A Two-Stage PV-Battery Grid Forming Control with Current Limitations on Both AC and DC Side

Integration of distributed generation (DG) has seen an exponential rise thanks to the presence of renewable sources. Most DG's employ a two-stage topology to transmit the generated power to grid or feed its local loads. In most of the literature the strategies developed for grid connected operation of a single DG or parallel operation of DGs have been developed considering a stiff DC source. However due to intermittencies in renewables and limited reserves from storage, a stiff DC source cannot be guaranteed. Thus, it would be evident to consider non stiff nature of DC source to imitate a much practical study. To ensure a stable operation on the AC side of the grid connected system, it must be guaranteed that the DC side dynamics are well within bounds. Also it must be guaranteed that the semiconductor based switching devices are not under stress. This paper focuses on the dynamics associated with the DC link and proposes a control scheme that can help mitigate them by improving the co-ordination among sources.