Voltage imbalance suppression support method and voltage imbalance suppression support device

Abstract

To provide a voltage unbalance suppression support method and a voltage unbalance suppression support device that can simulate the suppression of voltage unbalance in a three-phase distribution line using a V-Y connection TVR.SOLUTION: Using a power flow calculation method, when voltage unbalance suppression simulation of a three-phase distribution line according to the placement position of a thyristor-type automatic voltage regulator is performed, a target voltage of a first phase voltage to ground of the thyristor-type automatic voltage regulator, a target voltage of a second phase voltage to ground, a target voltage of a third phase voltage to ground, the regulated first phase voltage to ground, the regulated second phase voltage to ground, the regulated third phase voltage to ground, the tap value of a voltage regulating transformer connected in parallel between the first and second phases, and the tap value of a voltage regulating transformer connected in parallel between the second and third phases are used to add a correction term to keep the neutral point voltage unchanged.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a voltage imbalance suppression support method and a voltage imbalance suppression support device for a three-phase power distribution system. [Background technology]

[0002] In a power distribution system, three-phase AC power is transmitted by installing three-phase distribution lines in a horizontal or vertical arrangement on poles, and three-phase or single-phase AC power is supplied to power consumers such as ordinary homes, factories, and stores via pole-mounted transformers installed within the distribution area. The pole-mounted transformers are connected to any two of the three phases of the three-phase distribution line. Hereinafter, the single-phase portion following the pole-mounted transformer is referred to as the "single-phase load."

[0003] When single-phase loads are connected to two of the three phases of a three-phase distribution line, the current imbalance increases, and the degree of three-phase voltage imbalance (hereinafter referred to as voltage imbalance) of the three-phase AC voltage increases. In order to deal with such voltage imbalance and voltage fluctuations in three-phase distribution lines, the introduction of thyristor type automatic voltage regulators (TVRs) has been progressing in recent years (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6666109 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, automatic voltage regulators (SVRs: Step Voltage Regulators) have been installed as a countermeasure against voltage drops in distribution systems. SVRs do not have the function to suppress voltage imbalance because they switch the taps of all three phases at once, but the VY-connected TVR, which was developed in recent years, can suppress voltage imbalance by switching the taps for two phases independently. In order to take measures against voltage imbalance in a distribution system by installing equipment, it is necessary to install the equipment in an appropriate location. However, because the optimal installation location differs depending on the distribution system, in order to achieve efficient operation, it is necessary to derive the optimal installation location of the TVR in advance through simulation.

[0006] The present invention has been made in consideration of the above, and has an object to provide a voltage imbalance suppression support method and a voltage imbalance suppression support device that are capable of implementing a simulation of voltage imbalance suppression in a three-phase distribution line using a TVR with a VY connection. [Means for solving the problem]

[0007] In order to achieve the above object, a voltage imbalance suppression support method according to one embodiment is a voltage imbalance suppression support method that uses a power flow calculation method to perform a simulation of voltage imbalance suppression in a three-phase distribution line according to an arrangement position of a thyristor-type automatic voltage regulator, the thyristor-type automatic voltage regulator comprising: a Y-connected series transformer having a secondary winding connected in series to each of a first phase, a second phase, and a third phase; a V-connected voltage adjustment transformer connected in parallel between the first phase and the second phase, and between the second phase and the third phase, respectively; and a thyristor-type tap changer connected to the secondary winding of the voltage adjustment transformer and the primary winding of the series transformer; and a target voltage of a voltage to ground of the first phase is set to E a , the target voltage of the second phase to ground is E b , the target voltage of the third phase to ground is E c , the adjusted voltage to ground of the first phase is E A , the adjusted second phase voltage to ground is E B , the adjusted third phase voltage to ground is E C , the tap value of the voltage regulating transformer connected in parallel between the first and second phases is a Rab, the tap value of the voltage regulating transformer connected in parallel between the second and third phases is a Rbc Then, a simulation of voltage imbalance suppression for the three-phase distribution line is performed using the following equations (1) and (2).

[0008]

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[0009]

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[0010] As a desirable embodiment, a simulation of voltage imbalance suppression on the three-phase distribution line is performed assuming that the thyristor-type automatic voltage regulator is placed at one of multiple nodes from the distribution substation to the end of the three-phase distribution line.

[0011] In a preferred embodiment, a simulation of voltage imbalance suppression for the three-phase power distribution line, assuming that the thyristor-type automatic voltage regulator is disposed at one of the plurality of nodes, is performed for all of the plurality of nodes.

