JP2007060796A - Power buffer device system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power buffer device system wherein there are provided both a load leveling function and an uninterruptible power supply function and further the charging and discharging life of a power storage facility does not degrade so much. <P>SOLUTION: The power buffer device system includes: an alternating current-to-direct current converter that converts alternating-current power into direct-current power between a commercial system and a direct-current bus; and an inverter that converts direct-current power into alternating-current power between the direct-current bus and a load. The power buffer device system further includes: an instantaneous-type power buffer connected with the direct-current bus through a first double-way DC/DC converter; a sustained-type power buffer connected with the direct-current bus through a second double-way DC/DC converter in parallel with the instantaneous-type power buffer; and a control device that controls the first double-way DC/DC converter and the second double-way DC/DC converter. When a load abruptly changes, the control device inputs/outputs the changed portion to the instantaneous-type power buffer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power buffer device system having an uninterruptible power supply function and a load leveling function.

Conventionally, contract with the power company for the merits of the power company by leveling the generated power in the power system day and night by discharging the power stored in the secondary battery at night during peak power demand. For example, there is a system that returns electricity to consumers because the electricity charge at night falls to about one-third of the daytime charge.
In addition, for the purpose of recommending power saving, a system is used in which the electricity charge is lower as the contracted power is smaller. Peak cut operation is also performed to keep contract power low.
And the electric power peak cut power supply device which performs both peak cut operation and load leveling operation is proposed. However, if the secondary battery is repeatedly charged and discharged rapidly, the life of the secondary battery is significantly impaired, and the secondary battery needs to be frequently replaced. It is said that the possible number of charge / discharge cycles when the secondary battery is rapidly charged / discharged is about 1000 times. If the charge / discharge depth is reduced to about 10%, a charge / discharge life of nearly 10,000 times can be secured (see, for example, Patent Document 1).
In view of this, an output stabilization device that stabilizes system linkage by charging and discharging using an electric double layer capacitor instead of a secondary battery has been proposed. It is said that the electric double layer capacitor has a charge / discharge life of 100,000 times or more and a life of 10 years or more (see, for example, Patent Document 2).

Also, in recent years, the use of solar cells for homes and buildings has become widespread, storing late-night power and making it an uninterruptible power supply, and discharging it during daytime hours to use it for power conversion and storage of solar power Has been proposed (see, for example, Patent Document 3).
In addition, a hybrid power supply system that combines midnight power storage and solar cell power storage is disclosed (see, for example, Patent Document 4).

JP 2002-271994 A Japanese Patent Laid-Open No. 2004-282872 JP 2002-315231 A JP 2001-177995 A

However, when a secondary battery is used in a conventional power storage system that uses midnight power, the battery capacity is 10 times the amount of discharge power required to reduce the charge / discharge depth and delay the deterioration of the charge / discharge life. There is a problem that it is necessary to provide a secondary battery.
In addition, when an electric double layer capacitor is used, the energy density per weight of the electric double layer capacitor is as low as 1/10 of that of the secondary battery, and the electric double layer capacitor has a weight nearly 10 times that of the secondary battery. There is a problem that it is necessary to prepare.
In addition, the conventional power storage system that combines a solar battery or wind power generator with an uninterruptible power supply is mainly used as an uninterruptible power supply, so the state of charge of the secondary battery is maintained close to full charge, There is a problem that it can hardly contribute to load leveling.
In addition, there is a problem that it is a high-cost system such as incorporating four charge / discharge converters in order to shorten the charging depth and extend the life of the secondary battery.

  An object of the present invention is to provide a power buffer device system that has both a load leveling function and an uninterruptible power supply function, and delays the deterioration of the charge / discharge life of the power storage device.

  A power buffer device system according to the present invention includes an AC / DC converter that performs AC / DC conversion of power between a commercial system and a DC bus, and an inverter that performs DC / AC conversion of power between the DC bus and a load. In the system, an instantaneous power buffer connected to the DC bus via a first bidirectional DC / DC converter, and a second bidirectional DC / DC converter in parallel with the instantaneous power buffer And a control device for controlling the first bidirectional DC / DC converter and the second bidirectional DC / DC converter, the control device comprising: When the load changes rapidly, the change is input / output to / from the instantaneous power buffer.

  The effect of the power buffer device system according to the present invention is that a sudden power-type power buffer responds to a sudden change in load, thereby avoiding sudden charge / discharge in the sustained-power type power buffer. It is possible to reduce the deterioration of the charge / discharge life.

Embodiment 1 FIG.
1 is a schematic diagram showing an overall configuration of a power buffer device system according to Embodiment 1 of the present invention. FIG. 2 is a functional block diagram of the control apparatus according to the first embodiment.
A power buffer device system 1 according to Embodiment 1 of the present invention is a system that receives AC power of a commercial system 2 and supplies power to a normal load 3 and an emergency load 4 by a normal inverter power supply method. Here, the normal load 3 is a load that is allowed to be interrupted when the commercial system 2 is cut off. The normal load 3 has a voltage drop compensation value of about 15%. When the voltage drops below 20%, the operation is interrupted and no power is consumed.

