TWI499887B - Solar power system and abnormality detection method thereof - Google Patents

Description

Solar power generation system and its abnormality detection method

The invention relates to a solar power generation system and an abnormality detecting method thereof, in particular to a solar power generation system and an abnormality detecting method applicable to a maximum power point tracking technology.

In recent years, as the problem of environmental pollution has become more and more serious, many countries have begun to develop new green energy sources to reduce environmental pollution. Solar power systems convert solar energy into electrical energy, and this conversion does not produce any polluting substances, so solar power systems are gaining attention. The solar power generation system is composed of a plurality of solar power generation units. In order for the system to output maximum power, solar power systems typically require a maximum power point tracking algorithm to control the solar power unit.

According to the configuration of the solar power generation unit, the solar power generation system can be divided into a centralized system and a distributed system. The centralized system equipment is simple, but the technical difficulty of maximum power tracking is often caused by shading effect, power unit degradation or matching, and the maximum power output of this system will be lower than The sum of the maximum power output of each solar power unit also results in a reduction in system power generation efficiency. Therefore, the decentralized system becomes the alternative of another technology. The decentralized system uses the same maximum power point tracking technology as described above, but a power optimizer is connected in series with each solar power generation unit, so that each solar power generation unit performs maximum power point tracking of the module level; the disadvantage is that a large amount is added. The use of sensors and computing cores also contributes to the cost of system implementation. Although the decentralized system is aimed at the optimal output of each solar power generation unit, it is still necessary to perform voltage and current measurement at the power generation unit end, and maximum power calculation, which relatively increases the system construction cost.

In order to solve the above problems, a solar power generation system and an abnormality detecting method thereof are proposed, which can use the overall current and voltage output data of the system to modulate the maximum power output of the entire system at an optimum value, and also know each solar power generation in the system. The power generation situation of the unit, and whether the respective solar power generation units are reduced in power due to shading, deterioration, and damage.

One aspect of the present invention provides a solar power generation system and an abnormality detecting method thereof, which can maximize the maximum power output of the entire system, and determine whether the solar power generating unit occurs according to the duty cycle of the control signal received by the solar power generating unit. abnormal.

According to an embodiment of the invention, the solar power generation system includes a maximum power tracking controller and a complex array solar power generation unit. The maximum power tracking controller is electrically connected to the solar power generation unit to output a complex array control signal to the solar power generation unit, so that the solar power generation system outputs the most High Power. When the solar power unit outputs the maximum power, the maximum power tracking controller uses the plurality of duty cycle values of the control signal and the standard duty cycle range to determine whether at least one of the duty cycle values is within the standard responsibility period, when the duty cycle When at least one of the values is not within the corresponding standard responsibility period, the maximum power tracking controller determines that the solar power unit corresponding to at least one of the duty cycle values is abnormal.

According to another embodiment of the present invention, in the abnormality detecting method of the solar power generating system, a complex array solar power generating unit is first provided. Next, a standard duty cycle value establishment phase is performed to establish a standard duty cycle value corresponding to each solar power generation unit. In the standard duty cycle value establishment phase, the solar power generation unit is first checked to ensure that the solar power generation unit is normal. Then, the maximum power tracking controller is used to perform the maximum power tracking step, so that the solar power generation system outputs the maximum power, and obtains a plurality of historical control signals corresponding to the solar power generation unit. Then, when the solar power system outputs the maximum power, a plurality of historical duty cycle values of the historical control signals are calculated. Next, the duty cycle value corresponding to the solar power generation unit is recorded as a historical responsibility cycle, wherein each historical responsibility cycle value is defined as a standard duty cycle value of the corresponding solar power generation unit. Then, the standard duty cycle range of each solar power generation unit is calculated according to the standard duty cycle value of each solar power generation unit. In the power supply phase, the maximum power tracking controller is first used to perform a maximum power tracking step to output a plurality of control signals to the solar power generation unit to output maximum power to the solar power generation system, wherein the control signals are one-to-one corresponding to solar power generation. unit. Then, when the solar power system outputs the maximum power, Calculate the duty cycle value of each control signal. Then, it is judged whether the duty cycle value of one of the solar power generation units is within the corresponding standard responsibility period. When the duty cycle value of one of these solar power generation units is not within the standard duty cycle, an abnormality is determined in the solar power generation unit.

