Power generation control system and power generation control method

Abstract

The present invention provides a power generation control system and a power generation control method that can improve the tracking ability of the maximum operating point while suppressing a decrease in power transmission efficiency. [Solution] The power generation control system 1 acquires the generated power P output from the power generation device 2 that converts renewable energy into electrical energy, and sets the maximum operating point P where the power value p of the acquired generated power P is maximized. Max The voltage value v Max The maximum operating point P obtained consecutively is detected at a sampling interval △t. Max The voltage value v Max And the maximum operating point P in this case Max The voltage value v Max The sampling interval △t is changed based on the absolute value of the variation △v, and the maximum operating point P is set at the changed sampling interval △t. Max The system is generally configured to include a control unit 5 that detects [something].

Description

Technical Field

[0001] The present invention relates to a power generation control system and a power generation control method.

Background Art

[0002] As a conventional technique, there is known a power generation system that obtains a solar cell current value at a point where the solar cell power obtained from the solar cell voltage and the solar cell current is maximized (see, for example, Patent Document 1).

[0003] This power generation system can improve the MPPT (Maximum Power Point Tracking) efficiency.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In such a conventional power generation system, when detecting the maximum operating point, which is the point where the solar cell power is maximized, the maximum operating point is detected at a constant time interval. Therefore, if the time interval is increased, the followability of the maximum operating point with respect to changes in the environment around the solar cell decreases. On the other hand, if the time interval is decreased, while the followability increases, there is a problem that power consumption increases and power transmission efficiency decreases.

[0006] Therefore, an object of the present invention is to provide a power generation control system and a power generation control method that can improve the followability of the maximum operating point while suppressing a decrease in power transmission efficiency.

Means for Solving the Problems

[0007] One aspect of the present invention provides a power generation control system comprising: a control unit that acquires power generated from a power generation device that converts renewable energy into electrical energy; detects the voltage value of the maximum operating point at which the power value of the acquired power generated is maximized at predetermined time intervals; changes the time interval based on the absolute value of the change in the voltage value of the previous maximum operating point and the voltage value of the current maximum operating point obtained consecutively; and detects the maximum operating point at the changed time interval.

[0008] Furthermore, one aspect of the present invention provides a power generation control method that acquires power generated from a power generation device that converts renewable energy into electrical energy, detects the voltage value of the maximum operating point at which the power value of the acquired power generated is maximum at predetermined time intervals, changes the time interval based on the absolute value of the change in the voltage value of the previous maximum operating point and the voltage value of the current maximum operating point obtained consecutively, and detects the maximum operating point at the changed time interval. [Effects of the Invention]

[0009] According to the present invention, it is possible to improve the tracking ability of the maximum operating point while suppressing a decrease in power transmission efficiency. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is an example of a block diagram of a power generation control system according to an embodiment. [Figure 2] Figure 2 shows an example of a sampling interval when the absolute value of the variation amount according to the embodiment is less than or equal to a threshold. [Figure 3] Figure 3 shows an example of a sampling interval when the absolute value of the variation amount according to the embodiment is greater than the threshold value. [Figure 4] Figure 4 is a flowchart showing an example of the operation of the power generation control system according to the embodiment. [Modes for carrying out the invention]

[0011] (Summary of the embodiment) The power generation control system according to this embodiment is generally configured to include a control unit that acquires power generated from a power generation device that converts renewable energy into electrical energy, detects the voltage value of the maximum operating point at which the power value of the acquired power generated is maximum at predetermined time intervals, changes the time interval based on the ratio of the voltage value of the previous maximum operating point obtained consecutively to the voltage value of the current maximum operating point, and detects the maximum operating point at the changed time interval.

[0012] Another embodiment of the power generation control method includes acquiring power generated from a power generation device that converts renewable energy into electrical energy, detecting the voltage value of the maximum operating point at which the power value of the acquired power generated is maximum at predetermined time intervals, changing the time interval based on the absolute value of the change in the voltage value of the previous maximum operating point and the voltage value of the current maximum operating point obtained consecutively, and detecting the maximum operating point at the changed time interval.

[0013] This power generation control system and method change the time interval according to the absolute value of the voltage fluctuation, so compared to the case where the time interval is constant, it is possible to improve the tracking ability of the maximum operating point while suppressing the decrease in power transmission efficiency.

