WO2020059880A1

WO2020059880A1 - Ac voltage output system, power system control system, power system, dc power transmission system, power generation system, and battery system

Info

Publication number: WO2020059880A1
Application number: PCT/JP2019/037111
Authority: WO
Inventors: 加藤　修治; 良和 ▲高▼橋; 哲郎遠藤
Original assignee: 国立大学法人東北大学
Priority date: 2018-09-21
Filing date: 2019-09-20
Publication date: 2020-03-26
Also published as: JPWO2020059880A1; JP7299628B2

Abstract

Provided are an AC voltage output system, a power system control system, a power system, a DC power transmission system, a power generation system, and a battery system, with which operation can be continued even when a power source for driving a switch has been lost. The AC voltage output system comprises at least one arm to which a plurality of unit converters 3 that output a prescribed voltage are connected in series. Each unit converter 3 comprises: a first switch arm 13 to which a first switch 13H and a second switch 13L are connected in series; a second switch arm 14 to which a third switch 14H and a fourth switch 14L are connected in series; and a power reservoir 15 that can be charged and discharged. The end on the first switch 13H side of the first switch arm 13 is connected to the end on the third switch 14H side of the second switch arm 14, and the end on the second switch 13L side of the first switch arm 13 is connected to the end on the fourth switch 14L side of the second switch arm 14, and the first switch arm 13, the second switch arm 14, and the power reservoir 15 are connected in parallel. The first switch 13H and the third switch 14H, the second switch 13L and the fourth switch 14L, or the first switch 13H, the third switch 14H, the second switch 13L, and the fourth switch 14L are each constituted by a normally-on switching element.

Description

AC voltage output system, power system control system, power system, DC transmission system, power generation system and battery system

The present invention relates to an AC voltage output system, a power system control system, a power system, a DC power transmission system, a power generation system, and a battery system.

As a power storage system capable of high-efficiency power conversion, a plurality of unit converters configured by connecting a switch circuit (power conversion circuit) and a DC power supply (capacitor) are connected in series. 2. Description of the Related Art A multiplex inverter type power storage system configured to combine and output output voltages of a power supply circuit is known (see Patent Document 1).

In the power storage system disclosed in Patent Literature 1, since a plurality of unit converters are connected in series, a control device fails, a power supply for driving a switch fails, or a power supply line is disconnected. As a result, when the power supply for driving the switch of one unit converter is lost and the unit converter cannot operate, the other unit converters also need to stop operating and stop operating the power storage system. .

In a system in which a plurality of unit converters are connected in series, such as the power storage system disclosed in Patent Document 1, the system is continued even when the power of one of the unit converters is lost. As a method of operating the unit converter, Patent Document 2 discloses that a short-circuit switch is provided in each unit converter, and when the unit converter loses power, the short-circuit switch is turned on to short-circuit the unit converter that has lost power. (See Patent Document 2).

JP 2006-174663 A JP 2011-193615 A

However, in the conventional power storage system, in order to continue the operation of the AC voltage output system when the power for driving the switch is lost, it is necessary to provide a short-circuit switch in the unit converter and short-circuit the unit converter in which the power is lost. there were. The large size of the short-circuit switch also increases the size of the AC voltage output system. Also, providing a short-circuit switch increases costs. Therefore, there is a need for an AC voltage output system that does not require a short-circuit switch and that can be continuously operated even when the power for driving the switch is lost.

Therefore, the present invention has been made in view of the above-described problems, and allows an AC voltage output system, a power system control system, a power system, and a DC power transmission system that can be continuously operated even when a power supply for driving a switch is lost. , A power generation system and a battery system.

The AC voltage output system according to the present invention includes at least one arm in which a plurality of unit converters that output a predetermined voltage are connected in series, and the unit converter includes a first switch and a second switch connected in series. A first switch arm, a second switch arm in which a third switch and a fourth switch are connected in series, and a chargeable / dischargeable power storage unit, and the first switch side end of the first switch arm. The second switch arm is connected to the third switch side end of the second switch arm, and the first switch arm is connected to the second switch side end of the first switch arm and the fourth switch side end of the second switch arm. The first switch arm, the second switch arm, and the power storage device are connected in parallel, and the first switch, the third switch, and the second switch are connected in parallel. And the fourth switch or said first switch, said third switch, said second switch and said fourth switch is constituted by a normally-on type switching element.

The AC voltage output system according to the present invention includes at least one arm in which a plurality of unit converters that output a predetermined voltage are connected in series, and the unit converter includes a first switch and a second switch connected in series. A first switch arm, a second switch arm in which a third switch and a fourth switch are connected in series, and a chargeable / dischargeable power storage unit, and the first switch side end of the first switch arm. The second switch arm is connected to the third switch side end of the second switch arm, and the first switch arm is connected to the second switch side end of the first switch arm and the fourth switch side end of the second switch arm. The first switch arm, the second switch arm, and the power storage device are connected in parallel, and the first switch, the third switch, and the second switch are connected in parallel. And the fourth switch or the first switch, the third switch, the second switch, and the fourth switch are each configured by a switching element using a field-effect transistor that realizes a low on-voltage by using a two-dimensional electron gas. I have.

The AC voltage output system according to the present invention includes at least one arm in which a plurality of unit converters that output a predetermined voltage are connected in series, and the unit converter includes a first switch and a second switch connected in series. A first switch arm, a second switch arm in which a third switch and a fourth switch are connected in series, and a chargeable / dischargeable power storage unit, and the first switch side end of the first switch arm. The second switch arm is connected to the third switch side end of the second switch arm, and the first switch arm is connected to the second switch side end of the first switch arm and the fourth switch side end of the second switch arm. The first switch arm, the second switch arm, and the power storage device are connected in parallel, and the first switch, the third switch, and the second switch are connected in parallel. And the fourth switch or said first switch, said third switch, said second switch and said fourth switch is constituted by a switching element using a field-effect transistor composed of a gallium nitride.

The AC voltage output system according to the present invention includes at least one arm in which a plurality of unit converters that output a predetermined voltage are connected in series, and the unit converter includes a first switch and a second switch connected in series. A first switch arm, a second switch arm in which a third switch and a fourth switch are connected in series, and a chargeable / dischargeable power storage unit, and the first switch side end of the first switch arm. The second switch arm is connected to the third switch side end of the second switch arm, and the first switch arm is connected to the second switch side end of the first switch arm and the fourth switch side end of the second switch arm. The first switch arm, the second switch arm, and the power storage device are connected in parallel, and the first switch, the third switch, and the second switch are connected in parallel. The fourth switch or the first switch, the third switch, the second switch, and the fourth switch are each configured by a switching element using a field-effect transistor formed of gallium nitride; An effect transistor is formed on silicon.

The power system control system according to the present invention includes a system control device that controls a power system to which an AC power distribution system or an AC power transmission system is connected, and the system control device is configured based on a frequency of the AC power distribution system or the AC power transmission system. Thus, the output of any one of the AC voltage output systems connected to the AC distribution system or the AC transmission system is controlled.

An electric power system according to the present invention is an electric power system to which an AC power distribution system or an AC power transmission system is connected, and any one of the AC voltage output systems is connected to the AC power distribution system or the AC power transmission system, and An output of the AC voltage output system is controlled based on a frequency of a system or the AC transmission system.