  On the other hand, the emergency load 4 here is a load that is not allowed to interrupt the operation when the commercial system 2 fails, and is, for example, a load related to security, computer, important lighting, elevators, and the like. Therefore, the emergency load 4 has a boosting function for boosting the voltage when the supplied voltage is low, and the operation is continued even if a low voltage, for example, 70V is supplied. Although it is assumed that AC power of 70V is supplied to the emergency load 4, the operation of the normal load 3 is interrupted when the voltage is 80V or lower, so that at least the voltage is changed to 80V or lower when the commercial system 2 fails. Thus, the operation of the emergency load 4 alone can be continued.

The power buffer device system 1 according to the first embodiment converts the AC power of the commercial system 2 into DC power once, then converts it back to desired AC power, and feeds the normal load 3 and the emergency load 4 at all times. For the instantaneous power-type power buffer 11 capable of instantaneous charge and discharge, the load leveling function, and the uninterruptible power supply function to cope with instantaneous load fluctuations in the power supply unit 10, the normal load 3 and the emergency load 4 Sustainable power buffer 12 capable of storing a large amount of power, a first bidirectional DC / DC converter 14 that converts power between the DC bus 13 of the inverter power supply unit 10 and the instantaneous power buffer 11 at all times. A second bidirectional DC / DC converter 15 that converts power between the DC bus 13 of the inverter power supply unit 10 and the sustaining power buffer 12 and controls the entire system. It is equipped with a control device 16.
Further, the power buffer device system 1 uses the power failure detection circuit 8 that detects a power failure occurring in the commercial system 2 between the commercial system 2 and the constant inverter power supply unit 10 and the inverter power supply unit 10 when the power failure is detected. A double-cut relay 9 that is disconnected from the system 2 is connected.

  The constant inverter power supply unit 10 includes an AC / DC converter 18 that bi-directionally converts power between the commercial system 2 and the DC bus 13, a DC bus 13 that transmits the converted DC power to DC, and a DC input from the DC bus 13. An inverter 19 for converting electric power into predetermined AC power is provided.

The instantaneous power type power buffer 11 has a large power that can be charged and discharged per unit time per weight (hereinafter referred to as power density) but a small energy density per weight (hereinafter referred to as weight energy density). For example, an electric double layer capacitor, an electrolytic capacitor, a ceramic capacitor, or a film capacitor. The electric energy W stored in these is expressed as W = 1/2 CV ² from the capacitance C and the terminal voltage V. When the voltage V = 0V, the charging electric energy is 0%, and when the voltage V = the rated voltage, charging is performed. The amount of power becomes 100%. And repeating charging / discharging between 0% of charging electric energy and 100% of charging electric energy is called charging / discharging in the charging / discharging depth of 100%. And this instantaneous power type electric power buffer 11 has a small decrease in the capacitance C that is seen when charging / discharging at a charge / discharge depth of 100% is repeated, and a decrease in the amount of stored electric power is small. It is said that the charge / discharge life has been reached when the reduction in the amount of stored electric power is reduced by a predetermined rate, for example, 20%.

  Among the above power storage devices, an electric double layer capacitor having a high weight energy density is desirable, and has a charge / discharge life of 100,000 times or more at a charge / discharge depth of 100% and a life of 100,000 hours or more at 40 ° C. Therefore, it has a weight energy density nearly 100 times that of an electrolytic capacitor having the highest weight energy density among other power storage devices. Moreover, the main constituent materials are carbon and aluminum, which are inexpensive and environmentally friendly materials.

The sustaining power buffer 12 is a power storage device having a large weight energy density but a low power density, and is a secondary battery such as a lead storage battery, a lithium ion battery, a NaS battery, or a nickel metal hydride battery. These secondary batteries have a maximum amount of stored power that can be stored. Since the charge / discharge power is limited by the second bidirectional DC / DC converter 15, deterioration of the charge / discharge life can be delayed.
Note that a sustaining power type electric double layer capacitor may be used as the sustaining power buffer 12. Even if the electric double layer capacitor is made of the same material, both an instantaneous force type and a continuous force type can be formed depending on the thickness of the electrodes (positive electrode and negative electrode).

In general, if the electrode thickness is 0.1 mm or less, the electrical resistance is small, and charging / discharging can be performed with high efficiency even if charging / discharging is performed instantaneously within 10 seconds. However, since the weight energy density is small, a lot of energy cannot be stored. As such an instantaneous type electric double layer capacitor, a product CR having a capacitance C and an internal resistance R is preferably 2ΩF or less, and an energy conversion efficiency of 95% or more can be maintained by charge / discharge of one-quarter. It is.
On the contrary, if the electrode thickness is 0.4 mm or more, the electrical resistance becomes high, and charging / discharging with high efficiency cannot be performed instantaneously, but since the weight energy density is large, the charging / discharging efficiency is high over several tens of minutes. Can save a lot of energy. As such a long-lasting electric double layer capacitor, the product CR of the capacitance C and the internal resistance R is preferably 200ΩF or more. If charging / discharging is performed for about 100 minutes, the energy conversion efficiency is 95% or more. Is preserved. By using nanogate carbon instead of conventional activated carbon as the carbon material, a weight energy density comparable to that of a lead storage battery or a nickel metal hydride battery can be obtained.

