JP2015077022A - Charge/discharge control device and charge/discharge control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress fluctuation in a system frequency in a short time by starting suppression of disturbance in a power system immediately after occurrence of the disturbance.SOLUTION: A bidirectional power conversion device 30 controls charge/discharge of a secondary battery 22 connected to a power system 14. The bidirectional power conversion device 30 calculates a disturbance suppression operation instruction value, which is a charge/discharge instruction value with regard to the secondary battery 22 to suppress system disturbance, on the basis of a detection value of a system frequency; and performs switching from a normal operation instruction value, which is a charge/discharge instruction value in the case where system disturbance does not occur, to the disturbance suppression operation instruction value, when a disturbance occurrence condition showing occurrence of the system disturbance is satisfied.

Description

  The present invention relates to a charge / discharge control device and a charge / discharge control method for a secondary battery.

  In order to realize a stable supply of power, the power system, for example, reduction or disconnection of a large power plant that supplies power to the power system, stop of power consumption of large load facilities connected to the power system, etc. Even if the system disturbance caused by the above occurs, it is required to keep the system frequency constant.

  Patent Documents 1 and 2 disclose a technique for charging and discharging a secondary battery connected to the power system in order to stabilize the power system in which the system disturbance has occurred.

JP 2012-130146 A JP 2001-292531 A

FIG. 7 shows a fluctuation state of the system frequency in the system disturbance.
As shown in FIG. 7, a primary frequency response in which the system frequency greatly fluctuates between several tens of seconds (for example, 10 to 30 seconds) after the occurrence of the system disturbance occurs. After that, stabilization of the system frequency was performed in the secondary frequency response of several minutes to about 10 minutes in the quasi-equilibrium state in which the fluctuation of the system frequency becomes small.
Several seconds immediately after the occurrence of the fluctuation of the system frequency in the primary frequency response is the intrinsic response. In Inertial Response, system disturbance occurs and the system frequency starts to change (rise or fall) abruptly. It is expected that the suppression of the fluctuation of the system frequency in the intrinsic response will improve the frequency fluctuation in the primary frequency response.

Here, in the power stabilization control through the arithmetic processing in the conventional PLC (Programmable logic controller), the charge / discharge command value for the secondary battery is updated at a cycle of about 1 second to about 2 seconds.
However, in the update cycle as described above by the PLC, it is difficult for the charge / discharge of the secondary battery to sufficiently contribute to suppression of fluctuation with respect to the initial response immediately after the occurrence of the system disturbance. For this reason, the charging / discharging control command is delayed to cope with the occurrence of system disturbances, in which the secondary battery is discharged when the system frequency is lowered and charged when the system frequency is increased, and fluctuations in the system frequency are suppressed in a short time. There was a limit.

  The present invention has been made in view of such circumstances, and is a charging / discharging control device and a charging / discharging device capable of starting suppression of disturbance immediately after the occurrence of disturbance in the power system and suppressing fluctuation in system frequency in a short time. An object is to provide a discharge control method.

  In order to solve the above problems, the charge / discharge control device and the charge / discharge control method of the present invention employ the following means.

  A charge / discharge control apparatus according to a first aspect of the present invention is a charge / discharge control apparatus that controls charge / discharge of a secondary battery connected to a power system via power conversion means for converting DC power and AC power. Normal operation calculation means for calculating a normal operation command value, which is a charge / discharge command value for the secondary battery for stabilizing the power supplied to the power system, and the disturbance for suppressing disturbance of the power system. Disturbance suppression operation calculation means for calculating a disturbance suppression operation command value, which is a charge / discharge command value for the secondary battery, based on a detected value of the frequency of the power system, and a disturbance generation condition indicating occurrence of the disturbance are satisfied A switching means for switching a charge / discharge command value for the secondary battery from the normal operation command value to the disturbance suppression operation command value.

The charge / discharge control device according to this configuration controls charge / discharge of a secondary battery connected to an electric power system that supplies power to a load. Further, during normal operation, the power supplied to the power system is stabilized.
Therefore, a normal operation command value, which is a charge / discharge command value for the secondary battery for stabilizing the power supplied to the power system, is calculated by the normal operation calculation means.

