JP2012151977A - Load leveling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load leveling system capable of leveling a daily load fluctuation of a specific electrical facility group with a simple facility configuration.SOLUTION: A load leveling system 1 for leveling power consumption of a specific electrical facility group 3 including a predetermined electric device 2A is provided in addition to an inverter device 9 which controls operation state of the electric device 2A on a supplied AC power. It includes an energy accumulating means 6 which is charged with a charging circuit 10 connected to a power source 4 that supplies power to the specific electrical facility group 3, and a control means 7 which, in the case where the power consumption of the specific electrical facility group 3 is larger than the power consumption of the specific electrical facility group 3 during charging of the energy accumulating means 6, opens a first power feeding circuit 11A that runs from the power source 4 to the inverter device 9, but closes a second power feeding circuit 12 that runs from the energy accumulating means 6 to the inverter device 9, so that the electric power of the energy accumulating means 6 is fed to the inverter device 9.

Description

  The present invention relates to a load leveling system.

  Along with the development of power storage technology, various types of electrical equipment have been developed for the purpose of suppressing daily load fluctuations in an electric power system (for example, see Patent Documents 1 to 3).

JP 2001-95180 A JP 2008-148443 A JP 2003-324848 A

  Many of the electrical equipment installed for the purpose of suppressing daily load fluctuations of the electric power system has a large capacity storage battery such as a NaS battery (Natrium-sulfur battery). Facilities such as AC / DC converters and system protection devices are provided. Consumer electrical equipment installed for the purpose of storing cheap midnight power and using it during the day is also small because many of the electrical equipment used on the consumer side assumes AC power. However, it is necessary to install an AC / DC converter or an AC system protection device.

  Then, this application makes it a subject to provide the load leveling system which can equalize the daily load fluctuation | variation of a specific electrical equipment group with a simple apparatus structure.

  In order to solve the above-described problems, the present invention provides a power storage unit in addition to an inverter device that controls the operating state of a predetermined electrical device with supplied AC power, and power consumption of a specific electrical equipment group including the predetermined electrical device. Is large, the power storage means was discharged.

  More specifically, a load leveling system that equalizes the power consumption of a specific group of electrical equipment including the predetermined electrical equipment in addition to an inverter device that controls the operating state of the predetermined electrical equipment with supplied AC power. A power storage means that is charged by a charging circuit connected from a power source that supplies power to the specific electrical equipment group; and the specific electrical equipment group when the power consumption of the specific electrical equipment group is charged by the power storage means. The first power supply circuit connected to the inverter device from the power source is opened, and the second power supply circuit connected to the inverter device from the power storage means is closed to connect the electricity of the power storage means to the inverter. Control means for supplying power to the apparatus.

  The load leveling system does not supply AC power and level the power consumption of a specific electrical equipment group, but is attached to various inverter devices installed in the specific electrical equipment group to store power. By supplying the electricity stored in the means to the inverter device as a direct current, the power consumption of the specific electrical equipment group is leveled. Since the inverter device converts direct current to alternating current, if the load leveling system is added to an existing or newly installed inverter device in a specific electrical equipment group, the power consumption of the load connected to the inverter device will be exceeded. The power consumption of the specific electrical equipment group can be leveled within a range that does not exist.

As a matter of course, the load leveling is realized by discharging the power storage means when the power consumption of the specific electrical equipment group is large, and charging the power storage means when the power consumption is small. In the control device, the power consumption of the specific electrical equipment group is more than the power consumption of the specific electrical equipment group at the time of charging the power storage means so that at least charging / discharging of the power storage means is performed under such a concept. Is larger, the first feeding circuit is opened and the second feeding circuit is closed to discharge the power storage means.

  In the case of the load leveling system, the inverter unit installed in the load of the specific electrical equipment group is simply provided with a system having a simple device configuration including the power storage unit and the control unit. The daily load fluctuation of the equipment group can be leveled.

  The control means closes the charging circuit and charges the power storage means at night time when the power consumption of the specific electrical equipment group is smaller than the daytime, and the power consumption of the specific electrical equipment group The first power supply circuit is opened and the second power supply circuit is closed and the electricity of the power storage means is supplied to the inverter device during the daytime when the power storage means is larger than the charging time. There may be.

