AC-DC voltage transfer

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The protection and interconnection of HVDC grids

The protection and interconnection of HVDC grids

For bulk-power and long-distance transmission, most of the existing HVDC systems are point-to-point LCC-HVDCs. By interconnecting existing LCC links can achieve more economical benefits and higher flexibility of power transfer. However, due to different voltage levels and control modes of these links, it is impossible to interconnect them together directly through dc cables. Interconnecting LCC links via a DC transformer at a geographic crossing point or close proximity between the LCC links is proposed. Such connection is to achieve the benefits of dc grid operation without incurring a vast amount of costs by constructing new HVDC transmission lines but making full use of existing LCC lines. As one type of the interconnected device between HVDC systems, the DC/AC/DC converter is able to achieve high-voltage connection and bulk-power transportation, which makes this device fit the interconnection of LCC-HVDCs. The DC/AC/DC converter based on half-bridge sub-modules is designed for power regulation between two LCC links under different voltage levels.
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An Indirect Matrix Converter with Unity Voltage Transfer Ratio for Ac To Ac Conversion

An Indirect Matrix Converter with Unity Voltage Transfer Ratio for Ac To Ac Conversion

adjustable speed drive systems or other types of loads. Several methods to reduce common-mode voltage have been proposed [6]-[9]. However, these methods were established for matrix converters with an AC output. The first relevant modulation method for the IMC is the standard SVM method, which is presented in [11]- [13]. However, the CMV reduction is not considered in these researches. The standard SVM method provides the peak CMV equal to the input phase voltage magnitude. In [10], [15] two modulation methods are proposed to reduce CMV for IMC. The first method uses the highest and medium line-to-line input voltage to generate the dc- link voltage and four active vectors are used in the inverter stage to generate the reference output voltage vector. The maximum voltage transfer ratio is unaffected and remains at 0.86. However, this method has some drawbacks such as the high total harmonic distortion in line-to-line output voltage and the high switching losses in the inverter stage. The second one uses the smallest and medium line-to-line input voltage to generate the dc- link voltage and also considers the zero vectors in the inverter stage. The advantage of this method is the high performance at output voltage. However, it allows a maximum voltage transfer ratio of 0.5.
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AC voltage control of DC/DC converters based on modular multilevel converters in multi-terminal high-voltage direct current transmission systems

AC voltage control of DC/DC converters based on modular multilevel converters in multi-terminal high-voltage direct current transmission systems

The AC current, like the DC current, flows through MMC arm semiconductors. With increased AC voltages, the AC currents are correspondingly reduced to transfer rated power, yielding lower losses, especially conduction losses. Thus, MMCs are sensitive to AC voltage, which is preferably higher to reduce conduction losses and SM capacitances. However, the AC voltages need to be within the MMC output voltage capabilities to avoid over-modulation and ensure converter dynamics. When an MMC is a terminal station, the voltage of the AC grid connected to the MMC is allowed to fluctuate in the range of ± 10% and thus the modulation index of the MMC terminal station is conventionally set between 0.75 and 0.85 [11,12]. Moreover, the AC voltage of the DC/DC converter is controllable and regulated by one MMC of the DC/DC converter. As a result, by properly setting the AC voltage of the DC/DC converter, the conduction losses can be significantly reduced while avoiding over-modulation [7].
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Z Source Inverter for Three-Phase Induction Motor Suresh Veer 1, Rajat Ganjre2 , Aishwary Kumbhalkar 3, Sakshi Harne4 , C. J. Sharma 5

Z Source Inverter for Three-Phase Induction Motor Suresh Veer 1, Rajat Ganjre2 , Aishwary Kumbhalkar 3, Sakshi Harne4 , C. J. Sharma 5

This paper present the impedance source inverter for adjustable speed drive (ASD). Utilization of ZSI in industrial applications greatly increases the reliability by allowing only lower inrush current; lower harmonic injection and high immunity to EMI noises. Z Source Inverter can overcome this limitation, with the use of impedance source network. The impedance network connected between rectifier and inverter circuit, act as storage during input voltage, higher than required voltage and provide string voltage during input voltage is less than required voltage. By controlling shoot through duty cycle impedance source can be produce required ac voltage even greater than line voltage. As a result this impedance source system, provides, capability during voltage sag and swell, reduce harmonic, improve power factor and reliability, and extent the output voltage, analysis simulation and experimental result can be analyzed.
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Ringing and Voltage Overshoot Analysis of a Proposed DC/AC Converter

Ringing and Voltage Overshoot Analysis of a Proposed DC/AC Converter

This research presents a study of the ringing and voltage overshoot analysis of a proposed DC/AC converter. This overvoltage is generated due to the resonance between three passive components: transformer leakage inductances, switch capacitances, and wiring resistances. By applying simple RLC circuit equations, it proves possible to determine the analytic equations and reproduce the voltage across the switches to predict the overvoltage and resonance frequency. The circuit is built and tested experimentally to validate the theoretical concept.

