JP6724612B2 - Output smoothing device and output smoothing method - Google Patents

Description

The present invention relates to an output smoothing device and an output smoothing method.

In recent years, the construction and grid interconnection of power generation plants that utilize renewable energy (RE) such as solar light (PhotoVoltaic: PV) and wind power (Wind Turbine: WT) have been activated. However, in power generation using renewable energy, it is difficult for a person to directly control the amount of power generation, and the influence of the weather can cause the output to change significantly. It is known that when the renewable energy power generation plant is connected to a commercial system, the output fluctuation may disrupt the supply and demand balance in the system and adversely affect the voltage and frequency in the system. Therefore, a renewable energy power plant that is connected to a commercial grid is required to have a function of smoothing output fluctuations.

An output smoothing device that sequentially calculates a moving average value of the amount of power generation of a renewable energy power generation device and sets a control target value of electric power at a grid interconnection point based on the calculated moving average value is known (for example, See Patent Document 1). In such an output smoothing device, when the power generation amount of the renewable energy power generation device is larger than the control target value, the excess amount is charged in the power storage device, and the power generation amount of the renewable energy power generation device is higher than the control target value. If is smaller, the shortage is discharged from the power storage device.

Japanese Patent No. 4170565

The amount of power generated by a renewable energy power generation device may fluctuate rapidly depending on the climate. However, in the above-described output smoothing device, the control target value cannot be changed significantly from the viewpoint of output smoothing at the grid interconnection point, so the difference between the power generation amount and the control target value is large over a long period of time. Become. In preparation for such a case, the renewable energy power generation plant needs to be provided with a large-capacity power storage device.

The present invention provides an output smoothing device and an output smoothing method capable of reducing the capacity of a power storage device.

An output smoothing device according to one aspect of the present invention includes a renewable energy power generation device, a power conversion device that converts electric power generated by the renewable energy power generation device, and a power storage device provided on the output side of the power conversion device. Is an output smoothing device that smoothes the output of a power generation system including. This output smoothing device includes a power generation amount acquisition unit that acquires a first measurement value that is a power generation amount that is the amount of power generated by a renewable energy power generation device, and a power generation amount that is based on the first measurement value. A change rate calculation unit that calculates a change rate, and a command value calculation unit that calculates an output command value for defining the upper limit value of the amount of electric power output from the power converter based on the change rate, Prepare

In this output smoothing device, the rate of change of the power generation amount is calculated based on the first measurement value obtained by measuring the power generation amount of the renewable energy power generation device, and the output power output from the power conversion device is calculated based on the change rate. The output command value that defines the upper limit value of the electric power of is calculated. Since the rate of change in the amount of power generation can be grasped from the rate of change in the amount of power generation, the output command value can be calculated so as to reduce the output fluctuation of the power conversion device according to the tendency of the increase or decrease in the amount of power generation. .. For example, when it is predicted that the power generation amount will suddenly decrease, the output command value is calculated so that the power amount of the output power of the power conversion device is not rapidly decreased, and when the power generation amount is rapidly increasing, the power conversion is performed. The output command value can be calculated so as not to cause a sudden increase in the amount of output power of the device. As a result, the amount of electric power that the power storage device has to charge and discharge for smoothing the output of the power generation system can be reduced, so that the capacity of the power storage device can be reduced.

The change rate calculation unit may calculate the first change rate, which is the change rate based on the predicted value of the power generation amount. The command value calculation unit may calculate the output command value so as to reduce the power amount of the output power by the first power amount when the first change rate is smaller than the first threshold value. When the first rate of change is smaller than the first threshold value, it is predicted that the power generation amount will suddenly decrease. Therefore, by decreasing the output command value by the first power amount before the power generation amount sharply decreases, the power amount of the output power of the power conversion device is reduced while suppressing the fluctuation of the power amount of the output power of the power conversion device. Can be reduced. Then, by reducing the amount of output power of the power conversion device in advance, it is possible to prevent the amount of output power of the power conversion device from being sharply reduced when the amount of power generation is sharply reduced. Accordingly, the amount of electric power that should be discharged from the power storage device for smoothing the output of the power generation system can be reduced, and thus the capacity of the power storage device can be reduced.

The change rate calculation unit may calculate a second change rate that is a change rate based on the first measurement value. The command value calculation unit may calculate the output command value so as to increase the power amount of the output power by the second power amount when the second change rate is larger than the second threshold value. When the second rate of change is larger than the second threshold value, it can be considered that the amount of power generation is rapidly increasing. At this time, by increasing the output command value by the second power amount, it is possible to prevent the power amount of the output power of the power converter from being sharply increased even if the power generation amount sharply increases. That is, it is possible to increase the amount of output power of the power conversion device while suppressing fluctuations in the amount of output power of the power conversion device. As a result, the amount of power to be charged in the power storage device for smoothing the output of the power generation system can be reduced, so that the capacity of the power storage device can be reduced.

The output smoothing apparatus described above includes a power amount acquisition unit that acquires a second measurement value obtained by measuring the amount of output power, and a control target value calculation unit that calculates a control target value that is a target value of the output of the power generation system. , May be further provided. In this case, the control target value is calculated according to the amount of output power of the power converter. Accordingly, it is possible to smooth the output of the power generation system while reducing the capacity of the power storage device.

An output smoothing method according to another aspect of the present invention includes a renewable energy power generation device, a power conversion device that converts electric power generated by the renewable energy power generation device, and a power storage device provided on the output side of the power conversion device. And an output smoothing method executed by an output smoothing device that smoothes the output of a power generation system including. This output smoothing method includes a step of obtaining a first measurement value obtained by measuring a power generation amount that is the amount of power generated by a renewable energy power generation device, and a change rate of the power generation amount based on the first measurement value. The step of calculating and the step of calculating an output command value for defining the upper limit value of the electric energy of the output electric power output from the power conversion device based on the change rate are included.

