JP2020029247A - Power conversion system, transportation system, and power conversion method - Google Patents

Abstract

To provide a power conversion system, a transportation system, and a power conversion method capable of effectively using regenerative electric power.SOLUTION: A power conversion system 1 includes: a transformer 100 for a rectifier for converting a voltage of received AC power; a rectifier 400 for converting AC power to DC power and outputting the DC power to a load side; and a voltage adjusting device 200 provided between the transformer 100 for a rectifier and the rectifier 400 for adjusting a voltage. The voltage adjusting device 200 is configured using an inductance-variable variable reactor, and changes a voltage drop rate of the AC power whose voltage is converted by the transformer 100 for a rectifier.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power conversion system, a transportation system, and a power conversion method.

Several techniques have been proposed for a power conversion system used for a DC feeding system in a transportation system such as an electric railway.
For example, Patent Literature 1 describes a rectifier voltage control technique and a parallel operation method that can cope with a feeder circuit having extremely small electric resistance such as a superconducting wire.

JP 2011-51558 A

  One of the issues in DC feeding is effective utilization of regenerative power. For example, when a substation is connected between a regenerative vehicle (vehicle performing regenerative braking) and a power running vehicle (vehicle performing power running) on a track, the voltage at the regenerative vehicle is higher than the voltage at the connection point of the substation. If it is low, regenerative power cannot be passed to the power train. In this case, the regenerative vehicle secures a braking force by mechanical braking or the like, and the regenerative electric power cannot be effectively used.

  The present invention provides a power conversion system, a transportation system, and a power conversion method that can effectively utilize regenerative power.

  According to the first aspect of the present invention, a power conversion system includes a transformer for converting a voltage of AC power to be received, a rectifier for converting AC power to DC power and outputting the DC power to a load side, and the transformer. A voltage regulator provided between the rectifier and the regulator.

  The voltage regulator may be configured using a variable reactor having a variable inductance, and the transformer may change a voltage drop rate of AC power obtained by converting the voltage.

  The voltage adjusting device may change the inductance by changing a magnetic flux in the iron core according to a change in a DC current amount flowing through a control winding wound around the iron core of the reactor.

  According to the second aspect of the present invention, the transportation system includes any one of the above-described power conversion systems, a power line and a return line that can be combined with the power conversion system, and configure an electric circuit; A vehicle that travels on the track by acquiring power from the power line.

  According to a third aspect of the present invention, a power conversion method includes converting a voltage of AC power to be received by a transformer, adjusting a voltage of AC power output from the transformer by a voltage regulator, and This includes converting the AC power output from the adjusting device into DC power by a rectifier and outputting the DC power to the load side.

  According to the present invention, the regenerative electric power can be effectively used.

1 is a schematic block diagram illustrating a functional configuration of a power conversion system according to an embodiment of the present invention. 1 is a diagram illustrating a configuration example of a power conversion system according to an embodiment of the present invention. It is a figure showing an example of a coil in a voltage regulation device of an embodiment of the present invention. 4 is a graph illustrating an example of a rectifier voltage drop by the voltage regulator according to the embodiment of the present invention. It is a figure showing the 1st example of composition different from the power conversion system of this embodiment in power conversion. 6 is a graph showing an example of a voltage drop due to the configuration shown in FIG. FIG. 6 is a diagram illustrating an example of a voltage distribution on a train line in the case of the configuration illustrated in FIG. 5. FIG. 3 is a diagram illustrating an example of a voltage distribution in a power line in the case of the configuration illustrated in FIG. 2 according to the embodiment of the present invention. It is a figure showing the 2nd example of composition different from the power conversion system of the embodiment of the present invention in power conversion. It is a figure showing the 3rd example of composition different from power conversion system of an embodiment of the present invention in power conversion. It is a figure showing the 4th example of composition different from power conversion system of an embodiment of the present invention in power conversion. It is a figure which shows the 5th example of a structure different from the power conversion system of embodiment of this invention in power conversion. 5 is a graph showing a first example of a simulation result of an operation of the power conversion system according to the embodiment of the present invention. 9 is a graph illustrating a second example of a simulation result of the operation of the power conversion system according to the embodiment of the present invention. 5 is a graph illustrating an example of a magnetization characteristic of a reactor core. It is a graph which shows the example of the relationship between the current which flows through the winding of a reactor, and inductance. It is a graph which shows the example of the relationship between the electric current which flows through the winding of a reactor, and a voltage drop rate.

Hereinafter, embodiments of the present invention will be described, but the following embodiments do not limit the invention according to the claims. In addition, not all combinations of the features described in the embodiments are necessarily essential to the solution of the invention.
FIG. 1 is a schematic block diagram illustrating a functional configuration of a power conversion system according to an embodiment of the present invention. As shown in FIG. 1, the power conversion system 1 includes a rectifier transformer 100, a voltage regulator 200, a controller 300, and a rectifier (diode rectifier) 400.

