Three-phase power conversion system

Abstract

To provide a three-phase power conversion system capable of suppressing three-phase unbalanced power of the whole power system while suppressing load increase of another power source and power transmission line.SOLUTION: A three-phase power conversion system comprises a first limiter part, a second limiter part, a first automatic voltage adjustment part, a second automatic voltage adjustment part, a first fixed factor control part, a second fixed factor control part, a first lower limit adjustment part, and a second lower limit adjustment part. The first limiter part outputs a voltage effective value of a first system as a value equal to or lower than a first upper limit value and equal to or higher than a first lower limit value. The second limiter part outputs a voltage effective value of a second system having a phase differing from that of the first system by 90 degrees, as a value equal to or lower than a second upper limit value and equal to or higher than a second lower limit value. The first lower limit adjustment part adjusts the first lower limit value on the basis of a power difference or a current difference between the first system and the second system. The second lower limit adjustment part adjusts the second lower limit value on the basis of the power difference or the current difference.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to power conversion systems. [Background technology]

[0002] When AC electric railway vehicles are designed for 60Hz only, the 50Hz power must be converted to 60Hz power before being supplied to the vehicles. Therefore, the power system that supplies power to the vehicles requires a frequency converter (hereafter referred to as FC) that converts the power frequency from 50Hz to 60Hz.

[0003] In addition, due to improvements in the acceleration performance of trains and the increasing density of train schedules, it can be difficult to stably supply power to trains when the power transmission distance from the power source is long. However, strengthening the power source and power transmission lines requires cost and time.

[0004] Therefore, the power conversion control device described in Patent Document 1 acquires the voltage measured at the connection point between the static FC connected to the power grid and the power grid, and supplies power from the static FC to the power grid at a fixed power factor in accordance with fluctuations in the acquired voltage.

[0005] Furthermore, the power conversion system described in the cited document 2 measures the current value supplied to at least the terminal power grid in addition to the voltage at the connection point, and based on the measured current value, increases the lower limit of the voltage at which the static FC starts output when the train load increases beyond a threshold. This realizes the supply of power from the static FC to the power grid while suppressing the increase in load on other power sources and transmission lines when the train load increases. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-191714 A [Patent Document 2] Patent Publication No. 2022-129171 Summary of the Invention [Problem to be solved by the invention]

[0007] The three-phase AC power output from the static FC is converted into two systems of single-phase AC power with a phase difference of 90 degrees, and then supplied to the train load. It has been discovered that even if the voltages of the two systems are normal, the three-phase line voltage and phase voltage may become excessive. If excessive voltage is applied to power equipment, it may cause problems for the power equipment, so it is desirable to suppress excessive line voltage and excessive phase voltage. To achieve this, it is considered effective to suppress the three-phase unbalanced power in the entire power system, but the above power conversion system does not have a function to suppress the three-phase unbalanced power.

[0008] An object of the present disclosure is to provide a three-phase power conversion system capable of suppressing an increase in the load on other power sources and power transmission lines, and further suppressing three-phase unbalanced power in the entire power system. [Means for solving the problem]