It can be seen from the above description that the solar power generation system and the abnormality detecting method of the embodiment of the present invention can understand the power generation situation of each solar power generation unit in the system according to the duty cycle of the control signal received by the solar power generation unit, and determine whether each solar power generation unit is caused by Shading, deterioration, damage, resulting in reduced power, but also provide sufficient information for managers to establish replacement, cleaning and other maintenance work, and achieve the desired power generation results when the system is installed.

100‧‧‧Solar power system

110‧‧‧MPPT controller

120‧‧‧Solar power unit

122‧‧‧DC/DC Converter

124‧‧‧Photovoltaic Module

130‧‧‧ Current Sensor

200‧‧‧Maximum power tracking method

210‧‧‧Measurement steps

220‧‧‧ Gradient calculation steps

230‧‧‧Maximum calculation steps

240‧‧‧Convergence judgment step

250‧‧‧ Recording steps

260‧‧‧current judgment step

300‧‧‧Anomaly detection method

310‧‧‧Standard duty cycle value establishment phase

312‧‧‧Checking steps

314‧‧‧Maximum power point tracking step

316‧‧‧ Calculation and record steps

318‧‧‧Standard responsibility cycle range calculation steps

320‧‧‧Power supply stage

322‧‧‧Maximum power point tracking step

324‧‧‧ Calculation steps

326‧‧‧ Judgment steps

V _load ‧‧‧ total voltage

I _load ‧‧‧ total current

D ₁ ~D _n ‧‧‧Responsibility cycle

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

1 is a schematic view showing the structure of a solar power generation system according to an embodiment of the present invention.

Figure 2 is a flow chart showing the maximum power tracking method performed by the Maximum Power Point Tracking controller.

FIG. 3 is a schematic flow chart showing an abnormality detecting method of a solar power generation system according to an embodiment of the present invention.

Please refer to FIG. 1 , which is a schematic diagram showing the architecture of a solar power generation system 100 according to an embodiment of the present invention. The solar power generation system 100 includes a Maximum Power Point Tracking controller 110, a plurality of solar power generation units 120, and a current sensor 130. In the present embodiment, each solar power generation unit 120 includes a DC/DC converter 122 and a photovoltaic module 124 (eg, a solar panel), but embodiments of the present invention are not limited thereto. The current sensor 130 is used to sense the magnitude of the total current I _load of the solar power generation system 100 and transmit it to the MPPT controller 110. The MPPT controller 110 is electrically connected to the current sensor 130 and the DC/DC converter 122 of each solar power generation unit 120 to output a control signal according to the total current I _loa d and the total voltage V _{load of the} solar power generation system 100 . To the DC/DC converter 122, thereby controlling the operating voltage of the solar power generating unit 120 and performing MPPT operation, wherein the control signal is a Pulse Width Modulation (PWM) signal, and the MPPT controller 110 adjusts the PWM signal. The duty cycle is used to perform MPPT operations. In this embodiment, the MPPT controller 110 sends control signals with duty cycles D ₁ ~ D _n to the DC/DC converter 122 of the solar power generation unit 120, respectively.

It should be noted that in the present embodiment, the total voltage V _load is a fixed value, so the solar power generation system 100 does not need to additionally install a voltage sensor to know the value of the total voltage V _load . However, in other embodiments of the invention, a voltage sensor can also be used to sense the value of the total voltage _Vload .

Please refer to FIG. 2, which is illustrated by the MPPT controller 110. A schematic diagram of the flow of the maximum power tracking method 200. In the present embodiment, the maximum power tracking method 200 performs maximum power tracking using the Steepest Ascent Method and the Golden Section, however, embodiments of the present invention are not limited thereto. Other methods, such as Particle Swarm Optimization (PSO), may be used in other embodiments of the invention to perform maximum power tracking of the solar power system 100.

In the maximum power tracking method 200, a measurement step 210 is first performed to add a duty cycle ΔD to the DC/DC converter 122 of the individual solar power generation unit 120, respectively, and then measure the amount of change in the total current I _load . The system consisting of n solar power generation units, including the current operating point, requires a total of n+1 points of data to be calculated to calculate the gradient. Next, a gradient calculation step 220 is performed. Taking a system composed of two solar power generation units as an example, the operation point x ^{(k) of} the kth iteration is defined as (D ₁ , D ₂ ). In addition to x ^(k) , it is also necessary to measure the objective function values under (D ₁ + ΔD , D ₂ ) and (D ₁ , D ₂ + ΔD ), and then calculate the gradient values by the following equation (1):

Where D ₁ and D ₂ are the initial duty cycles corresponding to the two solar power generation units, respectively, and the function f represents the relationship between the total current I _load (or total power) and the duty cycle.

