JP5539094B2 - Emergency power supply - Google Patents

Description

  The present invention relates to an emergency power supply device having a capacitor.

  Conventionally, as a voltage sag compensator using a capacitor as a power source, power is normally supplied from the commercial power source to the load through a high-speed cutoff switch, and the capacitor is charged from the commercial power source through the inverter at the rated voltage. When an instantaneous drop occurs, there is one that opens a high-speed cutoff switch instantaneously and supplies power stored in a capacitor to a load via an inverter (see Patent Document 1).

JP 2006-74903 A

  Capacitors in emergency power supply devices such as the voltage sag compensator as described above are always held at a rated voltage of several hundred volts at maximum in preparation for voltage sag. However, the capacitor has a property that the life is shortened as the charging voltage is increased. For example, when the charging voltage per cell is increased by 0.1 V, the life is halved. . In addition, since the leakage current increases as the cell voltage of the capacitor increases, there is a problem in that power loss increases due to charging at the rated voltage.

  The present invention has been made in order to solve the above-described problems, and provides an emergency power supply apparatus with little deterioration of a capacitor.

The emergency power supply apparatus according to the present invention is connected between a commercial power source and a load, and normally supplies power from the commercial power source to the load. Power supply device, comprising a capacitor control device for controlling charge and discharge of a capacitor, and this capacitor control device has an average cell voltage of a capacitor of 0.4 V per cell rather than an average of 2.7 V that is a rated voltage. The first mode is maintained at a voltage level lower than 0.2V from the first, and the second mode is maintained based on the emergency prediction signal to maintain the capacitor at the rated voltage level.

  According to the present invention, it is possible to obtain an emergency power supply device that can shorten the time for holding the capacitor at the rated voltage as much as possible, can reduce the deterioration of the capacitor, and exhibit a desired function.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the emergency power supply device which concerns on Embodiment 1 of this invention. It is a figure which shows the time chart of the driving | running condition when a power failure occurs in the emergency power supply device which concerns on Embodiment 1 of this invention. It is a figure which shows the time change of a commercial power source, a load, a capacitor, and a generator at the time of a power failure occurring in the emergency power supply device according to Embodiment 1 of the present invention. It is a block diagram which shows the emergency power supply device which concerns on Embodiment 2 of this invention.

Embodiment 1 FIG.
1 to 3 show an emergency power supply apparatus according to Embodiment 1 for carrying out the present invention. FIG. 1 is a diagram showing the configuration, and FIG. 2 is an operating situation when a power failure occurs. FIG. 3 is a diagram showing changes over time in commercial power, load, capacitor, and generator when a power failure occurs.

  As shown in FIG. 1, the emergency power supply device 1 is installed between a commercial power supply 8 and a load 15, and a power failure detection circuit 9 that detects an instantaneous drop or a power failure of the commercial power supply 8, Alternatively, when a power failure is detected, a relay circuit 10 that disconnects the commercial power supply 8, an AC / DC converter 11 that converts AC power supplied from the power supply 8 into DC power, the converter 11, and an AC load 15 a Between the converter 11 and the DC load 15 b and converted by the converter 11. The inverter 13 is provided between the converter 11 and reconverts the DC power converted by the converter 11 into predetermined AC power. And a DC / DC converter 14 for reconverting the electric power into predetermined direct-current power. The emergency power supply 1 controls the capacitor 2 that stores power supplied from the commercial power supply 8, the bidirectional DC / DC converter 3 that charges and discharges the capacitor 2, and the charge / discharge voltage of the converter 3. And a capacitor control device 4 for monitoring the holding voltage of the capacitor 2, and a communication means 5 for transmitting an emergency prediction signal issued from a command device 6 located outside the emergency power supply device 1 to the control device 4, A generator 17 having a 100 KW class diesel engine that generates power during a power failure and supplies the load 15 and the capacitor 2; a smoothing capacitor 12 that smoothes the power supplied from the generator 17 and the capacitor 2 to the load 15; And a control device 7 for controlling the entire emergency power supply device 1.

