This application claims priority to Taiwan Application Serial Number 102141708, filed Nov. 15, 2013, which is herein incorporated by reference.
1. Field of Invention
The present invention relates to power generating technology. More particularly, the present invention relates to a power generation control system, a method and a non-transitory computer readable storage medium of the same.
2. Description of Related Art
Since energy demands are gradually increasing, the use of renewable energy becomes an important issue in the subject of energy development. The renewable energy is energy which comes from natural resources that are continually replenished. The renewable energy include such as solar energy, wind energy, hydroelectric energy, tide energy or biomass energy. In recent years, lots of researches focus on the solar energy. Hence, the solar energy is especially important.
However, a problem with renewable energy is that it is unstable. For example, the energy production of a solar cell system primarily depends on the weather conditions of the geographical location where the system is installed. When the angle of the sunlight changes or part of energy generation blocks in a solar cell module do not operate normally since they are blocked by objects such as buildings, the efficiency of the solar cell module greatly decreases if there is no countermeasure.
Accordingly, what is needed is a power generation control system, a method and a non-transitory computer readable storage medium of the same to efficiently maintain a steady output power even if the renewable energy generation module does not function normally.
An aspect of the present invention is to provide a power generation control system. The power generation control system includes a plurality of supplying power generation devices, a maximum power point tracking (MPPT) module, a power control module and a plurality of voltage control modules. The supplying power generation devices are electrically connected to form an array, each including an energy generation module and a maximum voltage point tracking (MVPT) module. The energy generation module generates an input supplying power. The MVPT module is electrically connected to the energy generation module for performing a MVPT process on the input supplying power to generate an output supplying power. The MPPT module is electrically connected to the supplying power generation devices for performing a MPPT process on a total output supplying power generated from the supplying power generation devices to generate a maximum supplying power having a maximum power. The power control module is electrically connected to the MPPT module for generating a first duty cycle control signal according to a total output voltage and a total output current of the total output supplying power to control the MPPT module to perform the MPPT process. Each of the voltage control modules is electrically connected to the MVPT module of one of the supplying power generation devices for generating a second duty cycle control signal according to an output voltage of the output supplying power to control the MVPT module to perform the MVPT process.
Another aspect of the present invention is to provide a power generation control method used in a power generation control system. The power generation control method includes the steps outlined below. A MVPT module in each of a plurality of supplying power generation devices connected in series is controlled to receive an input power generated from an energy generation module to generate an output supplying power. A MPPT module is controlled to generate a maximum supplying power having a maximum power according to a total output supplying power generated from the supplying power generation devices. A first duty cycle control signal is generated according to a total output voltage and a total output current of the total output supplying power to control the MPPT module to perform a MPPT process on the total output supplying power. A second duty cycle control signal is generated according to an output voltage of the output supplying power of each of the supplying power generation devices to control the MVPT module to perform the MVPT process on the output supplying power.
Yet another aspect of the present invention is to provide a non-transitory computer readable storage medium to store a computer program to execute a power generation control method used in a power generation control system. The power generation control method includes the steps outlined below. A MVPT module in each of a plurality of supplying power generation devices connected in series is controlled to receive an input power generated from an energy generation module to generate an output supplying power. A MPPT module is controlled to generate a maximum supplying power having a maximum power according to a total output supplying power generated from the supplying power generation devices. A first duty cycle control signal is generated according to a total output voltage and a total output current of the total output supplying power to control the MPPT module to perform a MPPT process on the total output supplying power. A second duty cycle control signal is generated according to an output voltage of the output supplying power of each of the supplying power generation devices to control the MVPT module to perform the MVPT process on the output supplying power.
These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims.
It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed.
The invention can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows:
Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
As illustrated in
A column of three supplying power generation devices 10A, 10B and 10C are exemplary illustrated in
The energy generation module 100 can be such as, but not limited to a solar cell module or other types of renewable energy generation module. The energy generation module 100 generates an input supplying power 11. The MVPT module 102 is electrically connected to the energy generation module 100 for performing a MVPT process on the input supplying power 11 to generate an output supplying power having an output voltage Vo1.
