Residential renewable energy distribution system with PQ control

In general, residential solar inverters can operate in either island or grid-tied mode. In grid-tied mode, the inverter can be operated based on either voltage control or current control. In this paper, a grid-connected current controlled inverter is presented. A stationary frame nonideal proportional resonant (PR) controller, in lieu of a conventional PI based controller, is applied to the outer current control loop to eliminate the steady-state error between the given reference and the inverter current output. The reference signal is directly given to satisfy the expected power output. The voltage source inverter (VSI) control system, reported in this paper, can estimate the instantaneous active and reactive power (PQ) based on a revised orthogonal signal generation (OSG) structure and control the power flow through a PQ controller in grid-connected mode. Thus, the solar inverter is able to work as a reactive power compensator, which helps lower transmission losses and improve grid power factor. Compared with traditional V/f based PQ controller and fuzzy-PQ controller, the proposed current based PQ controlled grid-tied inverter provides the system with faster reference tracking response and better power decoupling capability. Analysis and simulation results are presented in this paper to validate the proposed system.