A Novel Photovoltaic Virtual Synchronous Generator Control Technology Without Energy Storage Systems

Abstract

Photovoltaic virtual synchronous generator (PV-VSG) technology, by way of simulating the external characteristics of a synchronous generator (SG), gives the PV energy integrated into the power grid through the power electronic equipment the characteristics of inertial response and active frequency response (FR)—this attracts much attention. Due to the high volatility and low adjustability of PV energy output, it does not have the characteristics of a prime mover (PM), so it must be equipped with energy storage systems (ESSs) in the DC or AC side to realize the PV-VSG technology. However, excessive reliance on ESSs will inevitably affect the application of VSG technology in practical PV power plants (PV-PPs). In view of this, this paper proposes the PV power reserve control type VSG (PV-PRC-VSG) control strategy. By reducing the active power output of part of the PV-PPs, the internal PV-PPs can maintain a part of the active power up/down-regulation ability in real time, instead of relying on external ESSs. By adjusting the active reserve power of this part, the output of the PV-PPs can be controlled within a certain range, and the PV-PPs can better simulate the PM characteristics and realize the FR of the grid by combining the VSG technology. At the same time, the factors affecting the reserve ratio are analyzed, and the position of the voltage operating point in PRC mode is deduced. Finally, the simulation results show that the proposed control strategy is effective and correct.

Keywords

• photovoltaic (PV)
• virtual synchronous generator (VSG)
• frequency response (FR)
• power reserve control (PRC)
• active power up-regulation