The power system control system according to the present invention includes a system control device that controls a power system to which an AC power distribution system or an AC power transmission system is connected, and the power system includes a plurality of the AC power distribution systems or a plurality of the AC power transmission systems. Connected in parallel, any one of the AC voltage output systems described above is connected to at least one of the plurality of AC power distribution systems or the plurality of AC power transmission systems, the system control device, the output of the AC voltage output system To control the power flow of the AC distribution system or the AC transmission system.

An electric power system according to the present invention is an electric power system to which an AC power distribution system or an AC power transmission system is connected, wherein a plurality of the AC power distribution systems or a plurality of the AC power transmission systems are connected in parallel, and a plurality of the AC power distribution systems. Any one of the AC voltage output systems described above is connected to at least one of a system or a plurality of the AC transmission systems, and the output of the AC voltage output system controls the power flow of the AC distribution system or the AC transmission system.

A DC power transmission system according to the present invention includes any one of the AC voltage output systems described above, wherein a DC power line is connected to the DC terminal, and DC power input from the DC power line to the DC terminal is converted into AC power. And output from the AC terminal.

A power generation system according to the present invention includes any one of the AC voltage output systems described above, and an active power source is connected to the DC terminal, and converts DC power input from the active power source to the DC terminal into AC power. Output from the AC terminal.

バッテリ A battery system of the present invention includes any one of the AC voltage output systems described above.

According to the present invention, when the power supply for driving the switch of the unit converter is lost, the unit converter is short-circuited, so that the continuous operation can be performed even when the power supply for driving the switch is lost.

1 is a schematic diagram illustrating a configuration of an AC voltage output system according to the present invention. It is a schematic diagram showing the composition of the unit converter of the alternating current voltage output system of the present invention. FIG. 3A is a schematic cross-sectional view showing an example of an FET made of GaN. FIG. 3B shows a GaN-FET and a control circuit of a gate driver and a unit converter for driving the gan-FET on the same silicon substrate. It is a schematic sectional drawing which shows an example when it is provided. FIG. 4A is a schematic diagram showing an example of a configuration of a switching element in which a normally-on type switching element is improved to a normally-off type, and FIG. 4B is a diagram showing the normally-off type switching element of FIG. It is the schematic which shows an example of the switching element improved to the type | mold. It is a schematic diagram showing a distribution system stabilization device of a modification. It is the schematic which shows the structure of the alternating current voltage output system of a modification.

(1) Overall Configuration of AC Voltage Output System of Embodiment of the Present Invention As shown in FIG. 1, an AC voltage output system 1 of the present embodiment is connected to an AC power distribution system (hereinafter simply referred to as a power distribution system) 510. It is used as a distribution system stabilizing device for receiving and transmitting power and stabilizing the distribution system 510. In this case, the AC voltage output system 1 is connected to the distribution line of the distribution system 510 between the power system 50 and the load 56. Although the power system 50 is grouped into circuit symbols indicating voltage sources, various system configurations are possible. For example, similar to a domestic power system or the like, the frequency may change depending on the relationship between power demand and supply. If the input of mechanical energy or light energy to a generator (not shown) is larger than the output of the generator, the frequency will be higher, and if it is lower, the frequency will be lower. Also, unlike the above, a system to which only a generator via a power converter is connected is one example of the power system 50. The AC voltage output system 1 includes an R-phase arm 2R, an S-phase arm 2S, and a T-phase arm 2T as arms. Each of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T includes four unit converters 3 that output a predetermined voltage, and the four unit converters 3 are connected in series. One end of each of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T is connected to the

terminals

53u, 53v, 53w of the

distribution lines

57u, 57v, 57w of the distribution system 510 via the

reactors

150R, 150S, 150T. , The other end is star-connected at a connection point NP. As described above, the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T are connected in parallel between the connection point NP and the power distribution system 510.

As shown in FIG. 2, the unit converter 3 includes a first switch arm 13 in which a first switch 13H and a second switch 13L are connected in series, and a third switch 14H and a fourth switch 14L connected in series. A second switch arm 14 and a power storage 15 that can be charged and discharged. The power storage device 15 is configured by, for example, a secondary battery such as a lithium ion battery, a nickel hydride battery, and a nickel cadmium battery. The power storage 15 is not particularly limited as long as the power can be charged and discharged, and may be a capacitor, an electric double layer capacitor, a DC flywheel, or the like.

As described above, since the AC voltage output system 1 includes the power storage units 15 in which the unit converters 3 can charge and discharge power, it is possible to store electric energy by charging the power storage units 15, It can be used as a power storage device.

The unit converter 3 includes an end of the first switch arm 13 on the side of the first switch 13H, an end of the second switch arm 14 on the side of the third switch 14H, and one terminal of the power storage device 15 (in this embodiment, (Positive side), the end of the first switch arm 13 on the second switch 13L side, the end of the second switch arm 14 on the fourth switch 14L side, and other terminals of the power storage device 15 (this embodiment). In the figure, the minus side is connected. As described above, the unit converter 3 has a full bridge circuit configuration in which the first switch arm 13, the second switch arm 14, and the power storage unit 15 are connected in parallel.

The unit converter 3 is connected to a control circuit (not shown). The first switch 13H, the second switch 13L, the third switch 14H, and the fourth switch 14L are provided with a drive voltage (for example, a drive voltage for controlling on / off of each switch). , A gate voltage in the case of a switching element constituted by an FET (field effect transistor).

The unit converter 3 is configured such that the first terminal FT is pulled out from the connection point 10 between the first switch 13H and the second switch 13L of the first switch arm 13, and the third switch 14H and the fourth switch 14L of the second switch arm 14 A second terminal ST is drawn out from a connection point 12 with the second terminal ST. Assuming that the voltage of the power storage unit 15 is V, the unit converter 3 turns on / off the first switch 13H, the second switch 13L, the third switch 14H, and the fourth switch 14L, thereby connecting the first terminal FT to the first terminal FT. A three-level voltage of ± V and zero can be output between the second terminal ST. Note that each unit converter 3 may be configured to output the same voltage, and a different voltage may be output by appropriately changing the configuration (such as the capacity of a battery) of the power storage unit 15 of each unit converter 3. May be configured.

In the AC voltage output system 1 shown in FIG. 1, the first terminal FT of one unit converter 3 and the second terminal ST of another unit converter 3 are connected, and a plurality of unit converters 3 are connected in series. It is connected. Therefore, the AC voltage output system 1 switches the number of the unit converters 3 that output voltage in the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T, so that the number of the unit converters 3 is changed. Each arm can output a multi-step voltage. Further, the AC voltage output system 1 includes a control device that controls a control circuit of each unit converter 3. The control device sends to the control circuit of each unit converter a command for the control circuit to control on / off of the switch of each unit converter, and outputs the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T. To output multi-stage AC voltage. In the present embodiment, the case where the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T each include four unit converters 3 has been described, but the number of unit converters 3 included in each arm is described. Is not limited. When the number of unit converters 3 provided in each arm is large, the number of stages of the AC voltage output by the AC voltage output system 1 increases, and the waveform of the AC voltage is closer to a sine wave even when the switching frequency of each switching element is low. Can be a waveform. Therefore, the switching loss of the semiconductor can be reduced. In addition, since a voltage waveform close to a sine wave can be output, there is a merit that a harmonic filter can be eliminated or simplified. Further, since high voltage can be output by using multiple stages, there is an advantage that the step-up / step-down transformer can be omitted depending on the system.

