scholarly journals A Novel Hybrid Converter Proposed for Multi-MW Wind Generator for Offshore Applications

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4167 ◽  
Author(s):  
Muhammad Luqman ◽  
Gang Yao ◽  
Lidan Zhou ◽  
Tao Zhang ◽  
Anil Lamichhane
Keyword(s):  
Power Distribution ◽  
Semiconductor Devices ◽  
Power Converter ◽  
Offshore Wind ◽  
Total Power ◽  
Power Devices ◽  
Electric Grid ◽  
Current Stress ◽  
Wind Generator ◽  
Three Phase

Modern multi-MW wind generators have used multi-level converter structures as well as parallel configuration of a back to back three-level neutral point clamped (3L-NPC) converters to reduce the voltage and current stress on the semiconductor devices. These configurations of converters for offshore wind energy conversion applications results in high cost, low power density, and complex control circuitry. Moreover, a large number of power devices being used by former topologies results in an expensive and inefficient system. In this paper, a novel bi-directional three-phase hybrid converter that is based on a parallel combination of 3L-NPC and ‘n’ number of Vienna rectifiers have been proposed for multi-MW offshore wind generator applications. In this novel configuration, total power equally distributes by sharing of total reference current in each parallel-connected generator side power converter, which ensures the lower current stress on the semiconductor devices. Newly proposed topology has less number of power devices compared to the conventional configuration of parallel 3L-NPC converters, which results in cost-effective, compact in size, simple control circuitry, and good performance of the system. Three-phase electric grid is considered as a generator source for implementation of a proposed converter. The control scheme for a directly connected three-phase source with a novel configuration of a hybrid converter has been applied to ratify the equal power distribution in each parallel-connected module with good power factor and low current distortion. A parallel combination of a 3L-NPC and 3L-Vienna rectifier with a three-phase electric grid source has been simulated while using MATLAB and then implemented it on hardware. The simulation and experimental results ratify the performance and effectiveness of the proposed system.

scholarly journals A Low-Power Setup Proposal for Power Transformer Loading Tests

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4133
Author(s):  
Thiago Galvão ◽  
Domingos Simonetti
Keyword(s):  
Low Power ◽  
Power Distribution ◽  
Power Level ◽  
Fractional Power ◽  
Voltage Regulation ◽  
Power Converter ◽  
Operating Conditions ◽  
Voltage Source ◽  
Total Power ◽  
Distribution Grid

A setup for testing transformers under load through low power converter is presented in this paper. This setup is used for testing power transformers as it allows to verify their performance under operating conditions regarding aspects such as heating, voltage regulation, and mounting robustness. The main goal of the study is centered on replacing a full power Back-to-Back converter (1 pu) by a fractional power one (less than 0.1 pu). The converter, a Voltage Source Inverter (VSI), is a series connected between two equally sized transformers and controls the current flowing in the system. Load profile configurations set according to power factor, current harmonics, or even power level can be imposed to evaluate the performance of the Transformer Under Test (TUT) and the entire system. Theoretical analysis, and simulation results employing Matlab/Simulink platform, considering a typical transformer of a 75 kVA power distribution grid with 13.8 kV/220 V voltage are presented to corroborate the proposal. The required VSI power achieved in the simulations is a fraction of the total power of transformer under test, and the grid power consumed is also of small order justified by losses.

scholarly journals Investigating Variable Speed Wind Turbine Transient Performance Considering Different Inverter Schemes and SDBR

2021 ◽  
Vol 8 ◽  
Author(s):  
Kenneth E. Okedu ◽  
Hind F. A. Barghash
Keyword(s):  
Wind Turbine ◽  
Computer Aided Design ◽  
Power Converter ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Transient Performance ◽  
Hybrid Scheme ◽  
Wind Generator ◽  
Ground Fault ◽  
Three Phase