In this output smoothing method, the rate of change in the amount of power generation is calculated based on the first measurement value obtained by measuring the amount of power generated by the renewable energy power generation device, and the output power output from the power conversion device is calculated based on the rate of change. The output command value that defines the upper limit value of the electric power of is calculated. Since the rate of change in the amount of power generation can be grasped by the rate of change in the amount of power generation, the output command value can be calculated so as to reduce the output fluctuation of the power converter according to the tendency of the increase or decrease in the amount of power generation. .. For example, when it is predicted that the power generation amount will suddenly decrease, the output command value is calculated so that the power amount of the output power of the power conversion device is not rapidly decreased, and when the power generation amount is rapidly increasing, the power conversion is performed. The output command value can be calculated so as not to cause a sudden increase in the amount of output power of the device. As a result, the amount of electric power that the power storage device has to charge and discharge for smoothing the output of the power generation system can be reduced, so that the capacity of the power storage device can be reduced.

According to the present invention, the capacity of the power storage device can be reduced.

It is a figure showing roughly the example of composition of the power generation system containing the output smoothing device concerning one embodiment. It is a figure which shows the function structure of the output smoothing apparatus of FIG. It is a figure which shows the hardware constitutions of the output smoothing apparatus of FIG. It is a flowchart which shows an example of the power conditioner control which the output smoothing apparatus of FIG. 1 performs. 3 is a flowchart showing an example of power storage device control executed by the output smoothing device of FIG. 1. It is a figure for demonstrating the smoothing process at the time of a rapid increase in the amount of power generation. It is a figure for demonstrating the smoothing process at the time of the sudden reduction of the amount of power generation. It is a figure for demonstrating the smoothing process of a comparative example at the time of the sudden reduction of the amount of power generation. It is a figure which shows schematically the modification of the electric power generation system of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a diagram schematically showing a configuration example of a power generation system including an output smoothing device according to an embodiment. As shown in FIG. 1, the power generation system 1 is a system that is connected to the commercial power grid 2 and supplies power to a connection point with the commercial power grid 2. The power generation system 1 includes a function (hereinafter, simply referred to as “smoothing of the output Ps”) for smoothing fluctuations in the amount of electric power at the interconnection point (hereinafter, referred to as “output Ps”). .. The power generation system 1 is, for example, a renewable energy power generation plant. The power generation system 1 includes a renewable energy power generation device 11, a power conditioner 12, a power meter 13, a power meter 14, a power meter 15, a power storage device 16, an inverter 17, a control device 18, and a control device. 19, an output smoothing device 20, and a power generation amount prediction system 30.

The renewable energy power generation device 11 is a device that generates electricity using renewable energy. In the renewable energy power generation device 11, its output, that is, the amount of power generation Pg may fluctuate. The renewable energy power generation device 11 is, for example, a solar power generator, a wind power generator, or the like. The renewable energy power generation device 11 outputs the generated DC power to the power conditioner 12 via the power line L1.

The power conditioner 12 is a power conversion device that converts the power generated by the renewable energy power generation device 11. The power conditioner 12 converts DC power from the renewable energy power generation device 11 into AC power (output power). The power conditioner 12 outputs the converted AC power to the commercial power system 2 via the power line L2.

The power meter 13 is a device that measures the power generation amount Pg of the renewable energy power generation device 11. The power generation amount Pg is the amount of DC power generated by the renewable energy power generation device 11. The power meter 13 continuously measures the power generation amount Pg of the renewable energy power generation device 11 in the power line L1, for example. The power meter 13 transmits the measured power generation amount Pg to the control device 18 and the output smoothing device 20.

The power meter 14 is a device that measures the power amount Pc of the AC power output from the power conditioner 12. The power meter 14 continuously measures the power amount Pc at a portion L21 between the power conditioner 12 and a position of the power line L2 to which the inverter 17 is connected, for example. The power meter 14 transmits the measured power amount Pc to the control device 18 and the output smoothing device 20.

The power meter 15 is a device that measures the output Ps. The power meter 15 continuously measures the output Ps of the power generation system 1 at a portion L22 between the commercial power system 2 and the position of the power line L2 to which the inverter 17 is connected, for example. The power meter 15 transmits the measured output Ps to the control device 19.

The power storage device 16 is a device capable of charging and discharging electric power. The power storage device 16 is, for example, a stationary storage battery. As the power storage device 16, for example, a lithium ion battery (LiB) can be used. The power storage device 16 is provided on the output side of the power conditioner 12 and is connected to the power line L2 via the inverter 17. Power storage device 16 is used for smoothing output Ps of power generation system 1. Specifically, the power storage device 16 charges and discharges so that the output Ps of the power generation system 1 becomes the control target value E ₂ . The charge/discharge of the power storage device 16 is controlled by the control device 19. The control target value E ₂ is a target value of the output Ps of the power generation system 1.

Inverter 17 is a device for connecting power storage device 16 to power line L2. Inverter 17 converts the DC power output from power storage device 16 into AC power and supplies the converted AC power to power line L2. Inverter 17 converts a part of the AC power flowing through power line L2 into DC power and outputs the converted DC power to power storage device 16.

The control device 18 determines the output (power amount Pc of AC power) of the power conditioner 12 based on the power amount Pc received from the power meter 14 and the output command value E ₁ received from the output smoothing device 20. It is a device that controls. The output command value E ₁ is a value for defining the upper limit value (maximum output) of the output of the power conditioner 12. The control device 18 controls the output of the power conditioner 12 so that the power amount Pc does not exceed the output command value E ₁ , for example. Specifically, the control device 18 adjusts the conversion efficiency of the power conditioner 12 so that the power amount Pc is smaller than the output command value E ₁ . The control device 18 adjusts the conversion efficiency of the power conditioner 12 by changing the drive frequency of the power conditioner 12, for example. The control device 18 may control the output of the power conditioner 12 so that the power amount Pc follows the output command value E ₁ .