  The above emergency prediction signal is a signal issued when an emergency in which an instantaneous power failure or power failure occurs in the emergency power supply device 1 is predicted. In this case, it is known that an instantaneous power failure or a power failure has occurred during a lightning strike, so that it is issued when a thunderstorm approaches the management area of the commercial power supply 8 where the emergency power supply device 1 is installed. In many cases, thunderstorms occur in the summer evening for about an hour, and such thunderstorms occur at a frequency of about 50 times throughout the year, so the capacitor 2 is likely to be discharged annually. Through about 50 hours and the other about 8000 hours are unlikely to discharge.

The capacitor 2 has a power storage capacity of 1 MW 1.2 seconds, that is, 1.2 MJ, and is composed of a total of 320 capacitor cells in which 20 cell modules are connected in series. This capacitor cell is a 1200 F class electric double layer capacitor, and its effective storage power is about 3.5 kJ. Moreover, the rated voltage of this electric double layer capacitor is 2.7V, and it uses it in the voltage range of 1.2-2.7V.
When the voltage of the capacitor 2 decreases to ½, the same power cannot be extracted unless the current is doubled. However, the maximum allowable current of the bidirectional DC / DC converter 3 is required to greatly increase the current. In order to increase the maximum allowable current, the switching elements of the converter 3 must be parallelized, which increases the cost. Also, the wiring loss increases in proportion to the square of the current. Therefore, normally, stored power of 1.2 V or less is not taken out.

Next, the operation will be described.
In normal times, AC power supplied from the commercial power supply 8 is transmitted to the AC / DC converter 11 through the power failure detection circuit 9 and the relay circuit 10 and converted to DC power. This direct current power is transmitted to the inverter 13 and the DC / DC converter 14, reconverted to alternating current power by the inverter 13, supplied to the alternating current load 15 a, and then reconverted to direct current power by the DC / DC converter 14. It is supplied to the load 15b.

The power supplied from the commercial power supply 8 is transmitted to the bidirectional DC / DC converter 3, and the output voltage of the converter 3 is adjusted by the capacitor control device 4 to be fed to the capacitor 2. Is charged to an average of 2.5V. After charging, the capacitor control device does not recharge until the cell voltage of the capacitor 2 decreases to an average of 2.3V or less by self-discharge, and charges again to an average of 2.5V when the cell voltage decreases to an average of 2.3V or less. 4 controls the bidirectional DC / DC converter 3.
The mode in which the capacitor 2 is held at a voltage level lower than the rated voltage in this way is hereinafter referred to as a first mode.

Next, when a thunderstorm approaches the management area of the commercial power supply 8 where the emergency power supply 1 is installed and the risk of lightning strikes increases, an emergency prediction signal is issued from the external commanding device 6 and the communication means 5 is connected. Is transmitted to the capacitor control device 4. Upon receiving this, the capacitor control device 4 controls the bidirectional DC / DC converter 3 (point A) so that the cell voltage of the capacitor 2 becomes 2.7V on average as shown in FIG. Prepare for a momentary drop or a power failure (point B).
Thus, the mode in which the capacitor 2 is held at the rated voltage level is hereinafter referred to as a second mode.

  When a lightning strike occurs and a power failure occurs (point C), the power failure detection circuit 9 detects this, cuts off the relay circuit 10 and disconnects the commercial power supply 8 and starts supplying power from the capacitor 2 to the load 15. . At this time, as shown in FIG. 3, the power source of the generator 17 is turned on, the engine of the generator 17 is started 2 seconds after the occurrence of the power failure (point D), and 8 seconds after the occurrence of the power failure through the idle operation state ( Power generation is started at point E), power supply to the load 15 and the capacitor 2 starts, and the capacitor 2 is partially charged. Immediately after the start of power generation, the generator 17 is operated at the maximum output, and then the transition from the maximum output operation to the high efficiency operation is started (point F), and the high efficiency operation is continued after the transition (point G). At this time, when the power consumed by the load 15 is larger than the power supplied by the generator 17, the capacitor 2 is discharged, and the power supplied from the generator 17 and the power supplied from the capacitor 2 are combined. Then, the load is leveled by supplying it to the load 15. When the commercial power supply 8 recovers (point H), power supply from the commercial power supply 8 to the load 15 and the capacitor 2 is resumed. At this point, the generator 17 stops generating electricity and is maintained in the idle operation state again. Then, after the charging of the capacitor 2 is completed and the mode is shifted to the second mode (point I), the generator 17 is stopped (point J).