In the unit converter 3, since the first switch arm 13 and the second switch arm 14 are connected in parallel, the first switch 13H and the third switch 13H are connected between the first terminal FT and the second terminal ST. 14H are connected in series (reverse series), and the second switch 13L and the fourth switch 14L are connected in series. Here, one of the switches connected in series between the first terminal FT and the second terminal ST (the first switch 13H and the third switch 14H) is a first switch group 16, and the other of the switches connected in series ( The second switch 13L and the fourth switch 14L) are referred to as a second switch group 17.

The unit converter 3 includes switches (the first switch 13H and the third switch 14H) of the first switch group 16, each switch (the second switch 13L and the fourth switch 14L) of the second switch group 17, or the first switch group. Each of the switches (the first switch, the third switch, the second switch, and the fourth switch) of the switch group 16 and the second switch group 17 is configured by a normally-on type switching element. Here, the normally-on type switching element referred to in this specification refers to a switching element in which a switch is on when a driving voltage for controlling on / off of the switch is zero. Note that a normally-off type switching element is a switching element in which a switch is in an off state when a driving voltage is zero, and is generally used as a switch in the field of power electronics. Semiconductor FET (Si-MOSFET), insulated-gate bipolar transistor (IGBT), gate turn-off thyristor (GTO), gate commutated turn-off thyristor (Gate Commutated Turn-off thyristor: GCT).

In the present embodiment, the unit converter 3 is configured such that each switch of the first switch group 16 is configured by an IGBT that is a normally-off type switching element, and each switch of the second switch group 17 is a normally-on type switching element. (Hereinafter, also referred to as HEMT). Further, in the present embodiment, an FET made of GaN (gallium nitride) (hereinafter, also referred to as a GaN-FET) is used as the HEMT. This GaN-FET is a GaN-FET formed on Si (silicon), for example, on a Si substrate. The HEMT is a field-effect transistor that realizes a lower on-state voltage than a normal FET that uses a high-mobility two-dimensional electron gas induced in a semiconductor heterojunction as a channel and applies a voltage to a gate to turn on. . Since the HEMT has a low on-voltage, it can reduce power consumption by switching the switch on and off, and since it is a high breakdown voltage FET, it is connected to a power distribution system of about 100 V to 6.6 kV or a higher voltage power transmission system. Suitable for the AC voltage output system 1. In particular, the GaN-FET has a lower switching loss than Si in a high voltage region, and is therefore more suitable for the AC voltage output system 1 that handles a high voltage. Furthermore, in the case of the present embodiment, since the GaN-FET is formed on the Si substrate, it can be manufactured at lower cost than when the GaN-FET is formed on the GaN substrate, which is more preferable. Note that a normally-on depletion mode MOS-FET can also be used as a switching element using a field-effect transistor in which a low on-voltage is realized by a two-dimensional electron gas.

構成 The configuration of the GaN-FET used in the present embodiment will be described. As shown in FIG. 3A, the GaN-FET 20 is formed on a Si substrate 21. The GaN-FET 20 includes a GaN layer 22 formed on a Si substrate 21, an AlGaN layer 23 formed in contact with the GaN layer 22, a source electrode 24, a drain electrode 25 formed in contact with the AlGaN layer 23, and a gate. The semiconductor device includes an insulating layer 27 and a gate electrode 26 formed in contact with the gate insulating layer 27. In the GaN-FET 20, a two-dimensional electron gas layer is formed at the interface between the AlGaN layer 23 and the GaN layer 22, and the two-dimensional electron gas layer becomes a conductive channel. Therefore, even if the voltage applied to the gate electrode 26 is zero, the source electrode 24 A current can flow between the drain electrodes 25; Therefore, the switching element constituted by the GaN-FET 20 is in an on state even when the drive voltage applied to the gate electrode 26 is zero, and is a normally-on type. In the switching element constituted by the GaN-FET 20, by applying a negative drive voltage to the gate electrode 26, no current flows between the source electrode 24 and the drain electrode 25, and the switching element can be turned off.

Further, as shown in FIG. 3B, as a switching element composed of the GaN-FET 20, a gate driver 28 for driving the GaN-FET 20 and a control circuit of the unit converter 3 (first switch 13H, second switch 13L, A control circuit for driving the third switch 14H and the fourth switch 14L) 19 and the like may be mounted on the same Si substrate 21. In FIG. 2, the GaN-FET 20 is enlarged for convenience of explanation. Further, the GaN-FET is not limited to the Si substrate, and may be formed on, for example, a SiC substrate or a GaN substrate. In the present embodiment, a GaN-FET switching element formed on a Si substrate is used for the second switch 13L and the fourth switch 14L, and a switching element for the second switch 13L and a switching element for the fourth switch 14L are used. Is separate. However, the switching elements for the second switch 13L and the fourth switch 14L may be formed integrally. For example, a GaN-FET for the second switch 13L and a GaN for the fourth switch 14L may be formed on one Si substrate. -An element in which an FET is formed may be used. Further, the first switch 13H and the third switch 14H may be formed integrally (on the same substrate) with the second switch 13L and the fourth switch 14L.

As described above, in the unit converter 3, each switch of the first switch group 16 is a normally-off type switching element and each switch of the second switch group 17 is a normally-on type switching element. A switch driving power supply for the control circuit to supply the driving voltage to the first switch 13H, the second switch 13L, the third switch 14H, and the fourth switch 14L fails, or the control circuit of the unit converter 3 fails. When the power supply for driving the switches (switching elements) of the unit converter 3 is lost due to the power supply line or disconnection of the power supply line, the drive voltage of each switch becomes zero, and the first switch 13H and the third switch 13H are driven. 14H is turned off, and the second switch 13L and the fourth switch 14L are turned on. That is, a short-circuit path is formed from the second terminal ST to the fourth switch 14L, the second switch 13L, and the first terminal FT in this order. Therefore, the unit converter 3 is in a state where the first terminal FT and the second terminal ST are short-circuited.

In the prior art of a converter having a configuration in which unit converters are connected in series, since all switches of the unit converter are configured with normally-off type switching elements, when power for driving the switches is lost, All the switches were turned off, the first terminal and the second terminal were insulated, and no current flowed to the unit converter and the arm to which the unit converter belonged, and the operation had to be stopped. . Therefore, the conventional AC voltage output system requires a short-circuit switch for short-circuiting between the first terminal and the second terminal.

On the other hand, in the AC voltage output system 1 of the present embodiment, when the power for driving each switch of the unit converter 3 is lost, the first terminal FT and the second terminal ST are short-circuited, and the unit conversion is performed. Since the converter 3 is short-circuited and a current flows between the first terminal FT and the second terminal ST, the current does not stop flowing to the arm to which the unit converter belongs, and the operation can be continued. Further, in the AC voltage output system 1, since the first terminal FT and the second terminal ST are in a short-circuit state, the unit converter 3 is short-circuited between the first terminal FT and the second terminal ST. There is no need to provide a switch. The unit converter 3 is a switch of the first switch group 16 (the first switch 13H and the third switch 14H) or a switch of the first switch group 16 and the second switch group 17 (the first switch 13H and the third switch 14H). , The second switch 13L and the fourth switch 14L) have the same effect even if they are constituted by normally-on type switching elements.

