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.
Highlights
Voltage sag and swell are the common phenomena of power grid
At present most research is focused on the simulation of the grid voltage sag, i.e., voltage sag generator (VSG), which is mostly used in the field of wind power system test [4,5], power quality improvement in wind farm [6] and DC supply system [7], and other renewable energy systems [8,9,10]
In view of the above, this paper presents a new voltage sag/swell generator (VSSG) based on the common three-phase inverter circuit and SPWM control, which can emulate multi-mode of voltage sag/swell and phase angle jumping
Summary
Voltage sag and swell are the common phenomena of power grid. Voltage sag is caused by grid short circuit, access of large capacity load and the dual power supply switching, etc. The voltage sag depth and duration are adjusted by controlling the shunt impedance value and its time of switching into the circuit This method is simple and easy to implement, but it has the drawbacks of large energy consumption, low accuracy, and adjustment discontinuity. The power-electronics-converter-based grid voltage sag or swell generator deserves more attention, which is mostly on the basis of inverter circuit [5,20,21,22,23,24,25]. In view of the above, this paper presents a new voltage sag/swell generator (VSSG) based on the common three-phase inverter circuit and SPWM control, which can emulate multi-mode of voltage sag/swell and phase angle jumping.
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