[0009] The three-phase power conversion system disclosed herein is applied to a power system that supplies power from a power source to a plurality of substations and train loads via a power transmission line, and includes a first limiter unit, a second limiter unit, a first automatic voltage regulator unit, a second automatic voltage regulator unit, a first fixed power factor controller unit, a second fixed power factor controller unit, a first lower limit regulator unit, and a second lower limit regulator unit. The first limiter unit receives an effective value of a first voltage corresponding to a single-phase voltage of a first system at a connection point where the three-phase power conversion system is connected to the power transmission line, and outputs the effective value of the inputted first voltage as a value that is equal to or less than a first upper limit value and equal to or more than a first lower limit value. The second limiter unit receives an effective value of a second voltage corresponding to a single-phase voltage of a second system having a phase difference of 90 degrees with the first system at the connection point, and outputs the effective value of the inputted second voltage as a value that is equal to or less than a second upper limit value and equal to or more than a second lower limit value. The first automatic voltage regulator and the first fixed power factor controller calculate a first output command value for the three-phase power conversion system based on a voltage difference obtained by subtracting the effective value of the first voltage from the output value of the first limiter so that the power factor of the output power becomes a predetermined value. The second automatic voltage regulator and the second fixed power factor controller calculate a second output command value for the three-phase power conversion system based on a voltage difference obtained by subtracting the effective value of the second voltage from the output value of the second limiter so that the power factor of the output power becomes a predetermined value. The first lower limit adjuster adjusts the first lower limit value based on a first active power value corresponding to the active power value of the first system at a predetermined position on the power transmission line or a first active current value corresponding to the active current value of the first system, and further adjusts the first lower limit value based on a power difference between the first active power value and a second active power value corresponding to the active power value of the second system at the predetermined position or a current difference between the first active current value and a second active current value corresponding to the active current value of the second system at the predetermined position. The second lower limit adjusting unit adjusts the second lower limit value based on the second active power value or the second active current value, and further adjusts the second lower limit value based on the power difference or the current difference.

[0010] By applying the above-mentioned three-phase power conversion system to a power system, it is possible to suppress an increase in the load on other power sources and transmission lines when the train load increases, while also suppressing three-phase unbalanced power in the entire power system. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing an example of a power system to which a three-phase power conversion system according to an embodiment of the present invention is applied. [Diagram 2] 2 is a block diagram showing a functional configuration of a control device of the three-phase power conversion system according to the present embodiment. FIG. [Diagram 3] 2 is a diagram showing line voltages in a power system to which the three-phase power conversion system according to the present embodiment is applied. FIG. [Figure 4] FIG. 1 is a diagram showing line voltages in a power system according to Patent Document 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a three-phase power conversion system 30 according to the present embodiment will be described with reference to the drawings. The three-phase power conversion system 30 is applied to a power system that supplies power supplied from a power source such as a rotary FC or a power company substation to a train load.

[0013] 1 is an example of a power system to which a three-phase power conversion system 30 is applied. The power system 100 includes a power source PS, a plurality of substations 21-24, power transmission lines 1-4, a current sensor CT, a voltage sensor VS1, a voltage sensor VS2, a power calculation unit 31, and the three-phase power conversion system 30.

[0014] In this embodiment, the power transmission range from the conventional power source PS before application of the three-phase power conversion system 30 is the range from the substation 21 to the substation 22, and the power transmission range from the power source PS after application of the three-phase power conversion system 30 is the range from the substation 21 to the substation 24. In other words, the expanded power transmission range due to application of the three-phase power conversion system 30 is the range from the substation 22 to the substation 24.

[0015] The power source PS is a power source such as a rotary type FC or a power company substation. The power source PS supplies three-phase AC power of R phase, S phase, and T phase to the substations 21-24. Each of the substations 21-24 includes a transformer that converts three-phase AC power supplied from the power source PS via the power transmission lines 1-4 into single-phase AC power and outputs the power. In this embodiment, each of the substations 21-24 includes, for example, a Scott connection transformer. The Scott connection transformer converts three-phase AC voltage into two single-phase voltage systems, M phase and T phase, having a phase difference of 90 degrees, and outputs the voltages. Therefore, each of the substations 21-24 outputs single-phase AC power of M phase and single-phase AC power of T phase. The single-phase AC powers of M phase and T phase output from the substations 21-24 are supplied to a train load.

[0016] The power transmission line 1 is connected between a power source PS and a substation 21. The power transmission line 2 is connected between the substation 21 and the substation 22. The power transmission line 3 is connected between the substation 22 and the substation 23. The power transmission line 4 is connected between the substation 23 and the substation 24.

[0017] The current sensor CT is installed in the power transmission line 2. The current sensor CT measures the current values ​​of at least two phases of the three-phase AC power output from the substation 21. The current sensor CT transmits the measured current values ​​to the power calculation unit 31. It is desirable that the current sensor CT measures at least the current value supplied to the terminal current system. It is desirable to install the current sensor CT, for example, in the vicinity of the substation 22 of the power transmission line 2, which is the front stage of the expanded power transmission range.

