Instability of a DC microgrid with constant power loads caused by modal proximity

Wei, Du; Zheng, Kaiyuan; Wang, Hai Feng

doi:10.1049/iet-gtd.2019.0696

Cited by 5 publications

(9 citation statements)

References 34 publications

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“…The state matrix of a grid-connected PV power generation farm with inverters in parallel connection is derived from Du et al (2020a). Due to the special structure of the state matrix derived, a simple transformation of state variables is proposed and applied to decompose the state matrix.…”

Section: State Transformationmentioning

confidence: 99%

“…A grid-connected inverter may behave as an RLC circuit with negative resistance in various frequency regions, thus destabilizing the system (Harnefors, 2007;Harnefors et al, 2007;Du et al, 2020a). Moradi-Shahrbabak and Tabesh (2018) found that the damping of the oscillation mode may decrease when the capacitance and reactance corresponding to the DC link and the front-end inverter increase, bringing about the instability risk.…”

Section: Introductionmentioning

confidence: 99%

“…Studies so far in the literature have indicated that the number of inverters is an important factor affecting the oscillatory stability of a grid-connected PV generation system. The increase in the number of inverters may lead to system instability (Agorreta et al, 2011;Majumder and Bag, 2014;Shahnia, 2016;Du et al, 2020a;Fu et al, 2020;Du et al, 2021b). Shahnia (2016) found that when the total power generation capacity of a microgrid remained constant and the number of converter-interfaced distributed energy resources increased, the system stability decreased.…”

Section: Introductionmentioning

confidence: 99%

“…The mechanism of growing oscillations caused by the increased number of the PV generating units in parallel connection was analytically revealed by Du et al (2020c). A study by Du et al (2020a) is the extension of their pioneering investigation of the oscillatory stability of a grid-connected wind power generation system (Du et al, 2019). Possible small-signal instability of a grid-connected wind farm as being caused collectively by M similar wind turbine generators in parallel connection was found and examined analytically.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Small-signal oscillatory stability of a grid-connected PV power generation farm affected by the increasing number of inverters in daisy-chain connection

Zhou¹,

Cao²,

Zhao³

2023

Front. Energy Res.

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The daisy-chain connection of inverters is one of the basic configurations of the power collecting network in a grid-connected photovoltaic (PV) power generation farm. In this study, the total impact of a cluster of M similar inverters in daisy-chain connection in the PV farm is examined in the following two aspects: 1) aggregated representation of the cluster of inverters is derived for stability study based on the dynamic equivalence. The derivation confirms the rationality of representing the cluster of inverters by an aggregated inverter connected to the external system via an equivalent reactance, which is the maximum eigenvalue of the matrix of daisy-chain connection defined in the article. 2) Analysis is conducted to indicate that the risk of oscillatory instability may be collectively induced by all the inverters in the daisy-chain connection in the cluster. This explains why the increasing number of inverters may imply the possible instability risk of a PV farm. An example of a power system with a grid-connected PV power generation farm is presented in the article to demonstrate and evaluate the analytical conclusion obtained.

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Section: State Transformationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Small-signal oscillatory stability of a grid-connected PV power generation farm affected by the increasing number of inverters in daisy-chain connection

Zhou¹,

Cao²,

Zhao³

2023

Front. Energy Res.

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“…Aiming at the impact of source-side dynamic components on stability, reference [7] explored lowfrequency oscillation of the DC system caused by the AC/DC converter, and found that the constant voltage control loop and DC capacitors have a significant impact on the low-frequency oscillation, while the simplification of loads constrained the medium/high frequency stability analysis [8]. For impacts of dynamic loads: negative resistance of CPL has been well researched [5], and interactions among loads have been investigated from the point of view of the modal interaction [9] and aggregated situation [6]. However, current studies tended to ignore dynamics of sources when focused on load interactions [6].…”

Section: Introductionmentioning

confidence: 99%

Stability Analysis and Control of DC Distribution System with Electric Vehicles

Zheng¹,

Zhang²,

Zhang³

et al. 2023

Energy Engineering

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The DC distribution network system equipped with a large number of power electronic equipment exhibits weak damping characteristics and is prone to low-frequency and high-frequency unstable oscillations. The current interpretation of the oscillation mechanism has not been unified. Firstly, this paper established the complete statespace model of the distribution system consisting of a large number of electric vehicles, characteristic equation of the distribution network system is derived by establishing a state-space model, and simplified reduced-order equations describing the low-frequency oscillation and the high-frequency oscillation are obtained. Secondly, based on eigenvalue analysis, the oscillation modes and the influence of the key system parameters on the oscillation mode are studied. Besides, impacts of key factors, such as distribution network connection topology and number of dynamic loads, have been discussed to suppress oscillatory instability caused by inappropriate design or dynamic interactions. Finally, using the DC distribution example system, through model calculation and time-domain simulation analysis, the correctness of the aforementioned analysis is verified.

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Adaptive control and management of multiple nano‐grids in an islanded dc microgrid system

Abadi

Khalili

Habibi

et al. 2022

IET Generation Trans & Dist

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This paper presents an adaptive control framework for the flexible and effective management and control of clustered DC nano-grids (NGs) in an islanded DC microgrid system. It is assumed that each NG contains a photovoltaic (PV) system, a battery energy storage system (BESS), local loads, and a gateway (GW) module. Each NG has a hierarchical control system consisting of a decision-making module and low-level controllers. The decisionmaking module ensures various desirable features including plug-and-play operation of NGs, maximum utilization of PV power generations, and avoiding state of charge (SoC) violation of batteries. Moreover, an adaptive model predictive control (AMPC) strategy is proposed to regulate the voltage of the NG local DC buses in the presence of nonlinear loads. This approach improves the performance of the NG voltage control system and reduces the current ripples of BESSs, thereby enhancing the lifetime of the batteries. In addition, a smart switching consensus-based control strategy is designed that provides flexible power sharing among the NGs to balance the SoC of BESSs in which the BESSs altogether imitate the behaviour of a single cloud energy storage system (ESS). Finally, the performance of the proposed control system is verified by simulating the DC microgrid in MATLAB/Simulink.

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Instability of a DC microgrid with constant power loads caused by modal proximity

Cited by 5 publications

References 34 publications

Small-signal oscillatory stability of a grid-connected PV power generation farm affected by the increasing number of inverters in daisy-chain connection

Small-signal oscillatory stability of a grid-connected PV power generation farm affected by the increasing number of inverters in daisy-chain connection

Stability Analysis and Control of DC Distribution System with Electric Vehicles

Adaptive control and management of multiple nano‐grids in an islanded dc microgrid system

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