  The first bidirectional DC / DC converter 14 keeps the charging power amount of the instantaneous power type buffer 11 at around 50% of the charging capacity, and when it exceeds 50%, the stored power is stored in the sustaining power buffer 12. Alternatively, the DC bus 13 is discharged. Moreover, when it falls below 50%, electric power is replenished from the continuous power buffer 12 or the DC bus 13. In this way, if the charging power amount of the instantaneous power buffer is maintained at around 50% of the charging capacity, the change can be absorbed sufficiently even if the load suddenly increases or decreases.

As shown in FIG. 2, the control device 16 has a timer 21, and based on the time counted by the timer 21, the AC / DC converter 18 and the second bidirectional DC are used in the late-night time zone when the electricity rate is low. DC / DC converter 15 is controlled to charge system power to sustaining power buffer 12 at a constant predetermined current, and AC / DC converter 18 and second bidirectional DC are used in the morning time when the power consumption increases rapidly. A load leveling unit 22 that controls the DC converter 15 to discharge from the sustaining power buffer 12 with a constant predetermined current and purchase power to the commercial system 2 is provided.
The control device 16 controls the first bidirectional DC / DC converter 14 when the loads of the normal load 3 and the emergency load 4 change suddenly, and charges and discharges the change in the instantaneous power buffer 11. Thus, a sudden load fluctuation mitigation unit 23 is provided for mitigating a change in voltage at the DC bus 13.

  When the power failure detection circuit 8 detects a power failure in the commercial system 2, the control device 16 discharges DC power from the sustaining power buffer 12 to the DC bus 13 by the second bidirectional DC / DC converter 15. Then, the inverter 19 is controlled to convert the DC power into AC power having a voltage of 100 V and feed the normal load 3 and the emergency load 4. Then, after the elapse of a predetermined time period, the inverter 19 is controlled after 10 seconds in this case, and the uninterruptible power supply unit 24 that converts the DC power into AC power having a voltage of 70 V and supplies the emergency load 4 is provided. Yes.

Thus, when the commercial system 2 fails, the AC voltage from the inverter 19 is lowered to 70V, so that the normal load 3 does not consume power but is consumed only by the emergency load 4 that can operate at 70V. Accordingly, less power is discharged from the sustaining power buffer 12, and the power can be supplied longer. And it becomes possible to use the emergency load 4 for a long time even in the event of a power failure, and it is possible to secure time for evacuation or activation of private power generation. Which device is used as the emergency load 4 varies depending on the use of the power buffer device system 1 such as home use, building use, or factory use.
In this way, since the commercial grid 2 is discharged from the sustaining power buffer 12 when a power failure occurs, the uninterruptible power that can be supplied to the emergency load 4 is always supplied to the sustaining power buffer 12 for a predetermined time. Competence is stored.

FIG. 3 is a schematic diagram showing the flow of power controlled by the power buffer device system 1 when the commercial system 2 is normal and during a power failure. In order from the top of FIG. 3, power lines of the instantaneous power buffer 11, the normal load 3, the emergency load 4, the sustaining power buffer 12, and the commercial grid 2 are shown, and an arrow connecting them indicates the direction of power flow. Show.
When the commercial system 2 is normal, power is supplied from the commercial system 2 to the normal load 3 and the emergency load 4 by the inverter power supply unit 10 at all times. In addition, sudden load fluctuations generated in the normal load 3 and the emergency load 4 are input to and output from the instantaneous power buffer 11. Accordingly, the power supply amount at the power receiving point with the commercial system 2 is less changed in a short time, which is advantageous for the power company who is the operator of the commercial system 2.

  At the time of a power failure in the commercial system 2, the commercial system 2 is always disconnected from the inverter power supply unit 10 until the elapse of 10 seconds from the detection of the power failure, the DC bus 13 is charged by the continuous power buffer 12, and the voltage of the inverter 19 is Is maintained at 100V, so that the normal load 3 and the emergency load 4 are supplied from the sustaining power buffer 12. In many cases, the instantaneous drop in the commercial system 2 usually recovers within 1 second, and a power failure of 10 seconds or less may automatically recover. Thus, the inverter 19 supplies the power of 100V voltage for 10 seconds. When it is done, consumers do not recognize that there was an instantaneous drop or power outage. As described above, when the voltage drop is instantaneous, the normal load 3 also continues to operate, and thus has a function for preventing a voltage sag.