[0018] The voltage sensor VS1 is installed at a predetermined position on the power transmission line 2. The predetermined position is a position where a current value is detected by the current sensor CT. The voltage sensor VS1 measures at least two-phase voltage values. The voltage sensor VS1 measures the voltage value at the predetermined position and transmits the measured voltage value to the power calculation unit 31.

[0019] The power calculation unit 31 acquires at least two-phase current values ​​measured by the current sensor CT and at least two-phase voltage values ​​measured by the voltage sensor VS1, and calculates active power values ​​of each of the R-phase, S-phase, and T-phase supplied from the power transmission line 2 to the substation 22. Furthermore, the power calculation unit 31 converts the three-phase active power values ​​consisting of the R-phase, S-phase, and T-phase into an M-phase equivalent active power value and a T-phase equivalent active power value, and transmits these to the control device 360 ​​(see FIG. 2) of the three-phase power conversion system 30. The control device 360 ​​outputs the received M-phase equivalent active power value to the M-phase filter unit 32, and outputs the T-phase equivalent active power value to the T-phase filter unit 33.

[0020] In another embodiment, the power calculation unit 31 may calculate the M-phase equivalent active current value and the T-phase equivalent active current value, and transmit them to the control device 360. In that case, the power calculation unit 31 acquires at least two-phase current values ​​measured by the current sensor CT and at least two-phase voltage values ​​measured by the voltage sensor VS1, and calculates each active current value of the R phase, the S phase, and the T phase supplied from the transmission line 2 to the substation 22. Furthermore, the power calculation unit 31 converts the three-phase active current values ​​consisting of the R phase, the S phase, and the T phase into an M-phase equivalent active current value and a T-phase equivalent active current value, and transmits them to the control device 360. The control device 360 ​​outputs the received M-phase equivalent active current value to the M-phase filter unit 32, and outputs the T-phase equivalent active current value to the T-phase filter unit 33.

[0021] The voltage sensor VS2 is installed at a connection point PP of the power transmission line 4. The connection point PP is a position on the power transmission line 4 to which the three-phase power conversion system 30 is connected. The voltage sensor VS2 measures an effective voltage value of the power transmission line 4 at the connection point PP, and transmits the measured effective voltage value to the control device 360 ​​of the three-phase power conversion system 30.

[0022] The three-phase power conversion system 30 is connected to a power transmission line at a position away from the power source PS. In this embodiment, the three-phase power conversion system 30 is connected to a connection point PP, which is a position on the power transmission line 4, near an end of the power system 100. The three-phase power conversion system 30 converts three-phase AC power of a first frequency into three-phase AC power of a second frequency and supplies the three-phase AC power to a predetermined substation. In this embodiment, the first frequency is 50 Hz, the second frequency is 60 Hz, and the three-phase power conversion system 30 supplies the three-phase AC power to the substations 21 to 24.

[0023] The three-phase power conversion system 30 includes a transformer 310, a converter 320, a DC capacitor 330, an inverter 340, a transformer 350, and a control device 360 ​​shown in FIG.

[0024] The transformer 310 converts the three-phase AC voltage of a first frequency input to the three-phase power conversion system 30 into a predetermined voltage. The converter 320 converts the voltage output from the transformer 310 into a DC voltage, and outputs the DC voltage to the inverter 340 via the DC capacitor 330. The inverter 340 converts the DC voltage input from the converter 320 into a three-phase AC voltage of a second frequency, and outputs the three-phase AC voltage to the transformer 350. The transformer 350 converts the three-phase AC voltage input from the inverter 340 into a predetermined voltage, and outputs it to the substations 21-24.

