Patent Application
20220224120
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2021-003044, filed on Jan. 12, 2021 the entire contents of which are incorporated herein by reference.
The embodiments of the present invention relate to a power control device and a power control method.
A hydrogen generation system that produces hydrogen by using a power supplied from a power system and a power of a renewable energy generation device in which the fluctuation of the generated power is larger than that of the electric power system is generally known. In such a hydrogen system, an amount of hydrogen which satisfies a hydrogen demand is produced while adjusting a supply-demand balance of the power supplied from the power system.
On the other hand, in adjusting the supply-demand balance, the energy management system predicts the generated power of renewable energy based on information such as weather, and declares in advance a power sale (or purchase) in a certain time period. Then, in a declared time period, it is necessary to control each device to match a declared plan with an actual amount of power sale [kWh] (or amount of power purchase [kWh]). Generally, the balance of supply and demand is adjusted every 30 minutes, and the amount of power [kWh] per 30 minutes(=integrated value of instantaneous power) may be matched. However, the control response of the hydrogen production device is generally slower than the fluctuation of the renewable energy generation device.
In addition, until now, power plants (thermal power plants, etc.) have generally adjusted the supply-demand balance. However, in recent years, the spread of renewable energy has been increasing, and it is desirable to adjust the supply-demand balance by using renewable energy in the future.
Hereinafter, the power control device and the power control method according to the embodiment of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are only examples of the embodiments of the present invention and the present invention is not limited to the embodiments. In the drawings referred to in the embodiments, same parts or parts having identical functions are denoted by like or similar reference characters and there is a case where redundant explanations thereof are omitted. Further, for convenience of explanation, there are cases where dimensional ratios of the parts in the drawings are different from those of actual products and some part of configurations is omitted from the drawings.
A power control device for a hydrogen system according to the present embodiment is a power control device configured to control a supply of generated power generated by a renewable energy generation device, and includes an acquirer and a controller. The acquirer acquires information related to an amount of power sale in a predetermined period. The controller controls the power supplier of the renewable energy generation device to sell power from the generated power, such that the integrated value of the power sale in time series in a predetermined period becomes the power sale amount. The controller makes an average value of the power sale in a first period within the predetermined period larger than the average value of a second period within the predetermined period after the first period. According to this embodiment, it is possible to suppress the deviation between a planned value and an actual value of the amount of power sale.
In the present embodiment, changing the power consumption pattern of the hydrogen production plant 10 according to the power supply status is referred to as demand response (hereinafter, may be simply referred to as DR). There are two types of demand response: so-called “fall DR” as “demand reduction” and so-called “raise DR” as “demand increase”. In the so-called “fall DR”, at least one of suppressing the power consumption of the hydrogen production plant 10 and increasing the power production is performed. When the amount of electric power production increases, the electric power generated by the hydrogen production plant 10 may be sold.
In the so-called “upward DR”, at least one of increasing the power consumption of the hydrogen production plant 10 and suppressing the power production is performed. This makes it possible to effectively cut the peak of the power system Eps in the “downward DR”. In the “upward DR”, it is possible to stabilize the quality of electricity such as voltage and frequency by encouraging consumers to increase the consumption of electric power when the electric power supply becomes excessive.
The hydrogen production plant 10 may sell the surplus power from the generated power pv (t) generated by the renewable energy generation device in the hydrogen production plant 10 as the instantaneous power salex (t). In other words, the instantaneous power salex (t) is reverse-powered to the power system Eps to sell the power. Here, t indicates time. Note that, in this embodiment, the instantaneous power salex (t) according to the present embodiment corresponds to the power sale.
Further, the hydrogen production plant 10 produces hydrogen from the generated power pv (t) generated by the renewable energy generation device and the power supplied from the power system Eps. The hydrogen production plant 10 outputs a measurement signal including information about the generated power pv (t) and the instantaneous power salex (t) to the power control device 30.
The energy management system 20 outputs a command signal including information about a planned value of power sale sv within a predetermined period to the power control device 30. Further, the predetermined time interval in which the planned value of power sale sv is set corresponds to the demand response period. In the demand response period, the planned value of power sale sv may be set by an agreement with an electric power company.
