Determination of maximum solar power under shading and converter faults—A prerequisite for failure-tolerant power management systems

Abstract

According to the fact that the performance of power management systems depends on generation forecasts, a scheme is proposed to detect the shading fault and the converter failure in a PV system and determine the maximum available solar power in the presence of these faults. Since the MPP of a PV array under uniform and partial shading faults is smaller than that of non-shading condition, for MPP tracking operations, difference between acquired and estimated power is an indicator for the shading fault. However, when the load power is small enough to be satisfied by the shaded PV array, the defined voltage ratio is used to detect the shading fault. In the case of shading fault, maximum available solar power is determined based on the output power of the PV system. Converter failure, which is modeled as the switch stuck-open fault or the switch stuck-on fault, is also considered in this paper. It is shown that under the switch stuck-open fault, the output power of the PV system will be zero; while, under the switch stuck-on fault, the output power shows a sinusoidal behavior. Based on the PV system power analysis, a procedure is also proposed to detect the converter failure and determine the maximum available solar power under this fault.