scholarly journals A Comprehensive Motivation of Multilayer Control Levels for Microgrids: Synchronization, Voltage and Frequency Restoration Perspective

2020 ◽  
Vol 10 (23) ◽  
pp. 8355
Author(s):  
Ronald Jackson ◽  
Shamsul Aizam Zulkifli ◽  
Mohamed Benbouzid ◽  
Suriana Salimin ◽  
Mubashir Hayat Khan ◽  
...  
Keyword(s):  
Control Method ◽  
Control Strategies ◽  
Renewable Energy Sources ◽  
Hierarchical Control ◽  
Control Level ◽  
Point Of View ◽  
Power Sharing ◽  
Grid Synchronization ◽  
Future Prediction ◽  
And Control

The current paradigm in integrating intermittent renewable energy sources into microgrids presents various technical challenges in terms of reliable operation and control. This paper performs a comprehensive justification of microgrid trends in dominant control strategies. It covers multilayer hierarchical control schemes, which are able to integrate seamlessly with coordinated control strategies. A general overview of the hierarchical control family that includes primary, secondary, tertiary controls is presented. For power sharing accuracy and capability, droop and non-droop-based controllers are comprehensively studied to address further development. The voltage and frequency restoration techniques are discussed thoroughly based on centralized and decentralized method in order to highlights the differences for better comprehend. The comprehensive studies of grid synchronization strategies also overviewed and analyzed under balanced and unbalanced grid conditions. The details studies for each control level are displayed to highlight the benefits and shortcomings of each control method. A future prediction from the authors’ point of view is also provided to acknowledge which control is adequate to be adopted in proportion to their products applications and a possibility technique for self-synchronization is given in this paper.

scholarly journals A Hierarchical Control Methodology for Renewable DC Microgrids Supporting a Variable Communication Network Health

Electronics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 418 ◽  
Author(s):  
Muhammad Shahid ◽  
Muhammad Khan ◽  
Jianming Xu ◽  
Khurram Hashmi ◽  
Salman Habib ◽  
...  
Keyword(s):  
Power Flow ◽  
Renewable Energy Sources ◽  
Hierarchical Control ◽  
Network Connectivity ◽  
Voltage Regulation ◽  
Monitoring And Control ◽  
Dc Microgrids ◽  
Communication Links ◽  
Microgrid Control ◽  
And Control

The monitoring and control of renewable energy sources (RESs) based on DC (Direct Current) microgrids (DC MG) are gaining much consideration at this time. In comparison with the isolated individual control of converters in a microgrid, DC microgrids provide better voltage regulation and harmonized energy generation/consumption. To address the inherent vulnerability of communication links, robust methods have been proposed that improve the resilience of communication-based control. However, the failure of the communication links in microgrid control layers remains a considerable issue that may lead to one or more nodes being disconnected and operating as a communication island. Such types of communication islanding may cause the unpredictable behavior of the system and further destabilization may lead to a cascaded failure. This paper proposes a fast algorithm to detect and evaluate network connectivity based on the information stored at every node in the form of a look-up table. The control structure has been modified under communication islanding, and a communication connectivity observer is used at every node to detect and address power flow issues under communication islanding. The proposed method has been verified through mathematical analysis, simulation, and experimental results.

scholarly journals Secondary Control for Storage Power Converters in Isolated Nanogrids to Allow Peer-to-Peer Power Sharing

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 140 ◽  
Author(s):  
Eva González-Romera ◽  
Enrique Romero-Cadaval ◽  
Carlos Roncero-Clemente ◽  
Mercedes Ruiz-Cortés ◽  
Fermín Barrero-González ◽  
...  
Keyword(s):  
Power Flow ◽  
Control Method ◽  
Low Voltage ◽  
Hierarchical Control ◽  
Power Converter ◽  
Power Sharing ◽  
Primary Control ◽  
Secondary Control ◽  
Control Loops ◽  
Energy Interchange