Therefore, if the amount of power sale does not reach the planned value of power sale sv during the demand response period a penalty may be imposed depending on the contract for the amount of power sale which does not reach the planned value of power sale sv. The demand response period may be in units of 30 minutes, and the period may be 30 to 120 minutes. As such, the energy management system 20 is a system for creating an operation plan for the hydrogen production plant 10. The operation plan is generally a 48-division operation plan in which a day is divided into 30-minute units.
The power control device 30 is a control device that controls the hydrogen production plant 10 based on the operation plan created by the energy management system 20. More specifically, the power control device 30, based on a measurement signal including information about the generated power pv (t) and the instantaneous power salex (t) supplied from the hydrogen production plant 10 and a command signal including information on the planned value of power sale sv, outputs a command signal including information about a input power instruction value u (t) and an output power of a power conditioner p (t) to the hydrogen production plant 10. The power system Eps may be a transmission and distribution network managed by a power company.
The renewable energy generation device 10a has a generation facility derived from natural energy. The generation facility derived from this renewable energy may be a photovoltaic power generation device (PV) using sunlight, and generates the generated power pv (t). For example, the renewable energy generation device 10a according to the present embodiment, branches the generated power pv (t) to a power sale side and the hydrogen production device 10c, and the power supplier of the renewable energy generation device 10a converts DC to AC. As described above, the renewable energy generation device 10a outputs a measurement signal including information about generated power pv (t), which is AC power values of generated power, and instantaneous power salex (t) to the power control device 30. Note that, in the present embodiment, the power generated by the renewable energy generation device 10a may be referred to as PV generated power.
The renewable energy generation device 10a does not require fuel such as fossil fuel, but its generation amount is unstable because it is affected by environment such as weather. The renewable energy generation device 10a may be a wind power generation facility or a generation facility using new energy such as biomass or biomass-derived waste. The hydrogen production plant 10 according to the present embodiment includes, but is not limited to, a renewable energy generation device in the hydrogen production plant 10. For example, the hydrogen production plant 10 may be configured without the renewable energy generation device 10a. In this case, the power control device 30 may respectively control the hydrogen production plant 10 and the renewable energy generation device 10a.
The power conditioner 10b may be configured to include a converter. This converter converts the generated power pv (t) output by the renewable energy generation device 10a into a predetermined output power p (t). More specifically, the power conditioner 10b supplies the output power p (t) which is adjusted in magnitude from the generated power pv (t) to the hydrogen production device 10c, according to the command signal including the information about the output power p (t) input from the power control device 30. In other words, the magnitude of the output power p (t) output by the power conditioner 10b is adjusted to be equal or less than the generated power pv (t). Note that, in the present embodiment, the DC power is branched from the power sale side and the hydrogen production device 10c, and the power supplier included in the renewable energy generation device 10a is configured to perform DC-AC conversion, but the present invention is not limited to this. For example, the power conditioner 10b may be configured to be included in the renewable energy generation device 10a. In this case, the power supply from the power conditioner 10b may be configured and controlled so as to be branched and supplied to the power sale side and the hydrogen production device 10c side. In such configuration, the power conditioner 10b included in the renewable energy generation device 10a corresponds to the power supplier.
The hydrogen production device 10c produces hydrogen from electricity and water by electrolysis of water. The hydrogen production device 10c may be an electrowater decomposition device that produces hydrogen and oxygen by passing an electric current through an alkaline solution. Further, the hydrogen production device 10c stores the generated amount of hydrogen H (t) in the hydrogen storage device 10d via a hydrogen pipe. Further, the hydrogen production device 10c outputs a measurement signal including information about the amount of hydrogen production h (t) to the power control device 30.
The hydrogen production device 10c produces the amount of hydrogen H (t) corresponding to the input power instruction value u (t) according to a command signal including information about the input power instruction value u (t) input from the power control device 30. Since power is generally not supplied from the power system Eps when the surplus power of the generated power pv (t) is sold, the value of the output power p (t) output from the power conditioner 10b and the input power instruction value u (t) are equivalent. Therefore, in the following, the input power instruction value u (t) will be described as a control example at the time of power sale. Note that, in the present embodiment, the input power instruction value u (t) will be described as a control example at the time of power sale, but the present invention is not limited to this. For example, the output power p (t) may be controlled in the same manner as the input power instruction value u (t).
