Control strategy of mine-used LCL three-level static var generator

Abstract

In order to adapt to special environment of coal mine and reduce volume and quality of mine-used static var generator(SVG), LCL filter and three-level inverter were used as main circuit topology of mine-used SVG. For problems of current resonance of LCL filter and potential imbalancein three-level inverter, a control strategy of mine-used LCL three-level SVG based on series double current loop active damping control and dynamic proportional space vector modulation was proposed. On the basis of PI control of grid-side current outer loop, LCL filter has damping characteristics by adding feedback control of filter capacitor current inner loop, which can effectively suppress current resonance. Dynamic proportional space vector modulation introduces dynamic proportional adjustment factor into basic space vector to control average neutral-point current in unit switching cycle in realtime, so as to achieve balance control of three-level neutral-point potential. The simulation and experimental results verify the feasibility and good effect of the control strategy under condition of LCL filter without damping resistance and small DC busbar capacitance.

Keywords

• coal mine power grid
• static var generator
• lcl filter
• three-level inverter
• current resonance
• neutral-point potential balancing
• active damping
• space vector modulatio