JP2018007323A - Power variation control device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means capable of maintaining a power variation suppression function even when power generation output of a renewable energy power generation device varies.SOLUTION: A power variation control device for controlling an output variation of a power generation device for generating power using renewable energy includes a general controller including an output correction unit including: a stored energy detection unit for detecting a power storage amount of a power storage device; a constraint condition storage unit in which a constraint condition for power to be supplied to a power system is stored; a system output upper limit value calculation unit for calculating an upper limit value of system output, the sum of output power of the power generation device and output power of the power storage device; and a system target output setting unit for setting a target value for the system output on the basis of the upper limit value. The system output upper limit value calculation unit calculates the upper limit value of the system output so that the amount of power in the case of reducing the system output for a predetermined time on the basis of the constraint condition is equal to or lower than the power storage amount.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a power fluctuation control apparatus and method for controlling output fluctuation of a renewable energy power generation apparatus.

  In recent years, introduction of power generation devices using renewable energy (natural energy) such as a solar power generation system has been promoted due to environmental problems and the like. However, since renewable energy such as sunlight and wind power has a large fluctuation due to weather, there is a possibility of causing voltage fluctuation and frequency fluctuation to the power system connected to the renewable energy power generation apparatus.

  As a countermeasure, a renewable energy power generation device is provided with a storage battery system for suppressing fluctuations, and the output of the power system is smoothed by appropriately charging and discharging the storage battery system according to the output change of the renewable energy power generation device. A method has been proposed.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for giving a control command so as to compensate by charging / discharging of the power storage system in order to control fluctuations in the output power of the wind turbine generator group within a predetermined outputable range. Patent Document 2 discloses a control technique that causes a storage battery system having photovoltaic power generation to discharge beyond the limit range even after the charge level of the storage battery reaches a lower limit value.

JP 2013-219941 A JP 2012-210077 A

  In the conventional technology, when the power generation output of the renewable energy power generation device is surplus, the storage battery is charged, and conversely, when the power generation output is insufficient, the storage battery is discharged to cause voltage fluctuation or frequency fluctuation in the connected power system. Suppresses the occurrence. Therefore, the sum of the power generation output of the renewable energy power generation apparatus and the charge / discharge output from the storage battery is the output of the entire system.

  However, for example, if it suddenly becomes cloudy or the wind stops and the state continues for a long time, the power generation output of the renewable energy power generation device decreases for a long time. In this case, in order to keep the fluctuation of the system output within the allowable range, it is necessary to prepare a large-capacity storage battery. This is because if the capacity of the storage battery is insufficient, the fluctuation amount of the system output exceeds the allowable range of the power system, which may affect stable power supply and quality maintenance. However, as the storage battery becomes larger, the introduction cost increases and a larger installation area is required.

  The present invention has been made in view of the above problems, and its purpose is to suppress power fluctuation when a state in which the power generation output of a renewable energy power generation device suddenly decreases continues for a long period of time and the state of charge of the battery reaches the lower limit. Is to provide a power fluctuation control device and a power fluctuation control method.

  In order to solve the above-described problem, the present invention provides a power fluctuation control device that uses a power storage device to control output fluctuations of a power generation device that generates power using renewable energy, and the power storage amount of the power storage device is reduced. Calculates the upper limit value of the system output that is the sum of the output power of the power generation device and the output power of the power storage device A system output upper limit calculation unit, and a system target output setting unit that sets a system output target value based on the upper limit value, and the system output upper limit calculation unit includes the constraint condition Based on the above, the upper limit value of the system output is calculated so that the amount of power when the system output is reduced for a predetermined time is equal to or less than the charged amount.

  According to the present invention, even when the power generation output of the renewable energy power generation apparatus is in a state of sudden decrease, it is possible to suppress fluctuations in the system output and maintain high power quality of the system.

An overall view of a renewable energy power generation system is shown. A block diagram of the general controller is shown. The block diagram which shows the detail of a system target output calculating part is shown. The block diagram which shows the detail of an output correction | amendment part is shown. The schematic diagram which shows the calculation method of a system output upper limit calculation part is shown. The schematic diagram which shows the function of a system target output setting part is shown. The schematic diagram which shows transition of a power generation output and a system output is shown. The block diagram of the output correction | amendment part in the case of not providing the restriction | limiting of the output W at the time of the rapid decrease of an electric power generation output is shown. The schematic diagram of the system output change method at the time of sudden reduction of a power generation output is shown. The schematic diagram of the method of determining a system output change speed is shown. The schematic diagram of the system output change method at the time of sudden reduction of a power generation output is shown.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The power fluctuation control device 3 of the renewable energy power generator according to this embodiment will be described. In the present embodiment, a solar power generation device will be described as an example of a renewable energy power generation device, but the present invention is not limited to this and can be applied to a wind power generation device or the like.

