Power Reserve Control of PV Grid-Tied Inverter With Transient Stability Constraint

To support the grid frequency, the power reserve control is adopted in the photovoltaic (PV) system without the energy storage. As an important part of the PV system, the influence of the DC-link voltage dynamics is ignored in the grid-tied inverter so that the PV source and grid-tied inverter cooperative control is rarely designed to enhance the transient stability. In this paper, the DC-link voltage dynamics are taken into consideration for the transient stability analysis of the grid-following (GFL) control and the grid-forming (GFM) control. It is found that the DC-link voltage dynamics deteriorate the transient stability of the GFL inverter and the GFM inverter. By analogy with the mass-spring-damper system, the enhanced controls are proposed with the equivalent elasticity for the GFL inverter and the GFM inverter. To support the grid frequency and enhance the transient stability, the frequency deviation feedback and equivalent elasticity cooperative control is proposed to regulate the active power of the PV source. Simulation tests are performed on a 10 kW grid-tied PV system and experimental tests are performed on a 1500 W grid-tied PV system, where the effectiveness of enhanced controls is verified.