Impact of Digital Time Delay on the Stable Grid Hosting Capacity of Large-scale Centralized Photovoltaic Plant

TL;DR

This paper examines how digital time delays in PV inverter controllers affect the maximum stable grid capacity of large-scale PV plants, using modeling and simulation to analyze stability.

Contribution

It introduces a detailed model considering digital delays and analyzes their impact on grid stability for large-scale PV plants.

Findings

Digital time delay reduces stable grid-hosting capacity.

Different delays in inverters affect system stability.

Simulation confirms theoretical predictions.

Abstract

In view of the trend towards extensive application of digital controllers in the PV inverter of large-scale centralized photovoltaic (LSCPV) plant and the increasing number of grid-connected LSCPV plants, this paper investigates in detail the influence of the digital time delay of the inverter digital controller on the stable grid-hosting capacity of LSCPV plant. The studies are based on the Norton equivalent model of the grid-connected LSCPV system considering the digital time delay when modelling the digital control system of the PV inverter. Taking into account the actual situation in LSCPV plant, the stable grid-hosting capacity of LSCPV is discussed for the cases in which the PV inverters in the LSCPV plant have the same and different digital time delay values by using the root-locus method. Simulation results of the digitally controlled grid-connected LSCPV system model validates the theoretical analysis.