Hardware-in-the-Loop (HiL) Simulation of Singlephase 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 proposed 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 the grid-tied hybrid inverter is modeled 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 successfully mitigates the voltage level with a fast control response, while the grid-tied hybrid inverter's power factor can remain within the limit.