Disturbances may occur in the power system. When a disturbance occurs, the disturbance is suppressed by discharging or charging the secondary battery.
Therefore, a disturbance suppression operation command value, which is a charge / discharge command value for the secondary battery for suppressing the disturbance, is calculated by the disturbance suppression operation calculation means based on the detected value of the frequency of the power system. The disturbance suppression operation calculating means constantly calculates a disturbance suppression operation command value regardless of whether or not a disturbance has occurred.

  And when the disturbance generation conditions which show generation | occurrence | production of the disturbance of an electric power grid | system are satisfy | filled, the charge / discharge command value with respect to a secondary battery is switched from a normal operation command value to a disturbance suppression operation command value by the switching means. Further, the normal operation command value is a charge / discharge command value for the secondary battery when there is no disturbance in the power system.

As described above, this configuration constantly calculates the disturbance suppression operation command value for the secondary battery regardless of whether or not the disturbance occurs. The operation command value can be switched to the disturbance suppression operation command value.
By switching to the disturbance suppression operation command value along with the occurrence of the disturbance, the secondary battery can sufficiently contribute to the suppression of the fluctuation with respect to the initial response immediately after the occurrence of the disturbance.

  Therefore, this configuration can start the suppression of the disturbance immediately after the occurrence of the disturbance of the power system, and can suppress the fluctuation of the system frequency in a short time.

  In the first aspect, the disturbance suppression operation calculation means calculates the disturbance suppression operation command value based on the difference between the detected value of the frequency of the power system and the rated frequency of the power system and the rated capacity of the secondary battery. It is preferable to calculate.

  According to this configuration, since the method for calculating the disturbance suppression operation command value is simple, the disturbance suppression operation command value can be updated at a fast cycle, and it is possible to cope with the Inertial Response due to charging / discharging of the secondary battery.

  In the first aspect, it is preferable that the disturbance generation condition is outside a predetermined range in which the frequency of the electric power system indicates no occurrence of disturbance, and a fluctuation rate of the frequency of the electric power system is not less than a first predetermined value.

  The frequency of the power system varies to some extent. For this reason, even if the frequency of the power system is outside a predetermined range indicating the absence of disturbance, the frequency may return to the range immediately. In such a case, so-called hunting in which switching between the disturbance suppression operation command value and the normal operation command value is repeated may occur.

  Therefore, this configuration is switched to the disturbance suppression operation command value when the frequency of the power system is out of the predetermined range indicating the non-occurrence of disturbance and the fluctuation rate of the frequency of the power system is greater than or equal to the first predetermined value. That is, even if the frequency of the power system is outside the predetermined range, if the fluctuation rate of the frequency of the power system is less than the first predetermined value, the frequency immediately returns to the predetermined range, so that no disturbance is generated. .

  Therefore, this configuration can prevent repeated switching between the disturbance suppression operation command value and the normal operation command value.

  In the first aspect, when the switching means has a frequency variation rate of the power system that is equal to or less than a second predetermined value that is smaller than the first predetermined value, the charge / discharge command value for the secondary battery is It is preferable to switch from the disturbance suppression operation command value to the normal operation command value.

  According to this configuration, it is possible to prevent repeated switching between the disturbance suppression operation command value and the normal operation command value.

  In the first aspect, when the switching unit is in a discharged state and not more than a predetermined charging rate, or when the secondary battery is in a charging state and becomes not less than a predetermined charging rate, It is preferable to switch the charge / discharge command value for the secondary battery from the disturbance suppression operation command value to the normal operation command value.

  Even if the charging rate becomes too high or too low, the secondary battery promotes deterioration. For this reason, this structure can suppress deterioration of a secondary battery.

  In the first aspect, when the switching unit continues for a predetermined time or longer that the frequency of the power system is within a predetermined range indicating suppression of the disturbance, the charge / discharge command value for the secondary battery is set to the disturbance. It is preferable to switch from the suppression operation command value to the normal operation command value.