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Adaptive Voltage Control of a 3-Phase Inverter for a Standalone Distributed Generation

Adaptive Voltage Control of a 3-Phase Inverter for a Standalone Distributed Generation

Abstract:— Multilevel inverters have received more attentions their considerable advantages such as high power quality, lower harmonic components, better electro- magnetic consistence, lower dv/dt and lower switching losses. Lot of research was going on multi level inverter topologies and many researchers are proposed so many multi level inverter topologies. This paper proposes a robust adaptive voltage control of three-phase voltage source inverter for a distributed generation system in a standalone operation. The proposed adaptive voltage control technique combines an adaption control term and a state feedback control term. The proposed algorithm is easy to implement, but it is very robust to system uncertainties and sudden load disturbances. With the proposed system, we can achieve fast transient response, zero steady-state error, and low THD.Mathematical modeling and simulation studies using Simpower systems Block set of MATLAB are proposed. Switching scheme for the proposed converter circuit is designed with the help of sinusoidal pulse width modulation scheme. Total Harmonic distortion in the output voltage is evaluated using FFT tool of MATLAB SIMULINK.
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Three-Phase Multistage System (DC-AC-DC-AC) for Connecting Solar Cells to the Grid

Three-Phase Multistage System (DC-AC-DC-AC) for Connecting Solar Cells to the Grid

Inverter systems that feed electrical power from photovoltaic (PV) system into the grid must convert the direct current of the PV array into the alternating current of the grid. In many applications, it is important for a converter to be lightweight, highly reliable, input/output isolated, flexible and operable in a boost mode. These features can be achieved by using a High-Frequency inverter which involves an isolated DC-DC stage and DC-AC section, which provides AC output. This paper proposes a new three phase topology, based on multi stage converter and PV system in order to use in medium and high power applications. The Perturb and Observe (P&O) method is used for maximum power point tracking (MPPT) control of PV array. The switching control signals for three-phase inverter are provided by hysteresis control method. Also, the comparison between the proposed topology and traditional structures has been conducted and finally the simulation researches are performed in a closed-loop control system by MATLAB/Simulink software to verify the operation of the proposed structure. The results represent better performance of the introduced system over traditional topologies.
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(free energy) 100kv from bike generator pdf

(free energy) 100kv from bike generator pdf

Voltage AC or DC currant, Thru the use of a High Voltage Transformer or a Voltage doubler in this case a voltage multiplier. It's very simple but powerful. The capacitor creates the new amperage and high voltage thru the use of diodes This a fun science project and can be used in many experiments that involves high voltage.

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Series Voltage Compensator Modeling and Design for Reduction of Grid Tie Solar Inverter Dc Link Capacitance

Series Voltage Compensator Modeling and Design for Reduction of Grid Tie Solar Inverter Dc Link Capacitance

[4] Film Capacitors for Industrial Applications, EPCOS Application Note, EPCOS AG, Munich, Germany, 2007. [5] S. Harb and R. S. Balog, “Reliability of candidate photovoltaic module integrated- inverter (PV-MII) topologies—a usage model approach,” IEEE Trans. Power Electron., vol. 28, no. 6, pp. 3019–3026, Jun. 2013. [6] P. Pelletier, J. M. Guichon, J. L. Schanen, and D. Frey, “Optimization of a DC capacitor tank,” IEEE Trans. Ind. Appl., vol. 45, no. 2, pp. 880–886, Mar./Apr. 2009. [7] D. Lamar, J. Sebastian, M. Arias, and A. Fernandez, “On the limit of the output capacitor reduction in power- factor correctors by distorting the line input current,” IEEE Trans. Power Electron., vol. 27, no. 3, pp. 1168– 1176, Mar. 2012.
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AN UNBALANCED LOAD CONTROL FOR THREE PHASE POWER CONVERTER IN DISTRIBUTION SYSTEM

