Voltage control of three-phase stand-alone photovoltaic system based on improved deadbeat controller

ABSTRACT Stand-alone photovoltaic systems (SAPs) based on three-phase inverters have found high attention, recently. However, unbalanced loading condition is inevitable condition for these inverters. To prepare a current flow for inevitable fourth wire current, four-leg inverter is a beneficial solution. To sinusoidal load voltage shaping, the control method is very important since it must maintain three-phase balanced sinusoidal load voltages. Among different linear and non-linear control methods, deadbeat (DB) method offers high simplicity as well as good accordance for digital implementation. But, it suffers from two sampling period delay which deteriorates the load voltage quality and sometimes results in instability of the control system. In this paper, new DB control method with delay compensation strategy is proposed which not only have the usual benefits of the DB control method but also it overcomes the aforementioned weakness. Finally, a 3 kW laboratory test bench based on DSP-based digital control board is provided to consider the result of the proposed control methods. Several tests under various inverter loads such as no load, full linear load and 100% unbalanced load are done to evaluate the benefits of the proposed system.