DC-to-DC energy transmission efficiency

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Efficiency evaluation of DC transmission system based on voltage source converter

Efficiency evaluation of DC transmission system based on voltage source converter

The most common way to evaluate the switching losses is to express the switching function as a first or second order polynomial depending on the switching characteristic of the device under consideration. However, with devices used in this paper, the first order approximation is sufficient to estimate the switching energy losses as a function of current with minimum error. Hence, the switching energy losses are expressed as:

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Simulation of Optimized RES Based Power Transfer and Storage System in Cooperative Multi Area Network

Simulation of Optimized RES Based Power Transfer and Storage System in Cooperative Multi Area Network

ABSTRACT: In this paper work, we are using renewable energy sources in order to fulfill load demands in spite of disturbances and loses. In case of sudden congestion, storage of energy will help in fulfilling the required demand. Storage of energy is done frequently so that it will help in case of emergency. Storage of energy is done in flexible manner. In this system, we are using two Renewable energy sources for power generation system. i.e., PV-Array and Wind Mill. Addition of this two Renewable energy sources is fed as input to the system. We are using buck converters to have efficient Battery storage system, as the input voltage level of the PV-Array cell and wind mill is increased to the voltage consumption level of battery, to preserve the battery lifetime this converter will buck the input DC and store it into the battery. One port of the input is given to Converters part and other port of input is given to the Grid. For all our aim is to improve efficiency in renewable power systems and achieve the transmission ranges are improved by using the power station called "Transmission System Operators". Simulation work will be carried out using MATLAB/Simulink in order to achieve the transmission ranges are improved by using the power station, TSO and also improves efficiency.
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Interleaved DC DC Boost Converter with High Voltage Gain and Efficiency for Solar Energy Systems

Interleaved DC DC Boost Converter with High Voltage Gain and Efficiency for Solar Energy Systems

The interleaved boost converter is used here to show that the maximum utilization of available solar energy could be done in a better way than conventional converters available. The converter is realized in a way that the stepped up voltage also has an adequate current rating which is very much essential in faster charging of the battery. With further research and development these converters could very well be used for stepping the voltage for high voltage dc transmission.

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ANALYSIS AND DESIGN OF HIGH BOOST RATIO CONVERTER FOR EFFICIENT ENERGY TRANSFER FROM PV MODULE

ANALYSIS AND DESIGN OF HIGH BOOST RATIO CONVERTER FOR EFFICIENT ENERGY TRANSFER FROM PV MODULE

Attempts were made by scientists for utilizing solar power in different ways. Solar drives, solar water heater, solar concentrators are some examples. Recently because of energy shortage attention was given for generating electric power from solar power. This proposed project presents a non-isolated, high boost ratio hybrid transformer dc-dc converter that has the applications in low voltage renewable energy sources. The proposed converter makes use of a hybrid transformer to transfer the inductive and capacitive energy simultaneously. This helps to achieve a high boost ratio .The proposed system combines pulse width modulation along with resonant mode operation. This helps to minimize the turn off losses of the switch and thereby improving the efficiency of the converter. Since the input to the converter is hybrid linear sinusoidal current waveform, the input current ripple and conduction losses are low. The voltage stresses on the active switch and diodes are maintained at a low level and are independent of the changing input voltage over a wide range as a result of the resonant capacitor transferring energy to the output of the converter.
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A High Efficiency DC-DC Converter with FLC for Solar PV

A High Efficiency DC-DC Converter with FLC for Solar PV

The conventional Boost converters cannot provide such a high dc voltage gain, even for an extreme duty cycle. As a result, the conversion efficiency is degraded and the electromagnetic interference (EMI) problem is severe under this situation [1]. In order to increase the conversion efficiency and voltage gain, many modified boost converter topologies have been investigated in the past decade [4]-[14].