The MPPT module 12 is electrically connected to the two ends of the supplying power generation devices 10A, 10B and 10C for receiving a total output supplying power from the supplying power generation devices 10A, 10B and 10C. The total output supplying power has a total output voltage Vdc and a total output current Idc. The MPPT module 12 performs a MPPT process on the total output supplying power generated from the supplying power generation devices 10A, 10B and 10C to generate a maximum supplying power 13 having a maximum power. In an embodiment, the maximum supplying power 13 is further transmitted to a power grid 18. In an embodiment, the MPPT module 12 is integrated in a DC to AC (direct current to alternating current) converter (not illustrated) to perform the MPPT process when the DC-AC converter converts the total output supplying power in a DC form to an AC form.
The power control module 14 is electrically connected to the MPPT module 12 for generating a first duty cycle control signal 15 according to the total output voltage Vdc and the total output current Idc of the total output supplying power. The first duty cycle control signal 15 adjusts the duty cycle of the MPPT module 12 to perform the MPPT process.
In an embodiment, the power control module 14 further includes an analog to digital converter 140, a control unit 142 and a power stage regulator (PSR) unit 144. The analog to digital (A/D) converter 140 converts the total output voltage Vdc and the total output current Idc from the analog form to the digital form. The control unit 142 controls the power stage regulator unit 144 to generate the first duty cycle control signal 15 according to the total output voltage Vdc and the total output current Idc. In an embodiment, the control unit 142 determines a slope of a rate of power change of a total output power according to the total output voltage Vdc, the total output current Idc and an algorithm stored therein. The control unit 142 further determines that the total output supplying power reaches the maximum output power when an absolute value of the slope is smaller than a predetermined threshold value of the rate of power change.
It is noted that the configuration of the power control module 14 illustrated in
The voltage control module 16 is electrically connected to the MVPT module 102 of the supplying power generation device 10A for generating a second duty cycle control signal 17 according to the output voltage Vo1 of the output supplying power. The second duty cycle control signal 17 adjusts the duty cycle of the MVPT module 102 to perform the MVPT process.
In an embodiment, similar to the power control module 14, the voltage control module 16 further includes an analog to digital converter 160, a control unit 162 and a power stage regulator unit 164. The analog to digital converter 160 converts the output voltage Vo1 from the analog form to the digital form. The control unit 162 controls the power stage regulator unit 164 to generate the second duty cycle control signal 17 according to the output voltage Vo1. In an embodiment, the control unit 162 determines a slope of a rate of voltage change of the output voltage Vo1 according an algorithm stored therein. The control unit 162 further determines that the output voltage Vo1 reaches the maximum output voltage when an absolute value of the slope is smaller than a predetermined threshold value of the rate of voltage change.
It is noted that the configuration of the voltage control module 16 illustrated in
The current switch 20 is operated to be electrically conducted or electrically unconducted according to the second duty cycle control signal 17. In an embodiment, the second duty cycle control signal 17 operates the current switch 20 to be electrically conducted during the high level and operates the current switch to be electrically unconducted during the low level, as illustrated in
The LC circuit 22 is electrically connected to the energy generation module 100 through the current switch 20. The LC circuit 22 in different supplying power generation devices 10A, 10B or 10C is either electrically connected to two of the neighboring supplying power generation devices (e.g. the LC circuit 22 in the supplying power generation devices 10B) or is either electrically connected to one of the neighboring supplying power generation devices and the MPPT module 12 (e.g. the LC circuits 22 in the supplying power generation devices 10A and 10C).
In an embodiment, the LC circuit 22 includes at least a capacitor 220 and an inductor 222 and selectively includes diodes 224 and 226 that provide a voltage-stabilizing mechanism. It is noted that the LC circuit 22 illustrated in
For example, when the duty cycle of the second duty cycle control signal 17 is 1, the second duty cycle control signal 17 is in the high state to keep operating the current switch 20 to be electrically conducted. When the duty cycle of the second duty cycle control signal 17 is 0.5, the second duty cycle control signal 17 is in the high state in half of a time period. The current switch 20 is operated to be electrically conducted in half of the time period accordingly. When the duty cycle of the second duty cycle control signal 17 is 0.25, the second duty cycle control signal 17 is in the high state in ¼ part of a time period. The current switch 20 is operated to be electrically conducted in ¼ part of the time period accordingly.
