JP5268458B2 - Supply and demand control equipment for small power systems - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a supply and demand controller in a small-scale electric power system which can avoid the charging end or discharging end of an electric storage device. <P>SOLUTION: The supply and demand controller in a small-scale electric power system includes a variable output power generator 14, an electric storage device 13, a load 15 to which electric power is supplied from the power generator and the electric storage device, and a supply and demand controller S/D which controls the power generator and the electric storage device in such a manner that supply and demand of the power generator and the electric storage device are balanced, wherein the supply and demand controller includes a controller which controls the electric storage device in such a manner that the difference between the planned charge/discharge value and the output power thereof is decreased, and corrects the output command value of the power generator according to a control amount which is output from the controller. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a supply and demand control device for a small-scale power system, and more particularly, to a device that performs control so as to prevent the end of charging and discharging of a power storage device.

  In general, when a small-scale power system is connected to a commercial system, fluctuations in the power flow of the interconnection line connecting the small-scale power system and the commercial system are kept small, and power from the commercial system is reduced within a certain period of time. It is necessary to satisfy the same amount at the same time.

  In this interconnection, in accordance with the contract with the electric power company, the flow of the interconnection line is controlled so as to be within the contract. In this case, if you deviate from the contract, a fine may be required. In addition, when a small-scale power system is separated from a commercial system for independent operation, the frequency within the small-scale power system will fluctuate if the power supply and demand balance is not properly balanced within the small-scale power system. It becomes impossible to supply power stably in the system.

  In order to prevent such a problem, a method of balancing supply and demand as much as possible with an output variable generator using a rotating machine and balancing the supply and demand with a power storage device with a fast response speed is used for the remaining unbalance.

  In this method, in order to ensure sufficient control performance, it is necessary to increase the capacity of the power storage device. However, there is a problem that the price of the power storage device is high and the capacity is increased when the capacity is increased.

  Further, when trying to suppress the capacity to be small, there is a problem that charging or discharging tends to occur, and the necessary control performance may not be obtained when necessary.

In order to prevent the end of charging or discharging, the command value of the power output to the system is changed stepwise or linearly according to the amount of power stored in the power storage device (see, for example, Patent Document 1).
JP 2001-327080 JP

  If the command value of power output to the grid is changed stepwise or linearly according to the amount of electricity stored in the electricity storage device described above, the amount of electricity stored will be reduced if the output of the electricity storage device deviates from the operation plan in order to satisfy the supply-demand balance. A state occurs where the number is too much or too little than planned, and the output from the power storage device cannot be obtained as much as necessary.

  The present invention has been made in consideration of the above-described points, and an object of the present invention is to obtain a supply and demand control device for a small-scale power system that can avoid the end of charging and discharging of a power storage device.

In order to achieve the above object, in the present invention,
A generator with variable output, a power storage device, a load fed from the power generator and the power storage device, and a power supply plan including long-cycle control and short-cycle control. In a supply and demand control device for a small-scale power system comprising a control device for controlling the power generator and the power storage device so as to balance,
The controller is
A controller that performs control so that the difference between the charge / discharge planned value and the output power in the power storage device is reduced,
A supply and demand control device for a small-scale power system, wherein the output command value of the generator is corrected by a control amount output from the controller,
Is to provide.

  Since the present invention is configured as described above, it can be operated in a state closer to the charge / discharge planned value of the power storage device, and it becomes easy to prevent the power storage device from being charged or discharged.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Example 1
A first embodiment will be described with reference to FIGS. FIG. 6 is a block diagram of supply and demand control of a general small-scale power system to which the present invention is applied.

  As shown in FIG. 6, a general small-scale power system includes one or more power storage devices 13 connected to the power system bus 12, one or more output variable generators 14, and one or more power generators 14. In this configuration, the load 15 is provided.

  This small-scale power system is operated by the long cycle control 10 and the short cycle control 11 based on the power generation plan 9 in the supply and demand control device S / D indicated by the broken line. That is, first, in the power generation plan 9, a relatively long time, for example, from a load prediction in a small-scale power system or prediction of a power generation amount of a generator that cannot control a power generation amount such as wind power generation using natural energy, for example, An operation plan for the variable output power generator 14 and the power storage device 13 is created every 30 minutes to 1 hour.

  Then, based on this operation plan, the long-term control 10 generates a power generation amount of the variable output power generator 14 in units of several minutes and the output of the power storage device 13 so that the actual demand and the power generation amount in a few minutes are balanced. Competence is calculated.