The hydrogen storage device 10d stores hydrogen produced by the hydrogen production device 10c. The hydrogen storage device 10d is connected to the hydrogen production device 10c and the hydrogen load HR via a pipe. Further, the hydrogen storage device 10d supplies hydrogen to the hydrogen load HR via the pipe. Note that the renewable energy generation device 10a and the power conditioner 10b may be arranged outside the hydrogen production plant 10. In other words, the hydrogen production plant 10 may be configured to not include the renewable energy generation device 10a and the power conditioner 10b.
The hydrogen load HR may be a fuel cell generator, a fuel cell vehicle, or the like. Alternatively, the hydrogen load HR may be a trailer for delivering hydrogen to each consumer.
The memory 30a may be realized by a RAM (Random Access Memory), a semiconductor memory element such as a flash memory, a hard disk, or the like. The memory 30a stores programs executed by the controller 30c, various control data, and control parameters. The setting parameters used by the real-time target value generator 302, which will be described later, may be stored.
The interface 30b communicates with the renewable energy generation device 10a (
Further, the interface 30b may receive command signal including information such as a prediction value of PV generated power amount Prep, plant power consumption (=minimum), and PV generated amount confidence interval for each time section of control from the energy management system 20 (
The controller 30c may be configured to include a CPU (Central Processing Unit), and executes control based on a program stored in the memory 30a. The controller 30c includes an integrated target value generator 300, a real-time target value generator 302, a command value calculator 304, and a command value outputter 306. Note that the integrated target value generator 300, the real-time target value generator 302, the command value calculator 304, and the value outputter 306 may each be configured by a circuit. Further, in the present embodiment, the start time in the time section of control such as the demand response period is referred to as a frame start time, and the end time is referred to as a frame end time. Further, the unit time of the demand response period is referred to as a frame. The real-time target value generator 302 according to the present embodiment corresponds to the target value generator, and the real-time target value sv (t) which will be described later corresponds to the target value.
The integrated target value generator 300 generates the integrated target value sv_I of the current frame by using the planned value of power sale sv acquired from the energy management system 20. In the demand response, the controller 30c controls the hydrogen production plant 30 such that the integrated target value sv_I matches the integrated value of the instantaneous power sale x (t). The integrated target value sv_I according to the present embodiment corresponds to the amount of power sale within a predetermined period.
The integrated target value generator 300 may generate an integrated target value sv_I of the current frame according to an equation (1), based on the planned value of power sale sv. Since this integrated target value sv_I is an invariant value in the frame, it is calculated at the start of the frame.
The real-time target value generator 302 uses the setting parameters stored in the memory 30a and the integrated target value sv_I generated by the integrated target value generator 300, to generate a real-time target value sv (t) of instantaneous power sale x (t) which is a control target in a control cycle such as a second or minute. A detailed control example of the real-time target value generator 302 will be described later.
The command value calculator 304 calculates the input power instruction value u (t) of the hydrogen production device 10c using the real-time target value sv (t) generated by the real-time target value generator 302 as the control target in each control cycle. Then, the command value outputter 306 outputs the input power instruction value u (t) to the hydrogen production device 10c.
More specifically, the command value calculator 304 controls the input power with PID control such that the real-time target value sv (t) and the instantaneous power sale x (t) match according to an equation (2) and an equation (3). KP, KI, and KD respectively are control parameters of the PID controller.
As illustrated in
On the other hand,
In this way, when the real-time target value sv (t) of the instantaneous power sale x (t) is set to be constant for 30 minutes because the PV generated power 30 minutes ahead is unknown, hydrogen can be produced in excess and the instantaneous power sale may be matched with the target value if a surplus of PV is generated in a former half of a 30-minute frame, but the instantaneous power sale decreases and cannot match with the target value if the PV generated power decreases in the latter half of the 30-minute frame.
Therefore, the real-time target value generator 302 according to the present embodiment does not make the real-time target value sv (t) constant, but generates the real-time target value sv (t) which changes according to situation. As such, the integrated target value sv_I (see equation (1)) and the actual value, which is the integrated value for one frame of the instantaneous power sale x (t), are controlled to match.