Then, a maximum value calculation step 230 is performed to make a one-dimensional search using the golden section method along the gradient direction to find the maximum value in this direction. However, here you need to limit the search length so that too long a search length will increase unnecessary search time. On the other hand, as the number of iterations increases, the accuracy of the tracking can also be increased by narrowing the search length. Next, a convergence determination step 240 is performed to determine whether or not to converge using the following equation (2) as a convergence condition:

The value of the convergence threshold ε can be determined by the user according to the demand.

In the formula (2), the two adjacent search results f ^{( k )} and f ^{( k -1) are} compared, and the difference between the two is normalized by the previous output result, if the calculation result is smaller than the preset convergence threshold ε Then, it is judged that the MPPT converges, and this is the maximum power point. After finding the maximum power point, a recording step 250 is then performed to record the value of the total current I _load at the current maximum power. Then, a current determination step 260 is performed to measure subsequent current values during operation. If there is a significant change in the total current, the system condition changes, and then the maximum power tracking method 200 is re-executed from the current operating point. For example, the user can set a current change threshold and re-perform the maximum power tracking method 200 when the subsequent current value changes beyond the current change threshold.

It can be seen from the above description that the maximum power tracking method 200 of the present embodiment improves the lack of the existing distributed solar power system, and only needs a set of system voltage and current information to perform maximum power tracking of the solar power generation system, thereby greatly reducing solar power generation. The cost of the system is required to build the sensor.

Additionally, in solar power system 100, the optimal operational responsibility cycle for each DC/DC converter 122 is actually affected by the maximum power output of each solar power generation unit 120. It is assumed that the maximum power P _MPP,i of the i-th solar power generation unit 120 in the solar power generation system 10 is known, and it is known from the series system that the output currents of all the DC/DC converters 122 are equal if all the solar power generation units 120 are operating at the maximum. At the power point, the output voltage V _out,i of the DC/DC converter 122 of the i-th solar power generation unit 120 can be calculated by the following equation (3):

Wherein P _total is the total power output by the solar power generation system 100. Since all the solar power generation units 120 in a single system are placed at similar locations, the operating temperatures are not much different. Considering the change of the illuminance, the operating voltages of the solar panels V _{MPP, i} are similar, and the DC/DC converter 122 is at this time. The operational duty cycle D _{i is} directly affected by the maximum power value of the solar cell, and the operational responsibility cycle D _i can be expressed by the following formula (4):

Where κ = V _Load /V _MPP , where V _MPP is an approximation of V _MPP,i . Further, the above formula (4) is derived by using the DC/DC converter 122 as a step-down converter, but the DC/DC converter 122 of the embodiment of the present invention is not limited thereto.

After the shift, the last formula (5) is obtained.

It can be seen from the above formula (5) that when the solar power generation system 100 completes the maximum power point tracking, the solar power generation unit can be estimated by the above formula (5). The actual output power of 120 is further determined whether there is a situation in which the solar power generating unit 120 is occluded or malfunctioned.

Please refer to FIG. 3, which is a flow chart showing an abnormality detecting method 300 of a solar power generation system according to an embodiment of the present invention. The abnormality detecting method 300 determines whether or not the solar power generating unit 120 is abnormal by the operation duty cycle of the DC/DC converter 122. The anomaly detection method 300 includes a standard duty cycle value establishment phase 310 and a power supply phase 320. The standard duty cycle value establishing phase 310 is used to establish a standard duty cycle range for each solar power generating unit 120 so that the powering phase 320 can determine whether the solar power generating unit 120 is abnormal according to the standard duty cycle range.

In the standard duty cycle value establishment phase 310, an inspection step 312 is first performed to check all of the solar power generation units 120 to ensure that the solar power generation unit 120 is normal (unmasked or not faulty). Then, a maximum power point tracking step 314 is performed to utilize the maximum power tracking controller 110 for the maximum power tracking method to cause the maximum power tracking controller 110 to output control signals to all of the solar power generating units 120 to maximize the output of the solar power system 100. power. In the present embodiment, the maximum power point tracking step 314 utilizes the maximum power tracking method 200 to track the maximum power point, although embodiments of the invention are not so limited. In other embodiments of the invention, a particle swarm algorithm can also be utilized to track the maximum power point.

