A three-phase community microgrid comprised of single-phase energy resources with an uneven scattering amongst phases

Shahnia, Farhad; Chandrasena, Ruwan P.S.

doi:10.1016/j.ijepes.2016.06.010

Cited by 17 publications

(8 citation statements)

References 40 publications

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“…The parameters of the UI and DERs, and maximum loads capacities are shown, respectively, in Table II and Table III. Herein, in order to evaluate the UI contribution to re-circulate power flow among the system phases through its DC link, the UI capacity of contributing to active power during grid-connected mode is set to zero (i.e., it runs similarly to an active power filter or DSTATCOM [7]). Whereas, during islanded operation it is enabled to process active power within its power rating capacity.…”

Section: Simulation Resultsmentioning

confidence: 99%

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Optimal Multiobjective Control of Low-Voltage AC Microgrids: Power Flow Regulation and Compensation of Reactive Power and Unbalance

Brandão

Ferreira

Alonso

et al. 2020

IEEE Trans. Smart Grid

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The presence of single-phase distributed generators unevenly injecting active power in three-phase microgrids may create undesired upstream current unbalance. Consequently, voltage asymmetry and even active power curtailment may occur in such networks with negative economic impact. Thus, this paper proposes an optimal multiobjective approach to regulate the active and reactive power delivered by distributed generators driven by a three-layer hierarchical control technique in low-voltage microgrids. This method does not require previous knowledge of network parameters. The multiobjective algorithm is implemented in the secondary level achieving optimal dispatch in terms of maximizing the active power generation, as well as minimizing the reactive power circulation and current unbalance. By the existence of a utility interface three-phase converter placed at the point-ofcommon-coupling, the proposed control can regulate the power circulating among the microgrid phases, and the microgrid structure can withstand grid-connected and islanded operating modes. The path for interphase power circulation through the DClink of the utility interface allows the multiobjective algorithm to achieve better results in terms of generation and compensation compared to the system without utility interface. The proposed method is assessed herein by computational simulations in a threephase four-wire microgrid under realistic operational conditions.

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Section: Simulation Resultsmentioning

confidence: 99%

“…A decentralized approach proposed in [7] focuses on having a DSTATCOM installed at the MG's PCC to mitigate reactive power and current unbalance by circulating power among the network's phases through its DC link. DERs are driven by constant PQ control when grid-connected, or following V/f droop control upon islanded MG operation.…”

Section: A Literature Reviewmentioning

confidence: 99%

Optimal Multiobjective Control of Low-Voltage AC Microgrids: Power Flow Regulation and Compensation of Reactive Power and Unbalance

Brandão

Ferreira

Alonso

et al. 2020

IEEE Trans. Smart Grid

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show abstract

“…For instance, in [11], a centralised optimisation approach involving an adaptive power factor control and coordinated voltage control to reactive power management is proposed. In [12], a method is introduced to mitigate reactive power and current unbalance while DER are set to have a constant PQ control. In [13], a control strategy based on a multiagent system for voltage regulation in a distributed network with high DER penetration is proposed.…”

Section: Mandatory Reactive Power Provision By Bilateral Contractsmentioning

confidence: 99%

Optimal Microgrid–Interactive Reactive Power Management for Day–Ahead Operation

et al. 2021

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The replacement of conventional generation sources by DER creates the need to carefully manage the reactive power maintaining the power system safe operation. The principal trend is to increase the DER volume connected to the distribution network in the coming years. Therefore, the microgrid represents an alternative to offer reactive power management due to excellent controllability features embedded in the DER, which enable effective interaction between the microgrid and the distribution network. This paper proposes a microgrid−iterative reactive power management approach of power-electronic converter based renewable technologies for day-ahead operation. It is designed to be a centralised control based on local measurements, which provides the optimal reactive power dispatch and minimise the total energy losses inside the microgrid and maintain the voltage profile within operational limits. The proposed optimal-centralised control is contrasted against seven local reactive power controls using a techno-economic approach considering the steady−state voltage profile, the energy losses, and the reactive power costs as performance metrics. Three different reactive power pricing are proposed. The numerical results demonstrate the optimal microgrid−interactive reactive power management is the most suitable techno-economic reactive power control for the day−ahead operation.

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“…Nonlinear loads, such as switching power supplies, introduce harmonics into system voltage and current, and single-phase loads can cause voltage and current imbalances between the three phases of the network. Thus, the recent proliferation of nonlinear and single-phase loads in microgrids has created difficult challenges in maintaining the power quality of these networks [2].…”

Section: Introductionmentioning

confidence: 99%

Unbalanced Current Sharing Control in Islanded Low Voltage Microgrids

2018

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This paper reports a new control strategy to improve sharing of unbalanced currents in islanded LV microgrids. This technique provides fast and effective sharing of positive-, negative- and zero-sequence currents, and is the first example of zero-sequence current sharing in the literature. The controllers are designed in the stationary frame. The control structure consists of four loops: (1) the current controller; (2) the voltage controller; (3) the droop controller and the (4) negative and zero sequence current controllers. The output current is considered unknown for the controller and is added to the control system as a disturbance. The proposed controller features a high gain in fundamental and harmonic frequencies, hence a good voltage quality is obtained in the presence of unbalanced and nonlinear loads. To this aim, a proportional-resonant (PR) controller is adopted as the current controller. By using a multi-resonant controller as current controller, a unified control structure is obtained which is suitable for both grid-connected and islanded modes. The voltage controller is designed using a resonant controller so that the voltage can have low VUF and THD in the presence of unbalanced and nonlinear loads. Furthermore, in this paper, the droop method is applied to the control structure to share real and reactive powers. Simulation studies show that the conventional droop method cannot share the oscillatory part of the output power that is due to the presence of unbalanced loads in the microgrid. This paper relies on using zero and negative sequence virtual impedance controller to share the oscillatory part of output power. By using zero-sequence virtual impedance controller (ZSVIC) and negative-sequence virtual impedance controller (NSVIC), the zero and negative sequence currents in the microgrid are controlled and shared effectively. By compensating zero- and negative-sequence currents locally, the flow of these currents in the microgrid is minimized, and the overall power quality of the islanded LV microgrid is improved.

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A three-phase community microgrid comprised of single-phase energy resources with an uneven scattering amongst phases

Cited by 17 publications

References 40 publications

Optimal Multiobjective Control of Low-Voltage AC Microgrids: Power Flow Regulation and Compensation of Reactive Power and Unbalance

Optimal Multiobjective Control of Low-Voltage AC Microgrids: Power Flow Regulation and Compensation of Reactive Power and Unbalance

Optimal Microgrid–Interactive Reactive Power Management for Day–Ahead Operation

Unbalanced Current Sharing Control in Islanded Low Voltage Microgrids

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