For example, assuming that when the real-time target value sv (t) is a slope of A=−0.5 (kW/s); at the start of the frame (T_COUNT=0), sv (t)=10450 kW; 15 minutes later (T_COUNT=900), sv (t)=10000 kW; and at the end of the frame (T_COUNT=1800), sv (t)=9550 kW is obtained. In this way, it is possible to increase the integrated value of the instantaneous power sale x (t) in the former half by increasing the instantaneous power sale x (t) in the former half of the 30-minute frame. That is, an average value of the instantaneous power sale x (t) in the first period (former half) in one frame within a predetermined period is made larger than the average value in the second period (latter half) in one frame after the first period. As a result, even when the PV generated power pv (t) decreases in the latter half, the integrated value of the instantaneous power sale x (t) for one frame may be made to match the integrated target value sv_I. In other words, even when the generated power pv (t) decreases in the second period, it is possible to compensate in advance for the decrease in the instantaneous power sale x (t) in the second period by the instantaneous power sale x (t) in the first period. Therefore, it is possible to reduce the possibility that the integrated target value sv_I for 30 minutes and the actual value, which is the integrated value for one frame of the instantaneous power sale x (t), deviate from each other.
Further, the real-time target value generator 302 may change the slope of the straight line according to the prediction accuracy of the prediction value of PV generated power amount Prep according to the prediction accuracy of the predicted value. In other words, the slope A is reduced as the standard deviation σ, as the information about the prediction accuracy becomes smaller.
Further, it may be possible to acquire the prediction of the prediction value of PV generated power amount Prep from the energy management system 20 before the demand response agreement. In such case, as the prediction accuracy of the prediction value of PV generated power amount Prep decreases, as the planned value of power sale sv represented by the formula (1) may be reduced according to an agreement with an electric power company or the like, the integrated target value sv_I may be lowered. In other words, the planned value of power sales sv (see
Furthermore, if the prediction of the prediction value of PV generated power amount Prep can be acquired before the demand response agreement, the integrated target value sv_I may be decreased and the slope A may be increased, as the prediction accuracy decreases. As a result, it becomes possible to increase the integrated value of the instantaneous power sale x (t) in the earlier period, and it is possible to further reduce the possibility that the integrated target value sv_I for 30 minutes and the actual value, which is the integrated value for one frame of the instantaneous power sale x (t), deviate from each other.
The memory 30a may store the slope A in the equation (4) in advance for each time period. The prediction accuracy of the prediction value of PV generated power amount Prep for each time period of the day may have periodicity for each time period. Therefore, the real-time target value generator 302 may set the slope A in the equation (4), even when the prediction accuracy of the prediction value of PV generated power amount Prep is unknown.
In this way, the threshold value TIME_LIMIT of the elapsed time in one frame within a predetermined period and the ratio α are determined in advance, and the real-time target value generator 302 changes the time-series real-time target value sv (t) according to the ratio α before and after the threshold value TIME_LIMIT according to the elapsed time in one frame.
As illustrated in
In the control example according to equation (5), the ratio α may be increased as the prediction accuracy of the prediction value of PV generated power amount Prep decreases. By lowering the integrated target value sv_I and increasing the ratio α, it is possible to increase the integrated value of the instantaneous power sale x (t) in the period before the threshold value TIME_LIMIT, and it is possible to further reduce the possibility that the integrated target value sv_I for 30 minutes and the actual value, which is the integrated value for one frame of the instantaneous power sale x (t), deviate from each other.
The memory 30a stores each coefficient of the equations (1) to (5) as parameters. Then, the real-time target value generator 302 generates the real-time target value sv (t) according to each parameter stored in the memory 30a.
Further, in the present embodiment, the instantaneous power sale x(t) is controlled by the input power command value u (t) to the hydrogen production device 10c, but the present invention is not limited to this. As described above, the output command value to the power conditioner 10b which can suppress the output of the generated power pv (t) may be controlled. Alternatively, when there is a control command value capable of adjusting the instantaneous power sale x (t), the control command value may be output by a similar control. Furthermore, in the present embodiment, the input power command value u (t) is used for controlling the hydrogen production apparatus 10c, but the present invention is not limited to this. The power according to the input power command value u (t) may be supplied to a storage battery or the like.
First, the interface 30b acquires the planned value of power sale sv (step S100). Subsequently, the interface 30b supplies the planned value of power sale sv to the integrated target value generator 300.