[0012] In order to achieve the above object, a voltage imbalance suppression support device according to one embodiment is a voltage imbalance suppression support device that uses a power flow calculation method to perform a simulation of voltage imbalance suppression in a three-phase distribution line according to an arrangement position of a thyristor-type automatic voltage regulator, the thyristor-type automatic voltage regulator comprising: a Y-connected series transformer having a secondary winding connected in series to each of a first phase, a second phase, and a third phase; a V-connected voltage adjustment transformer connected in parallel between the first phase and the second phase, and between the second phase and the third phase, respectively; and a thyristor-type tap changer connected to the secondary winding of the voltage adjustment transformer and the primary winding of the series transformer, and a target voltage of a voltage to ground of the first phase is set to E a , the target voltage of the second phase to ground is E b , the target voltage of the third phase to ground is E c , the adjusted voltage to ground of the first phase is E A , the adjusted second phase voltage to ground is EB , the adjusted third phase voltage to ground is E C , the tap value of the voltage regulating transformer connected in parallel between the first and second phases is a Rab , the tap value of the voltage regulating transformer connected in parallel between the second and third phases is a Rbc Then, a simulation of voltage imbalance suppression for the three-phase distribution line is performed using the following equations (1) and (2).

[0013]

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[0014]

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[0015] In a preferred embodiment, the voltage imbalance suppression support device performs a voltage imbalance suppression simulation for the three-phase distribution line, assuming that the thyristor-type automatic voltage regulator is placed at one of multiple nodes from a distribution substation to an end of the three-phase distribution line.

[0016] In a preferred embodiment, the voltage imbalance suppression support device performs a voltage imbalance suppression simulation for the three-phase distribution line, assuming that the thyristor-type automatic voltage regulator is placed at one of the multiple nodes, for all of the multiple nodes.

[0017] In a preferred embodiment, the voltage imbalance suppression support device outputs a result of a voltage imbalance suppression simulation of the three-phase distribution line performed for all of the plurality of nodes. Effect of the Invention

[0018] According to the present invention, it is possible to provide a voltage imbalance suppression support method and a voltage imbalance suppression support device that are capable of implementing a simulation of suppression of voltage imbalance in a three-phase distribution line using a TVR with a VY connection. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram showing an example of a three-phase power distribution system to which a voltage imbalance suppression supporting method according to the present embodiment is applied. [Diagram 2] FIG. 2 is a diagram illustrating an example of a load connected to a three-phase distribution line. [Diagram 3] FIG. 3 is a diagram showing an example of a horizontal pole mounting. [Figure 4] FIG. 4 is a diagram showing an example of a vertical mounting. [Diagram 5] FIG. 5 is a diagram showing an example of a two-line mounting pole (multiple-line mounting pole). [Figure 6] FIG. 6 is a voltage vector diagram showing an example of a voltage unbalance occurring in a three-phase distribution line. [Figure 7] FIG. 7 is a voltage vector diagram showing an example of a voltage unbalance occurring in a three-phase distribution line. [Figure 8] FIG. 8 is a diagram showing a single-phase power distribution line modeled as a ladder circuit to explain the concept of the FBS method. [Figure 9] FIG. 9 is a flowchart showing an example of a power flow calculation process using the FBS method. [Figure 10] FIG. 10 is a schematic diagram showing an example of a TVR applied in the voltage imbalance suppression support method according to the embodiment. [Figure 11] FIG. 11 is a voltage vector diagram showing an example of each interphase voltage before and after adjustment of the TVR. [Figure 12] FIG. 12 is a diagram illustrating an example of functional blocks of a voltage imbalance suppression support device according to an embodiment. [Figure 13] FIG. 13 is a flowchart illustrating an example of a voltage imbalance suppression support process in the voltage imbalance suppression support method according to the embodiment. [Figure 14] FIG. 14 is a diagram showing an example of a voltage imbalance restraint simulation result. [Figure 15] FIG. 15 is a diagram showing an example of a voltage imbalance restraint simulation result. [Figure 16] FIG. 16 is a diagram showing an example of a voltage imbalance restraint simulation result. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the following modes for carrying out the invention (hereinafter, referred to as embodiments). Furthermore, the components in the following embodiments include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiments can be appropriately combined.

[0021] FIG. 1 is a diagram showing an example of a three-phase power distribution system to which the voltage imbalance suppression support method according to the present embodiment is applied. In the three-phase power distribution system 100, three-phase power is transmitted from a distribution transformer 200 installed in a distribution substation to a three-phase power distribution line 101. The three-phase power distribution line 101 is divided into a plurality of sections (six sections in FIG. 1) at a predetermined interval X (for example, 1 km). In FIG. 1, the boundaries of each section of the three-phase power distribution line 101 are respectively designated as nodes ND1, ND2, ND3, ND4, and ND5, and the end of the three-phase power distribution line 101 is designated as node ND6. Hereinafter, when the nodes ND1, ND2, ND3, ND4, ND5, and ND6 are not particularly distinguished from one another, they are referred to as nodes ND. Note that the interval X between adjacent nodes ND does not necessarily have to be equal.

[0022] The distribution transformer 200 is a device that transforms, for example, a voltage on the primary side at a predetermined transformation ratio and outputs the transformed voltage from the secondary side. The distribution transformer 200 has a transformation ratio set so that, for example, a voltage of 66 [kV] is transformed to a voltage of 6600 [V].