  Thereafter, when the risk of an instantaneous voltage drop or power failure is reduced and the emergency is resolved, a signal indicating normal time is issued from the external command device 6 and transmitted to the capacitor control device 4 via the communication means 5. The Receiving this, the capacitor control device 4 switches from the second mode to the first mode.

Note that the above-mentioned voltage drop often ends within 2 seconds, and when a voltage drop within 2 seconds occurs, power is supplied only from the capacitor 2 to the load 15, and the generator 17 turns on the power. Just do not start the engine.
In addition, even when a voltage sag or power failure occurs while controlling the capacitor 2 to the first mode, the stored power of the capacitor 2 charged with an average cell voltage of 2.5V is an average cell voltage of 2.7V. This corresponds to about 80% of the stored power charged in step 1, and 1 MW is output for 1.0 second, that is, 1 MJ, so that the function can be fully exhibited.

  According to the present embodiment, during normal times, the capacitor 2 is controlled to the first mode that maintains a voltage level lower than the rated voltage, and when an emergency in which an instantaneous drop or power failure occurs is predicted, Since the control is performed so as to switch to the second mode in which the capacitor 2 is held at the rated voltage level in accordance with the emergency prediction signal issued based on the emergency prediction, the risk of instantaneous voltage drop or power failure is low. A part of time is held at a low voltage level to reduce the deterioration of the capacitor 2, and an emergency power supply device capable of performing a desired function by holding at a rated voltage level during a time when there is a high risk of instantaneous voltage drop or power outage is obtained. it can. In addition, power loss due to leakage current can be reduced.

In the first mode, after charging the cell voltage of the capacitor 2 at an average of 2.5 V,
Recharging is not performed until the average voltage drops to 2.3 V or less due to self-discharge, and when the average voltage drops to 2.3 V or less, charging is performed again to an average of 2.5 V. Less power loss can be further reduced. Furthermore, since the life is doubled when the cell voltage of the capacitor 2 is lowered by 0.1V, by holding the cell voltage at an average of 2.5V, the cell voltage at the average voltage of 2.7V is maintained. In comparison, the lifetime can be quadrupled.

Further, in the event of a power failure, the power supplied from the generator 17 and the power supplied from the capacitor 2 are combined and supplied to the load 15 so that the load is leveled. Forcibly fluctuating operation of the generator 17 can be suppressed and deterioration of the generator 17 can be prevented. Furthermore, since the conditions of the exhaust gas catalyst of diesel engines can be kept constant by suppressing the variable operation, the generation of soot and CO due to incomplete combustion, and the generation of NO _X due to excess air are suppressed, and the exhaust gas is kept clean and noise is reduced. Can be small.

  In addition, the instantaneous drop due to lightning often ends within 2 seconds, and even if the generator 17 is started, the possibility of supplying power to the load 15 is low. Therefore, after 2 seconds, the engine is started and the standby state is set to 8 seconds. By starting the power generation later, it is possible to prevent the life of the diesel engine generator 17 from deteriorating due to the start-up, and it is possible to speed up the engine start-up slightly by securing the standby state.

