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1

Optimal size and location of dispatchable distributed generators in an autonomous microgrid using Honey Badger algorithm

Nguyen Tham X., Lis Robert

Archives of Electrical Engineering

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2023

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Vol. 72, nr 4

871--893

EN

The paper presents a honey badger algorithm (HB) based on a modified backward- forward sweep power flow method to determine the optimal placement of droop-controlled dispatchable distributed generations (DDG) corresponding to their sizes in an autonomous microgrid (AMG). The objectives are to minimise active power loss while considering the reduction of reactive power loss and total bus voltage deviation, and the maximisation of the voltage stability index. The proposed HB algorithm has been tested on a modified IEEE 33-bus AMG under four scenarios of the load profile at 40%, 60%, 80%, and 100% of the rated load. The analysis of the results indicates that Scenario 4, where the HB algorithm is used to optimise droop gains, the positioning of DDGs, and their reference voltage magnitudes within a permissible range, is more effective in mitigating transmission line losses than the other scenarios. Specifically, the active and reactive power losses in Scenario 4 with the HB algorithm are only 0.184% and 0.271% of the total investigated load demands, respectively. Compared to the base scenario (rated load), Scenario 4 using the HB algorithm also reduces active and reactive power losses by 41.86% and 31.54%, respectively. Furthermore, the proposed HB algorithm outperforms the differential evolution algorithm when comparing power losses for scenarios at the total investigated load and the rated load. The results obtained demonstrate that the proposed algorithm is effective in reducing power losses for the problem of optimal placement and size of DDGs in the AMG.

2

Distributed collaborative optimization DC voltage control strategy for VSC–MTDC system with renewable energy integration

Li Jingye, Dong Haiyimg

Archives of Electrical Engineering

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2022

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Vol. 71, nr 2

325--342

EN

Aiming at the problem of DC voltage control deviation and instability caused by a large-scale renewable energy access VSC–MTDC system, this paper combines voltage margin control and droop control. A strategy for controlling collaborative optimization in a sparsely distributed communication network has been proposed. Firstly, the distributed modeling of the system is carried out by combining MAS technology with small signal modeling. Then, a distributed model predictive controller is designed for a single droop control converter station. On this basis, a distributed cooperative optimization control strategy is proposed. According to the DC voltage deviation, the system adopts different control methods to control the receiving converter station. Finally, based on PSCAD/EMTDC and MATLAB co-simulation platforms, a six-terminal flexible HVDC system is built to verify the effectiveness of the control strategy under different conditions such as input power fluctuation, any converter station out of operation and system communication failure.

3

Implementation of Equal Reactive Power Sharing Algorithm in Droop-Controlled Islanded AC Microgrid

Dziułko A, Milczarek A., Malinowski M.

Przegląd Elektrotechniczny

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2015

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R. 91, nr 1

81-87

EN

This paper presents the implementation of the hierarchical control algorithm with droop method and equal reactive power sharing algorithm (ERPS) for an islanded AC microgrid. In the typical applications of microgrid the reactive power flow remains uncontrolled, what may negatively impact the efficiency of the generation unit and cause various problems to power converters. The presented solution will provide an equal reactive power generation by each source, enhancing effectiveness of each generation unit and an overall microgrid reliability and performance.

PL

Artykuł omawia zagadnienia implementacji hierarchicznego systemu sterowania, zawierającego metodę sterowania uchybem amplitudy i częstotliwości napięcia przekształtnika oraz algorytm równomiernego podziału mocy biernej w autonomicznej mikrosieci elektroenergetycznej AC. W klasycznej metodzie sterowania uchybem podział mocy biernej zależy od stosunku mocy czynnych poszczególnych przekształtników. Nie ma możliwości sterowania tym podziałem, co może prowadzić do przeciążenia i wyłączenia przekształtnika bądź cyrkulacji mocy biernej pomiędzy przekształtnikami. Przedstawione rozwiązanie zapewnia równy podział mocy biernej bez względu na zmieniającą się moc czynną, co eliminuje wspomniane problemy.

4

Improvement of microgrid dynamic performance under fault circumstances using ANFIS for fast varying solar radiation and fuzzy logic controller for wind system

Izadbakhsh M., Rezvani A., Gandomkar M.

Archives of Electrical Engineering

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2014

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Vol. 63, nr 4

551--578

EN

The microgrid (MG) technology integrates distributed generations, energy storage elements and loads. In this paper, dynamic performance enhancement of an MG consisting of wind turbine was investigated using permanent magnet synchronous generation (PMSG), photovoltaic (PV), microturbine generation (MTG) systems and flywheel under different circumstances. In order to maximize the output of solar arrays, maximum power point tracking (MPPT) technique was used by an adaptive neuro-fuzzy inference system (ANFIS); also, control of turbine output power in high speed winds was achieved using pitch angle control technic by fuzzy logic. For tracking the maximum point, the proposed ANFIS was trained by the optimum values. The simulation results showed that the ANFIS controller of grid-connected mode could easily meet the load demand with less fluctuation around the maximum power point. Moreover, pitch angle controller, which was based on fuzzy logic with wind speed and active power as the inputs, could have faster responses, thereby leading to flatter power curves, enhancement of the dynamic performance of wind turbine and prevention of both frazzle and mechanical damages to PMSG. The thorough wind power generation system, PV system, MTG, flywheel and power electronic converter interface were proposed by Rusing Mat-lab/Simulink.

5

Control Strategy for Micro-grid system in islanded mode

Qiu L., Xu L., Zheng Z., Li Y.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 3b

57--59

EN

This paper focuses on the control strategies for islanded mode micro-grid system, which consists of wind turbines, photovoltaic panels, batteries and super-capacitors. When micro-grid is connected to the utility grid, DC-bus voltage is regulated by the inverter. And the magnitude and frequency of AC bus are the same with the grid. However when the microgrid works in island mode, DC-bus voltage must be regulated by microsouces and storages. The magnitude and frequency of AC bus are controlled by droop character of parallel inverters. Because of the fluctuation of renewable energy such as wind turbine and photovoltaic, a fast-dynamic storage system (such as super-capacity) is needed. In order to keep supplying power to the local loads in island operation, a long-term storage system (such as lead-acid battery) is needed. All of microsouces and storages are connected to DC bus by different converters. The converters must be controlled well to keep the bus voltage stable and the power flow balance.

PL

W artykule przedstawiono analizę algorytmów sterowania dla mikro-sieci odnawialnych źródeł energii (turbiny wiatrowe, panele fotowoltaiczne, superkondensatory), przy pracy wyspowej. Każdy z elementów sieci podłączony jest poprzez oddzielny przekształtnik i każdy z nich wymaga odpowiedniego sterowania w celu utrzymania stabilnego napięcia szyny DC oraz mocy.

6

Comparing the use of two kinds of droop control under microgrid islanded operation mode

Gao D., Jiang J., Qiao S.

Archives of Electrical Engineering

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2013

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Vol. 62, nr 2

321--331

EN

A microgrid with parallel structure operating under islanded mode is considered in this paper. Under microgrid islanded operation mode, lines bring adverse effect for power distribution between microsources (MSs). Because traditional droop control ignores this effect, MSs adopting this method can not achieve satisfactory power distribution. A kind of droop control including line compensation applied to this microgrid is proposed. It can eliminate this effect to obtain satisfactory power distribution. The relationship of two kinds of droop control with power distribution is analyzed. The reference voltage generated by droop control is applied to control output voltage of MSs. Comparison of two kinds of droop control through MATLAB/Simulink simulation is made to verify the superiority of droop control including line compensation for power distribution. The relationship between PCC voltage and output power of MSs is also presented.