[0023] The three-phase distribution line 101 is a power line for supplying power from a distribution transformer 200 to loads 2 connected to each section, and is mounted, for example, on utility poles (not shown) arranged at predetermined intervals. The loads 2 connected to each section each include one or more single-phase loads. In the example shown in FIG. 1, it is assumed that three-phase power is supplied from the left end side of the three-phase distribution line 101. Hereinafter, the left end side of the three-phase distribution line 101 will also be referred to as the "upstream side," and the right end side of the three-phase distribution line 101 will also be referred to as the "downstream side."

[0024] Each section of the three-phase distribution line 101 is, for example, a vertical pole section in which three-phase distribution lines, a, b, and c, are mounted in a vertical arrangement on poles, or a horizontal pole section in which three-phase distribution lines are mounted in a horizontal arrangement on poles.

[0025] 2 is a diagram showing an example of a load connected to a three-phase distribution line. Three-phase AC power, in which the amplitudes of the line voltages are equal and the phases of the line voltages differ by 120°, is supplied from a distribution transformer 200 to three-phase distribution lines a, b, and c constituting a three-phase distribution line 101.

[0026] The pole transformer 21 is a transformer that transforms, for example, a voltage on the primary side at a predetermined transformation ratio and outputs the transformed voltage from the secondary side. The pole transformer 21 is assumed to have a transformation ratio set so that a voltage of 6600 [V] is transformed to a voltage of 100 [V] or 200 [V]. The primary side of the pole transformer 21 is connected to any two of the three-phase distribution lines a, b, and c (i.e., any two phases of the a-phase, b-phase, and c-phase). FIG. 2 shows an example in which the primary side of the pole transformer 21 is connected to the distribution line a (a-phase) and the distribution line b (b-phase).

[0027] The load 22 is an electric power load provided in the three-phase power distribution system 100. The load 22 is connected to the three-phase power distribution line 101 via a pole transformer 21. The load 22 is an electric power load that operates by being supplied with electric power transformed by the pole transformer 21. The load 22 operates by being supplied with electric power of any two phases, for example, a phase and b phase, b phase and c phase, or c phase and a phase, via the pole transformer 21.

[0028] For convenience of explanation, a three-phase power load that is different from the above-mentioned load 2 and is connected to the three-phase power distribution system 100 is omitted. The three-phase power load is a power load that is connected to all three distribution lines a, b, and c of the three-phase power distribution line 101 and operates when power of all three phases, a, b, and c, is supplied.

[0029] Fig. 3 is a diagram showing an example of a horizontal pole mounting. In the horizontal pole mounting, the a-phase, b-phase, and c-phase distribution lines of a three-phase distribution line 101 are arranged horizontally with respect to the ground and mounted on the pole as shown in Fig. 3.

[0030] Fig. 4 is a diagram showing an example of a vertical pole mounting. In the vertical pole mounting, the a-phase, b-phase, and c-phase distribution lines of a three-phase distribution line 101 are arranged vertically with respect to the ground and mounted on a pole as shown in Fig. 3.

[0031] 5 is a diagram showing an example of a double-circuit pole (multiple-circuit pole). In the double-circuit pole (multiple-circuit pole), a plurality of three-phase distribution lines 101 are laid in parallel, and the a-phase, b-phase, and c-phase distribution lines of the three-phase distribution lines 101 are mounted on horizontal or vertical poles.

[0032] Next, a voltage imbalance in the three-phase power distribution system 100 will be described. In the three-phase power distribution system 100, there are two causes of voltage imbalance: asymmetry of phase arrangement and imbalance of load distribution. Here, the term "phase arrangement" refers to the positional relationship of the distribution lines a, b, and c of the three-phase power distribution line 101, and the term "voltage imbalance due to asymmetry of phase arrangement" refers to a voltage imbalance caused by asymmetric mutual impedance between lines due to the arrangement of the distribution lines a, b, and c in a horizontal pole or vertical pole in a row, or due to the influence of the distribution line of the other circuit in a double-circuit pole (multi-circuit pole). In addition, the term "load distribution" refers to the distribution of the load capacity for each connection phase, and the term "voltage imbalance due to imbalance of load distribution" refers to a voltage imbalance caused by an imbalance in the total capacity of the single-phase loads connected to each connection phase. In the following description, voltage unbalance due to asymmetric phase arrangement and voltage unbalance due to unbalanced load distribution will not be distinguished from each other, and will be simply referred to as "voltage unbalance."

[0033] Here, first, a voltage unbalance occurring in a three-phase distribution line 101 will be described with reference to Fig. 6 and Fig. 7. Fig. 6 and Fig. 7 are voltage vector diagrams showing an example of a voltage unbalance occurring in a three-phase distribution line. Fig. 6 shows the phase voltages of distribution lines a, b, and c. Fig. 7 shows the interphase voltages of distribution lines a, b, and c.

[0034] 6 and 7, the horizontal axis indicates the real axis Re, and the vertical axis indicates the imaginary axis Im. Here, the explanation will be made using the symmetric coordinate method. The positive-phase voltage of the three-phase distribution line 101 can be expressed by the following equation (2) using the voltage vectors of the a-phase, b-phase, and c-phase and the vector operator shown in the following equation (1). Moreover, the negative-phase voltage of the three-phase distribution line 101 can be expressed by the following equation (3) using the voltage vectors of the a-phase, b-phase, and c-phase and the vector operator shown in the following equation (1).