In wind energy applications, voltage source converters are employed to achieve energy conservation. Recently, multilevel converters have been showing promising advantages compared to the traditional 2-level converter scheme, due to the fact that they can overcome certain limitations during transient conditions. This paper investigates the transient performance of variable DFIG-based speed wind turbines taking into account different scheme configurations of the power converter system. The schemes investigated are a 2-level six step IGBT inverter, a parallel interleaved 2-level six step IGBT inverter, and a 3-level IGBT inverter. All schemes were compared during severe three-phase to ground fault at the terminal of the DFIG wind turbine using the conventional Phase Lock Loop (PLL) and a DC-chopper protection. A coordinated approach of improving the performance of all the converter schemes with series dynamic braking resistor (SDBR) was analyzed. Investigation of the best location for the SDBR in the DFIG architecture considering the best switching signal was also carried out. Furthermore, a new control strategy of PLL for the DFIG system was proposed in conjunction with the SDBR scheme for the converter systems. Simulations were carried out in Power System Computer Aided Design and Electromagnetic Transient Including DC (PSCAD/EMTDC). The results show that the proposed PLL and SDBR hybrid scheme in the various inverter topologies considered in the study can enhance the performance of the wind generator variables during severe three-phase to ground fault. This is because the proposed hybrid scheme could help to boost the capability of the current and recovery of the wind generator after post-fault scenarios. Also, the voltage source converter leg switched output voltage would be enhanced to maximum change in common mode voltage by the inverter schemes’ modulation of the space vector using the proposed strategy.

Improving the efficiency of oilfield electric power distribution

2019 ◽  
pp. 79-87
Author(s):  
Yu. F. Yu. F. Romaniuk ◽  
О. V. Solomchak ◽  
М. V. Hlozhyk
Keyword(s):  
Power Distribution ◽  
Reactive Power ◽  
Power Transmission ◽  
Transmission Efficiency ◽  
Active Power ◽  
Oil Field ◽  
Total Power ◽  
Simultaneous Increase ◽  
Active Load ◽  
Step Down

The issues of increasing the efficiency of electricity transmission to consumers with different nature of their load are considered. The dependence of the efficiency of the electric network of the oil field, consisting of a power line and a step-down transformer, on the total load power at various ratios between the active and reactive components of the power is analyzed, and the conditions under which the maximum transmission efficiency can be ensured are determined. It is shown by examples that the power transmission efficiency depends not only on the active load, but also largely on its reactive load. In the presence of a constant reactive load and an increase in active load, the total power increases and the power transmission efficiency decreases. In the low-load mode, the schedule for changing the power transmission efficiency approaches a parabolic form, since the influence of the active load on the amount of active power loss decreases, and their value will mainly depend on reactive load, which remains unchanged. The efficiency reaches its maximum value provided that the active and reactive components of the power are equal. In the case of a different ratio between them, the efficiency decreases. With a simultaneous increase in active and reactive loads and a constant value of the power factor, the power transmission efficiency is significantly reduced due to an increase in losses. With a constant active load and an increase in reactive load, efficiency of power transmission decreases, since with an increase in reactive load, losses of active power increase, while the active power remains unchanged. The second condition, under which the line efficiency will be maximum, is full compensation of reactive power.  Therefore, in order to increase the efficiency of power transmission, it is necessary to compensate for the reactive load, which can reduce the loss of electricity and the cost of its payment and improve the quality of electricity. Other methods are also proposed to increase the efficiency of power transmission by regulating the voltage level in the power center, reducing the equivalent resistance of the line wires, optimizing the loading of the transformers of the step-down substations and ensuring the economic modes of their operation.

Resonant BLDC Motor Drive System for Medical Applications

2019 ◽  
Vol 14 ◽  
Author(s):  
C. Vidhya ◽  
V. Ravikumar ◽  
S. Muralidha
Keyword(s):  
High Frequency ◽  
Pulse Width Modulation ◽  
Power Converter ◽  
Low Power Consumption ◽  
Motor Drive ◽  
Medical Applications ◽  
Bldc Motor ◽  
Three Phase ◽  
High Frequency Ac ◽  
Motor Drive System

: The objective of this paper is to implement an ac link universal power converter controlled BLDC motor for medical applications. The ac link universal power converter is a soft switched high frequency ac link converter, created using the parallel combination of an inductor and a capacitor. The parallel ac link converter handle the ac voltages and currents with low reactive ratings at the link and offers improved power factor, low power consumption, more efficiency and less weight on comparison with the traditional dc link converter. Because of the high throughput, BLDC motors are preferred widely medical applications. A modulation technique called Space Vector Pulse Width Modulation (SVPWM) is used to generate the three phase power for the BLDC motors from the input DC supply. To validate the proposed system, simulations are performed in MATLAB – Simulink and an experimental prototype is constructed to supplement the simulation results.

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