Power System Harmonics Study for Unbalanced Microgrid System with PV Sources and Nonlinear Loads

Liu, Zhanhe; Xu, Xufeng; Abdelsalam, Hany A.; Makram, Elham B.

doi:10.4236/jpee.2015.35004

Cited by 14 publications

(7 citation statements)

References 18 publications

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“…When compared to AC MGs, within DC MG, no synchronization is required for its connected DERs and loads, and no skin effect or power factor losses. Even though DC MG might seem exceedingly advantageous, it introduces challenges regarding the designing of an effective protection system [17][18][19]. Moreover, analyzing the stability of AC systems is more established than that of the DC ones, which is still under investigation.…”

Section: Microgrid Types and Control Techniquesmentioning

confidence: 99%

Impact of Information and Communication Technology Limitations on Microgrid Operation

et al. 2019

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This paper provides an extensive review of the conducted research regarding various microgrids (MGs) control techniques and the impact of Information Communication Technology (ICT) degradation on MGs performance and control. Additionally, this paper sheds the light on the research gaps and challenges that are to be explored regarding ICT intrinsic-limitations impact on MGs operations and enhancing MGs control. Based on this assessment, it offers future prospects regarding the impact of ICT latencies on MGs and, consequently, on the smart grid. Finally, this paper introduces a case study to show the significance and examine the effect of wireless communication technologies latency on the converters and the DC bus voltage of a centralized controlled DC MG. A DC microgrid with its communication-based control scheme was modeled to achieve this goal. The MATLAB simulation results show that the latency impact may be severe on the converter switches and the DC bus voltage. Additionally, the results show that the latency impact varies depending on the design of the MG and its operational conditions before the latency occurs.

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Section: Microgrid Types and Control Techniquesmentioning

confidence: 99%

Impact of Information and Communication Technology Limitations on Microgrid Operation

et al. 2019

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“…This is the reason, most of the DERs and ESSs are DC systems [5]. The main known challenges to date are around the design of efficient protection systems [6][7][8]. As such, the hybrid system has been developed with consideration of the advantages of both AC and DC systems.…”

Section: Introductionmentioning

confidence: 99%

Analysis of LoRa Transmission Delay on Dynamic Performance of Standalone DC Microgrids

Ndukwe¹,

Iqbal²,

Khan³

et al. 2022

JEPT

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One important aspect toward proper and stable functioning of a communication-based controlled microgrid is data transmission. Consequently, an analysis of the effect of data transmission delay is of significance for any chosen communication protocol. This paper focuses on the effect of employing LoRa for data transfer at the secondary control level of a standalone DC microgrid. It analyses the effect of LoRa transmission delay on the dynamic performance of DC microgrids. This paper simulates a community DC microgrid that operates in three modes: PV mode, battery mode and generator mode. This microgrid operates as a centralized communication-based controlled microgrid, with the secondary control level operating as an event-driven level. The system incorporates a hierarchical system where data is transferred between the various distributed energy resources (DERs) local controllers and the microgrid central controller (MGCC). Simulations for three scenarios are presented. In the first scenario, the microgrid is designed and simulated without a communication delay to observe the system behavior. Then LoRa transmission delay is calculated for the various signals transferred between the MGCC and the local controllers. This delay is introduced into the simulation as transport delays and the system exhibits a level of stability degradation. Subsequently, a time delay compensation system is incorporated into the system for more robust operation. The delay compensation is applied in two simulation scenarios. In the first scenario, the system inductor (L) and capacitor (C) components are re-calculated, and the system is re-simulated to get a stable system even with the applied communication delay. In the second scenario, the proportional integrator (PI) controller in the microgrid central controller is re-designed to a more robust form to compensate for the delay caused by the LoRa transmission. The results obtained from the two modified simulations realize a stable DC microgrid. This system modification allows for system stability again, similar to the simulation when the microgrid operated without any communication delay. This, therefore, demonstrates that with proper system design and implementation, low bandwidth communication systems such as LoRa can be effectively employed for data transfer in event-driven communication-based controlled DC microgrids.

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“…As per [2], India has targeted to generate 100 GW of solar power by 2022. To recap, power generation in India was at 3 GW in 2014 but had reached an installed solar capacity of 31.1 GW prises nonlinear loads such as variable speed drives, compact florescent light (CFL) and so on as a source of harmonics, the addition of a grid-tied PV system will further increase the harmonic level in the grid [10,11]. Moreover, a low irradiation level worsens the issues of harmonics [12,13].…”

Section: Introductionmentioning

confidence: 99%

A random carrier frequency PWM technique with a narrowband for a grid-connected solar inverter

et al. 2020

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The quality of power is always a concern for the high penetration of a grid-connected solar photovoltaic (PV) system due to the variation in solar irradiation and the temperature change of solar output, which in turn varies the fundamental component of power delivered to the grid. A solar source requires an inverter interface to supply the AC load as well as for the grid interconnection. Any reduction in the fundamental component generated by solar PV at a lower irradiation level or at hightemperature results in increasing %THD at the output of inverter for a given fixed switching frequency since harmonics due to PWM technique is comparable with the fundamental component. The selection of high-fixed-switching-frequency PWM reduces harmonics but increases the stress on switches and switching losses. It also suffers from issues of harmonics at carrier frequency and its sideband at multiples of switching frequency that causes acoustic noise and EMI. The random frequency PWM (Random PWM) method overcomes these issues presented by the fixed-frequency PWM method. However, a wide band of Random PWM makes the inverter filter design difficult and causes resonance in the distribution system. In addition, asymmetry in the carrier wave introduces even-order harmonics in the line current. Hence, this paper proposes a narrowband random frequency PWM method to reduce sideband harmonics, lower-order harmonics, even-order harmonics and a total harmonic distortion (THD) for a solar-based grid-connected inverter. Simulation results present a satisfactory performance of the proposed control technique for a steady-state and transient results. Experimental validation of the same is carried out on the OPAL-RT OP4500-based laboratory prototype of a 2-kVA inverter which depicts reduction in harmonics and hence improvement in power quality. KeywordsGrid-connected inverter • Harmonics • Linear control • Random PWM • Solar inverter B Rajendrasinh Jadeja

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Power System Harmonics Study for Unbalanced Microgrid System with PV Sources and Nonlinear Loads

Cited by 14 publications

References 18 publications

Impact of Information and Communication Technology Limitations on Microgrid Operation

Impact of Information and Communication Technology Limitations on Microgrid Operation

Analysis of LoRa Transmission Delay on Dynamic Performance of Standalone DC Microgrids

A random carrier frequency PWM technique with a narrowband for a grid-connected solar inverter

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