JP2006254694A - Distributed power feeding system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To feed stable power to each load through an electronic transformer used in common with a duty cycle of substally 100% by combining natural energy-based power with a large variation factor and stable power such as midnight power or fuel cell power. <P>SOLUTION: The distributed power feeding system performs distributed power feeding to an AC exclusive load by using at least one of wind power generating system WTG, a solar power generating system PV and a fuel cell FC by using a storage battery B and a commercial AC power supply. Power voltages of the wind generating system, the solar generating system, and the fuel cell are DC power sources having each rate power voltage unified equally to the rated voltage of a DC power supply source. Until the storage battery attains a fully charged state by the DC power source, electric power supply to each prescribed AC exclusive load, electric power recharging from the fuel cell, the charging of the storage battery, and an inverse power flow to the commercial AC side are carried out if the storage battery is fully charged or the commercial AC power supply is broken down, and if the storage battery is nearly fully charged and the commercial AC power supply is not in service interruption at the time of the discharged state of the storage battery during nighttime at nighttime power supply time zone or at light-load time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The invention of this application relates to a distributed power supply system. More specifically, the invention of this application is useful for distributed power supply that combines natural energy, fuel cells, and stored energy of nighttime and midnight power. In particular, a plurality of AC / DC energy sources are connected to electronic transformers, diodes, ORs. The present invention relates to a new distributed power supply system that can be interconnected by a circuit and efficiently supply power to a load.

  As a representative example of clean energy, solar power generation has become widespread. Wind power generation has also been introduced in some areas. Due to changes in weather and meteorological conditions, these natural energies are subject to constant fluctuations in daylight hours, windmill operating time ratios, and generated power, making it difficult to stably supply power. There are many examples that are used as a useful energy source.

  However, the 21st century power supply system that suppresses global warming has been studied on a global scale, and in addition to central power generation such as nuclear power, thermal power, and hydropower, efficient power supply means by distributed power supply closely linked to the consumption area Various studies are underway.

  Furthermore, even in the conventional centralized power generation, a system for effectively using night / midnight power has been introduced in order to level out large fluctuations in power consumption during the day and night and to operate the dispatch power system efficiently. .

  On the other hand, in the field of power electronics, electronic transformers for both AC and DC that have not been realized with conventional copper-iron type transformers have been developed, enabling power conversion regardless of AC or DC energy sources. Yes. Therefore, AC power, such as commercial power and wind power, and DC power, such as sunlight, fuel cells, and midnight power storage batteries, are connected by an electronic transformer. However, it can be used at homes and offices as an uninterruptible power supply that allows instantaneous interruption within half a cycle.

  Currently, there are light bulbs, inverter type fluorescent lamps, electric tools, etc. that can be used interchangeably and dc surely in household appliances that are popular in Japan, such as air conditioners, refrigerators, microwave ovens, vacuum cleaners, personal computers, fax machines, etc. With the exception of models that partially incorporate voltage doubler rectifier circuits and AC protection circuits, inverters can be used in principle. On the other hand, thyristor phase control type dimmers, heaters, and rice cookers are currently unusable with direct current. Therefore, for the time being, there is an inconvenience that separate AC wiring equipment and AC / DC home appliances must use an indoor wiring system (outlet).

  However, the conventional method always converts the DC power generation energy back to commercial AC through the inverter, converts it back to DC within the actual load, and then converts it into DC power and further converts it to high frequency inverter and variable frequency AC power to drive the motor and compressor. There are many losses.

FIG. 1 is a diagram categorizing the applicability of AC / DC power supply of conventional home appliances when AC / DC energy sources are used in a distributed power supply system in a low-voltage distribution system. Showing the relationship. For example, the efficiency when a fluorescent lamp is turned on from solar power generation is η ₁ , η ₂ , and η ₃ , and when operating a personal computer or FAX, η ₁ , η ₂ , η ₃ , and η ₄ are obtained.

  FIG. 2 shows a conventional example of solar power generation and wind power generation in a case where an AC / DC energy source is directly supplied to a load in a low voltage distribution system. As illustrated in FIG. 2, conventionally, sunlight directly supplies power to both a commercial AC power source and a load via a grid-connected inverter (common name: power conditioner), and wind power generation is a time of generated power. Since the fluctuations are severe, each system has been configured as a separate system in which system storage is performed via a bidirectional converter having a charge / discharge function after storage in a storage battery. For sunlight, the active power generation time during the day is 6-8 hours even in fine weather, while the weekly or monthly power generation time ratio of wind power generation varies greatly depending on the season and region, but our average power generation time ratio Is expected to be lower than the solar power generation time ratio. This is one of the reasons why it is not widely used compared to the West.

  Thus, if a control device such as an inverter is provided for each electric power of an energy generation source having a low operation ratio, the cost of the entire system increases and becomes one of the factors that hinder the spread of the system.

