Coordinated voltage control in distribution grids with LTE based communication infrastructure

Ferreira

et al. 2020

IEEE Trans. Smart Grid

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.

Section: Stability Analysismentioning

confidence: 99%

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

Ferreira

et al. 2020

IEEE Trans. Smart Grid

“…8(a) the system is assessed considering Td varying from 1/600 s up to 1/6 s, while considering T = 1/60 s. Note that the system can be considered stable for all the considered values of Td, since all poles lie within the unit circle. Hence, by considering that modern communication systems applied to such scenario could present maximum latency of about 100 ms [34], the PBC operation would not impair in instability. The drawback of having slower transmission times for the data flowing from DERs to MC (i.e., higher Td); however, is that the poles of the system tend to move towards the positive real axis, becoming more dominant and consequently presenting more influence on system stability.…”

Section: B Stability Analysismentioning

confidence: 99%

Coordinated Control of Distributed Three- and Single-Phase Inverters Connected to Three-Phase Three-Wire Microgrids

Araujo

IEEE J. Emerg. Sel. Topics Power Electron.

et al. 2020

This paper explores the coordinated strategy named Power-Based Control to properly coordinate gridtied single-and three-phase distributed energy resources in three-phase three-wire microgrids. By means of a narrowband, low data rate communication, such strategy accommodates current-and voltage-controlled distributed inverters providing proportional sharing of active, reactive and unbalance (negative-sequence) power terms, also offering dispatchable power flow and high power quality at the microgrid's point of common coupling. Regarding the current unbalance compensation, a particular case considering two distributed single-phase inverters is discussed through mathematical analysis in terms of balanced and unbalanced power terms, and experimental results on which the Power-Based Control is applied to demonstrate that this strategy corroborates with Steinmetz principle. Finally, the complete strategy is evaluated in simulation considering the model of a real urban power distribution grid under typical operational conditions.

“…In addition, as evaluated in [32], DNP3 can perform data transmission with delays from 3 to 100 ms, depending on the type of message to be sent and the distances of the communicating nodes. This also encompasses expected latencies for data transmissions within MGs, of up to 100 ms, as discussed in [33]. Thus, in brief, this protocol should be a suitable solution for implementation of cooperative strategies, especially for approaches requiring a centralized controller, which could monitor and manipulate inverter's data just as already done by punctual utility related applications.…”

Section: B Dnp3 Protocolmentioning

confidence: 99%

Considerations on Communication Infrastructures for Cooperative Operation of Smart Inverters

Afonso

2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC)

et al. 2019

The presence of distributed generation systems spread over low-voltage electrical networks is boosting the development of control methodologies aiming at coordinating and cooperatively managing the existing smart inverters. Although low-bandwidth data transmission links are constantly described to be required for a considerable number of centralized and decentralized control methodologies, there is a gap in literature concerning the plain understanding of the features of the related communication protocols available for such application. Thus, this paper brings considerations on some of the most relevant communication protocols that can be applied to the cooperative control of multiple smart inverters, taking into account the recent updates on interoperability requirements recommended by the IEEE 1547-2018 standard. The communication infrastructure, topology and features of a low-bandwidth data transmission link are discussed in this paper focusing on the SunSpec, DNP3 and SEP2 protocols. Yet, some critical comments are made regarding the practical interoperability of commercial inverters, also bordering cyber security matters.