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Dendritic cell mediated HIV 1 transmission to T cells of LAD 1 patients is impaired due to the defect in LFA 1

Dendritic cell mediated HIV 1 transmission to T cells of LAD 1 patients is impaired due to the defect in LFA 1

We have shown before that intercellular adhesion mole- cule-1 (ICAM-1) expression on DC is crucial for HIV-1 transmission to T cells: Monocyte-derived DC subsets that express higher levels of ICAM-1 show higher HIV-1 trans- mission efficiencies to T cells [8], and transmission by both monocyte-derived DC and DC isolated from blood can be inhibited with blocking antibodies against ICAM- 1 [8,10]. During antigen presentation, ICAM-1 expressed by DC binds to T cells via leukocyte function-associated molecule-1 (LFA-1). This interaction plays a key role in the initiation of immune responses by strengthening the adhesion between DC and T cells at the immunological synapse [11-13]. LFA-1 is an integrin composed of the non-covalently bound α L-subunit CD11a and β2-subu- nit CD18 [14]. Lack of proper β2 expression due to a dele- tion or mutation in the CD18 gene leads to Leukocyte Adhesion Deficiency type-1 (LAD-1). Patients with this rare recessive disorder suffer from impaired wound heal- ing without pus formation and recurring necrotic soft tis- sue infections. As CD11/CD18 heterodimers pair intracellularly, LFA-1 is not expressed at the cell surface of leukocytes from LAD-1 patients. The migration of leuko- cytes from the bloodstream into inflamed tissue is conse- quently hampered. In healthy individuals, stimulation of rolling leukocytes along endothelial cell lining induces a conformational change of CD11/CD18 heterodimers from a low to a high ligand-binding state, bringing cells to a halt. As expected, this adhesive process is impaired in LAD-1 patients [15-19]. A unique variant of the LAD-1 disorder has been described (LAD-1/variant syndrome) [20]. Cells of this patient with clinical features of a mild LAD-1 disorder do express LFA-1, but cellular activation does not result in activation of LFA-1, i.e. the 'inside-out signaling' that is necessary for increased ICAM-1 binding is impaired [12,20-22].
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LOADED RESONANT CONVERTOR FOR DC TO DC ENERGY CONVERSION

LOADED RESONANT CONVERTOR FOR DC TO DC ENERGY CONVERSION

This paper presents a new topology for a high efficiency dc/dc resonant power converter that utilizes a resistance compression network to provide simultaneous zero voltage switching and near zero current switching across a wide range of input voltage, output voltage and power levels. The resistance compression network (RCN) maintains desired current waveforms over a wide range of voltage operating conditions. The use of PWM control in conjunction with narrowband frequency control enables high efficiency to be maintained across a wide range of power levels. The converter Implementation provides galvanic isolation and enables large (greater than 1:10) voltage conversion ratios, making the system suitable for large step-up conversion in applications such as distributed photovoltaic converters. Simulation results from a 100 W prototype operating at 500 kHz show that over 95% efficiency is maintained across an input voltage range of25 V to 40 V with an output voltage of 300 V. The output of 300V dc is fed to the separately excited dc motor and speed, torque, armature voltage and armature current is calculated. So we have tested the developed converter for static load and a dynamic load.
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Resonant Converter for the Application of DC-To-DC Energy Conversions

Resonant Converter for the Application of DC-To-DC Energy Conversions

ABSTRACT: Resonant power conversion has many advantages over conventionally adopted pulse-width modulation, which are, low electromagnetic interference, low switching losses, small volume, and light weight of components due to a high switching frequency, high efficiency, and low reverse recovery losses in diodes results to a low di/dt at switching instant. So, this resonant converter is used for direct current (dc)-to-dc energy conversion applications. The proposed resonant converter topology comprises a half-bridge inductor-capacitor-inductor (L-C-L) resonant inverter and a diode bridge rectifier. Then, the output stage of resonant converter is filtered by using low-pass filter. The measured energy conversion efficiency of the resonant converter reaches up to 88.3%. Capacitor-inductor-capacitor(C- L-C) resonant converter is more preferable than the L-C-L resonant converter; because of, it improves the energy conversion efficiency and also reduces the equipment cost. The efficiency of C-L-C resonant converter is up to 93%. Moreover, test results demonstrate a satisfactory performance of the resonant converter. Furthermore, the proposed converter is highly promising for applications of power electronic productions such as switching power supplies, battery chargers, uninterruptible power systems, renewable energy generation systems, and telecom power supplies.
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Photovoltaic Grid-Connected System for Uninterruptible Power Supply in Residential Applications