It is usual in literature that power sharing among grid-forming sources of an isolated microgrid obeys their energy rating, instead of economic agreements between stakeholders, and circulating energy among them is usually avoided. However, these energy interchanges make strong sense and classical power sharing methods must be reformulated in the context of prosumer-based microgrids. This paper proposes a secondary control method for a prosumer-based low-voltage nanogrid that allows for energy interchange between prosumers, where storage systems, together with PV generators, are the controllable grid-forming sources. A power flow technique adapted to islanded microgrids is used for secondary control algorithm and the whole hierarchical control strategy for the prosumer converter is simulated and validated. This hierarchical control consists of three stages: tertiary control plans the energy interchange among prosumers, secondary obtains different voltage and power setpoints for each of the grid-forming sources, and, finally, primary control guarantees stable voltage and frequency values within the nanogrid with droop rules. Inner control loops for the power converter are also defined to track setpoints and assure stable performance. Simulation tests are carried out, which prove the stability of the proposed methods and the accuracy of the setpoint tracking.

scholarly journals Cartography and Epidemiological Study of Leishmaniasis Disease in Sefrou Province (2007–2010), Central North of Morocco

2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Fatima Zahra Talbi ◽  
Fatiha El Khayyat ◽  
Hajar El Omari ◽  
Saâd Maniar ◽  
Mouhcine Fadil ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Cutaneous Leishmaniasis ◽  
Control Strategies ◽  
Age Groups ◽  
Point Of View ◽  
Health Authorities ◽  
Epidemiological Profile ◽  
And Control ◽  
Case Number

Increasing cases of leishmaniasis disease have been reported during recent years in Sefrou Province, Central North of Morocco. This study presents the epidemiological profile of the provincial population, aims at analyzing the epidemiological profile, and in particular, spatiotemporal follow-up of all cases of leishmaniasis. It is a retrospective analysis of leishmaniasis cases recorded between 2007 and 2010. The data were analyzed by SPSS software (version 20). Over a four-year period, from 2007 to 2010, there were 62 cases of leishmaniasis, 93.12% of cases of cutaneous leishmaniasis and 6.87% of visceral leishmaniasis. The case number of leishmaniasis in the Province of Sefrou varies between 0.165% and 0.0018%. For each type of leishmaniasis, the female sex was the most affected compared to the male sex. This difference cannot be considered statistically significant (χ2 = 0.083, p value = 0.77). For cutaneous leishmaniasis, all age groups were affected with a large percentage: patients aged 0–9 years with 63.11% followed by the age group [10–19] with 24.18%. Visceral leishmaniasis mainly has affected the infant population [0–9] with 83.33%. We have not observed any association between the age classes and the leishmaniasis type (χ2 = 6.20, p value = 0.4). From a spatial point of view, the majority of cases of leishmaniasis was reported in El Menzel region (67 cases) followed by Sefrou (64 cases) and Tazouta (38 cases). There is a statistically significant relationship between the type of leishmaniasis and the studied regions (χ2 = 52; p value <0.001). The study of the epidemiological profile of leishmaniasis cases may be useful in enlightening health authorities to develop screening, treatment, and control strategies to reduce the incidence rate of the disease. Other research studies can be conducted to the dynamics of the vectors of sandflies and their ecology.

A Novel Multi-Functional Grid-Connected Inverter of Renewable Energy Resources

2013 ◽  
Vol 448-453 ◽  
pp. 2191-2194
Author(s):  
Lei Zhou ◽  
Hong Da Liu ◽  
Ming Jie Chen ◽  
Nai Jun Shen
Keyword(s):  
Renewable Energy ◽  
Distribution Systems ◽  
Reactive Power ◽  
Control Strategies ◽  
Renewable Energy Sources ◽  
Unit Vector ◽  
Renewable Energy Resources ◽  
Point Of Common Coupling ◽  
Grid Connected Inverter ◽  
And Control

On the basis of analyzing the synthesis application of p-q (instantaneous reactive power) theory and unit vector template, a multi-functional grid-connected inverter (MFGCI) with auxiliary services on power quality enhancement in micro-grid (MG) is presented. The novel control strategy for achieving maximum benefits from these MFGCI when installed in AC MG access to 3-phase 4-wire distribution systems by isolated transformer at the point of common coupling (PCC). This kind of inverter can not only deliver the power generation of renewable energy sources (RESs), but also can perform as active power filter (APF) at their PCC as well as can improve the efficiency of inverter and decrease the hardware investment. Finally, both feasibility and effectiveness of this new topologies and control strategies of MFGCI are verified by PSCAD/EMTDC.

