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In recent years, community microgrids have expanded their power systems with many aims. One of the most important goals of microgrids is to increase resiliency. The main objective of this paper is to develop effective planning tools for community microgrids within electrical distribution networks, with a specific focus on ensuring the provision of critical loads during natural disasters. Additionally, this paper emphasized emphasises long-term planning considerations by using DIgSILENT 15.2 tools. The primary goal of this issue is to create the best planning tools for community microgrids in order to increase the network's resilience to natural disasters, with a focus on important loads like hospitals and hotels. Also, the second goal is an optimization that seeks to reduce overall expenses. Finally, we'll talk about how to get two results: one is to choose a few microgrid-based loads to link to the electrical distribution network, and the other is to show that each microgrid has the power needed to support both its local loads and the system's vital loads in the event of a natural disaster. In this paper, the use of community microgrids for energy access against natural disasters in Indonesia is investigated by considering the case study of microgrids on Lombok Island. The study results, using the proposed framework, show that the presence of a microgrid structure in the distribution network expansion planning helps to improve operating conditions and supply critical loads in natural disasters. [ABSTRACT FROM AUTHOR]

To enhance the efficiency of a port microgrid, this paper proposes an energy management method and a topology construction mechanism considering the convergence rate and information transmission distances, respectively. Firstly, a distributed fixed-time energy management method is proposed to solve an energy management problem in a known time and guarantee the efficiency of the port microgrid. Secondly, to address the challenge of heterogeneous devices with multiple communication protocols, information exchange between different devices is facilitated through a polymorphic network. To obtain a connected communication topology that can ensure the implementation of the distributed energy management method, a connected networking mechanism is proposed. This mechanism minimizes the total communication distance to reduce the effect of the information transmission distance on communication effectiveness. Finally, the effectiveness of both algorithms is demonstrated by simulation, and the advantages of the distributed fixed-time energy management method on the convergence rate are reflected through a comparison with other methods. [ABSTRACT FROM AUTHOR]

Extreme weather conditions and natural disasters (ND) are the main causes of power outages in the electric grid. It is necessary to strengthen the electrical power system's resilience during these catastrophic occurrences, and microgrids may be seen as the best way to achieve this goal. In this paper, two different energy system scenarios were proposed for increasing the resiliency of the electric power system during random outages. In the first scenario, a diesel generator (DG) was used to deliver energy to key loads during grid disruptions, in conjunction with a utility electric grid (UEG) and local electric load (ELL). A grid-connected ad hoc microgrid (MG) with a photovoltaic (PV) system, a battery energy storage (BES) system, and local electric loads made up the second scenario. The PV system and the BES system were used to supply the key loads with electricity during the outage. The major aim of this research was to compare the two resilient-based systems from the perspectives of technology, economics, and the environment. Given that it requires greater resilience than the other loads during severe weather, a hospital load on Indonesia's Lombok Island was chosen as the critical load. The objective function considers the system's predefined constraints to reduce the overall net present cost (NPC) and the cost of energy in order to maximize the system resilience (COE). The Optimization of Multiple Energy Resources (HOMER) Grid simulated a 3-day outage in August 2021, and the results demonstrated that the resiliency enhancement for both scenarios was nearly identical. The first scenario resulted in fewer CO2 emissions; however, the second scenario delivered lower operating costs and COE. The simulation's findings showed that system 1 created an annual emission of 216.902 kg/yr while system 2 only produced an emission of 63.292 kg/yr. This study shows that since RES-based MGs don't burn fossil fuels to generate power, they are more environmentally friendly resources. [ABSTRACT FROM AUTHOR]

Voltage–current (V–I) droop control is becoming a promising alternative to achieve proper power sharing among the parallel-operated voltage-sourced inverters (VSIs). Compared with the conventional droop control, this method has a simpler structure and a better dynamic performance because it saves the power loop (including the low-pass filters). However, due to the absence of the power loop related to the system frequency, the synchronization of VSIs becomes an intractable issue. To tackle this, a communication-free algorithm to synchronize and control the VSIs is proposed. Initially, the principle of V–I droop control is presented straightforwardly based on the virtual impedance. Then, a synchronization algorithm is incorporated into the V–I droop controller for accurate power sharing. This algorithm adaptively adjusts the phase step of each VSI according to the phase differences between VSI and the ac bus. In this way, the phase differences of each VSI to the ac bus eventually converge to an identical value, thus realizing the synchronization of VSIs. A detailed parameter design method is also implemented considering both system stability and power quality. Finally, the proposed strategy is validated experimentally using a three-parallel-VSIs system. [ABSTRACT FROM AUTHOR]

Nonlinear dynamical systems such as weakly coupled oscillators are an interesting approach to be adopted for the regulation of power inverters inside microgrids. Aiming at the synchronization and load sharing in islanded mirogrid, this article is inspired by oscillator synchronization property to propose a Hopf oscillator controller for the single-phase inverters. The Hopf oscillator dynamic equations are used for providing the inverter's frequency and amplitude voltage references, which lead to a robust nonlinear droop behavior for driving the system without using communications. The Hopf oscillator provides better sharing of the load between inverters with higher robustness, less harmonic distortion, and faster time response of the associated limit cycle than the achieved by the other approach made with a Van der Pol oscillator. In addition, global asymptotic synchronization of system is proven by Lyapunov approach. Simulation results of a system composed by paralleled inverters are provided and compared with a Van der Pol oscillator approach reported in literature. Experimental results are also provided to prove the Hopf oscillator based controller under different circumstances. [ABSTRACT FROM AUTHOR]

