CN105515531B - A kind of photovoltaic module decay abnormality diagnostic method based on monitoring system - Google Patents

Abstract

The invention discloses a method for diagnosing abnormal attenuation of photovoltaic modules based on a monitoring system, which includes: Step 1, establishing a corresponding power generation equipment model according to the topological structure of a photovoltaic power station; Step 2, dividing the virtual diagnosis area of the power generation equipment model; Step 3 , collect the equivalent current value of each photovoltaic combiner box branch; Step 4, determine the abnormal photovoltaic combiner box branch; Step 5, determine whether the abnormality of the combiner box branch is related to the attenuation of the photovoltaic module; Step 6, determine the photovoltaic module with abnormal attenuation string. The present invention diagnoses the abnormal combiner box branch caused by the attenuation of the photovoltaic module by logically analyzing the real-time operation data of each branch current of the photovoltaic combiner box collected by the monitoring system, and further analyzes and locates the photovoltaic module group associated with the abnormal branch It can avoid the operating condition that the photovoltaic module does not have the function of communication and interaction, so that the local fault point is not easy to be found for a long time, which leads to the reduction of the power generation efficiency of the photovoltaic power station.

Description

A monitoring system-based diagnosis method for abnormal attenuation of photovoltaic modules

technical field

The invention relates to the technical field of green energy power generation, in particular to a method for diagnosing abnormal attenuation of photovoltaic modules based on a monitoring system.

Background technique

As the energy crisis is approaching, new energy has become one of the main energy sources in the world in the future. Photovoltaic power generation, as a new green energy industry, has gradually gained the attention and support of the country. However, due to the huge number of photovoltaic modules in photovoltaic power plants, the high failure rate of photovoltaic power generation panels caused by internal and external factors, and the lack of communication and interaction capabilities of photovoltaic modules, etc., resulting in a decrease in the photoelectric conversion rate of photovoltaic power generation, and also caused It reduces the increase of operation and maintenance cost and the waste of power resources.

With the continuous development of computer technology, the application of big data mining technology will improve the operation and maintenance level of photovoltaic power plants.

Contents of the invention

The technical problem to be solved by the present invention is: based on the real-time monitoring technology, diagnose the abnormal attenuation of the photovoltaic module in operation, find the fault point in time, ensure the normal operation of the photovoltaic power station, and improve the power generation efficiency of the photovoltaic power station.

The technical solution adopted by the present invention is specifically: a method for diagnosing abnormal attenuation of photovoltaic modules based on a monitoring system, the monitoring system controls and monitors the operating status and electrical quantity of power generation equipment in a photovoltaic power station in real time;

The method includes the following steps,

Step 1, establishing a photovoltaic power station power generation equipment model based on the topological structure of the photovoltaic power station power generation equipment;

The topological structure of the above-mentioned photovoltaic power station power generation equipment includes more than one photovoltaic inverter cell, and each photovoltaic inverter cell is equipped with more than one photovoltaic inverter, and each photovoltaic inverter is connected to more than one photovoltaic combiner box. The combiner box includes more than one branch of the combiner box, and each branch of the combiner box is connected in series with more than one photovoltaic module;

Step 2, according to the geographical area where the photovoltaic modules are located in the photovoltaic power station, group the photovoltaic combiner boxes associated with them, and virtualize the photovoltaic power station to include several virtual diagnostic areas;

Step 3: Collect the current value of each photovoltaic combiner box branch in the photovoltaic power station in real time, the voltage value of the positive busbar of the inverter DC cabinet to the ground, and the voltage value of the negative busbar to ground, and convert the current value of each combiner box branch into equal Effective current value;

Step 4: Using each virtual diagnosis area set in step 2 as a unit, diagnose whether each photovoltaic combiner box branch in each virtual diagnosis area is abnormal, if yes, go to step 5, otherwise end this diagnosis;

