JP2018007521A - Output smoothing device and output smoothing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an output smoothing device and an output smoothing method which enable the reduction of a capacitance of a power storage device.SOLUTION: An output smoothing device 20 for smoothing an output Ps of a power generation system 1 comprises: a recyclable energy power-generation device 11; a power conditioner 12 operable to convert an electric power generated by the recyclable energy power-generation device 11; and a power storage device 16 provided on an output side of the power conditioner 12. The output smoothing device further comprises: a power generation amount acquisition part 21 operable to acquire a first measurement value as a result of measurement of a power generation amount Pg of an electric power generated the recyclable energy power-generation device 11; a rate-of-change calculation unit 24 operable to calculate a rate of change of the power generation amount Pg based on the first measurement value; and a command value calculation unit 25 operable to calculate an output command value Efor defining an upper limit of an amount of an output power output by the power conditioner 12 based on the rate of change.SELECTED DRAWING: Figure 2

Description

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

  In recent years, construction and grid interconnection of power plants utilizing renewable energy (RE) such as sunlight (PhotoVoltaic: PV) and wind power (Wind Turbine: WT) have become active. However, in power generation using renewable energy, it is difficult for humans to directly control the amount of power generation, and the output can vary greatly because of the influence of the weather. When a renewable energy power plant is connected to a commercial system, it is known that the output fluctuation described above may disrupt the supply and demand balance in the system, which may adversely affect the voltage and frequency in the system. For this reason, a renewable energy power plant connected to a commercial system is required to have a smoothing function of output fluctuation.

  There is known an output smoothing device that sequentially calculates a moving average value of the power generation amount of a renewable energy power generation device and sets a control target value of power at a grid connection point based on the calculated moving average value (for example, 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 to the power storage device, and the power generation amount of the renewable energy power generation device is lower than the control target value. Is smaller, the shortage is discharged from the power storage device.

Japanese Patent No. 4170565

  The amount of power generated by the renewable energy power generation device may fluctuate rapidly depending on the climate and the like. However, in the above-described output smoothing device, the control target value cannot be changed greatly from the viewpoint of output smoothing at the grid connection point. Therefore, 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 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 power generated by the renewable energy power generation device, and a power storage device provided on an output side of the power conversion device. , An output smoothing device that smoothes the output of a power generation system. The output smoothing device includes a power generation amount acquisition unit that acquires a first measurement value obtained by measuring a power generation amount that is the amount of power generated by the renewable energy power generation device, and a power generation amount based on the first measurement value. A change rate calculation unit for calculating a change rate, and a command value calculation unit for calculating an output command value for defining an upper limit value of the amount of output power output from the power converter based on the change rate, Prepare.

  In this output smoothing device, the change rate 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 based on the change rate. An output command value that defines the upper limit value of the amount of power is calculated. Since the tendency of increase / decrease 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 / decrease in the amount of power generation. . For example, if the power generation amount is predicted to decrease sharply, the output command value is calculated so that the power amount of the output power of the power conversion device does not decrease rapidly, and if the power generation amount is increasing rapidly, the power conversion The output command value can be calculated so that the amount of output power of the apparatus does not increase rapidly. As a result, the amount of electric power that the power storage device should 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 a first change rate that is a change rate based on a predicted value of the power generation amount. The command value calculation unit may calculate the output command value so that the power amount of the output power is decreased by the first power amount when the first change rate is smaller than the first threshold. When the first rate of change is smaller than the first threshold value, it is predicted that the power generation amount will decrease rapidly. Therefore, by reducing the output command value by the first power amount before the power generation amount suddenly decreases, the power amount of the output power of the power conversion device is reduced while suppressing fluctuations in the power amount of the output power of the power conversion device. Can be reduced. And by reducing the power amount of the output power of the power converter in advance, it is possible to prevent the power amount of the output power of the power converter from being suddenly reduced when the power generation amount sharply decreases. As a result, the amount of power to be discharged from 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 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 that the power amount of the output power is increased by the second power amount when the second change rate is greater than the second threshold. When the second rate of change is greater than the second threshold, it can be considered that the amount of power generation is increasing rapidly. At this time, by increasing the output command value by the second power amount, the power amount of the output power of the power converter can be prevented from rapidly increasing even if the power generation amount increases rapidly. That is, it is possible to increase the power amount of the output power of the power conversion device while suppressing fluctuations in the power amount of the 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 device described above includes a power amount acquisition unit that acquires a second measurement value obtained by measuring the amount of 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, , May be further provided. In this case, a control target value is calculated according to the amount of output power of the power converter. Thereby, the output of the power generation system can be smoothed 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 an 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. The 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 rate of change in the power generation amount based on the first measurement value. And a step of calculating an output command value for defining an upper limit value of the amount of output power output from the power converter based on the rate of change.