A dynamic consensus algorithm (DCA)-based coordinated secondary control with an autonomous current-sharing control strategy is proposed in this paper for balancing the discharge rate of energy storage systems (ESSs) in an islanded ac microgrid. The DCA is applied for information sharing between distributed generation (DG) units to regulate the output power of DGs according to the ESS capacities and state-of-charge (SoC). Power regulation is achieved by adjusting the virtual resistances of voltage-controlled inverters with an autonomous current-sharing controller. Compared with existing methods, the proposed approach can provide higher system reliability, expandability, and flexibility due to its distributed control architecture. The proposed controller can effectively prevent operation failure caused by over-current and unintentional outage of DGs by means of balanced discharge rate control. It can also provide fast response and accurate current sharing performance. A generalizable linearized state-space model for ${n}$ -DG network in the ${z}$ -domain is also derived and proposed in this paper; the model includes electrical, controller, and communication parts. The system stability and parameter sensitivity have been analyzed based on this model. To verify the effectiveness of the proposed control approach, this paper presents simulation results from a ten-node network and a comparison between experimental results obtained from the conventional power sharing control and the DCA-based SoC coordinated control in a setup with three 2.2 kW DG units. [ABSTRACT FROM AUTHOR]

The papers in this special section offer a collection of new and original papers that cover different aspects from architecture, scheme design, control strategy, optimization, application and deployment of energy Internet systems. [ABSTRACT FROM AUTHOR]

Hybrid photovoltaic (PV)-battery-hydropower microgrids (MGs) can be considered to enhance electricity accessibility and availability in remote areas. However, the coexistence of different renewable-energy sources with different inertias and control strategies may affect system stability. In this paper, a hierarchical controller for a hybrid PV-battery-hydropower MG is proposed in order to achieve the parallel operation of the hydropower and PV-battery system with different rates and to guarantee power sharing performance among PV voltage-controlled inverters, while the required power to the hydropower-based local grid is supplied. In this case, the PV-battery system will operate as a $PQ$ bus to inject the desired active and reactive powers to the local grid, while the hydropower station will act as a slack bus which maintains its voltage amplitude and frequency. An integrated small-signal state-space model is derived to analyze the system stability of the hybrid MG. The simulation results show system frequency and voltage stability for a hybrid MG demonstration which includes the 2-MWp PV installations, a 15.2-MWh battery system, and a 12.8-MVA hydropower plant. The experimental results on a small-scale laboratory prototype verify the validity of the theoretical analysis and proposed control strategy. [ABSTRACT FROM PUBLISHER]

The dynamic performance of the local control of single-phase voltage source inverters (VSIs) can be degraded when supplying to nonlinear loads (NLLs) in microgrids. When this control is based on the droop principles, a proper calculation of the active and reactive averaged powers (P–Q) is essential for a proficient dynamic response against abrupt NLL changes. In this work, a VSI supplying to an NLL was studied, focusing the attention on the P–Q calculation stage. This stage first generated the direct and in-quadrature signals from the measured load current through a second-order generalized integrator (SOGI). Then, the instantaneous power quantities were obtained by multiplying each filtered current by the output voltage, and filtered later by utilizing a SOGI to acquire the averaged P–Q parameters. The proposed algorithm was compared with previous proposals, while keeping the active power steady-state ripple constant, which resulted in a faster calculation of the averaged active power. In this case, the steady-state averaged reactive power presented less ripple than the best proposal to which it was compared. When reducing the velocity of the proposed algorithm for the active power, it also showed a reduction in its steady-state ripple. Simulations, hardware-in-the-loop, and experimental tests were carried out to verify the effectiveness of the proposal. [ABSTRACT FROM AUTHOR]

High penetration level of PV sources in low-voltage distribution network (LVDN) leads to the voltage fluctuation problem, which may limit the maximal PV power generation due to the security issues of distribution networks. This paper proposes a distributed voltage regulation method by sharing the power of distributed heterogeneous battery energy storage systems (BESS) properly. With the help of local voltage/power droop controller, BESS absorbs power from LVDN when nodal voltage is above the upper limit, and injects power to LVDN when nodal voltage is lower than the bottom limit. The voltage regulation burden is properly shared among BESSs not only according to the capacities but also the state of charge (SoC). Moreover, even the communication network among BESSs is time-varying, the proposed method is able to regulate nodal voltages. For an extreme scenario with communication failures, the proposed method can also guarantee the voltage regulation and power sharing locally. Furthermore, a dynamic event-triggered communication strategy is designed for BESS aiming at reducing communication burden. Four simulation cases are designed on MATLAB/Simulink to validate the effectiveness of the proposed method. The results show that the proposed method is capable of maintaining nodal voltages within the normal range, and achieves the proportional regulation and SoC balance among different BESS with reduced communications. • Our research focuses on distributed voltage regulation in LVDN. • A distributed event-triggered control method is proposed for BESS to share voltage regulation burden. • BESS parameter differences, time-varying communication networks and communication link failures are investigated. • A real-world LVDN validates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]