  Therefore, in view of the circumstances as described above, the invention of this application is a combination of natural energy power having a large variation factor and stable power such as midnight power and fuel cell, and is commonly used at a usage rate close to 100%. To provide a new distributed power supply system that can supply stable power to the load via the electronic transformer used, increase the price / performance ratio of the entire system, promote the spread of distributed power supply and save energy It is an issue.

  In order to solve the above-described problems, the invention of this application firstly uses both a wind power generator, a solar power generator, and a fuel cell, a storage battery, and a commercial AC power source. A distributed power supply system that performs distributed power supply to an AC-dedicated load with or without a direct-current DC-DC converter and a two-winding electronic transformer, and each of a wind power generator, a solar power generator, and a fuel cell The DC power source with the rated power voltage unified with the rated voltage of the storage battery, the two-winding electronic transformer has two bidirectional input / output terminals for both AC and DC, and the high-frequency transformer and its storage battery Modulation / demodulation semiconductor switch provided on the load side and the load side, one bidirectional input / output terminal of the two-winding electronic transformer is connected to the output side of the DC power source and the other bidirectional input / output Terminal is quotient The AC power supply and the AC dedicated load are connected in a T-shape, and the AC power from the commercial AC power supply is supplied to the bidirectional DC-DC converter and two-winding electronics until the storage battery is fully charged by the DC power source. When the accumulator battery is fully charged or the commercial ac power supply is interrupted without passing through the transformer, the dc power from the dc power source and accumulator is simply converted by the half-cycle sine wave modulation of the bidirectional DC-DC converter. After converting into a phase full-wave rectified waveform, the high-frequency modulation phase of two or two pairs of unidirectional semiconductor switches constituting the modulation / demodulation semiconductor switch provided on the storage battery side of the high-frequency transformer of the two-winding electronic transformer is commercial frequency Reversed alternately every half cycle, and demodulated by a modulation / demodulation semiconductor switch provided on the load side of the high-frequency transformer of the two-winding electronic transformer to extract the sine wave AC output Supply to AC dedicated load, replenish power from fuel cell when battery discharge progresses, supply AC power from commercial AC power source to AC dedicated load during night and midnight power supply time, and double winding electronic transformer The battery is charged using the bidirectional and AC / DC conversion function of the converter and the step-up type high power factor rectification operation when charging the bidirectional DC-DC converter, and the battery is almost fully charged at light load. And when the commercial AC power supply is not blackout, DC power is converted into AC by the bidirectional energy transmission characteristics of the two-winding electronic transformer, and the phase is automatically phase-synchronized to the commercial AC power supply side. A distributed power supply system is provided.

  Second, using a bidirectional DC-DC converter and a three-winding electronic transformer using at least one of a wind power generator, a solar power generator, and a fuel cell, a storage battery, and a commercial AC power source. A distributed power supply system that performs distributed power supply to an AC-dedicated load. Wind power generators, solar power generators, and fuel cells are DC power sources in which each rated power voltage is unified with the rated voltage of the storage battery. The three-winding electronic transformer has three bidirectional input / output terminals for both AC and DC, and has a high-frequency transformer and a modulation / demodulation semiconductor switch provided on the commercial AC power supply side, storage battery side and load side. The DC power source and the storage battery, the commercial AC power source and the AC dedicated load are mutually insulated and connected by the three-winding electronic transformer, and until the storage battery reaches full charge by the DC power source AC power from a direct current power supply is supplied to a dedicated AC load via a three-winding electronic transformer, and the DC power from the DC power source and storage battery is bidirectional DC when the storage battery is fully charged or when a commercial AC power supply fails. -Two or two pairs of modulation / demodulation semiconductor switches provided on the storage battery side of the high-frequency transformer of the three-winding electronic transformer after being converted into a single-phase full-wave rectified waveform by half-cycle sine wave modulation of the DC converter The high-frequency modulation phase of the unidirectional semiconductor switch is alternately reversed every half cycle of the commercial frequency, and is demodulated by the modulation / demodulation semiconductor switch provided on the load side of the high-frequency transformer of the three-winding electronic transformer to generate a sinusoidal AC output Take out and supply to AC dedicated load, replenish the power from the fuel cell when the battery discharges, and use AC power from commercial AC power source for AC only during night and midnight power supply time In addition to supplying to the load, the battery is charged by using the bidirectional and AC / DC conversion function of the three-winding electronic transformer and the step-up high power factor rectification operation when charging the bidirectional DC-DC converter. When the storage battery is almost fully charged at light load and the commercial AC power supply is not out of power, the DC power is converted to AC using the energy bidirectional transmission characteristics of the three-winding electronic transformer and automatically turned to the commercial AC power supply side. A distributed power feeding system characterized in that the reverse power flow is synchronized with the phase of the power supply.

  Thirdly, the present invention provides a distributed power supply system capable of storing compressed hydrogen for the fuel cell.

