scholarly journals Generation of Optimal Switching Angle for Nine Level Cascaded H Bridge MLI Using Most Valuable Player Algorithm

2021 ◽  
Vol 12 (6) ◽  
pp. 1919-1927
Author(s):  
Vijaya Anand N, Hema Latha J, G Devadasu, Kumar C
Keyword(s):  
Reactive Power ◽  
Harmonic Distortion ◽  
Voltage Level ◽  
Computing Technique ◽  
Power Exchange ◽  
Point Of Common Coupling ◽  
Terminal Voltage ◽  
Common Coupling ◽  
Micro Grids

Distributed generation (DG) sources often interfaced with grid by a Cascaded H-bridge multilevel inverter with a remote D.C source. The interface inverter has to adapt voltage on the either side of the grid and DG source while it has a control of active and reactive power exchange. The inverter terminal voltage is maintained based on frequency switching technique. However, in applications like micro grids are based on quality of output voltage at the point of common coupling. The present paper discusses an optimal frequency switching methodology that generates optimal fringing angle based on an evolutionary computing technique while maintaining the voltage level at PCC with a reduced harmonic distortion.  Efficacy of the proposed method is illustrated by simulating a 9-level cascaded H bridge in MATLAB environment.

Research of SC for Improving LVRT Capability of FSIG

2012 ◽  
Vol 512-515 ◽  
pp. 758-762
Author(s):  
Guo Qing Li ◽  
Li Meng Wang
Keyword(s):  
Wind Power ◽  
Reactive Power ◽  
Short Circuit ◽  
Wind Farms ◽  
Mathematic Model ◽  
Point Of Common Coupling ◽  
Fast Development ◽  
Terminal Voltage ◽  
Common Coupling ◽  
Short Circuit Fault

The fast development of wind power generation brings new requirements for wind turbine integration to grid. In order to improve the lower voltage ride through(LVRT) capability of fixed speed induction generator(FSIG) in wind power generating systems, the mathematic model of FSIG, supercapacitor(SC) and converter is built in DIgSILENT in this paper. A control strategy for FSIG and SC based on wind farms is proposed to enhance the terminal voltage of point of common coupling (PCC) after the clearance of an external short circuit fault. The simulation results show that the terminal voltage of PCC can be significantly improved when there is extra active and reactive power compensation available from SC.

scholarly journals Innovative Detection of Isolation and Recombination Technique with Micro Grid

2019 ◽  
Vol 9 (1) ◽  
pp. 6829-6836
Keyword(s):  
Distributed Generation ◽  
Reactive Power ◽  
Voltage Sag ◽  
Phase Jump ◽  
Innovative Technique ◽  
Point Of Common Coupling ◽  
In Series ◽  
Common Coupling ◽  
Power Quality Conditioner

An innovative technique of the Unified power quality conditioner for the location, control and integration in the Distributed generation which is based on autonomous and grid connected µg system is proposed and simulated. At Point of Common Coupling, DG converters that has storage andshunt part of APFof UPQC are connected. Before the PCC, the grid and the series part of the UPQC APFare connected in series. Also the DC link is integrated with energy storage. As a secondary mode of control, an innovative technique is introduced in UPQC for the detection of isolation and recombination inµg. Henceforth, it is described as innovative detection of isolation and recombination technique. In this system an effectual method is used for proper functioning of the recombination and isolation detection. Along with the increase in the quality of the power in terms of voltage sag/swell, compensation of the reactive power and harmonics in recombination mode, additionally it compensates voltage interruption over normal UPQC and also DG converter remains connected during the conditions of disturbances in voltage and also phase jump. The performance of the UPQC is simulated and results are analysed.

scholarly journals A Proposed Harmonic Monitoring System for Large Power Users Considering Harmonic Limits

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4507
Author(s):  
Rosalia Sinvula ◽  
Khaled Mohamed Abo-Al-Ez ◽  
Mohamed Tariq Kahn
Keyword(s):  
Monitoring System ◽  
Renewable Energy Sources ◽  
Electronic Devices ◽  
Harmonic Distortion ◽  
Large Power ◽  
High Penetration ◽  
Point Of Common Coupling ◽  
Common Coupling ◽  
Power Utilities ◽  
The Individual