The power conversion system 1 is installed in a substation 800. The substation 800 includes, in addition to the power conversion system 1, an in-plant bus 810, a transformer circuit breaker 820, and a DC high-speed circuit breaker 830.
The station bus 810 is connected to the commercial power system 710 via the first power path W111. The first power path W111 is provided with a power receiving circuit breaker (power receiving switch) 720 and a transaction power meter (watt hour meter) 730. Rectifier 400 is connected to a train line 910 by a fifth power path W115. A DC high-speed circuit breaker 830 is provided in the fifth power path W115. In addition, rectifier 400 is connected to rail 920 by sixth power path W116.

The in-plant bus 810 and the rectifier transformer 100 are connected by a second power path W112, and a transformer breaker 820 is provided in the second power path W112. The rectifier transformer 100 and the voltage regulator 200 are connected by a third power path W113. The voltage regulator 200 and the rectifier 400 are connected by a fourth power path W114. The voltage regulator 200 and the controller 300 are connected by a control path W121.
The vehicle (electric vehicle) 930 is a traveling vehicle of a train, and travels on a track including a train line 910 and a rail 920.

The commercial power system 710 is a power system of a power company, and transmits extra-high voltage or high-voltage three-phase AC power such as, for example, 22 kilovolt (kV) three-phase AC power. A part of the power transmitted by the commercial power system 710 is diverted to the first power path W111 and supplied to the substation 800.
The power receiving circuit breaker 720 disconnects the substation 800 from the commercial power system 710 when a failure occurs.
The transaction power meter 730 measures the amount of supplied power for calculating the power rate for the power supplied from the commercial power system 710 to the substation 800.

The station bus 810 distributes the power supplied from the commercial power system 710 to the facilities in the 800 substations. For example, the in-house bus 810 is a transformer for high-voltage distribution provided to high-voltage distribution lines to which stations, signal communication facilities, machine rooms, and the like are connected, in addition to the rectifier transformer 100 of the power conversion system 1, and a control in the substation. Power is also distributed to transformers other than the rectifier transformer 100, such as a control transformer that supplies power. Regarding power supply to the power conversion system 1, part of the power received by the bus 810 from the commercial power system 710 is shunted to the second power path W <b> 112 and supplied to the rectifier transformer 100 of the power conversion system 1. .
Hereinafter, an example in which the in-house bus is a special high-voltage bus having a voltage exceeding 7 kV (for example, 22 kV, 33 kV, 66 kV, or 77 kV) will be described. Alternatively, the in-house bus may be configured as a high-voltage bus having a voltage of 7 kV or less (for example, 6.6 kV).
The transformer circuit breaker 820 disconnects the power conversion system 1 from the in-house bus 810 when a failure occurs.
Note that a disconnector may be provided in addition to the transformer circuit breaker 820 to be configured as a set of switches.

The power conversion system 1 steps down and rectifies the special high-voltage three-phase AC power supplied from the in-house bus 810, and supplies the obtained DC power to the train line 910 via the fifth power path W115. The DC high-speed circuit breaker 830 cuts off the power conversion system 1 from the electric line 910 when a failure occurs.
The combination of the power conversion system 1, the fifth power path W115, the DC high-speed circuit breaker 830, the train line 910, the rail 920, and the sixth power path W116 forms a feeding circuit. The return current flowing through rail 920 returns to rectifier 400 via sixth power path W116.

In the power conversion system 1, the rectifier transformer 100 steps down the supplied special high-voltage three-phase AC power. The power stepped down by the rectifier transformer 100 is input to the voltage regulator 200 via the third power path W113. The voltage adjustment device 200 adjusts and outputs the voltage of the input power according to the control of the control device 300. The control device 300 controls the voltage adjustment by the voltage adjustment device 200 by, for example, feedback control of the voltage target value and the voltage measurement value. The power whose voltage has been adjusted by the voltage adjustment device 200 is input to the rectifier 400 via the fourth power path W114. The rectifier 400 rectifies the input power and supplies the obtained DC power to the train line 910 via the fifth power path W115.
The control path W121 is a transmission path of a control signal from the control device 300 to the voltage adjustment device 200.

  Note that the combination of the power conversion system 1, the train line 910, the track 901 and the vehicle 930 corresponds to an example of a transportation system. In this transportation system, the power conversion system 1, the train line 910, and the track 901 can be combined to form an electric circuit, and power is supplied to the vehicle 930. Vehicle 930 receives electric power from electric power conversion system 1 from track 901 and electric line 910 and travels on track 901 (on rail 920). The track 901 corresponds to an example of a return track.

However, the transportation system to which the power conversion system 1 supplies power is not limited to the one using the track 901 as the return line. A return track may be provided separately from the track 901.
Further, the transportation system to which the power conversion system 1 supplies power is not limited to the one in which the rail 920 is provided on the track 901. For example, a guideway may be provided on the track 901. In this case, the guideway only needs to guide the traveling direction of the vehicle 930, and is not limited to a specific form. For example, the guideway may be configured as a side wall installed on both sides of the traveling area of the vehicle 930.