According to the invention of this application as described above, for example, as illustrated in FIG. 3, when both the AC and DC sources are directly supplied to the load, the efficiency η _{1 of} the inverter is removed compared to the conventional example of FIG. , Efficiency will be improved. In addition, for safety reasons, it is conceivable to insert a device that serves both as an insulation and a transformer between the commercial AC power supply and the distributed power generation equipment. In this case, the efficiency of η ₁ ′ is considered again. Although necessary, the efficiency η ₁ of a DC-AC inverter of several kilowatts or less including an insulation function is around 90%, and the efficiency η ₁ ′ of an electronic transformer of the same capacity is 94 to 95%, and η ₁ < Since η ₁ ′, the system according to the invention of this application is excellent.

[First Reference Embodiment]
FIG. 4 shows a reference embodiment of the invention of this application.

  In the reference embodiment shown in FIG. 4, first, a wind power generator WTG (Wind Turbine Generator), a solar power generator PV (Photo Voltaic), and a fuel cell FC (Fuel Cell) are used in combination. Each of the rated power voltages is a DC power source in which the rated voltage of the storage battery B (Battery) is unified. Then, until the storage battery B is fully charged by the DC power sources WTG, PV, FC, AC power from the commercial AC power supply Utility is supplied to the AC / DC load Lac / dc, and the storage battery B reaches full charge. When the DC power from the storage battery B is supplied to the AC / DC load Lac / dc and the discharge of the storage battery B advances and approaches the end of discharge, the AC power from the commercial AC power supply Utility is supplied to the AC / DC load Lac / dc. It is configured to supply, and switching between the DC power supply and the AC power supply is controlled by a control circuit (not shown).

  The storage battery B is normally charged by the wind power generation device WTG and the solar power generation device PV. When the generated power is not sufficient, the storage battery B is charged by the fuel cell FC during the daytime. In the time zone when the electricity charge is reduced, it is performed by night / midnight power via the charger CHG1.

  When the storage battery B reaches full charge, the switch SW is opened by an instruction from the control circuit, the AC relay RL is restored and switched to the DC power supply, and DC power is continuously supplied to the AC / DC load Lac / dc.

  When the end of discharge of the storage battery B is approaching, the switch SW is closed by an instruction from the control circuit, and the AC power supply is returned to the commercial AC power supply Utility.

[Second Reference Embodiment]
FIG. 5 shows another reference embodiment of the invention of this application.

  In the reference embodiment shown in FIG. 5, a bidirectional DC-DC converter Conv and a two-winding electronic transformer 2 are provided, and the two-winding electronic transformer 2 includes a storage battery side voltage and a load side voltage. High-frequency transformer HFT having matching and insulation functions, modulation / demodulation semiconductor switches SW3 and SW2 operating at 10 to 50 kHz connected to the storage battery side winding and load side winding, and filter F2 connected to the load side It consists of

  This two-winding electronic transformer 2 has two bidirectional input / output terminals 2a and 2b for both AC and DC use. One bidirectional input / output terminal 2a is connected to the output side of the DC power source, and the other both The direction input / output terminal 2b connects the commercial AC power supply Utility and the AC / DC load Lac / dc in a T shape.

  In such a circuit configuration, the AC power from the commercial AC power supply Utility is not passed through the two-winding electronic transformer 2 until the storage battery B reaches full charge by the DC power sources WTG, PV, FC. DC power is supplied to dc, and DC power sources WTG, PV, FC and DC power from storage battery B are used for both AC and DC via the two-winding electronic transformer 2 when the storage battery B is fully charged or when the commercial AC power supply Utility fails. Supply to the load Lac / dc, replenish the power from the fuel cell FC when the discharge of the storage battery B is proceeding, and AC power from the commercial AC power supply Utility to the AC / DC load Lac / dc at night and midnight power supply time While supplying, the storage battery B is charged by the bidirectionality and the AC / DC conversion function of the two-winding electronic transformer 2.

  And the fluctuation of the storage battery voltage due to charging / discharging is regulated by the voltage adjustment function of the bi-directional DC-DC converter Conv regardless of the charging / discharging, and the voltage change of the storage battery B is adjusted to the AC / DC load Lac / dc. A stable voltage can be supplied.

  In addition, since the two-winding electronic transformer 2 can transmit energy in both the forward and reverse directions using bidirectionality and AC / DC conversion function, the night / midnight power is linked with the bidirectional DC-DC converter Conv. Can serve as a charger (CHG in FIG. 1).

[Third Reference Embodiment]
FIG. 6 shows still another reference embodiment of the invention of this application.

  In the reference embodiment shown in FIG. 6, in order to adjust the insulation between the commercial AC power supply Utility and the AC / DC load Lac / dc and the fluctuations in the power supply voltage, three AC / DC inputs are used. A three-winding electronic transformer 3 having output terminals 3a, 3b, 3c is provided, and a DC power source WTG, PV, FC, a storage battery B, a commercial AC power supply Utility, and an AC / DC load Lac / dc are mutually connected. Insulated and connected to each other. The three-winding electronic transformer 3 is connected to a high-frequency transformer HFT having a matching and insulating function between the storage battery side voltage and the load side voltage, and its commercial AC power supply side winding, storage battery side winding, and load side winding. The modulation / demodulation semiconductor switches SW1, SW3 and SW2 operating at 10 to 50 kHz, and the filters F1 and F2 connected to the commercial AC power supply side and the load side are also included.