Next, the interface 30b acquires the generated power pv (t) from the hydrogen production plant 10 (step S102). Subsequently, the integrated target value generator 300 generates the integrated target value sv_I based on the planned value of power sale sv (step S104).
Next, the real-time target value generator 302 generates each parameter for generating the real-time target value sv (t) and stores it in the memory 30a (step S106).
Next, the real-time target value generator 302 determines whether the demand response frame has started, according to the input information from the energy management system 20 (step S108). When it is determined that the demand response frame has started (YES in step S108), the real-time target value generator 302 generates the real-time target value sv (t) (step S110). On the other hand, when it is determined that the demand response frame has not started (NO in step S108), the real-time target value generator 302 does not generate the real-time target value sv (t).
Next, when the real-time target value sv (t) exists, the command value calculator 304 calculates the input power command value u (t) by PID control using the real-time target value sv (t) (step S112). On the other hand, when the real-time target value sv (t) is not generated, the input power command value u (t) according to the normal operation plan value is generated (step S114).
The command value outputter 306 outputs the input power command value u (t) to the hydrogen production device 10c (step S116). Next, the controller 30c determines whether or not to terminate the entire process (step S116). If it is determined to not end the entire process (NO in step S116), the process from step S100 is repeated. On the other hand, when it is determined to terminate the whole process (YES in step S116), the whole process is finished.
As described above, according to the present embodiment, the controller 30c controls such that the average value of the instantaneous power sale x (t) in the first period in one frame within the predetermined period is larger than the average value in the second period in one frame after the first period. As a result, even when the generated power pv (t) decreases in the second period, the decrease in the instantaneous power sale x (t) in the second period can be compensated in advance by the instantaneous power sale power x (t) in the first period. Therefore, it is possible to reduce the possibility that the integrated target value sv_I (see equation (1)) for 30 minutes and the actual value, which is the integrated value for one frame of the instantaneous power sale x (t), deviate from each other.
The power control device 30 according to a second embodiment is different from the power control device 30 according to the first embodiment, in which the generated power may be predicted in a short term. Hereinafter, the differences from the power control device 30 according to the first embodiment will be described.
The predictor 308 makes a short-term prediction of the renewable energy generation device 10a. The predictor 308 may generate the predicted generated power value y (t) of the renewable energy generation device 10a for one frame of the demand response period.
More specifically, the predictor 308 may generate the predicted generated power value y (t) by using an ARMA model (autoregressive moving average model) which is a type of time series analysis method. The ARMA model is a combination of an AR model (autoregressive model) and an MA model (moving average model), and may be expressed by equation (6).
Here, y (t) is the predicted generated power of the renewable energy generation device 10a at time t; c, φ1˜φp, and θ1˜θq are parameters; and ε (t) is a white noise at time t. p represents the order of the AR model, and q represents the order of the MA model. The predictor 308 determines various parameters and two orders of equation (6) using the past data of the PV generated power stored in the database in advance before the actual estimation, and stores them in the memory 30a.
As shown in
By multiplying the ratio of the average value ypre_mean of the predicted generated power value y (t) up to 30 minutes ahead and the integrated target value sv_I with respect to the predicted generated power value y (t) at time t, the integrated real-time target value which is generated matches the integrated target value.
In this way, the same effect as that of the first embodiment may be obtained. Further, by performing a time series prediction of the predicted generated power value y (t) using past data, it is possible to generate a real-time target value sv (t) according to the fluctuation of the generated power pv (t), and it is possible to further improve a control performance of matching an actual amount of power sale for 30 minutes with the target value of the demand response.
Note that, in this embodiment, the ARMA model of the time series analysis method is used, but the present invention is not limited to this. The AR model, the MA model, an ARIMA model, a SARIMA model, or the like may be used as the prediction model. Alternatively, a prediction method for deep learning such as a neural network or LSTM may be used as the prediction model. In neural networks and deep learning, various types of data may be used as input data. For example, it is possible to further improve the prediction accuracy by inputting various data related to PV generated power such as an amount of solar radiation, temperature, wind speed, and time. Further, as shown in
Further, as described above, the energy management system 20 may add data such as a deviation value and a degree of confidence as an index of prediction accuracy to the prediction value of PV generated power amount Prep. This information may be available from the energy management system 20. In such case, as the prediction accuracy of the prediction value of PV generated power amount Prep decreases, for example, by an agreement with the electric power company or the like, the planned amount of power sale sv represented by the equation (1) may be reduced, and the integrated target value sv_I may be lowered. As a result, the deviation between the integrated target value sv_I and the actual value may be suppressed.
