Detailed design of a 6 KWp grid connected PV plant with storage batteries: Part-II- Active & reactive power controllers optimization

In the dedicated literature, the grid connected inverter modelling and related control strategies, have been almost exclusively based on the concepts of d-q and α-ß transforms. However, as far as only control objectives are concerned, this work shows that straightforward approaches, such as the black box modelling techniques along with linear systems control design methods, may be successfully applied while leading to reliable, robust and cost effective solutions. In this context and in order to provide a proof of concept, the inverter whose detailed design was already presented as the first part (part-I) of the overall project work, is introduced as a realistic benchmark of a DC-AC open loop power converter. The latter inputs and outputs being mere DC quantities, a detailed black-box modelling procedure is implemented to yield the open loop corresponding parametric linear model as a simple transfer function through the adoption of an Output Error (OE) structure approach. Considered as a shared inner process, two outer closed loops are finally built up and optimized with the aim of independent active and reactive power flow control at the grid connecting point, while significant validating results are presented and discussed.