FIG. 2 is a diagram illustrating a configuration example of the power conversion system 1.
In the example shown in FIG. 2, a disconnector 821 is provided in the second power path W112 in addition to the transformer breaker 820. The transformer circuit breaker 820 has an arc extinguishing function, and can cut off the second power path W112 (release the circuit) while the second power path W112 is energized. On the other hand, the disconnecting switch 821 does not have the arc extinguishing function, and completely disconnects the second power path W112 from the commercial power system 710 by opening the contacts in a state where the second power path W112 is not energized. For separating electric circuits.

In the example of FIG. 2, the rectifier transformer 100 is configured using a three-phase three-winding transformer having an extra-high-voltage primary winding, a high-voltage secondary winding suitable for the rectifier 400, and a tertiary winding. Then, the special high-voltage three-phase AC power input to the rectifier transformer 100 is stepped down and converted into six-phase AC power (a combination of two three-phase ACs having a phase difference of 30 degrees).
In the example of FIG. 2, the third power path W113 is configured using, for example, two sets of three-phase bus ducts (Bus Duct) and two sets of three-phase high-voltage cables, and outputs the six-phase AC power output from the rectifier transformer 100. Is supplied to the voltage regulator 200. The third power path W113 branches to the control device 300, and supplies a part of the power output from the rectifier transformer 100 to the control device 300.

  In the example of FIG. 2, the voltage adjustment device 200 is configured as a reactor in which a control winding and a main winding are wound around an iron core. Hereinafter, a reactor in which a control winding and a main winding are wound around an iron core is referred to as a magnetic flux control type variable reactor. In the magnetic flux control type variable reactor, the characteristics of the reactor change when a direct current flows through the control winding. In particular, in the magnetic flux control type variable reactor, the leakage reactance changes according to the current flowing through the control winding, and the magnitude of the voltage drop in the output power changes. Here, the voltage drop is a decrease in the output voltage in accordance with an increase in the current.

FIG. 3 is a diagram illustrating an example of a winding in the voltage adjustment device 200.
In the example of FIG. 3, for example, a control winding 202 is wound around an iron core 201, and a main winding 203 is further wound therearound.
When a current flows through the control winding 202, the leakage reactance changes, and the voltage drop in the output voltage changes.
The power conversion system 1 may be provided with two voltage regulators 200 for each of three phases to support six-phase alternating current. Alternatively, the power conversion system 1 may include one voltage regulator 200 corresponding to six phases.

FIG. 4 is a graph showing an example of a voltage drop in the output power of rectifier 400. When the output power of the voltage regulator 200 drops, the output power of the rectifier 400 also drops.
The horizontal axis of the graph of FIG. 4 indicates the output current of the rectifier 400. The vertical axis indicates the output voltage of the rectifier 400. The current I11 indicates a rated current.
Lines L11, L12, and L13 indicate the relationship between the output current and output voltage of rectifier 400, respectively. The slope of each of the lines L11, L12, and L13 indicates a voltage drop. The larger the current flowing through the control winding 202, the smaller the voltage drop.

In the example of FIG. 2, the control device 300 is configured using an AC / DC converter, converts an AC current (AC power) supplied from the rectifier transformer 100 into a DC current, and controls the voltage control device 200. The current flowing through the line is supplied to the voltage regulator 200 via the control path W121. This current corresponds to an example of a control signal for the control device 300 to control the voltage adjustment device 200. The control device 300 may be configured to acquire power from an in-house bus 810 or a low-voltage substation power supply or the like.
Control device 300 can adjust the magnitude of the output direct current. Control device 300 performs feedback control of the output voltage of power conversion system 1 by adjusting the magnitude of the current flowing through the control winding based on, for example, the deviation between the measured value of the output voltage from rectifier 400 and the voltage target value. I do.

In the example of FIG. 2, the fourth power path W114 is configured using, for example, a bus duct or a high-voltage cable like the third power path W113, and supplies the rectifier 400 with the six-phase AC power output from the voltage regulator 200. .
In the example of FIG. 2, the rectifier 400 is configured using a full-wave rectifier circuit using a diode bridge, and converts six-phase AC power supplied from the voltage regulator 200 into DC power and outputs the DC power. In the rectifier 400, by rectifying the six-phase AC power with a diode bridge, DC power having 12 ripples during one AC cycle can be obtained. By smoothing the DC power having the ripple, a DC current having a relatively small ripple is supplied to the vehicle 930.
As described with reference to FIG. 1, the fifth power path W <b> 115 supplies the DC current output from the rectifier 400 to the train line 910. Sixth power path W116 returns the return current flowing through rail 920 to rectifier 400. This ripple is smoothed by a filter facility (not shown) placed in the substation, the inductance and capacitance of the train line 910 and the rail 920, the input reactor of the vehicle 930, and the like.

Here, for comparison with the power conversion system 1, power conversion using a configuration different from that of the power conversion system 1 will be described.
FIG. 5 is a diagram illustrating a first example of a configuration different from the power conversion system 1 in power conversion. 5, the same reference numerals (100, 400, 710, 820, 821) are assigned to parts having the same functions corresponding to the respective parts of the configuration in FIG. 2, and the description is omitted.