[0035]

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[0036]

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[0037]

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[0038] The voltage unbalance rate ε of the three-phase distribution line 101 can be expressed as a ratio between the positive-sequence voltage and the negative-sequence voltage of the three-phase distribution line 101, as shown in the following formula (4).

[0039]

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[0040] Moreover, the voltage unbalance rate ε of the three-phase distribution line 101 can be expressed by the following formulas (5) to (8) using the interphase voltages of the distribution lines a, b, and c.

[0041]

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[0042]

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[0043]

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[0045] In this disclosure, for example, in a three-phase power distribution system 100 shown in Fig. 1, a simulation is performed in which thyristor type step voltage regulators (TVRs, hereinafter also simply referred to as "TVRs") are placed at each of nodes ND1, ND2, ND3, ND4, ND5, and ND6, and a voltage imbalance suppression simulation is performed for the three-phase power distribution system 100 using the FBS (Forward / Backward Sweep) method (or the BSF (Backward / Forward Sweep) method, which will be unified as the "FBS method" in this disclosure), which is one of the power flow calculation methods in power systems. Here, for ease of explanation, the concept of the FBS method will first be explained by taking a single-phase power distribution line as an example.

[0046] Fig. 8 is a diagram showing a model of a single-phase power distribution line using a ladder circuit to explain the concept of the FBS method. Fig. 9 is a flowchart showing an example of a power flow calculation process using the FBS method.

[0047] In FIG. 8, node ND1 indicates the sending point of the distribution substation. The sending voltage V s In FIG. 8, the node ND N indicates the end of a single-phase distribution line. Z n,n+1 denotes the known node-to-node impedance of a single-phase distribution line. S n is a known load (P n [kW],Q n [kVar]).

[0048] In FIG. 8, an arbitrary node ND n The load current I n , voltage V n , Node ND n-1,n The current I n-1,n are expressed by the following equations (9), (10), and (11), respectively.

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[0050]

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[0052] In the FBS method, first, an arbitrary node ND n+1 Voltage at (=V n+1 ) is initialized as the target voltage of 6600 [V] (step S11), and the node ND n The above equations (9), (10), and (11) are executed for (step S12).

[0053] Thereafter, the above formulas (9), (10), and (11) are repeatedly executed up to node ND2. Specifically, after step S12, n is decremented (step S13), and it is determined whether n has become 2 (step S14).

[0054] If n is greater than 2 (step S14; No), the process returns to step S12, and the process up to step S14 is repeated.

[0055] When n becomes 2 (step S14; Yes), the current I calculated in the above formula (10) is n-1,n Using this, the node ND N The following equation (12) is executed until (step S15).

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[0057] Hereafter, Node ND N The above formula (12) is repeatedly executed until: Specifically, after step S15, n is incremented (step S16), and it is determined whether n has become N+1 (step S17).

[0058] If n is equal to or smaller than N (step S17; No), the process returns to step S15, and the processes up to step S17 are repeatedly executed.

[0059] When n becomes N+1 (step S17; Yes), the transmission voltage V s and the voltage V1 at node ND1 |V s -V1| is calculated (step S18), and the difference |V s It is determined whether -V1| is equal to or smaller than a predetermined value α (step S19).

[0060] Difference |V s If -V1| is greater than the predetermined value α (step S19; No), the process returns to step S12, and the process up to step S19 is repeated.

[0061] Difference |V s When -V1| becomes equal to or smaller than the predetermined value α (step S19; Yes), the power flow calculation process ends.

[0062] The above-described power flow calculation process makes it possible to perform a voltage simulation of the single-phase power distribution line shown in Fig. 8. Note that, although a single-phase power distribution line has been described as an example here, a voltage simulation can also be performed with a three-phase power distribution system 100 based on a similar concept.

[0063] In this disclosure, for example, in the three-phase power distribution system 100 shown in Fig. 1, it is assumed that a TVR is placed at any one of the nodes ND1, ND2, ND3, ND4, ND5, and ND6, and a voltage imbalance suppression simulation is performed using the above-mentioned FBS method. Here, an overview of a TVR (thyristor-type automatic voltage regulator) applied to the three-phase power distribution system 100 will be described with reference to Fig. 10.

[0064] 10 is a schematic diagram showing an example of a TVR applied in a voltage imbalance suppression support method according to an embodiment. As shown in FIG 10, this embodiment targets a TVR3 with a so-called VY connection, in which the upstream side is a Y connection and the downstream side is a V connection.

[0065] The TVR3 includes Y-connected series transformers 31A, 31B, 31C which connect secondary windings in series to each phase of the three-phase power distribution system 100, V-connected voltage regulating transformers 32ab, 32bc which are connected in parallel between each phase of the three-phase power distribution system 100, and a thyristor tap changer 33 connected to the secondary windings of the voltage regulating transformers 32ab, 32bc and the primary windings of the series transformers 31A, 31B, 31C.