  In many electrical equipment groups, the daily load fluctuation time zone of power consumption is almost constant, so the control means can change the daily load fluctuation of a specific electrical equipment group simply by switching the charging and discharging of the power storage means according to the time zone. Can be leveled.

  Moreover, the said control means may open and close said 1st electric power feeding circuit and said 2nd electric power feeding circuit based on the pattern of the daily load fluctuation | variation of the power consumption of the said specific electric equipment group.

  Since most of the electrical equipment groups have a daily constant fluctuation pattern of power consumption, the control means simply switches between charging and discharging the power storage means based on the daily load fluctuation pattern created in advance. The daily load fluctuation can be leveled.

  The control means may obtain the daily load fluctuation pattern from a wattmeter that measures power consumption of the specific electrical equipment group.

  If the above load leveling system is configured in this way, it can follow the daily load fluctuation pattern and time zone change of a specific electrical equipment group, so that the daily load fluctuation of a specific electrical equipment group can be further improved. It can be leveled appropriately.

  The power source is alternating current, and the inverter device is supplied with electric power of the power source converted from alternating current to direct current by a converter device and smoothed by a smoothing capacitor, and the power storage means converts alternating current to direct current. The battery may be charged by the charging circuit provided with a rectifier for conversion, and the second power feeding circuit may connect a circuit connecting the converter device and the inverter device and the power storage means.

  If the load leveling system is configured in this way, when the power source to the inverter device is switched from the converter device to the power storage means or from the power storage means to the converter device, the input power to the inverter device is reduced. Since voltage fluctuation is suppressed by the smoothing capacitor, there is no possibility of instantaneous voltage drop.

  Daily load fluctuations of a specific electrical equipment group can be leveled with a simple device configuration.

It is a block diagram of a group of electrical equipment on the premises equipped with a load leveling system. It is a table | surface which shows the pattern of a switch. It is the graph which showed the 1st pattern of daily load fluctuation of power consumption. It is the graph which showed the 2nd pattern of daily load fluctuation of power consumption. It is the graph which showed the 3rd pattern of the daily load fluctuation | variation of power consumption. It is a block diagram of the premise electric equipment group which concerns on the modification which provided the load leveling system side by side.

  Hereinafter, embodiments of the present invention will be described. The embodiment described below is an example of one aspect of the present invention, and the technical scope of the present invention is not limited to the following embodiment.

  FIG. 1 is a configuration diagram of a group of on-premises electrical equipment in which a load leveling system according to the present embodiment is installed. On-premise electric equipment group E (one aspect of the specific electric equipment group referred to in the present invention. The specific electric equipment group referred to in the present application may be the entire electric consumer (for example, the entire building such as a building). Or a smaller group of facilities (for example, a group of specific air-conditioning facilities) is a group of electrical facilities possessed by a specific power consumer such as a building, residence, factory, or plant. It consumes the power transmitted from the nuclear power plant, thermal power plant, hydroelectric power plant, and other various power plants through the transmission and distribution network. Here, description will be given below on the assumption that commercial buildings having an air conditioning system are applied as the on-premises electrical equipment group E. As shown in FIG. 1, the local electrical equipment group E includes a load group 3 constituted by a large number of loads (loads 2A to 2Z). In FIG. 1, the electric circuit is illustrated by one line, but the number of phases and the number of lines are not limited.

  The load group 3 receives AC power from a commercial power source 4 via a switch gear (so-called metacladder (metal clad switch gear), power center, control center, etc.) and cables that house a circuit breaker and a transformer in a cabinet. Receive supply. The load group 3 includes electrical facilities that consume electric power (for example, air conditioning facilities, lighting facilities, and computer facilities).

