A Five-Level inverter are gaining attention, exertion are being directed toward attenuating the device count for increased number of output levels. A novel topology for Five-Level inverter has been proposed in this paper to attenuate the device count. The operating principle of the proposed topology has been illustrated and mathematical formulations suiting to output voltage, source currents, voltage stresses on switches, and power losses have been eliminate. Comparisons of the proposed topology with existing topologies acknowledge that the proposed topology significantly reduces the number of power switches and associated gate driver circuits.
For regions where this clause applies, the requirement shall be met by a base station transmitting on a single RF carrier configured in accordance with the manufacturer's specification. In addition, for a BS operating in non-contiguous spectrum, the requirements apply inside any sub-block gap. In addition, for a BS capable of multi-band operation, the requirements apply inside any inter-RF bandwidth gap. Emissions shall not exceed the maximum level specified in tables 6.3 to 6.6 for the appropriate BS maximum outputpower, in the frequency range from ∆f = 2.5 MHz to ∆f max
For example, an audio system contains a microphone, a CAM2, and a power amplifier.There are 3 controls that affect the volume of the microphone through the audio system speakers; the MIC input control, the CAM2 MASTER con- trol and the volume control on the amplifier. How should these be set for best operation? Since the MIC control is the closest (electrically), the microphone should be turned up the highest while still allowing enough “headroom” to increase the microphone volume if necessary.The MASTER control should then be adjusted to produce an out- put signal that lights up the red output meter indicator only on loud peaks and the volume control of the amplifier should be set so that the volume of the speakers are as loud as could possibly be needed. By setting the volume controls this way, the amount of undesirable hiss noise, which is produced in all audio equipment, is minimized. This is the correct theory in setting up system gains (volume levels). However, there are some other factors that ought to be considered. For instance, the individual input control should not be set so high that it requires the MAS- TER control to be set near zero to keep the output signal level out of the red.There has to be a reasonable amount of “control range” to the MASTER control to make it useful. In this case it is a good idea to reduce the level of the individual input control so that the MASTER control can be rotated over a wider range to provide some overall level control. During normal operation of a well set up audio system, the MASTER control is used to increase or decrease the overall system level as the noise and audience increases and decreases. However, large changes in the necessary volume level should be adjusted at the power amplifier. If the signal outputlevel of the CAM2 is near its maximum (as indicated by the outputlevel meter) and the desired speaker level cannot be achieved, even with the power amplifier volume at full, it indicates that the power amplifier or the size/quantity of the speaker is not ade- quate to cover the desired area.This type of problem cannot be corrected by system volume control settings.Trying to get more volume out of a system under these circumstance can only lead to distorted sound since the audio equipment will be pushed beyond their designed maximum operating conditions. Correct the problem by getting more suitable equipment for the job.
For the past several years theories and concerns have churned about the radiation levels in cell phones. There has been speculation that cell phones can cause radiation poisoning leading to brain or mouth tumors. People who have gotten brain or mouth tumors from unseen cell phone radiation give off have used their devices for a time period of ten years or more. However there are companies that have lobbyist whose sole purpose is to convince the general public that cell phone radiation is not a concern. “CTIA, the wireless industry lobbying association stated “scientific evidence has overwhelmingly indicated that wireless devices do not pose” a health hazard”. Although there is not concrete evidence whether or not cell phones are linked to cancer, some countries have taken preliminary precautions. What I suggest is to keep your cell phones SAR level to come at or under 1.6 W/kg and follow the tips given in this paper. There is accumulating evidence that cellphones that operate on GSM networks emit significantly more radiation than do cellphones operating on CDMA networks. The modulation pattern is different for CDMA and GSM phones, and some scientists think GSM pulse modulations may have adverse biological effects. Cell phone radiation is an obstacle our generation must come to face so we don’t have a rise of cancer in years
The amplifier is designed for an impedance of 50 ohms. If the antenna-feeder devices are matched to a resistance of 50 Ohm, and the VSWR in all operating ranges does not exceed 2.0: 1, then the amplifier can work without additional matching. If the VSWR exceeds 2.0: 1, it is recommended to use additional matching devices.
