Abstract
This paper presents theoretical and experimental discussions on low-voltage-ride-through operation of a modular multilevel single-delta bridge-cell (SDBC) inverter intended for utility-scale photovoltaic (PV) systems. Modern grid codes require grid-tied inverters to provide dynamic grid support during grid-fault events by injecting reactive current. This paper discusses decoupled positive- and negative-sequence reactive-current control, focusing on asymmetric voltage sags with imbalanced magnitude and phase relationships. The main objective is to present a feedforward control method based on calculation of the zero-sequence current required for achieving power balance during normal and grid-fault conditions. Moreover, this paper demonstrates a practical method that minimizes overcurrent stress in the three inverter clusters by adjusting active power drawn from PV arrays. Experimental results on a three-phase 12.6-kVA system prove that the SDBC inverter is capable of seamlessly operating through asymmetric voltage sags.
| Original language | English |
|---|---|
| Article number | 8378265 |
| Pages (from-to) | 4739-4751 |
| Number of pages | 13 |
| Journal | IEEE Transactions on Industry Applications |
| Volume | 54 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 1 Sept 2018 |
| Externally published | Yes |
Keywords
- Low-voltage-ride-through (LVRT)
- modular multilevel cascade inverters
- photovoltaic (PV) systems
ASJC Scopus subject areas
- Control and Systems Engineering
- Industrial and Manufacturing Engineering
- Electrical and Electronic Engineering
