Optimal operation control of low voltage microgrids in rural areas functioning on the basis of centralized control logic

2018 ◽  
Vol 1 (3) ◽  
pp. 136-140
Author(s):  
Mirosław PAROL
2019 ◽  
Vol 84 ◽  
pp. 02011
Author(s):  
Łukasz Rokicki

The issue of optimal operation control of microgrids is a very important problem. As a result of changing weather conditions and the demand for the power of individual consumers, generation units and energy storage devices must constantly adjust their operation states. The optimization of the microgrid operation states can simultaneously provide the required level of power and energy and, for example, minimization of power losses or costs associated with the operation of this type of system. Among many available optimization methods, author of a paper decided to test the CLONALG algorithm, which is an implementation of artificial immune system. The article will presents the characteristics of selected CLONALG algorithm, and the description of the test microgrid together with the considered optimization criteria and constraints. The presentation and analysis of the obtained results from optimization calculations will be the main part of the paper. At the end of the paper observations and conclusion will be presented.


Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2754
Author(s):  
Mengmeng Xiao ◽  
Shaorong Wang ◽  
Zia Ullah

Three-phase imbalance is a long-term issue existing in low-voltage distribution networks (LVDNs), which consequently has an inverse impact on the safe and optimal operation of LVDNs. Recently, the increasing integration of single-phase distributed generations (DGs) and flexible loads has increased the probability of imbalance occurrence in LVDNs. To overcome the above challenges, this paper proposes a novel methodology based on the concept of "Active Asymmetry Energy-Absorbing (AAEA)" utilizing loads with a back-to-back converter, denoted as “AAEA Unit” in this paper. AAEA Units are deployed and coordinated to actively absorb asymmetry power among three phases for imbalance mitigation in LVDNs based on the high-precision, high-accuracy, and real-time distribution-level phasor measurement unit (D-PMU) data acquisition system and the 5th generation mobile networks (5G) communication channels. Furthermore, the control scheme of the proposed method includes three control units. Specifically, the positive-sequence control unit is designed to maintain the voltage of the DC-capacitor of the back-to-back converter. Likewise, the negative-sequence and zero-sequence control units are expected to mitigate the imbalanced current components. A simple imbalanced LVDN is modeled and tested in Simulink/Matlab (MathWorks, US). The obtained results demonstrate the effectiveness of the proposed methodology.


Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3344
Author(s):  
Enyu Cai ◽  
Yunqiang Yan ◽  
Lei Dong ◽  
Xiaozhong Liao

Zero-voltage ride through (ZVRT) is the extreme case of low-voltage ride through (LVRT), which represents the optimal grid-connection capability of wind turbines (WTs). Enforcing ZVRT will improve the dynamic performance of WTs and therefore significantly enhance the resiliency of renewable-rich grids. A control scheme that includes a pitch system is an essential control aspect of WTs riding through voltage dips; however, the existing control scheme with a pitch system for LVRT cannot distinguish between a ZVRT status and a power-loss condition, and, consequently, does not meet the ZVRT requirements. A system-level control scheme with a pitch system for ZVRT that includes pitch system modeling, control logic, control circuits, and overspeed protection control (OPC) is proposed in this paper for the first time in ZVRT research. Additionally, the field data are shared, a fault analysis of an overspeed accident caused by a voltage dip that describes the operating status at the WT-collapse moment is presented, and some existing WT design flaws are revealed and corrected by the fault analysis. Finally, the pitching performance during a ZVRT, which significantly affects the ZVRT performance of the WT, is obtained from laboratory and field tests. The results validate the effectiveness of the proposed holistic control scheme.


Author(s):  
G. Prathiba ◽  
M. Santhi

This paper presents an analysis of the Reduced Switching Capacitor Digital-to-Analog Converter (RSC-DAC)-based low power Successive Approximation Register Analog to Digital Converter (SAR-ADC). The proposed structure involves the Low voltage Static D-Latch Comparator (LSD-LC) with pre-amplifier operators in two modes (Normal and Hold), the RSC-DAC switching energy, reduced by 93% contrast to the standard Charge Redistribution Switching Capacitor DAC (CRSC-DAC) method, and the Successive Approximation Register (SAR) control logic. The LSD-LC with pre-amplifier consists of a latch circuit and a pre-amplifier. The pre-amplifier is often used to eliminate the DC offset voltage and kickback noise without substantially weakening the Signal-to-Noise Ratio (SNR) to drive the main circuit while the latch is needed for comparison. The linearity parameters such as Integral Nonlinearity, Differential Nonlinearity and effect of parasitic capacitances of the RSC-DAC are analyzed and improved by the new approach named as Adaptive Random Code Generation (ARCG) Technique. The above overall design is implemented in 250-nm CMOS design of the TANNER-EDA tool, consuming 1.74-mW power at 60[Formula: see text]MS/s. The proposed structure has an INL and a DNL, respectively, of +0.18/[Formula: see text] LSB and +0.11/[Formula: see text]0.05 LSB.


2017 ◽  
Vol 32 (6) ◽  
pp. 4340-4350 ◽  
Author(s):  
Philipp Fortenbacher ◽  
Johanna L. Mathieu ◽  
Goran Andersson

Author(s):  
Janaína Goncalves de Oliveira ◽  
Johan Abrahamsson ◽  
Hans Bernhoff

Flywheel Energy Storage Systems (FESS) are a good alternative for power handling and energy storage in hybrid and electric vehicles. The combination of a FESS and a battery has several advantages, such as higher peak power capacity and reduced number of charging/discharging cycles in the battery. Nevertheless, batteries have a significant effect on the performance of the system and the control of the flywheel-battery link should be optimized in order to increase the system efficiency.The FESS investigated in this paper has its novelty in the use of a double wound flywheel machine which divides the system in two different voltage/power levels. High-Voltage/Power (HV) side connects the flywheel machine to the wheel motor and Low-Voltage/Power (LV) side connects the flywheel machine to the battery.The present paper focuses on the converter system and the control logic which regulates battery discharging process and the flywheel rotational speed. Emphasis has been given to the overall power/energy management of the system. Simulations and experimental results show that an ON/OFF battery control allows a highly efficient system, requiring a robust speed control and high energy density for the flywheel machine.


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