ABSTRACT: There is much significant recent advancement in the area of power electronics applications to the photovoltaic power system. Photovoltaic systems are becoming more widespread with the increase in the energy demand and it also reduces the environmental pollution around the world. Out of different structures of multi-level inverters, Cascaded H Bridge (CHB) inverter is more suitable converter for PV applications since each PV panel can act as a separate DC source for each cascade H bridge module. A mathematical model for the photovoltaic panel is developed and implemented with the multilevel inverter. There are many limitations in extracting power from renewable energy resources. To minimize the power demand and scarcity we have to improve the power extracting methods. Multilevel inverter can be used to extract power from solar cells. It synthesizes the desired ac output waveform from several dc sources. The main objective of this paper is to study the5-level and 7-level Cascaded Multilevel Inverter. In this paper the different parameters (like voltage, current, THD) in 5-level and 7-level Cascaded Multilevel Inverter are observed. By these observations it can be seen that the total harmonic distortion is reduced with the increase in the levels of Cascaded Multilevel Inverter and also as the levels increases the output approaches to the sine wave. Simulation works are done in MATLAB/Simulink.
It is seen from the comparison that the LC compensator is very adaptable in high power and short distance applications but the modified LLC compensator is the one of the dominant compensation circuit which is accessible for short distance application due to its flexibility in operation but they are not suitable for long distance applications. Double sided LCLC is very efficient in long distance transmission as they reduce the voltage across the capacitive plates in a suitable range. They can be used for applications in power levels from watts to kilowatts range. Although these topologies possess high efficiencies but they have large air-gap and under misalignment conditions between the coupling plates. The CLLC compensation on the other hand has decent misalignment ability at a reasonable air gap distance due to reduction in its inductor size which is a major progress in CPT technology. In this paper the advancement and introduction of different CPT system and their compensation topologies have been summarized in a symmetric manner which is helpful to establish research framework of compensated topologies for capacitive power transfer for future applications. The drawbacks of each topology are also included which would help in modelling and improving the topologies for the further research.
In the Nigerian power system, with a large interconnected rapidly growing system, the Independent System Operators (ISO) and the unbundled Transmission Company of Nigeria (TCN) face different operational challenges including economic load dispatch of their generating units. The 28-bus model of the Nigerian grid used for this study is made up of 10 generator buses and 18 load buses with fifty-two (52) 330kV transmission lines distributed across the country interconnecting these various buses. Three (3) out of the ten (10) generator buses on the network are hydro, with Egbin a thermal power station of capacity 1100MW being the largest . It can be seen that grid energy mix of the Nigerian power system is predominately hydrothermal in nature with most of the hydro resources (Kanji, Shiroro, Jebba) situated in the northern part of the country and the thermal units domicile in the south, due to the abundance of fossil fuel, i.e., natural gas in the south. In this paper, the solution to the economic dispatch problem of the Nigerian power system using genetic algorithm is discussed.
Scale can also affect the existence of an IPO with regard to efficiency. This would lead to the expectation that IOs that have a smaller number of members are more likely to have a linked IPO. This is because it is easier to compromise and reach a consensus with fewer states. Furthermore, the little number of states, logically, makes the IPO smaller. It is, therefore, easier to create and maintain, as well as both cheaper and more efficient. This would mean that small IOs have IPOs more often than big IOs. The same efficiency effects as mentioned in the above are relevant for power: having a smaller group of countries does make it easier to make decision, but it also means their decisions do not have much impact, because the policy only applies to a small region. A big scale, on the other hand, would have a lot of impact but because of the large number of different countries an agreement would be hard to achieve. Big decisions would hardly be made. As a result, the middle scale of countries would be most effective and powerful. These considerations lead to the next two hypotheses:
used in commercial, industrial and power plant applications and most of the pumps are operated by constant speed drive systems. The purpose of this study is to investigate the pump performance, characteristics, of centrifugal pump with variable drive system. For this study an experimental setup of the setup was constructed to achieve the centrifugal pump performances such as Head vs Discharge, Efficiency vs Discharge, Input power vs Discharge curves. In the variable drive system a dimmer-stat was installed in experimental system. The test rig used in the present investigation was well planned, designed, fabricated and tested. All the components of the experimental test rig were fabricated in department workshop. The results shows significant change in performance of the centrifugal pump when dimmer-stat is used for speed variation.
