Photovoltaic Module Current Mismatch Fault Diagnosis Based on I-V Data

Frequent faults of photovoltaic (PV) modules will affect the power generation efficiency and service life of the system. In particular, PV module current mismatch faults will cause the output current of the module to decrease, and the I-V curve will have a step, which will seriously affect the output power and even cause a series of safety problems. This article focuses on the current mismatched fault, that is, partial shadow, hot spot, and cell cracks. Through field investigation, faulty PV modules in multiple PV power plants are collected, the I-V characteristics of a large number of faulty PV modules are tested, and the fault characteristics of different fault type modules are first extracted. A novel fault diagnosis method based on I-V data is then proposed. This method determines the step and inflection point of the I-V curve by detecting the concave and convexity of the I-V data. The fault characteristic value is further amplified by the Exp-exponential function. In order to further confirm the specific fault, according to the characteristics of the step, the combination of the slope of the step segment is used to decouple shadow, hot spot, and cell cracks faults. The experimental verifications from the actual PV power plant are demonstrated to show the effectiveness of the proposed fault diagnosis method for the above faults.