AN UNBALANCED LOAD CONTROL FOR THREE PHASE POWER CONVERTER IN DISTRIBUTION SYSTEM

The power flow is observed by controlling the amplitude and angle of displacement between the voltage generated by the DG and the grid voltage, i.e., the command variable is the same before and after the islanding methods obtained. The voltage control provide the capability to supply different types of loads to the DG system, such as linear, nonlinear, machine, constant, or unbalance, As like, if the DG working in the islanding performance. These kinds of controls are useful for D Separating in parallel as each of the DGs are joined to the grid through a distribution transformer (DT).As like this, the other process introduced in are more effective. This paper analyses the results caused by 50 to 5000-kVADG sources placed into the distribution network, whether the local load is linear or nonlinear, or if the grid is working under abnormal states. Section II considers the process used to drive both converters. Section III considers the technique to control the power flow through the grid. Sections IV and V display the simulations and experimental setup to support the previous analysis, while the main points extend in this paper appearing the conclusion.
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Grid-Tied Solar System

Grid-Tied Solar System

To meet the non-maleficence framework, a cost-benefit analysis may be conducted because the design involves dangerous elements like high current and voltage above 120V. However, it becomes crucial when doing the cost-benefit analysis involving human lives, because the Ford Pinto tragedies should not get repeated [16]. The Ford Motor Company chose not to upgrade the Pinto’s fuel system design, which caused 180 deaths. All engineers should identify any immoral practices related to safety issues and enhance their ethical sensibilities. Reinforcing the IEEE Code of Ethics should provide a guideline and safety boundaries. This design contains safety features like overcurrent protection and overvoltage protection via circuit breakers and protection relays.
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Modified Multi level Dual Input Dual Buck Inverter

Modified Multi level Dual Input Dual Buck Inverter

In recent years, multilevel inverters are attracting lot of attentions due to the increasing higher power quality requirements. It possesses the several features such as reduced harmonic distortion, near sinusoidal output voltage waveform and reduces dv/dt stress. As a result, multilevel inverters are used in industrial applications to meet the requirements. Inverter performs DC to AC conversion for distributed electrical energy systems and electrical vehicles. Multilevel inverter produce a stepped output voltage with are fined harmonic profile compared to two level inverters.
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Relays & Sockets. RH Series Compact Power Relays. Part Number Selection

Relays & Sockets. RH Series Compact Power Relays. Part Number Selection

Between live and dead parts: 2,000V AC, 1 minute Between contact and coil: 2,000V AC, 1 minute Between contacts of different poles: 2,000V AC, 1 minute Between contacts of the same pole: 1,000V AC, 1 minute Operating Frequency Electrical: Mechanical: 1,800 operations/hour maximum 18,000 operations/hour maximum Vibration Resistance Damage limits: Operating extremes: 10 to 55Hz, amplitude 0.5 mm 10 to 55Hz, amplitude 0.5 mm

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Induction Motor Fed By Γ Z  Source Inverter

Induction Motor Fed By Γ Z Source Inverter

Abstract: The main focus is on the losses that occur in an Induction motor and to select a suitable Inverter that feeds the Induction motor. Various analysis are performed on the different types of Inverters and on completion of those analysis, the Gamma Source Inverter has better performance characteristics is chosen to fed the Induction motor. This project also deals with the possibility of energy savings in Induction motor. The modeling of Gamma source inverter has been presented using MATLAB/SIMULINK. The normal Impedance-source Inverters are Inverters with voltage-buck-boost capability that cannot be achieved by the traditional Inverters. Their boost capability is introduced by shorting their phase legs without causing damages. Impedance-source inverters are therefore less prone to false triggering caused by electromagnetic interference. Present Impedance-source inverters are, however, burdened by their low modulation ratio at high input-to-output gain. Such low modulation usually leads to high-voltage stresses across the components and poor spectral performance at the inverter output. To avoid these problems, Inverters with coupled transformers have been introduced, but they usually lead to high turns ratio, and hence many winding turns, at high gain. An alternative would then be the asymmetrical Γ- source Inverters proposed in this paper, whose Gain is raised by lowering their turns ratio toward unity. The input current drawn by the proposed inverters is smoother and, hence, more adaptable by the source. Theories and experimental results have been presented in this paper for validating the concepts proposed.
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Smart Charging of EV by Magnetic Resonance Coupling With Dual Substantiation

Smart Charging of EV by Magnetic Resonance Coupling With Dual Substantiation

The 12V, 60HZ ac supply is given to the filter from HF converter. It reduces the harmonics and ripples. Here the 25 micro farad capacitor is act as a filter. The output from filter is given to transmitting coil. The power is transferred to receiving coil from transmitting coil. In the charging unit the 12V ac supply is converted to 12V dc supply and charge the battery.