  When the power failure of the commercial system 2 continues for more than 10 seconds, the voltage of the inverter 19 is reduced to 70V, so that only the emergency load 4 is supplied from the sustaining power buffer 12. The sudden load fluctuation in the emergency load 4 is input / output to / from the instantaneous power buffer 11. In this way, by changing the inverter 19 to 70V output, it is possible to secure electric power necessary for evacuation in the event of a power failure exceeding 10 seconds. This is because the power consumption of the sustaining power buffer 12 is reduced, and the operation of the normal load 3 other than the emergency load 4 is stopped, so that the user cannot immediately recover from the power failure. Recognizing this, it is possible to secure the time necessary for evacuation, flashlight, candle and match arrangement, telephone contact, etc.

  If the power failure detection circuit 8 and the double-cut relay 9 are omitted, the normal load 3 continues to operate and consumes power, so that the user is not aware of the power failure at all. There is a problem that the stored power of the buffer 12 is exhausted immediately and a real power failure occurs.

FIG. 4 is a schematic diagram showing the flow of power controlled by the power buffer device system 1 in the midnight time zone and the morning time zone.
In the midnight time zone when the commercial system 2 is normal, power is supplied from the commercial system 2 to the normal load 3 and the emergency load 4 by the inverter power supply unit 10 at all times. In addition, the continuous power buffer 12 is charged with a constant predetermined current from the DC bus 13 of the inverter power supply unit 10 at all times. In addition, sudden load fluctuations in the normal load 3 and the emergency load 4 are input to and output from the instantaneous force type power buffer 11. This midnight time zone is four hours from 1:00 am to 5:00 am where the midnight charge is set lower than the daytime charge.

  In the morning time zone when the commercial system 2 is normal, the sustaining power buffer 12 is discharged to the DC bus 13 by the second bidirectional DC / DC converter 15 with a constant predetermined current. When the electric power discharged from the continuous power buffer 12 is larger than the electric power fed to the normal load 3 and the emergency load 4, the AC / DC converter 18 reversely flows into the commercial system 2. In addition, sudden load fluctuations in the normal load 3 and the emergency load 4 are input to and output from the instantaneous force type power buffer 11. This morning time zone is two hours from 7:00 am to 9:00 am when the power consumption increases rapidly, and is a time zone corresponding to the operation of thermal power generation.

  In this way, by releasing the power stored in the midnight hours in the morning hours when the power demand increases rapidly, the slope of the increase in power demand becomes gentler, and the increase in the amount of power generated by thermal power generation It becomes easy to meet the increase in If the amount of power generated by thermal power generation is not in time for the power demand, a wide-area power outage may occur, but the power company is also advantageous because it is mitigated by the discharge from the sustaining power buffer 12.

FIG. 5 is a diagram illustrating a change of power in each part of the power buffer device system 1 according to the first embodiment over one day.
The power generation amount of the electric power company in FIG. 5 represents the national average, and although the summer is the largest, there is almost no change in the trend of the day in the four seasons. The amount of power generation is the smallest at around 5:00 in the early morning. Next, there is a morning time zone 44 in which the power demand rapidly increases in the morning. The peak time zone 46 of the first power generation amount is at noon. The peak power generation time zone 50 appears around 2pm. From noon to 2:00 pm, it is a lunch break, and it is a noon time zone 49 where power consumption temporarily decreases. Since the output of nuclear power plants cannot be increased or decreased frequently, nuclear power shares about 40% of the power generated during peak hours, and the rest is mainly generated by thermal power.
In addition to the power generation peak time periods 46 and 50, the morning time period 44 in which the sudden increase in power demand is a problem for electric power companies. This is because the amount of thermal power generation must be increased in accordance with this rapid increase in power demand.

  The load in FIG. 5 is the power consumption in a home or building, and shows a pattern of consuming power in a general home that does not have a solar power generation system. As we get up, we turn on lighting, TV, air conditioner, and use microwave oven, vacuum cleaner and washing machine, so the load will increase rapidly. Near noon, power consumption increases due to lunch preparation, television, and air conditioning. Moreover, after the power consumption reaches a peak after the evening when the family is together, the power consumption rapidly decreases with going to bed. Depending on the usage status of home appliances, the load may change rapidly in seconds or minutes.

The lasting power type buffer 12 is charged over time for four hours from midnight to 5:00 when the midnight power charge (less than one third of the daytime) is set. Although depending on the type of secondary battery used, rapid discharge in about 1 hour is possible, but rapid charge degrades the charge / discharge life, so 100% charge / discharge takes 2 hours or more. It is common to do it.
The power stored using the late-night power is discharged at a constant current to the DC bus 13 in 2 hours from 7 am to 9 am, and the surplus power is supplied to the normal load 3 and the emergency load 4. Reverse power flow to commercial system 2. By doing in this way, the rapid increase in power demand can be mitigated. For example, if 1 million households discharge 1 kWh of electricity, the total amount of electricity reaches 1 million kWh, and this is repeated every day. This can be used to reduce the amount of thermal power generation. . In other words, the power supply side such as an electric power company is worth buying at the daytime power rate. The sustaining power buffer 12 in which the amount of uninterruptible power is stored is prepared in the event of a power failure of the commercial system 2 and is stored so that the nighttime power is fully charged again at midnight the next day. .