  The power generation system 1 of the present embodiment includes a power control device 3 as a “power fluctuation control device” that suppresses fluctuations in the system output Psys, which is the sum of the power generation output Ppv of the power generation device and the charge / discharge output Pbatt of the storage battery 7. .

  The power control device 3 includes a smoothing unit 911 (see FIG. 2) that smoothes the power generation monitor signal of the power generation device. The power control device 3 has a target value correction function for correcting a deviation between the power generation output Ppv and the system output Psys. When the power generation output Ppv decreases, the target value correcting function decreases the system output Psys following the decrease. In addition, the power control device 3 includes an output correction unit 92. The output correction unit 92 has a function of correcting the output in accordance with the SOC (State Of Charge) or SOH (State Of Health) of the storage battery 7, and the charge / discharge Pbatt of the storage battery 7 is also reduced when the power generation output Ppv suddenly decreases. Maintains power fluctuation suppression function without running out.

  According to the present embodiment, the fluctuation of the system output Psys can be limited within a desired output fluctuation range, and the power quality can be maintained.

  A first embodiment will be described with reference to FIGS. FIG. 1 shows a schematic overall configuration diagram of a photovoltaic power generation system 1. The solar power generation system 1 includes, for example, a solar panel 4, a solar power conditioner (PCS) 5 (hereinafter referred to as a solar PCS 5), and a storage battery system 2. Hereinafter, the solar panel 4 and the solar PCS 5 are collectively referred to as a solar power generation device or a power generation device.

  The storage battery system 2 compensates the power generation output Ppv of the solar power generation device by the charge / discharge Pbatt of the storage battery 7. The storage battery system 2 includes, for example, a storage battery 7, a storage battery power conditioner 6 (hereinafter referred to as storage battery PCS 6), and a power control device 3.

  The power control device 3 includes, for example, a general controller 9. The power control device 3 further includes an external controller 10 that can communicate with the overall controller 9 via a communication network 8 such as the Internet, and a terminal 11 that is connected to the external controller 10 by a serial bus or a parallel bus. Also good. The detailed configuration of the overall controller 9 will be described later with reference to FIGS.

  By connecting the storage battery system 2 to an existing or newly installed solar power generation apparatus (solar panel 4 and solar PCS 5), the solar power generation system 1 of the present embodiment can be easily configured.

  Moreover, the solar power generation system 1 of this embodiment can be easily configured by connecting the power control device 3 to the existing solar panel 4, storage battery 7, solar PCS5, and storage battery PCS6. it can. The solar PCS 5 and the storage battery PCS 6 are connected at a connection point CP, and the connection point CP is connected to the power system 12.

  The power control device 3 can also correspond to a plurality of solar power generation devices. That is, by connecting one power control device 3 to a plurality of solar power generation devices, the difference between the power generation output Ppv of each solar power generation device and the system output Psys can be reduced.

  The solar panel 4 generates power using sunlight. The generated power Ppv of the solar panel 4 is converted from direct current to alternating current by the solar PCS 5 and supplied to the power system 12. Here, the solar panel 4 is made of, for example, a silicon type such as a single crystal silicon type, a polycrystalline silicon type, a microcrystalline silicon type, an amorphous silicon type, or a compound such as InGaAs, GaAs type, CIS type (calcobarite type), etc. It can be configured by connecting a plurality of solar cells in series and parallel. An organic solar panel 4 using a dye-sensitized solar cell or an organic thin-film solar cell may be used.

  On the other hand, the storage battery 7 charges and discharges charging / discharging power Pbatt to the power system 12 via the storage battery PCS 6. The storage battery 7 is configured by a device that stores electric power using an electrochemical reaction such as a lead storage battery, a lithium ion storage battery, a nickel / hydrogen storage battery, or a sodium / sulfur battery. Moreover, you may use the apparatus which accumulate | stores as electrostatic energy or magnetic energy like an electrical double layer capacitor and superconducting magnetic energy storage. Moreover, you may use the apparatus which converts and accumulate | stores electric power into the kinetic energy and positional energy of an object, such as a flywheel and pumped-storage power generation.

