JP2016226238A - Renewable energy output system, renewable energy output fluctuation suppression method and renewable energy output fluctuation suppression program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable power supply to an external power system by suppressing output fluctuation in a renewable energy output system.SOLUTION: The renewable energy output system which includes a renewable energy power generation facility and a variable power utilization device and is capable of supplying surplus output to the external power system comprises: a control part which acquires generation power information by the renewable energy power generation facility and controls a power supply amount to be consumed by the variable power utilization device in the generation power. The control device uses output Pf that is obtained by smoothing time-series output P of the renewable energy power generation facility with a predetermined time constant and a predetermined function F defining Pf as a parameter to calculate power consumption Pe of the variable power utilization device from a formula of Pe=P-[Pf-F(Pf)](a maximum value of F(Pf)=upper limit power consumption of the variable power utilization device), and performs control for supplying the calculated power consumption to the variable power utilization device and supplying the surplus output to the external power system.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an output fluctuation system of a power plant using renewable energy and its fluctuation suppression.

Development of technology that generates electricity using renewable energy using wind power or sunlight and uses the power is being promoted along with its practical application. Renewable energy is subject to fluctuations in output depending on natural conditions such as wind and weather. For this reason, in areas where there is little adjustment capacity of the power system, the amount of wind power generation introduced may be limited to maintain the frequency.
As the above countermeasure, for example, a renewable energy output system has been proposed in which part of the generated power is consumed by a variable power utilization device and surplus power is supplied to an external electrode system.

Specifically, Patent Document 1 proposes a technique for compensating for the deviation of the wind power generator output with respect to the averaged output by charging / discharging from the power storage device and suppressing the output fluctuation, and surplus power. Is used for the electrolysis of water to obtain hydrogen and oxygen.
Patent Document 2 proposes a method of limiting output when the output of a wind power generator exceeds the range that can be compensated for by the power storage device. Thereby, it is said that the scale of the inverter and the power storage device can be reduced as compared with Patent Document 1, and it is easily established economically. Fluctuations in wind power generation output are introduced into water electrolyzers to supply the remaining stable power to the power system.

JP 62-20889 A JP 2006-161123 A

  However, in a system in which a fluctuation component of the renewable energy output is supplied to a variable power utilization device such as water electrolysis and a constant output is transmitted to the power system, not only normal fluctuations but also wind or the like as shown in FIG. In some cases, the natural energy input suddenly weakens and the power generation output decreases sharply. In such a case, even if the power consumption of the variable power utilization apparatus is reduced to 0, it is impossible to maintain a constant output power transmission, resulting in a sudden fluctuation in the power transmission output. In order to solve this problem, a proposal to install a storage battery or the like has been made, but there is a drawback of raising the total equipment cost. Further, in the conventional system, since the power fluctuation of the variable power utilization apparatus is severe, there is a demerit that the equipment utilization rate is lowered and the economic efficiency is deteriorated.

  The present invention has been made against the background of the above circumstances, and can be supplied while suppressing fluctuations in the power supplied to the external electrode system even when there is a sudden fluctuation in the renewable energy output. It is an object of the present invention to provide a renewable energy output system, a renewable energy output fluctuation suppression method, and a renewable energy output fluctuation suppression program that can be operated in a systematic manner.

That is, the first form of the renewable energy output system of the present invention is:
In a renewable energy output system having a renewable energy power generation facility and a variable power utilization device and capable of supplying surplus output to an external power system,
Obtaining generated power information by the renewable energy power generation facility, comprising a control unit for controlling the power supply amount consumed by the variable power utilization device among the generated power,
The control unit uses an output Pf obtained by smoothing the time series output P of the renewable energy power generation facility with a predetermined time constant, and a predetermined function F using Pf as a variable, and Pe = P− [Pf−F ( Pf)] (where F (Pf) is the maximum value = the upper limit power consumption of the variable power utilization device), the power consumption Pe of the variable power utilization device is calculated, and the calculated power consumption is the renewable energy power generation facility. Control to supply the external power system with a surplus output obtained by removing the power supplied to the variable power utilization device from the power generated by the renewable energy power generation facility It is characterized by performing.

