Modeling and Control of a Mining Microgrid Consisting of Multiple Electrified Drill Rigs

The electrification of large-scale mining equipment poses significant challenges for weak and remote power networks, where high inrush currents, low power factor, total harmonic distortion, and stability concerns can severely degrade system performance. While stability and power quality have often been studied separately, an integrated analysis tailored for weak mining grids remains lacking.

In this presentation, I will discuss the dynamic behavior of Direct-on-Line motors, Passive Front-End rectifiers, and Active Front-End converters in grid-following and grid-forming modes, clarifying their comparative suitability for mining microgrids. A state-space modeling framework is introduced to capture the interactions among converters, induction motors, and the weak grid, incorporating LCL filter sizing, control loop dynamics, phase-locked loop, and droop control. The framework is validated against nonlinear time-domain simulations, with consistent results in both stable and unstable regimes.

Case studies on a representative open-pit feeder highlight startup current overshoot, steady-state power factor, harmonic distortion, and stability margins as evaluation metrics. The results emphasize the influence of phase-locked loop tuning on grid-following stability, the synchronization aggressiveness of grid-forming droop control, and the potential of hybrid configurations. In particular, I will show how replacing part of the Direct-on-Line based rigs with Active Front-End converters can substantially improve both power quality and stability margins without requiring a complete system overhaul.