Fully Distributed Hierarchical Control of Parallel Grid-Supporting Inverters in Islanded AC Microgrids

Abstract

In this paper, a fully distributed hierarchical control strategy is proposed for operating networked gridsupporting inverters (GSIs) in islanded ac microgrids (MGs). The primary control level implements frequency and voltage control of an ac MG through a cascaded structure, consisting of a droop control loop, a virtual impedance control loop, a mixed H 2 /H ∞-based voltage control loop, and a sliding-mode-control-based current loop. Compared to conventional proportional-plus-integral-based cascaded control, the proposed cascaded control does not require a precise model for the GSI system. The proposed secondary control level implements distributed-consensus-based economic automatic generation control and distributed automatic voltage control, which integrates the conventional secondary control and tertiary control into a single control level by bridging a gap between traditional secondary control and tertiary control. Simulation results demonstrate the effectiveness of the proposed hierarchical control strategy. Index Terms-Automatic voltage control (AVC), distributed consensus, distributed hierarchical control, droop control, economic automatic generation control (EAGC), grid-supporting inverter (GSI).

Distributed Multienergy Coordination of Multimicrogrids With Biogas-Solar-Wind Renewables

“…Several recent representative literatures have studied the operation optimization of multi-microgrid system from various aspects, including optimal power dispatch [2]- [4], optimal voltage and frequency management [5], energy trading mechanism design [6]- [8], optimal power flow [9], [10], etc. With the increasing utilization of gas-fired and other distributed generation, especially co-and trigeneration, the electric microgrid gradually transforms towards a multi-energy microgrid.…”

“…The studies in [4], [20], [21] assumed a single centralized operator to coordinate supply and demand of all the microgrids, which may lead to privacy violations as well as computation and communication bottlenecks. The second one is the distributed approach in which distributed algorithms such as alternating directions method of multipliers algorithm [2], [3], Lagrangian relaxation [6], model predictive control [18], [19], consensus-algorithms [5], [23] have been proposed to solve this multi-microgrid scheduling problem. Nevertheless, existing distributed approaches have only been verified for their feasibility and effectiveness in operational optimization of systems employing only one form of energy, and few works have attempted to involve multiple energy carriers, such as electricity, heat and gas.…”

Virtual Inertia-Based Control Strategy of Two-Stage Photovoltaic Inverters for Frequency Support in Islanded Micro-Grid

“…can be calculated based on the aggregated power of the PV system and the total load demand in a centralized or distributed manner, for example, through an energy management controller or consensus algorithms [38,39]. Based on the overall available generation, _ G total p and the load demand…”

“…T e and D e are defined as the power control coefficients, which are the positive constants. The initial power set-point p set_0 can be calculated based on the aggregated power of the PV system and the total load demand in a centralized or distributed manner, for example, through an energy management controller or consensus algorithms [38,39]. Based on the overall available generation, p G_total and the load demand p L_total of the islanded micro-grid, the utilization level, β, can be calculated as β = p L_total /p G_total .…”

Modelagem de Pequenos Sinais para o Paralelismo de Inversores Utilizando Controle Hierárquico

“…Neste trabalho utiliza-se uma resistência virtual, apesar de usualmente, em redes de baixa de tensão, as impedâncias de linha já apresentarem característica resistiva [12]. A implementação é realizada a partir da realimentação da corrente do indutor do filtro de saída, conforme: (5) onde v * é a referência de tensão gerada pelo controlador droop, vref é a referência de tensão após a impedância virtual, iL é a corrente do indutor de saída e Zv(s) é a impedância virtual.…”