The example of FIG. 5 differs from the example of FIG. 2 in that the voltage regulator 200 and the controller 300 are not provided, and the rectifier transformer 100 and the rectifier 400 are directly connected. Due to such a difference, in the example of FIG. 5, the voltage is not adjusted, and the voltage on the electric line 910 is determined by conditions such as the supply state of the commercial power and the state of the vehicle 930 as a load.
Hereinafter, the substation having the configuration in FIG. 5 is referred to as a substation 1001. The configuration of the substation 1001 is currently the most common configuration for a substation for DC electric railway.

FIG. 6 is a graph showing an example of a voltage drop due to the configuration shown in FIG. The horizontal axis of the graph in FIG. 6 indicates the output current from the rectifier 400. The vertical axis indicates the output voltage from rectifier 400.
Line L21 indicates the relationship between the output current from rectifier 400 and the output voltage. The current I11 indicates a rated current. The voltage V11 indicates a rated voltage. In the configuration shown in FIG. 5, the output voltage becomes the rated voltage when the rated current is output. This characteristic is uniquely determined by the voltage of the in-house bus 810, the rating of the rectifier transformer 100, the voltage fluctuation rate, and the tap, and cannot be dynamically changed.

FIG. 7 is a diagram illustrating an example of a voltage distribution on the electric line 910 in the case of the configuration illustrated in FIG. 5.
In the example of FIG. 7, three substations 1001 that supply electric power to the train line 910 are arranged. These substations 1001 are distinguished by reference numerals 1001a, 1001b and 1001c. Further, in the example of FIG. 7, two vehicles 930 are shown. These vehicles 930 are distinguished by attaching reference numerals 930a and 930b.

FIG. 7 is a graph showing a voltage distribution and a current distribution in the electric train line 910. The horizontal axis of the graph of the voltage distribution indicates a position in a track including the electric line 910 and the rail 920. The vertical axis indicates the voltage on the train line 910. The voltage on the train line 910 is referred to as a feeding voltage. Voltage V11 indicates the output voltage of rectifier 400 of substation 1001. Line L31 indicates the voltage for each position on the trajectory. The line L32 indicates the current for each position on the trajectory.
The horizontal axis of the graph of the current distribution indicates a position on a track including the electric line 910 and the rail 920. The vertical axis indicates the current in the train line 910. The current in the trolley line 910 is called a feeding current.

The substations 1001a, 1001b, and 1001c have different output currents flowing through the trolley line 910, and the output voltages of the respective rectifiers 400 are different. However, this difference is sufficiently smaller than the voltage drop at the trolley line 910 and the rail 920. Therefore, the positions where the substations 1001a, 1001b, and 1001c are connected to the train line 910 are all shown as the same voltage V11.
The vehicle 930a is a regenerative vehicle, and the vehicle 930b is a power running vehicle. The regenerative vehicle referred to here is the vehicle 930 that is braking by the regenerative brake. The power running vehicle is a vehicle 930 that is running. The vehicle 930a emits regenerative power to the train line 910. As a result, the voltage of the electric line 910 increases at the position of the vehicle 930a. In addition, the vehicle 930b has obtained electric power from the train line 910, and the voltage of the train line 910 has dropped at the position of the vehicle 930b.

As shown in the current distribution graph, both the regenerative current from the vehicle 930a and the current from the substation 1001b flow to the vehicle 930b. However, since the upper limit value of the output voltage at the time of regeneration of the vehicle 930 is determined, the difference between the voltage at the position of the vehicle 930a and the voltage at the position where the substation 1001b is connected cannot be made larger than a certain value. The regenerative current from the vehicle 930a does not flow much, and most of the current to the vehicle 930b is supplied from the substation 1001b.
It is preferable to improve the tide flow of the regenerative power flowing from the vehicle 930a to the vehicle 930b from the viewpoint of effective use of the regenerative power.

FIG. 8 is a diagram showing an example of a voltage distribution on the electric line 910 in the case of the configuration shown in FIG.
In the example of FIG. 8, three substations 800 that supply electric power to the train line 910 are arranged. These substations 800 are distinguished by reference numerals 800a, 800b and 800c. Also, the two vehicles 930 shown in FIG. 7 are distinguished by the same reference numerals 930a and 930b as in the case of FIG. As in the case of FIG. 7, the vehicle 930a is a regenerative vehicle, and the vehicle 930b is a power running vehicle.

Also, in FIG. 8, similarly to the case of FIG. 7, a voltage distribution and a current distribution on the electric line 910 are shown by a graph. The horizontal axis and the vertical axis of the graph are the same as those in FIG. A line L41 indicates a voltage for each position on the trajectory. The line L42 indicates the current at each position on the trajectory.
The voltages at the positions where the substations 800a and 800c are connected to the train line 910 have the same value. On the other hand, unlike the case of FIG. 7, the voltage at the position where the substation 800b is connected to the train line 910 is lower than these.