In this way, the user charges the sustaining power buffer 12 with midnight power, so that the power demand increases during the time when the general power demand decreases, and the commercial power system 2 can be stabilized. There is a merit of the side.
Furthermore, since the time zone for selling power to the power company is a 2-hour time zone from 7:00 am to 9:00 am, the user obtains the difference in the charge between midnight power and daytime power as a merit.

  The instantaneous power type buffer 11 absorbs sudden changes in the unit of seconds and minutes of the normal load 3 and the emergency load 4, so that there is a great merit on the electric power company side that the sudden change is not transmitted to the commercial system 2. is there. In addition, there is a merit for the user that charging / discharging of the sustaining power buffer 12 becomes gentle and deterioration of the charging / discharging life is reduced.

Embodiment 2. FIG.
FIG. 6 is a schematic diagram showing an overall configuration of a power buffer device system according to Embodiment 2 of the present invention. FIG. 7 is a functional block diagram of the control device according to the second embodiment.
The power buffer device system 1B according to the second embodiment of the present invention corresponds to the power generated by the solar cell 30 in the power buffer device system 1 according to the first embodiment (hereinafter referred to as solar power generation power). The difference is that the function is added, and the rest is the same, so the same reference numerals are given to the same parts and the description is omitted.
In the power buffer device system 1B according to the second embodiment, as shown in FIG. 6, the DC bus 13 of the inverter power supply unit 10 is always the first bidirectional DC / DC converter 14 and the second bidirectional DC / DC converter. 15 and a relay circuit 31. The relay circuit 31 is opened when the photovoltaic power is charged into the sustaining power buffer 12, and when the sustaining power buffer 12 is charged from the commercial system 2 and from the sustaining power buffer 12 to the DC bus 13. Closed when discharging.
In the power buffer device system 1 </ b> B, the diode 32 is provided so as to be interposed between the solar cell 30 and the second bidirectional DC / DC converter 15.

  As shown in FIG. 7, the control device 16B according to the second embodiment opens the relay circuit 31 in a predetermined time zone, charges the solar power generated power to the sustaining power buffer 12, and relays it in the predetermined time zone. The circuit 31 is closed and the AC / DC converter 18 and the second bidirectional DC / DC converter 15 are controlled to discharge from the sustaining power buffer 12 to the DC bus 13 with a constant predetermined current and flow backward to the commercial system 2. A solar power generation processing unit 34.

The time zone in which the solar power charged in the sustaining power buffer 12 is discharged to the commercial grid 2 with a certain predetermined current is a time zone in which the power generation amount of the commercial grid 2 in the morning or afternoon is at a peak. Specifically, as shown in FIG. 10, the first peak time zone 46 is one hour from 11:00 am to noon, and the second peak time zone 50 is 2 pm to 3 pm One hour until the time.
On the other hand, the time zone in which the photovoltaic power is charged in the sustaining power buffer 12 is the time zone immediately before the discharge time zone, specifically, for the time zone 46 of the first peak, It is 2 hours from 9 am to 11 am, and for the second peak time zone 50, it is 2 hours from noon to 2 pm.

Further, the sudden load fluctuation mitigating unit 23B controls the first bidirectional DC / DC converter 14 to the instantaneous force type power buffer 11 when the photovoltaic power is rapidly changed when the relay circuit 31 is open. The change in the solar power applied to the second bidirectional DC / DC converter 15 is reduced by charging / discharging the change.
The sudden load fluctuation mitigating unit 23B controls the first bidirectional DC / DC converter 14 when the normal load 3 and the emergency load 4 are suddenly changed when the relay circuit 31 is closed, thereby generating an instantaneous force type. Charge / discharge the change in the power buffer 11 and charge / discharge the change in the instantaneous power buffer 11 by controlling the first bidirectional DC / DC converter 14 when the photovoltaic power generation changes suddenly. To reduce the change in the DC bus 13.

FIG. 8 shows the flow of power controlled by the power buffer device system 1B according to the second embodiment when charging the photovoltaic power and discharging the photovoltaic power stored in the sustaining power buffer 12. It is a schematic diagram which shows.
When the photovoltaic power is charged to the sustaining power buffer 12, the second bidirectional DC / DC converter is disconnected from the DC bus 13, and the instantaneous power buffer 11 suddenly increases the photovoltaic power. Alleviate major changes. During this time, all of the photovoltaic power is stored in the sustaining power buffer 12 and is not supplied to the commercial system 2. Therefore, even if the sun hidden in the clouds comes out and the power generation amount suddenly increases, there is no concern that the harmonic component will affect the commercial system 2. Further, since the photovoltaic power is stored all the time, and the fluctuation of the photovoltaic power is absorbed by the instantaneous power buffer 11, the charge / discharge life of the sustaining power buffer 12 is maintained. In other words, conventionally, it is possible to extend the life of the power storage device, which had to be replaced every three years, by repeating charging and discharging up to twice as long. Further, if the sustaining power buffer 12 is not a secondary battery but a sustaining electric double layer capacitor, the life can be further extended.