  In such a circuit configuration, until the storage battery B reaches full charge by the DC power sources WTG, PV, FC, the AC power from the commercial AC power source Utility is supplied to the AC / DC load Lac / DC power is supplied to dc, and DC power sources WTG, PV, FC and DC power from storage battery B are used for both AC and DC via the three-winding electronic transformer 3 when the storage battery B is fully charged or when the commercial AC power supply Utility is out of power Supply to the load Lac / dc, replenish the power from the fuel cell FC when the discharge of the storage battery B is proceeding, and AC power from the commercial AC power supply Utility to the AC / DC load Lac / dc at night and midnight power supply time In addition to the supply, the battery B is charged B by the bidirectionality and the AC / DC conversion function of the three-winding electronic transformer 3.

  Here, with respect to voltage fluctuation of the commercial AC power supply Utility, voltage adjustment is possible by pulse width modulation (PWM) control or pulse phase modulation (PPM) control of the modulation / demodulation semiconductor switches SW1 and SW2, and the commercial AC power supply Utility and DC A stable load voltage can be supplied with respect to fluctuations in the power sources WTG, PV, and FC, and at the same time, charging with night / midnight power is possible through the modulation / demodulation semiconductor switches SW1 and SW3.

  In the embodiment of FIGS. 5 and 6 described above, the circuit configuration is such that the AC power or DC power is switched by the contacts CT1, CT2, CT3 of the AC relay RL to supply power to the AC / DC load Lac / dc. The energy of the wind power generator WTG, the solar power generator PV, and the fuel cell FC is consumed on the load side without causing reverse flow (system connection) to the commercial AC power source via the storage battery B.

[Embodiment]
7 and 8 each show one embodiment of the invention of this application. In the embodiment shown in FIGS. 7 and 8, a reverse power flow is possible by directly connecting the storage battery B and the bidirectional DC-DC converter Conv. Currently, it is not allowed to reverse power flow at night and midnight in domestic power sales contracts, but reverse power flow is permitted for wind power generation and solar power generation. Is unknown, but from a purely technical point of view, all reverse flows are possible.

  In this embodiment, first, until the storage battery B reaches full charge by the DC power sources WTG, PV, and FC, the AC power from the commercial AC power supply Utility is used, and in FIG. 7, the bidirectional DC-DC converter Conv and the two windings are used. In FIG. 8, it is supplied to the AC dedicated load Lac via the three-winding electronic transformer 5 without going through the wire electronic transformer 4. Single-phase full-wave rectification of DC power sources WTG, PV, FC and DC power from storage battery B by half-cycle sine wave modulation of bidirectional DC-DC converter Conv when battery B is fully charged or commercial AC power supply is powered down Two pieces constituting the modulation / demodulation semiconductor switch SW3 connected to the storage battery side of the high-frequency transformer HFT of the two-winding electronic transformer 4 (FIG. 7) and the three-winding electronic transformer 5 (FIG. 8) after being converted into the waveform Alternatively, a modulation / demodulation semiconductor switch in which the high-frequency modulation phases of two pairs (four in total) of unidirectional semiconductor switches (not shown) are alternately reversed every half cycle of the commercial frequency and connected to the load side of the high-frequency transformer HFT A sine wave AC output is demodulated by SW2 and supplied to an AC dedicated load Lac. When the discharge of the storage battery B proceeds, power is supplied from the fuel cell FC. In the night / midnight power supply time period, AC power from the commercial AC power supply Utility is supplied to the AC dedicated load Lac, and the two-winding electronic transformer 4 (FIG. 7) and the three-winding electronic transformer 5 (FIG. 8). The battery B is charged by using both the bidirectional and AC / DC conversion function and the step-up high power factor rectification operation during charging of the bidirectional DC-DC converter Conv. Further, when the storage battery B is nearly fully charged at the time of light load and the commercial AC power supply Utility is not a power failure, the DC power is supplied to the two-winding electronic transformer 4 (FIG. 7) and the three-winding electronic transformer 5 (FIG. 8). Is converted into alternating current using the bidirectional transmission characteristics of the energy, and the power is automatically phase-synchronized to the commercial alternating current power source for reverse power flow.

  Here, the driving method of the bidirectional DC-DC converter Conv in the embodiment of FIG. 7 will be described more specifically with reference to FIGS. 9 and 10. FIG. 9 shows an example of inverter operation in the case of charging at night / midnight power or the like, and FIG. 10 shows a reverse power flow from the storage battery B to the AC / DC load Lac / dc or the commercial AC power supply Utility.