  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 based on the rate of change. An output command value that defines the upper limit value of the amount of power is calculated. Since the tendency of increase / decrease 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 / decrease in the amount of power generation. . For example, if the power generation amount is predicted to decrease sharply, the output command value is calculated so that the power amount of the output power of the power conversion device does not decrease rapidly, and if the power generation amount is increasing rapidly, the power conversion The output command value can be calculated so that the amount of output power of the apparatus does not increase rapidly. As a result, the amount of electric power that the power storage device should 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 illustrating an example of power storage device control executed by the output smoothing device in FIG. 1. It is a figure for demonstrating the smoothing process at the time of the rapid increase in electric power generation amount. It is a figure for demonstrating the smoothing process at the time of sudden reduction of electric power generation amount. It is a figure for demonstrating the smoothing process of the comparative example at the time of sudden reduction of electric power generation amount. It is a figure which shows roughly 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 reference numerals are used for the same or equivalent elements, and redundant descriptions are omitted.

  FIG. 1 is a diagram schematically illustrating 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 a commercial power system 2 and supplies power to a connection point with the commercial power system 2. The power generation system 1 includes a function (hereinafter, simply referred to as “smoothing of the output Ps”) that smoothes fluctuations in the amount of electric power (hereinafter referred to as “output Ps”) at the interconnection point. . The power generation system 1 is, for example, a renewable energy power 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 power using renewable energy. In the renewable energy power generation apparatus 11, the output, that is, the power generation amount Pg can vary. The renewable energy power generator 11 is, for example, a solar power generator or a wind power generator. The renewable energy power generator 11 outputs the generated DC power to the power conditioner 12 through 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 the DC power from the renewable energy power generator 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 wattmeter 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. For example, the wattmeter 13 continuously measures the power generation amount Pg of the renewable energy power generation apparatus 11 in the power line L1. The wattmeter 13 transmits the measured power generation amount Pg to the control device 18 and the output smoothing device 20.

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

  The wattmeter 15 is a device that measures the output Ps. For example, the wattmeter 15 continuously measures the output Ps of the power generation system 1 at a portion L22 between the position where the inverter 17 is connected to the commercial power system 2 in the power line L2. The wattmeter 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 L <b> 2 via the inverter 17. The power storage device 16 is used for smoothing the output Ps of the power generation system 1. Specifically, as the output Ps of the power generation system 1 is a control target value E _2, the power storage device 16 is charged and discharged. Charging / discharging of the power storage device 16 is controlled by the control device 19. Control target value E ₂ is the 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 part of the AC power flowing through power line L <b> 2 into DC power, and outputs the converted DC power to power storage device 16.

Controller 18, a power amount Pc received from the power meter 14, an output command value E ₁ received from the output smoothing device 20, based on the output of the power conditioner 12 (electric power amount Pc of the AC power) It is a device to control. The output command value E ₁ is a value for defining an upper limit value (maximum output) of the output of the power conditioner 12. Controller 18, for example, as the amount of power Pc does not exceed the output command value E _1, controls the output of the power conditioner 12. Specifically, the controller 18, by adjusting the conversion efficiency of the power conditioner 12 is less than the output command value E ₁ the amount of power Pc. For example, the control device 18 adjusts the conversion efficiency of the power conditioner 12 by changing the drive frequency of the power conditioner 12. The control device 18, as to follow the amount of power Pc to the output command value E _1, may control the output of the power conditioner 12.

