Multi-Mode Voltage Sag/Swell Generator Based on Three-Phase Inverter Circuit

Abstract

The voltage ride through capability of the major auxiliary variable-frequency drive (VFD) in large thermal power plants is the key technical issue of power grid and source coordination. In order to test the high voltage ride through (HVRT) and low voltage ride through (LVRT) capability of the auxiliary VFD, it is necessary to develop a power supply to simulate different grid voltage sag and swell accurately. In this paper, a generator (VSSG) based on the common three-phase inverter circuit that can simulate multi-mode voltage sag/swell is proposed. The designed main circuit consisting of transformer, rectifier, DC split capacitors, three-phase inverter, and LC-filter can generate single-phase and three-phase voltage sag, swell, and phase angle jumping flexibly. The developed control strategies composed of the double closed-loop control and the neutral voltage balance control achieve accurate output, fast dynamic response, and step-less adjustment. Simulation and experiment results verify the multi-mode voltage simulation performances of the proposed VSSG, which can be effectively used to emulate power grid voltage sag and swell phenomena under the IEEE 1159 and IEC standards.

Power Converter Resonant Control for an Unbalanced and Non-Constant Frequency Supply

“…The system in Figure 1 allows decoupling the load with respect to the distorted grid source, with the load frequency and amplitude determined by the load-side inverter control algorithm; the literature shows several ways to control them, such as those in [ 16 , 17 , 18 , 19 , 20 ]. Therefore, this study did not focus on load inverter control but only on the grid-side converter, which must deal with a distorted source (as the one presented in microgrids and weak grid systems), delivering, despite the unpredictable behavior of the grid, a controlled DC voltage to feed the load-side inverter with the desired DC link voltage.…”