  This voltage distribution is provided by controlling the voltage drop rate shown in FIG. In the substations 800a and 800c, the control device 300 controls the voltage regulator 200 using, for example, a rated voltage as a target voltage value. As a result, in the substations 800a and 800c, the rated voltage is output from the rectifier 400 in a region where the output current is equal to or more than a certain value.

  On the other hand, in the substation 800b, the control device 300 controls the voltage regulator 200 by setting the target voltage value lower than that of the substations 800a and 800c. As a result, in the substation 800b, a voltage lower than the rated voltage is output from the rectifier 400 in a region where the output current is equal to or more than a certain value.

  As shown in the current distribution graph, both the regenerative current from the vehicle 930a and the current from the substation 1001b flow to the vehicle 930b. Further, since the voltage at the position where the substation 800b is connected is lower than the rated voltage, the difference between the voltage at the position of the vehicle 930a and the voltage at the position where the substation 800b is connected is shown in FIG. It is larger than in the case of the example. Thus, the regenerative current flowing from vehicle 930a to vehicle 930b is larger than in the case of FIG. In this regard, in the example of FIG. 8, the regenerative power can be used more effectively than in the case of FIG.

For example, the control device 300 acquires position information and load information of the vehicle 930 via an operation management system, a power management system, or the like. Then, the control device 300 crosses the connection position where the substation 800 including the control device 300 itself is connected to the train line 910 from the positional relationship between the regenerative vehicle 930a and the power running vehicle 930b as in the example of FIG. It is determined whether it is necessary to supply a regenerative current.
When it is determined that there is no need to supply a regenerative current across the connection position of the substation 800 including the control device 300 to the train line 910, the control device 300 sets the voltage at this connection position to, for example, the rated voltage. The control allows the vehicle 930 to run stably.
On the other hand, when it is determined that the regenerative current needs to flow across the connection position of the substation 800 including the control device 300 itself to the train line 910, the control device 300 performs control to reduce the voltage at this connection position. This facilitates the flow of the regenerative current.

The configuration for controlling the output voltage of the substation can be considered other than the configurations shown in FIGS. Here, in order to explain the effect obtained by the configuration shown in FIG. 2, another configuration and its problems will be described.
FIG. 9 is a diagram illustrating a second example of a configuration different from the power conversion system 1 in power conversion. 9, the same reference numerals (100, 400, 710, 820, and 821) are given to portions having the same functions corresponding to the respective portions of the configuration in FIG. 2, and description thereof will be omitted.

In the example of FIG. 9, a reactive power compensator 1012 is provided for the internal bus 810 in parallel with the configuration illustrated in FIG. 5. Between the in-house bus 810 and the reactive power compensator 1012, a transformer circuit breaker 820 and a disconnector 821 having the same configuration as that of FIG. 5 and a switch for controlling the magnitude of the reactive power (for example, a semiconductor device). (Composed of a bidirectional switch or an AC circuit breaker) 1011.
The reactive power compensator 1012 can directly control the bus voltage by consuming or supplying the reactive power of the local bus 810.

In the configuration shown in FIG. 9, the reactive power compensator 1012 is provided on an in-house bus 810 which is a special high-voltage bus having a large short-circuit capacity such as 22 kilovolts. A large-sized reactor or capacitor suitable for the insulation performance corresponding to such extra high voltage and a large short-circuit capacity is required, and the reactive power compensator 1012 becomes a large-sized device, requiring a manufacturing cost and an installation space.
On the other hand, in the configuration of FIG. 2, since the voltage regulator 200 receives the input of the high-voltage power reduced by the rectifier transformer 100, the voltage regulator 200 can be a device having a slight insulation performance as compared with the extra-high-voltage device. Further, a minimum necessary capacity corresponding to the capacity of the rectifier 400 is sufficient. In these respects, the manufacturing cost of the voltage adjustment device 200 can be relatively reduced, and the installation space for the voltage adjustment device 200 can be relatively small.

FIG. 10 is a diagram illustrating a third example of a configuration different from the power conversion system 1 in power conversion. 10, the same reference numerals (100, 400, 710, 820, 821) are assigned to parts having the same functions corresponding to the respective parts of the configuration in FIG.
In the example of FIG. 10, a load tap changer 1021 is provided between the rectifier transformer 100 and the transformer circuit breaker 820 in addition to the configuration shown in FIG. The on-load tap changer 1021 is operable even when the rectifier transformer 100 is energized, and the output voltage of the rectifier 400 is stepwise changed by switching the transformation ratio of the rectifier transformer 100 by the operation of the on-load tap changer 1021. Can be controlled.