  Of the load group 3, the load 2 </ b> A (which is an aspect of the predetermined electric device in the present invention) is not a device that operates by directly receiving the power supplied from the commercial power supply 4 connected to the power system, A device that operates by receiving power whose frequency and voltage are adjusted by a frequency converter (hereinafter referred to as an inverter). That is, the load 2A is provided side by side with the inverter 5A that controls the operating state of the load 2A by adjusting the frequency and voltage of the supplied AC power. Examples of application of the load 2A include frequency adjustment of input power such as a compressor for an air conditioning refrigerator, a pump for circulating cooling water, and an AC electric motor for operating driving devices provided in industrial facilities. Applicable to any electrical equipment.

  The load leveling system 1 according to the present embodiment aims to level the daily load fluctuations of the electric power consumed in the on-site electrical equipment group E by additionally providing it in the existing inverter 5A. 6 (which is an aspect of the power storage means referred to in the present invention), a control device 7 (which is an aspect of the control means referred to in the present invention), and a rectifier 14 that rectifies an alternating current from the commercial power source 4 into a direct current using a diode. I have. The storage battery 6 is charged with electricity converted into direct current by the rectifier 14. However, it is also possible to newly install an inverter 5A in the premises electrical equipment group E in which the inverter 5A is not installed, and to additionally install the load leveling system 1. The inverter 5A for leveling the load leveling system 1 may be a general-purpose module product such as an IPM driver as long as the storage battery 6 can be connected to a DC line.

The inverter 5A includes a converter unit 8 that converts an alternating current into a direct current, and an inverter unit 9 that converts the direct current into an alternating current (which is an aspect of the inverter device in the present invention). The inverter unit 9 converts the direct current rectified by the above into an alternating current having an arbitrary frequency according to a request and supplies the alternating current to the load 2A. For example, if the load 2A is an electric fan for air conditioning, the inverter 5A adjusts the switching frequency so that the rotational speed of the fan becomes the rotational speed required by the control device of the air conditioning system. A smoothing capacitor (not shown) that smoothes the pulsation of the direct current is provided between the converter unit 8 and the inverter unit 9. The storage battery 6 may be connected to either the upstream side or the downstream side of the smoothing capacitor as long as it is connected between the converter unit 8 and the inverter unit 9.

  The storage battery 6 is a chargeable / dischargeable secondary battery. The type and number of storage batteries 6 are appropriately determined according to required storage capacity, budget, and the like. The storage battery 6 is appropriately selected from various batteries such as a lithium battery and an LL battery (control valve type lead storage battery).

The control device 7 is a control device including a CPU, a storage device, an input / output interface, a display device, and the like, and controls the load leveling system 1. More specifically, the control device 7 performs load leveling (peak shift) of the power consumption of the local electrical equipment group E based on the power consumption pattern of the local electrical equipment group E and the capacity of the storage battery 6. The remaining amount of the storage battery 6 can be specified based on a map in which the correlation between the open voltage of the storage battery 6 and the remaining battery amount is predetermined. The open voltage of the storage battery 6 is detected by a voltmeter or the like. The control device 7 switches the switch swA _A that opens and closes the first power supply circuit 11A connected from the commercial power source 4 to the inverter 5A based on the power consumption pattern of the premises electrical equipment group E, the remaining amount of the storage battery 6, and other various external signals. The switch swB that opens and closes the second power feeding circuit 12 connected from the storage battery 6 to the inverter 5A and the switch swC that opens and closes the charging circuit 10 connected from the commercial power supply 4 to the storage battery 6 are controlled.

The control device 7 controls the switches swA _A , swB, and swC with the following pattern. A control pattern of each switch executed by the control device 7 is shown in FIG. The controller 7, as shown in FIG. 2, when charging the battery 6 (electric storage mode), to turn on the switch swC and switches swA _A, to turn off the switch swB. In the case of power feeding from the battery 6 to the load 2A (discharge mode), it turns off the switch swC and switches swA _A, turns on the switch swB. Also, if no storage battery 6 is charged and discharged as a result of a malfunction of the completion and the storage battery 6 in the charge (commercial mode), to turn on the switch swA _A, to turn off the switch swC and switch swB.