  The system output Psys of the entire power generation system 1 for the power system 12 is a combined output of the power generation output Ppv and the charge / discharge power Pbatt, which is the power generated by the solar power generation device. The fluctuation of the power generation output Ppv due to the shade fluctuation component such as a cloud is canceled (compensated) by the charge / discharge power Pbatt, and the system output Psys is smoothed. That is, the storage battery system 2 has a fluctuation suppressing function that suppresses fluctuations in the power generation output Ppv.

  PCS 5 and 6 may be referred to as grid interconnection inverters. The power generation output Ppv of the solar panel 4 is output through the sunlight PCS 5. For this reason, the value of the power generation output Ppv is limited by the capacity of the solar PCS 5.

  As will be described in detail later, the overall controller 9 constituting the power control device 3 calculates a system target output Psys * that serves as a guide for fluctuation suppression, and calculates a charge / discharge target value Pb * based on the obtained system target output Psys *. Ask. Then, the overall controller 9 outputs the charge / discharge target value Pb * to the storage battery PCS 6.

  The overall controller 9 can acquire the power generation output monitor signal Ppv_fb from the PCS 5 for sunlight and the SOC from the storage battery 7 respectively regularly or irregularly. The power generation output monitor signal Ppv_fb is a monitor signal of the power generation output Ppv, and is measured by the sunlight PCS 5. It is good also as a structure which measures the electric power generation output monitor signal Ppv_fb with the wattmeter etc. which are separately installed in PCS5 for solar power generation.

  Although FIG. 1 shows a case where the PCS 5 for sunlight and the PCS 6 for storage battery are each installed alone, the present invention is not limited to this. For example, in a large-scale photovoltaic power generation system 1 such as a mega solar equipped with a large number of solar panels 4, a plurality of solar PCSs 5 are installed according to the plurality of solar panels 4, and a plurality of storage batteries 7 are supported. A plurality of storage battery PCSs 6 may be installed. In this case, the overall controller 9 calculates the system target output Psys * as the total value of the plurality of solar PCSs 5. Similarly, the overall controller 9 calculates the charge / discharge target value Pb * as the total value of the plurality of power storage PCSs 6.

  The power control device 3 can also be controlled via an external controller 10 installed at a location away from the power generation system 1. The operator can operate the terminal 11 to access the overall controller 9 via the external controller 10 and input setting values and the like. The operator can also display the state of the power generation system 1 on the terminal 11.

  FIG. 2 is a functional block diagram of the overall controller 9. The overall controller 9 calculates the charge / discharge target value Pb * based on the power generation output monitor signal Ppv_fb input from the solar PCS 5 as will be described later.

  The overall controller 9 includes, for example, a system target output calculation unit 91 and an output correction unit 92. The system target output calculation unit 91 calculates the system target output Psys ** based on the power generation output monitor signal Ppv_fb input from the solar PCS 5. The system target output Psys ** is a target value of the generated power output from the power generation system 1.

  The system target output calculation unit 91 obtains a system target output Psys ** by performing a low-pass filter calculation such as a moving average method and a first-order lag as a smoothing calculation, and outputs the system target output Psys ** to the output correction unit 92.

  FIG. 3 is a functional block diagram of the system target output calculation unit 91. The system target output calculation unit 91 includes, for example, a smoothing unit 911 and a target value correction unit 912.

  The smoothing unit 911 calculates the system target output Psys *** by performing a low-pass filter operation such as a moving average on the power generation output monitor signal Ppv_fb. The system target output Psys *** before correction corresponds to the “first output target value”.

  The target value correcting unit 912 corrects and outputs the system target output Psys ***. The target value correction unit 912 includes, for example, an output change calculation unit 9121, a constraint condition storage unit 9122, and a correction amount calculation unit 9123.

    The output change calculation unit 9121 calculates the degree of divergence between the system target output Psys *** and the power generation output monitor signal Ppv_fb. The constraint condition storage unit 9122 stores conditions that the system output should observe. As a constraint condition, for example, there is a change rate per unit time. Here, it is assumed that the power generation system 1 must supply power to the power system 12 within the range of the change rate negotiated with the power transmission / distribution company, and the change rate is expressed as nW / min (n is It is expressed as a positive number).