  In both figures, the switches S7 and S8 and the diodes D7 and D8 constituting the bidirectional DC-DC converter Conv (see FIG. 7) are unified with circuit element symbols in FIGS. Other symbols are the same as those in FIGS. The modulation / demodulation semiconductor switch SW3 (see FIG. 7) on the storage battery side in the two-winding electronic transformer 4 is actually two unidirectional semiconductor switches S5 and S6 or a bridge as illustrated in FIG. Thus, it can be configured by two pairs (four in total) of unidirectional semiconductor switches (not shown). Further, the load-side modulation / demodulation semiconductor switch SW2 (see FIG. 7) can be composed of two switches S3 and S4 as illustrated in FIG.

  In the case where the modulation / demodulation semiconductor switch SW3 on the storage battery side is constituted by two unidirectional semiconductor switches S5 and S6, the unidirectional semiconductor switches S5 and S6 (see FIG. 13) are driven with a modulated wave drive phase every half cycle of the commercial frequency. When the switches S3 and S4 (see FIG. 13) on the load side and the commercial AC power supply side are sinusoidal AC, the two-phase half-wave DC is applied to both ends of the capacitor C6 of the bidirectional DC-DC converter Conv. An output voltage 6 is generated (see FIGS. 9 and 13). Then, the switch S8 in FIG. 9 is driven by a normal boost type power factor correction IC (PFC-IC), while the switch S7 is stopped and the storage battery B is charged with the energy stored in the choke coil CH through the diode D7. To do. Since the charging voltage of the storage battery B is a step-up operation, a voltage higher than the maximum output amplitude of the two-winding electronic transformer 4 is generated, and sufficient charging is possible.

  On the other hand, in the case of an inverter operation that generates a sine wave alternating current from the storage battery B, as shown in FIG. 10, the switch S7 is driven by a sine wave modulated PWM signal, and is composed of a choke coil CH and a capacitor C6. A two-phase half-wave or single-phase full-wave rectified output 6 is generated on the filter output side. This output is high-frequency modulated (10 k to 50 kHz) by the unidirectional semiconductor switches S5 and S6 (see FIGS. 7 and 13) of the modulation / demodulation semiconductor switch SW3. At this time, the switches S3 and S4 of the modulation / demodulation semiconductor switch SW2 (FIG. 7, FIG. 13), the unidirectional semiconductor switches S5 and S6 (see FIG. 7 and FIG. 13) invert the drive phase of the modulation pulse every half cycle of the commercial frequency so as to be a sine wave. In this way, the sine wave AC output can be taken out to the output side of the two-winding electronic transformer 4, that is, the load side and the commercial AC power source side.

  Also, using the three-winding electronic transformer 5 shown in FIG. 8, the AC power supply Utility, the AC dedicated load Lac, and the storage battery B system are completely insulated using the three-winding electronic transformer 5 shown in FIG. The high frequency transformer HFT can perform an envelope modulation operation at a sine wave commercial AC frequency, and a conventional AC dedicated load Lac can be used for all loads.

  In addition, although the above embodiment is a thing at the time of combining all three, the wind power generator WTG, the solar power generation device PV, and the fuel cell FC, even when only one of them is used, arbitrary 2 Needless to say, the invention of this application can be applied even when two are combined, and an equally excellent distributed power supply system can be realized.

  Hereinafter, the invention of this application will be described in more detail with reference examples and examples.

[Reference Example 1]
FIG. 11 shows a more specific reference example of the reference embodiment of FIG. Since the codes used are the same as those in FIG. 5, only the added codes will be described here.

  First, TM is a timer for AC / DC power feeding and night / midnight power charging, and is controlled by the control circuit CONT-2. CONT-1 is a control circuit for the wind turbine generator WTG. When the wind turbine generator WTG is alternating current, it is rectified like an automobile generator, and when it is direct current, it is a generally known control circuit that adjusts the voltage as it is. S3 and S4 are bidirectional semiconductor switches. As shown in the enlarged view in the figure, two unidirectional semiconductor switches are used as back-to-back connections to perform both AC / DC switching operations. S5 to S8 are unidirectional semiconductor switches, D5 to D8 are built-in or external diodes, C1 to C6 are capacitors, and CH is a choke coil. N2 to N4 are windings of the high frequency transformer HFT.

  In the reference example of FIG. 11, the unidirectional semiconductor switches S5, S6, and S7 are stopped during AC power supply from the commercial AC power supply Utility, and the capacitor C6 is connected through the bidirectional semiconductor switches S3 and S4, the high-frequency transformer HFT, and the diodes D5 and D6. A DC voltage is generated at both ends. The DC voltage is adjusted by the unidirectional semiconductor switch S8 and the diode D7, so that the storage battery B can be charged. At the same time, AC power is supplied to the AC / DC load Lac / dc. Charging from commercial AC power supply Utility, mainly solar power generation during the day and wind power generation regardless of time of day, can be subordinate or zero. In the event of a power failure of the commercial AC power supply Utility, the AC relay RL is restored to immediately switch to DC power supply from the DC power sources WTG, PV, FC and the storage battery B, and DC power is supplied to the load side through the two-winding electronic transformer 2. The AC / DC load Lac / dc continues to operate. At this time, only the unidirectional semiconductor switch S8 stops operating, and the unidirectional semiconductor switch S7 and the diode D8 control the DC voltage, that is, step-down adjustment. Further, the discharge of the storage battery B can be performed by operating the fuel cell FC.