Study on Current Detecting and Control Method for STATCOM across Transformer

2011 ◽  
Vol 130-134 ◽  
pp. 1933-1937
Author(s):  
Cun Ping Wang ◽  
Xiang Gen Yin ◽  
Jian Liu ◽  
Qing Xiong
Keyword(s):  
Reactive Power ◽  
Control Method ◽  
Electronic Device ◽  
Control Strategies ◽  
Power Electronic ◽  
Output Current ◽  
Load Current ◽  
Decoupling Method ◽  
Reactive Current ◽  
And Control

Static var compensator (STATCOM) is a widely used power electronic device for dynamic reactive power compensation, and its current detecting and control method generally adopts d-q decoupling method based on the synchronous rotating coordinate transformation. However, in the traditional method, the load reactive current component is directly used as the command of STATCOM output current, so it is required that the installation position of STATCOM must be consistent with load current detecting point. But in practice, STATCOM installation point and load current detecting point may be located at two different sides of the transformer. For this situation, this paper proposed an improved reactive current detecting and control method based on the principle of power balance, achieving the current detecting and control strategies when the two points are located at different sides of transformer. Finally, the simulation of system with STATCOM accessed from the third winding of transformer verifies the correctness and feasibility of the proposed method.

Control of Quasi-Z Source Inverter with Super Capacitor under Unbalanced Grid Fault Conditions

2013 ◽  
Vol 291-294 ◽  
pp. 2124-2131
Author(s):  
Feng Lin Li ◽  
Shu Ju Hu ◽  
Ling Ling Wang
Keyword(s):  
Reference Frames ◽  
Control Method ◽  
Low Voltage ◽  
Control Strategies ◽  
Renewable Energy Sources ◽  
Super Capacitor ◽  
Loop Control ◽  
Control Scheme ◽  
Unbalanced Grid ◽  
Generation Unit

The quasi-Z-source inverter (qZSI) has some unique advantages and is suitable for renewable energy sources such as solar and wind generation system. In order to make the inverter have the ride-through ability and the current into the grid symmetrical when unbalanced grid faults occur, the topology of qZSI with super capacitor substituting the low voltage capacitor and the unbalance control strategy were proposed. With a super capacitor the system can balance and smooth the power between the generation unit and grid, also the current injected into the grid can be symmetrical through the unbalance control method. The circuit of the new topology and the mathematical model of the three-phase converter under grid voltage unbalance conditions have been analyzed. And then, closed-loop control scheme for the proposed system is used to control the power flow of generation unit, grid and super capacitor in this system, also unbalance control strategies in positive (dq) + and negative (dq) – reference frames have been implemented in the grid-connected qZSI system to make the current into the grid symmetrical during the grid fault. The operating mode during unbalanced grid fault is simulated in MATLAB/Simulink, and the simulation results are presented to verify the theoretical analysis and the control scheme.

scholarly journals State of the Art in Research on Optimum Design, Reliability and Control of Renewable Energy Microgrids

2018 ◽  
Vol 17 (3) ◽  
pp. 23-35 ◽  
Author(s):  
Abubakar Abdulkarim ◽  
Nasir Faruk ◽  
A. O. Oloyode ◽  
Lukman A. Olawoyin ◽  
Segun I. Popoola ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Optimum Design ◽  
Renewable Energy Sources ◽  
Current Status ◽  
Energy Sources ◽  
Future Research ◽  
Research Areas ◽  
Future Prediction ◽  
And Control ◽  
Critical Literature

This paper has presented a comprehensive review in the area of microgrid from the design to implementation. The aim is to evaluate the current status, problems and research efforts toward realising functional microgrids in the power system. The expectations about microgrid are many; therefore the study is divided into three main sections. Recent advancements in the wind energy, solar energy and their future prediction are summarised. States of arts in optimum design of renewable energy microgrid are also investigated. In addition, critical literature review in the reliability analysis of microgrids consisting of renewable energy sources is also reported. Control of microgrids consisting renewable energy sources have been presented. Some examples of existing microgrids across the globe are critically reviewed. The work therefore recommends that energy planners and all stakeholders should consider environmental and regional difference in microgrids planning. Finally, future research areas and directions in these areas are highlighted.