[0066] The thyristor tap changer 33 includes a plurality of thyristors (not shown). When the voltage of the power distribution line fluctuates due to a load fluctuation, the thyristor tap changer 33 performs tap switching of each thyristor so as to reduce the difference between the primary voltage of the power distribution line and a reference voltage.

[0067] In the TVR 3 shown in FIG. 10, the thyristor tap changer 33 controls the phase-to-phase voltage of the ab phase and the phase-to-phase voltage of the bc phase separately. This allows the VY-connected TVR 3 to suppress voltage imbalance in the three-phase power distribution system 100. ab , V bc , V ca Then, the adjusted interphase voltage V AB , V BC , V CA The vector calculation formula is given by the following formula (13).

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[0069] In the above formula (13), a Rab indicates the tap value of the voltage regulating transformer 32ab, and a Rbc indicates the tap value of the voltage regulating transformer 32bc.

[0070] In the above-mentioned voltage simulation, the power flow calculation process is performed using the voltage to ground, i.e., each phase voltage. ab , V bc , V cais the reference voltage E for the target voltage of each phase (e.g., 6600 [V]). a ,E b ,E c Using this, it is expressed by the following equation (14).

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[0072] In addition, the adjusted phase voltage E A ',E B ',E C ' is expressed by the following equation (15).

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[0074] From the above equations (14) and (15), the following equation (16) is derived.

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[0076] Moreover, the VY-connected TVR 3 shown in Fig. 10 has the characteristic that the zero-phase sequence voltage does not change before and after adjustment. In the above equation (16), the neutral point information is lost. For this reason, it is necessary to add a correction term to the above equation (16) to set the zero-phase sequence voltage to "0" and to prevent the neutral point voltage from changing. Fig. 11 is a voltage vector diagram showing an example of each interphase voltage before and after TVR adjustment.

[0077] The zero-phase voltage of the three-phase distribution line 101 is expressed by the following equation (17) using the symmetric coordinate method described with reference to FIGS.

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[0079] Therefore, the regulated phase voltage EA ,E B ,E C The vector calculation equation is given by the following equation (18) by adding the correction term for the zero-phase voltage shown in the above equation (17) to the above equation (16).

[0080]

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[0081] On the other hand, the regulated phase current I A ', I B ', I C The vector calculation formula for ' is given by the following formula (19).

[0082]

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[0083] Similarly, in the above equation (19), the neutral point information is lost. For this reason, it is necessary to add a correction term to the above equation (19) to set the zero-phase current to "0" and to prevent the neutral point voltage from changing. Therefore, the adjusted phase current I A , I B , I C The vector calculation formula is given by the following formula (20) by adding a correction term for the zero-phase current to the above formula (19).

[0084]

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[0085] Here, we will explain a specific example of a voltage imbalance suppression support process for the three-phase power distribution system 100, assuming that a TVR3 shown in Figure 10 is placed at each node ND1, ND2, ND3, ND4, ND5, and ND6 of the three-phase power distribution system 100 shown in Figure 1.

[0086] 12 is a diagram showing an example of a functional block of a voltage imbalance suppression support device according to an embodiment. As shown in FIG. 12, the voltage imbalance suppression support device 1 according to the present embodiment includes, for example, an input unit 11, an output unit 12, a display unit 13, a storage unit 14, a connection phase determination unit 15, and a control unit 16.

[0087] The input unit 11 is, for example, a keyboard for inputting information to the voltage imbalance suppression support device 1.

[0088] The output unit 12 is, for example, a printer for outputting information to the outside of the voltage imbalance suppression support device 1.

[0089] The display unit 13 is, for example, a monitor for displaying information input to the voltage imbalance suppression supporting device 1 and information output from the voltage imbalance suppression supporting device 1.

[0090] The storage unit 14 is, for example, a ROM (Read Only Memory), a hard disk drive, a flash memory, or the like, or a combination of these.

[0091] The storage unit 14 stores, for example, a program for operating the voltage imbalance suppression support device 1. The storage unit 14 further stores, for example, a program for performing a voltage imbalance suppression support process (hereinafter also referred to as a "voltage imbalance suppression support process program").

[0092] The storage unit 14 also stores in advance various types of information related to the three-phase power distribution system 100. The various types of information related to the three-phase power distribution system 100 include, for example, known inter-node impedances of the three-phase power distribution line 101 and known loads connected to the three-phase power distribution line 101. The storage unit 14 also has a function of storing various types of data calculated in the voltage imbalance suppression support process.

[0093] The processing unit 15 performs a voltage imbalance suppression support process based on various information related to the three-phase power distribution system 100 stored in the storage unit 14.

[0094] The control unit 16 controls the operation of the voltage imbalance suppression support device 1 based on, for example, a program for operating the voltage imbalance suppression support device 1, which is stored in the storage unit 14. In addition, the control unit 16 starts up a voltage imbalance suppression support processing program, whereby the processing unit 15 executes the voltage imbalance suppression support processing.