  Further, based on the output amount, the short-term control 11, for example, the power generation amount of the variable output power generator 14 and the control amount of the power storage device 13 are calculated in units of several seconds so that the actual demand for several seconds and the power generation amount are balanced. To do. Then, the control amount is given as a command value to the output variable generator 14 and the power storage device 13, and the output variable generator 14 and the power storage device 13 are operated according to the command value. Is realized.

  The operation plan created in the power generation plan 9 is optimized for each index such as operation cost, and is generally created so that the power storage device 13 does not end at the end of charging or discharging.

  FIG. 1 shows a first embodiment of the present invention. FIG. 1 is obtained by adding the following functions to the general supply and demand control apparatus shown in FIG.

  First, the output power of the power storage device 13 is detected using the voltage detection means 1 that detects the voltage at the connection point of the power storage device 13, the current detection means 2 that detects the current flowing into or out of the power storage device 13, and the multiplier 3. Is calculated.

  Next, a difference obtained by subtracting the charge / discharge planned value from the output power of the power storage device 13 calculated by the multiplier 3 is calculated by the adder 4 and given to the adder 5. Then, in the adder 5, the output from the adder 4 is added by m power storage devices, the control amount is calculated by the controller 6 so that the difference becomes 0, and the calculated control amount is allocated to the distributor. Give to 7. As a result, the amount to be distributed to each of the variable output power generators 14, that is, the control amount that the variable output power generator 14 should output separately is obtained.

  Then, the control amount calculated by the distributor 7 is added by the adder 8 to the output command value to each generator created by the short cycle control 11 in the supply and demand controller S / D, and this is added to the output variable power generation. Is given to the machine 14 as a command value, and the output variable generator 14 is operated according to the command value.

  In the present invention, the power generation plan 9, the long cycle control 10, and the short cycle control 11, which are the center of the simultaneous equal amount control performed by the supply and demand control device S / D, do not necessarily need to be divided into three stages. The charging / discharging plan value of the power storage device 13 to be performed, the output command to the output variable generator 14 and the output command to the power storage device 13 calculated by the short cycle control 11 may be obtained.

  Incidentally, FIG. 1 is a block diagram when the discharge is positive, and when the discharge is negative, the sign of the adder in FIG. 1 is modified to an appropriate one.

  Details of the first embodiment will be described. Although it is a state quantity used for addition by the adder 4, the output power calculated by the multiplier 3 is W (power value). Therefore, if the charge / discharge plan value created in the power generation plan 9 is W, it remains as it is. What is necessary is just to add, but when it is Wh (electric energy value), it converts into W at the time of using for control, and uses.

  FIG. 2 is a control characteristic diagram illustrating the supply and demand control method used in the present invention, and is a method for making the unit cross sections 101, 102, 103, and 104 shown in FIG. 2 (a) constant and the time passage shown in FIG. 2 (b). There is a method that changes continuously as a result. If the charge / discharge plan values used in the processes after the long-cycle control 10 are used as shown in FIG. 2A, the method of FIG. 2A is used. If the method shown in FIG. Apply method 2 (b).

  The output command to the variable output power generator 14 and the output command to the power storage device 13 calculated by the short cycle control 11 are W. In the controller 6, various controls such as proportional-integral control can be used as long as the input value can be controlled to be zero.

  If integration control is turned on, the difference from the planned charge / discharge value is integrated. Therefore, if the accumulated output amount of the power storage device 13 is smaller than the accumulated charge / discharge planned value, the integral control always shows a negative value. Is continuously output, and when the total output amount of the power storage device 13 is larger than the total charge / discharge planned value, a positive value is always output from the integral control.

  That is, since control is always performed such that the cumulative charge / discharge value is equal to the cumulative output amount of the power storage device 13, operation close to the charge / discharge value can be expected.

  In the first embodiment configured as described above, when the output of the adder 5 is positive, it indicates that the power storage device 13 is discharged more than the planned charge / discharge value. The output variable generator 14 generates more power than usual by adding to the output command value.

  As a result, the supply power in the small-scale power system becomes excessive. However, when the small-scale power system is connected to the commercial system, the power generation plan 9 in the supply / demand control device S / D, the long cycle control 10, the short When the interconnected power flow constant control of the cycle control 11 works and the small-scale power system is operating independently, the constant frequency control of the power generation plan 9, the long cycle control 10, and the short cycle control 11 works.