  Disturbances in the power system are suppressed while repeating frequency fluctuations. For this reason, even if the frequency of the power system falls within a predetermined range indicating disturbance suppression, the frequency may be immediately outside the range. In such a case, hunting in which switching between the disturbance suppression operation command value and the normal operation command value is repeated may occur.

  Therefore, this configuration switches the disturbance suppression operation command value to the normal operation command value when the frequency of the power system remains within the predetermined range for a predetermined time or longer. That is, even if the frequency of the power system falls within the predetermined range, if the state does not continue, the disturbance is not stabilized.

  Therefore, this configuration can prevent repeated switching between the disturbance suppression operation command value and the normal operation command value.

  The charge / discharge control method according to the second aspect of the present invention is a charge / discharge control method for controlling charge / discharge of a secondary battery connected to a power system through power conversion means for converting DC power and AC power. A first step of calculating a normal power command value that is a charge / discharge command value for the secondary battery for stabilizing the power supplied to the power system, and the second step for suppressing disturbance of the power system. A second step of calculating a disturbance suppression operation command value, which is a charge / discharge command value for a secondary battery, based on a detected value of the frequency of the power system, and when a disturbance generation condition indicating the occurrence of the disturbance is satisfied, And a third step of switching the charge / discharge command value for the secondary battery from the normal operation command value to the disturbance suppression operation command value.

  According to the present invention, there is an excellent effect that disturbance suppression is started immediately after the occurrence of disturbance in the power system, and fluctuations in the system frequency can be suppressed in a short time.

It is a lineblock diagram of an electric power system concerning an embodiment of the present invention. It is a block diagram which shows charge / discharge control of the secondary battery which concerns on embodiment of this invention. It is a flowchart which shows the flow of the driving | operation switching process which concerns on embodiment of this invention. It is a figure required for description of the disturbance generating condition which concerns on embodiment of this invention. It is a figure required for description of the disturbance suppression conditions which concern on embodiment of this invention. It is a block diagram of the electric power system which concerns on other embodiment of this invention. It is a figure which shows the fluctuation state of the system frequency in a system disturbance.

  EMBODIMENT OF THE INVENTION Below, one Embodiment of the charging / discharging control apparatus and charging / discharging control method which concern on this invention is described with reference to drawings.

  FIG. 1 is a configuration diagram of a power system 10 according to the present embodiment.

The power system 10 includes a local system 12 and a power system 14.
The local system 12 includes a generator 20, a secondary battery 22, and a charge / discharge control device 11 that performs charge / discharge control of the secondary battery 22. The charge / discharge control device 11 includes a bidirectional power conversion device 30 that converts DC power and AC power and a secondary battery controller 32. The on-premises system 12 supplies power from the secondary battery 22 via the generator 20 and the bidirectional power converter 30 to the power system 14 via the transformer 24.

  The generator 20 is connected to the power transmission line of the local system 12 via the transformer 24. The generator 20 may be a generator using natural energy such as a wind power generator or a solar power generator, or may be a generator not using natural energy such as a steam turbine or a gas turbine. When the generator 20 is a wind power generator, for example, the local system 12 corresponds to a wind farm.

  The power system 14 may also be provided with the generator 20, and a plurality of local systems 12 may be connected to the power system 14.

  The secondary battery 22 is connected to the power transmission line of the premises system 12 via the bidirectional power converter 30 and the transformer 24.

  The secondary battery 22 performs charge / discharge in order to stabilize the power supplied to the power system 14. In particular, when the generator 20 is a generator using natural energy, the generated power tends to become unstable due to changes in weather. Therefore, when the generated power of the generator 20 is small, the secondary battery 22 is discharged, and when the generated power of the generator 20 is large, the secondary battery 22 is charged to supply to the power system 14. Power is stabilized.