When each switch of the first switch group 16 is a normally-on type switching element and each switch of the second switch group 17 is a normally-off type switching element, each switch (switching element) of the unit converter 3 is When the drive power supply is lost, the drive voltage of each switch becomes zero, the first switch 13H and the third switch 14H are turned on, and the second switch 13L and the fourth switch 14L are turned off. That is, a short-circuit path is formed from the second terminal ST to the first terminal FT via the first switch 13H, the third switch 14H, and the like in this order. Therefore, the unit converter 3 is in a state where the first terminal FT and the second terminal ST are short-circuited.

When each switch (first switch 13H, third switch 14H, second switch 13L, and fourth switch 14L) of the first switch group 16 and the second switch group 17 is a normally-on type switching element, the unit is When the power supply for driving each switch (switching element) of the converter 3 is lost, the drive voltage of each switch becomes zero and all the switches are turned on. As a result, a short-circuit path from the second terminal ST to the first switch 13H, the third switch 14H, and the first terminal FT in this order, and the second switch 13L, the fourth switch 14L, and the like from the second terminal ST. A short-circuit path to the first terminal FT that passes in order is formed, and the first terminal FT and the second terminal ST are short-circuited.

As described above, in the AC voltage output system 1, the unit converter 3 is configured such that each switch (the first switch 13H and the third switch 14H) of the first switch group 16 or each of the first switch group 16 and the second switch group 17 Even when the switches (the first switch 13H, the third switch 14H, the second switch 13L, and the fourth switch 14L) are configured by normally-on switching elements, the power for driving each switch of the unit converter 3 is lost. Then, the first terminal FT and the second terminal ST are short-circuited, and the unit converter 3 is short-circuited. Then, in the AC voltage output system 1, a current flows between the first terminal FT and the second terminal ST of the unit converter 3 in which the driving power supply has been lost, so that the current flows to the arm to which the unit converter 3 belongs. The operation can be continued without disappearing.

Next, the effect when the AC voltage output system 1 as a distribution system stabilizing device is used as a frequency stabilizing device for stabilizing the frequency of the distribution system 510 will be described. As shown in FIG. 1, the AC voltage output system 1 is connected to a power distribution system 510. The power distribution system 510 connects the power system 50 and the load 56 by

distribution lines

57u, 57v, 57w, and supplies power from the power system 50 to the load 56. Here, similarly to the domestic power system, the frequency of the power system 50 is higher if the input of mechanical energy or light energy to a generator (not shown) is larger than the generator output, and if the input is lower, the frequency is lower. It is assumed that the system becomes lower. The distribution line 57u has one end connected to the u phase of the power system 50 and the other end connected to the R phase of the load 56. The distribution line 57v has one end connected to the v phase of the power system 50 and the other end connected to the S phase of the load 56. The distribution line 57w has one end connected to the w phase of the power system 50 and the other end connected to the T phase of the load 56. Here, the power system 50 includes power generation facilities such as a generator, power transmission facilities such as an AC transmission system, transformer facilities such as a transformer, distribution facilities such as an AC distribution system, and customer facilities such as loads. It is a power transmission and distribution network and is controlled by a power system control system (not shown in FIG. 1) provided at a command center or the like. The distribution system 510 and the load 56 are connected to such a power system 50.

The distribution line 57u has a terminal 53u to which the R-phase arm 2R of the AC voltage output system 1 is connected. The distribution line 57v has a terminal 53v, and the S-phase arm 2S of the AC voltage output system 1 is connected to the terminal 53v. The distribution line 57w has a terminal 53w, and the T-phase arm 2T of the AC voltage output system 1 is connected to the terminal 53w. As described above, the AC voltage output system 1 is connected to the distribution system 510. The load 56 is, for example, a customer such as a factory, or a machine or a manufacturing device possessed by the customer. Also, 52u, 52v, 52w and 51u, 51v, 51w in FIG. 1 schematically represent the reactant components and the resistance components of the

distribution lines

57u, 57v, 57w closer to the power system 50 than the

terminals

53u, 53v, 53w. 54u, 54v, 54w and 55u, 55v, 55w schematically represent the reactant components and the resistance components of the

distribution lines

57u, 57v, 57w closer to the load 56 than the

terminals

53u, 53v, 53w. .

交流 The AC voltage output system 1 as a distribution system stabilizing device can stabilize the frequency of the distribution system 510. For example, a control device (not shown in FIG. 1) receives a detection result of a three-phase package or a frequency of each phase from a frequency measuring device (not shown in FIG. 1) provided in the power distribution system 510, and performs power distribution. The frequency of the system 510 is monitored. Since a normal three-phase power system receives power supply from a three-phase generator, the frequency of each phase is the same. Here, considering that it is physically possible that only a single-phase generator is connected to each phase, there is a rather insane assumption that the frequency of each phase is not necessarily the same. It will be described on the assumption. If the frequency of each phase is different, another serious problem such as a change of the phase order occurs, but the description will focus on only the frequency. When the control device detects that the frequency of any phase has increased, it absorbs power from the phase (distribution line) having the increased frequency and detects that the frequency of any phase has decreased. The unit converters 3 of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T are controlled so as to emit power to the phase whose frequency has decreased. For example, when the frequency of the u-phase of the distribution system 510 increases, the control device controls each switch of the unit converter 3 of the R-phase arm 2R to charge the power storage 15 with the u-phase voltage. To absorb power from the u-phase and reduce the frequency of the u-phase. When the frequency of the u-phase of the distribution system 510 decreases, the control device controls each switch of the unit converter 3 of the R-phase arm 2R, so that the power storage unit 15 discharges to the u-phase. Power is released from the arm 2R to the u-phase to increase the frequency of the u-phase. Thus, the distribution system stabilizing device using the AC voltage output system 1 can stabilize the frequency of the distribution system 510.

(4) The frequency of the power distribution system 510 fluctuates due to an imbalance in power supply and demand during a system accident due to a lightning strike or the like. In an extreme case, a generator (not shown) of the power system 50 loses synchronism. Normally, the AC voltage output system 1 prevents such a situation. However, a lightning strike or the like easily damages the AC voltage output system 1 and the power supply for driving each switch of the unit converter 3 is changed. Sometimes they are lost. If the AC voltage output system 1 is according to the present invention, the operation can be continued even in a state where the driving power supply is partially lost, so that robustness against frequency fluctuations and generator step-out can be improved.

Here, the control device of the AC voltage output system 1 controls the output to the power distribution system 510 for each phase based on the frequency of each phase of the power distribution system 510 to which the AC voltage output system 1 is connected. It has been described that the frequency of each phase of the system 510 has been stabilized. However, the present invention is not limited to this, and the system control device (not shown in FIG. 1) of the above-described power system control system that controls the power system 50 to which the power distribution system 510 is connected includes Control for stabilizing the frequency may be performed. In this case, the system control device controls the output of the AC voltage output system 1 connected to the power distribution system 510 for each phase based on the frequency of each phase of the power distribution system 510, and adjusts the frequency of each phase of the power distribution system 510. Stabilize. The control method of the frequency stabilization is the same as that of the control device of the AC voltage output system 1, and the description is omitted.

