Experimental evaluation of advanced control strategies for high-blockage cross-flow turbine arrays

TL;DR

This study experimentally assesses various control strategies for high-blockage cross-flow turbine arrays, finding limited efficiency improvements and suggesting simpler control may suffice at high blockage ratios.

Contribution

It provides the first experimental comparison of control strategies for high-blockage cross-flow turbine arrays, highlighting their limited impact on efficiency.

Findings

Control strategies did not significantly improve efficiency.

Intracycle speed control generally reduced performance.

Simpler control approaches may be adequate at high blockage ratios.

Abstract

In river or tidal channels, cross-flow turbines can achieve higher blockage ratios than other turbine variants, and are therefore able to achieve higher efficiencies. Here, we experimentally investigate how array control strategies might further influence the efficiency of a high-blockage dual-rotor cross-flow turbine array. Array performance is evaluated under coordinated constant speed control, uncoordinated torque control, and coordinated intracycle speed control at blockage ratios of 35% - 55%. In contrast to prior work at lower blockage, the evaluated control strategies do not yield significant improvements in efficiency and intracycle control is found to generally reduce array performance. While these results suggest limited benefits to more advanced control strategies at high blockage, this has the benefit of simplifying the system design space for array-level control.