Dynamics and control of microgrids as a resiliency source

Lee, Lung-An; Liu, Chen‐Ching; Xu, Yin; Schneider, Kevin P.; Tuffner, Francis K.; Mo, Kefei; Ton, Dan

doi:10.1002/2050-7038.12610

Cited by 11 publications

(16 citation statements)

References 25 publications

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“…where, dynamic real and reactive power control inputs and outputs are (p and q) and (u α and u β ), respectively. Since both the control inputs in (17) are coupled in P and Q states, by using voltage modulation theory [34], the dynamics of ( 17) can be simplified as (18) to define new voltage modulated control inputs:…”

Section: Dpc and Pvmt-based Pv-vsi Modellingmentioning

confidence: 99%

“…Since in the aforementioned methods, Park's transformation has been used during abc to dq transformation, there is a need for phase angle extraction from grid voltages to ensure dq axes currents and grid voltages are in phase with each other [18]. Phaselocked loop (PLL) systems are commonly used for the extraction of grid voltage phase angles, based on arctangent functions [19].…”

Section: Introductionmentioning

confidence: 99%

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Fuzzy Logic-Based Direct Power Control Method for PV Inverter of Grid-Tied AC Microgrid without Phase-Locked Loop

et al. 2021

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A voltage source inverter (VSI) is the key component of grid-tied AC Microgrid (MG) which requires a fast response, and stable, robust controllers to ensure efficient operation. In this paper, a fuzzy logic controller (FLC)-based direct power control (DPC) method for photovoltaic (PV) VSI was proposed, which was modelled by modulating MG’s point of common coupling (PCC) voltage. This paper also introduces a modified grid synchronization method through the direct power calculation of PCC voltage and current, instead of using a conventional phase-locked loop (PLL) system. FLC is used to minimize the errors between the calculated and reference powers to generate the required control signals for the VSI through sinusoidal pulse width modulation (SPWM). The proposed FLC-based DPC (FLDPC) method has shown better tracking performance with less computational time, compared with the conventional MG power control methods, due to the elimination of PLL and the use of a single power control loop. In addition, due to the use of FLC, the proposed FLDPC exhibited negligible steady-state oscillations in the output power of MG’s PV-VSI. The proposed FLDPC method performance was validated by conducting real-time simulations through real time digital simulator (RTDS). The results have demonstrated that the proposed FLDPC method has a better reference power tracking time of 0.03 s along with reduction in power ripples and less current total harmonic distortion (THD) of 1.59%.

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Section: Dpc and Pvmt-based Pv-vsi Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fuzzy Logic-Based Direct Power Control Method for PV Inverter of Grid-Tied AC Microgrid without Phase-Locked Loop

et al. 2021

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“…Based on the authors’ prior work [30], PID control is found to be practical through a field test on a campus microgrid system. In this study, however, the overshoot is not critical (less than 5% under a 45% heavy load pick up event).…”

Section: Microgrid Control Schemementioning

confidence: 99%

“…To maximize the restoration capability and better respond to the dynamics, based on the authors' prior work [30], DGs must share, by the same ratio, the real and reactive power output to the respective rated capacity of each DG unit. The microgrid needs to have the capability to regulate frequency and voltage to synchronize with the utility and/or other microgrids.…”

Section: Microgrid Control Schemementioning

confidence: 99%

Critical values of cyber parameters in a dynamic microgrid system

Lee

Liu

Wang

et al. 2021

IET Generation Trans & Dist

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An islanded microgrid is cyber-physical system, and the control relies on the communication system significantly. Improper parameters of the cyber system can result in instability of a microgrid system. To evaluate the impact of a networked control system on control performance, a cyber model is developed to represent data acquisition periods and communication delays. Simplification of the networked control system model is proposed to enhance the computational performance, making the analytical method applicable for large-scale systems. Based on the analysis, a two-dimensional stability region of a microgrid in the space of cyber parameters can be obtained. To validate the proposed method, a microgrid control scheme is proposed for power dispatch and regulation based on the droop and proportional-integral (PI) feedback control. The analytical method is compared to the time-domain simulation, and it is shown that the stability regions are nearly identical. The critical values of cyber parameters are determined based on the analytical results. The proposed control strategy with the given cyber parameters is validated for transient stability following dynamic events. Simulation results indicate that the design of a microgrid as a cyber-physical system needs to be guided by critical values for cyber parameters to prevent system instability.

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“…In Reference 24, for a grid‐connected MG, new control and power management strategy were presented. All these methods are based on dq CCT where phase angle from the grid voltages need to be extracted accurately for Park transformation to ensure grid voltage and dq axes currents are in phase 25 . Most commonly used technique nowadays for phase angle extraction of the grid voltage or grid synchronization is phase‐locked loop (PLL) 26,27 .…”

Section: Introductionmentioning

confidence: 99%

An improved power control strategy for grid‐connected hybrid microgrid without park transformation and phase‐locked loop system

Ahmad

Mekhilef

Mokhlis

2021

Int Trans Electr Energ Syst

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Summary Voltage source converters are important elements of grid‐connected microgrid, as these integrate distribution generators of microgrid with utility grid. Often due to lack of efficient and flexible control, these converters do not perform as per expectations. Many control methods based on dq current control theory had been developed for grid‐connected microgrids inverters to control power flow between microgrid and grid. However, all these controllers used phase locked loop systems for grid synchronization purposes, which possess slow dynamics and transient response. To overcome these issues, in this article, an improved real and reactive power control method for grid‐connected hybrid microgrid's bidirectional voltage source converter is proposed which is based on the dq current control theory without using phase locked loop system and Park transformation. The proposed power controller has possessed better dynamic performance compared with the conventional power controllers consisted of phase locked loop system. In addition, due to the elimination of phase locked loop system and park transformation not only the computational burden is reduced with the implementation of the proposed power controller, but also steady state performance is enhanced. The control hardware‐in‐loop real time simulation is carried out using real time digital simulator to validate the performance of the proposed power controller during transient state, steady state and power transfer mode by modeling a grid‐connected hybrid microgrid. From the simulation results, it has been observed that the settling time has improved to 0.08 second compared to 0.15 second of conventional controller, power ripples are significantly reduced, and total harmonic distortion of converter output current obtained is 2.226%.

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Dynamics and control of microgrids as a resiliency source

Cited by 11 publications

References 25 publications

Fuzzy Logic-Based Direct Power Control Method for PV Inverter of Grid-Tied AC Microgrid without Phase-Locked Loop

Fuzzy Logic-Based Direct Power Control Method for PV Inverter of Grid-Tied AC Microgrid without Phase-Locked Loop

Critical values of cyber parameters in a dynamic microgrid system

An improved power control strategy for grid‐connected hybrid microgrid without park transformation and phase‐locked loop system

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