[0014] [Embodiment] (Overview of Power Generation Control System 1) Figure 1 is an example of a block diagram of a power generation control system according to an embodiment. Figure 2 is an example of a sampling interval when the absolute value of the fluctuation amount according to the embodiment is less than or equal to a threshold. Figure 3 is an example of a sampling interval when the absolute value of the fluctuation amount according to the embodiment is greater than a threshold. In Figure 1, the flow of the main signals and information is indicated by arrows. In Figures 2 and 3, the vertical axis is the voltage value v and the horizontal axis is time t.

[0015] In this embodiment, the power generation control system 1 sets the maximum operating point P at the sampling interval △t as a time interval when detection starts. Max It is configured to perform MPPT control to detect [something].

[0016] As shown in FIGS. 1 and 2, the power generation control system 1 acquires the generated power P output from the power generation device 2 that converts renewable energy into electrical energy, and the maximum operating point P at which the power value p of the acquired generated power P is maximized Max of the voltage value v Max is detected at the sampling interval Δt, and the previous maximum operating point P obtained continuously Max of the voltage value v Max and the current maximum operating point P Max of the voltage value v Max Based on the absolute value of the variation amount Δv, the sampling interval Δt is changed, and the maximum operating point P is detected at the changed sampling interval Δt Max It is roughly configured with a control unit 5 for detecting.

[0017] The power generation device 2 of the present embodiment is, as an example, a solar cell, but is not limited thereto, and any device that converts renewable energy such as a wind power generation device, a tidal power generation device, and a geothermal power generation device into electrical energy may be used.

[0018] As an example, the absolute value of the variation amount Δv in the present embodiment is the absolute value of the ratio of the voltage value v Max expressed as a percentage (%). The absolute value of this ratio is, for example, as shown in FIG. 2, the previous voltage value v n , the current voltage value v n+1 In the case of, |{(v n+1 / v n ) - 1}| × 100 (%) is calculated, but is not limited thereto. The threshold Th is, as an example, 1 to 15%, preferably 2 to 5%. The threshold Th in the present embodiment is, as an example, 3%, but is not limited thereto.

[0019] As will be described later, as an example, when the threshold Th is 3%, the control unit 5 sets the range of 0% or more and 1% or less as the allowable range 51. When the absolute value of the variation amount Δv is included in the allowable range 51, the control unit 5 continues to use it without changing the sampling interval Δt.

[0020] Here, as a modification, the control unit 5 is the previous maximum operating point P Max of the voltage value vMax And the maximum operating point P in this case Max The voltage value v Max The absolute value of the fluctuation amount △v can also be calculated based on the absolute value of the difference. This absolute value of the difference is, for example, the previous voltage value v as shown in Figure 2. n , the voltage value v n+1 In that case, |v n+1 -v n It is calculated using |.

[0021] Furthermore, the power generation control system 1 is generally configured to include a power conversion unit 4 and a storage unit 6, as shown in Figure 1 as an example. The power generation control system 1 may also be configured to include a power generation device 2, a drive circuit 7, and a load 8. The power generation control system 1 of this embodiment is configured to include a power generation device 2, a power conversion unit 4, a control unit 5, a storage unit 6, a drive circuit 7, and a load 8.

[0022] The power conversion unit 4 and the control unit 5 are configured as a single integrated circuit, for example, as a power conditioner 3, but are not limited to this configuration. The power conversion unit 4 also includes, for example, a measuring unit 40 for measuring a voltage value v. This measuring unit 40 may also be configured to measure a current value.

[0023] As shown in Figures 2 and 3, the control unit 5 increases the sampling interval △t to set the maximum operating point P when the absolute value of the fluctuation amount △v is less than or equal to the threshold Th. Max If the absolute value of the variation △v is detected and greater than the threshold Th, the sampling interval △t is shortened to set the maximum operating point P. Max It detects.

[0024] Furthermore, as shown in Figures 2 and 3, the control unit 5 increases the sampling interval △t by a preset first set time when increasing the sampling interval △t, and decreases the sampling interval △t by a preset second set time when decreasing the sampling interval △t.

[0025] In this embodiment, the first and second setting times may be the same, but may also be different. In this embodiment, the first and second setting times are referred to as setting time a. This setting time a is greater than zero and shorter than the sampling interval △t. Setting time a is set so that when the sampling interval △t is shortened, the sampling interval △t does not become zero.

