Distributed optimal operation of hierarchically controlled microgrids

Wu, Xiangyu; Chen, Laijun; Xu, Yin; He, Jinghan; Fang, Chen

doi:10.1049/iet-gtd.2018.5620

Cited by 20 publications

(18 citation statements)

References 25 publications

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“…Other proposals, as the ones presented in [22][23][24][25][26][27], are characterised by including an optimal power dispatch in the hierarchical control structure. In these works, the result obtained is a reduction in the total generation cost compared with similar control schemes.…”

Section: Introductionmentioning

confidence: 99%

Droop‐free hierarchical control strategy for inverter‐based AC microgrids

Rey

Vergara

Castilla³

et al. 2020

IET Power Electronics

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Hierarchical schemes are widely used for the design of inverter-based AC microgrids control strategies. To ensure a reliable operation, hierarchical control must consider together all the functionalities that allow the regulation of key variables and guarantee a safe transition between operation modes. Conventionally, in the literature are proposed three-layer schemes which present relevant drawbacks: they include limited functionalities and they use droop method for the primary layer which, despite its decentralized nature, suffers from issues that have motivated the development of alternative strategies. Considering this, the contribution of this paper is twofold. First, a droop-free hierarchical control strategy that satisfy a proper operation of AC microgrids is proposed. Control objectives such as power-sharing, frequency regulation, optimal power dispatch, and voltage regulation are considered. Second, a closed-loop small-signal model, which facilitates the control parameters design and fills a gap in the literature is presented. Differences between the proposal and previous controls are discussed. Selected tests are carried out in a laboratory microgrid under different conditions, including normal operation and the response to failures in the central controller and to communication impairments. The experimental results show a good performance of the proposal even in adverse conditions.

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Section: Introductionmentioning

confidence: 99%

Droop‐free hierarchical control strategy for inverter‐based AC microgrids

Rey

Vergara

Castilla³

et al. 2020

IET Power Electronics

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“…• The proposed centralised concept does not require communication elements and operates only on the basis of local measurement signals. The reference literature mainly suggests concepts with dispersed regulatory elements [10,14,17,23] or such that require communication systems which hinder their practical realisation, especially in case of more complex microgrids [15,16,23]. Due to the absence of communication systems, the proposed technique has a lower cost and a greater reliability.…”

Section: Introductionmentioning

confidence: 99%

Technique for stability enhancement of microgrids during unsymmetrical disturbances using battery connected by single‐phase converters

Milošević

Đurišić

2020

IET Renewable Power Generation

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This study proposes a technique for the enhancement of the stability of microgrids during unsymmetrical temporary faults in the distribution network. In order to enhance the transient stability and the quality of voltage in the microgrid during different disturbances caused by faults in the distribution network, this study proposes a concept with a centralised battery energy storage system. The battery is connected to the network through single-phase converter units which are to be implemented in every phase so that they can inject independently both the active and reactive power in certain phases. The proposed technique enhances the transient stability of microgrids and provides symmetrical operating conditions for consumers and generators in it during all temporary symmetrical and unsymmetrical faults in the distribution network. An innovative concept has been proposed for managing the balance of active and reactive power that uses, as control variables, magnitude and voltage phase angle at the point of connection of the microgrid to the distribution system. The proposed concept and technique have been tested on the IEEE 33 BUS system with additional sources. The dynamic simulations of disturbances and the verification of the proposed technique have been performed in DIgSILENT PowerFactory software.

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“…The authors of [30] and [31] also proposed distributed control methods to restore the voltage and frequency deviation. Some distributed control methods are proposed to coordinate the secondary and tertiary control together [32][33][34]. However, all of them could not be performed in a communication-free manner.…”

Section: Introductionmentioning

confidence: 99%

Frequency and State-of-Charge Restoration Method in a Secondary Control of an Islanded Microgrid without Communication

Lee

Kim

2020

Applied Sciences

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This paper presents a control method for inverter-interfaced distributed generation (DG) and energy storage systems (ESSs) in an islanded microgrid. The proposed method is focused on secondary control, particularly frequency restoration and maintaining the ESSs’ state of charge (SOC). To recover frequency deviation due to load change, an ESS is used as a droop-controlled grid-forming source. However, the grid-forming ESS cannot manage its own SOC, since it cannot control its own output power; hence, grid-feeding DGs are used to maintain the SOC within a desired range. Management of the SOC, as well as frequency restoration, is conducted by using local controllers without any communication devices, since dependency on communication may deteriorate system reliability in the case of failure. The proposed method for maintaining SOC can be realized by adjusting the system frequency, which is the only value that can be measured locally with almost the same value at every node in a steady state. Frequency restoration can be achieved by a simple ON/OFF scheme of the integral controller with a hysteresis loop to solve problems caused by differences between frequency measurements or set points among DGs.

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Distributed optimal operation of hierarchically controlled microgrids

Cited by 20 publications

References 25 publications

Droop‐free hierarchical control strategy for inverter‐based AC microgrids

Droop‐free hierarchical control strategy for inverter‐based AC microgrids

Technique for stability enhancement of microgrids during unsymmetrical disturbances using battery connected by single‐phase converters

Frequency and State-of-Charge Restoration Method in a Secondary Control of an Islanded Microgrid without Communication

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