Next, the effect when the AC voltage output system 1 as a distribution system stabilizing device is used as a power adjustment device between phases of the distribution system 510 will be described. For example, the power required in the u-phase, v-phase, and w-phase of the distribution system 510 is such that the u-phase has insufficient power for the power demand of the load 56 and the w-phase has excess power for the power demand of the load 56. Is unbalanced, the control device controls the switch of each unit converter 3 of the S-phase arm 2S to charge the power storage unit 15 of the unit converter 3 with the w-phase voltage. Absorb power and eliminate excess power. Then, the control device controls the switch of each unit converter 3 of the R-phase arm 2R, so that the power storage unit 15 discharges to the u-phase, and the R-phase arm 2R discharges the power to the u-phase, and the power is insufficient. To eliminate. As described above, the power distribution system stabilizing device supplies power to the u-phase with insufficient power, absorbs power from the w-phase with excessive power, adjusts the imbalance of power between phases, and stabilizes the power distribution system 510. Can be

電 The distribution system stabilization device can also balance the line voltage between the

distribution lines

57u, 57w, and 57v of the distribution system 510. For example, a control device (not shown in FIG. 1) monitors the voltage of each phase of the power distribution system 510. When the control device detects the imbalance of the line voltage from the voltage of each phase, the AC voltage output system 1 outputs a high voltage to the phase where the voltage has increased and outputs a low voltage to the phase where the voltage has decreased. The unit converters 3 of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T are controlled so as to perform the operations. For example, when the voltage of the w-phase of the distribution system 510 is high and the voltage of the u-phase of the distribution system 510 is low, the control device controls the switches of the unit converters 3 of the R-phase arm 2R and the S-phase arm 2S, A high voltage is output to the u-phase and a low voltage is output to the w-phase to balance the line voltage between the distribution line 57u and the distribution line 57w. As described above, the distribution system stabilizing device can stabilize the distribution system 510 by balancing the line voltages between the

distribution lines

57u, 57w, and 57v of the distribution system 510.

(4) The effect of lightning differs between the phases of the distribution system 510, and a ground fault occurs only in a specific phase, and imbalance of the interphase voltage occurs even when the load is dropped. Further, due to the lightning strike, the driving power supply of the corresponding phase of the AC voltage output system 1 may be lost at the same time. If the AC voltage output system 1 is according to the present invention, the operation can be continued even in a state where the driving power supply is partially lost, so that robustness against frequency fluctuations and generator step-out can be improved.

As described above, the distribution system stabilizing device using the AC voltage output system 1 can control the frequency of each phase, adjust the excess or deficiency of power between phases, cancel the imbalance of voltage between phases, The power distribution system 510 can be stabilized. Furthermore, since the power distribution system stabilizing device includes the AC voltage output system 1, even when the power for driving the switch of the unit converter 3 of the AC voltage output system 1 is lost, the power distribution system stabilization device can be continuously operated, and the reliability is higher. . Note that the AC voltage output system 1 can be connected to an AC power transmission system that connects between power systems instead of the AC power distribution system 510, and can be applied as a stabilizing device for the AC power transmission system. Further, the AC voltage output system 1 is for three-phase AC, but one arm can be removed for single-phase AC. Further, by removing the two arms and connecting the remaining one arm between the single-phase terminals at the interconnection point, it is also possible to use a single-phase terminal.

(2) Operation and Effect In the above configuration, the AC voltage output system 1 has at least one arm (R-phase arm 2R, S-phase arm 2S) to which a plurality of unit converters 3 each outputting a predetermined voltage are connected in series. , T-phase arm 2T), the unit converter 3 includes a first switch arm 13 in which a first switch 13H and a second switch 13L are connected in series, and a third switch 14H and a fourth switch 14L in series. A second switch arm 14 and a chargeable / dischargeable power storage unit 15 are connected, and an end of the first switch arm 13 on the first switch 13H side and an end of the second switch arm 14 on the third switch 14H side are provided. The first switch arm 13 is connected to an end of the first switch arm 13 on the second switch 13L side and an end of the second switch arm 14 on the fourth switch 14L side. The second switch arm 14 and the power storage 15 are configured to be connected in parallel, and the first switch 13H and the third switch 14H, the second switch 13L and the fourth switch 14L or the first switch 13H, the third switch 14H, The second switch 13L and the fourth switch 14L are constituted by normally-on switching elements.

Therefore, in the AC voltage output system 1 of the present invention, when the power supply for driving the switch of the unit converter 3 is lost, the first terminal FT and the second terminal ST are short-circuited, and the unit converter 3 is short-circuited. In this state, the operation can be continued even when the power for driving the switch is lost. Therefore, the AC voltage output system 1 can omit the short-circuit switch.
Furthermore, if the unit converter 3 is housed in one case together with control means for measuring the SOC (state of charge), SOH (state of health), etc. of the battery, the unit converter 3 functions as a battery pack with a built-in converter. Exchange can be performed smoothly when the battery has deteriorated.
Further, when the DC voltage of the unit converter 3 is as low as about 30 V or less, a plurality of unit converters 3 may be incorporated in one case having a low explosion-proof function. When the DC voltage is low, the first switch 13H and the second switch 13L of the unit converter 3 are erroneously turned on. Even if a PN short circuit occurs, the voltage is low, so that the risk of the switching element exploding is sufficiently low. In one low case
Further, when a concave portion and a convex portion are provided in each case so that a convex portion of another case can be inserted into a concave portion of one case, it is easy to connect a large number of battery packs in multiple stages. In particular, it is more preferable that one unit converter 3 and another unit converter 3 can be electrically connected by the insertion.

(3) Modifications The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. In the above embodiment, the HEMT, which is a normally-on type switching element, includes the first switch 13H and the third switch 14H, the second switch 13L and the fourth switch 14L, or the first switch 13H, the second switch 13L, and the third switch 13H. It has been described that the switch 14H and the fourth switch 14L (see FIG. 2) are used. Actually, a normally-on type switching element such as a HEMT is often commercially available as a normally-off type switching element after adding a normally-off circuit.

Such a normally-off normally-on type switching element (hereinafter, referred to as an N-OFF switching element for convenience of description) is also provided when a driving power supply is lost by adding a circuit described later. By turning on normally, the normally-on type switching element can be used as the switch (first switch, second switch, third switch, and fourth switch) of the above embodiment. Hereinafter, an example of a circuit of an N-OFF switching element and an example of a circuit for normally turning on the N-OFF switching element will be described.

FIG. 4A is a diagram showing an example of an N-OFF switching element. The N-OFF switching element 30 shown in FIG. 4A includes a normally-on switching element 29 (for example, a GaN-FET that is a HEMT) and a normally-off switching element 31 (for example, a Si-MOSFET). You have a connected configuration. 4A is a source-side terminal of the N-OFF switching element 30, and D is a drain-side terminal of the N-OFF switching element 30. A normally-on switching element 29 is disposed on the drain terminal D side, and a normally-off switching element 31 is disposed on the source side. The gate 29 </ b> G of the normally-on type switching element 29 is connected to a wiring closer to the source than the normally-off type switching element 31. The gate 31G of the normally-off switching element 31 is connected to a control circuit (not shown in FIG. 4A) of the N-OFF switching element 30, and a drive voltage for driving the normally-off switching element 31 is , From the control circuit to the gate 31G.