Further, as described above, as the prediction accuracy of the prediction value of PV generated power amount Prep decreases and the integrated target value sv_I is lowered, the real-time target value sv (t) in the former half may be generated so as to take a larger value than the real-time target value sv (t) in the second half. As a result, the deviation between the integrated target value sv_I and the actual value may be further suppressed.
Further, in the present embodiment, the predictor 308 predicts the generated power value y (t) of the renewable energy generation device 10a, but the present invention is not limited to this. The prediction target may be data related to the generated power of the renewable energy generation device 10a such as the amount of solar radiation. When predicting the amount of solar radiation, the generated power of the renewable energy generation device 10a may be calculated from the predicted amount of solar radiation by calculation using a physical formula. Alternatively, the relationship between the amount of solar radiation and the generated power of the renewable energy generation device 10a may be stored by a statistical method, and the generated power of the renewable energy generation device 10a may be calculated from the predicted amount of solar radiation.
In the present embodiment, a short-term prediction of the generated power value y (t) up to 30 minutes ahead was performed to generate the real-time target value sv (t) at the start of the frame, but the real-time target value sv (t) may be generated each time by re-predicting every minute. However, even when the generated power value y (t) is re-predicted every minute, it is necessary to match the integrated value of the real-time target value sv (t) with the integrated target value.
For example, when the real-time target value sv (t) is generated 5 minutes after the start of the frame, it is necessary to generate the real-time target value sv (t) from 5 to 30 minutes, considering the real-time target value for 5 minutes from the start of the frame. Therefore, the real-time target value generator 302 may generate the real-time target value sv (t) according to an equation (8) to an equation (10).
More specifically, because 5 minutes have passed from the start of the frame, the average value (tmp_kW_mean) of the generated real-time target values from the current time t to the end of the frame is calculated using the real-time target value sv (t) during that period. Next, the average value (tpp_ypre_mean) of the predicted generated power value y (t) from the current time t to the end of the frame is calculated. Then, by multiplying the predicted generated power value y (t) by the ratio of the average value of the real-time target value sv (t) from the present time to the end of the frame and the average value of the predicted generated power value y (t), the integrated value of the generated real-time target value sv (t) matches the integrated target value sv_I. In the following formula, k represents the time at the start of the frame.
By re-predicting the generated power pv (t) not only at the start of the frame but also during the frame, it is possible to respond even when the generated power pv (t) suddenly fluctuates and the prediction error becomes large. In the above, the real-time target value is generated by re-predicting the generated power pv (t) when an update cycle such as every minute is reached, but the memory may store the threshold value related to the error of predicted generated power value y (t), and generate the real-time target value sv (t) by re-predicting the generated power pv (t) when the error of the predicted generated power value y (t) exceeds the threshold value.
Note that, in the present embodiment, the prediction value of PV generated power amount in units of 30 minutes is acquired from the energy management system 20 in the interface 30b, but the present invention is not limited to this. The amount of PV generated power in 30-minute units may be predicted in the power control device 30 of the hydrogen production plant 10. Alternatively, the PV generated power amount in units of 30 minutes may be acquired from another device via the Internet.
When the real-time target value generation unit 302 determines that the demand response frame has started (YES in step S108), the real-time target value generation unit 302 determines whether it has reached the PV generated power prediction update cycle (step S118). When determining that the predicted update cycle is reached (YES in step S118), the real-time target value generation unit 302 generates the real-time target value sv (t) based on the predicted generated power value y (t) (step S118). As such, in the prediction update cycle, the real-time target value generator 302 generates the real-time target value sv (t) based on the predicted generated power value y (t).
As described above, according to the present embodiment, the generated power y (t) of the renewable energy generation device 10a is predicted in the predictor 308. This makes it possible to generate the real-time target value sv (t) according to fluctuations in the generated power pv (t), and further improve the control performance which matches the actual amount of power sale for 30 minutes with the target value of the demand response.
While certain embodiments have been described above, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel devices, methods, and programs described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the forms of devices, methods, and programs described herein may be made without departing from the spirit of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-003044 | Jan 2021 | JP | national |
