A Frequency-Dependent Virtual Impedance for Voltage-Regulating Converters Feeding Constant Power Loads in a DC Microgrid

Hussain, Mosaddique Nawaz; Mishra, Rahul; Agarwal, Vivek

doi:10.1109/tia.2018.2846637

Cited by 66 publications

(37 citation statements)

References 31 publications

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“…However, the dc MG would become unstable due to the negative impedance characteristics introduced by CPLs [44]- [46]. Thus, to solve the problem of system instability caused by large-scale access of constant power load in dc MG, various strategies for enhancing the system stability is reviewed in this section: applying a virtual impedance to cancel out the negative impedance [47], employing model prediction to counteract the negative impedance [48], utilizing feedback control to cancel out the negative impedance [49], [52].…”

Section: Load Stability Analysis In the DC Microgridsmentioning

confidence: 99%

“…Therefore, in order to improve the damping of the dc MG with CPL, a virtual impedance stabilization control method can be used to introduce a virtual impedance into the output filter [102], the unstable pole caused by CPLs moves to the stable region to ensure the system stability. Furthermore, considering the voltage drop under large load variation conditions, a new active damping technique for CPL low damping input LC filter stabilization scheme is designed in [47]. In addition, a new type of active damping method is proposed in [103], which is reloaded by superconducting capacitors of the dc MG, hence the dc bus voltage oscillation can be eliminated and the system stability can be enhanced.…”

Section: A Virtual Impedance Construction For Cplsmentioning

confidence: 99%

“…However, with the negative impedance characteristics of CPLs, dc MGs are easier to be unstable due to the reduced system damping [44]- [46]. Thus, the system damping can be elevated by applying virtual impedance [47], model prediction [48], feedback control [49], [50], etc. Moreover, a linear programming algorithm can be applied to enhance the system robustness.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Review of Power Sharing, Voltage Restoration and Stabilization Techniques in Hierarchical Controlled DC Microgrids

et al. 2019

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In order to overcome the problem of power generation in distributed energy, microgrid(MG) emerges as an alternative scheme. Compared with the ac microgrids, the dc microgrids have the advantages of high system efficiency, good power quality, low cost, and simple control. However, due to the complexity of the distributed generation system, the conventional droop control shows the drawbacks of low current sharing accuracy. Therefore, the improved primary control methods to enhance current sharing accuracy are systematically reviewed, such as particle swarm optimization programming, probabilistic algorithm and voltage correction factor scheme. However, it is difficult to achieve stable and coordinated operation of the dc microgrids by relying on the primary control. Hence, the various secondary control approaches, such as dynamic current sharing scheme, muti-agent system (MAS) control and virtual voltage control methods have been summarized for voltage regulation. Furthermore, the energy management system (EMS), modular-based energy router (MBER) and other coordinated control methods are reviewed to achieve power management. Besides, various control methods to compensate the effect of communication delay are summarized. Moreover, linear matrix inequality (LMI), Lyapunov-Krasovskii functional stability and Takagi-Sugeno model prediction scheme can be adopted to eliminate the influence of communication delay. In addition, due to the constant power loads (CPL) exhibit negative impedance characteristics, which may result in the output oscillation of filter. Thus, various control approaches have been reviewed to match the impedance, such as the nonlinear disturbance observer (NDO) feedforward compensation method, linear programming algorithm, hybrid potential theory and linear system analysis of polyhedral uncertainty. The merits and drawbacks of those control strategies are compared in this paper. Finally, the future research trends of hierarchical control and stability in dc microgrids and dc microgrid clusters are also presented. INDEX TERMS DC microgrid, nonlinear droop control, multi-agent system, consensus control, communication delay, constant power load, hierarchical control.

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Section: Load Stability Analysis In the DC Microgridsmentioning

confidence: 99%

Section: A Virtual Impedance Construction For Cplsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Review of Power Sharing, Voltage Restoration and Stabilization Techniques in Hierarchical Controlled DC Microgrids

et al. 2019

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“…The VI is added to the existing control block diagram to perform the same behavior as the dotted line circuit. By adding a VI, the output impedance is reshaped at frequencies where impedance overlap occurs due to insufficient damping in the source converter [32], [33]. Thus, it can meet Middlebrook's stability criterion and stabilize the system.…”

Section: Stability Enhancement Control Schemementioning

confidence: 99%

Impedance-Based Modeling and Common Bus Stability Enhancement Control Algorithm in DC Microgrid

Lee

Park

et al. 2020

IEEE Access

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In this paper, impedance modeling of a DC microgrid system consisting of a source and load converter, including an input filter, is performed. Impedance-based modeling has been used to derive mathematical models of the output impedance of the source converter and the input impedance of the load converter. The correlation between the converter interaction and system stability is analyzed based on the mathematical model. An impedance-based stability analysis is used to determine the system stability by analyzing the interactions among the converters in the DC microgrid system. Middlebrook's stability criterion, which uses the impedance transfer function, is applied to determine system stability. Moreover, in this paper, a stability enhancement control algorithm is proposed to resolve the system instabilities resulting from interaction among the converters and the distortion caused by the harmonics emanating from the AC input. The proposed stability enhancement control algorithm consists of a feed-forward type virtual impedance (VI) and a proportional-resonant (PR) controller. The validity of the proposed method is demonstrated by the results of the response characteristics in the frequency domain, and the effectiveness of the proposed control algorithm is verified via simulations and prototype experimental models.

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“…A distributed oscillation suppression control strategy is proposed to damp the resonance caused by LC filter in DC microgrids [10]. Oscillations can be damped by inserting a virtual impedance at the output of voltage-regulating converters to offset the negative resistance of CPLs [11]. In [12][13][14], a converter introduces a virtual resistor by feeding the output current back to the voltage control loop, which simulates the passive damping control method.…”

Section: Introductionmentioning

confidence: 99%

Optimised damping control of islanded DC power systems using state feedback

Yuan

Zhang

et al. 2020

IET Generation, Transmission & Distribution

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A Frequency-Dependent Virtual Impedance for Voltage-Regulating Converters Feeding Constant Power Loads in a DC Microgrid

Cited by 66 publications

References 31 publications

Review of Power Sharing, Voltage Restoration and Stabilization Techniques in Hierarchical Controlled DC Microgrids

Review of Power Sharing, Voltage Restoration and Stabilization Techniques in Hierarchical Controlled DC Microgrids

Impedance-Based Modeling and Common Bus Stability Enhancement Control Algorithm in DC Microgrid

Optimised damping control of islanded DC power systems using state feedback

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