In the N-OFF switching element 30, when a positive driving voltage is applied to the gate 31G from the control circuit, the normally-off switching element 31 is turned on, and the normally-on switching element 29 is connected to the gate 29G. Since the applied voltage becomes equal to the source voltage of the switching element 29, the switching element 29 is turned on.

On the other hand, when the drive voltage is not applied to the gate 31G from the control circuit, the normally-off type switching element 31 is turned off. At this time, since the gate voltage of the normally-on switching element 29 is lower than the source voltage of the normally-on switching element 29, the normally-on switching element 29 is also turned off. As a result, no current can flow between the source terminal S and the drain terminal D, and the N-OFF switching element 30 is turned off. As described above, the N-OFF switching element 30 cascode-connects the normally-on switching element 29 and the normally-off switching element 30 to make the normally-on switching element 29 normally-off. I have.

One method of the present invention in which an N-OFF switching element 30, which is a switching element in which a normally-on switching element 29 is normally-off, is normally-on when a driving power supply is lost, is referred to FIG. 4B. Will be explained. Here, for convenience of description, a switching element in which the N-OFF switching element 30 is normally on is referred to as an N-ON switching element.

As shown in FIG. 4B, the N-ON switching element 37 includes a normally-on switching element 29 and a normally-off switching element 31 (the N-OFF switching element 30 shown in FIG. , A resistor 32, a Zener diode 33, and a drive voltage supply switching element 34. The resistor 32 is inserted between the gate 31G and the drain terminal D of the normally-off type switching element 31. The Zener diode 33 is inserted between the gate 31G and the source terminal S, the anode is connected to the source terminal S side, and the cathode is connected to the gate 31G side. In the present embodiment, at the connection point 35, the gate 31G, the resistor 32, and the Zener diode 33 are connected. The specifications of the resistor 32 and the Zener diode 33 are appropriately set according to the threshold voltage of the normally-off type switching element 31 and the like.

Further, the drain of the drive voltage supply switching element 34 is connected to the connection point 35. The drive voltage supply switching element 34 is connected to the control circuit (not shown in FIG. 4B) of the N-ON switching element 37 that supplies the drive voltage of the normally-off type switching element 31 to the source. The drive voltage supply switching element 34 is provided to cut off the control circuit and the connection point 35 when the power is lost. The gate 34G of the drive voltage supply switching element 34 is normally in the ON state. The drive voltage supply switching element 34 is connected to a power supply circuit of a control circuit of the N-ON switching element 37. When the drive voltage supply switching element 34 is in the ON state, the control circuit can drive the gate 34G.

On the other hand, when the power supply for driving the N-ON switching element 37 is lost, the switching element for driving voltage supply 34 is turned off, and the connection point 35 is cut off from the control circuit. As a result, the voltage at the connection point 35 rises to the voltage allowed by the Zener diode 33. The increased voltage at the connection point 35 is applied to the gate 31G of the switching element 31 and is higher than the driving voltage of the switching element 31, so that the switching element 31 is turned on. As a result, the N-ON switching element 37 is turned on. As described above, the N-ON switching element 37 is turned on when the driving power supply is lost and the driving voltage is not supplied. Therefore, even if the N-ON switching element 37 is used as a normally-on type switching element for the switch of the unit converter 3 of the above-described embodiment, the same effect as in the above-described embodiment can be obtained.

In the above embodiment, the second switch 13L and the fourth switch 14L of the unit converter 3 shown in FIG. 2 are provided with GaN-FETs formed on a Si substrate as normally-on switching elements (see FIG. 3A). Has been described. At this time, the normally-on type switching element may be one in which a GaN-FET for the second switch 13L and a GaN-FET for the fourth switch 14L are integrally formed on one Si substrate. He explained that. The present invention further provides, for example, a device in which a control circuit of the unit converter 3 is formed with a GaN-FET for the second switch 13L and a GaN-FET for the fourth switch 14L on a Si substrate mounted on Si. It may be used as a marion type switching element. Other circuits mounted on the Si substrate include, for example, a circuit corresponding to a control device that controls a control circuit of each unit converter 3 of the AC voltage output system 1, a circuit corresponding to a gate driver, and the like. When the first switch 13H and the third switch 14H are normally-on type switching elements, a GaN-FET for the first switch 13H and a third switch 14H are provided on the Si substrate on which the circuit is formed. GaN-FET is formed. Further, a normally-off type switching element used for a switch other than a switch using a normally-on type switching element may be formed on a Si substrate on which a circuit is formed. Each switch (first switch) of the unit converter 3, such as a circuit corresponding to a control device that controls the control circuit of the unit converter 3 or the control circuit of each unit converter 3 of the AC voltage output system 1, a circuit corresponding to a gate driver, etc. All the elements and all the switches that constitute a circuit for driving at least one of the switch 13H, the second switch 13L, the third switch 14H, and the fourth switch 14L) may be mounted on Si. Only the element may be mounted on Si.

In the above embodiment, the case where the AC voltage output system 1 is used for three-phase AC as shown in FIG. 1 has been described, but the present invention is not limited to this, and one arm of the AC voltage output system is used. And can be used for single-phase alternating current.

Further, in the above embodiment, as shown in FIG. 1, the case where the AC voltage output system 1 is applied as the distribution system stabilizing device of the distribution system between the power system and the load has been described. Not limited to For example, as shown in FIG. 5, the AC voltage output system 1 can be used for power flow control of

distribution systems

510 and 610 connected in parallel between the power system 50 and the power system 59. In the example shown in FIG. 5, the power system 50 and the power system 59 are interconnected by the power distribution system 510 and the power distribution system 610. Both ends of the distribution system 610 are connected to the distribution system 510, and the distribution system 510 and the distribution system 610 are connected in parallel. The AC voltage output system 1 is connected to

terminals

53u, 53v, 53w of each phase of the distribution system 510. A load (not shown in FIG. 5) is connected to each of the power distribution system 510 and the power distribution system 610.

In such a case, the distribution system stabilization device controls the frequency of each phase, adjusts the excess or deficiency of power between the phases, and controls the voltage between the phases, similarly to the distribution system stabilization device shown in FIG. Or cancel the imbalance. Further, the power distribution system stabilizing device can eliminate the situation in which the power flow between the power system 50 and the power system 59 is unbalanced in the power distribution system 510 and the power distribution system 610. For example, when the power flow of the distribution system 510 is excessive, the power storage 15 of the unit converter 3 of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T is charged by the voltage of the distribution system 510, and The power flow is reduced by absorbing power.

On the other hand, when the power flow of the distribution system 510 is insufficient (when necessary power cannot be supplied to a load (not shown in FIG. 5)), the unit conversion of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T is performed. The power flow is increased by discharging the power storage unit 15 of the unit 3 and supplying power to the distribution system 510. Also, the tide can be increased by increasing the output voltage (voltage at the interconnection point).

As described above, the AC voltage output system 1 that exchanges power with the distribution system 510 can eliminate excess or deficiency of the power flow in the distribution system. Further, the power distribution system stabilizing device using the AC voltage output system 1 can be continuously operated even when the power for driving the switch of the unit converter 3 of the AC voltage output system 1 is lost, and is more reliable. The AC voltage output system 1 may be connected to the distribution system 610 instead of the distribution system 510. A plurality of AC voltage output systems 1 may be prepared, and the AC voltage output systems 1 may be connected to both the distribution system 510 and the distribution system 610, respectively.

