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Several methods to solve the failure of PV combiner box

38 Published by admin 6月 01,2020

As the most commonly used equipment in PV power plants, PV combiner boxes are usually prone to various failures. Operation and maintenance personnel need to check the fault point through inspection. Taking a 20MW power plant as an example, the traditional pure manual inspection method basically takes a month to patrol the PV combiner box of the power plant. The appearance of the view takes up most of the workload, and checking the internal combiner box is a sampling method. It is difficult to conduct an in-depth investigation. The only way to find the fault is to control the current value of the system, but the actual situation is that the waiter will only check the solar inverter. For the PV combiner box, the data of the power generation status of the device at the level of the PV combiner box is large and unintuitive, and it is difficult for management personnel to locate and track the faulty device.

pv combiner box

The big data monitoring plan is to carry out daily diagnosis of each PV combiner box of the entire station, give the daily fault diagnosis results of each PV combiner box, understand the operation status of PV combiner box-level equipment at a glance, and instruct personnel to carry out Targeted inspection. Check and investigate, supervise the personnel in the station to recover the faulty equipment, make necessary improvements to find and repair the fault, so that the fault is no longer unattended. In terms of power station results, compared to traditional inspection methods, the method of monitoring big data solutions can increase the timeliness of fault detection by 90% and the time to failure by 70%. Lifting point: compare the operating status of the PV combiner box, check the power generation status of the light string, and check the position of the faulty light string.

pv combiner box
Steps to improve efficiency:
Step 1: data cleaning:
Set a certain branch current threshold, delete data above or below this value during communication, and delete abnormal data and the same value as the branch current at adjacent times to generate a large negative during the communication value. Filter out with large positive values ​​and retain valuable data for the next step.

Step 2: branch selection;
According to the actual number of branch groups accessed by the device, select the actual number of string current values, calculate the sum of the current values ​​of each branch within a period, sort from small to large, and take the first 12 channels (the combiner returns 16 times each time) Branch current value, but only 12 channels are actually connected) The branch that has the largest sum of character string current values ​​is used as the branch that actually accesses the device, and the standard deviation between the branches is calculated again for each current value for filtering.

pv combiner box

Step 3: Calculate the weighted discrete rate;
After the above screening and each data of each branch, the standard deviation and average value of the branch current at each moment are calculated, and the average value of the branch current at each moment is used as the weight to calculate the weight. The average value of the variance coefficient of the branch current at each moment.

The fourth step: early warning. Through the above calculation and screening, a constant value can be obtained, and the branch current value of the PV combiner box can be compared with it to determine whether the PV combiner box is faulty.

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