The invention of another form of the renewable energy output system is the invention of the above form,
The control unit is further capable of power generation control of a renewable energy power generation facility,
When the calculated power consumption of the variable power utilization device exceeds the upper limit power consumption of the variable power utilization device, the renewable energy power generation facility is commanded to suppress at least the excess output.

The invention of another form of the renewable energy output system is the invention of the above form,
The control unit receives the power supply / demand state of the external power system, and changes the coefficient of the function F in a direction to reduce the power consumption of the variable power utilization apparatus when the power demand is higher than a predetermined reference value. On the other hand, when the power supply amount is excessive from a predetermined reference value, the coefficient of the function F is changed to increase the power consumption of the variable power utilization apparatus.

The invention of another form of the renewable energy output system is the invention of the above form,
The renewable energy power generation facility is characterized by using wind power generation.

The invention of another form of the renewable energy output system is the invention of the above form,
The variable power utilization device uses a water electrolysis device.

  In another aspect of the invention of the renewable energy output system according to the aspect of the invention, the function F is an increasing function at least in a predetermined Pf range.

Renewable energy output fluctuation suppression method of the present invention,
A method for suppressing output fluctuations of a renewable energy output system that has a renewable energy power generation facility and a variable power utilization device and can supply a surplus output to an external power system,
Using an output Pf obtained by smoothing a time series output P of a renewable energy power generation facility with a certain time constant and a function F using Pf as a variable, Pe = P− [Pf−F (Pf)] (where F (Pf)) The power consumption Pe of the variable power utilization device is calculated from an expression expressed by:
Supplying power to the variable power utilization device from the power generated by the renewable energy power generation facility based on the calculation result,
A surplus output obtained by removing power supplied to the variable power utilization apparatus from the power generated by the renewable energy power generation facility is supplied to the external power system.

Renewable energy output fluctuation suppression program of the present invention,
For the renewable energy output system that has a renewable energy power generation facility and a variable power utilization device and can supply surplus output to an external power system, output fluctuation suppression executed by the controller that controls the power supply in the system A program,
Obtaining generated power information by the renewable energy power generation facility;
Using an output Pf obtained by smoothing a time series output P of a renewable energy power generation facility with a certain time constant and a function F using Pf as a variable, Pe = P− [Pf−F (Pf)] (where F (Pf)) Calculating the power consumption Pe of the variable power utilization apparatus from an expression expressed by: (maximum value of power = upper limit power consumption of the variable power utilization apparatus);
Instructing to supply power to the variable power utilization apparatus from the power generated by the renewable energy power generation facility based on the calculation result;
Instructing to supply to the external power system a surplus output obtained by removing power supplied to the variable power utilization apparatus from the power generated by the renewable energy power generation facility.

  That is, in order to solve the problems of the conventional system as described above, the present invention smooths the renewable energy power generation output in the system having the renewable energy power generation facility and the variable power utilization device, and then smoothes the output. The output offset in the direction of decreasing the output according to the size of the power is transmitted to the system, and the remaining output is consumed by the variable power utilization device.

Generally, in renewable energy power generation such as wind power and solar power, the output fluctuation range per unit time tends to increase as the ratio of the current output to the rated output increases. For example, FIG. 7 shows an example in which the maximum output drop after 1 second is plotted for each output ratio in the time series data of the actual windmill. From this graph, it can be understood that the larger the current output, the greater the expected output drop. Therefore, in order to transmit stable power to the grid, the offset width should be given a margin by increasing the power consumption of the variable power utilization device as the current output increases.
An example of a system output distribution method based on this is illustrated in FIG. First, the fluctuating renewable energy output is smoothed with an appropriate time constant. Subsequently, the offset width is determined by a function using the current output after smoothing as a variable. The function used at this time preferably takes into account the output fluctuation tendency as shown in FIG. Further, the function is such that the maximum value of the offset width is equal to the upper limit power of the variable power utilization device. Using the obtained offset width, the smoothed output is shifted downward. This smoothed offset output becomes the power transmission output to the power system. On the other hand, the difference between the current output before smoothing and the smoothed offset output is supplied to the variable power utilization apparatus.