Therefore, by adjusting the durations of the electrically conducted state and the electrically unconducted state of the current switch 20 according to the second duty cycle control signal 17, the output current and the output voltage of the output supplying power are adjusted correspondingly. As described above, since the second duty cycle control signal 17 is generated according to the output voltage Vo1 of the output supplying power, the output voltage Vo1 is adjusted by the feedback mechanism and is adjusted to reach the maximum output voltage gradually. The MVPT process is therefore accomplished.
In an embodiment, the MPPT module 12 is implemented in a similar configuration as that of the MVPT module 102. The first duty cycle control signal 15 is gradually adjusted according to the feedback of the total output voltage Vdc and the total output current Idc such that the maximum output power is reached. The MPPT process is therefore accomplished.
In an embodiment, the MPPT process is performed first by the MPPT module 12 such that the total output supplying power having the maximum power is generated steadily by fixing the first duty cycle control signal 15 in the power generation control system 1. Subsequently, the MVPT process is performed by the MVPT module 102 to generate the output power having the maximum output voltage.
As illustrated in
As a result, the power generation control system 1 only tracks the maximum power of the total output supplying power and the maximum voltage of the output supplying power of each of the supplying power generation devices 10A, 10B and 10C. The monitoring of the voltages and currents of all the supplying power generation devices 10A, 10B and 10C is not necessary. Moreover, the complex design of the circuits to perform the tracking of the maximum power of all the supplying power generation devices 10A, 10B and 10C is not necessary. The power generation control system 1 maintains a steady output supplying power even if part of the supplying power generation devices 10A, 10B and 10C do not function normally.
The power generation control method 600 includes the steps outlined below. (The steps are not recited in the sequence in which the steps are performed. That is, unless the sequence of the steps is expressly indicated, the sequence of the steps is interchangeable, and all or part of the steps may be simultaneously, partially simultaneously, or sequentially performed).
In step 601, the MVPT module 102 in each of the supplying power generation devices 10A, 10B and 10C is controlled to receive an input power 11 generated from the energy generation module 100 to generate an output supplying power.
In step 602, the MPPT module 12 is controlled to generate the maximum supplying power 13 having a maximum power according to the total output supplying power generated from the supplying power generation devices 10A, 10B and 10C.
In step 603, the first duty cycle control signal 15 is generated according to the total output voltage Vdc and the total output current Idc of the total output supplying power to control the MPPT module 12 to perform a MPPT process on the total output supplying power.
In step 604, the second duty cycle control signal 17 is generated according to the output voltage Vo1 of the output supplying power of each of the supplying power generation devices 10A, 10B and 10C to control the MVPT module 102 to perform the MVPT process on the output supplying power.
When both of the MPPT process and the MVPT process are finished, the flow goes back to step 603 to perform the next tracking procedure. The maximum supplying power 13 generated by the power generation control system 1 is thus maintained at the maximum output power.
The MPPT process 700 can be used in the power control module 14 of the power generation control system 1 illustrated in
The MPPT process 700 includes the steps outlined below. (The steps are not recited in the sequence in which the steps are performed. That is, unless the sequence of the steps is expressly indicated, the sequence of the steps is interchangeable, and all or part of the steps may be simultaneously, partially simultaneously, or sequentially performed).
In step 701, the total output voltage Vdc and the total output current Idc of the total output supplying power are detected. The total output voltage Vdc is assigned to be a present output voltage Vnew and the total output current Idc is assigned to be a present output current Inew. Moreover, a present total output power Pnew is calculated.
The difference between the present total output power Pnew and a previous total output power Fold is calculated at the same time. The previous total output power Fold is calculated according to a previous total output voltage Vold and a previous total output current Iold. The calculated difference is served as the slope dP of the rate of power change of the total output power.
