A maximum power point tracking method and a solar power generation system

Abstract

A maximum power point tracking (MPPT) method and a solar power generation system are disclosed. The method generates a power variation index by detecting data from the solar power generation system at multiple time points. Based on the current power change, current voltage change, and the MPPT index, a reference voltage value and a control signal are generated. An output power value is then generated based on the reference voltage value. The control signal is used to adjust the output voltage, which is proportional to the reference voltage value. By using the reference voltage value, the method effectively increases the efficiency of the solar power generation system's output power value, effectively reduces severe oscillations at the operating point corresponding to the reference voltage value when illuminance changes significantly, and effectively ensures that the output power value corresponding to the reference voltage value approaches the maximum power point at the current illuminance.

Claims

1. A maximum power point tracking method, applicable to a solar power generation system, comprising the following steps: (A) detecting the voltage and current output by the solar power generation system at multiple time points to generate detection data, the detection data including multiple detected voltage values ​​corresponding to different time points and multiple detected current values ​​corresponding to different time points; (B) generating a power variation index based on the detection data, the power variation index being related to the product of a current power change and a previous power change; (C) generating a first voltage adjustment value or a second voltage adjustment value based on a judgment of the current power change, a current voltage change, and the power variation index, wherein, The first voltage adjustment value is proportional to the negative current voltage change, and the second voltage adjustment value is proportional to the current voltage change; (D) Based on the first voltage adjustment value or the second voltage adjustment value from step (C) and a current voltage value, a reference voltage value and a control signal are generated, the control signal being used to adjust the magnitude of an output voltage proportional to the reference voltage value.

2. The maximum power point tracking method as described in claim 1, wherein, The detected voltage values ​​at the multiple different time points in step (A) are a current voltage value, a previous voltage value, and a previous second voltage value, respectively. The detected current values ​​at the multiple different time points are a current value, a previous current value, and a previous second current value, respectively.

3. The maximum power point tracking method as described in claim 2, wherein, Step (B) includes: (B1) generating the current voltage change based on the current voltage value and the previous voltage value; (B2) generating a current current change based on the current current value and the previous current value; (B3) generating the current power change based on the current power value and the previous power value; (B4) generating the previous power change based on the previous power value and a previous two power values; and (B5) generating the power variation index based on the current power change and the previous power change.

4. The maximum power point tracking method as described in claim 3, wherein, This step (B5) uses the following formula: P(s) = × , where the parameter P(s) is defined as the power change index, the parameter is defined as the current power change, and the parameter is defined as the previous power change.

5. The maximum power point tracking method as described in claim 3, wherein, Step (C) includes: (C0) determining whether the current power change is greater than zero; (C1) if the current power change in step (C0) is greater than zero, then determining whether the current voltage change is greater than zero; (C4) if the current voltage change in step (C1) is less than zero, then determining whether the power variation index is less than zero; (C40) if the power variation index in step (C4) is less than zero, then determining whether the power variation index is greater than zero; (C31) if the power variation index in step (C4) is greater than zero, then generating a first scaling function based on the ratio of the current current change to the current voltage change to the current current value to the current voltage value; (C32) generating a first voltage adjustment value based on the negative value of the current voltage change and the first scaling function; (C33) if the power variation index in step (C40) is greater than zero, then generating a second scaling function based on the ratio of the current current change to the current voltage change to the current current value to the current voltage value. (C34) The second voltage adjustment value is generated based on the current voltage change and the second scaling function.

6. The maximum power point tracking method as described in claim 5, wherein, The step (C) further includes: (C2) if the current power change in step (C0) is less than zero, then determine whether the current voltage change is greater than zero; (C3) if the current voltage change in step (C1) is greater than zero, then determine whether the current current change is greater than zero. (C5) If the current voltage change in step (C2) is less than zero, then determine whether the current current change is greater than zero; wherein, if the current voltage change in step (C2) is greater than zero, if the power change index in step (C40) is less than zero, and if the current current change in step (C5) is less than zero, then proceed to step (C31); wherein, if the current current change in step (C3) is less than zero, and if the current current change in step (C5) is greater than zero, then proceed to step (C33).

7. The maximum power point tracking method as described in claim 5, wherein, Step (C31) uses the following formula: F = 1 - , where the parameter F is defined as the first scaling function, the parameter is defined as the current change, the parameter is defined as the current voltage change, and the parameter is defined as the ratio of the current value to the current voltage value; Step (C32) uses the following formula: ×F; Step (C33) uses the following formula: G = 1 - , where the parameter G is defined as the second scaling function; Step (C34) uses the following formula: ×G.

8. The maximum power point tracking method as described in claim 5, wherein step (D) includes: (D1) Based on the first scaling function in step (C31), generate a smoothing coefficient equal to the first scaling function; (D2) Based on the smoothing coefficient, the current voltage value, and the previous voltage value, generate the reference voltage value using the following formula: Vref=(1-α) ×V(n)+α×V(n-1), where parameter α is defined as the smoothing coefficient, parameter V(n-1) is defined as the previous voltage value, parameter V(n) is defined as the current voltage value, and parameter Vref is defined as the reference voltage value; (D3) Based on the reference voltage value, generate the output power value and a triangular wave with a fixed frequency, and based on the triangular wave and the reference voltage value, generate a control signal proportional to the reference voltage value.

9. The maximum power point tracking method as described in claim 5, wherein step (D) includes: (D1) Based on the second scaling function in step (C33), generate a smoothing coefficient equal to the second scaling function; (D2) Based on the smoothing coefficient, the current voltage value, and the previous voltage value, generate the reference voltage value using the following formula: Vref=(1-α) ×V(n)+α×V(n-1), where parameter α is defined as the smoothing coefficient, parameter V(n-1) is defined as the previous voltage value, parameter V(n) is defined as the current voltage value, and parameter Vref is defined as the reference voltage value; (D3) Based on the reference voltage value, generate an output power value and a triangular wave with a fixed frequency, and based on the triangular wave and the reference voltage value, generate a control signal proportional to the reference voltage value.

10. A solar power generation system, comprising: a solar cell unit for generating voltage and current at multiple time points based on light under different illuminance levels; a signal processing unit electrically connected to the solar cell unit for executing any of the maximum power point tracking methods of claims 1 to 9, generating a reference voltage value and a control signal based on the voltage and current at the multiple time points, and generating an output power value based on the reference voltage value, the control signal being used to adjust the magnitude of an output voltage proportional to the reference voltage value; and a voltage conversion module electrically connected to the solar cell unit and the signal processing unit for generating the output voltage based on the control signal.

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