Control device 19 is a device that controls charging and discharging of power storage device 16 based on output Ps received from power meter 15 and control target value E ₂ received from output smoothing device 20. The control device 19 controls the charge/discharge amount of the power storage device 16 so that the output Ps follows the control target value E ₂ , for example. As the follow-up control, for example, PID (Proportional-Integral-Derivative) control may be used. Specifically, the control device 19 subtracts the control target value E ₂ from the output Ps, and when the subtracted difference is a positive value (when the output Ps exceeds the control target value E ₂ ), The power storage device 16 is controlled so that the power storage device 16 is charged with surplus power that is the difference power. When the difference is a negative value (when the output Ps is below the control target value E ₂ ), the control device 19 causes the power storage device 16 to discharge the insufficient power, which is the power of the difference. Control 16 Note that a dead zone of about ±several% is provided for the control target value E ₂ so that the power storage device 16 does not repeat charging and discharging, and the control device 19 controls the power storage device 16 when the output Ps is in the dead band. It may not be charged and discharged.

The output smoothing device 20 is a device for smoothing the output Ps of the power generation system 1. The output smoothing device 20 outputs the output command value E ₁ and the control target value E ₂ so as to smooth the output Ps. Details of the output smoothing device 20 will be described later.

The power generation amount prediction system 30 is a system that predicts the power generation amount Pg of the renewable energy power generation device 11. A known method may be used to predict the power generation amount Pg. The power generation amount prediction system 30 predicts the power generation amount Pg by, for example, predicting a climate that is geographically local and that is a short time ahead of several tens of minutes to several hours. Specifically, the power generation amount prediction system 30 captures an image of the sky above the renewable energy power generation device 11 using a camera and analyzes the captured image. The power generation amount prediction system 30 predicts the amount of solar radiation by image analysis, and converts the predicted amount of solar radiation into a predicted value f~ of the amount of power generation by a known method. The power generation prediction system 30 may calculate the amount of solar radiation based on a numerical weather model. The power generation amount prediction system 30 outputs the predicted value f~ of the power generation amount to the output smoothing device 20.

Next, the output smoothing device 20 will be described in detail with reference to FIGS. 2 and 3. FIG. 2 is a diagram showing a functional configuration of the output smoothing device 20. FIG. 3 is a hardware configuration diagram of the output smoothing device 20. As shown in FIG. 2, the output smoothing device 20 functionally includes a power generation amount acquisition unit 21, a measurement data storage unit 22, a predicted value acquisition unit 23, a change rate calculation unit 24, and a command value. The calculation unit 25, the power amount acquisition unit 26, the measurement data storage unit 27, the control target value calculation unit 28, and the output unit 29 are provided.

As shown in FIG. 3, the output smoothing device 20 physically includes one or more processors 201 and a storage device such as a RAM (Random Access Memory) and a ROM (Read Only Memory) that are main storage devices. 202, an auxiliary storage device 203 such as a hard disk device, an input device 204 such as a keyboard, an output device 205 such as a display, and a communication device 206 that is a communication interface for transmitting and receiving data. It Each function shown in FIG. 2 of the output smoothing device 20 causes each hardware to operate under the control of the processor 201 by causing the hardware such as the processor 201 to read one or a plurality of predetermined computer programs. At the same time, it is realized by reading and writing data in the storage device 202 and the auxiliary storage device 203.

The power generation amount acquisition unit 21 functions as a power generation amount acquisition unit that acquires a measurement value p ₁ (first measurement value) obtained by measuring the power generation amount of the renewable energy power generation device 11. The power generation amount acquisition unit 21 acquires, for example, the power generation amount Pg output from the power meter 13 as the measurement value p ₁ at a predetermined sampling interval ΔT ₁ , and also acquires the time k _{1 at} which the measurement value p ₁ was measured. Hereinafter, the measurement value p ₁ at the time k ₁ is represented as the measurement value p ₁ (k ₁ ). The time _{k 1} is 0, 1, 2, ... is an integer, real time _{t 1} corresponding to the time _{k 1} is _{k 1} × [Delta] T _1. The reference time at which the real time t ₁ becomes 0 can be set to any control execution timing. The sampling interval ΔT ₁ is a control period of the power conditioner control described later, and is, for example, about 1 second to 10 seconds. Power generation amount acquisition unit 21 determines whether it has reached the time k _1, when it is determined to have reached the time k _1, acquires the measured value p _{1 (k 1)} and time k _1. The power generation amount acquisition unit 21 stores the acquired measurement value p ₁ (k ₁ ) and the time k _{1 in the} measurement data storage unit 22 as first measurement data in association with each other.

The measurement data storage unit 22 functions as a first measurement data storage unit that stores the first measurement data. The measurement data storage unit 22 stores a plurality of time-series first measurement data.

The predicted value acquisition unit 23 functions as a predicted value acquisition unit that acquires the predicted value f~ of the power generation amount. The predicted value acquisition unit 23 acquires the predicted value f~ at the predicted time h ahead from the power generation prediction system 30 at time k ₁ . Later, representing the predicted value f ~ the predicted value f ~ of the predicted time h destination of time _{k 1} and _(k 1 + h). The predicted time h is, for example, several ten minutes to one hour. The predicted value acquisition unit 23 outputs the acquired predicted values f to (k ₁ +h) to the change rate calculation unit 24.

The rate-of-change calculating unit 24 functions as a rate-of-change calculating unit that calculates the rate of change of the power generation amount Pg based on the measured value p ₁ (k ₁ ). The change rate calculation unit 24 calculates a change rate a ₁ (k ₁ ) (second change rate) that is a change rate based on the measured value p ₁ (k ₁ ). The change rate a ₁ (k ₁ ) is the change rate (change amount per unit time) of the power generation amount Pg at the time k ₁ . Specifically, the change rate calculation unit 24 approximates the trend of the measured value p ₁ (k ₁ ) at each time k ₁ (k ₁ =0, 1, 2,...) With a linear function with respect to time. The rate-of-change calculator 24 calculates the approximate function by using, for example, the least square method.

The rate-of-change calculation unit 24 calculates the approximate function value (smooth value) f(k ₁ ΔT ₁ ; a ₁ (k ₁ ), b ₁ (k) of the power generation amount Pg at time k ₁ as shown in equation (1) ₁ )) is calculated.

Here, the rate of change a ₁ (k ₁ ) and the intercept b ₁ (k ₁ ) are obtained by, for example, the least squares method, as shown in the equations (2) and (3). The number of data M ₁ used for the approximation is predetermined. The number M ₁ of data is, for example, several hundreds to several thousands.

