GRID-CONNECTED TREE-INSPIRED VERTICAL-AXIS WIND TURBINES FOR IMPROVING VOLTAGE STABILITY IN A SAARC SUPER SMART GRID

Abstract

The growing integration of variable renewable generation into interconnected power networks increases the need for effective voltage regulation during wind fluctuations, demand changes, and grid disturbances. This study proposes a grid-connected, tree-inspired vertical-axis wind turbine (VAWT) system for improving voltage stability in a simulated South Asian Association for Regional Cooperation (SAARC) super smart grid. The proposed structure combines multiple small VAWTs on a branching support arrangement with a common DC link and grid-interfacing converter. A coordinated control strategy regulates active-power injection and provides reactive-power support according to local bus-voltage conditions. A six-zone interconnected grid model was developed to represent regional generation, transmission links, and variable demand. The illustrative simulation dataset comprised 52,560 ten-minute operating intervals over one year, incorporating wind-speed profiles, electricity demand, turbine output, and bus-voltage measurements. Performance was compared across three configurations: the baseline grid, conventional grid-connected VAWTs, and the proposed tree-inspired system. Each configuration was tested under wind variability, peak-load conditions, line outages, and short-circuit faults. Voltage deviation, minimum bus voltage, voltage-stability index, and post-fault recovery time were used as evaluation measures. In the illustrative results, the proposed system reduced mean voltage deviation by 27.4% relative to the baseline and 13.2% relative to conventional VAWTs. During the most severe fault scenario, minimum voltage increased from 0.79 to 0.86 per unit, while recovery time decreased from 2.8 to 1.9 seconds. The voltage-stability index improved by 15.6% compared with the baseline. Reactive-power support produced the largest benefit during peak demand combined with low wind output. These findings suggest that coordinated converter control could enable distributed tree-inspired VAWTs to contribute to voltage stability in an interconnected regional grid. The proposed framework offers a basis for assessing turbine placement, converter capacity, and voltage-support control in future SAARC energy-interconnection studies. Physical turbine testing and validation using actual regional network data remain necessary.