As described above, the present invention smooths the renewable energy power generation output, transmits the output offset in the decreasing direction according to the magnitude to the power system, and uses the surplus in the variable power utilization device. Therefore, the following effects can be expected.
First, since the output in which the output fluctuation is suppressed as compared with the conventional system can be transmitted to the power system, the disturbance of the system frequency is less likely to occur. This facilitates system connection of a renewable energy power generation system to which the present invention is applied.
Next, since the maximum offset amount is made equal to the upper limit power of the variable power utilization device, the variable power utilization device can be operated efficiently, and an improvement in the facility utilization rate is expected.

It is a figure which shows the renewable energy output system in one Embodiment of this invention. Similarly, it is a graph which shows the distribution state of the output which shows the suppression result of a renewable energy output system. Similarly, it is a flowchart which shows the suppression method of a renewable energy output system. It is a figure which shows the renewable energy output system in other embodiment of this invention. Similarly, it is the graph which shows the distribution state of the output which shows the suppression result of a renewable energy output system similarly. Similarly, it is a flowchart which shows the suppression method of a renewable energy output system. It is a figure which shows the output fall rate in wind power generation. It is a graph which shows the distribution state of the output which shows the suppression result in this invention. It is a graph which shows the distribution state of the output by the conventional suppression method.

Below, the renewable energy output system of this invention is demonstrated based on an accompanying drawing.
The renewable energy output system 1 of this embodiment rectifies AC power supplied to the wind power generator 2, the water electrolysis device 4, the controller 3 that controls the renewable energy output system 1, and the water electrolysis device 4. And a rectifier 5. In the renewable energy output system 1, surplus power can be supplied to the external power system 100. The electric power system 100 is not included in the renewable energy output system 1 of the present invention.
The wind power generator 2 corresponds to the renewable energy power generation facility of the present invention, and the water electrolysis device 4 corresponds to the variable power utilization device of the present invention.

  The renewable energy power generation equipment targeted in the present invention includes power generation equipment using sunlight, solar heat, wind power, hydropower, wave power, tidal power, geothermal heat, etc., but uses energy existing in the natural world. The type of power generation equipment is not limited. As variable power utilization devices, water electrolysis devices, heaters, water heaters, steam generators, heat pumps, water treatment devices, etc., devices that can consume variable power for applications with relatively little problem even if there is a time difference between supply and demand Is mentioned. Among them, the water electrolysis apparatus includes a solid polymer type, an alkaline water electrolysis type, a high temperature water electrolysis type, and the like, but any type can be used as long as it is an apparatus that consumes electric power and obtains hydrogen from water.

  The controller 3 corresponds to a control unit of the present invention, and has a CPU and a program for operating the CPU. When smoothing the program, operating parameters for the renewable energy power generation facility and the variable power utilization device, and power And a predetermined time constant, mathematical expression data regarding the function F, coefficient data in the function F, the upper limit power consumption of the variable power utilization device, and the like. The program includes the renewable energy output fluctuation suppressing program of the present invention.

The wind power generator 2 generally uses alternating current output, but the water electrolysis apparatus 4 uses direct current power, and therefore, the water electrolysis apparatus 4 is provided with a variable output type rectifier 5. Since the water electrolysis apparatus 4 has a characteristic that the water electrolysis voltage increases as the current density increases, the rectifier 4 also needs to be provided with a DC voltage adjustment function according to the control output. The rectifier 5 can adjust the amount of power supplied to the water electrolysis device 4 under the control of the controller 3.
However, due to the characteristics of the water electrolysis apparatus 4, if the operation is stopped and it takes time to restart or the life is adversely affected, the water electrolysis apparatus 4 is operated at a low load even during a time period when the wind turbine output is low. It is desirable to keep it.

