influence degrees. In this case, for example, when the maximum influence degree of each influence degree is the first or second line impedance influence degree, the determination unit 39 increases the voltage imbalance of the distribution line L100 due to the deviation of the line impedance. Judgment (determination) is dominant as a factor. On the other hand, for example, when the maximum influence degree of each influence degree is the first or second connection apparatus influence degree, the determination unit 39 is a factor that increases the voltage imbalance of the distribution line L100 due to the bias of the connection phase. It is determined (determined) as dominant.

3 Supporting devices 4 and 5 Mounted column 36 First calculation unit 39 Determination units 61, 62, 63, 64 Pole transformers 81, 82, 83, 84 Power poles L1, L2, L3L100 Distribution line

Claims (10)

Considering that a plurality of pole transformers connected to any two phases of the three phases of the three-phase distribution lines are equally connected to each of the three phases of the three-phase distribution lines, the three-phase distribution lines A first arithmetic unit that calculates a line impedance influence degree according to the first voltage unbalance rate;
A second arithmetic unit that calculates the connection phase influence degree of the pole transformer according to the second voltage unbalance rate of the three-phase distribution line, assuming that the three phases of the three-phase distribution line have the same line impedance. When,
A determination device for determining the cause of voltage imbalance in the three-phase distribution line based on the line impedance influence degree and the connection phase influence degree,
An apparatus for determining the cause of occurrence of voltage imbalance, comprising: When the line impedance influence is greater than the connection phase influence, the determination device determines that the voltage imbalance occurs due to a deviation in line impedance of each of the three phases of the three-phase distribution line, When the line impedance influence degree is smaller than the connection phase influence degree, it is determined that the voltage imbalance occurs due to a two-phase deviation of the three-phase distribution line to which the plurality of pole transformers are connected. The apparatus for determining the cause of occurrence of voltage imbalance according to claim 1. The first arithmetic unit takes the maximum value of the first voltage imbalance ratios at a plurality of positions in the three-phase distribution line as the line impedance influence degree,
2. The voltage imbalance according to claim 1, wherein the second arithmetic unit uses, as the connection phase influence degree, a maximum value of the second voltage imbalance ratios at a plurality of positions in the three-phase distribution line. Equilibrium cause determination device. The three-phase distribution line is supported by a plurality of utility poles,
The first arithmetic unit further considers that three distribution lines in the three-phase distribution line are arranged along the horizontal direction with respect to all the plurality of utility poles, and calculates the line impedance influence degree. The apparatus for determining the cause of occurrence of voltage imbalance according to claim 1. The three-phase distribution line is supported by a plurality of utility poles,
The first arithmetic unit further considers that three distribution lines in the three-phase distribution line are arranged along a vertical direction with respect to all the plurality of utility poles, and calculates the line impedance influence degree. The apparatus for determining the cause of occurrence of voltage imbalance according to claim 1. 2. The determination of the cause of occurrence of voltage imbalance according to claim 1, wherein the first arithmetic unit further considers that the three-phase distribution lines are not stretched and calculates the line impedance influence degree. apparatus. The second arithmetic unit further calculates that the plurality of pole transformers are connected to the two phases of the three phases of the three-phase distribution line with an equal probability, and calculates the connection phase influence degree. The apparatus for determining the cause of occurrence of voltage imbalance according to claim 1. The second arithmetic unit further considers that the plurality of pole transformers are connected such that the number of pole transformers connected to two sets of three phases of the three-phase distribution line is equal, The connection phase influence degree is calculated. The apparatus for determining the cause of occurrence of voltage imbalance according to claim 1. The second arithmetic unit is
A third arithmetic unit that calculates the second voltage unbalance rate a plurality of times at each of a plurality of positions of the three-phase distribution line;
A fourth arithmetic unit that calculates the connection phase influence degree according to an average value of the second voltage unbalance rate for a plurality of times at each of the plurality of positions based on a calculation result of the third arithmetic unit. The apparatus for determining the cause of occurrence of voltage imbalance according to claim 1. Considering that a plurality of pole transformers connected to any two phases of the three phases of the three-phase distribution lines are equally connected to each of the three phases of the three-phase distribution lines, the three-phase distribution lines A first step of calculating a line impedance influence degree according to the first voltage imbalance rate;
A second step of calculating the connection phase influence degree of the pole transformer according to the second voltage unbalance rate of the three-phase distribution line, assuming that each of the three phases of the three-phase distribution line has an equivalent line impedance; ,
And a third step of determining a cause of occurrence of voltage imbalance in the three-phase distribution line based on the degree of influence of line impedance and the degree of influence of connection phase .

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