The above diagnosis of whether the branches of each photovoltaic combiner box are abnormal includes the following steps:

a1, define the diagnosis time interval, whether the diagnosis time is within the diagnosis time interval;

b1, define the diagnostic effective radiation threshold, use the light irradiation instrument to detect the current optical radiation value of each virtual diagnostic area, and diagnose whether the current radiation value is greater than the diagnostic effective radiation threshold;

c1, on the basis that the diagnosis results of a1 and b1 are both yes, calculate the average value of the equivalent current of the combiner box branch in each virtual diagnosis area, and define the first equivalent current threshold according to the calculation result; detect the corresponding virtual diagnosis area If the detection value is lower than the first equivalent current threshold, the corresponding photovoltaic combiner box branch is diagnosed as abnormal;

d1, on the basis that the diagnosis results of a1 and b1 are both yes, combined with the current light radiation value and photovoltaic panel parameters, theoretically calculate the equivalent current value of each combiner box branch in each virtual diagnosis area, and define according to the theoretical calculation results The second equivalent current threshold: detect the actual equivalent current of each combiner box branch in each virtual diagnosis area, if the actual equivalent current is lower than the second equivalent current threshold, then diagnose the corresponding photovoltaic combiner box branch as abnormal;

Step 5. Diagnose whether the abnormal condition of the branch of the combiner box is related to the attenuation of the photovoltaic module. If so, go to step 6. Otherwise, end this diagnosis;

The diagnostic conditions related to the abnormal working condition of the branch circuit of the combiner box and the attenuation of photovoltaic modules include:

a2, the equivalent current of the photovoltaic combiner box branch is non-zero or non-close to zero;

b2, the difference between the absolute value of the positive busbar-to-ground voltage of the photovoltaic inverter DC cabinet and the negative busbar-to-ground voltage is zero or close to zero;

Step 6: Use the photovoltaic power plant power generation equipment model defined in step 1 to locate the photovoltaic module string associated with the abnormal combiner box branch. The photovoltaic module string includes photovoltaic modules with attenuation abnormal operating conditions.

When the present invention is applied, the relevant diagnosis of the photovoltaic modules in the photovoltaic power station can be completed by the monitoring system, and the photovoltaic modules with abnormal attenuation conditions can be analyzed based on the relevant operating state data obtained by the monitoring system, so that it is convenient for the staff to maintain in time and guarantee Normal operation of photovoltaic power plants.

Further, the present invention also includes step 7, which defines a repeated diagnosis time interval, repeats step 3 to step 6 at each time interval, and if the same photovoltaic combiner box branch is diagnosed as abnormal for 4 consecutive times due to photovoltaic module attenuation, output Alarm information, the alarm information includes the photovoltaic module string information located in step 6;

If the diagnosis result of step 4 or step 5 is no, go to step 7. The photovoltaic module string information includes a topology link path corresponding to each photovoltaic module in the string, so that it is convenient for operation and maintenance personnel to perform inspection and maintenance in a timely manner. The repeated diagnosis time interval can be set to half an hour, and the monitoring system collects the electrical quantity of each photovoltaic combiner box branch in the topological structure every half hour, and then diagnoses.

If it is necessary to exit the diagnosis process due to other reasons after step 7, the method of the present invention is ended, otherwise, continue to repeat steps 3 to 7.

Preferably, in Step 4 of the present invention, the diagnostic time interval is between 9 am and 3 pm; the diagnostic effective radiation threshold is 400W/m ² ; the first equivalent current threshold is the average equivalent current in the corresponding virtual area 70% of the value; the second equivalent current threshold is 60% of the theoretically calculated value of the theoretical equivalent current of the corresponding combiner box branch.

The beneficial effect of the present invention is: by logically analyzing the real-time operation data of each branch current of the photovoltaic combiner box collected by the monitoring system, the abnormal combiner box branch is diagnosed, and further analysis is made if the abnormality of the combiner box branch is related to the attenuation of the photovoltaic module , the photovoltaic module string associated with the abnormal branch is located through the photovoltaic power station data model, and an alarm is issued. The invention can avoid the operation condition that the photovoltaic module does not have the communication interaction function, so that the local fault point is not easy to be found for a long time, which leads to the reduction of the power generation efficiency of the photovoltaic power station; at the same time, the invention does not need to add a professional fault diagnosis device in the photovoltaic power station. also decreased accordingly.