Then, a calculation and recording step 316 is performed to calculate a duty cycle value of the control signal received by each solar power generation unit 120 when the solar power generation system 100 outputs the maximum power, and record the duty cycle value as the corresponding solar power generation unit. The standard duty cycle value of 120. Then, carry out standard responsibility The period range calculation step 318 is to calculate a corresponding standard duty cycle range according to the standard duty cycle value corresponding to each solar power generation unit 120, such that each solar power generation unit 120 has a corresponding standard duty cycle range. In this embodiment, the standard duty cycle range is determined based on the standard duty cycle value and the preset tolerance range. For example, the user can set the preset tolerance range to ±5%, and the standard responsibility period range is ±5% of the standard duty cycle value.

In addition, since the standard duty cycle value establishment phase 310 is used to calculate the standard duty cycle range, the solar power unit control signal obtained in the standard responsibility cycle value establishment phase 310 is referred to as a history control signal, and the history control signal is responsible for the duty cycle. The value is referred to as the historical responsibility period value to distinguish between the control signal in the standard duty cycle value establishment phase 310 and the power supply phase 320 and its duty cycle value.

In the powering phase 320, a maximum power point tracking step 322 is first performed to continuously utilize the maximum power tracking controller 110 for the maximum power tracking method 200 to cause the maximum power tracking controller 110 to output control signals to all of the solar power generating units 120. The solar power generation system 100 is caused to output the maximum power. In an embodiment of the invention, the maximum power point tracking step 322 may be a continuation of the maximum power point tracking step 314. For example, when the power phase 320 is followed by the standard duty cycle value establishing phase 310, the maximum power point tracking can be continued with the maximum power tracking method 200 after the maximum power point tracking step 314 is implemented. However, embodiments of the invention are not limited thereto. In other embodiments of the invention, other steps may be inserted in the standard duty cycle value establishing phase 310 and the powering phase 320 to provide other beneficial functions.

Then, a calculation step 324 is performed to calculate a duty cycle value of the control signal received by each solar power generation unit 120 when the solar power generation system 100 outputs the maximum power. Next, a determining step 326 is performed to determine whether the duty cycle value of the control signal received by each solar power generating unit 120 is within a corresponding standard duty cycle range. If the duty cycle value of the control signal of a certain solar power generation unit 120 is not within the corresponding standard responsibility period, it is determined that the solar power generation unit 120 is abnormal (for example, faulty or blocked).

It can be seen from the above description that the abnormality detecting method 300 of the embodiment of the present invention can not only utilize the system current and voltage output data to modulate the maximum power output of the entire system at an optimal value, but also utilize the duty cycle value of each solar power generating unit to understand The power generation situation of each solar power generation unit in the system, and whether the respective solar power generation units are reduced in power due to shading, deterioration, and damage. As such, the abnormality detecting method 300 of the embodiment of the present invention can provide sufficient information for the manager to establish maintenance work such as replacement and cleaning, and achieve the power generation effect expected when the system is installed.

Additionally, it is worth mentioning that in other embodiments of the invention, the user can utilize the standard deviation of the duty cycle to establish a standard duty cycle range. Referring to the Table, its records based solar power generation unit 120 8 in the two kinds of illuminance conditions ^{(600W / m 2, 2 1000W} / m) generated two kinds of working example in (case 1, case 2), where D ₁ - D ₈ is the duty cycle value corresponding to the eight solar power generation units 120.

According to Table 1, it can be calculated that the average duty cycle corresponding to Case1 and Case2 is 40, and the standard deviation is 3.43 and 4.63, respectively. Next, use the standard deviation of the duty cycle to establish a standard range of liability cycles. For example, the average value of the duty cycle to 40 plus / minus standard deviation 3.43, can be obtained Case1 duty cycle corresponding to the standard range of 43.43-36.57, and a solar power generation unit determines the duty cycle D ₁ 120 corresponding to the occurrence of abnormality. As another example, the average value of the duty cycle to 40 plus / minus standard deviation 4.63, to obtain the corresponding standard of the duty cycle range of 44.63-35.37 Case2, and determines the duty cycle D ₁ and D ₂ corresponding to the solar power unit 120 An exception occurs.

Furthermore, in still another embodiment of the present invention, it is possible to determine whether the solar power generation unit is shielded or malfunctioned by the time when the solar power generation unit is determined to be abnormal. For example, in the case of the above-described Case1, if the time to fall outside the standard duty cycle D ₁ exceeds a preset range of the duty cycle of the time threshold, i.e. determines the duty cycle D ₁ corresponding to the solar power unit failure. Here, the time threshold is the sunshine time of the area where the solar power generation unit is located, but the embodiment of the present invention is not limited thereto. In other embodiments of the invention, the user can set the time threshold based on actual demand.