Here, a case is described in which the control device of AC voltage output system 1 connected to one (distribution system 510) of a plurality of

distribution systems

510 and 610 connected in parallel controls the power flow of distribution system 510 and distribution system 610. Although described, the present invention is not limited to this. A power system control device of the power system control system that controls the power system 50, the power system 59, or both, to which the power distribution system 510 is connected, controls the output of the AC voltage output system 1 connected to the plurality of power distribution systems 510, and The power flow of the system 510 and the power distribution system 610 may be controlled. The method of controlling the power flow is the same as that in the case where the control device of the AC voltage output system 1 controls the power flow, and a description thereof will be omitted. The AC voltage output system 1 may be connected to an AC transmission system that connects between power systems instead of the distribution system 510, and may be applied as a stabilizing device for the AC transmission system.

(4) Other Applications of AC Voltage Output System The AC voltage output system 1 of the present invention has a power storage unit 15 in which each unit converter 3 can charge and discharge, stores power, and at a predetermined timing. Since the stored power can be output as an AC voltage, it is used for various battery systems such as UPS (uninterruptible power supply) and electric vehicle batteries, and converters for DC power transmission, in addition to power distribution system stabilizing devices. be able to.

The AC voltage output system 1 can also be used as a UPS. For example, as shown in FIG. 1, AC voltage output system 1 is connected to a commercial AC power supply, receives a power from the commercial AC power supply, a power storage unit that stores the power received by the power reception unit, and a power storage unit. A power supply unit that supplies the stored electric power to electric devices and electronic devices. The AC voltage output system is used as the power storage unit and functions as a UPS. The AC voltage output system 1 functioning as the UPS charges an electric power storage of each unit converter of the AC voltage output system with electric power from a commercial AC power supply, and outputs the AC voltage output when the commercial AC power supply is cut off. Outputs an AC voltage, and supplies the AC voltage to an electric device or an electronic device via a power supply unit. Since the UPS includes the AC voltage output system of the present invention, the UPS can be continuously operated even when the power supply for driving the switch of the unit converter 3 of the AC voltage output system is lost, and the UPS is more reliable.

When used for a battery of an electric vehicle, the AC voltage output system 1 is connected to each phase of a three-phase AC motor instead of the power system 50 shown in FIG. Further, it is preferable to use a large-capacity secondary battery as the power storage unit 15 of each unit converter 3. Further, a terminal for charging the power storage device 15 from outside the electric vehicle is connected to each arm of the AC voltage output system 1. The battery provided with the AC voltage output system 1 is a three-phase battery that converts the power stored in the AC voltage output system 1 by charging the power storage unit 15 with the power supplied from the outside to the AC voltage output system 1. Supply to each phase of the AC motor to rotate the motor. At this time, the power storage 15 of the AC voltage output system 1 can be charged by the voltage regenerated by the motor. Since the battery of the conventional electric vehicle is a secondary battery such as a lithium ion battery, an inverter for converting a DC voltage output by the secondary battery into an AC voltage is required. On the other hand, by using the AC voltage output system 1 as the battery of the electric vehicle, the battery and the inverter can be replaced with the AC voltage output system 1, and these configurations can be omitted. Further, since the battery of the electric vehicle is provided with the AC voltage output system 1, the battery can be continuously operated even when the power supply for driving the switch of the unit converter 3 of the AC voltage output system 1 of the present invention is lost, and the reliability is further improved. high. Note that the AC voltage output system 1 can be applied to batteries of vehicles other than electric vehicles.

In the AC voltage output system 1 shown in FIG. 1, one end of each of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T is star-connected, and the other end is connected to each phase of the power distribution system via the

reactors

150R, 150S, 150T. However, the form of the AC voltage output system can be variously changed. For example, as in an AC voltage output system 110 shown in FIG. 6, a leg 110R in which two arms 112R are connected in series (also referred to as an R-phase leg) and a leg 110S in which two arms 112S are connected in series (S-phase A leg 110T (also referred to as a T-phase leg) in which two arms 112T are connected in series, and one end and the other end are connected in parallel, and an AC voltage output system is connected in parallel. It may be 110.

Each of the

arms

112R, 112S, and 112T (also referred to as an R-phase arm, an S-phase arm, and a T-phase arm) of the AC voltage output system 110 illustrated in FIG. 6 includes three unit converters 3 and a reactor 103, and the reactor 103 has an end portion. Are connected in series to come in. In the example shown in FIG. 6, the configuration of each

arm

112R, 112S, 112T is the same. In each of the

legs

110R, 110S, and 110T, the reactors 103 of the

arms

112R, 112S, and 112T are connected to each other and connected in series. Each

leg

110R, 110S, 110T has a DC terminal P1, N1 at each end for transferring DC power, and

AC terminals

113R, 113S, 113T for transferring AC power at a connection point between the arms. ing. In the AC voltage output system 110, the

legs

110R, 110S, 110T share one DC terminal P1, N1 because their ends are connected to each other.

The

AC terminals

113R, 113S, 113T are connected to the u-phase, v-phase, and w-phase of the power system 50, respectively. Therefore, the AC voltage output system 110 has a configuration in which the

legs

110R, 110S, and 110T are star-connected by the DC terminal P1 and the DC terminal N1. The unit converter 3 of each

arm

112R, 112S, 112T is the unit converter 3 shown in FIG. 2 and has a full bridge circuit configuration.

The AC voltage output system 110 is connected between the DC terminal P1 and the DC terminal N1 of each

leg

110R, 110S, 110T, for example, by connecting an active power source 105 such as a prime mover, a solar power generation device, or a wind power generation device. It can be used for a power generation system that converts DC power generated by a prime mover into multi-stage AC power according to the number of unit converters 3 and outputs the AC power to each phase of the power system 50. Further, the AC voltage output system 110 converts a DC power input from the DC power transmission line into a multi-stage AC power by connecting a DC power transmission line to the DC terminal P1 and the DC terminal N1 so that each phase of the power system 50 is connected. Can be used for DC power transmission systems that output to Conversely, in this DC power transmission system, the AC voltage output system 110 can also convert the AC power input from the power system 50 into DC power, output the DC power to a DC transmission line, and perform DC power transmission. As known information, when the unit converter 3 has a full-bridge configuration, there is an advantage that a DC output voltage is reduced at the time of a DC short-circuit accident due to a lightning strike or the like, and a short-circuit current can be suppressed.

Such an AC voltage output system 110 includes at least one arm (

arms

112R, 112S, and 112T) in which a plurality of unit converters 3 that output a predetermined voltage are connected in series. A first switch arm 13 in which a switch 13H and a second switch 13L are connected in series; a second switch arm 14 in which a third switch 14H and a fourth switch 14L are connected in series; 15, an end of the first switch arm 13 on the first switch 13H side and an end of the second switch arm 14 on the third switch 14H side, and an end of the first switch arm 13 on the second switch 13L side. And the end of the second switch arm 14 on the side of the fourth switch 14L, the first switch arm 13, the second switch arm 14, and the power storage 15 are connected in parallel, and the first switch 13H and the third switch 14H, the second switch 13L and the fourth switch 14L or the first switch 13H, the third switch 14H, the second switch 13L and the fourth switch 14L Are composed of normally-on type switching elements.