Further, the secondary battery 22 performs charge / discharge for the purpose of suppressing the system disturbance when a disturbance (hereinafter referred to as “system disturbance”) occurs in the power system 14 or the on-site system 12.
When a system disturbance occurs, the system frequency increases or decreases. When the system frequency increases, the secondary battery 22 contributes to suppression of system disturbance by charging. On the other hand, when the system frequency falls, the secondary battery 22 contributes to suppression of system disturbance by discharging.
The system disturbance is detected by the fluctuation of the frequency of the local system 12 connected to the power system 14 (hereinafter referred to as “system frequency”). A system frequency is calculated | required by converting the voltage signal of a power transmission line.

  In the case of normal operation in which no system disturbance has occurred, the secondary battery 22 according to the present embodiment is a charge / discharge command value (active power command value) calculated by the secondary battery controller 32 using, for example, the system frequency as input information. The charge / discharge is controlled by the normal operation command value. Thereby, the electric power supplied to the electric power grid | system 14 at the time of normal driving | operation is stabilized.

The secondary battery controller 32 receives a detection value (hereinafter referred to as “detected SOC”) of the charging rate (SOC) of the secondary battery 22 from the secondary battery 22.
Then, the secondary battery controller 32 generates a charge / discharge command value for the secondary battery 22 in a normal operation in which no system disturbance has occurred, and outputs the charge / discharge command value to the bidirectional power converter 30.

  The bidirectional power conversion device 30 includes a power conversion controller 30A and a power conversion unit 30B.

  The power conversion controller 30 </ b> A controls the power conversion unit 30 </ b> B based on the input charge / discharge command value, and charges / discharges the power corresponding to the charge / discharge command value from the secondary battery 22.

  The power conversion unit 30B converts the DC power discharged from the secondary battery 22 into AC power and outputs the AC power to the local system 12, and converts the AC power from the local system 12 into DC power and charges the secondary battery 22 Let

The bidirectional power conversion unit 30B includes a command value switching unit 30C.
The command value switching unit 30C switches between a normal operation command value and a disturbance suppression operation command value, the details of which will be described later, and inputs them to the power conversion controller 30A.
In the following description, the operation mode of the secondary battery 22 using the normal operation command value is referred to as a normal operation mode, and the operation mode of the secondary battery 22 using the disturbance suppression operation command value is referred to as a disturbance suppression operation mode.

  The secondary battery controller 32, the power conversion controller 30A, and the command value switching unit 30C are configured by, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a computer-readable recording medium, and the like. . A series of processes for realizing various functions is recorded on a recording medium or the like in the form of a program as an example, and the CPU reads the program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized.

FIG. 2 is a block diagram showing charge / discharge control of the secondary battery 22.
The normal operation calculation unit 40, the disturbance suppression operation calculation unit 42, the command value switching unit 30C, the power conversion controller 30A, and the power conversion unit 30B are mainly involved in the charge / discharge control of the secondary battery 22.

The normal operation calculation unit 40 calculates the charge / discharge amount of the secondary battery 22 according to the power generation output value indicating the power generation amount of the generator 20 as the normal operation command value. The normal operation calculation unit 40 constantly calculates the normal operation command value regardless of whether or not the system disturbance has occurred.
The power generation output value is output from the power generator controller 44 that controls the power generator 20 to the normal operation calculation unit 40.

  The normal operation calculation unit 40 includes a secondary battery limiter 50, a smoothing filter 52, a power conversion output limiter 54, and an SOC correction control unit 56.

  The secondary battery limiter 50 receives the power generation output value via the adder 58, limits the input value with the upper and lower limit values regarding the capacity of the secondary battery 22, and outputs the limit value to the smoothing filter 52.

  The smoothing filter 52 smoothes the output from the secondary battery limiter 50.

  The value smoothed by the smoothing filter 52 is subtracted by the power generation output value by the subtracting unit 60.

  The power conversion output limiter 54 limits the value output from the subtraction unit 60 with the upper and lower limit values of power that can be converted by the power conversion unit 30B. The value output from the power conversion output limiter 54 is output to the command value switching unit 30C as a normal operation command value.

  The SOC correction control unit 56 is a control unit for correcting the normal operation command value based on the SOC of the secondary battery 22.

  The SOC correction control unit 56 subtracts the detected SOC by a predetermined target SOC by the subtraction unit 62, multiplies the correction coefficient by the correction unit 64, and outputs the result to the addition unit 58.

