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Distributed generators are often integrated into the distribution system, resulting in the creation of an autonomous microgrid. However, distributed generators have less inertia than traditional synchronous generators, and they can cause the system frequency to become unstable. In addition, as more clusters are integrated into the distribution microgrid, frequency fluctuations rises. This report recommends a supercapacitor control strategy in order to resolve frequency fluctuations in the microgrid cluster. The new fractional-order supercapacitor controller has more freedoms than the conventional controller. In all cases, we found that the proposed strategy would be able to maintain the system's frequency.
Source link: https://doi.org/10.3390/en15145179
The reactive power-sharing issue is one of the major challenges in a grid-independence MG. The mismatch of feeder impedance and private load is affecting reactive power sharing. A mathematical formula is used to determine the equivalent impedance as a function of DG's total power production and the power fed to the feeder. Each feeder is based on the calculated equivalent impedance. DGs can be divided by virtual impedance and private loads, which allows accurate reactive power sharing among DGs.
Source link: https://doi.org/10.3389/fenrg.2022.946872
The optimal current distribution coefficient of the distributed energy unit is determined online by the double ascent optimization scheme in order to minimize distribution losses, based on the concave optimization principle. In real time, the most effective active power dispersion coefficient with the minimum distribution loss of the AC microgrid can be obtained with the standard reactive power distribution scheme. In addition, the efficient poweru2013voltage droop control and reactive power amplitude droop control are not appropriate for power distribution among DEUs, considering the high R/X ratio in the short-distance AC microgrid's high R/X ratio.
Source link: https://doi.org/10.3389/felec.2022.926865
However, the grid's stable operation is seriously impaired by system frequency and active power oscillation triggered by power fluctuations and grid faults. According to simulation and experimental results, the enhanced VSG algorithm developed in this study has a significant effect on power-u2010frequency oscillation suppression, decreases active power and frequency overshoot, shortens the adjustment time, and increases system frequency stability active power.
Source link: https://doi.org/10.1049/rpg2.12461
paragrid with an improved energy management system This paper describes an enhanced energy management system for a residential AC microgrid. A photovoltaic array with hybrid energy storage, a battery, and a supercapacitor as a hybrid energy storage device, as well as apartments and electric vehicles in residential areas are divided into three specific components. The new EEMS is a hybrid control scheme that consists of two phases: a state machine control to ensure the battery's safe operation; and a operating mode for the highest operation of the SC. In addition, power loss is reduced during peak cloud phases by reducing the power error between the extracted power by the sources and the required equivalent; the increase in efficiency hits 9. 5%; power loss is minimized during passing cloud phases.
Source link: https://doi.org/10.3390/en13123268
In this paper, three phase parallel Voltage Source Inverters are developed for both design and hierarchical control. paraphrasedoutput loops and the virtual output impedance loops are the primary control of the primary control. The droop control and the virtual output impedance loops are both included in the primary control. This control level is intended to divide the active and reactive capability of the connected VSIs in order to prevent the undesirable circulating current and overload of the connected VSIs that are not connected.
Source link: https://doi.org/10.15598/aeee.v15i2.1912
Uncertain values of interconnecting cable impedances in an ac microgrid, negatively impact reactive power sharing accuracy is impacted by an ac microgrid's poor quality of interconnecting cable impedances. In the literature, several types of secondary controllers have been suggested, including linear proportional plus integral controllers to eliminate the difference in reactive power sharing imposed by conventional Eu2212Qdroop. The reference value of the PI controller is the average value of reactive powers supplied by the sources. When the PI controller is used to minimize the difference between reactive power measured by the source and reference value is used, the difference between the numerical sum of reactive powers supplied by the sources and the loads's reactive powers has a nonzero value. In such a way that each source's proportional value of reactive power equals its proportional value of reactive power, the PRPS controller modifies the droop gain of the E2112Qdroop control loop of each source. The proportional value of reactive power supplied by each source is the power when the equivalent output impedance of all sources is equal, as seen by the loaders. The proposed controller guarantees zero appreciation of the difference between the algebraic sum of reactive powers supplied by the sources and the load's reactive powers. Using a simplified order small-signal model, the effects of the new controller on the system's stability can be shown. With the assistance of roots locus plots, the effect of communication delay on the system's results is investigated.
Source link: https://doi.org/10.1016/j.egyr.2022.05.014
When the voltage and frequency support comes from the power-electronic-based inverters, it is essential to develop the DG's inverter's rejection ability against disturbances. This paper discusses a new distributed secondary frequency control system for islanded microgrids, in which the primary aim is to eliminate the frequency variation under droop control's improved disturbance rejection results. Unlike many traditional approaches that rely on a sophisticated control system, the latest one does not need model details due to the model-independent characteristic of active disturbance rejection control techniques, which is also present in many traditional approaches that rely on a complex control scheme. Following the successful compensation process, the nonlinear frequency control model can be converted into a quasi-linear model, on which a proportional distributed control algorithm can be developed to restore the frequency and equalize the active power among the DGs.
Source link: https://doi.org/10.3390/en15093184
In an AC microgrid, this paper discusses the most suitable control system for a small switch count AC/AC converter. An example of a mixed grid-feeding-drive system is an AC/AC converter that has been used to interconnect two three-phase renewable energy sources and a three-phase permanent magnet synchronous motor to the grid. Any objective function is limited and the optimization challenge is solved with particle swarm optimization software, while still ensuring that the total harmonic distortion of the current at the points of common coupling is less than 5%.
Source link: https://doi.org/10.3390/electronics7070102
In various operation modes, this research explores the challenge of decentralized control of inverter-based ac microgrids. In addition, the shifted-Hamilton energy function is used as a storage function to ensure incremental passivity and stability of the microgrid device under grid-connected and islanded conditions. In the grid-connected and islanded modes, the simulation shows that the decentralized control dynamics are suited to achieve the desired goal of frequency synchronization, voltage control, and power sharing.
Source link: https://doi.org/10.1186/s41601-019-0120-x
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