Grid Inertia Based Frequency Regulation Strategy of Photovoltaic System Without Energy Storage

Generic synthetic inertia scheme for voltage source inverters

“…This paper proposes a generic synthetic inertia (GSI) scheme that can be readily applied in any voltage source inverter (VSI) DC link of renewable power generations (RPG), with the following features: 1)The GSI scheme integrates a two‐quadrant DC/DC converter‐interfaced supercapacitor (SC) with the main VSI DC link, such that bidirectional inertial power exchange between the SC and the AC grid is realized, while the VSI DC link voltage is not affected. Lower cost is also achieved compared to that of the SC directly attached to the DC link as employed in [1, 13, 20, 22, 23]; 2)Synthetic inertia is realized by regulating the SC voltage along with the instantaneous grid frequency, avoiding the control noise and instability resulting from the measurement on the rate of change of grid frequency as required in [14–19]; 3)An optimal SC selection method is designed, comprehensively taking account of the synthesized inertia time constant, the covered grid frequency range and the allowable SC voltage variation range; 4)The GSI scheme can generically retrofit the DC link of already‐commissioned VSIs without modifying the original systems. This plug‐and‐play feature is an advantage over the schemes in [1, 7–9, 13–18, 20, 22, 23] requiring the modifications to the original RPG system. …”

“…Lower cost is also achieved compared to that of the SC directly attached to the DC link as employed in [1, 13, 20, 22, 23]; 2)Synthetic inertia is realized by regulating the SC voltage along with the instantaneous grid frequency, avoiding the control noise and instability resulting from the measurement on the rate of change of grid frequency as required in [14–19]; 3)An optimal SC selection method is designed, comprehensively taking account of the synthesized inertia time constant, the covered grid frequency range and the allowable SC voltage variation range; 4)The GSI scheme can generically retrofit the DC link of already‐commissioned VSIs without modifying the original systems. This plug‐and‐play feature is an advantage over the schemes in [1, 7–9, 13–18, 20, 22, 23] requiring the modifications to the original RPG system.…”

“…RPGs can be de-loaded at non-optimal power points to reserve power for synthetic inertia [14][15][16]. However, the continuous de-loading wastes the renewable power that can be generated and transmitted to the grid.…”

Flexible Active Power Control for PV-ESS Systems: A Review

“…In prior-art work, various inertia control methods were proposed for PV systems, which can be generally classified into methods without energy storage units and with energy storage units [66][67][68][69][70][71]. In [66], an inertia-based regulation strategy was proposed without energy storage for grid frequency support.…”

“…In prior-art work, various inertia control methods were proposed for PV systems, which can be generally classified into methods without energy storage units and with energy storage units [66][67][68][69][70][71]. In [66], an inertia-based regulation strategy was proposed without energy storage for grid frequency support. In this method, reserved power by modifying the MPPT algorithm has been used to regulate the frequency when there is a mismatch between power supply and demand, thus the stability of frequency can be improved.…”