[0026] The power generation control system 1 of this embodiment further lengthens or shortens the modified sampling interval △t based on the absolute value of the variation △v. In this case, the control unit 5 has a lower limit and an upper limit for the sampling interval △t, and makes changes within that range. For example, the control unit 5 has the range of the lower limit and upper limit as range information 52.

[0027] As a variation, the power generation control system 1 may lengthen or shorten the sampling interval △t when starting MPPT control based on the absolute value of the fluctuation amount △v.

[0028] Furthermore, the control unit 5 may change the sampling interval △t, or it may change the sampling interval △t as a result of changing the operating frequency.

[0029] (Configuration of power conversion unit 4) The power conversion unit 4 converts the generated power P generated by the power generation device 2 from DC to AC, and converts the AC power P AC The power is output to the drive circuit 7. The power conversion unit 4 is configured to output to the control unit 5 both the power value p obtained by varying the voltage value v of the generated power P based on the control signal S output from the control unit 5 and the varied voltage value v. The control unit 5 uses MPPT control based on this voltage value v and power value p to determine the maximum operating point P Max It detects.

[0030] (Configuration of the control unit 5) The control unit 5 is a microcomputer composed of, for example, a CPU (Central Processing Unit) that performs calculations and processing on acquired data according to a stored program, and semiconductor memories such as RAM (Random Access Memory) and ROM (Read Only Memory). The ROM stores, for example, a program 50 for the operation of the control unit 5. The RAM is used, for example, as a memory area to temporarily store calculation results.

[0031] The control unit 5 performs MPPT control according to program 50, for example, and sets the maximum operating point P Max The control unit 5 also has a threshold Th for changing the sampling interval △t during MPPT control. Furthermore, the control unit 5 has the above-mentioned tolerance range 51 and range information 52.

[0032] Specifically, the control unit 5 determines the maximum operating point P at the sampling interval △t when the absolute value of the voltage value v fluctuation amount △v is within the allowable range 51. Max The control unit 5 detects this. In other words, for example, if the threshold Th is 3% and 1% < absolute value of fluctuation amount △v ≤ 3%, the control unit 5 shortens the sampling interval △t, and if 0% ≤ absolute value of fluctuation amount △v ≤ 1%, that is, within the allowable range 51, it does not change the sampling interval △t and continues to use it.

[0033] (Configuration of memory unit 6) The storage unit 6 is, for example, a semiconductor memory, but is not limited thereto. The storage unit 6 has a maximum operating point P Max voltage value v Max The control unit 5 stores the history information 60 of the previous maximum operating point P. Max The voltage value v Max And the maximum operating point P in this case Max The voltage value v Max The absolute value of the fluctuation △v is calculated and compared with the threshold Th.

[0034] (Configuration of drive circuit 7) The drive circuit 7, for example, uses AC power P AC It is configured to generate a drive current I for driving the load 8 based on [the specified value].

[0035] (Configuration of load 8) Load 8 can be, for example, a motor or a rechargeable battery. If load 8 is a rechargeable battery, the drive circuit 7 is configured to perform a charging process for the rechargeable battery.

[0036] The MPPT control of this embodiment will be described below.

[0037] (Regarding MPPT control) • When the absolute value of the fluctuation amount △v is less than or equal to the threshold Th. In Figures 2 and 3, the black dot represents the maximum operating point P. Max This is shown in Figures 2 and 3, where the maximum operating point P is at time t. Max The voltage value of v Max The voltage value v in Figure 2 is shown. n , voltage value v n+1 and voltage value v n+2 The maximum operating point P is at time t+n△t, time t+(n+1)△t, and time t+(n+2)△t. Max The voltage value v Max This shows the voltage value v in Figure 3. m , voltage value v m+1 and voltage value v m+2 The maximum operating point P is at time t+m△t, time t+(m+1)△t, and time t+(m+2)△t. Max The voltage value v Max This shows that n and m are integers greater than or equal to 1.

[0038] Figure 2 shows that because the absolute value of the variation △v is small, if the sampling interval △t is short, the maximum operating point P Max This illustrates an example where an increased number of detections can actually lead to increased power consumption.

