Analysis of the Effect of Clock Drifts on Frequency Regulation and Power Sharing in Inverter-Based Islanded Microgrids

Martí, Pau; Torres-Martínez, Javier; Rosero, Carlos; Velasco, Manel; Miret, Jaume; Castilla, Miguel

doi:10.1109/tpel.2018.2805368

Cited by 23 publications

(30 citation statements)

References 37 publications

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“…It is convenient to partition the universal time axis into a sequence of nonoverlapping time slots [νT 0 , (ν + 1)T 0 ). In practice, α j differs from 1 by a very small amount, on the order of a few parts per million (ppm) [26], and it is therefore safe to assume that each time slot contains a single clock tick t j [ν] as shown in Fig. 2.…”

Section: System Model and Problem Statement A Network Setup And mentioning

confidence: 99%

A Distributed Pulse-Based Synchronization Protocol for Half-Duplex D2D Communications

Karatalay

Psaromiligkos

Champagne

et al. 2021

IEEE Open J. Commun. Soc.

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In distributed device-to-device (D2D) communications, no common reference time is available and the devices must employ distributed synchronization techniques. In this context, pulse-based synchronization, which can be implemented by distributed phase-locked loops is preferred due to its scalability. Several factors degrade the performance of pulse-based synchronization, such as duplexing scheme, clock skew and propagation delays. Furthermore, in distributed networks, devices should be aware of the synchronization status of others in order to initiate data communications. To address these prevailing issues, we first introduce a half-duplex timing-advance synchronization algorithm wherein each device alternates between being a transmitter and receiver in their exchange of synchronization pulses at each clock period. Based on this algorithm, we propose a novel fully-distributed pulse-based synchronization protocol for half-duplex D2D communications in 5G wireless networks. The protocol allows participating devices to become aware of the global synchronization status, so that they can complete the synchronization process ideally at the same time and proceed to data communication. In simulation experiments over multi-path frequency selective channels, the proposed synchronization protocol is shown to outperform a benchmark approach from the recent literature over a wide range of conditions, e.g., clock skew, number of devices, and network topology.

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Section: System Model and Problem Statement A Network Setup And mentioning

confidence: 99%

A Distributed Pulse-Based Synchronization Protocol for Half-Duplex D2D Communications

Karatalay

Psaromiligkos

Champagne

et al. 2021

IEEE Open J. Commun. Soc.

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“…From [33], the transfer function of the inverter

{\overset{p}{true}}_{i} false(s false) / {\overset{ω}{true}}_{i} false(s false) = {\overset{g}{true}}_{i} false(s false)

can be written as:

{\overset{g}{true}}_{i} (s) = \frac{3 ω_{o} L_{i} V_{o}^{2}}{({((), L_{i} s + R_{i})}^{2} + {((), ω_{o} L_{i})}^{2}) s}

where

R_{i}

and

ω_{o} L_{i}

are the real and imaginary impedances seen by the i th inverter, and

V_{o}

are the amplitudes of the AC bus voltage. The nominal value of the real and imaginary impedances seen by each inverter are calculated using the data shown in Table 1, being 10 mH the virtual output impedance of each inverter [27, 28]. These impedances are presented in Table 2.…”

Section: Control Designmentioning

confidence: 99%

A distributed control for accurate active‐power sharing in islanded microgrids subject to clock drifts

Alfaro

Castilla

Camacho

et al. 2021

IET Power Electronics

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Inverters‐based islanded microgrids are operated by local digital signal processors, driven by their own local clocks. These local clocks have drifts affecting the clock signals which are used to control the inverters in real time. In this scenario, a steady‐state deviation is observed in active power sharing, degrading the microgrid performance. This paper presents a new control scheme that improves the microgrid performance by cancelling the active power sharing error due to clock drifts. The study includes a theoretical stability analysis and a design procedure of the control parameters based on the dynamic characteristics. Finally, selected experimental results are obtained in a laboratory microgrid with four inverters. In this setup, each inverter was equipped with its digital signal processor with drifting local clock.

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“…Whereas the centralized and distributed methods require exchange of information between units through a communication network, in the fully decentralized approach the restoration process of voltage and frequency is carried out by multiple secondary controllers operating locally at each distributed generator (DG) without data sharing with other DGs [27], [28]. Communication-less control may provide some important advantages; however, these decentralized secondary control methods must overcome a variety of issues such as clock-drift [29], [30] to reach the maturity level of the centralized and distributed solutions. For our purposes, then, only the two secondary control categories based on communication will be included in this investigation.…”

Section: B Secondary Levelmentioning

confidence: 99%

Communication Requirements in Microgrids: A Practical Survey

et al. 2020

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Progress in Microgrid (MG) research has evolved the MG concept from classical, purely MG power networks to more advanced power and communications networks. The communications infrastructure helps control and manage the unreliable power outputs that most standard power generation elements of the MG (e.g., wind turbines and photo-voltaic panels) deliver. Although communication technologies do offer certain advantages for sensing and control, they generate other complications due to packet loss and packet latency, among other transmission impairments. In this work, we discuss the impact of communications on MG performance, establishing the requirements of data exchanges and system response in the three levels of a hierarchical control approach: primary, secondary, and tertiary. With a focus on the secondary level-responsible for ensuring the restoration of electrical parameters-we identify standards, networking protocols, and communication technologies relevant for the interoperability of MGs and clusters of MGs, including both modes of operation: isolated and grid-connected. We review theoretical approaches and practical implementations that consider the effects of the communications network on the general performance of the MG. Moreover, we undertake an experimental analysis of the influence of wired and wireless communication networks on MG performance, revealing the importance of designing future smart control solutions more robust to communication degradation, especially if wireless technologies are integrated to provide scalable deployments. Aspects such as resilience, security, and interoperability are also shown to require continuing efforts in research and practical applications.

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Analysis of the Effect of Clock Drifts on Frequency Regulation and Power Sharing in Inverter-Based Islanded Microgrids

Cited by 23 publications

References 37 publications

A Distributed Pulse-Based Synchronization Protocol for Half-Duplex D2D Communications

A Distributed Pulse-Based Synchronization Protocol for Half-Duplex D2D Communications

A distributed control for accurate active‐power sharing in islanded microgrids subject to clock drifts

Communication Requirements in Microgrids: A Practical Survey

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