FIG. 9 is a schematic diagram showing the flow of power controlled by the power buffer device system 1B according to the second embodiment when a commercial power failure occurs when solar power is being charged.
Since the relay circuit 31 is open when the photovoltaic power is charged into the sustaining power buffer 12, when a power failure in the commercial system 2 is detected, the relay 9 is opened and the relay circuit 31 is closed. As in the case of the first embodiment, the AC power of 100 V is output from the inverter 19 for 10 seconds and the supply to the normal load 3 and the emergency load 4 is continued. Then, the AC power from the inverter 19 is By changing the voltage to 70V, it is possible to secure the power necessary for evacuation in the event of a power failure exceeding 10 seconds. At this time, since the photovoltaic power is supplied, it is possible to supply power during a power outage for a considerably long time in the daytime.

FIG. 10 shows a daily power change by the power buffer device system 1B according to the second embodiment.
Although the amount of solar power generation in FIG. 10 is in fine weather, it varies greatly depending on the weather, and the amount of power generation decreases drastically when hidden by clouds, and the amount of power generation recovers rapidly when the sun comes out of the clouds. . That is, there is a rapid change in units of seconds or minutes, and if the reverse flow flows into the commercial system 2 as it is, there is a possibility that the harmonic component has an adverse effect and a problem occurs. In addition, it is almost impossible for a power supplier such as an electric power company to predict the change in advance.

  Therefore, in the second embodiment, the instantaneous force type power buffer 11 absorbs a rapid change in seconds or minutes of the normal load 3 or the emergency load 4, and at the same time the seconds or minutes of the photovoltaic power generation. Absorbs sudden changes. As a result, the influence of a sudden change on the commercial system 2 is mitigated, and a great merit is produced for the electric power company. Further, the charging / discharging of the sustaining power buffer 12 is moderated, the charge / discharge life is improved, and there is a merit for the user.

  In the continuous power buffer 12 that has been discharged to the uninterruptible power, the photovoltaic power is stored while being separated from the DC bus 13, and the stored photovoltaic power is used as the power from 11:00 am to noon. The DC bus 13 is discharged in the first peak time zone 46 of demand. The power company avoids instability of the grid caused by the photovoltaic power because the photovoltaic power does not flow to the commercial grid 2 during the time when the power demand increases from 9:00 am to 11:00 am can do. Furthermore, in the first peak time zone 46, the electric power stored in the sustaining power buffer 12 is discharged at a constant predetermined current, so that the power supply from each home can be relied upon. . In addition, since the time zone from 9:00 am to 11:00 am is fixed and the weather in each region can be grasped, the total amount of power generation can be predicted relatively easily, so the thermal power generation amount can be reduced accordingly. .

In the two-hour time zone 49 from noon to 2 o'clock, the factories and office buildings enter the lunch break, so the demand for electricity drops slightly due to power savings in lighting. Although this time zone 49 is a time zone in which the efficiency of the solar cell is highest, even if power is directly supplied from the solar cell 30 to the commercial grid 2, there is no merit to the electric power company.
In such a system, the photovoltaic power is stored in the sustaining power buffer 12 and discharged in one hour from 2 pm to 3 pm, which is the second peak time zone 50 of power demand. , Peak power can be lowered and thermal power generation can be reduced.
In addition, like the time zone from 9:00 am to 11:00 am, the time zone from 0:00 pm to 2:00 pm is fixed, so it is possible to predict the total power generation by grasping the weather. is there. Therefore, some electric power companies are worth buying at the daytime electricity rate.

  In the three hours from 3:00 pm to 6:00 pm, in fact, even if the sun is tilted west, a considerable amount of power can be generated. However, even if solar power is supplied to the commercial grid 2 as it is during this time period, there is no merit for the electric power company. Therefore, the photovoltaic power is temporarily stored in the sustaining power buffer 12 and gradually discharged from the sustaining power buffer 12 in accordance with the load after 6:00 pm. For the user, there is an advantage that the amount of purchasing commercial power is reduced.

The time period during which the user sells power to the electric power company is a time zone 44 of 2 hours from 7 am to 9 am, a time zone 46 of 1 hour from 11 am to noon, from 2 pm to 3 pm The total of 4 hours in the 1 hour time zone 50 is basically.
Further, when the sustaining power buffer 12 is discharged to the DC bus 13, the photovoltaic power is supplied to the DC bus 13, but since the instantaneous power buffer 11 can alleviate a sudden change in the photovoltaic power. The commercial system 2 is not adversely affected.
In addition, it is possible to reduce the amount of power purchased from the commercial grid 2 by the photovoltaic power generated between 3 pm and 6 pm.

  In such a power buffer device system 1B, the continuous power buffer 12 and the instantaneous power buffer 11 are connected in parallel to the solar cell 30, respectively, and the solar power is charged in the continuous power buffer 12. Since the change in the photovoltaic power input to the sustaining power buffer 12 is mitigated by charging / discharging the instantaneous power buffer 11 with the sudden change in the photovoltaic power, the sustaining power buffer 12 Deterioration of the charge / discharge life can be delayed.