[0095] The processing unit 15 and the control unit 16 can be configured by combining, for example, a CPU (Central Processing Unit) and a memory.

[0096] FIG. 13 is a flowchart illustrating an example of a voltage imbalance suppression support process in the voltage imbalance suppression support method according to the embodiment.

[0097] When the voltage imbalance suppression support processing program is started by the operator of the voltage imbalance suppression support device 1, the processing unit 15 reads out various information related to the three-phase power distribution system 100 stored in the memory unit 14, and executes the voltage imbalance suppression support processing shown in FIG. 13.

[0098] The processing unit 15 performs a voltage imbalance suppression simulation assuming that the TVR 3 is placed at an arbitrary node NDn (for example, node ND1) of the three-phase power distribution system 100. Specifically, the processing unit 15 assumes that the TVR 3 is placed at the node NDn, and calculates the target voltages (each-phase reference voltage E a ,E b ,E c ) is set to, for example, 6600 [V] (step S1). Then, the processing unit 15 uses the above-mentioned formulas (16) and (17) to calculate the adjusted phase voltages E A ,E B ,E C and using the above-mentioned equations (19) and (20), the adjusted phase current I A , I B , I C (Step S2) The processes of Step S1 and Step S2 correspond to the initial setting (Step S11) of the power flow calculation process shown in FIG.

[0099] The processing unit 15 calculates each phase voltage E A ,E B ,E C and each phase current I A , I B , I C Using this, a power flow calculation process (see FIG. 9) is performed for each phase (step S3).

[0100] The data calculated in the power flow calculation process is appropriately stored in the storage unit 14. Then, the processing unit 15 calculates the voltage unbalance rate εx for each node NDx using the above equations (1) to (8) based on the data stored in the storage unit 14 (voltage unbalance rate calculation process), and stores the voltage unbalance rate εx in the storage unit 14 (step S4).

[0101] The processing unit 15 judges whether or not the voltage imbalance suppression simulation (power flow calculation process (step S3) and voltage imbalance rate calculation process (step S4)) assuming that TVR3 is placed at all nodes NDx has been completed (step S5). If the voltage imbalance suppression simulation assuming that TVR3 is placed at all nodes NDx has not been completed (step S5; No), the processing unit 15 returns to step S1 and repeatedly executes the processes from step S1 to step S5 until the voltage imbalance suppression simulation assuming that TVR3 is placed at all nodes NDx has been completed.

[0102] When the voltage imbalance suppression simulation assuming placement of TVR3 at all nodes NDx is completed (step S5; Yes), the processing unit 15 generates charts, for example, as shown in Figures 14, 15, and 16 from various data stored in each node memory unit 14, and performs output processing such as displaying the charts on the display unit 13 or outputting the charts from the output unit 12 as the voltage imbalance suppression simulation results (step S6), and terminates the voltage imbalance suppression support processing.

[0103] 14, 15, and 16 are diagrams showing examples of the results of the voltage imbalance restraint simulation.

[0104] 14 and 15, the horizontal axis indicates the relative distance of each node ND to the distribution substation of the three-phase power distribution system 100 shown in FIG. 1, and the vertical axis indicates the line voltage. FIG. 14 shows the results of a simulation of the line voltage when it is assumed that a TVR 3 is placed at the node ND2 of the three-phase power distribution system 100 shown in FIG. 1. FIG. 15 shows the results of a simulation of the line voltage when a TVR 3 is not placed at any of the nodes ND of the three-phase power distribution system 100 shown in FIG. 1. In FIGS. 14 and 15, the solid lines indicate the line voltage V bc The dashed line indicates the line voltage V ca The dashed line indicates the line voltage V ab This shows that.

[0105] In Fig. 16, the horizontal axis indicates the relative distance of each node ND to the distribution substation of the three-phase power distribution system 100 shown in Fig. 1, and the vertical axis indicates the voltage unbalance rate. In Fig. 16, the solid line indicates the simulation result of the voltage unbalance rate when it is assumed that a TVR3 is placed at the node ND2 of the three-phase power distribution system 100 shown in Fig. 1, and the dashed line indicates the simulation result of the voltage unbalance rate when a TVR3 is not placed at any node ND of the three-phase power distribution system 100 shown in Fig. 1.

[0106] As shown in Fig. 14 and Fig. 16, voltage imbalance is suppressed at node ND2 where it is assumed that TVR3 is arranged. As a result, as shown in Fig. 16, it can be seen that the voltage imbalance rate of node ND2 where the voltage imbalance rate is the maximum value when it is assumed that TVR3 is arranged at node ND2 is 1 / 2 or less (approximately 0.7[%] or less in the example shown in Fig. 16) compared to the voltage imbalance rate of node ND6 where the voltage imbalance rate is the maximum value when TVR3 is not arranged at any node ND in three-phase power distribution system 100 (approximately 1.4[%] in the example shown in Fig. 16).