Change rate calculating unit 24, the predicted value f ~ amount of power generation is a change rate based on the _(k 1 + h) change rate v ~; calculating a _(k 1 h) (first rate of change). The change rate v to (k ₁ ; h) is a predicted value of the change rate of the average power generation amount Pg from the time k ₁ to the time k ₁ +h. Change rate calculating section 24, as shown in equation (4), using the prediction value obtaining unit predicted value f ~ received from 23 _(k 1 + h), the approximate function from the predicted value f ~ _(k 1 + h) The value f(k ₁ ΔT ₁ ; a ₁ (k ₁ ), b ₁ (k ₁ )) is subtracted, and the subtraction result is divided by the time hΔT ₁ to obtain the change rate v~(k ₁ ; h). calculate. Since the variation of the measured value p ₁ (k ₁ ) is generally large, the approximate function value f(k ₁ ΔT ₁ ; a ₁ (k ₁ ) is used to calculate the rate of change v~(k ₁ ; h). , B ₁ (k ₁ )) are used.

The change rate calculation unit 24 calculates the approximate function value f(k ₁ ΔT ₁ ; a ₁ (k ₁ ), b ₁ (k ₁ )), the change rate a ₁ (k ₁ ), and the change rates v to (k ₁ ; h) is output to the command value calculation unit 25.

The command value calculation unit 25 functions as a command value calculation unit that calculates the output command value E ₁ based on the change rate. Command value calculating unit 25, for example, as shown in equation (5), calculates the output command value _{E 1} in the form of the output instruction value _E 1 _{(k 1)} at time _{k 1.} The threshold value-β (first threshold value) is a threshold value related to the rate of change v~(k ₁ ; h), and is a rate of decrease of the output Ps per unit time allowed for the commercial power system 2. The threshold value β (second threshold value) is a threshold value relating to the change rate a ₁ (k ₁ ) and is an increase rate per unit time of the output Ps allowed for the commercial power system 2. The threshold value-β and the threshold value β are set in advance and are, for example, change rates designated by the electric power company. Absolute values may be set to different values for the threshold values for change rates v to (k ₁ ; h) and the threshold values for change rate a ₁ (k ₁ ). The output E _max is the maximum output that the power conditioner 12 can output. The output command value E ₁ (0) at time 0 is set to the output E _max .

When the rate of change v~(k ₁ ; h) is smaller than the threshold value -β, it is predicted that the power generation amount Pg exceeding the threshold value β will suddenly decrease from the time k ₁ until the prediction time h elapses. In this case, the command value calculation unit 25 calculates the output command value E ₁ so as to reduce the output of the power conditioner 12 by the first power amount. Specifically, the command value calculating unit 25, the approximation function value f at time _{k 1 (k 1 ΔT 1;} a 1 (k 1), b 1 (k 1)) and the output command value at time _k 1 -1 The first electric energy is subtracted from the smaller _{one of} E ₁ (k ₁ -1), and the larger one of the subtraction result and 0 is set as the output command value E ₁ (k ₁ ). Since the output of the power conditioner 12 may be suppressed at the previous time k ₁ -1, the output command value E ₁ (k ₁ -1) is considered. Further, the subtraction result is compared with 0 so that the output command value E ₁ (k ₁ ) does not become a negative value. In this example, the first power amount is set to β×ΔT ₁ . That is, the command value calculation unit 25 reduces the output command value E ₁ (k ₁ ) at an allowable change rate. This alleviates the sudden decrease in the apparent power generation amount Pg.

When the rate of change v~(k ₁ ; h) is greater than or equal to the threshold value -β and the rate of change a ₁ (k ₁ ) is greater than the threshold value β, the command value calculation unit 25 starts the prediction time h from the time k _1. Although a sudden decrease in the power generation amount Pg exceeding the threshold β is not predicted until the time elapses, a rapid increase in the power generation amount Pg exceeding the threshold β occurs at the time k ₁ . In this case, the command value calculation unit 25 calculates the output command value E ₁ so as to increase the output of the power conditioner 12 by the second power amount. Specifically, the command value calculating unit 25, the approximation function value f at time _{k 1 (k 1 ΔT 1;} a 1 (k 1), b 1 (k 1)) and the output command value at time _k 1 -1 The second electric energy is added to the smaller one of E ₁ (k ₁ -1), and the smaller one of the addition result and the output E _max is set as the output command value E ₁ (k ₁ ). Since the output of the power conditioner 12 may be suppressed at the previous time k ₁ -1, the output command value E ₁ (k ₁ -1) is considered. Also, the output instruction value _{E 1 (k} 1) is so as not to exceed the output _{E max,} compared with the output _{E max} and the addition result is performed. In this example, the second power amount is set to β×ΔT ₁ . That is, the command value calculation unit 25 increases the output command value E ₁ (k ₁ ) at an allowable rate of change. This alleviates the sudden increase in the apparent power generation amount Pg.

When the rate of change v~(k ₁ ; h) is greater than or equal to the threshold value-β and the rate of change a ₁ (k ₁ ) is less than or equal to the threshold value β, the command value calculation unit 25 predicts the predicted time h from the time k _1. A sudden decrease in the power generation amount Pg exceeding the threshold β is not predicted until the time elapses, and there is no sudden increase in the power generation amount Pg exceeding the threshold β at time k ₁ . In this case, the command value calculation unit 25 adds the second power amount to the output command value E ₁ (k ₁ -1), and the smaller one of the addition result and the output E _max is the output command value E ₁ (k. ₁ ). That is, the command value calculation unit 25 increases the output command value E ₁ (k ₁ ) within the range of the output E _max or less at an allowable change rate.

In addition, as shown in the equation (5), priority is given to the case where the sudden decrease in the power generation amount Pg is predicted. For example, even if surge of power generation amount Pg exceeding the threshold β is generated at time k _1, when the rapid decrease of the power generation amount Pg exceeding a threshold β during the period from the time k ₁ until the predicted time h elapses is predicted is in anticipation of the rapid decrease of the power generation amount Pg, approximation function value f at time _{k 1 (k 1 ΔT 1;} a 1 (k 1), b 1 (k 1)) and the time _k 1 output command value at -1 E The first electric energy is subtracted from the smaller one of ₁ (k ₁ -1) and the result of the subtraction is the output command value E ₁ (k ₁ ). The command value calculation unit 25 outputs the calculated output command value E ₁ (k ₁ ) to the output unit 29.