[0039] The control unit 5 determines the maximum operating point P at the nth time t+n△t. Max The voltage value v n This is stored in the storage unit 6 as history information 60.

[0040] Next, the control unit 5 determines the maximum operating point P at time t+(n+1)△t based on the sampling interval △t. Max The voltage value v n+1 When you obtain the previous voltage value v n Calculate the absolute value of the variation △v.

[0041] Next, the control unit 5 increases the sampling interval △t if the absolute value of the calculated fluctuation amount △v is less than or equal to the threshold Th. Specifically, the control unit 5 adds the set time a to the sampling interval △t, and sets the maximum operating point P at time t+(n+2)△t+a, rather than at time t+(n+2)△t. Max The voltage value v n+2 The control unit 5 will continue to use the sampling interval △t without making any changes if the absolute value of the variation amount △v is within the allowable range 51.

[0042] The control unit 5 controls the maximum operating point P Max The voltage value set to v Max The power conversion unit 4 controls the power conversion unit 4 by outputting a control signal S. Based on the control signal S, the power conversion unit 4 controls the voltage value v Max Based on this, the generated power P is AC power P AC It is converted to and output to drive circuit 7.

[0043] • When the absolute value of the fluctuation △v is greater than the threshold Th Figure 3 shows that because the absolute value of the variation △v is large, if the sampling interval △t is long, the maximum operating point P Max This illustrates an example of reduced responsiveness.

[0044] The control unit 5 determines the maximum operating point P at the mth time t+m△t. Max The voltage value v m This is stored in the storage unit 6 as history information 60.

[0045] Next, the control unit 5 determines the maximum operating point P at time t+(m+1)△t based on the sampling interval △t. Max The voltage value v m+1 When you obtain the previous voltage value vm Calculate the absolute value of the variation △v.

[0046] Next, if the absolute value of the calculated fluctuation amount △v is greater than the threshold Th, the control unit 5 shortens the sampling interval △t. Specifically, the control unit 5 divides the sampling interval △t by the set time a, and sets the maximum operating point P at time t+(m+2)△ta, rather than at time t+(m+2)△t. Max The voltage value v m+2 Obtain it.

[0047] The control unit 5 controls the maximum operating point P Max The voltage value set to v Max The power conversion unit 4 controls the power conversion unit 4 by outputting a control signal S. Based on the control signal S, the power conversion unit 4 controls the voltage value v Max Based on this, the generated power P is AC power P AC It is converted to and output to drive circuit 7.

[0048] Below, an example of the operation of the power generation control system 1 of this embodiment will be described according to the flowchart in Figure 4.

[0049] (operation) The control unit 5 of the power generation control system 1 controls the maximum operating point P at a sampling interval △t based on MPPT control. Max Detect (Step 1).

[0050] The control unit 5 continuously detects the maximum operating point P Max The voltage value v Max Based on this, calculate the absolute value of the variation △v (Step 2).

[0051] The control unit 5 compares the absolute value of the fluctuation amount △v with the threshold Th. If the absolute value of the fluctuation amount △v is less than or equal to the threshold Th (Step 3: Yes) and the absolute value of the fluctuation amount △v is outside the acceptable range 51 (Step 4: Yes), the control unit 5 changes the sampling interval △t to be longer by the set time a (Step 5).

[0052] If the modified sampling interval △t based on the range information 52 is between the upper and lower limits (Step 6: Yes), the control unit 5 confirms the change to the sampling interval △t (Step 7) and proceeds to step 1.

[0053] In step 3, if the absolute value of the fluctuation amount △v is greater than the threshold Th (Step 3: No), the control unit 5 shortens the sampling interval △t by a set time a (Step 8). If the changed sampling interval △t is between the upper and lower limits based on the range information 52, the control unit 5 confirms the change in the sampling interval △t (Step 7) and proceeds to step 1.

[0054] Furthermore, in step 4, if the absolute value of the fluctuation amount △v is within the allowable range 51 (Step 4: No), the control unit 5 continues to use the sampling interval △t without changing it (Step 9) and proceeds to step 1.

[0055] Furthermore, in step 6, if the sampling interval △t changed based on the range information 52 is not between the upper and lower limits (Step 6: No), the control unit 5 continues to use the sampling interval △t without changing it (Step 9) and proceeds to step 1.