Most power utilities within Southern Africa are faced with the challenges of harmonic distortion due to the high penetration of renewable energy sources (RES) and the use of electronic devices. There is an excessive total harmonic distortion (THD) measured at the point of common coupling (PCC). In this paper, a proposed harmonic monitoring system for large power users (LPUs) is developed. This proposed system considers harmonic limits of the individual and THD of the customers allowed injecting into the network, which should be part of the contractual electricity supply agreement (ESA). Hence, it will enable the monitoring of harmonic distortion to be smooth by determining whether the customer has passed or failed compliance for individual harmonic order and the THD of the voltage. The measurements of harmonic distortion are done using the Unipower power quality (PQ) analyzers that are connected at different points within the industrial network. Measurements of harmonic distortion of an industrial site are compared to the simulation results performed by DIgSILENT software to validate the proposed harmonic monitoring system. Based on the validation results, it is recommended that the ESA between the power utilities and the customers should consist of the harmonic limits.

scholarly journals Induction Motor Drives Fed by an NPC Inverter with Unbalanced DC-Link

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1379 ◽  
Author(s):  
Umberto Abronzini ◽  
Ciro Attaianese ◽  
Matilde D’Arpino ◽  
Mauro Di Monaco ◽  
Giuseppe Tomasso
Keyword(s):  
Output Voltage ◽  
Harmonic Distortion ◽  
Voltage Regulation ◽  
Motor Drives ◽  
Operating Conditions ◽  
Switching Frequency ◽  
Voltage Level ◽  
Voltage Quality ◽  
Vector Modulation

Neutral Point Clamped (NPC) converters with n levels are traditionally controlled in such a way that the DC-link capacitors operate at 1/( n - 1) of the total DC-link voltage level. The voltage level across the DC-link capacitors has to be properly regulated by the capacitor unbalance control to contain the harmonic distortion of the converter output voltages. State-of-the-art modulation techniques address the problem of the DC-link voltage regulation for NPC inverters. However, they highly show reduced performance when unbalanced DC-link voltages are considered. In this paper, a novel Space Vector Modulation (SVM) is proposed for NPC converters with an unbalanced DC-link. At every modulation interval, the technique defines the optimal switching pattern by considering the actual unbalanced DC-link conditions. The proposed modulation allows improving the harmonic content of the NPC converter output voltage with respect to a traditional ML-SVM, when the same operating conditions are considered. As an extension, the proposed modulation technique will guarantee the same output voltage quality of a traditional ML-SVM with unbalanced DC-link, while improving the conversion efficiency thanks to a reduction of switching frequency.

scholarly journals Admittance Reshaping Control Methods to Mitigate the Interactions between Inverters and Grid

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2457 ◽  
Author(s):  
Ling Yang ◽  
Yandong Chen ◽  
An Luo ◽  
Kunshan Huai
Keyword(s):  
Design Method ◽  
Harmonic Distortion ◽  
Response Speed ◽  
Control Methods ◽  
Dynamics Model ◽  
Specific Design ◽  
Three Phase ◽  
Point Of Common Coupling ◽  
Common Coupling ◽  
System Phase

With the increasing impedance coupling between inverters and grid caused by the phase-locked loop (PLL), traditional three-phase inverters suffer from the harmonic distortion or instability problems under weak grid conditions. Therefore, the admittance reshaping control methods are proposed to mitigate the interactions between inverters and grid. Firstly, a dynamics model of traditional inverter output admittance including main circuit and PLL is developed in the direct-quadrature (dq) frame. And the qq channel impedance of the inverter presents as a negative incremental resistance with the PLL effect. Secondly, two admittance reshaping control methods are proposed to improve the system damping. The first reshaping technique uses the feedforward point of common coupling (PCC) voltage to modify the inverter output admittance. The second reshaping technique adopts the active damping controller to reconstruct the PLL equivalent admittance. The proposed control methods not only increase the system phase margin, but also ensure the system dynamic response speed. And the total harmonic distortion of steady-state grid-connected current is reduced to less than 2%. Furthermore, a specific design method of control parameters is depicted. Finally, experimental results are provided to prove the validity of the proposed control methods.