Further, with respect to the rapid increase in the power generation amount Pg, the increase rate of the output command value E ₁ (k ₁ ) is suppressed even after the rapid change in the power generation amount Pg is recognized based on the current change rate a ₁ (k ₁ ). Is possible. On the other hand, with respect to the sudden decrease in the power generation amount Pg, the output command value E ₁ (k ₁ ) decreases in accordance with the rapid decrease in the power generation amount Pg. Therefore, the current change rate a ₁ (k ₁ ) causes At the stage of recognition, it is difficult to respond. Thus, by predicting the rapid decrease of the power generation amount Pg, while suppressing the decrease rate of the output command value _{E 1 (k} 1), the output command value _{E 1 (k} 1) is gradually reduced.

The power amount acquisition unit 26 functions as a power amount acquisition unit that acquires a measurement value p ₂ (second measurement value) obtained by measuring the power amount of the AC power output from the power conditioner 12. The power amount acquisition unit 26 acquires, for example, the power amount Pc output from the power meter 14 as the measurement value p ₂ at a predetermined sampling interval ΔT ₂ , and also acquires the time k _{2 at} which the measurement value p ₂ was measured. Hereinafter, the measurement value p ₂ at time k ₂ will be referred to as a measurement value p ₂ (k ₂ ). The time _{k 2} is 0, 1, 2, ... is an integer, real time _{t 2} corresponding to the time _{k 2} is the _{k 2} × [Delta] T _2. The reference time at which the real time t ₂ becomes 0 can be set to any control execution timing. The sampling interval ΔT ₂ is a control cycle of power storage device control described later, and is, for example, about 1 second to 10 seconds. Power amount obtaining unit 26 determines whether it has reached the time k _2, if it is determined to have reached the time k _2, acquires the measured value p _{2 (k 2)} and the time k _2. The power amount acquisition unit 26 stores the acquired measurement value p ₂ (k ₂ ) and the time k ₂ in association with each other in the measurement data storage unit 27 as the second measurement data.

The measurement data storage unit 27 functions as a second measurement data storage unit that stores the second measurement data. The measurement data storage unit 27 stores a plurality of time-series second measurement data.

The control target value calculation unit 28 functions as control target value calculation means for calculating the control target value E ₂ . A known method can be used for calculating the control target value E ₂ . Here, a method of calculating the control target value E ₂ by approximating the measured value p ₂ (k ₂ ) with a linear function, as with the output command value E ₁ , will be described. The control target value calculation unit 28 approximates the trend of the measured value p ₂ (k ₂ ) at each time k ₂ (k ₂ =0, 1, 2,...) With a linear function with respect to time, for example. The control target value calculation unit 28 calculates an approximate function using, for example, the least square method.

The control target value calculation unit 28 calculates the approximate function value (smooth value) f(k ₂ ΔT ₂ ; a ₂ (k ₂ ), b ₂ (of the power amount Pc at the time k ₂ as shown in the equation (6). k ₂ )) is calculated.

Here, the rate of change a ₂ (k ₂ ) and the intercept b ₂ (k ₂ ) are obtained by, for example, the least squares method, as shown in Expressions (7) and (8). The number M ₂ of data used for the approximation is predetermined. The number M ₂ of data is, for example, several hundreds to several thousands.

The control target value calculation unit 28 sets the approximate function value f(k ₂ ΔT ₂ ; a ₂ (k ₂ ), b ₂ (k ₂ )) to the control target value E ₂ that is the control target value E ₂ at time k ₂ . Set to (k ₂ ). The control target value calculation unit 28 outputs the calculated control target value E ₂ (k ₂ ) to the output unit 29.

The output unit 29 transmits the output command value E ₁ (k ₁ ) calculated by the command value calculation unit 25 to the control device 18, and the control target value E ₂ (k ₂ calculated by the control target value calculation unit 28. ) To the control device 19 and functions as an output unit. When the output unit 29 receives the output command value E ₁ (k ₁ ) from the command value calculation unit 25, the output unit 29 transmits the received output command value E ₁ (k ₁ ) to the control device 18. Upon receiving the control target value E ₂ (k ₂ ) from the control target value calculation unit 28, the output unit 29 transmits the received control target value E ₂ (k ₂ ) to the control device 19.

Whether the power generation amount acquisition unit 21, the predicted value acquisition unit 23, the change rate calculation unit 24, the command value calculation unit 25, and the output unit 29 respectively indicate that the control continuation flag of the power conditioner control indicates continuation of the power conditioner control. Each process may be performed when it is determined whether or not the control continuation flag indicates continuation of the power conditioner control. The power amount acquisition unit 26, the control target value calculation unit 28, and the output unit 29 each determine whether or not the control continuation flag of the power storage device control indicates continuation of the power storage device control, and the control continuation flag indicates that the power storage device control. Each process may be performed when the continuation of is indicated.

Next, a series of processes of the output smoothing method executed by the output smoothing apparatus 20 will be described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart showing an example of the power conditioner control executed by the output smoothing device 20. FIG. 5 is a flowchart showing an example of the power storage device control executed by the output smoothing device 20. The processes shown in FIGS. 4 and 5 may be started, for example, in response to the activation of the output smoothing device 20, or may be repeatedly started at predetermined time intervals.

In the power conditioner control shown in FIG. 4, first, the power generation amount acquisition unit 21 determines whether or not the control continuation flag indicates continuation of the power conditioner control (step S11). In step S11, when the control continuation flag is determined to indicate the continuation of the power conditioner control (step S11; Yes), the power generation amount acquisition unit 21, the time k ₁ is an update time of the output command value E ₁ It is determined whether or not (step S12). In step S12, if it is determined not to reach the time _{k 1} (step S12; No), the determination of step S11 is performed again. On the other hand, in step S12, if it is determined to have reached the time _{k 1} (step S12; Yes), the power generation amount acquisition unit 21 acquires the amount of power generation Pg as a measurement value _{p 1 (k} 1) from the power meter 13 At the same time, the time k _{1 at} which the measurement value p ₁ (k ₁ ) is measured is acquired. Then, the power generation amount acquisition unit 21 stores the acquired measurement value p ₁ (k ₁ ) and the time k ₁ in association with each other in the measurement data storage unit 22 as the first measurement data (step S13).