  Below, the distribution example of the system | strain supply output and water electrolysis power consumption in the renewable energy output system 1 is shown in FIG. Moreover, the flowchart of FIG. 3 shows the procedure of the method for suppressing the renewable energy output. The following procedure is executed by the controller 3 that operates according to the renewable energy output fluctuation suppression program.

Along with the start of the procedure, first, the output distribution controller 3 measures the wind turbine output P _wt (step S1), and performs a smoothing process on this data (step S2). The controller 3 may receive the measurement result without directly measuring the output.
As the smoothing method, a first-order lag method, a moving average method, or the like can be used. In the present invention, the smoothing method is not particularly limited. The smoothing time constant depends on the fluctuation acceptability of the power system (for example, determined by the capacity of an adjustable power source (thermal power plant, hydropower plant, etc.) in the target power pipe, but a range of 600 seconds to 3600 seconds is preferable. . Further, the time constant is not fixed, and can be changed by appropriate conditions.

Subsequently, P _f obtained by smoothing the wind turbine output P _wt is substituted into the offset function F (step S3). The form of the function F can be considered as follows. The mathematical formula of the function F can be stored in the storage unit of the controller 3 and read out for use in the calculation.
F = a1 × P _f + c
F = a2 × P _f ^b + d
Here, a1, a2, b, c, and d are predetermined coefficients. The coefficients a1, a2, and b can be selected from any number other than 0, but for the reasons listed in the next paragraph, a positive number that is an increasing function of Pf is more preferable. On the other hand, the coefficients c and d can be selected from all numbers including 0.

As described above, because the wind turbine output is higher the greater the output fluctuation width increases, as shown in FIG. 2, preferably keep a higher P _f increases function F also such larger relationship (increasing function). The region that becomes the increase function may be satisfied for all output values regardless of P _f , but the second-order or third-order or higher-order equation that becomes the increase function in the range of the assumed output value. The function F may be used.
Further, one or more threshold values may be set for P _f , and the function form may be changed before or after the threshold value or may be set to a constant value. Since the offset amount finally becomes the power consumption of the water electrolysis apparatus, the coefficient is adjusted so that the maximum value of the function F becomes the upper limit power of the water electrolysis apparatus. In implementation, the function F may be converted into a table format and incorporated in the program.
By using the function F, the fluctuation of the system output is suppressed to be small with respect to the fluctuation of the windmill output.

As shown in the following equation, by subtracting the offset amount F from the smoothed output P _f, line output P _out is determined.
P _out = P _f −F (P _f )
Subsequently, the controller 3, the current of the wind turbine output P _wt, calculates an output obtained by subtracting the channel output P _out obtained above as a power P _el as shown in the following formula.
_{P el = P wt -P out =} P wt - (P f -F (P f))

However, before smoothing output P _wt and smoothed after the output P _f because there is no time zone coincides, rare in some cases water electrolysis power P _el exceeds the upper limit power of a water electrolysis apparatus (step S4) . If water electrolysis power P _el exceeds the upper limit power of a water electrolysis apparatus (step s4, Yes), but the amount that deviates from the upper limit power is also a method of transmitting by adding to the system output P _out, in FIG. 4 As shown, it is also effective to command output suppression from the controller 3 to the wind power generator 2 (step S5). In this case, the power consumption is set to the upper limit power. After step S5, the process proceeds to step S6.

In the controller 3, the rectifier 5 is commanded with the calculated power consumption or the electric energy set to the upper limit power, and this electric power is converted into a direct current in the rectifier 5 from the wind turbine output _Pwt and supplied to the water electrolysis apparatus 4 ( Step S6).
After step S6, the controller 3 performs control to supply the surplus P _out from the wind turbine output P _wt , which is obtained by removing the power supplied to the water electrolysis device 4, to the external power system 100 (step S7). Next, it is determined whether or not to end (step S8).
If not completed (No at step S8), the process returns to step S1 and the same procedure is repeated. If it is determined that the process is to be terminated (step S8, Yes), the procedure is terminated.