Control device 19 is a device that controls charging / discharging of power storage device 16 based on output Ps received from wattmeter 15 and control target value E ₂ received from output smoothing device 20. Control device 19, for example, the output Ps is to follow the control target value E _2, to control the charging and discharging of the power storage device 16. As this follow-up control, for example, PID (Proportional-Integral-Derivative) control may be used. More specifically, the control unit 19 subtracts the target control value E ₂ from the output Ps, (if the output Ps is higher than the control target value E ₂₎ that when the subtracted difference is a positive value, the The power storage device 16 is controlled to charge the power storage device 16 with the surplus power that is the difference power. Controller 19, when the difference described above is a negative value (when the output Ps is lower than the control target value E _2), the power storage device power shortage is the power of the difference so as to discharge from the power storage device 16 16 is controlled. In addition, as the power storage device 16 is not repeated charging and discharging, the dead zone of about several% ± is provided for controlling the target value E _2, the control device 19, the power storage device 16 when the output Ps is in the dead zone You may make it not charge / discharge.

The output smoothing device 20 is a device for smoothing the output Ps of the power generation system 1. Output smoothing device 20, so as to smooth the output Ps, and outputs the output command value E ₁ and the control target value E _2. 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 apparatus 11. A known method can 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 has a short time of several tens of minutes to several hours. Specifically, the power generation amount prediction system 30 takes a sky image of the renewable energy power generation apparatus 11 using a camera and analyzes the taken 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 power generation amount by a known method. The power generation amount 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 illustrating 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. A calculation unit 25, an electric energy acquisition unit 26, a measurement data storage unit 27, a control target value calculation unit 28, and an output unit 29 are provided.

  As shown in FIG. 3, the output smoothing device 20 physically includes one or a plurality of processors 201 and a storage device such as a RAM (Random Access Memory) and a ROM (Read Only Memory) which 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. The 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 more predetermined computer programs. In addition, 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 apparatus 11. For example, the power generation amount acquisition unit 21 acquires the power generation amount Pg output from the wattmeter 13 as the measurement value p ₁ at a predetermined sampling interval ΔT ₁ and also acquires the time k ₁ when the measurement value p ₁ is measured. Hereinafter, the measurement value p ₁ at time k ₁ is expressed as 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. Reference time real time t ₁ is 0, may be set to any control execution timing. The sampling interval ΔT ₁ is a control cycle of power conditioner control described later, and is, for example, about 1 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 time k ₁ in association with each other in the measurement data storage unit 22 as first measurement data.

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

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˜ ahead of the predicted time h from the power generation amount 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, about several tens of minutes to one hour. The predicted value acquisition unit 23 outputs the acquired predicted value f˜ (k ₁ + h) to the change rate calculation unit 24.

The change rate calculation unit 24 functions as a change rate calculation unit that calculates the change rate 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 measurement 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 time k ₁ . Specifically, the change rate calculation unit 24 approximates the trend of the measurement value p ₁ (k ₁ ) with a linear function related to time at each time k ₁ (k ₁ = 0, 1, 2,...). The change rate calculation unit 24 calculates an approximate function using, for example, a least square method.

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

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

The change rate calculation unit 24 calculates a change rate v˜ (k ₁ ; h) (first change rate) that is a change rate based on the predicted value f˜ (k ₁ + h) of the power generation amount. The rate of change v˜ (k ₁ ; h) is a predicted value of the rate of change of the average power generation amount Pg between time k ₁ and time k ₁ + h. The change rate calculation unit 24 uses the prediction value f˜ (k ₁ + h) received from the prediction value acquisition unit 23 as shown in the equation (4), and calculates the approximate function from the prediction value f˜ (k ₁ + h). By subtracting the value f (k ₁ ΔT ₁ ; a ₁ (k ₁ ), b ₁ (k ₁ )) and dividing the subtraction result by the time hΔT ₁ , the rate of change v˜ (k ₁ ; h) is obtained. calculate. In general, since the variation of the measured value p ₁ (k ₁ ) is 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 )).