  The correction amount calculation unit 9123 corrects the system target output Psys *** within a range satisfying the constraint condition when the degree of deviation between the system target output Psys *** and the power generation output monitor signal Ppv_fb exceeds a predetermined value. To do. The corrected system target output Psys ** corresponds to the “second output target value”.

  The output correction unit 92 corrects the system target output Psys ** corrected by the system target output calculation unit 91 based on the SOC of the storage battery 7.

  FIG. 4 shows details of the output correction unit 92. The output correction unit 92 includes, for example, an energy storage amount detection unit 921, a constraint condition storage unit 922, a system output upper limit value calculation unit 923, and a system target output setting unit 924.

  The stored energy amount detection unit 921 calculates an energy amount E that is currently stored in the storage battery 7 based on the SOC and SOH and that can be used to suppress fluctuations. The usable energy amount E can be calculated by a known method, but can be calculated as, for example, rated capacity × SOH × rated voltage × SOC / 100. The constraint condition storage unit 922 stores conditions that the system output should observe. Based on the usable energy amount E calculated by the stored energy amount detection unit 921, the system output upper limit value calculation unit 923 maintains the system output Psys with the nW / min restriction even if the power generation output Ppv suddenly becomes zero. W that can be changed from the current output W to zero is calculated.

  FIG. 5 is a schematic diagram illustrating a calculation method of the system output upper limit calculation unit 923. The time t when the current output W changes to zero is expressed as W / n. The amount of energy required at this time is W × t / 2, which is expressed as W ^ 2 / 2n. The system output upper limit calculation unit 923 determines W so that the required energy amount W 2 / 2n is equal to or less than the usable energy amount E. Here, the case where nW / min, which is the upper limit of the allowable output change rate, is shown, but it may be set smaller than nW / min.

  FIG. 6 is a schematic diagram showing the function of the system target output setting unit 924. The broken line is an example where the required energy amount W 2 / 2n is equal to the usable energy amount E, and the solid line is an example when a margin is set. Since an error occurs in the usable energy amount E due to an error in SOC or SOH, it is preferable to set an appropriate margin so as to be below the broken line.

  The overall controller 9 calculates the charge / discharge target value Pb * from the difference between the system target output Psys * and the power generation output monitor signal Ppv_fb, and gives it to the storage battery PCS6.

  The limit of the output W in consideration of the usable energy amount E shown in the present embodiment may be always performed, or for example, the number of times deviating from the time or nW / min constraint may be input and used as a trigger. good. FIG. 7 is a schematic diagram in a case where the output W is not limited at the start of power generation and the output W is limited once when the number of deviations from the restriction of nW / min is set in solar power generation. After the power generation output rapidly decreases, the system output is decreased at nW / min, and the system output decreases rapidly when the state of charge reaches the lower limit. After that, due to the limitation of the output W, even if the power generation output increases, the system output is increased only in a stepwise manner, and it is possible to cope with the subsequent sudden decrease in the power generation output.

  FIG. 8 is a block diagram of the output correction unit 92 when no limitation is imposed on the output W when the power generation output suddenly decreases. The output correction unit 92 includes a system output upper limit excess value calculation unit 925 instead of or in addition to the system output upper limit value calculation unit 923. The following embodiment including this embodiment corresponds to a modification of the first embodiment, and therefore, the difference from the first embodiment will be mainly described.

  In the operation method shown in FIG. 7, there is a possibility of deviating from the limit of nW / min when the power generation output is suddenly reduced during the time when the limit of the output W is not provided. FIG. 9 shows that the threshold value E0 of the usable energy amount is held in the constraint condition storage unit 922 when the power generation output suddenly decreases, and the limit of nW / min is set before the usable energy amount reaches the threshold value E0. The system target output setting unit 924 outputs the system target output Psys *. After reaching the threshold value E0, the system target output setting unit 924 changes the system output at XW / min. By providing such a function, it is possible to reduce the adverse effect on the system when deviating from the restriction of nW / min.

  FIG. 10 is a schematic diagram showing an example of a calculation method of the output fluctuation speed XW / min under the condition that the usable energy amount reaches E0. From the same calculation as in the first embodiment, X is 2E0 / W ^ 2. By using X thus obtained, a rapid change in system output can be further reduced.

