Large-signal model of DC micro-grid systems feeding a constant power load

Islanded AC-DC hybrid microgrids composed of new energy sources, constant power loads and energy storage system are typical non-linear systems, and guaranteeing large signal stability is a key issue. In this paper, the non-linear model of islanded AC-DC hybrid microgrids is established, and large signal stability criteria are obtained. Considering reference current limitation of the energy DC-AC converter, the derived large signal stability criterion gives important constraints on the constant power loads power, the power of energy storage unit, DC bus voltage, the inductor and equivalent resistance of the AC filter, DC capacitor, the proportional parameter of the inner current controller and the maximum instantaneous power of the DC-AC converter. The paper is summarized as follows. Firstly, the equivalent model of the AC-DC hybrid microgrids in DQ rotating frame is established. Then based on mixed potential theory, the mixed potential model is constructed, and large signal stability criterion is derived and optimized considering the reference current limitation of the DC-AC converter. Finally, the presented criterion is verified by simulation and experimental results.

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“…v dc is the DC voltage, and R L is DC side load. e L is DC side electromotive force, and N is reference ground [29].…”

Section: Abc-dq Coordinate Transformation Of the Bidirectional Dc-ac ...mentioning

confidence: 99%

“…Based on Figure 1 a simulation model of AC-DC hybrid microgrids in island mode is built in Matlab software to verify the correctness of the derived large signal stability criterion in Equation (29). The parameters of system are as shown in Table 1.…”

Section: Simulationsmentioning

confidence: 99%

Large signal stability criterion of AC–DC hybrid microgrids with constant power loads considering reference current limitation

Liu

Song

et al. 2022

IET Generation Trans & Dist

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“…Using the mathematical model of the DCMGs derived by using the DQ and GSSA methods (described in [40]), the (7). The dynamic model of DCMGs with the loop-cancellation technique can be expressed as in (A-2).…”

Section: Stabilization Of the Dcmgs Feeding An Ideal Cplmentioning

confidence: 99%

Stabilization of DC MicroGrid Systems Using the Loop-Cancellation Technique

Pakdeeto

Areerak

Bozhko

2021

IEEE J. Emerg. Sel. Topics Power Electron.

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DC micro-grid systems feed power to constant power loads via transmission lines. Although these systems are commonly used worldwide, constant power loads have negative impedance effects. These loads can significantly degrade the system stability. Therefore, stability study is very important to avoid inefficient operations. The model proposed in this paper can be derived by using a combination of the DQ method and the generalized state-space averaging method. This model is suitable for analyzing the system stability using the eigenvalue theorem. For stability analysis, the proposed DC micro-grid system will be unstable before reaching the rated power when the irradiance is equal to 0 W/m 2 . Consequently, the loop-cancellation technique is applied to mitigate the unstable operation until the operation at the rated power can be achieved. Experimental and simulation results were used to confirm the theoretical analysis. The system performed well, and the results proved that the system could be stabilized by using the proposed technique.

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“…However, this approach exists limitation on the closed-loop bandwidth of the source-side converter, and the requirement for the resonant frequency of the LC input filter adds additional constraints to the design of the LC filter. In addition, the smart resistor can be operated as a linear resistor CPL [105], which reduces the bulk of the capacitor and also assists decouple the power supply and load control. Thus, the load is dynamically stabilized locally and the overshoot current is made impossible.…”

Section: A Virtual Impedance Construction For Cplsmentioning

confidence: 99%

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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Large-signal model of DC micro-grid systems feeding a constant power load

Cited by 7 publications

References 8 publications

Large signal stability criterion of AC–DC hybrid microgrids with constant power loads considering reference current limitation

Large signal stability criterion of AC–DC hybrid microgrids with constant power loads considering reference current limitation

Stabilization of DC MicroGrid Systems Using the Loop-Cancellation Technique

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

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