The difference between the present output current Inew and the previous total output current Iold is calculated at the same time. The calculated difference is served as the slope dI of the rate of current change of the total output current.
In step 702, whether the slope dP is larger than 0 is determined. When the slope dP is larger than 0, whether the slope dI is larger than 0 is determined in step 703.
When both of the slope dP and the slope dI are larger than 0, i.e. the condition 1 illustrated in
On the other hand, when the slope dP is determined to be smaller than 0 in step 702, whether the slope dI is larger than 9 is determined in step 706.
When the slope dP is smaller than 0 and the slope dI is larger than 0, i.e. the condition 3 illustrated in
When both of the slope dP and the slope dI are smaller than 0, i.e. the condition 4 illustrated in
When the adjustment of the slope dP is finished in steps 704, 705, 707 and 708, the present total output voltage Vnew is assigned to be the previous total output voltage Vold in step 709. Further, the present total output current Inew is assigned to be the previous total output current Iold, and the present total output power Pnew is assigned to be the previous total output power Pold.
Whether the slope dP is larger than a threshold value of the rate of power change is determined in step 710. When the slope dP is larger than the threshold value, the flow goes back to step 701 to detect the total output voltage Vdc and the total output current Idc to perform the adjustment since the maximum of the total output power is not tracked yet. When the slope dP is smaller than the threshold value, the total output power is close to the maximum before the adjustment. Therefore, the maximum of the total output power is substantially reached after the adjustment. The flow ends in step 711.
The MVPT process 900 can be used in the voltage control module 16 of the power generation control system 1 illustrated in
The MVPT process 900 includes the steps outlined below. (The steps are not recited in the sequence in which the steps are performed. That is, unless the sequence of the steps is expressly indicated, the sequence of the steps is interchangeable, and all or part of the steps may be simultaneously, partially simultaneously, or sequentially performed).
In step 901, the output voltage Vo1 of the output power is detected. The output voltage Vo1 is assigned to a present output voltage Vnewi. Further, a difference between the present output voltage Vnewi and a previous output voltage Voldi is calculated. The difference is served as a slope dVi of a rate of voltage change of the output voltage.
In step 902, whether a tendency of adjustment Si of the voltage is to decrease the voltage (Si=0) is determined. When the tendency of the adjustment Si is to decrease the voltage, whether the slope dVi is larger than 0 is determined in step 903.
When the tendency of the adjustment Si is to decrease the voltage and the slope dVi is larger than 0, the output voltage is decreased in step 904 and the tendency of the adjustment Si is kept to decrease the voltage.
When the tendency of the adjustment Si is to decrease the voltage and the slope dVi is smaller than 0, the output voltage is decreased in step 905 and the tendency of the adjustment Si is changed to increase the voltage (Si=1).
When the tendency of the adjustment Si is determined to increase the voltage in step 902, whether the slope dVi is larger than 0 is determined in step 906.
When the tendency of the adjustment Si is to increase the voltage and the slope dVi is larger than 0, the output voltage is increased in step 907 and the tendency of the adjustment Si is kept to increase the voltage.
When the tendency of the adjustment Si is to increase the voltage and the slope dVi is smaller than 0, the output voltage is decreased in step 908 and the tendency of the adjustment Si is changed to decrease the voltage.
When the adjustment of the slope dVi is finished in steps 904, 905, 907 and 908, the present output voltage Vnewi is assigned to be the previous output voltage Voldi in step 909.
Whether the slope dVi is larger than a threshold value of the rate of voltage change is determined in step 910. When the slope dVi is larger than the threshold value, the flow goes back to step 901 to detect the output voltage Vo1 to perform the adjustment since the maximum of the output voltage is not tracked yet. When the slope dVi is smaller than the threshold value, the output voltage is close to the maximum before the adjustment. Therefore, the maximum of the output voltage is substantially reached after the adjustment. The flow ends in step 911.
Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.
Number | Date | Country | Kind |
---|---|---|---|
102141708 | Nov 2013 | TW | national |