Although the present invention has been disclosed above in several embodiments, it is not intended to limit the invention, and is generally known in the technical field to which the present invention pertains. The scope of protection of the present invention is defined by the scope of the appended claims, and the scope of the invention is defined by the scope of the appended claims.

300‧‧‧Anomaly detection method

310‧‧‧Standard duty cycle value establishment phase

312‧‧‧Checking steps

314‧‧‧Maximum power point tracking step

316‧‧‧ Calculation and record steps

318‧‧‧Standard responsibility cycle range calculation steps

320‧‧‧Power supply stage

322‧‧‧Maximum power point tracking step

324‧‧‧ Calculation steps

326‧‧‧ Judgment steps

Claims (4)

A solar power generation system comprising: a complex array solar power generation unit; a maximum power tracking controller electrically connected to the solar power generation units to output a complex array control signal to the solar power generation units to maximize the output of the solar power generation system Power, wherein the control signals are pulse width modulation signals; and a current sensor for detecting a total current value output by the solar power generation units for the maximum power tracking controller to be based on the total current The value is used to calculate a total power value of the output of the solar power generation unit; wherein the maximum power tracking controller maximizes the output of the solar power generation system by a maximum gradient method (Steepest Ascent Method) and a Golden Section method (Golden Section) Power, and when the solar power system outputs maximum power, the maximum power tracking controller calculates a plurality of duty cycle values of the control signals and a plurality of standard duty cycle ranges corresponding to the solar power generating units, and determines the Whether at least one of the duty cycle values is located in the corresponding standard The maximum power tracking controller determines the solar power corresponding to the at least one of the duty cycle values when the at least one of the duty cycle values is not within the corresponding standard responsibility period An abnormality occurs in the unit. The standard duty cycle value range is calculated based on a standard duty cycle value and a predetermined tolerance range. The standard duty cycle value is a preset value. The solar power generation system of claim 1, wherein when at least one of the duty cycle values is not located in the corresponding standard duty cycle While in the enclosure, the maximum power tracking controller calculates that the at least one of the duty cycle values is not within an interval of the abnormal duration of the corresponding standard duty cycle, and determines whether the abnormal duration is greater than a preset time valve And determining, according to the determination result, that the solar power generation unit corresponding to the at least one of the duty cycle values is faulty or obscured. An abnormality detecting method for a solar power generation system, comprising: providing a complex array solar power generating unit; providing a current sensor to detect a total current value outputted by the solar power generating units, for a maximum power tracking controller according to the total Calculating a total power of the output of the solar power generating units; performing a standard duty cycle value establishing phase, comprising: checking the solar power generating units to ensure that the solar power generating units are normal; using the maximum power tracking controller And performing a maximum power tracking step, so that the solar power system outputs maximum power, and obtains a plurality of historical control signals corresponding to the solar power generating units, wherein the historical control signals are pulse width modulation signals, and the maximum power The tracking controller performs the maximum power tracking step by using the Steepest Ascent Method and the Golden Section; when the solar power system outputs the maximum power, calculating a plurality of historical responsibilities of the historical control signals Period value; record the solar power generation The historical responsibility period values corresponding to the units, wherein each of the historical responsibility period values is defined as a standard duty cycle value of the corresponding solar power generation unit; Calculating a standard responsibility period range of each of the solar power generation units according to a standard duty cycle value of each of the solar power generation units, wherein the standard responsibility period range is based on the standard responsibility period value and a predetermined tolerance range Determining; and performing a power supply phase, comprising: using the maximum power tracking controller to perform the maximum power tracking step to output a plurality of control signals to the solar power generating units to output maximum power to the solar power generation system, wherein the The control signals are one-to-one corresponding to the solar power generating units, and the control signals are pulse width modulation signals; and when the solar power system outputs maximum power, calculating a duty cycle value of each of the control signals; Determining whether the duty cycle value of one of the solar power generation units is within a corresponding standard duty cycle period; and when the duty cycle value of one of the solar power generation units is not within the standard responsibility cycle period, It is decided that the person of the solar power generation units is abnormal. The method for detecting an abnormality of the solar power generation system according to Item 3 of the claim further includes: when the responsibility period value of one of the solar power generation units is not within the standard responsibility period, calculating the responsibility period value is not An abnormal duration in the range of the standard responsibility period; and determining whether the abnormal duration is greater than a preset time threshold to obtain a determination result; wherein, when the determination result is yes, determining the solar power generation units The person fails, and when the result of the determination is no, it is determined that the person of the solar power generation units is shielded.