  The operation of the SOC correction control unit 56 will be specifically described by comparing with or without the SOC correction control unit 56.

In the case where the SOC correction control unit 56 is not provided, for example, when the initial value of the smoothing filter 52 is “0” and the power generation output value is +100 kW from the reference value, the normal operation calculation unit 40 charges 100 kW. The normal operation command value for performing is output.
However, since this normal operation command value does not consider the SOC of the secondary battery 22, the amount of charge to the secondary battery 22 is excessive, and the secondary battery 22 may not be able to charge 100 kW.

On the other hand, when the SOC correction control unit 56 is provided and the target SOC is 50%, the detected SOC is 10%, and the correction coefficient is 100, the normal operation calculation unit 40 performs the normal operation command value for charging 60 kW. Is output.
This is a normal operation command value in consideration of the SOC of the secondary battery 22, and it is suppressed that the charging of the secondary battery 22 becomes excessive.

The disturbance suppression operation calculation unit 42 uses a disturbance suppression operation command value, which is a charge / discharge command value for the secondary battery 22 for suppressing system disturbance, based on a detected value of the system frequency (hereinafter referred to as “detection frequency”). calculate. The disturbance suppression operation calculation unit 42 continuously calculates a disturbance suppression operation command value regardless of whether or not a system disturbance has occurred.
Note that the disturbance suppression operation calculation unit 42 according to the present embodiment is provided in the power conversion controller 30A.

  The disturbance suppression operation calculation unit 42 includes a subtraction unit 70 and an IR calculation unit 72.

  The subtracting unit 70 outputs a difference (hereinafter referred to as “difference frequency”) obtained by subtracting a rated frequency (for example, 60 Hz) of the power system 14 from the detected frequency to the IR calculating unit 72.

The IR calculation unit 72 calculates a disturbance suppression operation command value S based on the following equation (1), and outputs it to the command value switching unit 30C.

In the above (1), K is a predetermined coefficient, Q is the rated capacity of the secondary battery 22, Delta] f is the difference frequency, F _R is the rated frequency.

  When the disturbance suppression operation command value is positive (+), a grid disturbance in which the grid frequency is higher than the rated frequency has occurred. In this case, the secondary battery 22 suppresses the system disturbance by charging. On the other hand, when the disturbance suppression operation command value is negative (−), a grid disturbance is generated in which the grid frequency is lower than the rated frequency. In this case, the secondary battery 22 suppresses the system disturbance by discharging.

  The disturbance suppression operation calculation unit 42 calculates the disturbance suppression operation command value based on the difference between the detected frequency and the rated frequency and the rated capacity of the secondary battery 22 as shown in the equation (1). Thus, since the calculation method of a disturbance suppression driving | operation command value is simple, the disturbance suppression driving | operation calculating part 42 can update a disturbance suppression driving | operation command value with a quick cycle. Specifically, the disturbance suppression operation calculation unit 42 updates the disturbance suppression operation command value at a cycle of, for example, 100 msec or less, and can cope with an intrinsic response due to charging / discharging of the secondary battery 22.

  Equation (1) is an example, and the difference frequency may be a difference between a value different from the rated frequency and the detection frequency. Further, the disturbance suppression operation command value may be calculated by another formula using the difference frequency. Further, table data indicating the relationship between the difference frequency and the disturbance suppression operation command value may be stored in advance, and the disturbance suppression operation command value corresponding to the difference frequency may be read from the table data.

The command value switching unit 30C is constantly input with the normal operation command value and the disturbance suppression operation command value regardless of whether the system disturbance has occurred. Then, the command value switching unit 30C selects one of the normal operation command value and the disturbance suppression operation command value and outputs it to the power conversion controller 30A. Whether or not system disturbance has occurred is determined based on the detected frequency.
Specifically, command value switching unit 30C outputs a normal operation command value to power conversion controller 30A when no system disturbance has occurred. On the other hand, when the disturbance occurrence condition indicating the system disturbance is satisfied, the command value switching unit 30C switches the normal operation command value to the disturbance suppression operation command value, and outputs it to the power conversion controller 30A.