[0107] 14 and 15, the line voltage V at the end of the three-phase distribution line 101 (node ​​ND6 in the example shown in FIG. 1) when it is assumed that the TVR 3 is placed at the node ND2 is ab ,V bc ,Vca The variation in the line voltage V at the end of the three-phase distribution line 101 (here, node ND6) when the TVR 3 is not placed at any node ND of the three-phase distribution system 100 is ab ,V bc ,V ca This makes it possible to increase the control margin for the voltage control value (95[V] to 105[V]) when converted to 100[V], for example.

[0108] In the above example, in order to simplify the chart, the simulation result of the line voltage when it is assumed that the TVR3 is arranged at the node ND2 of the three-phase power distribution system 100 is shown in FIG. 14, and the simulation result of the line voltage when the TVR3 is not arranged at any node ND is shown in FIG. 15. However, for example, the simulation result of the line voltage when it is assumed that the TVR3 is arranged at the node ND2 of the three-phase power distribution system 100 shown in FIG. 14 and the simulation result of the line voltage when the TVR3 is not arranged at any node ND shown in FIG. 15 may be displayed in a superimposed manner on the display unit 13 or output from the output unit 12. This makes it easy to compare the presence and absence of the TVR3. Also, FIG. 14, FIG. 15, and FIG. 16 may be displayed in a superimposed manner or output from the output unit 12. This improves the visibility of the simulation result.

[0109] 14 shows an example of a chart illustrating a simulation result of line voltages when it is assumed that the TVR 3 is placed at node ND2 in the three-phase power distribution system 100 shown in Fig. 1, but in the above-mentioned voltage imbalance suppression support process, the processing unit 15 generates charts such as those shown in Fig. 14 and Fig. 16 as voltage imbalance suppression simulation results assuming that the TVR 3 is placed at all nodes NDx, and performs output processing such as displaying the charts on the display unit 13 or outputting the charts from the output unit 12. This makes it possible to consider the location (node ​​ND) where the TVR 3 is placed in the actual three-phase power distribution system 100.

[0110] Moreover, the form of the chart generated as the result of the voltage imbalance suppression simulation is not limited to the forms shown in Fig. 14, Fig. 15, and Fig. 16. For example, a form including more data than is calculated in the power flow calculation process may be used, or a form in which a threshold value is set for the voltage imbalance rate, and a chart capable of determining whether or not the voltage imbalance rate at each node ND clears the threshold value by the above-mentioned voltage imbalance suppression simulation may be used.

[0111] As described above, in the voltage imbalance suppression support method according to the present embodiment, when a voltage imbalance suppression simulation of the three-phase distribution line 101 according to the arrangement position of the TVR 3 in the VY connection is performed using the power flow calculation method, the target voltage E a , the target voltage E of the b-phase voltage to ground b , the target voltage E of the c-phase voltage to ground c , adjusted a-phase voltage to ground E A , adjusted b-phase voltage to ground E B , adjusted c-phase voltage to ground E C , the tap value a of the voltage adjusting transformer 32ab connected in parallel between the a-phase and the b-phase Rab , the tap value a of the voltage regulating transformer 32bc connected in parallel between phases b and c Rbc A voltage simulation is performed using the above formula, with a correction term added to prevent the neutral point voltage from changing.

[0112] This makes it possible to realize a voltage imbalance suppression simulation for the three-phase distribution line 101 using the TVR 3 with a VY connection.

[0113] In addition, the voltage imbalance suppression support method according to this embodiment performs a voltage imbalance suppression simulation for the three-phase distribution line 101, assuming that a TVR3 is placed at one node NDn among multiple nodes NDx from the distribution substation to the end of the three-phase distribution line 101.

[0114] More specifically, a voltage imbalance suppression simulation for the three-phase distribution line 101 assuming that the TVR 3 is placed at one of the multiple nodes NDx is performed for all of the multiple nodes NDx.

[0115] In addition, when performing a voltage imbalance suppression simulation of the three-phase distribution line 101 according to the arrangement position of the TVR 3 in the VY connection by using a power flow calculation method, the voltage imbalance suppression support device 1 according to the present embodiment calculates a target voltage E a , the target voltage E of the b-phase voltage to ground b , the target voltage E of the c-phase voltage to ground c , adjusted a-phase voltage to ground E A , adjusted b-phase voltage to ground E B , adjusted c-phase voltage to ground E C , the tap value a of the voltage adjusting transformer 32ab connected in parallel between the a-phase and the b-phase Rab , the tap value a of the voltage regulating transformer 32bc connected in parallel between phases b and c Rbc A voltage simulation is performed using the above formula, with a correction term added to prevent the neutral point voltage from changing.

[0116] This makes it possible to realize a voltage imbalance suppression simulation for the three-phase distribution line 101 using the TVR 3 with a VY connection.

[0117] In addition, the voltage imbalance suppression support device 1 according to this embodiment performs a voltage imbalance suppression simulation for the three-phase distribution line 101, assuming that a TVR3 is placed at one node NDn among multiple nodes NDx from the distribution substation to the end of the three-phase distribution line 101.