Evaluating Constant DC-Link Operation of Wave Energy Converter

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Rickard Ekström ◽  
Venugopalan Kurupath ◽  
Cecilia Boström ◽  
Rafael Waters ◽  
Mats Leijon
Keyword(s):  
Wave Energy ◽  
Power Output ◽  
Wave Energy Converter ◽  
Damping Factor ◽  
Energy Converter ◽  
Sea State ◽  
Voltage Level ◽  
Electromagnetic Damping ◽  
Point Of Common Coupling ◽  
Common Coupling

A wave energy converter (WEC) based on a linear generator and a point-absorbing buoy has been developed at Uppsala University. Interconnecting an array of WECs in parallel requires a point of common coupling, such as a common dc-bus. The dc voltage level seen by the generator is directly linked to the electromagnetic damping of the generator. A lower dc-level results in a higher damping factor and is important for increased absorption of the wave power. The drawback is increased losses in generator windings and cable resistance. There will be an optimal dc-level for maximum power output. This is a function of not only generator and buoy characteristics, but the current sea state. Experimental results of the full-scale system have been carried out, and used as validation of a simulation model of the system. The model is then used to evaluate how the dc-level seen by the generator influence the power output. The results indicate that higher dc-levels should be used at higher sea states, and power output may vary by up to a factor five depending on which dc-level is chosen.

A New Compensation Control Strategy for Grid-connected Wind Turbine and Fuel Cell Inverters in a Microgrid

2017 ◽  
Vol 8 (1) ◽  
pp. 272 ◽  
Author(s):  
A. Naderipour ◽  
A. A. Mohd Zin ◽  
M. H. Habibuddin ◽  
M. Moradi ◽  
M. Miveh ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Wind Turbine ◽  
Distributed Generation ◽  
Control Method ◽  
Harmonic Distortion ◽  
Synchronous Reference Frame ◽  
Wide Range ◽  
Point Of Common Coupling ◽  
Frame Method ◽  
Common Coupling

The use of a new control method for grid-connected inverters for reducing the output current harmonic distortion in a wide range of grid-connected distributed generation (DG) applications, including wind turbine (WT) and fuel cell (FC) inverters is proposed in this paper. The control method designed to eliminate main harmonics in a microgrid (MG) and between MG and point of common coupling (PCC) and responsible for the correction of the system unbalance. Another advantage of the proposed control method is that it can be easily adopted into the DG control system without the installation of extra hardware. The proposed control method is comprised of the synchronous reference frame method (SRF). Results from the proposed control method are provided to show the feasibility of the proposed approach.

scholarly journals Distortion Load Identification Based on the Application of Compensating Devices

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1430 ◽  
Author(s):  
Yaroslav Shklyarskiy ◽  
Aleksandr Skamyin ◽  
Iaroslav Vladimirov ◽  
Farit Gazizov
Keyword(s):  
Reactive Power ◽  
Electric Load ◽  
Electrical Grid ◽  
Voltage Distortion ◽  
New Methods ◽  
Point Of Common Coupling ◽  
Limited Application ◽  
Common Coupling ◽  
Compensating Devices ◽  
Grid Operation

The article provides an analysis of the existing methods of identifying the consumer’s contribution to voltage distortion at a point of common coupling. The considered methods do not allow correctly and fairly determining the source of harmonic distortions, or they have limited application and difficulties in implementation. The paper proposes new methods for determining the source of high harmonics. The developed methods and techniques are based on the analysis of the grid operation modes with two connected consumers using compensating devices, such as reactive power compensation devices and passive harmonic filters. It is shown that the most promising method is the application of harmonic filters, which allows determining the share of the consumer’s contribution to the voltage distortion. The present research is carried out using a computer simulation of the existing electrical grid, to which consumers with nonlinear electric load are connected. These methods can be implemented to assess the power quality and the shareholding of different consumers connected at the point of common coupling. Furthermore, such methods appear to be feasible, as almost every enterprise currently has such facilities in operation.

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