In addition to thunderstorms, an instantaneous drop or power failure occurs when there is a possibility of affecting the commercial power supply 8, such as the approach of thunderclouds or typhoons, an earthquake, or a fire in the area where the emergency power supply 1 is installed. Therefore, even in such a case, an emergency prediction signal is issued from the external command device 6 to switch from the first mode to the second mode.
In areas where solar cells have become popular, there is a high risk of instantaneous voltage drop or power outage. Efforts have been made to maintain the stability of the grid by grid connection called micro grid or smart grid, but if there is a cloud in the clear sky in the time zone after noon when the sun is in the south, power generation will occur if the sun is hidden in the cloud. When power drops sharply and the sun comes out of the clouds, the generated power recovers rapidly, so the output fluctuation of the solar cell increases, and the system may not stabilize and there is a risk of instantaneous voltage drop or power failure . Even in such a case, an emergency prediction signal is issued from the external command device 6 to switch from the first mode to the second mode.

  Further, the external command device 6 can be installed in the manufacturer of the emergency power supply device 1. In this way, the manufacturer monitors the local weather forecast as a service to the user, and issues an emergency forecast signal when there is a risk of a thunderstorm in the area where the device 1 is installed. Then, it is possible to switch from the first mode to the second mode via a radio, a mobile phone, the Internet, or the like. The external command device 6 may be installed and operated by the user of the emergency power supply device 1 and issues an emergency prediction signal based on weather information provided by a weather forecast service company or the like. Accordingly, the first mode may be switched to the second mode. Alternatively, the operating status of the emergency power supply device 1 may be transmitted to the external command device 6 via the communication means 5 and this information may be used for maintenance of the power supply device 1.

  When charging / discharging the capacitor 2, the charging current may be made smaller than the discharging current. Since the capacitor has a property of generating heat during charging and absorbing heat during discharging, and a property of reducing the lifetime by half when its temperature rises by 7 ° C., in this way, the temperature rise associated with charging of the capacitor 2 is increased. It can be suppressed and deterioration can be prevented.

  Further, in normal times, when the power consumption of the load 15 becomes higher than a specified value, the power stored in the capacitor 2 may be supplied to the load 15. By doing in this way, the increase in contract power can be prevented and a great user merit can be obtained. The power consumption of the load 15 exceeds the contract power in many cases due to the operation of the air conditioner around noon in summer, which is several days throughout the year, and the time is 1 to 2 hours. Furthermore, the electric power stored in the capacitor 2 may be supplied to the load 15, and the generator 17 may be activated to supply the electric power from the generator 17 to the load 15. By doing in this way, even if the power consumption of the load 15 greatly exceeds the specified value, it is possible to prevent an increase in contract power.

  When the power consumption of the load 15 exceeds the amount of power supplied by combining the power supplied from the generator 17 and the power supplied from the capacitor 2 at the time of a power failure, the control device 7 causes the inverter 13 and the DC The output voltage of the DC converter 14 may be controlled so as to decrease the supply voltage to the load 15. In the case of the 100V system, there are loads that reduce power consumption as the voltage drops, and loads that become inoperable when the voltage drops below 90V. By doing so, the load is reduced and operation is possible even when the voltage drops. Can continue to use the load. Further, a boost converter may be provided for a load that cannot tolerate a power failure, and when the supply voltage to the load decreases, the supply voltage may be boosted by this boost converter to continue the operation.

  In the event of a power failure, if the power consumption of the load 15 exceeds the amount of power supplied by combining the power supplied from the generator 17 and the power supplied from the capacitor 2, the power supply to the DC load 15b is changed to AC. You may make it give priority to the electric power supply to the load 15a. By doing in this way, the reliability of the load which can operate | move with DC electric power, such as LED lighting and a personal computer, can be improved. Furthermore, the user's convenience is increased because the option of connecting the load to continue operation even in an emergency to the DC power distribution in advance is born.

Embodiment 2. FIG.
FIG. 4 is a diagram showing a configuration of an emergency power supply device 1B according to Embodiment 2 for carrying out the present invention. In the first embodiment, the configuration in which the emergency power supply device 1 is installed between the commercial power supply 8 and the load 15 is shown. However, as shown in FIG. 4, the emergency power supply device 1B is replaced with the commercial power supply 8 and the solar cell 18. And the load 15 may be installed. The emergency power supply device 1B includes a DC / DC converter 19 that converts the power supplied from the solar battery 18 and a diode 20 that is connected to the converter 19 and prevents a reverse flow of power to the solar battery 18. Are controlled by the control device 7, and other configurations are the same as those of the first embodiment.