  The above explanation is for a case where the power failure time of the commercial AC power supply Utility is long. However, when the storage battery B reaches full charge even when there is no power failure, the switch SW is turned off by the timer TM according to the command of the control circuit CONT-2. By switching to direct current power supply, distributed power supply using natural energy and fuel cells can be realized.

[Reference Example 2]
FIG. 12 shows a more specific reference example of the reference embodiment of FIG. In the reference example of FIG. 12, as described above, the electronic transformer has three windings to insulate each power source from the load and further stabilize the fluctuation of the commercial AC power source Utility by PWM or PPM control. The outline of the operation of the three-winding electronic transformer 3 in this case is as follows.

  FIGS. 15A, 15B, and 15C are waveform diagrams for explaining the outline of the operation of the three-winding electronic transformer 3, respectively. The waveform on the left side in FIG. 15A shows the AC input terminal voltage of the three-winding transformer 3 after the input commercial AC voltage has passed through the filter F1. This input waveform is subjected to high-frequency ring modulation as shown in the center portion of FIG. 15A by a half bridge circuit composed of C1, C2, S1, and S2, and is applied to the primary winding N1 of the high-frequency transformer HFT. Now, when the number of turns of the secondary winding N2 is the same as the number of turns of the primary winding N1, the secondary winding is formed by a half bridge (in this case, operating as a voltage doubler circuit) composed of S3, S4, C3, and C4. A voltage twice as large as the voltage generated at N2 is demodulated. In this case, the drive timing of the switches is assumed to be driven at the same timings S1 and S3, S2 and S4. That is, the high-frequency modulation / demodulation technique reproduces the original sine wave AC waveform as it is on the demodulation side, and only the transformer is reduced in size and weight by high-frequency modulation, and the efficiency is improved as compared with a commercial transformer. At this time, it goes without saying that the high-frequency alternating current generated in the windings N3 and N4 can be rectified by the diodes D5 and D6 and the storage battery B can be charged in parallel by the bidirectional DC-DC converter Conv.

  Next, at the time of a power failure of the commercial AC power supply Utility or when the storage battery B is fully charged, high-frequency rectangular wave signals are generated by the push-pull inverter circuit by the windings N3 and N4 of the high-frequency transformer HFT and the semiconductor switches S5 and S6. However, the rectangular wave voltage generated in the winding N2 by S3 and S4 at this time becomes a direct current having a double voltage value by the voltage doubler circuit, and direct current power is supplied to the AC / DC load Lac / dc. That is, an electronic transformer operating by high frequency modulation / demodulation can convert a voltage regardless of whether it is a direct current or a direct current.

  FIG. 15B illustrates the voltage of the high frequency transformer HFT when a DC input is applied to the windings N3 and N4 at the center. FIG. 15C shows an example of adjusting the load side voltage by performing known PWM control on the S3 and S4 switches on the secondary winding side. Although the case of AC modulation / demodulation has been illustrated, it goes without saying that the same control is possible in the case of DC input.

  In addition, if the compressed fuel Fuel (mainly hydrogen) for the fuel cell FC is prepared and stored by the compressor COMP at the time of light load as a part of the load, it can be used for private power generation and electric vehicles. It is also useful for reducing environmental impacts, leveling load fluctuations, and improving the environment in preparation for the age of clean engines.

[Example]
FIGS. 13 and 14 show more specific examples of the embodiments of FIGS. 7 and 8, respectively, and eliminate the restrictions on the AC / DC load Lac / dc in FIGS. Emphasis is placed on compatibility with existing AC-dedicated equipment, and at the same time, a reverse power flow from the DC source through the electronic transformer to the commercial AC power supply Utility side is also possible. FIG. 14 shows a case in which a DC power source WTG, PV, FC and a storage battery B are connected via a three-winding electronic transformer 5. This is a case where the commercial AC power supply Utility and the AC dedicated load Lac are mutually insulated and connected.

  A major difference compared to FIGS. 11 and 12 is that the unidirectional semiconductor switches S5 and S6 operate during charging and discharging. Further, as shown in FIGS. 9 and 10, in the bidirectional DC-DC converter Conv, the battery voltage and the two-phase half-wave or single-phase full-wave rectified output 6 are converted into the forward / reverse bidirectional, and the unidirectional semiconductor switch In S5 and S6, AC modulation or demodulation conversion is performed, and the two-winding electronic transformer 4 and the three-winding electronic transformer 5 are always operated with only the AC modulation component. As a result, an AC output can always be taken out from the AC dedicated load side regardless of whether AC power supply or DC power supply is used.