In the above description, to turn on the switch swA _A in the energy storage mode and commercial mode, said turning on the switch swB in the discharge mode, as shown in FIG. 2, the necessary state of these switches is always ON No. That is, when stopping the load 2A turns off the switch swA _A in the energy storage mode and commercial mode, turning off the switch swB in the discharge mode.

  In addition, since there is a smoothing capacitor between the converter unit 8 and the inverter unit 9, there is no risk of instantaneous voltage drop due to switching of each switch if the capacity of the smoothing capacitor is sufficient.

The graph of the daily load fluctuation of the power consumption of the local electrical equipment group E stored in the control device 7 is shown in the graph of FIG. The power consumption of the local electrical equipment group E varies throughout the day as the operating states of the loads 2A to 2Z vary for various reasons. For example, in the case of midnight, the power consumption is constant because the operating states of the loads 2A to 2Z are not changed. However, the power consumption increases from the morning when the loads 2A to 2Z are activated or the operating state is changed. The increase in power consumption is not limited to that caused by manual operation, and includes, for example, that caused by automatic control such as an increase in the vane opening of the refrigerator accompanying an increase in the outdoor temperature in summer. The power consumption pattern of the on-premises electrical equipment group E as shown in the graph of FIG. 3 is measured in advance with a power meter or the like and converted into data. Note that the control device 7 may switch charge / discharge based on prediction based on the degree of fluctuation of the power consumption value of the on-site electrical equipment group E in addition to charge / discharge switching based on the daily load fluctuation pattern stored in advance. Good. The control based on the prediction based on the degree of fluctuation can be exemplified by, for example, a control for discharging from the storage battery 6 when the degree of increase in the power consumption of the on-site electrical equipment group E increases and exceeds a predetermined value.

  The control device 7 performs leveling of power consumption so that the maximum value of power consumption of the on-site electrical equipment group E becomes smaller from the correlation between the daily load fluctuation pattern and the current time shown in the graph of FIG. That is, the control device 7 charges the storage battery 6 in a region with low power consumption indicated by the symbol α1 in FIG. The switches swC to swB are controlled so as to be discharged. Specifically, the control device 7 executes the power storage mode in the time zone of the region indicated by the symbol α1, executes the discharge mode in the time zone of the region indicated by the symbol α2, and the commercial mode in the other time zones. Execute. The switching of the control mode is executed when the current time becomes a set time set based on the daily load fluctuation pattern.

  In addition, when changing from discharge mode to commercial mode, it is preferable that the control apparatus 7 switches on the occasion that the residual amount of the storage battery 6 became below predetermined value. If the transition from the discharge mode to the commercial mode is executed only at the time indicated by the daily load fluctuation pattern as shown in FIG. This is because 2A may cause a power failure.

  The control device 7 controls the switches swC to swB in this way, so that the daily load fluctuation of the power consumption of the premises electrical equipment group E is leveled with a simple equipment configuration. In FIG. As shown, the contract power can be reduced. By reducing the contract power, the cost of electricity charges can be reduced, and it can contribute to the reduction of the daily load fluctuation of the power system and the social cost of maintaining the power system. it can. For example, if daily load fluctuations are suppressed on a nationwide scale, power generation facilities necessary to secure power during peak hours during the day can be reduced, and the amount of power is provided by increasing nighttime power. As a result, the ratio of nuclear power plants that serve as base power sources can be increased, contributing to the worldwide obligation to reduce carbon dioxide emissions. The load leveling system 1 is effective when applied to a group of on-site electrical equipment having a large daily load fluctuation. For example, various peak shift systems that use ice produced by night electricity such as an ice heat storage system during the daytime. When used together, daily load fluctuations can be more thoroughly suppressed. In the above embodiment, it is assumed that the commercial power supply 4 supplies AC power. However, even if the commercial power supply 4 supplies DC power, the group of on-site electrical equipment groups is the same as in the case of AC. The daily load fluctuation of the power consumption of E can be leveled.