[0025] Next, the function of the control device 360 ​​will be described with reference to Fig. 2. The control device 360 ​​includes the M-position filter unit 32, the T-position filter unit 33, the subtractor 42, the M-position compensation adjustment unit 34, the T-position compensation adjustment unit 35, the M-position adder 43, the T-position adder 44, the M-position gain units 36U and 36B, the T-position gain units 37U and 37B, the M-position upper limit adjustment unit 38U, the M-position lower limit adjustment unit 38B, the T-position upper limit adjustment unit 39U, the T-position lower limit adjustment unit 39B, the M-position upper limit adder 40U, the M-position lower limit adder 40B, the T-position upper limit adder 41U, the T-position lower limit adder 41B, the M-position output unit 50, and the T-position output unit 60.

[0026] The M-phase and T-phase filter units 32, 33 include, for example, a low-pass filter or a band-pass filter, and remove noise from the input M-phase and T-phase equivalent active power value (or active current value). The M-phase filter unit 32 outputs the M-phase equivalent active power value (or active current value) from which the noise has been removed to the subtractor 42 and the M-phase adder 43. The T-phase filter unit 33 outputs the T-phase equivalent active power value (or active current value) from which the noise has been removed to the subtractor 42 and the T-phase adder 44.

[0027] The subtractor 42 calculates a first power difference, which is a difference obtained by subtracting the T-phase equivalent active power value from the M-phase equivalent active power value. Alternatively, the subtractor 42 calculates a first current difference, which is a difference obtained by subtracting the T-phase equivalent active current value from the M-phase equivalent active current value. Then, the subtractor 42 outputs the first power difference or the first current difference to each of the M-phase compensation adjustment unit 34 and the T-phase compensation adjustment unit 35.

[0028] The M-phase compensation adjustment unit 34 applies a positive gain K nsp / 2 to calculate the second power difference or the second current difference, and output the second power difference or the second current difference to the M-coordinate adder 43. For example, nsp The value of is 10. The T compensation adjustment unit 35 applies a negative gain -K to the input first power difference or the first current difference. nsp / 2 to calculate a third power difference or a third current difference, and output the third power difference or the third current difference to the T-phase adder 44. The magnitude of the negative gain in the T-phase compensation adjustment unit 35 is the same as the magnitude of the positive gain in the M-phase compensation adjustment unit 34.

[0029] Therefore, when the M-phase equivalent active power value (or active current value) is greater than the T-phase equivalent active power value (or active current value), a positive value is input to the M-phase adder 43, and a negative value is input to the T-phase adder 44. When the T-phase equivalent active power value (or active current value) is greater than the M-phase equivalent active power value (or active current value), a negative value is input to the M-phase adder 43, and a positive value is input to the T-phase adder 44.

[0030] The M-coordinate adder 43 calculates an M-coordinate sum by adding the second power difference (or second current difference) output from the M-coordinate compensation adjustment unit 34 to the M-coordinate equivalent active power value (or active current value), and outputs the M-coordinate sum to each of the M-coordinate gain units 36U, 36B. The larger the M-coordinate equivalent active power value (or active current value), the larger the M-coordinate sum becomes. Also, the larger the second power difference (or second current difference), the larger the M-coordinate sum becomes.

[0031] The T-phase adder 44 calculates a T-phase added value by adding the third power difference (or third current difference) output from the T-phase compensation adjustment unit 35 to the T-phase equivalent active power value (or active current value), and outputs the T-phase added value to each of the T-phase gain units 37U and 37B. The T-phase added value becomes larger as the T-phase equivalent active power value (or active current value) becomes larger. Also, the T-phase added value becomes larger as the third power difference (or third current difference) becomes larger.

[0032] The M-coordinate gain unit 36U multiplies the input M-coordinate sum value by a preset gain to calculate a first M-coordinate multiplied value, and outputs the first M-coordinate multiplied value to the M-coordinate upper limit adjustment unit 38U. The M-coordinate gain unit 36B multiplies the input M-coordinate sum value by a preset gain to calculate a second M-coordinate multiplied value, and outputs the second M-coordinate multiplied value to the M-coordinate lower limit adjustment unit 38B. If the gain value of the M-coordinate gain unit 36B can be made common to the gain value of the M-coordinate gain unit 36U, one of the M-coordinate gain units 36U and 36B may be deleted. In that case, the first M-coordinate multiplied value becomes the same value as the second M-coordinate multiplied value.