The tap changer under load is generally slow in control (on the order of several seconds), and is not suitable for switching the output voltage to the train line 910 in accordance with the operation of the train. Further, since the tap changer under load has a life of about 200,000 operations, it is preferable to limit the switching to, for example, about 10 times a day assuming that the expected life of the equipment is 30 years. Also in this regard, the configuration of FIG. 10 using the on-load tap changer is not suitable for use in switching the output voltage to the train line 910 according to the operation of the train. Furthermore, when a load tap changer is applied, the transformer 100 for a rectifier needs to have a special specification applicable to this, and the load tap changer 1021 itself is also a large switch because it is a special high-voltage switch.
On the other hand, in the configuration of FIG. 2, the output voltage can be changed by changing the control current flowing through the voltage regulator 200. In the configuration of FIG. 2, high-speed and continuous voltage adjustment is possible because there is no need to perform mechanical switching, and there is no restriction on the number of voltage adjustments because semiconductor power conversion is used. In addition, the voltage regulator 200 can use a general-purpose rectifier transformer, and does not require additional special high-voltage equipment, so that the overall device size can be relatively small.

FIG. 11 is a diagram illustrating a fourth example of a configuration different from the power conversion system 1 in power conversion. 11, the same reference numerals (100, 400, 710, 820, and 821) are assigned to parts having the same functions corresponding to the respective parts of the configuration in FIG.
In the example of FIG. 11, in addition to the configuration shown in FIG. 5, a rectifier transformer 100 and a self-excited rectifier (configured with a thyristor rectifier) 1031 are provided in parallel with the configuration of FIG. I have. A transformer breaker 820 and a disconnector 821 are provided between the rectifier transformer 100 and the self-excited rectifier 1031 and the in-house bus 810, as in the configuration of FIG.

The rectifier 400 and the DC output of the self-excited rectifier 1031 are connected in series, and the voltage obtained by adding the output voltage of the rectifier 400 and the output voltage of the self-excited rectifier 1031 is supplied to the train line 910.
On the output side of the rectifier 400 and the self-excited rectifier 1031, a bypass disconnector 1032, a reactor 1033, and a smoothing capacitor 1034 are provided. In an application using a thyristor rectifier, the reactor 1033 and the smoothing capacitor 1034 may be omitted.
With such a configuration, the output voltage to the train line 910 can be controlled by the firing angle control of the thyristor in the self-excited rectifier 1031 or the PWM control (Pulse Width Modulation Control) of the self-excited element.

The configuration of FIG. 11 requires a plurality of rectifier transformers 100, which increases the manufacturing cost and the installation space. Further, in the configuration of FIG. 11, since the full load current always flows through the compensating circuit element, the size of the element increases and the conduction loss increases. Further, a large element is required which has a withstand capacity corresponding to a fault current of up to about 50 kiloamps (kA) which flows when a short circuit fault occurs in the train line 910.
On the other hand, in the configuration of FIG. 2, only one rectifier transformer 100 is required. In this respect, the manufacturing cost is low and the installation space is small. Further, in the configuration of FIG. 2, a semiconductor element is not necessary for the main circuit connected to the trolley line 910, and the semiconductor element is provided in the low-voltage circuit connected to the control winding of the variable reactor 200. It is possible to avoid an increase in power consumption and power loss. Furthermore, in the variable reactor 200, the main winding and the control winding are electromagnetically orthogonal to each other, and the effect of the short-circuit current supply on the electric line 910 does not appear on the control winding. Can be.

FIG. 12 is a diagram illustrating a fifth example of a configuration different from the power conversion system 1 in power conversion. 12, the same reference numerals (100, 710, 820, 821, 1031, 1033, and 1034) denote parts having the same functions corresponding to the respective parts of the configuration in FIG. Is omitted.
Compared with the configuration of FIG. 11, the configuration of FIG. 12 does not include the rectifier transformer 100 and the rectifier 400, and the rectifier transformer 100 and the self-excited rectifier 1031 perform the full power conversion required for the train line 910. .

In the configuration of FIG. 12, the rectifier transformer 100 has a special specification (the general-purpose product of FIG. 5 cannot be applied), and the self-excited rectifier 1031 requires a large-sized element corresponding to the required total power conversion. Therefore, the manufacturing cost is orders of magnitude higher than the configuration of FIG. Also, since the generated harmonics increase, the size of the filter equipment (reactor 1033, smoothing capacitor 1034, and additional compensator) increases, which also causes an increase in manufacturing cost.
On the other hand, in the configuration of FIG. 2, a general-purpose product can be applied to the rectifier transformer 100, and switching is not performed in the main circuit connected to the trolley line 910, so that the filter equipment is greatly simplified ( Can be omitted depending on the conditions), and the manufacturing cost can be greatly reduced.

As described above, the rectifier transformer 100 converts the voltage of the received AC power. Rectifier 400 converts AC power to DC power and outputs the DC power to the load side. In the case of FIG. 1, the vehicle 930 performing power running corresponds to an example of the load. The voltage regulator 200 is provided between the rectifier transformer 100 and the rectifier 400 to regulate the voltage.
Thereby, in the power conversion system 1, the output voltage from the power conversion system 1 can be controlled. By adjusting the voltage distribution in the power line by controlling the output voltage, the regenerative power from the regenerative vehicle can easily flow to the powering vehicle as described with reference to FIG. In this regard, according to the power conversion system 1, effective use of regenerative power can be achieved.
Further, according to the power conversion system 1, it is possible to compensate for a decrease in the supply voltage to the train line equipment and the vehicle due to the electric resistance.
Further, according to the power conversion system 1, it is possible to control the share of power consumption among a plurality of substations.