Description of drawings

Figure 1 shows a schematic flow chart of the method of the present invention.

detailed description

As shown in FIG. 1 , the present invention is a method for diagnosing abnormal attenuation of photovoltaic modules based on a monitoring system. The monitoring system controls and monitors the operating status and electrical quantity of power generation equipment in a photovoltaic power station in real time;

The inventive method comprises the following steps,

Step 1, establishing a photovoltaic power station power generation equipment model based on the topological structure of the photovoltaic power station power generation equipment;

The electrical connection structure of photovoltaic power generation equipment is a topological structure. The topology structure is as follows: multiple photovoltaic inverter cells are set in one photovoltaic power station, multiple photovoltaic inverters are set in one photovoltaic inverter cell, and one photovoltaic inverter Connect multiple photovoltaic combiner boxes, one photovoltaic combiner box has multiple combiner box branches, and one combiner box branch connects multiple photovoltaic modules in series;

Step 2, according to the geographical area where the photovoltaic modules are located in the photovoltaic power station, group the photovoltaic combiner boxes associated with them, and virtualize the photovoltaic power station to include several virtual diagnostic areas;

Step 3: Collect the current value of each photovoltaic combiner box branch in the photovoltaic power station in real time, the voltage value of the positive busbar of the inverter DC cabinet to the ground, and the voltage value of the negative busbar to ground, and convert the current value of each combiner box branch into equal Effective current value;

Step 4: Using each virtual diagnosis area set in step 2 as a unit, diagnose whether each photovoltaic combiner box branch in each virtual diagnosis area is abnormal, if yes, go to step 5, otherwise end this diagnosis;

The above diagnosis of whether the branches of each photovoltaic combiner box are abnormal includes the following steps:

a1, define the diagnosis time interval, whether the diagnosis time is within the diagnosis time interval;

b1, define the diagnostic effective radiation threshold, use the light irradiation instrument to detect the current optical radiation value of each virtual diagnostic area, and diagnose whether the current radiation value is greater than the diagnostic effective radiation threshold;

c1, on the basis that the diagnosis results of a1 and b1 are both yes, calculate the average value of the equivalent current of the combiner box branch in each virtual diagnosis area, and define the first equivalent current threshold according to the calculation result; detect the corresponding virtual diagnosis area If the detection value is lower than the first equivalent current threshold, the corresponding photovoltaic combiner box branch is diagnosed as abnormal;

d1, on the basis that the diagnosis results of a1 and b1 are both yes, combined with the current light radiation value and photovoltaic panel parameters, theoretically calculate the equivalent current value of each combiner box branch in each virtual diagnosis area, and define according to the theoretical calculation results The second equivalent current threshold: detect the actual equivalent current of each combiner box branch in each virtual diagnosis area, if the actual equivalent current is lower than the second equivalent current threshold, then diagnose the corresponding photovoltaic combiner box branch as abnormal;

Step 5. Diagnose whether the abnormal condition of the branch of the combiner box is related to the attenuation of the photovoltaic module. If so, go to step 6. Otherwise, end this diagnosis;

The diagnostic conditions related to the abnormal working condition of the branch circuit of the combiner box and the attenuation of photovoltaic modules include:

a2, the equivalent current of the photovoltaic combiner box branch is non-zero or non-close to zero;

b2. The difference between the absolute value of the positive busbar-to-ground voltage of the photovoltaic inverter DC cabinet and the negative busbar-to-ground voltage is zero or close to zero.

Example

The embodiment shown in Figure 1 also includes step 7, which defines the time interval for repeated diagnosis, and repeats steps 3 to 6 at each time interval. If the same photovoltaic combiner box branch is diagnosed as abnormal for 4 consecutive times due to photovoltaic module attenuation , the alarm information is output, and the alarm information includes the PV module string information located in step 6;

If the diagnosis result of step 4 or step 5 is no, go to step 7. The photovoltaic module string information includes a topological link path corresponding to each photovoltaic module in the string, so that it is convenient for operation and maintenance personnel to perform timely inspection and maintenance. The repeated diagnosis time interval can be set to half an hour, and the monitoring system collects the electrical quantity of each photovoltaic combiner box branch in the topological structure every half hour, and then diagnoses.

If it is necessary to exit the diagnosis process due to other reasons after step 7, the method of the present invention is ended, otherwise, continue to repeat steps 3 to 7.