[0033] The M-phase upper limit adjustment unit 38U outputs a first M-phase adjustment value for adjusting an M-phase upper limit voltage command value of a limiter unit 61, which will be described later, to the M-phase upper limit adder 40U, based on the input first M-phase multiplication value. The first M-phase adjustment value is set so that the M-phase upper limit voltage command value decreases in accordance with an increase in the M-phase equivalent active power value (or the M-phase equivalent active current value) supplied from the power transmission line 2 to the substation 22. In this embodiment, the first M-phase adjustment value is a value according to the first M-phase multiplication value, and is, for example, a value not less than -3.0 kV and not more than 0.0 kV.

[0034] The M coordinate upper limit adjustment unit 38U may input the 1M coordinate multiplication value into a prepared formula to calculate the 1M coordinate adjustment value. Alternatively, the M coordinate upper limit adjustment unit 38U may acquire the 1M coordinate adjustment value based on a 1M coordinate table and the 1M coordinate multiplication value. The 1M coordinate table indicates the correspondence between the 1M coordinate multiplication value and the 1M coordinate adjustment value. The 1M coordinate table is stored in the memory of the control device 360 ​​or a memory connected to the control device 360.

[0035] The M-phase lower limit adjustment unit 38B outputs a second M-phase adjustment value for adjusting an M-phase lower limit voltage command value of a limiter unit 61, which will be described later, to the M-phase lower limit adder 40B, based on the input second M-phase multiplication value. The second M-phase adjustment value is set so that the M-phase lower limit voltage command value of the limiter unit 61 increases in accordance with an increase in the M-phase equivalent active power value (or the M-phase equivalent active current value) supplied from the power transmission line 2 to the substation 22. The second M-phase adjustment value is a value according to the second M-phase multiplication value, and is, for example, a value not less than 0.0 kV and not more than 3.0 kV.

[0036] The M coordinate lower limit adjustment unit 38B may input the 2M coordinate multiplication value into a prepared formula to calculate the 2M coordinate adjustment value. Alternatively, the M coordinate lower limit adjustment unit 38B may acquire the 2M coordinate adjustment value based on a 2M coordinate table and the 2M coordinate multiplication value. The 2M coordinate table indicates the correspondence between the 2M coordinate multiplication value and the 2M coordinate adjustment value. The 2M coordinate table is stored in the memory of the control device 360 ​​or a memory connected to the control device 360.

[0037] The M-phase upper limit adder 40U adds a preset upper limit setting value to the input first M-phase adjustment value to calculate an M-phase upper limit voltage command value. The M-phase upper limit adder 40U outputs the calculated M-phase upper limit voltage command value to the M-phase output unit 50. For example, the upper limit setting value is 80.0 kV.

[0038] The M-phase lower limit adder 40B adds a preset lower limit setting value to the input second M-phase adjustment value to calculate an M-phase lower limit voltage command value. The M-phase lower limit adder 40B outputs the calculated M-phase lower limit voltage command value to the M-phase output unit 50. For example, the lower limit setting value is 77.0 kV.

[0039] The M-phase output unit 50 acquires the effective value of the M-phase equivalent voltage at the connection point PP in addition to the M-phase upper limit voltage command value and the M-phase lower limit voltage command value. The M-phase output unit 50 calculates an M-phase equivalent output command value for the three-phase power conversion system 30 based on the M-phase upper limit voltage command value, the M-phase lower limit voltage command value, and the effective value of the M-phase equivalent voltage. The configuration of the M-phase output unit 50 is similar to the configuration of the T-phase output unit 60 described later, so details will be omitted.

