Source-Side Virtual RC Damper-Based Stabilization Technique for Cascaded Systems in DC Microgrids

Abstract

Cascaded connection of power converters is a dominant connection form in DC microgrids. In such systems, despite the possible instability caused by the impedance interactions between the individually designed converters, tightly regulated load converters acting as constant power loads (CPLs) tend to destabilize the system owing to their negative resistance characteristics. Hence, this paper proposes a new virtual series RC damper in parallel with the source-side converter's capacitor without compromising the load's dynamic performance. Using this design-oriented active damping method, which utilizes a simple control structure with a more straightforward tuning of the control parameter, the stability and performance of the system are guaranteed. The feasibility and robustness of the suggested active stabilization idea against unanticipated variations in input voltage amplitude, and CPL power rating (load changes) as well as step changes in output voltage reference, are also authenticated. The control and operation principles, as well as the circuit physical meaning realized by the presented technique for three cascaded systems comprising the basic DC/DC converters feeding CPLs, are theoretically analyzed. Simulation and experimental results are provided to validate the effectiveness of the proposed active stabilizer.

Enhancement of Stability on Dc Microgrid Using Dual Seires Virtual Impedance Based Fuzzy Controller Under Variation of Constant Power Load

“…Where, C vir represent as the VI coefficient of the system, it will be assuming as virtual impedance. Corresponding to (17), ΔP vir can be satisfactorily modified by varying C vir , then the inertia of the MGs can be controlled.…”

“…The input-output linearization technique proposed in [14] for a boost converter feeding a hybrid of CPL and resistive load is believed to cancel out the nonlinearities caused by CPL, uses the Kharitonov rectangle-based programming technique [15] to achieve the stability of the main converter feeding a cascaded converter in a multi-converter system. Destabilisation in DC MGs caused by CPL is investigated, and an active damping method [16] and a droop mode method [17] are used to try to stabilise the device.…”

A Model Predictive Control Strategy for Performance Improvement of Hybrid Energy Storage Systems in DC Microgrids

“…DC MGs can be considered as viable solutions for rural electrification, resilience enhancement of power grids, and supporting local energy communities [3]. However, control of DC MGs can be challenging in the presence of constant power loads (CPLs) and pulsed power loads (PPLs) which require fast dynamic response and large stability margin of control system [4][5][6]. To tackle this challenge, highly-dispatchable distributed energy resources (DERs) as well as advanced control and management techniques are required to improve the transient response, stability, and flexibility of the system [7].…”

“…where dc v is the MG DC bus voltage. Thus, based on (1) to (5), the nonlinear dynamical model of the closed-loop system can be obtained as…”

Adaptive Damping Control to Enhance Small-Signal Stability of DC Microgrids

“…In [24]- [26], virtual-impedance-based strategies, realized by feed-forward or feedback of disturbance variables, are proposed to alleviate the low-frequency problem made by the droop controllers of DC-MGs. In [28], a virtual series RC-based active damping control strategy is presented for DC/DC converters loaded by CPLs to improve their dynamic response and give stabilization within the DC-MG. The performance of virtual impedancebased methods is deeply influenced by the systematic gains, the tuning of which is still a challenge to be undertaken.…”