[0056] (Effects of the embodiment) The power generation control system 1 according to this embodiment can improve the tracking performance of the maximum operating point while suppressing a decrease in power transmission efficiency. In MPPT control, when the sampling interval is long, the consumption of generated power P decreases, but the tracking performance of the maximum operating point decreases. Conversely, when the sampling interval is short, the tracking performance of the maximum operating point increases, but the generated power P is consumed in large quantities, so the AC power P supplied to the load 8 is reduced. AC The power transmission efficiency decreases. The power generation control system 1 of this embodiment has a continuous maximum operating point P Max The voltage value v MaxSince the sampling interval △t can be shortened or lengthened based on the absolute value of the variation △v, compared to the case where the sampling interval is fixed, the decrease in power transmission efficiency can be suppressed while reaching the maximum operating point P Max This can improve the tracking performance.

[0057] The power generation control system 1 sets the maximum operating point P when the absolute value of the fluctuation amount △v is large. Max By increasing the detection frequency and improving tracking performance, when the absolute value of the fluctuation amount △v is small, the maximum operating point P Max By reducing the detection frequency and suppressing power consumption, appropriate MPPT control is performed compared to detecting at a constant frequency, and the maximum operating point P Max This improves responsiveness and suppresses heat generation associated with power consumption.

[0058] The power generation control system 1 has a maximum operating point P. Max Since the tracking ability is improved, the power generation P can be maximized in response to changes in the environment surrounding the power generation device 2, compared to when the maximum operating point is detected at a fixed frequency.

[0059] Another embodiment involves acquiring the generated power P output from a power generation device 2 that converts renewable energy into electrical energy, and determining the maximum operating point P at which the power value p of the acquired generated power P is maximized. Max The voltage value v Max The maximum operating point P obtained from the previous instance is detected at predetermined time intervals (sampling interval △t). Max The voltage value v Max And the maximum operating point P in this case Max The voltage value v Max The sampling interval △t is changed based on the absolute value of the variation △v, and the maximum operating point P is set at the changed sampling interval △t. Max The program 50 may be provided as a computer-readable recording medium that contains the program 50, which is used to perform a power generation control method that includes detecting the power source.

[0060] The power generation control system 1 and power generation control method according to the above-described embodiment may, for example, be partially implemented by a computer program, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field Programmable Gate Array), depending on the application.

[0061] Although several embodiments and modifications of the present invention have been described above, these embodiments and modifications are merely examples and do not limit the invention as defined in the claims. These novel embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, not all combinations of features described in these embodiments and modifications are necessarily essential for solving the problem of the invention. Moreover, these embodiments and modifications are included in the scope and spirit of the invention, as well as in the invention described in the claims and its equivalents. [Explanation of symbols]

[0062] 1...Power generation control system, 2...Power generation device, 3...Power conditioner, 4...Power conversion unit, 5...Control unit, 6...Storage unit, 7...Drive circuit, 8...Load, 40...Measurement unit, 50...Program, 51...Tolerance range, 52...Range information, 60...History information

Claims

1. A power generation control system comprising: a control unit that acquires power generated from a power generation device that converts renewable energy into electrical energy; detects the voltage value of the maximum operating point at which the acquired power value is maximized at predetermined time intervals; changes the time interval based on the absolute value of the fluctuation between the voltage value of the previous maximum operating point and the voltage value of the current maximum operating point obtained consecutively; and detects the maximum operating point at the changed time interval.

2. The control unit detects the maximum operating point by increasing the time interval if the absolute value of the fluctuation amount is less than or equal to a threshold, and detects the maximum operating point by shortening the time interval if the absolute value of the fluctuation amount is greater than the threshold. The power generation control system according to claim 1.

3. The control unit, when increasing the time interval, increases the time interval by a preset first set time, and when shortening the time interval, shortens the time interval by a preset second set time. The power generation control system according to claim 2.

4. We acquire the generated electricity output from a power generation device that converts renewable energy into electrical energy. The voltage value at the maximum operating point where the acquired power value of the generated power is maximized is detected at predetermined time intervals. The time interval is changed based on the absolute value of the difference between the voltage value of the previous maximum operating point and the voltage value of the current maximum operating point, obtained consecutively. The maximum operating point is detected at the modified time interval. Power generation control method.

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