[0040] The T-axis gain unit 37U, like the M-axis gain unit 36U, multiplies the input T-axis addition value by a preset gain to calculate a first T-axis multiplication value, and outputs the first T-axis multiplication value to the T-axis upper limit adjustment unit 39U. The T-axis gain unit 37B, like the M-axis gain unit 36B, multiplies the input T-axis addition value by a preset gain to calculate a second T-axis multiplication value, and outputs the second T-axis multiplication value to the T-axis lower limit adjustment unit 39B. If the gain value of the T-axis gain unit 37B can be made common to the gain value of the T-axis gain unit 37U, either the T-axis gain unit 37U or the T-axis gain unit 37B may be deleted. In that case, the first T-axis multiplication value becomes the same value as the second T-axis multiplication value.

[0041] The T-phase upper limit adjustment unit 39U, like the M-phase upper limit adjustment unit 38U, outputs a first T-phase adjustment value for adjusting the T-phase upper limit voltage command value of the limiter unit 61 to the T-phase upper limit adder 41U based on the input first T-phase multiplication value. The first T-phase adjustment value is set so that the T-phase upper limit voltage command value decreases according to an increase in the T-phase equivalent active power value (or the T-phase equivalent active current value) supplied from the power transmission line 2 to the substation 22. In this embodiment, the first T-phase adjustment value is a value according to the first T-phase multiplication value, and is, for example, a value of -3.0 kV or more and 0.0 kV or less.

[0042] The T-phase lower limit adjustment unit 39B, like the M-phase lower limit adjustment unit 38B, outputs a second T-phase adjustment value for adjusting a T-phase lower limit voltage command value of a limiter unit 61 (to be described later) to the T-phase lower limit adder 41B based on the input second T-phase multiplication value. The second T-phase adjustment value is set so that the T-phase lower limit voltage command value of the limiter unit 61 increases according to an increase in the T-phase equivalent active power value (or the T-phase equivalent active current value) supplied from the power transmission line 2 to the substation 22. The second T-phase adjustment value is a value according to the second T-phase multiplication value, and is, for example, a value of 0.0 kV or more and 3.0 kV or less.

[0043] The T-phase upper limit adder 41U, like the M-phase upper limit adder 40U, adds a preset upper limit setting value to the input first T-phase adjustment value to calculate a T-phase upper limit voltage command value. The T-phase upper limit adder 40U outputs the calculated T-phase upper limit voltage command value to the T-phase output unit 60. For example, the upper limit setting value is 80.0 kV.

[0044] The T-phase lower limit adder 41B, like the M-phase lower limit adder 40B, adds a preset lower limit setting value to the input second T-phase adjustment value to calculate a T-phase lower limit voltage command value. The T-phase lower limit adder 41B outputs the calculated T-phase lower limit voltage command value to the T-phase output unit 60. For example, the lower limit setting value is 77.0 kV.

[0045] The T output unit 60 includes a limiter unit 61, a subtractor 62, an automatic voltage adjustment unit 63, and a fixed power factor control unit 64. Although omitted in Fig. 2, the M output unit 50 also includes a limiter unit 61, a subtractor 62, an automatic voltage adjustment unit 63, and a fixed power factor control unit 64, similar to the T output unit 60. Below, the T output unit 60 will be described, but the description of the T output unit 60 also applies to the M output unit 50.

[0046] The limiter unit 61 obtains the effective value of the T switch equivalent voltage at the connection point PP in addition to the T switch upper limit voltage command value and the T switch lower limit voltage command value. The limiter unit 61 outputs a value equal to or greater than the T switch lower limit voltage command value and equal to or less than the T switch upper limit voltage command value based on the effective value of the T switch equivalent voltage. That is, when the effective value of the T switch equivalent voltage is less than the T switch lower limit voltage command value, the limiter unit 61 outputs the T switch lower limit voltage command value. When the effective value of the T switch equivalent voltage is greater than the T switch upper limit voltage command value, the limiter unit 61 outputs the T switch upper limit voltage command value. When the effective value of the T switch equivalent voltage is equal to or greater than the T switch lower limit voltage command value and equal to or less than the T switch upper limit voltage command value, the limiter unit 61 outputs the effective value of the T switch equivalent voltage.

