DQ Admittance Modeling of SVG Considering DC Voltage Fluctuation

Because the static var generator (SVG) has the characteristics of flexible and rapid compensation of reactive power, it is widely used in new energy power stations. Through dynamic reactive power regulation, the power quality of the regional system is improved. Since the output power of SVG is close to pure reactive power, its admittance characteristics are significantly different from those of ordinary inverters. Therefore, considering the influence of DC side voltage fluctuation on AC side current, as well as the dynamic characteristics of phase-locked loop (PLL), current inner loop, voltage loop and power outer loop, the dq axis admittance model of SVG is established in detail. The correctness of the admittance calculation results is verified by frequency sweep measurement. In addition, this paper analyzes the small signal admittance characteristics of SVG from the two perspectives of dq subsystem coupling characteristics and negative conductance characteristics.