When this embodiment is applied, the data model corresponding to the topology established in step 1 is as follows:

In the data model, the photovoltaic power station contains multiple photovoltaic inverter cells, which are respectively recorded as photovoltaic inverter cell 1, photovoltaic inverter cell 2, ..., photovoltaic inverter cell n;

The photovoltaic inverter cell contains multiple photovoltaic inverters, which are respectively recorded as photovoltaic inverter 1, photovoltaic inverter 2, ..., photovoltaic inverter n;

A photovoltaic inverter is connected to multiple combiner boxes. For example, the combiner boxes connected to photovoltaic inverter 1 are respectively recorded as combiner box 1-1, combiner box 1-2, ..., combiner box 1-n;

Multiple combiner box branches are connected in parallel in one photovoltaic combiner box. Road 1-1-n;

A combiner box branch is connected in series with multiple photovoltaic power generation components. For example, the photovoltaic modules connected in series with branch x are: photovoltaic module x-1, photovoltaic module x-2, ..., photovoltaic module x-n.

The setting of step 2 is because the photovoltaic modules in the photovoltaic power station are widely distributed in the photovoltaic power station, so the setting rule of the virtual diagnosis area is that the combiner boxes associated with the photovoltaic modules with similar external environments are the same analysis and comparison area, which is conducive to improving diagnostic accuracy. Therefore, in this embodiment, the photovoltaic power plant is divided into virtual area 1, virtual area 2, . . . , virtual area n according to the actual engineering geographical distribution.

The reason why step 3 converts the sampled PV combiner box branch current value into an equivalent current when doing the abnormal judgment processing is that the photovoltaic modules connected in series in each photovoltaic combiner box branch have inconsistencies in the number of connections and output power The difference, after equivalence, the influence of this difference can be avoided. And after the photovoltaic module is updated due to failure, the equivalent current coefficient of the photovoltaic combiner box branch associated with the replacement board needs to be updated in time to ensure the reliability of the diagnosis.

When performing step 4, the diagnostic time interval can be defined as between 9 am and 3 pm; the diagnostic effective radiation threshold is 400W/m2; the first equivalent current threshold is 70% of the average value of the equivalent current in the corresponding virtual area ; The second equivalent current threshold is 60% of the theoretically calculated value of the corresponding combiner box branch. When performing diagnosis in steps c1 and d1, the diagnosis result is valid only if the time interval and light radiation value are within the range defined by a1 and b1. During the d1 diagnosis, the theoretical equivalent current is calculated according to the light radiation value and the actual photovoltaic panel parameters, which is an existing technology. The photovoltaic panel parameters include the number of panels, specifications and other parameters.

Further, through steps five and six, the photovoltaic module strings associated with the abnormal confluence branch are obtained.

For example, if it is diagnosed that there is an abnormality in the photovoltaic combiner box branch 1 in the virtual area 1, the photovoltaic module x-1 and photovoltaic module x -2, ..., photovoltaic modules x-n, there may be operating conditions with abnormal attenuation in these photovoltaic modules.

Then output an alarm after multiple diagnoses in step 7, which is convenient for operation and maintenance personnel to check.

If it is necessary to exit the diagnosis process due to other reasons after step 7, the method of the present invention is ended, otherwise, continue to repeat steps 3 to 7.

The present invention diagnoses the abnormal combiner box branch by logically analyzing the real-time operation data of each branch current of the photovoltaic combiner box collected by the monitoring system, and further analyzes that if the abnormality of the combiner box branch is related to the attenuation of the photovoltaic module, the photovoltaic power station The data model locates the photovoltaic module string associated with the abnormal branch and sends an alarm. The invention can avoid the operation condition that the photovoltaic module does not have the communication interaction function, so that the local fault point is not easy to be found for a long time, which leads to the lower power generation efficiency of the photovoltaic power station; at the same time, the invention does not need to add a professional fault diagnosis device in the photovoltaic power station, and the also decreased accordingly.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and modifications can also be made. It should also be regarded as the protection scope of the present invention.