[0047] The subtractor 62 calculates a voltage difference by subtracting the effective value of the T-phase equivalent voltage at the connection point PP from the output value of the limiter unit 61 , and outputs the calculated voltage difference to the automatic voltage adjustment unit 63 . The automatic voltage adjustment unit 63 calculates a Tesla equivalent output command value of the three-phase power conversion system 30 so that the effective value of the Tesla equivalent voltage output from the three-phase power conversion system 30 follows the difference input from the subtractor 62, and outputs the calculated value to the fixed power factor control unit 64. That is, the automatic voltage adjustment unit 63 calculates a Tesla equivalent output command value of the three-phase power conversion system 30 so that the effective value of the Tesla equivalent voltage at the connection point PP is equal to or greater than the Tesla lower limit voltage command value and equal to or less than the Tesla upper limit voltage command value. The automatic voltage adjustment unit 63 executes proportional-integral control with a slope, for example. The Tesla equivalent output command value calculated by the automatic voltage adjustment unit 63 is, for example, an output command value of the Tesla equivalent apparent power.

[0048] The fixed power factor control unit 64 calculates a T-position equivalent output command value of the three-phase power conversion system 30 based on the output value of the automatic voltage adjustment unit 63. The fixed power factor control unit 64 calculates a T-position equivalent output command value of the three-phase power conversion system 30 (specifically, an active power output command value and a reactive power output command value equivalent to the T-position) so that the power factor of the output power equivalent to the T-position of the three-phase power conversion system 30 becomes a preset value.

[0049] The control device 360 ​​converts the calculated M-phase equivalent output command value and T-phase equivalent output command value into three-phase output command values, and outputs the converted three-phase output command value to the inverter 340. As a result, when the M-phase equivalent active power output from the other power source of the power system 100 is larger than the T-phase equivalent active power, the M-phase equivalent active power output from the three-phase power conversion system 30 increases and the T-phase equivalent active power decreases. As a result, the M-phase equivalent active power output from the other power source of the power system 100 decreases and the T-phase equivalent active power increases. As a result, the three-phase unbalanced power of the power system 100 is suppressed, and the line voltage is suppressed.

[0050] Furthermore, when the Testo equivalent active power output from the other power sources of the power system 100 is greater than the M-phase equivalent active power, the Testo equivalent active power output from the three-phase power conversion system 30 increases and the M-phase equivalent active power decreases. As a result, the Testo equivalent active power output from the other power sources of the power system 100 decreases and the M-phase equivalent active power increases. As a result, the three-phase unbalanced power of the power system 100 is suppressed, and the line voltage is suppressed.

[0051] Fig. 3 shows the line voltage of the power system 100 to which the three-phase power conversion system 30 according to this embodiment is applied, and Fig. 4 shows the line voltage of the power system 100 to which the power conversion system according to Patent Document 2 is applied. The control device for the power conversion system according to Patent Document 2 does not include the subtractor 42, the M-phase compensation adjustment unit 34, and the T-phase compensation adjustment unit 35, as compared with the control device 360. That is, the control device for the power conversion system according to Patent Document 2 does not include a function for compensating for three-phase unbalanced power. Therefore, in Patent Document 2, the RS line voltage is excessive.

[0052] In contrast, in this embodiment, the RS line voltage is effectively suppressed. That is, in this embodiment, not only can the M-phase active power and the T-phase active power for the power system 100 be individually optimized, but also the three-phase unbalanced power in the entire power system 100 can be suppressed.

[0053] Furthermore, by applying the three-phase power conversion system 30 to the power grid 100, it is possible to expand the power transmission range while avoiding the need to increase other power sources and power transmission lines. Furthermore, the control device 360 ​​increases the M-phase lower limit voltage command value and the T-phase lower limit voltage command value of the limiter unit 61 in response to an increase in the train load in the power system 100, so that a part of the power supplied from the transmission line 2 to the substation 22 is output from the three-phase power conversion system 30. This makes it possible to suppress an increase in the load on the power source PS when the train load in the power system 100 increases.