Managing driving disturbances in lateral vehicle dynamics via adaptive integrated chassis control

2020 ◽  
pp. 146441932097737
Author(s):  
Narjes Ahmadian ◽  
Alireza Khosravi ◽  
Pouria Sarhadi
Keyword(s):  
Adaptive Control ◽  
Control Method ◽  
Linear Time ◽  
Hierarchical Control ◽  
Control Level ◽  
Adaptive Controller ◽  
Stability Control ◽  
Control Laws ◽  
Mimo Model ◽  
Yaw Moment

This paper presents a vehicle stability control method based on a multi-input multi-output (MIMO) model reference adaptive control (MRAC) strategy as an advanced driver assistance system (ADAS) to enhance the handling and yaw stability of the vehicle lateral dynamics. The corrective yaw moment and additive steering angle are generated using direct yaw moment control (DYC) and active front steering (AFS) at the upper control level in the hierarchical control algorithm. A nonlinear term is added to the conventional adaptive control laws to handle parametric uncertainties and disturbances. The desired yaw moment generated by the upper-level controller is converted to the brake forces and is distributed to the rear wheels by an optimal procedure at the lower-level. The major contribution of this study is the introduction of a nonlinear integrated adaptive control method based on a constraint optimization algorithm. To verify the effectiveness of the proposed control strategy, the nonlinear integrated adaptive controller, and linear time-varying MRAC are designed and used for comparison. Simulation results are performed for the J-turn and double lane change (DLC) manoeuvres at high speeds and low tyre-road friction coefficients. The desired performance of the proposed controller exhibited significant improvement compared to the conventional MRAC in terms of yaw rate tracking and handling of sideslip limitation.

Study on Fuzzy Multiple Reference Model Adaptive Control Strategies

2014 ◽  
Vol 962-965 ◽  
pp. 2932-2938
Author(s):  
Shu Xing Peng ◽  
Hua Xue ◽  
Dong Dong Li
Keyword(s):  
Adaptive Control ◽  
Control Method ◽  
Reference Model ◽  
Control Strategies ◽  
Dynamic Performance ◽  
Control Precision ◽  
High Dynamic ◽  
Suitable Reference ◽  
And Control ◽  
Multiple Reference

A new fuzzy multiple reference model adaptive control method combined with fuzzy select and conventional adaptive control is presented. To overcome the control difficulties which due to significant and unpredictable system parameter variations, fuzzy logic rules are designed to choose the suitable reference model. The new method is applied to control the speed servo system of dynamic model of BLDCM, and the simulation results show it works well with high dynamic performance and control precision under the condition of great change in reference speed and load torque.

A Study on Multistage Coordination and Control Strategy for JiBei Grid Considering Wind Power Fluctuation

2014 ◽  
Vol 635-637 ◽  
pp. 1194-1198
Author(s):  
Jian Fei Xu ◽  
Yu Jie Xu ◽  
Feng Lu ◽  
Dun Nan Liu ◽  
Peng Yuan Li
Keyword(s):  
Wind Power ◽  
Power Supply ◽  
Control Method ◽  
Hierarchical Control ◽  
Clean Energy ◽  
Control Area ◽  
Power Fluctuation ◽  
Wind Fluctuation ◽  
And Control ◽  
Coordination And Control

The establishment of independent control area for JiBei grid will improve the flexibility of regulation for local units, and absorb more wind power and other clean energy. However, due to the high proportion of wind power capacity and the fluctuation and intermittent of wind power, it presents a challenge to the power supply safety. In this paper, based on the prediction of regulation demand and regulation speed in different time scales, dynamic hierarchical control method is proposed. Several strategies of hierarchical control under the emergency of steady climbing, reverse and fluctuations are established. Hence, it improves the capacity of power supply safety and the proportion of wind absorption. Finally, based on the measurement of characteristics of wind fluctuation, the value of reserve capacity in different control levels is calculated.

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