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

Command value calculating section 25, based on the change rate, which functions as a command value calculation means for calculating the output command value E _1. 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.} Note that the threshold value −β (first threshold value) is a threshold value regarding the rate of change v˜ (k ₁ ; h), and is a reduction rate per unit time of the output Ps allowed for the commercial power system 2. The threshold value β (second threshold value) is a threshold value regarding 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. The absolute value may be set to a different value between the threshold relating to the rate of change v˜ (k ₁ ; h) and the threshold relating to the rate of change 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 change rate v˜ (k ₁ ; h) is smaller than the threshold −β, a sudden decrease in the power generation amount Pg exceeding the threshold β is predicted from the time k ₁ until the predicted time h elapses. In this case, the command value calculating unit 25, so as to reduce the output of the power conditioner 12 by a first power amount, calculates the output command value E _1. 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 decreases the output command value E ₁ (k ₁ ) at an allowable change rate. Thereby, the sudden decrease in the apparent power generation amount Pg is alleviated.

When the change rate v ~ (k ₁ ; h) is greater than or equal to the threshold −β and the change rate a ₁ (k ₁ ) is greater than the threshold β, the command value calculation unit 25 calculates the predicted time h from time k _1. Although but the rapid decrease of the power generation amount Pg exceeding a threshold β until elapsed unexpected, rapid increase of the power generation amount Pg exceeds the threshold β is generated at time k _1. In this case, the command value calculating unit 25, as to increase the output of the power conditioner 12 by a second power amount, it calculates the output command value E _1. 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 change rate. Thereby, the sudden increase in the apparent power generation amount Pg is alleviated.

The command value calculation unit 25 calculates the predicted time h from time k ₁ when the rate of change v˜ (k ₁ ; h) is equal to or higher than the threshold −β and the rate of change a ₁ (k ₁ ) is equal to or lower than the threshold β. Until the time elapses, a sudden decrease in the power generation amount Pg exceeding the threshold value β is not predicted, and there is no rapid increase in the power generation amount Pg exceeding the threshold value β at time k ₁ . In this case, the command value calculation unit 25 adds the second electric energy to the output command value E ₁ (k ₁ −1), and outputs the smaller one of the addition result and the output E _max as 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 ) at an allowable change rate within a range of the output E _max or less.

In addition, as shown in Expression (5), priority is given to a case where a 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 subtraction result is set as an 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.

In addition, for the sudden 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 increase in the power generation amount Pg is recognized by the current rate of change a ₁ (k ₁ ). Is possible. On the other hand, for rapid decrease of the power generation amount Pg, output command value _{E 1 (k} 1) Since the reduction in accordance sharp decline in the power generation amount Pg, rapid decrease of the power generation amount Pg by the current change rate _{a 1 (k} 1) is At the recognized stage, 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 AC power output from the power conditioner 12. For example, the power amount acquisition unit 26 acquires the power amount Pc output from the wattmeter 14 as the measurement value p ₂ at a predetermined sampling interval ΔT ₂ and also acquires the time k ₂ when the measurement value p ₂ is measured. Later, it represents the measured value _{p 2} at time _{k 2} and the 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. Reference time as a real-time t ₂ is 0 can be set to any of the 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 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 second measurement data.

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

Control target value calculation portion 28 functions as a control target value calculating means for calculating a control target value E _2. Regarding the calculation control target value E _2, a known method can be used. Here, a method for calculating the control target value E ₂ by approximating the measured value p ₂ (k ₂ ) with a linear function in the same manner as the output command value E ₁ will be described. For example, at each time k ₂ (k ₂ = 0, 1, 2,...), The control target value calculation unit 28 approximates the trend of the measurement value p ₂ (k ₂ ) with a linear function related to time. The control target value calculation unit 28 calculates an approximate function using, for example, a least square method.

Control target value calculation portion 28, as shown in equation (6), the approximate function value of the power quantity Pc at time _{k 2} (smoothed _{value) f (k 2 ΔT 2;} a 2 (k 2), b 2 ( k ₂ )).