  In order to realize this operation, for example, as illustrated in FIGS. 16A and 16B, the drive pulse phases of the switches S1 to S6 of the three-winding electronic transformer 5 are set to the positive half cycle and negative of the commercial AC power supply Utility. By alternately reversing during the half-cycle period, v1 and v2 always operate with an AC sine waveform, and the DC circuit v3 terminal always generates single-phase full-wave or two-layer half-wave DC input / output. The change in the magnetic flux of the three-winding electronic transformer 5 can always perform the AC modulation operation illustrated in FIG.

  In the case of the two-winding transformer 4 of FIG. 13, it corresponds to the case where there is no N1 in the example of FIG. 16, and it goes without saying that other operations are exactly the same.

  In any case, bidirectional transmission of power energy between two or three sets of input / output terminals of the two-winding electronic transformer 4 and the three-winding electronic transformer 5 is possible from direct current to alternating current of several hundred hertz. Is greatly different from the commercial power supply voltage device, and this is a basic feature of the system configuration of the present invention.

  Furthermore, another feature is that reverse power flow from the storage battery side to the commercial AC power supply side can be performed through the two-winding electronic transformer 4 and the three-winding electronic transformer 5 as long as there is no power failure of the commercial AC power supply Utility. Become. In this case, it goes without saying that an inverter operating oscillator in the event of a power failure is incorporated.

  Of course, the invention of this application is not limited to the above-described embodiments and examples, and various details are possible.

  As described above in detail, according to the invention of this application, a combination of a natural energy system power having a large variation factor and a stable power such as midnight power or a fuel cell can be commonly used at a usage rate close to 100%. A new distributed power supply system that can supply stable power to a load via a device, increase the price / performance ratio of the entire system, promote the spread of distributed power supply and save energy is provided.

It is a diagram that classifies the suitability of AC / DC power supply compatibility of conventional home appliances when AC / DC energy sources are used in a distributed power supply system in a low-voltage distribution system. FIG. 6 is a diagram showing a conventional example of solar power generation and wind power generation when an AC / DC energy source is directly supplied to a load in a low-voltage distribution system. It is a figure for demonstrating an example at the time of connecting a power feeding system and AC / DC load for both according to invention of this application. It is the figure which showed the reference embodiment of invention of this application. It is the figure which showed another reference embodiment of invention of this application. It is the figure which showed another reference embodiment of invention of this application. It is the figure which showed one Embodiment of invention of this application. It is the figure which showed another one Embodiment of invention of this application. FIG. 8 is a diagram for explaining the operation of the bidirectional DC-DC converter in the embodiment of FIG. 7. It is a figure for demonstrating operation | movement of the bidirectional | two-way DC-DC converter in embodiment of FIG. It is the figure which showed the reference example of invention of this application. It is the figure which showed another reference example of invention of this application. It is the figure which showed further one Example of invention of this application. It is the figure which showed another one Example of invention of this application. It is a figure for demonstrating the operation | movement outline | summary of a three winding electronic transformer. It is a figure for demonstrating the direct current | flow conversion operation | movement principle of a three-winding electronic transformer.

Explanation of symbols

Lac / dc AC / DC dual load Lac AC dedicated load
Utility Commercial AC power supply WTG Wind turbine generator PV PV generator FC Fuel cell B Storage battery
Conv Bidirectional DC-DC converter S7, S8 Unidirectional semiconductor switch D7, D8 Diode C5, C6 Capacitor CH Choke coil 1 Charger CHG
2 Two-winding electronic transformer 2a, 2b Bidirectional input / output terminal HFT High-frequency transformer N2-N4 Winding F2 Filter SW2, SW3 Modulation / demodulation semiconductor switch S3, S4 Bidirectional semiconductor switch S5, S6 Unidirectional semiconductor switch D5, D6 Diode C3, C4 Capacitor 3 Three-winding electronic transformer 3a, 3b, 3c Bidirectional input / output terminal HFT High frequency transformer N1-N4 Winding F1, F2 Filter SW1-SW3 Modulation / demodulation semiconductor switch S1-S4 Bidirectional semiconductor switch S5, S6 Unidirectional semiconductor switch D5, D6 Diode C1-C4 Capacitor 4 Two-winding electronic transformer 4a, 4b Bidirectional input / output terminal HFT High-frequency transformer N2-N4 Winding F2 Filter SW2, SW3 Modulation / demodulation semiconductor switch S3, S4 Bidirectional semiconductor Switch S5, S6 Unidirectional semiconductor Switch D5, D6 Diode C3, C4 Capacitor 5 Three-winding electronic transformer 5a, 5b, 5c Bidirectional input / output terminal HFT High-frequency transformer N1-N4 Winding F1, F2 Filter SW1-SW3 Modulation / demodulation semiconductor switch S1-S4 Bi-directional Semiconductor switch S5, S6 Unidirectional semiconductor switch D5, D6 Diode C1-C4 Capacitor 6 Single-phase full-wave or 2-phase half-wave DC output voltage D1-D4 Diode SW switch RL AC relay CT1, CT2, CT3 AC relay contact TM Timer CONT-1 Wind power generation control device CONT-2 Distributed power supply control device T Terminal plate COMP Compressor Fuel Fuel for fuel cell AC AC DC DC
Ic charge current
I INV Inverter current IB Battery current EB Battery voltage