  For this reason, as a result, the amount of power generated by the variable output power generator 14 is subtracted from the charge / discharge amount of the power storage device 13, and the balance between supply and demand in the small-scale power system is maintained. 13 can be operated in a state closer to the charge / discharge planned value.

  Conversely, when the output of the adder 5 is negative, it indicates that the power storage device 13 is discharged less than the planned charge / discharge value, so that this amount is added to the output command value to the output variable generator 14. Therefore, the variable output power generator 14 generates power less than usual.

  As a result, the supply power in the small-scale power system is insufficient. In this case, if the small-scale power system is connected to the commercial system, the constant power flow control of the power generation plan 9, the long-cycle control 10, and the short-cycle control 11 works, and the small-scale power system operates independently. If so, the constant frequency control of the power generation plan 9, the long cycle control 10, and the short cycle control 11 works.

  As a result, a small amount of power generated by the variable output power generator 14 is added to the charge / discharge amount of the power storage device 13, and the supply and demand balance in the small-scale power system is maintained, and at the same time It becomes possible to operate the apparatus 13 in a state closer to the charge / discharge planned value.

  According to the first embodiment, the power storage device 13 can be operated in a state closer to the planned charge / discharge value created so as not to reach the end of charging or discharging, so that it is easy to prevent the end of charging or discharging. Become. Accordingly, it is possible to prevent the charge / discharge necessary for the same amount control from being performed. Further, the operation margin of the power storage device 13 can be reduced, the power storage device can be used more effectively, and the required capacity of the power storage device 13 can be reduced.

(Example 2)
A second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing a second embodiment of the present invention, which is a partial extract of the block diagram of FIG. 1 described in the first embodiment. In addition, the same code | symbol is attached | subjected to the structure same as Example 1, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 3, the function of changing the control constant based on the charging / discharging information of the power storage device 13 is added to the block diagram (FIG. 1) described in the first embodiment. In FIG. 3, the switch 22 b is opened when the switch 22 a is closed, and the switch 22 a is opened when the switch 22 b is closed. When discharging, the switch 22a is closed to multiply the gain "1" by the gain 21a, and when charging, the switch 22b is closed to multiply the gain 21b by the gain "1.02".

  Note that the gain constant in FIG. 3 is an example, and it is not always necessary to use this value. Further, the control element after the gain is configured only by the integrator 23, but is not limited to the integrator, and the integrator 23 is replaced with the gain, the gain is placed in parallel with the integrator 23, or the like. Other controls may be put in parallel in the controller 6 and applied to various combinations of controls.

  The effect of this method will be described. The power storage device 13 having a direct output is converted from direct current to alternating current and connected to the system bus 12. However, the converter generally has a large loss when converted from alternating current to direct current. Therefore, when integration control is put into the controller 6 of the first embodiment, if charging and discharging are repeated, a difference occurs in the integrated value in the integrator 23 due to the influence of loss.

  Therefore, as shown in FIG. 3, it is possible to operate in a state closer to the charge / discharge planned value by correcting the influence of the loss as a control constant that increases the accumulated amount at the time of discharging with a large loss. It becomes easy to prevent the end of charging or discharging of the device. Accordingly, it is possible to prevent the charge / discharge necessary for the same amount control from being performed.

  In addition, since the operation margin of the power storage device 13 can be reduced, the power storage device can be used more effectively and the required capacity of the power storage device 13 can be reduced.

(Example 3)
A third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram showing a third embodiment of the present invention, which is a partial extract of the block diagram of FIG. 1 described in the first embodiment. In addition, the same code | symbol is attached | subjected to the structure same as Example 1, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 4, the function of adding the control amount based on the output value of the integrator 31 through the output of the adder 5 is added to the block diagram of FIG. 1 described in the first embodiment. . When it deviates significantly from the charge / discharge plan value, the absolute value of the output of the integrator 31 becomes large. Depending on the value, the switches 33a and 33b are closed so as to be close to the planned charge / discharge value, and the constants 32a and 32b are added to the control amounts output from the controller 6 by the adder 34, respectively.

  In FIG. 4, only two switches and constants are shown. However, the number is not limited to two, and one or a plurality of constants may be used. Moreover, the addition method may add all at once, or may add stepwise according to the output value from the integrator 31.