Subsequently, the change rate calculating unit 24 determines whether or not the first measurement data of the data number M ₁ or more is stored in the measurement data storage unit 22 (step S14). When it is determined in step S14 that the first measurement data of less than the data number M ₁ is stored in the measurement data storage unit 22 (step S14; No), the determination of step S11 is performed again. On the other hand, in step S14, when it is determined that the first measurement data of the data number M ₁ or more is stored in the measurement data storage unit 22 (step S14; Yes), the change rate calculation unit 24 stores the measurement data. The first measurement data of the latest data number M ₁ is extracted as time series data from the first measurement data stored in the unit 22 (step S15).

Subsequently, the change rate calculation unit 24 calculates the change rate a ₁ (k ₁ ) using the time-series data extracted in step S15 (step S16). Specifically, the change rate calculation unit 24 calculates the change rate a ₁ (k ₁ ) by the least squares method using the time series data, as shown in Expression (2). Further, the change rate calculating unit 24 calculates the intercept b ₁ (k ₁ ) by the least squares method using the time series data, as shown in Expression (3). Then, the change rate calculating unit 24, as shown in the equation (1), approximate function value f(k ₁ ΔT ₁ ; a ₁ (k ₁ ), b ₁ (k ₁ ) of the power generation amount Pg at the time k ₁ . ) Is calculated. Then, the change rate calculation unit 24 outputs the approximate function value f(k ₁ ΔT ₁ ; a ₁ (k ₁ ), b ₁ (k ₁ )) and the change rate a ₁ (k ₁ ) to the command value calculation unit 25. To do.

Subsequently, the predicted value acquisition unit 23 acquires the predicted value f to (k ₁ +h) ahead of the predicted time h from the power generation prediction system 30 at time k ₁ (step S17). Then, the predicted value acquisition unit 23 outputs the acquired predicted values f to (k ₁ +h) to the change rate calculation unit 24.

Subsequently, the change rate calculating section 24, based on the predicted value f ~ acquired in step S17 _(k 1 + h), the change rate v ~; calculating a _(k 1 h) _(step S18). Specifically, the change rate calculating section 24, as shown in equation (4), using the prediction value _{f ~ (k 1 + h)} , the change rate v ~; calculating a _(k 1 h). Then, the change rate calculation unit 24 outputs the change rate v~(k ₁ ; h) to the command value calculation unit 25.

Subsequently, the command value calculation unit 25 outputs the output command value E ₁ based on the change rate a ₁ (k ₁ ) calculated in step S16 and the change rate v to (k ₁ ; h) calculated in step S18. Is calculated (step S19). Specifically, the command value calculation unit 25 calculates the output command value E ₁ (k ₁ ) as shown in equation (5). Then, the command value calculation unit 25 outputs the calculated output command value E ₁ (k ₁ ) to the output unit 29.

Subsequently, the output unit 29 transmits the calculated output command value _E 1 a _{(k 1)} to the control device 18 in step S19 (step S20), the determination of step S11 is performed again. When it is determined in step S11 that the control continuation flag indicates the stop of the power conditioner control (step S11; No), the series of processes of the power conditioner control ends. Note that step S11 is not limited to being performed before step S12, and may be performed before each step.

As described above, in the power conditioner control, the output of the power conditioner 12 is appropriately suppressed based on the rate of change a ₁ (k ₁ ) and the rates of change v to (k ₁ ; h). As a result, the roughly smoothed AC power having the power amount Pc is output from the power conditioner 12.

In the power storage device control illustrated in FIG. 5, first, the power amount acquisition unit 26 determines whether the control continuation flag indicates continuation of the power storage device control (step S31). When it is determined in step S31 that the control continuation flag indicates continuation of the power storage device control (step S31; Yes), the power amount acquisition unit 26 sets the control target value E ₂ at time k ₂ that is the update time. It is determined whether it has reached (step S32). In step S32, if it is determined not to reach the time _{k 2} (step S32; No), the determination of step S31 is performed again. On the other hand, in step S32, if it is determined to have reached the time _{k 2} (step S32; Yes), the power amount acquisition section 26 acquires a power amount Pc from the power meter 14 as a measurement value _{p 2 (k} 2) At the same time, the time k _{2 at} which the measurement value p ₂ (k ₂ ) is measured is acquired. Then, the power amount acquisition unit 26 stores the acquired measurement value p ₂ (k ₂ ) and the time k ₂ in association with each other in the measurement data storage unit 27 as the second measurement data (step S33).

Then, the control target value calculation unit 28 determines whether or not the second measurement data of the data number M ₂ or more is stored in the measurement data storage unit 27 (step S34). When it is determined in step S34 that the second measurement data of which the number of data is less than M ₂ is stored in the measurement data storage unit 27 (step S34; No), the determination of step S31 is performed again. On the other hand, when it is determined in step S34 that the second measurement data having the data number M ₂ or more is stored in the measurement data storage unit 27 (step S34; Yes), the control target value calculation unit 28 determines the measurement data. From the second measurement data stored in the storage unit 27, the latest measurement number M ₂ of second measurement data is extracted as time-series data (step S35).

Subsequently, the control target value calculation unit 28 approximates the trend of the measured value p ₂ (k ₂ ) with a linear function with respect to time (step S36). Specifically, the control target value calculation unit 28 uses the least-squares method using the time-series data extracted in step S35, as shown in equations (7) and (8), to calculate the change rate a ₂ ( k ₂ ) and the intercept b ₂ (k ₂ ) are calculated. Then, the control target value calculation unit 28, as shown in Expression (6), approximate function value f(k ₂ ΔT ₂ ; a ₂ (k ₂ ), b ₂ (k ₂ ) of the power amount Pc at the time k ₂ . )) is calculated.