In this embodiment, power distribution is performed by the rectifier 5, but power distribution may be performed between the water electrolysis apparatus 4 and the power system 100 by installing a power distributor or the like.
The electric power supplied to the electric power system 100 has a stable output in which fluctuations are greatly suppressed compared to fluctuations in generated power.

Next, another embodiment will be described with reference to FIGS.
In this embodiment, a circuit for feeding back the supply and demand state of the power system is incorporated. Further, the same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

The power supply and demand status of the power system is notified from the external power system 100 to the controller 3A. The controller 3A has a control function based on the supply and demand state of the power system in addition to the function of the controller 3 of the embodiment.
Steps S10 (power amount income) and S11 (smoothing) in this embodiment are the same as steps S1 and S2 in the first embodiment, and the description thereof is omitted.
The controller 3A acquires the supply and demand state of the external power system (step S12), and determines whether the demand amount and the supply amount within a predetermined standard are satisfied (step S13).
The predetermined reference is stored in the storage unit of the controller 3A and is read out as necessary.

  In the controller 3A, when the supply and demand state of the external power system does not satisfy the predetermined standard (No in Step S13), it is determined whether the demand amount is higher than the standard (Step S14). When the demand amount is high (step S14, Yes), as shown in FIG. 5, the system output is emphasized, and the coefficient in the function F is changed so as to reduce the variable power usage amount and increase the supply amount. The coefficient to be changed may be determined in advance, or the coefficient may be changed according to the degree to which the demand amount exceeds the standard. The coefficient can be stored in the storage unit of the controller 3 as a numerical value or a calculation formula.

  Further, when the demand amount is not high (No in step S14), the supply amount is excessive. Therefore, as shown in FIG. 5, a function is given to increase the variable power usage amount and decrease the supply amount with an emphasis on water electrolysis. The coefficient in F is changed (step s15). The coefficient to be changed may be determined in advance, or the coefficient may be changed according to the degree to which the demand amount exceeds the standard. The coefficient can be stored in the storage unit of the controller 3 as a numerical value or a calculation formula.

In step s13, when the supply and demand state of the external power system satisfies a predetermined reference value (step S13, Yes), or after steps S15 and S16, the power consumption supplied to the variable power utilization device is calculated by the function F. (Step S17).
As a result of the calculation, it is determined whether the water electrolysis power consumption _Pel exceeds the upper limit power of the water electrolysis apparatus (step S18). When the water electrolysis power consumption _Pel exceeds the upper limit power of the water electrolysis apparatus (step S18, Yes), the controller 3A instructs the wind power generator 2 to suppress the deviation output (step S19). In this case, the power consumption is set to the upper limit power. After step S19, the process proceeds to step S20.

On the other hand, when the water electrolysis power consumption _Pel does not exceed the upper limit power of the water electrolysis apparatus (No in step S18), the process proceeds to step S20. In step S <b> 20, the rectifier 5 is commanded with the calculated power consumption or the amount of power set to the upper limit power, and this power is converted into a direct current and supplied to the water electrolysis device 5. After step S20, the controller 3 performs control to supply P _out to the external power system 100 (step S21). Next, it is determined whether or not to end (step S22).
If not completed (No at Step S22), the process returns to Step S10 and the same procedure is repeated. When it is determined that the process is to be ended (step S22, Yes), the procedure is ended.

  In the above embodiment, the distribution rule is changed as shown in FIG. 5 by dynamically adjusting the coefficient of the offset function F according to the power demand state of the system. When the power demand is large, the distribution rule is changed so that the system output becomes as large as possible. On the other hand, when the power demand is small, the grid output is suppressed, and instead, the distribution rule is set such that the water electrolysis apparatus can be operated near the rated output. Moreover, if the feedback of the grid supply and demand and the output suppression of the windmill are combined, more effective operation is possible and the usefulness of the present invention can be enhanced.