  In addition, although the power purchase price and the power sale price are set to be the same for solar power generation at present, if the number of solar cell panels increases and the unfavorable situation for power companies such as instability of grid power increases. Of course, it is estimated that the power selling price to the power company will be lower than the power purchasing price. However, in the power buffer device system 1B according to the second embodiment, the merit of the electric power company is great, and the user expands the merit including the charge difference between midnight power and daytime power.

Embodiment 3 FIG.
FIG. 11 is a schematic diagram showing an overall configuration of a power buffer device system according to Embodiment 3 of the present invention. FIG. 12 is a functional block diagram of the control apparatus according to the third embodiment.
As shown in FIG. 11, a power buffer device system 1C according to the third embodiment of the present invention generates power generated by the wind power generator 35 in the power buffer device system 1 according to the first embodiment (hereinafter referred to as wind power generation power). The functions corresponding to the above are different, and the others are the same. Therefore, the same reference numerals are added to the same parts, and the description is omitted.
In the power buffer device system 1 </ b> C according to the third embodiment, the diode 36 is provided so as to be interposed between the wind power generator 35 and the second bidirectional DC / DC converter 15.
Note that a sustaining power type double-layer capacitor is used as the sustaining power buffer 12C according to the third embodiment.

As illustrated in FIG. 12, the control device 16C according to the third embodiment is configured to charge the wind power generated in the sustaining power buffer 12C based on the wind power generated by the control device 16 according to the first embodiment. The difference is that the processing unit 37 is added, and the rest is the same, so the same reference numerals are given to the same parts and the description is omitted.
The wind power generation power processing unit 37 supplies the wind power generation power as it is to the DC bus 13 when the wind power generation power is smaller than the power output from the inverter 19, and the sustaining power when the wind power generation power is larger than the power output from the inverter 19. The mold power buffer 12 is charged.
Further, the abrupt load fluctuation mitigation unit 23C controls the first bidirectional DC / DC converter 14 when the wind power generation power changes abruptly, and charges and discharges the change in the instantaneous force type power buffer 11 to the second. The change in the wind power generated by the bidirectional DC / DC converter 15 is alleviated.
The sudden load fluctuation mitigating unit 23C controls the first bidirectional DC / DC converter 14 when the normal load 3 and the emergency load 4 are suddenly changed, and charges and discharges the change in the instantaneous force type power buffer 11. By doing so, the change in the DC bus 13 is relaxed.

FIG. 13 is a schematic diagram showing the flow of power controlled by the power buffer device system 1C according to the third embodiment of the present invention when the commercial system 2 is normal and a power failure occurs.
In the case of wind power generation as well as in the case of solar power generation in the second embodiment, during a power outage, as in the case of the first embodiment, after the supply of AC power having a voltage of 100 V is continued for 10 seconds, Since the power failure detection circuit 8 and the relay 9 are provided, the power necessary for evacuation can be secured in the event of a power failure exceeding 10 seconds by changing the voltage of the AC power from the inverter 19 to 70V. Become.

  In such a power buffer device system 1C, the sustaining power buffer 12C and the instantaneous power buffer 11 are connected in parallel to the wind power generator 35, respectively, and the wind power is charged in the sustaining power buffer 12C. By charging / discharging the instantaneous force type power buffer 11 with the rapid change in the wind power generation power, the change in the wind power input to the sustain power type buffer 12C is alleviated. Deterioration of discharge life can be delayed.

Moreover, since the sustaining power type electric double layer capacitor is used as the sustaining power buffer 12C, the deterioration of the charge / discharge life can be further delayed.
Furthermore, since wind power is supplied, it is possible to supply power during a power outage for a considerably long time.
In addition, even during a power outage at night, power can be supplied over a long period of time, such as a power source for lighting required by wind power generation.