  In FIG. 9, the case where the amount of usable energy is changed at nW / min before reaching the threshold value E0 is described, but in this time domain, it may be nW / min or less. Further, after the amount of usable energy reaches the threshold value E0, the constant condition is XW / min. However, a plurality of threshold values may be provided to vary the system output at different output fluctuation speeds.

  In the second embodiment, the power generation output becomes zero at a certain time and the state continues. When the power generation output is not zero, the state fluctuates with time, so it is preferable to update the value using measurement data.

  In addition to measurement data, for example, when weather forecast data is available, it is possible to further reduce changes in system output. In FIG. 11, the amount of usable energy reaches the threshold value E0 at time t0, the system output is zero and the usable energy is zero at time t2. If it is predicted from the weather forecast data that the generated power will recover at a time t1 later than t0 and earlier than t2, XW / min so that the usable energy amount E0 is used in the period from time t0 to time t1. By determining, the output fluctuation speed can be made a value close to the reference value nW / min, and the change in the system output can be reduced.

DESCRIPTION OF SYMBOLS 1 Power generation system 2 Power storage system 3 Power control device 4 Solar panel 5 PCS for sunlight
6 PCS for storage battery
7 Storage Battery 9 General Controller 12 Power System 13 Solar Radiation Prediction Unit 91 System Target Output Calculation Unit 92 Output Correction Unit

Claims (10)

A power fluctuation control device that controls output fluctuation of a power generation device that generates power using renewable energy using a power storage device,
An energy storage detector for detecting the amount of electricity stored in the electricity storage device;
A constraint storage unit that stores constraints on the power supplied to the power system;
A system output upper limit value calculation unit that calculates an upper limit value of the system output that is the sum of the output power of the power generation device and the output power of the power storage device;
A system target output setting unit that sets a system output target value based on the upper limit, and an output correction unit including
The system output upper limit calculation unit calculates the upper limit value of the system output so that the electric energy when the system output is decreased for a predetermined time based on the constraint condition is equal to or less than the charged amount. To
Power fluctuation control device. The power fluctuation control device according to claim 1,
The power fluctuation control device according to claim 1, wherein the constraint condition defines a fluctuation amount per unit time of the system output. The power fluctuation control device according to claim 2,
The variation amount is set to nW / min (n is a positive number) or less, which is an upper limit of the output change rate, and the power variation control device. The power fluctuation control device according to claim 1 is:
A system target output calculation unit for calculating a target value of the system output;
The system target output calculator is
A power fluctuation control device that corrects the target value of the system output following the output power of the power generation device. The power fluctuation control device according to claim 4,
The system target output calculator is
A smoothing unit that calculates a first output target value of the system output by performing a low-pass filter operation on the output power of the power generation device;
A target value correcting unit for correcting the first output target value and calculating a second output target value;
A power fluctuation control device comprising: The power fluctuation control device according to claim 5,
The target value correction unit
An output change calculation unit for calculating a degree of divergence between the first output target value and the output power of the power generation device;
A constraint storage unit that stores constraints on the power supplied to the power system;
A power fluctuation control device comprising: The power fluctuation control device according to claim 6,
The target value correction unit
When the divergence degree exceeds a predetermined value, the power fluctuation control apparatus is characterized in that the second output target value is calculated by correcting the first output target value based on the constraint condition. The power fluctuation control device according to claim 1,
The output correction unit
An electric power fluctuation control device, wherein an upper limit value of the system output is calculated based on a predetermined time or the number of times deviating from the constraint condition. The power fluctuation control device according to claim 1,
The output correction unit
A system output upper limit excess calculating unit that calculates a system output when the system output deviates from the constraint condition;
The constraint condition storage unit holds a threshold value of the storage amount of the power storage device,
The system output upper limit excess value calculation unit calculates the upper limit value of the system output within the range of the constraint condition and deviates from the threshold value before deviating from the threshold value when the output power of the power generator decreases. Thereafter, the power fluctuation control device calculates the system output by a value exceeding a predetermined range of the upper limit value of the system output. A power fluctuation control method for controlling output fluctuation of a power generation apparatus that generates power using renewable energy using a power storage apparatus,
Based on the constraint condition of the power supplied to the power system, the power amount when the system output, which is the sum of the output power of the power generation device and the output power of the power storage device, is reduced for a predetermined time is the power storage amount of the power storage device An electric power fluctuation control method, wherein an upper limit value of the system output is calculated so as to be as follows, and a target value of the system output is calculated based on the upper limit value.

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