Hardware-in-the-Loop (HiL) Simulation of Single-phase Grid-tied Hybrid PV – Battery Inverter with Three-state Overvoltage Controller

This paper presents the overvoltage controller for a single-phase grid-tied hybrid inverter used in low-voltage distribution networks with photovoltaic (PV) and battery connections. The grid-tied hybrid PV – battery system can help with overvoltage control by drawing reactive power (Q) from the main grid and reducing active power (P) supplied to the main grid. The purposed overvoltage controller permits the grid-tied hybrid PV-battery inverter to operate in three states: 1) only Q absorption 2) absorbing Q with P curtailment through battery charging and 3) absorbing Q with P curtailment by limiting PV output. Additionally, the single-phase grid-tied hybrid inverter is controlled using an unbalanced synchronous reference frame technique with an extra voltage control loop based on P(V) and Q(V) droop controls. A hardware-in-the-loop (HiL) simulation is used for experimental validation. The power stage of grid-tied hybrid inverter is modelled in an OPAL-RT OP4510 HiL real-time simulator while the control stage is implemented on a TMS320F28379D Texas Instruments 32-bit DSP controller. The simulation results show that the single-phase grid-tied hybrid PV-battery inverter with the proposed overvoltage controller effectively mitigates overvoltage with a fast control response, while the grid-tied hybrid inverter’s power factor can remain within the limit.