This paper proposes a stationary reference frame current control algorithm for a single-phase grid-connected inverter (GCI) for improvement of transient dynamic performance. Disturbance, i.e., grid voltage in a target system, is estimated using a stator current observer, and the estimated disturbance is applied to a current controller for implementation of disturbance rejection control (DRC). In the proposed current control algorithm, the disturbance rejection control algorithm is applied to reduce the overcurrent occurring in the single-phase grid-connected inverter when grid faults happen. In this paper, the AC phase current of a single-phase inverter is controlled, instead of the current vector, which is a DC signal. To compensate for the drawbacks of controlling the AC phase current, such as phase lag and steady-state error, command feedforward control is also applied in the proposed control system. The proposed control algorithm is mathematically derived and represented in transfer functions and implemented via simulation and experiment.

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This paper presents a stationary reference frame grid current control algorithm for a grid-connected inverter (GCI) to improve command tracking performance and resilience in response to disturbances, i.e., a grid voltage incident in a GCI current control system. In the proposed algorithm, disturbance rejection is applied to reduce the overcurrent at the GCI in response to a grid fault. Disturbances to the GCI current control system are estimated using a grid current observer, and the estimate applied to the grid current controller to activate the disturbance rejection. The stationary reference frame current of a GCI system is also controlled to avoid cross-coupling issues at a synchronous reference frame model, reference transformation and dependency to phase locked loop (PLL) performance. However, the phase lead or lag and steady-state response error, which are drawbacks of AC signal control based on stationary reference frame proportional-integral (PI) controller, must be eliminated in order to secure competition with the synchronous reference PI (SRFPI) controller that was mainly used in the GCI system. Hence, to compensate for command tracking the AC current, such as steady-state response error and phase lead or lag, command feedforward control is applied in the proposed control system. The theory behind the proposed GCI current control algorithm is analyzed, and the proposed algorithm is tested via simulation and experimentation.

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