Further, the voltage adjustment device 200 is configured using a variable reactor having a variable inductance. The voltage regulator 200 changes the voltage drop rate of the AC power converted by the rectifier transformer 100.
The power conversion system 1 does not need to perform voltage control by switching by controlling the output voltage using the variable reactor. The power conversion system 1 does not require a large-capacity switching element, and in this regard, the manufacturing cost is low, and no harmonics are generated by power switching.
Further, according to power conversion system 1, any DC voltage within the rated range of voltage regulator 200 can be supplied to the DC feeding circuit without being restricted by the voltage drop characteristics of rectifier 400.

Further, voltage regulator 200 changes the magnetic flux in accordance with the change in the amount of DC current flowing through the control winding wound on the iron core of the reactor to change the inductance.
In the power conversion system 1, the fluctuation rate of the output voltage can be controlled by controlling the amount of current flowing through the control winding, and there is no need to perform voltage control by a mechanical mechanism such as a tap changer. In the power conversion system 1, voltage control can be performed at higher speed and continuously than in the case where voltage control is performed mechanically. For example, in the power conversion system 1, voltage control can be performed at a high speed with a time constant of less than 1 second.
Further, in the power conversion system 1, there is no limitation on the number of times of switching as in the case of performing voltage control mechanically.

Next, a simulation result of the operation of the power conversion system 1 will be described with reference to FIGS.
FIG. 13 is a graph illustrating a first example of a simulation result of the operation of the power conversion system 1. FIG. 13 shows a simulation result of a device having a relatively small capacity in which the rating of the rectifier 400 is about 750 kilowatts (kW). The horizontal axis of the graph in FIG. 13 indicates the output current from the power conversion system 1. The vertical axis indicates the output voltage from the power conversion system 1.

A line L51 indicates a relationship between the output current and the output voltage when the control current is 0 amps (A). Line L52 shows the relationship between the output current and the output voltage when the control current is 50 amps. Line L53 shows the relationship between the output current and the output voltage when the control current is 100 amps.
From the simulation results shown in FIG. 13, it was confirmed that the voltage drop rate (the ratio of the output voltage change to the output current change) changes according to the control current.

FIG. 14 is a graph illustrating a second example of a simulation result of the operation of the power conversion system 1. FIG. 14 shows a simulation result when the rectifier 400 is rated at 6000 kilowatts (kW), which is the largest capacity among the rectifiers 400 currently used. The horizontal axis of the graph in FIG. 14 indicates the output current from the power conversion system 1. The vertical axis indicates the output voltage from the power conversion system 1.
A line L61 indicates a relationship between the output current and the output voltage when the control current is 0 amps (A). Line L62 shows the relationship between the output current and the output voltage when the control current is 50 amps. Line L63 shows the relationship between the output current and the output voltage when the control current is 100 amps. A line L64 indicates the relationship between the output current and the output voltage when the rectifier transformer 100 and the rectifier 400 are directly connected as in the configuration of FIG. 5 without providing the voltage regulator 200.
From the simulation results shown in FIG. 14, it was confirmed that the voltage drop rate changes according to the control current even for the rating of 6000 kW.

Next, with reference to FIGS. 15 to 17, a difference between a usage of a general reactor and a usage of the reactor in the power conversion system 1 will be described. When a general usage of the reactor and a usage of the reactor in the power conversion system 1 are compared, the concept of the saturation region of the magnetization characteristic is completely different.
FIG. 15 is a graph showing an example of the magnetization characteristics of the iron core of the reactor. The horizontal axis of the graph in FIG. 15 indicates the magnetic field strength H. The vertical axis indicates the magnetic flux density B. The line of the graph in FIG. 15 shows an example of the magnetic hysteresis curve of the iron core.

A region A12 in FIG. 15 is a magnetically unsaturated region of the iron core, and shows magnetization characteristics of hysteresis. On the other hand, the regions A11 and A13 are both magnetic saturation regions of the iron core, and almost no hysteresis is observed in these regions.
In the case of general reactor usage, operation in the non-saturation region is a rule in order to reduce iron loss and noise, and the saturation region is a region in an abnormal state such as overload or overvoltage.

