Active Load Stabilization of Cascaded Systems in DC Microgrids Using Adaptive Parallel-Virtual-Resistance Control Scheme

Active Stabilization Techniques for Cascaded Systems in DC Microgrids

“…This is because connecting them to other circuits will no longer maintain the stability conditions of closed-loop converters designed as a freestanding device and may impose unforeseeable dynamic responses on the system [9], [12], and [15]. Also, these predominant structures in DC MG applications are commonly loaded with large active loads such as motor drives or electronic loads, which all these loads tend to be energized by POL converters [3], [16]. These loads act as instantaneous CPLs when tightlycontrolled by their respective converters, which have a rapid dynamic response with minimal output voltage ripple [9]- [12], [17], and [18].…”

“…These loads act as instantaneous CPLs when tightlycontrolled by their respective converters, which have a rapid dynamic response with minimal output voltage ripple [9]- [12], [17], and [18]. In this case, when the bandwidth and control loop gain of the load side converter is adequately greater than that of the converter at the source side [9], [11], CPLs draw constant power from their upstream circuit, regardless of its terminal voltage [14]- [16]. CPLs introduce incremental negative resistance characteristic for their upstream circuit.…”

“…Where in V , in I , in P , and o P are the input voltage, input current, input power, and output power of load converter, respectively. After adding the disturbances in (2-1) and considering the behavior of the load converter as CPL [16], [19], ( ) (…”

“…According to (2)(3), though the inherent negative resistance property of CPL ensures the fast-dynamic performance of the load converter, it will negatively affect the stability of the cascaded systems [2], [9], [19], and [20]. Hence, if the network is not supported with a suitable stabilization scheme over during the transient and any unwanted disturbance in the system, the voltage will go zero as the current goes to infinity, and vice versa [16], [17]. Finally, the system state variables will no longer return to equilibrium and the system will become unstable.…”

“…1.2 is one of the vital concerns in obtaining a stable LVDC network. In addition, the accepted control approach must be robust enough to ensure the stability of the system against anticipated variations while simultaneously maintaining fast dynamic performance [9]- [16].…”