Large-scale grid-connected photovoltaic power plants have many features of inverters and battery strings. For large-scale grid-connected photovoltaic power plants, how to measure the overall operating level of inverters and battery strings has always been a problem that plagues the industry. The discrete rate is a relative indicator reflecting the discreteness of measurement data. It is introduced by the photovoltaic intelligent information management system and is used for the first time to evaluate the overall operating level of inverters and strings. Discreteness, or dispersion factor, can be calculated from the ratio of the standard deviation of the acquired data to the average value. The photovoltaic intelligent information management system calculates the standard deviation and average value of the data collected every half hour during the statistical time (10:00-17:30), and then calculates the dispersion rate at the corresponding time point, and then weights the discrete rate at each time point. Calculate the average daily dispersion rate. The smaller the dispersion rate, the better the consistency of the overall operation of the equipment. Under normal circumstances, the discrete rate range is within 0~5%. If it exceeds this range, you need to find out the cause of the large dispersion rate of the equipment, eliminate the fault in time, and ensure the stable operation of the equipment. 1. Inverter AC power dispersion rate to evaluate inverter operation level Under the standard test conditions, the time series of AC output power of inverters with the same component capacity should be relatively consistent, but the AC output power between inverters is due to the performance difference of the inverter itself, the failure of the power generation unit equipment, weather conditions, and communication anomalies. There will be some differences. Therefore, introducing the AC power dispersion rate of the inverter to measure the degree of difference in the AC output power of the total station inverter, the smaller the dispersion rate, the more concentrated the time series curve of the output power between the inverters, and the more stable the overall operation of the inverter; If the dispersion rate is large, there are problems with individual inverters, and abnormal inverters need to be found. When calculating the discrete rate, the influence of weather factors on the discrete rate should be considered. For cloudy weather, you should check the operation of the inverter in the power station for a long period of time. Since the weather impact time is short, if the inverter dispersion rate continues to be large during the statistical period, the influence of the weather can be eliminated and the equipment failure or communication failure in the power station can be located. For inverters with low output power, you need to query the inverter to collect data. If the collected data shows that the communication is abnormal, the inverter with abnormal communication should be removed and the discrete power of the remaining inverters should be re-calculated to determine the operating condition of the inverter. If the discrete rate is within a reasonable range, it indicates that the communication problem is the main problem affecting the normal operation of the power station. Otherwise, the operation status of the power generating unit can continue to be viewed. It is analyzed whether the output power of the square array is small due to the failure of the power generating unit and affects the inverter. AC output power dispersion rate. For PV power plants with multiple inverter models, it is recommended to calculate the inverter discrete rate by model, which is determined by the nature of the inverter itself. 2. String current dispersion rate evaluation branch current operation level The concept of discrete rate is introduced into the string current, and the overall operating condition of all branches of the inverter is measured by the string current dispersion rate. The smaller the discrete rate, the more concentrated the time series curve of each branch current, and the more stable the power generation condition; Larger, it is considered that there is a problem with individual branches, quickly locate the battery string branch, and look for a branch with a current of 0 or less. When there are many branches under the inverter, the discrete rate index of all the branches under each combine box can be analyzed one by one to evaluate the overall running level of all the branches under the combiner box and accurately locate the current as 0 or low. Branch road. There are many reasons for the branch current to be 0 or the current is too low. For example, weeds are blocked, the junction box is burned, and the combiner box is burned. The operation and maintenance personnel should enter the site for troubleshooting according to the abnormal branch, and recalculate the troubleshooting. The string current dispersion rate, to determine whether the fault has been eliminated is the main reason leading to the large dispersion rate. (Guo Dan, Liu Jia, Ai Yingzhi, Ma Yue) Ball Valve,Pvc Ball Valve,Ball Check Valve,Threaded Ball Valve Haogong Valve Co Ltd , https://www.haogongvalve.com