As described above, the bidirectional power conversion device 30 according to the present embodiment constantly calculates the disturbance suppression operation command value for the secondary battery 22 regardless of the occurrence of the system disturbance. The charge / discharge command value of the secondary battery 22 can be switched to the disturbance suppression operation command value without delay.
As a result, the secondary battery 22 can sufficiently contribute to the suppression of fluctuations with respect to the initial response immediately after the occurrence of the system disturbance. The suppression of the fluctuation of the system frequency in the Inertial Response can improve the large frequency fluctuation in the Primary Frequency Response, and as a result, the fluctuation of the system frequency is suppressed in a short time.

  FIG. 3 is a flowchart showing a flow of operation switching processing of the secondary battery 22 executed by the command value switching unit 30C. The operation switching process is started together with the operation of the secondary battery 22, and when the operation of the secondary battery 22 is started, the normal operation mode using the normal operation command value is performed.

First, in step 100, it is determined whether or not the system frequency (detection frequency) satisfies the disturbance generation condition. If the determination is affirmative, the process proceeds to step 102, and if the determination is negative, the normal operation mode is continued (step 100). 108).
In the command value switching unit 30C according to the present embodiment, the system frequency is outside a predetermined range where no system disturbance occurs (hereinafter referred to as “non-disturbance range”), and the fluctuation rate of the system frequency is a predetermined value (hereinafter referred to as “disturbance”). It is determined that the disturbance occurrence condition is satisfied when the threshold is exceeded.

  With reference to FIG. 4, the disturbance generation conditions will be described.

  The system frequency varies to some extent. For this reason, even if the system frequency falls outside the non-disturbance range, it may return to the non-disturbance range immediately. In such a case, so-called hunting in which switching between the disturbance suppression operation command value and the normal operation command value is repeated may occur.

Therefore, the command value switching unit 30C switches the normal operation command value to the disturbance suppression operation command value when the system frequency is outside the non-disturbance range and the fluctuation rate of the system frequency is equal to or greater than the disturbance threshold. That is, even if the system frequency falls outside the non-disturbance range, if the fluctuation rate of the system frequency is less than the disturbance threshold, the system frequency immediately returns to the non-disturbance range, so that no system disturbance has occurred.
Therefore, the bidirectional power converter 30 according to the present embodiment can prevent the switching between the disturbance suppression operation command value and the normal operation command value from being repeated.

  As shown in FIG. 4, the non-disturbance range is a dead body, and the normal operation mode is continued even when the fluctuation rate of the system frequency is equal to or greater than the disturbance threshold. Even if the system frequency is outside the non-disturbance range, the normal operation mode is continued if the fluctuation rate is less than the disturbance threshold.

  When the rated frequency is 60 Hz, the non-disturbance range is, for example, 60 Hz ± 0.036 Hz, and the disturbance threshold is, for example, 0.05 Hz / sec.

  In addition, since the command value switching unit 30C detects the system frequency at a period of several milliseconds and detects the system disturbance only by the fluctuation of the system frequency, it can determine whether or not the system disturbance has occurred in a short time. Further, the command value switching unit 30C does not detect the absolute value of the system voltage, but only the system frequency, and therefore can detect the system disturbance easily and without erroneous detection.

  In step 102, the charge / discharge command value for the secondary battery 22 is switched from the normal operation command value to the disturbance suppression operation command value. As a result, the operation of the secondary battery 22 is switched from the normal operation mode to the disturbance suppression operation mode.

In the next step 104, it is determined whether or not the disturbance suppression release condition is satisfied. If the determination is affirmative, the process proceeds to step 108. If the determination is negative, the process proceeds to step 106.
The command value switching unit 30C according to the present embodiment suppresses disturbance when the secondary battery 22 is in a discharged state and below a predetermined SOC, or when the secondary battery 22 is in a charged state and becomes above a predetermined SOC. It is determined that the release condition is satisfied.