Subsequently, the control target value calculation unit 28 sets the approximate function value f(k ₂ ΔT ₂ ; a ₂ (k ₂ ), b ₂ (k ₂ )) to the control target value E ₂ (k ₂ ) (step S37). Then, the control target value calculation unit 28 outputs the calculated control target value E ₂ (k ₂ ) to the output unit 29.

Subsequently, the output unit 29 transmits the calculated control target value _{E 2 (k} 2) to the controller 19 in step S37 (step S38), the determination of step S31 is performed again. When it is determined in step S31 that the control continuation flag indicates that the power storage device control is stopped (step S31; No), a series of processes of the power storage device control ends. Note that step S31 is not limited to being performed before step S32, and may be performed before each step.

As described above, in the power storage device control, the output Ps is finely smoothed by charge/discharge control of the power storage device 16 after rough smoothing is performed by the power conditioner control.

Next, the operation and effect of the output smoothing device 20 and the output smoothing method performed by the output smoothing device 20 will be described with reference to FIGS. FIG. 6 is a diagram for explaining the smoothing process when the power generation amount Pg rapidly increases. FIG. 7 is a diagram for explaining the smoothing process when the power generation amount Pg is sharply reduced. FIG. 8 is a diagram for explaining the smoothing process of the comparative example when the power generation amount Pg is sharply reduced. 6 to 8, the horizontal axis represents time and the vertical axis represents power (quantity).

In the comparative example shown in FIG. 8, the output Ps is smoothed by the discharge of the power storage device with respect to the sudden decrease in the power generation amount Pg. In this case, the power storage device needs to discharge a power amount corresponding to the difference between the output Ps (control target value E ₂ ) and the power generation amount Pg (a region surrounded by the output Ps and the power generation amount Pg in FIG. 8 ). .. Similarly, when the power generation amount Pg rapidly increases, the power storage device needs to charge the power amount corresponding to the difference between the output Ps (control target value E ₂ ) and the power generation amount Pg. Therefore, it is necessary to increase the capacity of the power storage device to such an extent that charging/discharging is possible, which increases the cost of the power storage device.

On the other hand, as shown in FIG. 6, in the output smoothing device 20, the power amount Pc of the AC power output from the power conditioner 12 is sequentially suppressed when the power generation amount Pg rapidly increases. This apparently alleviates the sudden increase in the power amount Pc. Further, as shown in FIG. 7, in the output smoothing device 20, when the power generation amount Pg sharply decreases, the power amount Pc of the AC power output from the power conditioner 12 is predicted at the time when the power generation amount Pg is predicted to sharply decrease. It is suppressed in advance. This apparently alleviates the sudden decrease in the power amount Pc.

As described above, in the output smoothing device 20, the output of the power conditioner 12 is suppressed by setting the output command value E ₁ in accordance with the sudden increase or the sudden decrease of the power generation amount Pg. Thereby, the fluctuation of the power generation amount Pg is smoothed to some extent, and the power amount Pc is obtained. Then, with respect to the fluctuation of the electric power amount Pc caused by the sudden sudden increase and the sudden decrease of the electric power generation amount Pg which cannot be predicted, the difference between the control target value E ₂ and the electric power amount Pc depends on the charging/discharging of the power storage device 16. By being supplemented, the output Ps is smoothed. Therefore, as compared with the comparative example shown in FIG. 8, the capacity of power storage device 16 can be reduced, and the construction cost of power generation system 1 can be reduced.

As described above, in the output smoothing device 20 and the output smoothing method, the change in the power generation amount at time k ₁ is based on the measured value p ₁ (k ₁ ) of the power generation amount of the renewable energy power generation device 11. The rate a ₁ (k ₁ ) and the rate of change v ~ (k ₁ ; h) from the time k ₁ until the prediction time h elapses are calculated, and the rate of change a ₁ (k ₁ ) and the rate of change v ~ Based on (k ₁ ; h), the output command value E ₁ (k ₁ ) that defines the upper limit value of the electric power amount Pc of the AC power output from the power conditioner 12 is calculated. Since the change rate a ₁ (k ₁ ) and the change rates v to (k ₁ ; h) can be used to grasp the trend (trend) of the increase or decrease in the power generation amount Pg, the power generation amount Pg can be changed in accordance with the increase or decrease tendency. , The output command value E ₁ (k ₁ ) is calculated so as to reduce the output fluctuation of the power conditioner 12 (the fluctuation of the electric energy Pc). When it is predicted that the power generation amount Pg sharply decreases, the output command value E ₁ (k ₁ ) is calculated so that the power amount Pc of the AC power output from the power conditioner 12 is not sharply reduced, and the power generation amount Pg In the case where the electric power amount Pc is rapidly increasing, the output command value E ₁ (k ₁ ) is calculated so that the electric power amount Pc is not rapidly increased. Further, the control target value E ₂ (k ₁ ) is calculated according to the power amount Pc.

Specifically, when the rate of change v~(k ₁ ; h) is smaller than the threshold value -β, it is predicted that the power generation amount Pg will sharply decrease in the future. In this case, the output command value E ₁ is reduced by the first power amount before the power generation amount Pg sharply decreases. Since the first power amount is smaller than the reduction rate of the output Ps allowed for the commercial power system 2, the fluctuation (reduction rate) of the power amount Pc of the AC power output from the power conditioner 12 is suppressed. , The power amount Pc can be reduced. Then, by reducing the electric power amount Pc in advance, it is possible to reduce the necessity of sharply reducing the electric power amount Pc when the power generation amount Pg sharply decreases. Therefore, the amount of electric power that should be discharged from the power storage device 16 for smoothing the output Ps of the power generation system 1 can be reduced, so that the capacity of the power storage device 16 can be reduced.

When the rate of change a ₁ (k ₁ ) is larger than the threshold value β, it can be considered that the power generation amount Pg is rapidly increasing. In this case, the output command value E ₁ is increased by the second power amount. This second amount of power is smaller than the rate of increase in the output Ps allowed for the commercial power system 2, so that it is possible to prevent the amount of power Pc from increasing sharply even if the amount of power generation Pg increases sharply. That is, it is possible to increase the power amount Pc while suppressing the fluctuation (rate of increase) of the power amount Pc. As a result, the amount of electric power to be charged in power storage device 16 for smoothing output Ps of power generation system 1 can be reduced, so that the capacity of power storage device 16 can be reduced.