FIG. 16 is a graph showing an example of the relationship between the current flowing through the reactor winding and the inductance. This graph shows not only the power conversion system 1 but also the properties that can be realized by a general iron core reactor. The horizontal axis of the graph in FIG. 16 indicates the current (current value). The vertical axis indicates the inductance. The area A21 corresponds to an unsaturated area. The region A22 corresponds to a saturation region.
Line L71 shows the relationship between the current flowing through the winding and the inductance. In a region A21 corresponding to the non-saturation region, a relatively large inductance having a constant value does not depend on the current. On the other hand, in a region A22 corresponding to the saturation region, the inductance decreases as the current increases. In the region A21, the magnetization characteristics of the iron core are non-linear characteristics having hysteresis. However, when only the relationship between the amplitudes of H and B (corresponding to the relationship between the amplitudes of the current and the voltage) is evaluated, the relationship is almost linear. Is sometimes called a linear region.
In general usage of a reactor, it is important to obtain a stable inductance value, and a saturation region where the inductance decreases as the current increases is regarded as a region outside a normal use range.
On the other hand, in the usage of the reactor in the power conversion system 1, the magnitude of the voltage drop of the output voltage (the voltage across the reactor) is important, and the value of the inductance itself is not important.

FIG. 17 is a graph showing an example of the relationship between the current flowing through the winding of the reactor and the voltage drop (induced electromotive force) for the same reactor as in FIG. The horizontal axis of the graph in FIG. 17 indicates the current (current value). The vertical axis shows the voltage drop that occurs between the terminals of the reactor. The region A31 is a linear region corresponding to a non-saturation region and in which a voltage drop proportional to a current occurs. The region A32 corresponds to a saturation region.
Line L81 shows the relationship between the current flowing through the winding and the voltage drop.

In the region A32 corresponding to the saturation region, a constant voltage drop is obtained regardless of the magnitude of the current. In the power conversion system 1, since a stable voltage control width can be secured for a wide load from a light load region to a heavy load region, control of the voltage drop rate using the unsaturated region in the region A31 (see FIG. 4) It is more appropriate to control the voltage drop itself using the saturation region of the region A32 than to (concept).
In the saturation region, a substantially constant voltage drop is obtained irrespective of the current. Therefore, when the control device 300 is stopped due to a failure or the like, a limiter (by autonomously lowering the output voltage of the rectifier 400 in which the problem occurs). Fail safe) can be expected.
Further, by operating in the saturation region, the voltage drop of the substation 800b (light load) in FIG. 8 can be increased, so that the effect of introducing the power conversion system 1 can be further enhanced.

  As described above, the concept of the saturation region is completely different between the general usage of the reactor and the usage of the reactor in the power conversion system 1. In general, a reactor is operated in a non-saturated region so as not to enter a saturated region. On the other hand, the power conversion system 1 uses the saturation region positively and operates in the saturation region except for the small current region. The operation area of the reactor can be easily designed by adjusting the cross-sectional area of the iron core and the number of windings. For example, in order to mainly use the saturation region, it is sufficient to design under conditions that easily cause magnetic saturation. Therefore, the cross-sectional area of the iron core may be reduced or the number of windings may be increased as compared with a general reactor.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes a change in a range without departing from the gist of the present invention. For example, a monorail or a new transportation system in which a portion described as a track in the present specification includes a guideway and an independent return track is also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Power conversion system 100 Rectifier transformer 200 Voltage regulator 300 Controller 400 Rectifier 710 Commercial power system 720 Power receiving circuit breaker 730 Transaction power meter 800 Substation 810 Internal bus 820 Transformer circuit breaker 830 DC high speed circuit breaker 910 Train Line 920 Rail 930 Vehicle

According to the first aspect of the present invention, a power conversion system includes a transformer for converting a voltage of AC power to be received, a rectifier for converting AC power to DC power and outputting the DC power to a load side, and a variable inductance. A voltage regulator that is configured using a variable reactor and that is provided between the transformer and the rectifier and that changes a voltage drop rate of AC power obtained by converting the voltage of the transformer .

According to the third aspect of the present invention, the power conversion method converts the voltage of the AC power to be received by a transformer, is configured using a variable reactor having a variable inductance, and includes a variable inductor between the transformer and the rectifier. In the provided voltage adjusting device, the transformer changes the voltage drop rate of the AC power obtained by converting the voltage, and adjusts the voltage of the AC power output from the transformer by the voltage adjusting device. And converting the output AC power into DC power with the rectifier and outputting the DC power to the load side.

Claims (5)

A transformer for converting the voltage of AC power to be received,
A rectifier that converts AC power to DC power and outputs it to the load side;
A voltage adjusting device provided between the transformer and the rectifier to adjust a voltage,
A power conversion system comprising: 2. The power conversion system according to claim 1, wherein the voltage regulator is configured using a variable reactor having a variable inductance, and the transformer changes a voltage drop rate of AC power obtained by converting the voltage. 3.   The power conversion system according to claim 2, wherein the voltage regulator changes the inductance by changing a magnetic flux in the core according to a change in a DC current flowing through a control winding wound on the core of the reactor. A power conversion system according to any one of claims 1 to 3,
Train lines and return lines that can be combined with the power conversion system and constitute an electric circuit,
A vehicle that travels on the track by obtaining power from the power conversion system from the train line,
Transportation system equipped with. The voltage of AC power to be received is converted by a transformer,
Adjusting the voltage of the AC power output from the transformer with a voltage regulator,
A power conversion method, comprising: converting AC power output from the voltage regulator to DC power with a rectifier and outputting the DC power to a load side.

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