A grid simulator with control of single-phase power converters in D-Q rotating frame

A control method in the direct-quadrature (DQ) rotating frame for a single-phase inverter or PFC rectifier is proposed to provide an infinite control gain (theoretically), thus zero steady state error at its fundamental frequency to achieve superior steady state and dynamic performance. This new control method transforms the physical "real circuit", in conjunction with an "imaginary orthogonal circuit", from the stationary frame to the DQ rotating frame so that the steady state voltage/current in the DQ frame become DC variables. The new control concept is validated through a single-phase grid simulator used for utility compatibility tests, as described in IEEE P1547 draft standard, IEEE Std 929, UL 1741 and NYSIR, for single-phase distributed generators (DG), such as residential fuel cell generators or photovoltaic power conditioning systems. Experimental results in steady state with programmable simulated utility line impedance are given along with the dynamic transient response for NYSIR type test. The control concept is also applicable to zero-sequence control for three-phase four-wire systems.