Claims (3)

1. A method for diagnosing anomalous attenuation of photovoltaic modules based on a monitoring system, the monitoring system controls and monitors the operational state and electrical quantity of the generating equipment in the photovoltaic power station in real time; it is characterized in that: The method includes the following steps, Step 1, establishing a photovoltaic power station power generation equipment model based on the topological structure of the photovoltaic power station power generation equipment; The topological structure of the above-mentioned photovoltaic power station power generation equipment includes more than one photovoltaic inverter cell, and each photovoltaic inverter cell is equipped with more than one photovoltaic inverter, and each photovoltaic inverter is connected to more than one photovoltaic combiner box. The combiner box includes more than one branch of the combiner box, and each branch of the combiner box is connected in series with more than one photovoltaic module; Step 2, according to the geographical area where the photovoltaic modules are located in the photovoltaic power station, group the photovoltaic combiner boxes associated with them, and virtualize the photovoltaic power station to include several virtual diagnostic areas; Step 3: Collect the current value of each photovoltaic combiner box branch in the photovoltaic power station in real time, the voltage value of the positive busbar of the inverter DC cabinet to the ground, and the voltage value of the negative busbar to ground, and convert the current value of each combiner box branch into equal Effective current value; Step 4: Using each virtual diagnosis area set in step 2 as a unit, diagnose whether each photovoltaic combiner box branch in each virtual diagnosis area is abnormal, if yes, go to step 5, otherwise end this diagnosis; The above diagnosis of whether the branches of each photovoltaic combiner box are abnormal includes the following steps: a1, define the diagnosis time interval, whether the diagnosis time is within the diagnosis time interval; b1, define the diagnostic effective radiation threshold, use the light irradiation instrument to detect the current optical radiation value of each virtual diagnostic area, and diagnose whether the current radiation value is greater than the diagnostic effective radiation threshold; c1, on the basis that the diagnosis results of a1 and b1 are both yes, calculate the average value of the equivalent current of the combiner box branch in each virtual diagnosis area, and define the first equivalent current threshold according to the calculation result; detect the corresponding virtual diagnosis area If the detection value is lower than the first equivalent current threshold, the corresponding photovoltaic combiner box branch is diagnosed as abnormal; d1, on the basis that the diagnosis results of a1 and b1 are both yes, combined with the current light radiation value and photovoltaic panel parameters, theoretically calculate the equivalent current value of each combiner box branch in each virtual diagnosis area, and define according to the theoretical calculation results The second equivalent current threshold: detect the actual equivalent current of each combiner box branch in each virtual diagnosis area, if the actual equivalent current is lower than the second equivalent current threshold, then diagnose the corresponding photovoltaic combiner box branch as abnormal; After the diagnosis in step c1 and step d1, the photovoltaic combiner box branch that is diagnosed as abnormal in any of the two steps is the abnormal photovoltaic combiner box branch; Step 5. Diagnose whether the abnormal condition of the branch of the combiner box is related to the attenuation of the photovoltaic module. If so, go to step 6. Otherwise, end this diagnosis; The diagnostic conditions related to the abnormal working condition of the branch circuit of the combiner box and the attenuation of photovoltaic modules include: a2, the equivalent current of the photovoltaic combiner box branch is non-zero or non-close to zero; b2, the difference between the absolute value of the positive busbar-to-ground voltage of the photovoltaic inverter DC cabinet and the negative busbar-to-ground voltage is zero or close to zero; Step 6: Use the photovoltaic power plant power generation equipment model defined in step 1 to locate the photovoltaic module string associated with the abnormal combiner box branch. The photovoltaic module string includes photovoltaic modules with attenuation abnormal operating conditions. 2. The method for diagnosing abnormal attenuation of photovoltaic modules based on a monitoring system according to claim 1, further comprising step 7, defining a time interval for repeated diagnosis, and performing step 3 to step 6 repeatedly at each time interval, if there is the same If the photovoltaic combiner box branch is diagnosed as abnormal for four consecutive times due to the attenuation of photovoltaic modules, an alarm message will be output. The alarm information includes the information of the photovoltaic module string located in step 6; If the diagnosis result of step 4 or step 5 is no, go to step 7. 3. The method for diagnosing abnormal attenuation of photovoltaic modules based on a monitoring system according to claim 1 or 2, wherein in step 4, the diagnosis time interval is between 9 am and 3 pm; the diagnostic effective radiation threshold is 400W /m ² ; the first equivalent current threshold is 70% of the average value of the equivalent current in the corresponding virtual area; the second equivalent current threshold is 60% of the theoretically calculated value of the equivalent current of the branch of the corresponding combiner box.