Next, the operation will be described.
The power supplied from the solar cell 18 is converted into predetermined direct current power by the DC / DC converter 19 and then combined with the power supplied from the commercial power source 8. The combined power is supplied to the load 15 via the inverter 13 and the DC / DC converter 14 and is also supplied to the capacitor 2 via the bidirectional DC / DC converter 3.

  The electric power supplied from the solar cell 18 changes suddenly depending on the weather conditions, and if this rapid change flows back to the commercial power supply 8 as it is, there is a risk that the harmonic component will have an adverse effect and a malfunction may occur. The capacitor control device 4 controls the capacitor 2 to the first mode, and when the electric power generated by the solar cell 18 is suddenly reduced, supplies the reduced electric power from the capacitor 2 to the load 15. When the power generated by the battery 18 suddenly increases, the output power of the solar battery 18 is leveled by controlling the capacitor 2 to charge this increased power.

  According to the present embodiment, the capacitor 2 is leveled by charging and discharging the sudden change in the output power of the solar cell 18, so that the influence of the sudden change on the commercial power supply 8 of the solar cell 18 is mitigated. , There are significant benefits for power companies.

  In addition, also when charging / discharging the output power of the solar cell 18 to the capacitor 2, the charging current may be made smaller than the discharging current. By doing in this way, the temperature rise accompanying charge of the capacitor 2 can be suppressed and deterioration can be prevented.

  In each of the above-described embodiments, a configuration in which 320 cells of electric double layer capacitors are connected in series as the capacitor 2 is shown. However, a lithium ion capacitor, a hybrid capacitor, a lithium ion battery, and a lithium ion capacitor are provided inside the cell. The same effect can be obtained even if various capacitors such as a composite capacitor are used. Moreover, although the structure which uses the capacitor 2 and the generator 17 as an emergency power supply of an emergency power supply device was shown, in addition to this, various batteries, such as a lithium ion battery, a lead storage battery, a nickel hydrogen battery, and a sodium sulfur battery May be provided in the emergency power supply device to serve as an emergency power source. Moreover, as a generator, although the structure using the generator 17 provided with the diesel engine which is a direct current generator was shown, it is good also as a structure which connects alternating current generators, such as an induction machine and a synchronous machine, to an alternating current side, This AC generator may be connected to the DC side via a converter.

DESCRIPTION OF SYMBOLS 1, 1B Emergency power supply device 2 Capacitor 3 Bidirectional DC / DC converter 4 Capacitor control device 8 Commercial power supply 15 Load 17 Generator 18 Solar cell

Claims (5)

An emergency power supply device connected between a commercial power supply and a load, normally supplying power from the commercial power supply to the load, and supplying power from the capacitor to the load in the event of an emergency when the commercial power supply is instantaneously reduced or blackout,
A capacitor control device for controlling charge and discharge of the capacitor;
The capacitor control device controls the cell voltage of the capacitor to a first mode in which the cell voltage is maintained at a voltage level lower by 0.4V to 0.2V per cell than an average of 2.7V, which is a rated voltage , An emergency power supply apparatus that controls to a second mode in which the capacitor is held at the rated voltage level based on a time prediction signal.   The emergency power supply device according to claim 1, wherein the emergency prediction signal is generated based on lightning information.   3. The emergency power supply device according to claim 1, further comprising a generator that supplies power to the load and the capacitor when power supply from the commercial power supply to the load is interrupted.   The emergency power supply apparatus according to any one of claims 1 to 3, further comprising a solar battery that feeds power to the load and the capacitor.   The capacitor control device charges the capacitor with a sudden increase in the power generated by the solar cell and discharges the rapid decrease in the power generated by the solar cell from the capacitor to the load at normal times. The emergency power supply apparatus according to claim 4, wherein the emergency power supply apparatus is controlled as follows.

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