Photovoltaic Grid-Connected System for Uninterruptible Power Supply in Residential Applications

to the insulated-gate bipolar transistors. The necessity of active clamp or snubber circuit is eliminated by naturally clamping the voltage across the primary device using the secondary modulation technique, which is required in the conventional current-fed topologies. This technique results in the ZCS turn off or natural -commutation of devices. Switching losses are reduced significantly owing to ZCS of primary side switches and ZVS of secondary side switches, which permits higher switching frequency operation with smaller magnetic. At high switching frequency soft switching techniques (ZVS or ZCS) are used to achieve good efficiency and reduced switching stress. In Zero-Voltage Switching (ZVS), the voltage across device is zero just before turn – on. On the other hand in Zero-Current Switching (ZCS), the current through device is zero just before turn-off. For the secondary side of the front-end converter, a voltage doubler or a half-bridge is selected to reduce the number of the switches and transformer turns ratio. The inverter in the secondary side is a bidirectional and therefore permits energy flow from the grid to storage when solar energy is not available.
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Grid integration and power smoothing of an oscillating water column wave energy converter

Grid integration and power smoothing of an oscillating water column wave energy converter

This study uses a supercapacitor bank as the energy storage element, which is connected to the dc-link through a bidirectional dc-dc converter. Supercapacitors have the advantage of long life, high-power density, attractive temperature range, and high charge-discharge efficiency [10]. The SCES is integrated into the OWC electrical power converter system to achieve smooth power delivery to the grid despite varying sea conditions. With the recent advancements of energy storage technologies, supercapacitors have become popular and commercially available for large power applications, such as WEC systems. The supercapacitor specification sheet in [25], confirms that the industrial 83 F or 165 F supercapacitor single modules with 48 Vdc can be connected in series and/or parallel configurations to gain the required voltage and capacity. Moreover, these modules provide up to 1,000,000 charge/discharge cycles. In this particular system, to attain the required voltage of the SCES (1000 V), a minimum 21 of 48 V modules are needed to connect in series, which results in the decrease of the total capacitance and increase of the internal resistance (R sc ) in each pole. Then, these high voltage
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High Step up Switched Capacitor Inductor DC-DC Converter for UPS System with Renewable Energy Source

High Step up Switched Capacitor Inductor DC-DC Converter for UPS System with Renewable Energy Source

Abstract—A new converter using a switched-inductor cell integrated with a switched-capacitor cell within a boost-like structure is proposed. The converter can achieve a very high dc conversion ratio. It can serve as the front-end dc-dc converter for a fuel cell in a UPS system. The inductors and capacitors are switched in a parallel-series configuration. The charging circuit of the inductors from the source is separated from the load. A dc analysis of the new circuit leading to the formula of the dc gain and a breakdown calculation of the losses are given. The proposed Switched Capacitor Inductor (SCI) converter circuit can meet the high efficiency requirement and simple structure. A small resonant inductor is used in these converters to limit the current peak caused by switched capacitor. Therefore, the SCI converters have good performance and high efficiency as well the voltage stress of the converter is reduced. In order to verify the proposed Switched Capacitor Inductor (SCI) dc-dc converter, modeling and simulation was carried out by using MATLAB. 
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A Bridgeless Boost Converter Using Boostand Buck-Boost Strategyfor Low Voltage Energy Harvesting Applications

A Bridgeless Boost Converter Using Boostand Buck-Boost Strategyfor Low Voltage Energy Harvesting Applications