Here, the change rate a ₂ (k ₂ ) and the intercept b ₂ (k ₂ ) are obtained by, for example, the least square method, as shown in the equations (7) and (8). Note that the number of data M ₂ used for approximation is determined in advance. Number of data M ₂ is about hundreds to thousands, for example.

The control target value calculation unit 28 uses the approximate function value f (k ₂ ΔT ₂ ; a ₂ (k ₂ ), b ₂ (k ₂ )) as 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 at the same time the control target value E ₂ (k ₂₎ calculated by the control target value calculation unit 28. ) Function as output means for transmitting to the control device 19. 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. When 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 each indicate that the control continuation flag of the power conditioner control indicates the continuation of the power conditioner control. If the control continuation flag indicates the continuation of the power conditioner control, each process may be performed. Each of the electric energy acquisition unit 26, the control target value calculation unit 28, and the output unit 29 determines 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 the power storage device control. In the case where the continuation is indicated, each process may be performed.

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

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 the 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 Is determined (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 associates the acquired measurement value p ₁ (k ₁ ) with the time k ₁ and stores them in the measurement data storage unit 22 as first measurement data (step S13).

Subsequently, the change rate calculation unit 24 determines whether or not the first measurement data having the number of data M ₁ or more is stored in the measurement data storage unit 22 (step S14). In step S14, if the first measurement data of the data number M less than ₁ is determined to be stored in the measurement data storage unit 22 (step S14; No), the determination of step S11 is performed again. On the other hand, when it is determined in step S14 that the first measurement data having the number of data 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 storage. from the first measurement data stored in the section 22, and extracts the latest first measurement data number M ₁ pieces of data as time-series data (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 square method using time series data, as shown in Expression (2). Further, the change rate calculation unit 24 calculates the intercept b ₁ (k ₁ ) by the least square method using time series data, as shown in Expression (3). Then, the change rate calculation unit 24, as shown in Expression (1), approximate function value f (k ₁ ΔT ₁ ; a ₁ (k ₁ ), b ₁ (k ₁ ) of the power generation amount Pg at time k ₁ . ). 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˜ (k ₁ + h) ahead of the predicted time h from the power generation amount prediction system 30 at time k ₁ (step S17). Then, the predicted value acquisition unit 23 outputs the acquired predicted value f˜ (k ₁ + h) to the change rate calculation unit 24.

Subsequently, the change rate calculation unit 24 calculates the change rate v˜ (k ₁ ; h) based on the predicted value f˜ (k ₁ + h) acquired in step S17 (step S18). Specifically, the change rate calculation unit 24 calculates the change rate v˜ (k ₁ ; h) using the predicted values f˜ (k ₁ + h) as shown in the equation (4). 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˜ (k ₁ ; h) calculated in step S18. Is calculated (step S19). Specifically, the command value calculation unit 25 calculates an output command value E ₁ (k ₁ ) as shown in Expression (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 output command value E ₁ (k ₁ ) calculated in step S19 to the control device 18 (step S20), and the determination in step S11 is performed again. In step S11, when it is determined 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 before step S12, and may be performed before each step.

Thus, 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 rate of change v˜ (k ₁ ; h). Thereby, the AC power of the roughly smoothed electric energy Pc is output from the power conditioner 12.

In the power storage device control shown in FIG. 5, first, the electric energy acquisition unit 26 determines whether or not the control continuation flag indicates the continuation of power storage device control (step S31). In step S31, when the control continuation flag is determined to indicate the continuation of the power storage device control (step S31; Yes), the power amount acquisition unit 26, at time k ₂ is an update time of the control target value E ₂ It is determined whether or not it has been 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 obtaining unit 26 stores the measurement data storage unit 27 as the second measurement data in association with the acquired measured value _p 2 and _{(k 2)} and time _{k 2} (step S33).

Subsequently, the control target value calculation unit 28 determines whether or not the second measurement data having the data number M ₂ or more is stored in the measurement data storage unit 27 (step S34). In step S34, if the second measurement data of the data number M less than _two is determined to be 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 number of data M ₂ or more is stored in the measurement data storage unit 27 (step S34; Yes), the control target value calculation unit 28 the second measurement data stored in the storage unit 27, extracts the latest data number M ₂ pieces of second measurement data as time-series data (step S35).

