| As the complicated structure of the PV generation systems and variety of application environments, the mismatch and hot spot phenomena caused by partial shading or non-uniform illumination not only heavily affect the output characteristics of photovoltaic arrays, but also create safety and reliability problems. The P-U curve of PV arrays will have the characteristics of multi-summit under partial shading, not only a serious decline in global peak power, and the local peak power also caused a great disturbance. At present, change the structure of PV generation systems into multi-string systems, but this approach cause lower reliability, the structure of the whole system change complex, increases the cost. Second, the application of global peaks for MPPT algorithm in the centralized PV generation systems, but it is complex to implement in hardware and the controller needs high speed and high precision.The output power of PV arrays is mainly affected by the irradiance. This paper proposes a reconfiguration method. PV arrays change the interconnection in order to change the distribution of the shadow, thus improving the output characteristics of PV arrays, to reduce the impact on the irradiance under partial shading, to reduce the decline in global peak power.For local reconfiguration method in PV arrays, this paper uses shading degree model to represent the size of decline in the irradiance of each submodule. TCT PV array is divided into a fixed solar array and an adaptive bank, and proposes the shading degree model-based fuzzy control reconfiguration algorithm. According to the shading degree of the submodules, the expert system summarizes the fuzzy rules. The number of modules to compensate is determined by the fuzzy inference. Using a switching matrix to change the connection of the adaptive bank and the fixed part of a PV array, the loss of the output power is reduced.In order to verify the validity of algorithm, the hardware circuit of the control system with partial shading condition is constructed. The experimental results show when the partial shade phenomenon occurs, the system can quickly respond to the changes of external environments. |