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Batteries charging systems for electric and plug-in hybrid electric vehicles

Batteries charging systems for electric and plug-in hybrid electric vehicles

Also, in this chapter it was presented a laboratory prototype of a bidirectional EV batteries charging system, and shown some experimental results, which allows mitigating the power quality degradation of the power grid. During the batteries charging process, the voltage and the current in the batteries are controlled in order to maximize their lifespan, and at the same time consuming from the power grid sinusoidal current with unitary power factor. This batteries charging system also permits to deliver back to the power grid part of the energy stored in the batteries, which can be, in the near future, an interesting solution during short periods of time, when occur peaks of energy demand in the power grid.
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Influence of Impurity Concentration on Insulation Strength of Insulating Oil under Different Voltage Types

Influence of Impurity Concentration on Insulation Strength of Insulating Oil under Different Voltage Types

Converter transformer is the key equipment of high voltage direct current transmission system. The insulating performance of transformer oil is quite sensitive to nonmetallic and metallic particles originating from the process of installation and operation of converter transformers. As to the high electrical field, the particle easily leads to partial discharge and breakdown in transformer oil. This paper construct the AC/DC composite experiment platform. And the breakdown voltages of transformer oil with different carbon particle diameter or concentration level are investigated at AC, DC and combined AC and DC voltage, respectively. The influence of carbon particle diameter, concentration and voltage type on the breakdown strength of insulating oil are obtained. The experimental results showed that the breakdown voltage of insulating oil with carbon particle approximately comply with Waybill distribution. The voltage type has a significant influence on the breakdown voltage of insulating oil. The breakdown voltages are decrease under AC voltage, combined AC and DC voltage and DC voltage. With the diameter and concentration of carbon particle increase, the breakdown voltage of insulating oil will decrease. The analysis result shows that the carbon particle will form carbon particles bridges, and which will affect the breakdown voltage of insulating oil.
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Application of energy storage devices for uninterruptable power supply for wind energy conversion system

Application of energy storage devices for uninterruptable power supply for wind energy conversion system

Fuel cell (FC) can provide clean power to users with zero emissions. Due to its high efficiency, stable operation, and sustainable/renewable fuel supply, FC has been considered and increasingly accepted as a competent alternative source for the future [4], [5]. However, several drawbacks impose hurdles against wide application of FC-based power systems. In past literature, a variety of power converter topologies and control methods was proposed to interface FC to different loads [9], [10], [11]. The authors in [7]–[12] use a capacitor as energy buffer for FC power conditioning where high-frequency switching and active ripple cancellation techniques are used; the challenge in FC-inverter interfacing was identified, and several control methods were proposed. References [13]–[23] incorporate energy storages, such as battery and ultra-capacitor, to form hybrid power system in various system structures; multiple input converter topologies are adopted and energy flow is controlled based on operation scenarios. In the presence of three inputs/storages, [17] proposed state machine-based power management algorithm to achieve constant power drawn from FC and healthy operation of high-voltage battery pack; [14] offers method of system design and local controller design based on power source dynamics. Although the control system was implemented in a single DSP controller, the control system design in [14] is focused on individual local controller design, and system modes of operation are not clearly defined, which has room for great improvement in all scenario and sustainable operation.
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Sustainable Development Microgrid Advanced Control and Protection System

Sustainable Development Microgrid Advanced Control and Protection System

The two-level Voltage Source Converter (VSC) with Buck converter is selected as the AC/DC interface to use to interconnect ac and dc power systems since it has a wide range output DC link voltage [1], can be designed to have a high transient performance during faults and disturbances, and it is suitable to be used with energy storage. Galvanic isolation can be achieved by adding a transformer with unity ratio before the VSC. The control system of the AC/DC interface consists of two independent parts: one for the VSC and one for the Buck converter [2]. Control of Three-Phase Two-Level Voltage Source Converter by using pulse width modulation (PWM) the output voltage of the VSC can be controlled, and hence the voltages across the grid filter. This means that the current through the filter can be controlled, and in turn the power flows between the grid and the VSC [3]. The power flow can be bi-directional, and active and reactive power can be individually controlled [4]. The VSC current control system adopted here uses a vector controller implemented in the synchronous DQ- coordinate system, where the positive sequence ac components appear as dc quantities [5]. From Fig. 1, the following equation for the system can be derived.
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ENHANCEMENT OF POWER QUALITY BY USING D-STATCOM

ENHANCEMENT OF POWER QUALITY BY USING D-STATCOM

The waveform represents the sum of different sine-waves with different magnitude and phase, with frequencies that are multiples of power system frequency. Harmonics are resultant of electrical machines that work beyond knee of the magnetization curve, DC brush motors, arc furnaces, rectifiers ,welding machines, and non-linear loads that include power electronics equipment including SMPS, data processing equipment etc. Harmonic distortion levels are depicted by calculating total harmonic distortion (THD) that measures the overall harmonic spectrum with magnitudes and phase angles of each single harmonic component [9].
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