As described above, the sudden increase or decrease of the power generation amount Pg is apparently mitigated, so that the power amount to be charged/discharged by the power storage device 16 for smoothing the output Ps of the power generation system 1 can be reduced. As a result, the output Ps of the power generation system 1 can be smoothed while reducing the capacity of the power storage device 16.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in the above embodiment, the control device 18 and the output smoothing device 20 are divided for convenience, but the control device 18 and the output smoothing device 20 may be configured as the same device. Similarly, in the above embodiment, the control device 19 and the output smoothing device 20 are divided for convenience, but the control device 19 and the output smoothing device 20 may be configured as the same device.

Further, the output smoothing device 20 calculates the output command value E ₁ and the control target value E ₂ , but may calculate only the output command value E ₁ . The calculation of the output command value E ₁ and the control target value E ₂ may be performed by different devices. For example, the controller 18 may calculate the output command value E ₁ and the controller 19 may calculate the control target value E ₂ .

Further, the control device 18 may continuously adjust the output of the power conditioner 12 or may adjust the output of the power conditioner 12 step by step according to the specifications of the power conditioner 12.

Further, the change rate calculation unit 24 is not limited to the least square method, and may calculate the change rate a ₁ (k ₁ ) and the intercept b ₁ (k ₁ ) using a Kalman filter or the like.

Further, the command value calculation unit 25 calculates the output command value E ₁ so as to increase the output of the power conditioner 12 by the second power amount when the change rate a ₁ (k ₁ ) is larger than the threshold β. You may.

Further, in the above-described embodiment, the control device 18 adjusts the conversion efficiency of the power conditioner 12 to make the electric energy Pc smaller than the output command value E ₁ , but the present invention is not limited to this. For example, as shown in FIG. 9, the power generation system 1 may further include a load 40. The load 40 is on the output side of the power conditioner 12 and is connected to the portion L21 of the power line L2. Examples of the load 40 include a hydrogen production device. In this configuration, the control device 18 based on the output command value E _1, by adjusting the power supplied to the load 40, may be smaller than the output command value E ₁ the amount of power Pc. Specifically, the control device 18 transmits a command to the load 40 so that the load 40 consumes the power amount obtained by subtracting the output command value E ₁ from the power amount Pc. As a result, the load 40 consumes the amount of power specified by the control device 18.

1 Power Generation System 11 Renewable Energy Power Generation Device 12 Power Conditioner (Power Converter)
16 power storage device 20 output smoothing device 21 power generation amount acquisition unit 22 measurement data storage unit 23 predicted value acquisition unit 24 change rate calculation unit 25 command value calculation unit 26 power amount acquisition unit 27 measurement data storage unit 28 control target value calculation unit 29 Output unit 30 Power generation amount prediction system 40 Load E ₁ Output command value E ₂ Control target value Pc Power amount Pg Power generation amount Ps output

Claims (5)

Smoothing the output of a power generation system including a renewable energy power generation device, a power conversion device that converts the power generated by the renewable energy power generation device, and a power storage device provided on the output side of the power conversion device. An output smoothing device,
A power generation amount acquisition unit that acquires a first measurement value that is a power generation amount that is the amount of power generated by the renewable energy power generation device;
The first change rate is the change in the amount of power generation rate based on the predicted value of the power generation amount, and different second and the first measurement based rather the power generation amount in the value of the rate of change is a to the first change rate a change rate calculating section for calculating a rate of change,
A command value calculation unit that calculates an output command value for defining an upper limit value of the electric energy of the output power output from the power conversion device based on the first rate of change and the second rate of change;
Equipped with
The command value calculation unit calculates the output command value so as to reduce the power amount of the output power by a first power amount when the first change rate is smaller than a first threshold value, and the second An output smoothing device , which calculates the output command value so as to increase the power amount of the output power by a second power amount when the rate of change is larger than a second threshold value . The change rate calculation unit calculates an approximation function indicating a trend of the first measurement value at a first time, and sets the change rate of the approximation function as the second change rate,
The change rate calculation unit divides a subtraction result obtained by subtracting the value at the first time of the approximation function from the predicted value ahead of the predicted time of the first time by the predicted time, The output smoothing device according to claim 1, wherein the first rate of change is calculated. A power amount acquisition unit that acquires a second measurement value that measures the power amount of the output power;
A control target value calculation unit that calculates a control target value that is a target value of the output of the power generation system,
The output smoothing apparatus according to claim 1 , further comprising: Smoothing the output of a power generation system including a renewable energy power generation device, a power conversion device that converts the power generated by the renewable energy power generation device, and a power storage device provided on the output side of the power conversion device. An output smoothing method executed by an output smoothing device, comprising:
Acquiring a first measurement value obtained by measuring a power generation amount that is a power amount of power generated by the renewable energy power generation device;
The first change rate is the change in the amount of power generation rate based on the predicted value of the power generation amount, and different second and the first measurement based rather the power generation amount in the value of the rate of change is a to the first change rate Calculating the rate of change ,
Calculating an output command value for defining an upper limit value of the electric energy of the output electric power output from the power conversion device, based on the first change rate and the second change rate;
It includes,
In the step of calculating the output command value, when the first change rate is smaller than a first threshold value, the output command value is calculated so as to reduce the power amount of the output power by a first power amount, An output smoothing method , wherein the output command value is calculated so as to increase the power amount of the output power by the second power amount when the second change rate is larger than a second threshold value . In the step of calculating the first rate of change and the second rate of change,
An approximation function indicating a trend of the first measurement value at a first time is calculated, and a rate of change of the approximation function is set to the second rate of change,
The first rate of change is calculated by dividing the subtraction result obtained by subtracting the value at the first time of the approximation function from the predicted value ahead of the predicted time of the first time by the predicted time. The output smoothing method according to claim 4, wherein

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