  As mentioned above, although this invention was demonstrated based on the said embodiment, unless it deviates from the scope of the present invention, an appropriate change with respect to the said embodiment can be made.

DESCRIPTION OF SYMBOLS 1 Renewable energy output system 1A Renewable energy output system 2 Wind power generator 3 Controller 3A Controller 4 Water electrolysis apparatus 5 Rectifier 100 Electric power system

Claims (8)

In a renewable energy output system having a renewable energy power generation facility and a variable power utilization device and capable of supplying surplus output to an external power system,
Obtaining generated power information by the renewable energy power generation facility, comprising a control unit for controlling the power supply amount consumed by the variable power utilization device among the generated power,
The control unit uses an output P _{f obtained} by smoothing the time series output P of the renewable energy power generation facility with a predetermined time constant and a predetermined function F using P _f as a variable, and P _e = P− [P _f -F _{(P f)]} (the maximum value of the proviso F (P _f) = variable power usage limit power consumption device) calculates the power consumption P _e of the variable power utilization device from the equations represented by the power consumption computed From the power generated by the renewable energy power generation facility to the variable power utilization device, and from the power generated by the renewable energy power generation facility, the surplus output obtained by removing the power supplied to the variable power utilization device A renewable energy output system characterized by performing control to be supplied to an external power system. The control unit is further capable of power generation control of a renewable energy power generation facility,
The regeneration according to claim 1, wherein when the calculated power consumption of the variable power utilization device exceeds the upper limit power consumption of the variable power utilization device, the renewable energy power generation facility is instructed to suppress at least the excess output. Possible energy output system.   The control unit receives the power supply / demand state of the external power system, and changes the coefficient of the function F in a direction to reduce the power consumption of the variable power utilization device when the power demand is higher than a predetermined reference value. 3. The renewable energy according to claim 1, wherein the coefficient of the function F is changed in a direction of increasing the power consumption of the variable power utilization device when the power supply amount is excessive than a predetermined reference value. Output system.   The renewable energy output system according to any one of claims 1 to 3, wherein the renewable energy power generation facility uses wind power generation.   The renewable energy output system according to any one of claims 1 to 4, wherein the variable power utilization device uses a water electrolysis device. Wherein the function F is in the range of at least a predetermined P _f, renewable energy output system according to any one of claims 1 to 5, characterized in that is an increasing function. A method for suppressing output fluctuations of a renewable energy output system that has a renewable energy power generation facility and a variable power utilization device and can supply a surplus output to an external power system,
Using an output P _{f obtained} by smoothing the time series output P of the renewable energy power generation facility with a certain time constant and a function F using P _f as a variable, P _e = P− [P _f −F (P _f )] ( However calculates the power P _e of the variable power utilization device from the equations represented by F maximum value = the upper limit power consumption of the variable power utilization apparatus (P _f)),
Supplying power to the variable power utilization device from the power generated by the renewable energy power generation facility based on the calculation result,
A surplus output obtained by excluding the power supplied to the variable power utilization apparatus from the power generated by the renewable energy power generation facility is supplied to the external power system. For the renewable energy output system that has a renewable energy power generation facility and a variable power utilization device and can supply surplus output to an external power system, output fluctuation suppression executed by the controller that controls the power supply in the system A program,
Obtaining generated power information by the renewable energy power generation facility;
Using an output P _{f obtained} by smoothing the time series output P of the renewable energy power generation facility with a certain time constant and a function F using P _f as a variable, P _e = P− [P _f −F (P _f )] ( However a step of computing the power consumption P _e of the variable power utilization device from the equation expressed by F maximum value = the upper limit power consumption of the variable power utilization apparatus (P _f)),
Instructing to supply power to the variable power utilization apparatus from the power generated by the renewable energy power generation facility based on the calculation result;
An instruction to supply the external power system with a surplus output excluding the power supplied to the variable power utilization device out of the power generated by the renewable energy power generation facility. Fluctuation control program.

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