It is a schematic diagram which shows the whole structure of the electric power buffer apparatus system concerning Embodiment 1 of this invention. 2 is a functional block diagram of a control device according to Embodiment 1. FIG. It is a schematic diagram which shows the flow of the electric power controlled by the electric power buffer apparatus system at the time of normal and a power failure of a commercial system. It is a schematic diagram which shows the flow of the electric power controlled by the electric power buffer apparatus system in the midnight time zone and the morning time zone. It is a figure which shows the change over 1 day of the electric power in each part of the electric power buffer apparatus system concerning Embodiment 1. FIG. It is a schematic diagram which shows the whole structure of the electric power buffer apparatus system concerning Embodiment 2 of this invention. 4 is a functional block diagram of a control device according to Embodiment 2. FIG. It is a schematic diagram which shows the flow of the electric power controlled by the power buffer apparatus system concerning Embodiment 2 when charging photovoltaic power and discharging the photovoltaic power stored in the sustaining power buffer. . It is a schematic diagram which shows the flow of the electric power controlled by the electric power buffer apparatus system concerning Embodiment 2 at the time of a power failure in a commercial system when charging photovoltaic power generation. It is a figure which shows the change over 1 day of the electric power in each part of the electric power buffer apparatus system concerning Embodiment 2. FIG. It is a schematic diagram which shows the whole structure of the electric power buffer apparatus system concerning Embodiment 3 of this invention. FIG. 9 is a functional block diagram of a control device according to a third embodiment. It is a schematic diagram which shows the flow of the electric power controlled by the electric power buffer apparatus system concerning Embodiment 3 of this invention when a commercial system is normal and a power failure occurs.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Electric power buffer system 2 Commercial system 3 Normal load 4 Emergency load 8 Power failure detection circuit 9 Relay 10 Constant inverter feeding part 11 Instantaneous power buffer 12 Continuous power buffer 13 DC bus , 14, 15 Bi-directional DC / DC converter, 16 controller, 18 AC / DC converter, 19 inverter, 21 timer, 22 load leveling unit, 23 rapid load fluctuation mitigating unit, 24 uninterruptible power supply unit, 30 solar cell, 31 Relay circuit, 32, 36 diode, 34 solar power generation processing unit, 35 wind power generator, 37 wind power generation power processing unit, 44 morning time zone, 46 first peak time zone, 49 daytime time zone, 50 Time zone for the second peak.

Claims (12)

In an AC / DC converter for AC / DC conversion of power between a commercial system and a DC bus, and a power buffer device system including an inverter for DC / AC conversion of power between the DC bus and a load,
An instantaneous power buffer connected to the DC bus via a first bidirectional DC / DC converter;
A sustaining power buffer connected to the DC bus via a second bidirectional DC / DC converter in parallel to the instantaneous power buffer;
A control device for controlling the first bidirectional DC / DC converter and the second bidirectional DC / DC converter;
With
The said control apparatus inputs / outputs the change part to the said instantaneous force type | mold electric power buffer when the said load changes rapidly, The electric power buffer apparatus system characterized by the above-mentioned.   2. The power buffer device system according to claim 1, wherein the sustaining power buffer is a secondary battery, and the instantaneous power buffer is an electric double layer capacitor.   The sustaining power buffer is an electric double layer capacitor whose product of internal resistance and capacitance is 200ΩF or more, and the instantaneous power buffer is an electric double layer whose product of internal resistance and capacitance is 2ΩF or less. The power buffer device system according to claim 1, wherein the power buffer device system is a capacitor.   2. The power buffer according to claim 1, wherein the control device controls the first bidirectional DC / DC converter so as to keep a power storage amount of the instantaneous power buffer at half of a charge capacity. Equipment system. The control device includes a timer,
The second bidirectional DC / DC converter is controlled so that the DC power of the DC bus is charged to the sustaining power buffer with a constant current in the midnight time zone, and the sustaining power is supplied in the morning time zone. 2. The power buffer device system according to claim 1, wherein the electric power is discharged from the power buffer to the DC bus at a constant current. Comprising a power failure detection circuit and a relay installed between the commercial system and the AC / DC converter,
The relay is opened by a power failure detection signal from the power failure detection circuit,
The said control apparatus controls the said inverter so that the voltage of the alternating current power output from the said inverter will be 80V or less after progress for a predetermined time, after receiving the said power failure detection signal. A power buffer device system to be described.   The power buffer device system according to claim 6, wherein the inverter supplies AC power to an emergency load that operates with AC power having a voltage of 80 V or less. A relay circuit that opens and closes the sustaining power buffer and the instantaneous power buffer with respect to the DC bus;
The sustaining power buffer and the instantaneous power buffer are connected in parallel to the solar cell,
The control device opens the relay circuit in a predetermined time zone, charges and discharges the sudden change in the power generated by the solar cell in the instantaneous power type buffer, and performs the relay in another predetermined time zone. 2. The power buffer device system according to claim 1, wherein a sudden change in the electric power generated by the solar cell is charged and discharged in the instantaneous force type power buffer by closing a circuit.   9. The power buffer device system according to claim 8, wherein the control device opens the relay circuit in the predetermined time period and charges the continuous power buffer with the power generated by the solar cell. .   9. The control device according to claim 8, wherein the relay circuit is closed at the other predetermined time period, and the electric power charged in the sustaining power buffer device is discharged to the DC bus at a constant current. Or the power buffer device system according to 9.   The other predetermined time zone is a time zone in which the power generation amount of the commercial system in the morning or afternoon is at a peak, and the predetermined time zone is immediately before the time zone in which the power generation amount of the commercial system is at a peak. The power buffer device system according to any one of claims 8 to 10, wherein the power buffer device system is in the following time zone. The sustaining power buffer and the instantaneous power buffer are connected in parallel to the wind power generator,
The control device charges the sustaining power buffer with the power generated by the wind power generator, and charges and discharges the sudden change power buffer with a sudden change in the power generated by the wind power generator. The power buffer device system according to claim 1.

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