On the Loadability and Voltage Stability of Islanded AC–DC Hybrid Microgrids During Contingencies

Eajal, A. A.; Yazdavar, Ameen Hassan; El-Saadany, Ehab F.; Ponnambalam, K.

doi:10.1109/jsyst.2019.2910734

Cited by 31 publications

(24 citation statements)

References 30 publications

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“…The PV-curve is a very important indicator for studying the stability of a system. It indicates the maximum load limit, beyond which a voltage collapse occurs [26]. The maximum loadability of node 15 (the weakest node of the network) is investigated.…”

Section: Voltage Stability Analysismentioning

confidence: 99%

A Three-Phase Weather-Dependent Power Flow Approach for 4-Wire Multi-Grounded Unbalanced Microgrids With Bare Overhead Conductors

Pompodakis

Ahmed²,

Alexiadis

2021

IEEE Trans. Power Syst.

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Conventional power flow algorithms assume that the network resistances and reactances remain constant regardless of the weather and loading conditions. Although the impact of the weather in power flow analysis has been recently investigated via weather-dependent power flow (WDPF) approaches, the magnetic effects in the core of Aluminum Conductor Steel Reinforced (ACSR) conductors have not been explicitly considered. ACSR conductors are widely used in distribution networks. Therefore, this manuscript proposes a three-phase weather-dependent power flow algorithm for 4wire multi-grounded unbalanced microgrids (MGs), which takes into consideration the impact of weather as well as the magnetic effects in the core of ACSR conductors. It is shown that the magnetic effects in the core can significantly influence the power flow results, especially for networks composed of single-layer ACSR conductors. Furthermore, the proposed algorithm explicitly considers the multi-grounded neutral conductor, thus it can precisely simulate unbalanced low voltage (LV) and medium voltage (MV) networks. In addition, the proposed approach is generic and can be applied in both grid-connected and islanded networks. Simulations conducted in a 25-Bus unbalanced LV microgrid highlight the accuracy and benefit of the proposed approach, while its computation performance is tested in the IEEE 8500-Node network.

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Section: Voltage Stability Analysismentioning

confidence: 99%

A Three-Phase Weather-Dependent Power Flow Approach for 4-Wire Multi-Grounded Unbalanced Microgrids With Bare Overhead Conductors

Pompodakis

Ahmed²,

Alexiadis

2021

IEEE Trans. Power Syst.

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“…Voltage stability can be improved by adding DC links among radial feeders. But, AC/DC loops change the network topology from radial to mesh, thus making its operation and control more difficult [58]. Appropriate coordination of Q-V droops is crucial to avoid high circulating reactive power flows, which may result in large voltage oscillations [59].…”

Section: Coordination Of Voltage Control Loopsmentioning

confidence: 99%

“…Higher droop gains in the primary control can reduce the effect of line resistances on the current sharing accuracy, but also can cause large voltage drops in the output terminal of the converters [49]. Furthermore, during overloading and islanding conditions, DGs with voltage support capability may have to operate near their limits [58]. Some of these DGs could reach their limits due to a subsequent contingency.…”

Section: Coordination Of Voltage Control Loopsmentioning

confidence: 99%

Voltage Stability of Power Systems with Renewable-Energy Inverter-Based Generators: A Review

et al. 2021

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The main purpose of developing microgrids (MGs) is to facilitate the integration of renewable energy sources (RESs) into the power grid. RESs are normally connected to the grid via power electronic inverters. As various types of RESs are increasingly being connected to the electrical power grid, power systems of the near future will have more inverter-based generators (IBGs) instead of synchronous machines. Since IBGs have significant differences in their characteristics compared to synchronous generators (SGs), particularly concerning their inertia and capability to provide reactive power, their impacts on the system dynamics are different compared to SGs. In particular, system stability analysis will require new approaches. As such, research is currently being conducted on the stability of power systems with the inclusion of IBGs. This review article is intended to be a preface to the Special Issue on Voltage Stability of Microgrids in Power Systems. It presents a comprehensive review of the literature on voltage stability of power systems with a relatively high percentage of IBGs in the generation mix of the system. As the research is developing rapidly in this field, it is understood that by the time that this article is published, and further in the future, there will be many more new developments in this area. Certainly, other articles in this special issue will highlight some other important aspects of the voltage stability of microgrids.

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“…Hence, stability analysis results may prompt reconfiguration of the grid topology or modification of the control parameters to avoid possible contingencies. For instance, reference [18] analyzes the DC voltage stability in AC/DC hybrid microgrids to raise awareness among operators and planners on incorporating this stability study into the planning stage's contingency analysis. To date, few articles have considered stability criteria in the expansion planning of the AC grids.…”

Section: Introductionmentioning

confidence: 99%

Optimal Linear Controller for Minimizing DC Voltage Oscillations in MMC-Based Offshore Multiterminal HVDC Grids

et al. 2021

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The paper aims at minimizing DC voltage oscillations in offshore multiterminal highvoltage direct current (HVDC) grids based on modular multilevel converters (MMCs). The DC voltage stability is a crucial factor in multiterminal HVDC networks since it is associated with the grid power balance. Furthermore, DC voltage oscillations can cause the propagation of significant disturbances to the interconnected AC grids. This paper proposes an optimal control technique based on semidefinite programming to improve the DC voltage stability margins under the worst-case perturbation scenario. A centralized optimal linear feedback controller is introduced to achieve this goal while ensuring compliance with the control inputs' and state variables' constraints. Furthermore, the methodology is adapted to develop a decentralized optimal linear feedback controller with naturally decoupled constraints on the control inputs and state variables. It is shown that the proposed centralized and decentralized optimal linear controllers can minimize the DC voltage oscillations under the worst-case perturbation scenario in the presence or absence of the droop control gain. The performance of these controllers is verified via eigenvalue stability analysis and time-domain simulations of the MMC-based four-terminal HVDC test grid. Finally, a DC voltage oscillation index is introduced as a potential decision-support criterion. Its applicability is exemplified by identifying, among several options, the HVDC link that gives minimum DC voltage oscillations between independent point-to-point networks while considering the wind intermittency effect.INDEX TERMS DC voltage oscillations, modular multilevel converter, offshore multiterminal HVDC grid, centralized and decentralized optimal linear feedback controller

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On the Loadability and Voltage Stability of Islanded AC–DC Hybrid Microgrids During Contingencies

Cited by 31 publications

References 30 publications

A Three-Phase Weather-Dependent Power Flow Approach for 4-Wire Multi-Grounded Unbalanced Microgrids With Bare Overhead Conductors

A Three-Phase Weather-Dependent Power Flow Approach for 4-Wire Multi-Grounded Unbalanced Microgrids With Bare Overhead Conductors

Voltage Stability of Power Systems with Renewable-Energy Inverter-Based Generators: A Review

Optimal Linear Controller for Minimizing DC Voltage Oscillations in MMC-Based Offshore Multiterminal HVDC Grids

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