  In step 108, the charge / discharge command value for the secondary battery 22 is switched from the disturbance suppression operation command value to the normal operation command value. Thereby, the operation of the secondary battery 22 is switched from the disturbance suppression operation mode to the normal operation mode.

The secondary battery 22 promotes deterioration even if the SOC becomes too high or too low. That is, the predetermined SOC is an SOC whose deterioration is promoted when the secondary battery 22 is in a discharged state, and is deteriorated when the secondary battery 22 is charged in a charged state. The promoted SOC.
As described above, the bidirectional power conversion device 30 according to the present embodiment prioritizes the SOC state of the secondary battery 22 and switches to the normal operation mode even in the disturbance suppression operation mode. Deterioration can be suppressed.

  In step 106, it is determined whether or not the disturbance suppression condition is satisfied. If the determination is affirmative, the process proceeds to step 108. On the other hand, in the case of negative determination, the process proceeds to step 104, and the determinations in step 104 and step 106 are repeated while remaining in the disturbance suppression operation mode.

In the command value switching unit 30 </ b> C according to the present embodiment, the system frequency is within a predetermined range (hereinafter referred to as “disturbance suppression range”) indicating suppression of system disturbance, and is referred to as “disturbance suppression duration”. ) When the above is continued, or when the fluctuation rate of the system frequency is equal to or less than the disturbance suppression threshold smaller than the disturbance threshold, it is determined that the disturbance suppression condition is satisfied.
Note that the disturbance suppression range may be the same as or different from the non-disturbance range.

System disturbance is suppressed while repeating fluctuations in the system frequency. For this reason, even if the system frequency falls within the disturbance suppression range indicating suppression of the system disturbance, it may be immediately outside the disturbance suppression range. In such a case, hunting in which switching between the disturbance suppression operation command value and the normal operation command value is repeated may occur.
Therefore, the command value switching unit 30C switches the disturbance suppression operation command value to the normal operation command value when the system frequency is within the disturbance suppression range for more than the disturbance suppression duration time. That is, even if the system frequency falls within the disturbance suppression range, if the state does not continue, the disturbance is not suppressed.

In addition, the command value switching unit 30C switches to the normal operation command value when the fluctuation rate of the system frequency is greater than the disturbance threshold and equal to or less than the disturbance suppression threshold.
As described above, the disturbance suppression threshold according to the present embodiment is provided with a margin for the disturbance threshold, so that the switching between the disturbance suppression operation command value and the normal operation command value is prevented from being repeated.

  In the example of FIG. 5, in the region A, the fluctuation rate of the system frequency exceeds the disturbance suppression threshold, so that the disturbance suppression operation mode is continued. In region B, since the fluctuation rate of the system frequency is equal to or less than the disturbance suppression threshold, the disturbance suppression operation mode is switched to the normal operation mode. Even in the region C, since the system frequency is within the disturbance suppression range for more than the disturbance suppression duration, the disturbance suppression operation mode is switched to the normal operation mode.

  When the rated frequency is 60 Hz, the disturbance suppression range is, for example, 60 Hz ± 0.015 Hz, the disturbance suppression duration is, for example, 5 seconds, and the disturbance suppression threshold is 0.08 Hz / sec.

  The operation switching process is repeated until the operation of the secondary battery 22 is stopped by returning to step 100 after switching the charge / discharge command value from the disturbance suppression operation command value to the normal operation command value in step 108. .

As described above, the charge / discharge control device 11 according to the present embodiment uses the disturbance suppression operation command value, which is the charge / discharge command value for the secondary battery 22 for suppressing the system disturbance, based on the detected value of the system frequency. When the disturbance generation condition indicating the occurrence of the system disturbance is satisfied, the charge / discharge command value for the secondary battery 22 is switched from the normal operation command value to the disturbance suppression operation command value.
Therefore, the bidirectional power conversion device 30 according to the present embodiment can start the suppression of the disturbance immediately after the occurrence of the system disturbance, and can suppress the fluctuation of the system frequency in a short time.

  As mentioned above, although this invention was demonstrated using the said embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various changes or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which the changes or improvements are added are also included in the technical scope of the present invention.