[0054] Furthermore, the control device 360 ​​reduces the M-phase upper limit voltage command value and the T-phase upper limit voltage command value of the limiter unit 61 in response to an increase in the train load in the power system 100. This makes it possible to suppress the fluctuation range of the voltage at the connection point PP regardless of the magnitude of the train load. In other words, it is possible to suppress the voltage at the connection point PP from becoming excessive, and to suppress the reverse power flow from the three-phase power conversion system 30.

[0055] Therefore, by applying the three-phase power conversion system 30 to the power system 100, the transmission range can be expanded while avoiding the need to increase other power sources and transmission lines in the power system 100. In addition, when the train load increases, it is possible to suppress the voltage fluctuation in the power system 100 while suppressing an increase in the burden on other power sources, and further suppress the line voltage and phase voltage. [Explanation of symbols]

[0056] 1-4...transmission lines, 21-24...substations, 30...three-phase power conversion system, 34...M-slot compensation adjustment unit, 35...T-slot compensation adjustment unit, 38U...M-slot upper limit adjustment unit, 38B...M-slot lower limit adjustment unit, 39U...T-slot upper limit adjustment unit, 39B...T-slot lower limit adjustment unit, 50...M-slot output unit, 60...T-slot output unit, 61...limiter unit, 63...automatic voltage adjustment unit, 64...fixed power factor control unit, 100...power system, 360...control device.

Claims

1. A three-phase power conversion system applied to a power system that supplies power from a power source to a plurality of substations and train loads via a power transmission line, a first limiter unit that receives an effective value of a first voltage corresponding to a single-phase voltage of a first system at a connection point where the three-phase power conversion system is connected to the power transmission line, and outputs the input effective value of the first voltage as a value that is equal to or less than a first upper limit value and equal to or greater than a first lower limit value; a second limiter unit which receives an effective value of a second voltage corresponding to a single-phase voltage of a second system having a phase difference of 90 degrees with the first system at the connection point, and outputs the effective value of the second voltage as a value not greater than a second upper limit value and not less than a second lower limit value; a first automatic voltage regulator and a first fixed power factor controller that calculate a first output command value for the three-phase power conversion system based on a voltage difference obtained by subtracting an effective value of the first voltage from an output value of the first limiter, so that a power factor of output power becomes a predetermined value; a second automatic voltage regulator and a second fixed power factor controller that calculate a second output command value for the three-phase power conversion system based on a voltage difference obtained by subtracting an effective value of the second voltage from an output value of the second limiter, so that a power factor of the output power becomes the predetermined value; a first lower limit adjusting unit that adjusts the first lower limit value based on a first active power value equivalent to an active power value of the first system at a predetermined position of the power transmission line or a first active current value equivalent to an active current value of the first system, and further adjusts the first lower limit value based on a power difference between the first active power value and a second active power value equivalent to an active power value of the second system at the predetermined position or a current difference between the first active current value and a second active current value equivalent to the active current value of the second system at the predetermined position; a second lower limit adjusting unit that adjusts the second lower limit value based on the second active power value or the second active current value, and further adjusts the second lower limit value based on the power difference or the current difference. Three-phase power conversion system.

2. the first lower limit adjusting unit increases the first lower limit value in accordance with a magnitude of the power difference or the current difference when the first active power value is greater than the second active power value or when the first active current value is greater than the second active current value; the second lower limit adjusting unit reduces the second lower limit in accordance with a magnitude of the power difference or the current difference when the first active power value is greater than the second active power value or when the first active current value is greater than the second active current value.

2. The three-phase power conversion system of claim 1.

3. a first upper limit adjustment unit that adjusts the first upper limit value based on the first active power value or the first active current value; A second upper limit adjustment unit that adjusts the second upper limit value based on the second active power value or the second active current value.

3. A three-phase power conversion system according to claim 1 or 2.

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