ABSTRACT:The output voltage range of micro and mesoscale energy harvesting equipment is normally equal to some hundred millivolts based on topology of the system. The AC output voltage should first rectified next boosted and then regulated by power electronic converters to meet load voltage requirements. Miniature voltage energy harvesting system necessitates fixed requirement of size and shape for interfacing of power electronic devices. In conventional energy harvesting AC-DC converters it consists of two stages; first stage is diode bridge rectifier for AC-DC conversion and second stage is DC-DC converter which regulates the rectified output but in this conventional converters the major drawback is large voltage drop which makes the low-voltage rectification with lower output and higher losses. The proposed “bridgeless boost rectifier” combines boost and buck-boost converters which has bidirectional conduction capability for AC-DC conversion and it is single stage converter. In this paper input AC 0.4v is rectified and0stepped up0to 3.3v DC. The size of the converter is made compact by using single inductor and capacitor. The results are verified by using MATLAB simulation.
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A Review of Grid Connected Inverters for Photovoltaic System

A Review of Grid Connected Inverters for Photovoltaic System

ABSTRACT: Photovoltaic inverter is an essential element of grid connected Photovoltaic power system consisting of solar panels, inverters, grid connection equipment and power conditioning equipment units. Solar photovoltaic system being weather dependent, maximum power storage can be achieved using MPPT (Maximum Power Point Tracking), plant monitoring, anti-islanding techniques. These techniques enable stable operation at very low irradiation levels. Transformer less inverters based on H Bridge and NPC are highly efficient up to 98%. The use of more number of switches has reduced losses and increased efficiency by 1%. The problem with the photovoltaic inverters is that there are so many topologies and it is difficult to find the standard modules for the implementation.The choice of topology for each inverter should be based on what is the usage of the inverter . As energy demands are rapidly increasing and in view of the reliability and pollution concern the Photovoltaic inverters structures are evolving at a high rate
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Independent analysis methods for Data Centers

Independent analysis methods for Data Centers

 An energy efficiency analysis tailored to data centers provides a structured identification of energy potentials based on the DC-specific Bilfinger Best Practice for energy effic[r]

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Influences of ±800 kV Yunnan Guangdong HVDC System on Security and Stability of China Southern Power Grid

Influences of ±800 kV Yunnan Guangdong HVDC System on Security and Stability of China Southern Power Grid

The interaction mechanism between AC and DC systems in a hybrid AC-DC transmission grid is discussed with PSS/E software. Analysis shows that receiving-end AC faults may cause much more damage on the HVDC system operation than the sending-end AC faults in a multi-infeed HVDC system, and the damage severity depends on the power recov- ering rate of the HVDC systems. For HVDC systems with slow power recovering rate, the receiving-end AC faults may probably be a critical factor to constrain power transfer limits. Larger capacity of HVDC system means not only higher power transfer-limit of the parallel connected AC-DC transmission grid, but also more expensive stabilizing cost. Keywords: HVDC; Security; Stability; AC/DC; Power System; Interaction
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Energy Storage using Flexible stand-alone Photovoltaic PV System on multi loop PI Controller

Energy Storage using Flexible stand-alone Photovoltaic PV System on multi loop PI Controller

A standalone photovoltaic (PV) system with energy storage requires a complex control architecture to take into account the various operating modes. This paper presents a flexible architecture of a PV power conditioning system with energy storage is executed. It consists of boost converter, a single-phase inverter, and bidirectional DC/DC converter connected to the PV side of the boost converter. The boost converter regulates the dc-link bus-voltage. The bidirectional DC/DC converter used for battery charge/discharge control and PV maximum power point tracking. The multi loop PI controller used to control the operation of DC to DC converter. In this system there is no change in controller configuration when the storage disconnects.
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Joydeep Sarkar, Pramod Yade Dept. of Electrical Engineering, Sandip Institute of Engineering & Management, Nashik (MS)

Joydeep Sarkar, Pramod Yade Dept. of Electrical Engineering, Sandip Institute of Engineering & Management, Nashik (MS)