For example, in the above embodiment, the form in which the generator 20 is connected to the local system 12 has been described. However, the present invention is not limited to this, and as shown in FIG. The machine 20 may not be connected.
In the case of this form, the normal operation calculation unit 40 may be provided in, for example, an EMS (Energy Management System) provided in the power system 14, and the normal operation command value may be input to the bidirectional power conversion device 30.

  Further, in the above-described embodiment, although the system frequency is outside the non-disturbance range and the variation rate of the system frequency is equal to or greater than the disturbance threshold, the embodiment has been described that determines that the disturbance generation condition is satisfied. It is not limited to this. For example, it is good also as a form which makes a disturbance generation condition only that the fluctuation rate of a system frequency becomes more than a disturbance threshold, or makes a disturbance generation condition another condition. Moreover, it is good also as a form which makes a disturbance suppression condition another condition.

  The flow of the operation switching process described in the above embodiment is also an example, and unnecessary steps are deleted, new steps are added, and the processing order is changed within a range not departing from the gist of the present invention. May be.

DESCRIPTION OF SYMBOLS 10 Electric power system 11 Charging / discharging control apparatus 14 Electric power system 22 Secondary battery 30 Bidirectional power converter (power conversion means)
30C Command value switching unit 40 Normal operation calculation unit (normal operation calculation means)
42 Disturbance suppression operation calculation unit (disturbance suppression operation calculation means)

Claims (7)

A charge / discharge control device for controlling charge / discharge of a secondary battery connected to the power system via power conversion means for converting DC power and AC power,
Normal operation calculation means for calculating a normal operation command value which is a charge / discharge command value for the secondary battery for stabilizing the power supplied to the power system;
Disturbance suppression operation calculation means for calculating a disturbance suppression operation command value, which is a charge / discharge command value for the secondary battery for suppressing disturbance of the power system, based on a detected value of the frequency of the power system;
A switching means for switching a charge / discharge command value for the secondary battery from the normal operation command value to the disturbance suppression operation command value when a disturbance generation condition indicating the occurrence of the disturbance is satisfied;
A charge / discharge control apparatus comprising:   The disturbance control operation command value is calculated based on a difference between a detected value of the frequency of the power system and a rated frequency of the power system and a rated capacity of the secondary battery. Charge / discharge control device.   3. The fulfillment according to claim 1, wherein the disturbance generation condition is outside a predetermined range in which the frequency of the power system does not generate a disturbance, and a fluctuation rate of the frequency of the power system is not less than a first predetermined value. Discharge control device.   The switching means is configured to change a charge / discharge command value for the secondary battery from the disturbance suppression operation command value when a variation rate of the frequency of the power system is equal to or less than a second predetermined value that is smaller than the first predetermined value. The charge / discharge control device according to claim 3, wherein the charge / discharge control device switches to the normal operation command value.   The switching means is configured to charge / discharge the secondary battery when the secondary battery is in a discharged state and below a predetermined charging rate, or when the secondary battery is in a charging state and becomes a predetermined charging rate or higher. The charge / discharge control apparatus according to any one of claims 1 to 4, wherein the command value is switched from the disturbance suppression operation command value to the normal operation command value.   The switching means, when the frequency of the power system is within a predetermined range indicating suppression of the disturbance for a predetermined time or longer, the charge / discharge command value for the secondary battery from the disturbance suppression operation command value The charge / discharge control device according to claim 1, wherein the charge / discharge control device is switched to a normal operation command value. A charge / discharge control method for controlling charge / discharge of a secondary battery connected to a power system through power conversion means for converting DC power and AC power,
A first step of calculating a normal power command value that is a charge / discharge command value for the secondary battery for stabilizing the power supplied to the power system;
A second step of calculating a disturbance suppression operation command value, which is a charge / discharge command value for the secondary battery for suppressing disturbance of the power system, based on a detected value of the frequency of the power system;
A third step of switching a charge / discharge command value for the secondary battery from the normal operation command value to the disturbance suppression operation command value when a disturbance generation condition indicating the occurrence of the disturbance is satisfied;
Charge / discharge control method.

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