Non-unity Power Factor Operation of a Grid Connected Transformerless PV Inverter having Capability to Control Two Sub-arrays

This paper presents non-unity power factor operation of an existing grid connected transformerless PV inverter which can control two serially connected PV subarrays simultaneously. The proposed control strategy of the inverter is capable of exchanging real as well as reactive power with the grid. This enable the inverter to provide grid support which is in accordance with various grid code, e.g. IEEE 1547-2018, VDE-AR-N 4105, etc. In addition to this the other features of this inverter remain as it is, i.e. both the subarrays can be operated at their respective maximum power point when the subarrays face difference in the atmospheric conditions, i.e. insolation level and operating temperature. Dividing the PV array into two subarrays and control them in a simultaneous fashion enables higher power extraction from the PV array when the subarrays face difference in the atmospheric conditions. Due to the topological structure of the inverter, its leakage current remains within the limit mentioned in the standard, VDE 0126-1-1. The proposed control strategy is explained in details. The capability of the inverter to inject both the active and reactive power to the grid is verified through detailed simulation study in MATLAB SIMULINK platform.