  The load leveling system 1 does not require a synchronization device including a phase detector or the like like a system protection device, and the device configuration is simple. Further, the storage battery 6 does not need to be a large-scale battery such as a NaS battery, and various power storage means that are widely distributed and easily available can be applied, so that facilities necessary for power storage can be simplified. The capacity of the storage battery 6 depends on the daily load fluctuation of the on-site electrical equipment group E and the load of the inverter provided with the load leveling system 1, but is large enough to be used for system stability (for example, , Several thousand kW to several tens of thousands kW class), but relatively small scale (for example, about several kW to several tens kW).

The load leveling system 1 includes, for example, a low voltage relay that detects that the commercial power supply 4 has failed, and when the low voltage relay detects a power failure of the commercial power supply 4, the controller switches the switches swC to swB. If the pattern is instantaneously switched to the discharge mode, it is possible to prevent the load 2A from being stopped due to a power failure. In this case, the system can be simplified as compared with the AC uninterruptible power supply, and it is not necessary to add devices for limiting the load so as to meet the battery capacity. The load 2A is effective when a device that is required to continue to operate even in the event of a power failure is selected. However, if equipment that operates only in an emergency is applied, load leveling, which is the original purpose, cannot be realized, so care must be taken in selecting equipment that operates in both normal and emergency situations.

  In addition, the power failure of the commercial power supply 4 may be detected not only by what is detected by a low voltage relay etc. but by the signal etc. which are sent from the outside, for example. Further, the control device 7 may switch the switches swC to swB based on not only the power failure of the commercial power supply 4 but also other various external signals. If the equipment that is required to operate in an emergency can be operated by the load leveling system 1, the emergency power generation equipment installed in the premises electrical equipment group E due to legal obligations or other circumstances The power generation capacity can be reduced.

  Further, the load leveling system 1 does not necessarily need to level the power consumption so that the maximum value of the power consumption of the local electrical equipment group E is low. For example, as shown in the graph of FIG. 4, when there is a request to reduce power consumption in the evening time zone, the storage battery 6 charged in the region indicated by the symbol β1 is stored in the region indicated by the symbol β2 ( For example, the switches swC to swB may be controlled so as to be discharged after 16:00. Further, the storage battery 6 in which electricity remains after elapse of the region indicated by the symbol α2 in FIG. 3 may be discharged again in the region indicated by the symbol β2 in FIG.

  In addition, the load leveling system 1 performs load leveling based on the daily load fluctuation pattern of the power consumption of the local electrical equipment group E stored in the control device 7. The pattern of the daily load fluctuation of the power may be acquired and created by the control device 7. In this case, the control device 7 of the load leveling system 1 uses, for example, a premises electric facility based on a wattmeter 13 provided between the commercial power supply 4 and the premises electric facility group E, as indicated by a symbol * in FIG. The daily load fluctuation of the power consumption of group E is measured.

  Then, the control device 7 keeps the switches swC to swB in the commercial mode, and from the daily load fluctuation data of the local electrical equipment group E measured by the wattmeter 13, the campus as shown in FIG. 3 and FIG. The daily load fluctuation pattern of the power consumption of the electrical equipment group E can be obtained. The control device 7 controls the switches swC to swB according to the pattern of FIG. 2 based on the daily load fluctuation data of the premises electrical equipment group E obtained by measuring with the wattmeter 13, and the load leveling as described above is performed. To do. In this case, the timing at which the control pattern is switched is not the set time defined based on the daily load fluctuation data as described above, but the capacity of the storage battery 6, the on-site electrical equipment group E, or the power consumption of the load 2A, for example. Various calculation processes may be performed from the integrated power amount, and the control pattern switching timing may be determined so that the maximum value of the power consumption of the on-premises electrical equipment group E is minimized.

  In the above embodiment, one load leveling system 1 is provided in the on-site electrical equipment group E. However, the load leveling system 1 is provided on each of a plurality of inverters provided in the same on-site electrical equipment group. May be. When the load leveling system 1 is provided in combination with two inverters provided in the same group of electrical equipment on the same premises, the number of storage batteries 6 is also two, so the capacity that can be stored (discharged) in the entire system increases, and the graph of FIG. As shown in FIG. 4, the daily load fluctuation can be further suppressed as compared with the case where there is only one load leveling system 1.