Subsequently, the control target value calculation unit 28 approximates the trend of the measurement value p ₂ (k ₂ ) with a linear function related to time (step S36). Specifically, the control target value calculation unit 28, as shown in Expression (7) and Expression (8), uses the rate of change a ₂ (by the least square method using the time series data extracted in Step S35. k ₂ ) and 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 electric energy Pc at time k ₂ . )).

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 control target value E ₂ (k ₂ ) calculated in step S37 to the control device 19 (step S38), and the determination in step S31 is performed again. In Step S31, when it is determined that the control continuation flag indicates the stop of the power storage device control (Step S31; No), the series of processing of the power storage device control ends. Note that step S31 is not limited to before step S32, and may be performed before each step.

  Thus, in power storage device control, smooth smoothing is performed by power conditioner control, and then smoothing of output Ps is performed by charge / discharge control of power storage device 16.

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

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 the amount of power corresponding to the difference between the output Ps (control target value E ₂ ) and the power generation amount Pg (the region surrounded by the output Ps and the power generation amount Pg in FIG. 8). . Similarly, for a sudden increase in the power generation amount Pg, the power storage device needs to charge the amount of power corresponding to the difference between the output Ps (control target value E ₂ ) and the power generation amount Pg. For this reason, it is necessary to enlarge the capacity | capacitance of an electrical storage apparatus to such an extent that charging / discharging is possible, and the cost of an electrical storage apparatus increases.

  On the other hand, as shown in FIG. 6, in the output smoothing device 20, the power amount Pc of AC power output from the power conditioner 12 is sequentially suppressed when the power generation amount Pg increases rapidly. This apparently mitigates the sudden increase in the amount of power Pc. As shown in FIG. 7, in the output smoothing device 20, when the power generation amount Pg is suddenly reduced, the power amount Pc of the AC power output from the power conditioner 12 when the sudden decrease in the power generation amount Pg is predicted is obtained. Pre-suppressed. As a result, the sudden decrease in the amount of electric power Pc is moderated.

Thus, 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 rapid increase or rapid decrease of the power generation amount Pg. Thereby, the fluctuation | variation of the electric power generation amount Pg is smoothed to some extent, and the electric energy Pc is obtained. Then, with respect to the variation of the amount of power Pc due to instantaneous spikes and sharp decrease etc. not be predicted power generation amount Pg, the difference between the control target value E ₂ and the amount of power Pc is the charging and discharging of the power storage device 16 By supplementing, the output Ps is smoothed. For this reason, compared with the comparative example shown in FIG. 8, the capacity of the power storage device 16 can be reduced, and the construction cost of the 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 the time k ₁ based on the measured value p ₁ (k ₁ ) obtained by measuring 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), an output command value E ₁ (k ₁ ) that defines the upper limit value of the amount of electric power Pc of the AC power output from the power conditioner 12 is calculated. Since the change rate a ₁ (k ₁ ) and the change rate v˜ (k ₁ ; h) can grasp the trend of increase / decrease in the power generation amount Pg, according to the trend of increase / decrease in the power generation amount Pg. 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 the power generation amount Pg is predicted to decrease rapidly, 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 rapidly decreased, and the power generation amount Pg Is increased, the output command value E ₁ (k ₁ ) is calculated so as not to increase the power amount Pc rapidly. Further, a control target value E ₂ (k ₁ ) is calculated according to the electric energy Pc.

Specifically, when the rate of change v˜ (k ₁ ; h) is smaller than the threshold −β, it is predicted that the power generation amount Pg will rapidly decrease in the future. In this case, before the power generation amount Pg decreases rapidly, reducing the output command value E ₁ by a first amount of power. Since the first electric energy is smaller than the reduction rate of the output Ps allowed for the commercial power system 2, the fluctuation (decrease rate) of the electric energy Pc of the AC power output from the power conditioner 12 is suppressed. The electric energy Pc can be reduced. Then, by reducing the power amount Pc in advance, it is possible to reduce the necessity of suddenly reducing the power amount Pc when the power generation amount Pg decreases rapidly. For this reason, since the electric energy which should be discharged from the electrical storage apparatus 16 for smoothing the output Ps of the electric power generation system 1 can be reduced, it becomes possible to reduce the capacity | capacitance of the electrical storage apparatus 16. FIG.