Claims (3)

With or without a bidirectional DC-DC converter and a two-winding electronic transformer using at least one of a wind power generator, a solar power generator, and a fuel cell, a storage battery, and a commercial AC power source A distributed power supply system that performs distributed power supply to a dedicated AC load,
Wind power generators, solar power generators, and fuel cells are DC power sources in which each rated power voltage is unified with the rated voltage of the storage battery.
The two-winding electronic transformer has two bidirectional input / output terminals for both AC and DC, and has a high-frequency transformer and a modulation / demodulation semiconductor switch provided on the storage battery side and the load side.
One bidirectional input / output terminal of the two-winding electronic transformer is connected to the output side of the DC power source, and the other bidirectional input / output terminal is connected in a T shape between the commercial AC power supply and the AC dedicated load. And
Until the storage battery reaches full charge by the DC power source, supply AC power from the commercial AC power source to the AC dedicated load without going through the bidirectional DC-DC converter and the two-winding electronic transformer,
When the storage battery is fully charged or when the commercial AC power supply fails, the DC power from the DC power source and storage battery is converted into a single-phase full-wave rectified waveform by half-cycle sine wave modulation of a bidirectional DC-DC converter, Two windings are used to reverse the high frequency modulation phase of two or two pairs of unidirectional semiconductor switches constituting the modulation / demodulation semiconductor switch provided on the storage battery side of the high frequency transformer of the electronic transformer alternately every half cycle of the commercial frequency. Demodulated by a modulation / demodulation semiconductor switch provided on the load side of the high-frequency transformer of the electronic transformer, extracted the sine wave AC output and supplied to the AC dedicated load,
When the discharge of the storage battery progresses, power is supplied from the fuel cell,
In the night / midnight power supply time period, AC power from a commercial AC power source is supplied to the AC dedicated load, and the bidirectional and AC / DC conversion function of the two-winding electronic transformer and the bidirectional DC-DC converter Charge the storage battery using the boost type high power factor rectification operation at the time of charging.
When the storage battery is almost fully charged at light load and the commercial AC power supply is not out of power, the DC power is converted to AC by the energy bidirectional transmission characteristics of the two-winding electronic transformer and automatically phase synchronized to the commercial AC power supply side. The distributed power supply system is characterized by the reverse power flow. Using an at least one of a wind power generator, a solar power generator, and a fuel cell, a storage battery, and a commercial AC power source, to a dedicated AC load via a bidirectional DC-DC converter and a three-winding electronic transformer A distributed power supply system that performs distributed power supply of
Wind power generators, solar power generators, and fuel cells are DC power sources in which each rated power voltage is unified with the rated voltage of the storage battery.
The three-winding electronic transformer has three bidirectional input / output terminals for both AC and DC, and has a high-frequency transformer and a modulation / demodulation semiconductor switch provided on the commercial AC power supply side, storage battery side and load side,
The DC power source and the storage battery, the commercial AC power source and the AC dedicated load are mutually insulated and connected by the three-winding electronic transformer.
Until the storage battery is fully charged by the DC power source, supply AC power from the commercial AC power supply to the AC dedicated load via the three-winding electronic transformer,
When the storage battery is fully charged or when the commercial AC power supply fails, the DC power from the DC power source and the storage battery is converted into a single-phase full-wave rectified waveform by half-cycle sine wave modulation of a bidirectional DC-DC converter, and then three windings Three windings alternately reverse the high frequency modulation phase of two or two pairs of unidirectional semiconductor switches constituting the modulation / demodulation semiconductor switch provided on the storage battery side of the high frequency transformer of the electronic transformer every half cycle of the commercial frequency Demodulated by a modulation / demodulation semiconductor switch provided on the load side of the high-frequency transformer of the electronic transformer, extracted the sine wave AC output and supplied to the AC dedicated load,
When the discharge of the storage battery progresses, power is supplied from the fuel cell,
In the night / midnight power supply time period, AC power from a commercial AC power supply is supplied to the AC dedicated load, and the bidirectional and AC / DC conversion function of the three-winding electronic transformer and the bidirectional DC-DC converter Charge the storage battery using the boost type high power factor rectification operation at the time of charging.
When the storage battery is near full charge at light load and the commercial AC power supply is not out of power, the DC power is converted to AC using the bidirectional energy transmission characteristics of the three-winding electronic transformer, and automatically switched to the commercial AC power supply side. A distributed power supply system characterized in that reverse power flow is performed in phase synchronization.   3. The distributed power supply system according to claim 1, wherein compressed hydrogen for fuel cells can be stored.

Images