  In the above embodiment, one load leveling system 1 is provided for one inverter 5A, but one load leveling system 1 may be provided for a plurality of inverters. A modification in this case is shown in FIG.

In this modification, an inverter 5A is installed in the load 2A, and the inverter 5 is installed in the load 2B.
Assume that B is installed. When there are two inverters in the premises electrical equipment group E as described above, the control device 7 of the load leveling system 1 switches the switch swA _A and the first power supply circuit 11B connected to the inverter 5B from the commercial power supply 4. SwA _B is controlled. The switch swA _A and the switch swA _B may be mechanically coupled and opened / closed simultaneously, or may be electrically connected to the same control line and opened / closed simultaneously.

  When the load leveling system 1 is provided with two inverters, the discharge speed of the storage battery 6 in the discharge mode is faster than when the load leveling system 1 is provided with one inverter. . However, since the power flowing from the commercial power source 4 to the local electrical equipment group E is reduced during the discharge mode, the peak value of power consumption can be further reduced. Therefore, when the daily load fluctuation pattern of the power consumption of the premises electrical equipment group E draws a mountain shape in which the peak of power during the day is relatively abrupt, in other words, the power consumption is more than the duration of the discharge mode. When priority is given to keeping the peak value low, it is effective to place the load leveling system 1 on a plurality of inverters instead of one inverter.

  Strictly speaking, such an effect does not depend on the number of inverters provided in the load leveling system 1, but depends on the power consumption of all inverters provided in the load leveling system 1. . In any case, in proportion to the magnitude of the electrical load of the inverter provided in the load leveling system 1, the peak of the electric power of the local electrical equipment group E can be kept low in the discharge mode. Therefore, for example, the control device 7 is provided with the switches swC and swB for each inverter so that the discharge mode and the commercial mode can be selected for each inverter. From a relationship such as an increase rate of power consumption, a discharge mode or a commercial mode may be selected for each inverter so that the peak value of electric power in the local electrical equipment group E can be controlled.

E ... Electrical equipment group 1 ... Load leveling system 2A-Z ... Load 3 ... Load group 4 ... Commercial power supply 5A ... Inverter 6 ... Storage battery 7 ... Control Device 8 ... Converter unit 9 ... Inverter unit 10 ... Charging circuit 11A, B ... First feeding circuit 12 ... Second feeding circuit 13 ... Wattmeter 14 ... Rectifier

Claims (5)

A load leveling system for leveling the power consumption of a specific group of electrical equipment including the predetermined electrical equipment in addition to an inverter device that controls the operating state of the predetermined electrical equipment with supplied AC power,
Power storage means charged by a charging circuit connected from a power source that supplies power to the specific electrical equipment group;
When the power consumption of the specific electrical equipment group is larger than the power consumption of the specific electrical equipment group at the time of charging the power storage means, the first power supply circuit connected from the power source to the inverter device is opened and the power storage Control means for closing the second power supply circuit connected from the means to the inverter device and supplying electricity from the power storage means to the inverter device,
Load leveling system. The control means closes the charging circuit and charges the power storage means at night time when the power consumption of the specific electrical equipment group is smaller than the daytime, and the power consumption of the specific electrical equipment group Opening the first power feeding circuit and closing the second power feeding circuit to feed the electricity of the power storage means to the inverter device during a daytime period greater than the time of charging the power storage means,
The load leveling system according to claim 1. The control means opens and closes the first power supply circuit and the second power supply circuit based on a daily load fluctuation pattern of power consumption of the specific electrical equipment group.
The load leveling system according to claim 1 or 2. The control means obtains the daily load fluctuation pattern from a power meter that measures power consumption of the specific electrical equipment group.
The load leveling system according to claim 3. The power source is alternating current;
The inverter device is supplied with power from the power source converted from alternating current to direct current by a converter device and smoothed by a smoothing capacitor,
The power storage means is charged by the charging circuit provided with a rectifier that converts alternating current to direct current,
The second power supply circuit connects the storage device and a circuit connecting the converter device and the inverter device,
The load leveling system according to any one of claims 1 to 4.

Images