Our electric power system was designed to move central station alternating current (AC) power, via high- voltage transmission lines and lower voltage distribution lines, to households and businesses that used the power in incandescent lights, AC motors, and other AC equipment. Today’s consumer equipment and tomorrow’s distributed renewable generation requires us to rethink this model. Electronic devices (such as computers, florescent lights, variable speed drives, and many other household and business appliances and equipment) need direct current (DC) input. However, all of these DC devices require conversion of the building’s AC power into DC for use, and that conversion typically uses inefficient rectifiers. Moreover, distributed renewable generation (such as rooftop solar) produces DC power but must be converted to AC to tie into the building’s electric system, only later to be re-converted to DC for many end uses. These AC- DC conversions (or DC-AC-DC in the case of rooftop solar) also result in substantial amount of energy losses.
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An Overview of PV Technology by Analyzing Various MPPT Algorithms, Suitable Converters, Stability & Their Cost Estimation.

An Overview of PV Technology by Analyzing Various MPPT Algorithms, Suitable Converters, Stability & Their Cost Estimation.

The global energy crisis and threat of environmental disruption have become a common concern throughout the world. The demand of electricity has increased over the past decades. In case of the frequently used sources of energy such as thermal, oil, gas, etc., the main issue is the availability of limited reservoirs that may be exhausted in the next few years because of their irrational use of humanity. Due to their limitations, renewable energy source is becoming increasingly popular. As such, the photovoltaic (PV), wind farm and biomass are mostly sought after. Among all the sustainable energy sources, solar energy is the most influential energy sources because of its cheapness and profuse availability. The main principle of the solar PV is that light energy can be converted into electrical energy. This energy technology has many advantages, like simplicity, high reliability, low maintenance, minimum time required for installation and operation, doesn’t exist any moving mechanical elements, etc. This type of energy source, as it is traditionally appealing in the countryside, it is economically appropriate for interconnecting to the primary electricity supply. In this case, the PV panels are installed at the top of the houses and, buildings to empower the grid. Therefore, PV module can operate as a small power plant in parallel to the grid of electricity.
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A Novel DC-DC Boost Converter Design for Higher Conversion Efficiency

A Novel DC-DC Boost Converter Design for Higher Conversion Efficiency

A boost converter is the front-end component of a PV system connected between a PV array and a load. It is basically a power converter with DC output voltage greater than its input voltage. It is a class of switching-mode power supply containing at least two semiconductor switches, a diode and a transistor and at least one energy storage element. Filters made of capacitors in combination with inductors are normally added to the output of the converter to reduce the output voltage ripple (Rashid, 2001). An inherent problem in boost converters is that it may cause serious reverse recovery problem which may increase the rating of devices and degrade the conversion. To increase the conversion efficiency, an improvement is made in the boost converter design. Figure 1 shows the MPPT controller with the proposed boost converter design. The converter consists of an inductor in the primary side (L), clamping diodes, D1,D2, capacitor C2 used to form a regenerative circuit to sink the reverse recovery current and an output filter circuit using diode, Do and capacitor, Co.
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Review of dc-dc converters for multi-terminal HVDC transmission networks

Review of dc-dc converters for multi-terminal HVDC transmission networks

Abstract: This paper presents a comprehensive review of high-power dc-dc converters for high-voltage direct current (HVDC) transmission systems, with emphasis on the most promising topologies from established and emerging dc-dc converters. Additionally, it highlights the key challenges of dc-dc converter scalability to HVDC applications, and narrows down the desired features for high-voltage dc-dc converters, considering both device and system perspectives. Attributes and limitations of each dc-dc converter considered in this study are explained in detail and supported by time-domain simulations. It is found that the front-to-front quasi two-level operated modular multilevel converter, transition arm modular converter and controlled transition bridge converter offer the best solutions for high-voltage dc-dc converters that do not compromise galvanic isolation and prevention of dc fault propagation within the dc network. Apart from dc fault response, the MMC dc auto transformer and the transformerless hybrid cascaded two-level converter offer the most efficient solutions for tapping and dc voltage matching of multi-terminal HVDC networks.
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