  By using the method of the present invention, it becomes easy to return to the charge / discharge planned value from the state deviated from the charge / discharge planned value, so that it is possible to prevent the charge / discharge necessary for the same amount control from being performed.

  In addition, since the operation margin of the power storage device 13 can be reduced, the power storage device can be used more effectively and the required capacity of the power storage device 13 can be reduced.

Example 4
A fourth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a block diagram showing a fourth embodiment of the present invention, and is a partial extract of the block diagram of FIG. 1 described in the first embodiment. In addition, the same code | symbol is attached | subjected to the structure same as Example 1, and the overlapping description is abbreviate | omitted.

  In FIG. 5, the function of switching the output from the controller 6 and the constant according to the information on the storage amount is added to the block diagram of FIG. 1 described in the first embodiment. According to the storage amount information, when the end of charging is approached, the switch 42a is closed and simultaneously the switches 42b and 42c are opened.

  As a result, the output of the constant 41a continues to be output as a controlled variable, so that a constant value is always output when approaching the end of charging, and discharge is performed stably when the end of charging is about to occur. become.

  Conversely, when the end of discharge is approached, the switch 42b is closed and the switches 42a and 42c are opened simultaneously. As a result, the output of the constant 41b continues to be output as a controlled variable, so that a constant value is always output when approaching the end of discharge, and charging is performed stably when the end of discharge is likely to occur. become.

  Note that it is a timing when the switches 42a and 42b are closed and then opened again, and the switch 42c is closed. However, based on the storage amount information, the switch 42a and 42b may be opened when the storage amount exceeds a certain value. Then, it may be opened after a certain time from closing.

  Further, in FIG. 5, there is only one switch and a constant at the end of discharging and at the end of charging, respectively, but a plurality of constants may be used and the constant may be changed step by step based on the charge amount information. The present invention is not limited to the above-described embodiment, and can be applied as long as it is a method capable of performing equivalent control.

  According to the present invention, since the constant value continues to be output even when the end of charging or discharging of the power storage device is reached, the end of charging or discharging is eliminated earlier than a general supply and demand control device. It is possible to shorten the state where the same amount control cannot be performed sufficiently.

The block diagram explaining the structure of Example 1 of this invention. FIG. 6 is a control characteristic diagram for explaining the operation of the first embodiment of the present invention. The block diagram explaining the structure of Example 2 of this invention. The block diagram explaining the structure of Example 3 of this invention. The block diagram explaining the structure of Example 4 of this invention. A block diagram of a general small-scale power system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Voltage detector, 2 ... Current detector, 3 ... Multiplier, 4 ... Adder, 5 ... Adder,
6 ... Controller, 7 ... Distributor, 8 ... Adder, 9 ... Power generation plan creation unit, 10 ... Long cycle control unit,
DESCRIPTION OF SYMBOLS 11 ... Short cycle control part, 12 ... Electric power system bus line, 13 ... Power storage device, 14 ... Output variable generator,
15 ... load, 21a, 21b ... switch, 22a, 22b ... gain, 23 ... integrator,
31 ... integrator, 32a, 32b ... constant, 33a, 33b ... switch, 34 ... adder,
41a, 41b ... constant, 42a, 42b, 41c ... switch, S / D ... supply-demand control device.

Claims (4)

A generator with variable output, a power storage device, a load fed from the power generator and the power storage device, and a power supply plan including long-cycle control and short-cycle control. In a supply and demand control device for a small-scale power system comprising a control device for controlling the power generator and the power storage device so as to balance,
The controller is
A controller that performs control so that the difference between the charge / discharge planned value and the output power in the power storage device is reduced,
A supply and demand control device for a small-scale power system, wherein an output command value of the generator is corrected by a control amount output from the controller. The supply and demand control device for a small-scale power system according to claim 1,
The controller is capable of changing a control constant,
The supply and demand control device for a small-scale power system, wherein the control constant is changed according to operating state information relating to charging or discharging of the power storage device. The supply and demand control device for a small-scale power system according to claim 1,
A supply and demand control device for a small-scale power system, wherein a control amount output from the controller is corrected based on an integrated value of a difference between a charge / discharge planned value of the power storage device and output power. The supply and demand control device for a small-scale power system according to claim 1,
The supply and demand control device for a small-scale power system, wherein the output command value of the generator is corrected by a control amount determined by the storage amount information of the power storage device.

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