The effect of the AC voltage output system 110 will be described. For example, when a lightning strike or the like occurs, the AC voltage output system 110 may lose power for driving the switches of the unit converter 3. However, the AC voltage output system 110 is in a state where the unit converter 3 is short-circuited when the power for driving the switch of the unit converter 3 is lost, so that the continuous operation is performed even when the power for driving the switch is lost. can do. Therefore, the AC voltage output system 110 can omit the short-circuit switch.

The AC voltage output system 110 shown in FIG. 6 is for three-phase AC, but can be used for single-phase by removing two legs. Further, the number of unit converters 3 included in each

arm

112R, 112S, 112T is not limited. In this example, the AC voltage output system 110 is connected to the power system 50, but may be connected to an AC distribution system or a DC distribution system connected to the power system.

DESCRIPTION OF SYMBOLS 1 AC voltage output system 2R R phase arm 2S S phase arm 2T T phase arm 3 Unit converter 13 1st switch arm 13H 1st switch 13L 2nd switch 14 2nd switch arm 14H 3rd switch 14L 4th switch 15 Power storage 20 GaN-FET

Claims

A plurality of unit converters that output a predetermined voltage include at least one arm connected in series,
Wherein the unit converter is
A first switch arm in which a first switch and a second switch are connected in series;
A second switch arm in which a third switch and a fourth switch are connected in series;
Power storage that can be charged and discharged,
The first switch-side end of the first switch arm is connected to the third switch-side end of the second switch arm, and the second switch-side end of the first switch arm is connected to the second switch. The fourth switch side end of the arm is connected, the first switch arm, the second switch arm and the power storage are connected in parallel,
The first switch and the third switch, the second switch and the fourth switch, or the first switch, the third switch, the second switch, and the fourth switch each include a normally-on type switching element. Has an AC voltage output system.
A plurality of unit converters that output a predetermined voltage include at least one arm connected in series,
Wherein the unit converter is
A first switch arm in which a first switch and a second switch are connected in series;
A second switch arm in which a third switch and a fourth switch are connected in series;
Power storage that can be charged and discharged,
The first switch-side end of the first switch arm is connected to the third switch-side end of the second switch arm, and the second switch-side end of the first switch arm is connected to the second switch. The fourth switch side end of the arm is connected, the first switch arm, the second switch arm and the power storage are connected in parallel,
The first switch and the third switch, the second switch and the fourth switch, or the first switch, the third switch, the second switch, and the fourth switch realize a low on-voltage by a two-dimensional electron gas. AC voltage output system composed of switching elements using field-effect transistors.
A plurality of unit converters that output a predetermined voltage include at least one arm connected in series,
Wherein the unit converter is
A first switch arm in which a first switch and a second switch are connected in series;
A second switch arm in which a third switch and a fourth switch are connected in series;
Power storage that can be charged and discharged,
The first switch-side end of the first switch arm is connected to the third switch-side end of the second switch arm, and the second switch-side end of the first switch arm is connected to the second switch. The fourth switch side end of the arm is connected, the first switch arm, the second switch arm and the power storage are connected in parallel,
A field-effect transistor in which the first switch and the third switch, the second switch and the fourth switch, or the first switch, the third switch, the second switch, and the fourth switch are formed of gallium nitride AC voltage output system composed of switching elements using
A plurality of unit converters that output a predetermined voltage include at least one arm connected in series,
Wherein the unit converter is
A first switch arm in which a first switch and a second switch are connected in series;
A second switch arm in which a third switch and a fourth switch are connected in series;
Power storage that can be charged and discharged,
The first switch-side end of the first switch arm is connected to the third switch-side end of the second switch arm, and the second switch-side end of the first switch arm is connected to the second switch. The fourth switch side end of the arm is connected, the first switch arm, the second switch arm and the power storage are connected in parallel,
A field-effect type in which the first switch and the third switch, the second switch and the fourth switch, or the first switch, the third switch, the second switch, and the fourth switch are formed of gallium nitride; It is composed of switching elements using transistors,
An AC voltage output system, wherein the field effect transistor is formed on silicon.
The AC according to claim 4, wherein at least a part of elements of a circuit that drives at least one of the first switch, the second switch, the third switch, and the fourth switch is mounted on the silicon. Voltage output system.
The AC voltage output according to any one of claims 2 to 5, wherein the switching element using the field-effect transistor is a normally-off switching element that is normally on when a driving power supply is lost. system.
Connected to AC distribution system or AC transmission system,
The AC voltage output according to any one of claims 1 to 6, further comprising a control device that controls an output to the AC distribution system or the AC transmission system based on a frequency of the AC distribution system or the AC transmission system. system.
With a system control device that controls the power system to which the AC distribution system or the AC transmission system is connected,
The AC voltage output according to any one of claims 1 to 6, wherein the system control device is connected to the AC distribution system or the AC transmission system based on a frequency of the AC distribution system or the AC transmission system. A power system control system that controls the output of the system.
An AC power distribution system or an AC transmission system to which the power transmission system is connected,
The AC voltage output system according to any one of claims 1 to 6, which is connected to the AC distribution system or the AC transmission system,
A power system in which an output of the AC voltage output system is controlled based on a frequency of the AC distribution system or the AC transmission system.
Connected to one of a plurality of AC distribution systems or a plurality of AC transmission systems connected in parallel,
The AC voltage output system according to any one of claims 1 to 6, further comprising a control device that controls a power flow of the AC distribution system or the AC transmission system.
With a system control device that controls the power system to which the AC distribution system or the AC transmission system is connected,
The power system, a plurality of the AC distribution system or a plurality of the AC transmission system is connected in parallel,
The AC voltage output system according to any one of claims 1 to 6, which is connected to at least one of the plurality of AC distribution systems or the plurality of AC transmission systems,
A power system control system, wherein the system control device controls an output of the AC voltage output system to control a power flow of the AC distribution system or the AC transmission system.
An AC power distribution system or an AC transmission system to which the power transmission system is connected,
A plurality of AC power distribution systems or a plurality of AC power transmission systems are connected in parallel,
The AC voltage output system according to any one of claims 1 to 6, which is connected to at least one of the plurality of AC distribution systems or the plurality of AC transmission systems,
A power system in which a flow of the AC distribution system or the AC transmission system is controlled by an output of the AC voltage output system.
At least one leg in which the two arms are connected in series;
The leg according to any one of claims 1 to 6, wherein the leg includes a DC terminal for transmitting and receiving DC power at both ends, and an AC terminal for transmitting and receiving AC power at a connection point between the arms. AC voltage output system.
An AC voltage output system according to claim 13,
A DC transmission line is connected to the DC terminal,
A DC power transmission system that converts DC power input to the DC terminal from the DC transmission line into AC power and outputs the AC power from the AC terminal.
An AC voltage output system according to claim 13,
An active power source is connected to the DC terminal,
A power generation system that converts DC power input to the DC terminal from the active power source into AC power and outputs the AC power from the AC terminal.
A battery system comprising the AC voltage output system according to any one of claims 1 to 6.
The battery system according to claim 16, wherein the battery system is an uninterruptible power supply device or a battery for an electric vehicle.