[0118] More specifically, a voltage imbalance suppression simulation for the three-phase distribution line 101 assuming that the TVR 3 is placed at one of the multiple nodes NDx is performed for all of the multiple nodes NDx.

[0119] Then, the voltage imbalance suppression supporting device 1 outputs the result of the voltage imbalance suppression simulation of the three-phase distribution line 101 performed for all of the multiple nodes NDx.

[0120] This makes it possible to consider the location (node ​​ND) where the TVR 3 is to be placed in the actual three-phase power distribution system 100. [Explanation of symbols]

[0121] 1. Voltage imbalance suppression support device 2. Load 3 TVR (Thyristor Type Automatic Voltage Regulator) 11 Input section 12 Output section 13 Display section 14 Storage section 15 Connection phase determination section 16 Control section 21 Pole transformer 22 Load 31A, 31B, 31C Series transformers 32ab, 32bc Voltage Regulating Transformer 33 Thyristor tap changer 100 Three-phase distribution system 101 Three-phase distribution line 200 Distribution Transformers

Claims

1. A voltage imbalance suppression support method for performing a voltage imbalance suppression simulation of a three-phase distribution line according to an arrangement position of a thyristor-type automatic voltage regulator using a power flow calculation method, comprising: The thyristor type automatic voltage regulator comprises: a series transformer having a Y connection in which a secondary winding is connected in series to each of the first phase, the second phase, and the third phase; a V-connection voltage adjusting transformer connected in parallel between the first phase and the second phase and between the second phase and the third phase, respectively; a thyristor tap changer connected to a secondary winding of the voltage regulating transformer and a primary winding of the series transformer; Equipped with The target voltage of the first phase to ground is E ａ , the target voltage of the second phase to ground is E ｂ , the target voltage of the third phase to ground is E ｃ , the adjusted first phase voltage to ground is E Ａ , the adjusted second phase voltage to ground is E Ｂ , the adjusted third phase voltage to ground is E Ｃ , the tap value of the voltage adjusting transformer connected in parallel between the first phase and the second phase is a Ｒａｂ , the tap value of the voltage adjusting transformer connected in parallel between the second and third phases is a Ｒｂｃ When the above equations are set, a simulation of suppressing voltage imbalance in the three-phase distribution line is performed using the following equations (1) and (2): A method for assisting in suppressing voltage imbalance. [0010] [0025]

2. A simulation of voltage imbalance suppression for the three-phase distribution line is performed on the assumption that the thyristor-type automatic voltage regulator is disposed at one of a plurality of nodes from a distribution substation to a terminal of the three-phase distribution line. The voltage imbalance suppression support method according to claim 1 .

3. performing a voltage imbalance suppression simulation for the three-phase distribution line, assuming that the thyristor-type automatic voltage regulator is disposed at one of the plurality of nodes, for all of the plurality of nodes; The voltage imbalance suppression support method according to claim 2 .

4. A voltage imbalance suppression support device that performs a voltage imbalance suppression simulation of a three-phase distribution line according to the arrangement position of a thyristor-type automatic voltage regulator using a power flow calculation method, The thyristor type automatic voltage regulator comprises: a series transformer having a Y connection in which a secondary winding is connected in series to each of the first phase, the second phase, and the third phase; a V-connection voltage adjusting transformer connected in parallel between the first phase and the second phase and between the second phase and the third phase, respectively; a thyristor tap changer connected to a secondary winding of the voltage regulating transformer and a primary winding of the series transformer; Equipped with The voltage imbalance suppression support device is The target voltage of the first phase to ground is E ａ , the target voltage of the second phase to ground is E ｂ , the target voltage of the third phase to ground is E ｃ , the adjusted first phase voltage to ground is E Ａ , the adjusted second phase voltage to ground is E Ｂ , the adjusted third phase voltage to ground is E Ｃ , the tap value of the voltage adjusting transformer connected in parallel between the first phase and the second phase is a Ｒａｂ , the tap value of the voltage adjusting transformer connected in parallel between the second and third phases is a Ｒｂｃ When the above equations are set, a simulation of suppressing voltage imbalance in the three-phase distribution line is performed using the following equations (1) and (2): Voltage imbalance suppression support device. [0010] [0025]

5. The voltage imbalance suppression support device is A simulation of voltage imbalance suppression for the three-phase distribution line is performed on the assumption that the thyristor-type automatic voltage regulator is disposed at one of a plurality of nodes from a distribution substation to a terminal of the three-phase distribution line. The voltage imbalance suppression assisting device according to claim 4.

6. The voltage imbalance suppression support device is performing a voltage imbalance suppression simulation for the three-phase distribution line, assuming that the thyristor-type automatic voltage regulator is disposed at one of the plurality of nodes, for all of the plurality of nodes; The voltage imbalance suppression support device according to claim 5.

7. The voltage imbalance suppression support device is outputting a result of the voltage imbalance suppression simulation of the three-phase distribution line performed for all of the plurality of nodes; The voltage imbalance suppression assist device according to claim 6.

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