When the change rate 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, increasing the output command value E ₁ by the second power amount. Since the second power amount is smaller than the increase rate of the output Ps allowed for the commercial power system 2, even if the power generation amount Pg increases rapidly, the power amount Pc can be prevented from increasing rapidly. That is, the power amount Pc can be increased while suppressing the fluctuation (increase rate) of the power amount Pc. Thereby, the amount of power to be charged in 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.

  As described above, since the sudden increase or sudden decrease in the power generation amount Pg is apparently mitigated, it is possible to reduce the amount of power that the power storage device 16 should charge / discharge for smoothing the output Ps of the power generation system 1. As a result, it is possible to smooth the output Ps of the power generation system 1 while reducing the capacity of the power storage device 16.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said 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 is performed a calculation of the output command value E ₁ and the control target value E _2, may be performed by the calculated output command value E _1. Calculation of the output command value E ₁ and the control target value E ₂ may be performed by different devices. For example, controller 18 may perform the calculation of the output command value E _1, the control unit 19 may perform the calculation of the control target value E _2.

  Moreover, the control apparatus 18 may adjust the output of the power conditioner 12 continuously according to the specification etc. of the power conditioner 12, and may adjust it in steps.

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 that the output of the power conditioner 12 is increased by the second power amount when the change rate a ₁ (k ₁ ) is larger than the threshold value β. May be.

In the above embodiment, the control device 18, the power by adjusting the conversion efficiency of the conditioner 12, although smaller than the output command value E ₁ the amount of power Pc, not limited to this. For example, as illustrated 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 apparatus. 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 controller 18 sends a command to power amount obtained by subtracting the output command value E ₁ from the power amount Pc to the load 40 so as to consume the load 40. As a result, the load 40 consumes the amount of power specified by the control device 18.

DESCRIPTION OF SYMBOLS 1 Power generation system 11 Renewable energy power generation device 12 Power conditioner (power conversion device)
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 comprising a renewable energy power generation device, a power conversion device that converts power generated by the renewable energy power generation device, and a power storage device provided on an output side of the power conversion device An output smoothing device comprising:
A power generation amount acquisition unit that acquires a first measurement value obtained by measuring a power generation amount that is the amount of power generated by the renewable energy power generation device;
Based on the first measurement value, a change rate calculation unit that calculates a change rate of the power generation amount,
A command value calculation unit that calculates an output command value for defining an upper limit value of the amount of output power output from the power converter based on the rate of change;
An output smoothing device comprising: The change rate calculation unit calculates a first change rate that is a change rate based on a predicted value of the power generation amount,
The said command value calculation part calculates the said output command value so that the electric energy of the said output electric power may be decreased only by the 1st electric energy when the said 1st change rate is smaller than a 1st threshold value. The output smoothing apparatus described in 1. The change rate calculation unit calculates a second change rate that is a change rate based on the first measurement value,
The said command value calculation part calculates the said output command value so that the electric energy of the said output electric power may be increased only by 2nd electric energy, when the said 2nd change rate is larger than a 2nd threshold value. The output smoothing apparatus described in 1. An electric energy acquisition unit for acquiring a second measurement value obtained by measuring the electric energy 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 device according to any one of claims 1 to 3, further comprising: Smoothing the output of a power generation system comprising a renewable energy power generation device, a power conversion device that converts power generated by the renewable energy power generation device, and a power storage device provided on an output side of the power conversion device An output smoothing method executed by the output smoothing device,
Obtaining a first measurement value obtained by measuring a power generation amount that is an amount of power generated by the renewable energy power generation device;
Calculating a rate of change of the power generation amount based on the first measurement value;
Calculating an output command value for defining an upper limit value of the amount of output power output from the power converter based on the rate of change;
An output smoothing method including:

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