As depicted in Fig.1, the TH72015 transmitter consists of a fully integrated voltage-controlled oscillator (VCO), a divide-by-32 divider (div32), a phase-frequency detector (PFD) and a charge pump (CP). An internal loop filter determines the dynamic behavior of the PLL and suppresses reference spurious signals. A Colpitts crystal oscillator (XOSC) is used as the reference oscillator of a phase-locked loop (PLL) synthesizer. The VCO’s output signal feeds the power amplifier (PA). The RF signal power P out can be
approaching of the dispersion curves for operating and higher-order modes, the decrease of an outputpower of DRO occurs, and even there is a failure of an oscillation as a result of a mutual coupling of the ORS modes [4, 5]. However, there are a lot of successful applications of mutual coupled modes in RF/microwave devices, such as narrow-band bandpass ﬁlters for mobile communications systems , highly resonant wireless power transfer adapters , etc.
In the past few decades, biomass gasification has emerged as a promising route to efficient utilization of biomass, a renewable energy source which is widely available in tropical countries like India. This involves conversion of the biomass, a solid fuel, into a gaseous fuel called the producer gas. The producer gas can either be burnt in a burner for thermal applications such as furnaces or can beused in an internal combustion (I.C.) engine as a substitute for petroleum based fuels, to get motive power or electricity. being increasingly looked upon as viable alternative to provide electricity and motive power to the remote rural areas of our country. Availability of electricity can, in turn, act as a catalyst for promoting rural industrialization and development. While commercial systems of this kind are already available, many organizations have put inefforts to make simple low cost gasifiers, fabricated locally. In the same spirit Navree Energy Research and Information (NERI), an NGO, developed a gasifier-engine system and tested it in the field for running a flour mill and an irrigation pump, for more than a year [1, 2]. Gasification is a process converting solid/liquid fuel into gaseous fuel, known as producer gas, without leaving any solid carbonaceous residue. The producer gas is the mixture of carbon monoxide, hydrogen, methane and nitrogen. Abundant quantities of agricultural wastes like subabul woodchips, coconut shell, groundnut shell etc. are produced worldwide every year and these are now underutilized. The major portion of these wastes undergoes natural decomposition resulting in production of various green house gases and other environmental problems. Biomass gasification is one of the biomass conversion technologies to produce a combustible gas mixture (called producer gas) using agro residue. Biomass gasification can be effectively utilized for decentralized power generation and thermal applications. The gasifier is essentially a chemical reactor where various complex physical and chemical processes take place that include drying, heating, pyrolysing, partial oxidation and finally reduction as it flows through it. Pyrolysis is the heating process, which produces both charcoal and tar and combustion is complete oxidation of fuel. Gasification process is in between pyrolysis and combustion. Gasifier can be broadly classified into three according to the gas flow direction, that is, up draft, down draft and cross draft gasifier times [3-7].
The above differential and algebraic equations can be solved using a suitable iterative numerical algorithm such as a higher order Runge–Kutta or trapezoidal integration method to minimize the round-off errors in calculation. Although the DG system model shown in Figure 4 is a simplified one and the Equations (2)–(6) only consider the positive sequence components, undoubtedly, the model and solutions still can provide insight into the dynamics of the system behaviour under fault conditions in a very straightforward way . It is worth noting that typical distribution network configurations and models are much more complex compared to the one shown in Figure 4. For the unsymmetrical fault conditions, a negative sequence network that omits all positive-sequence generators needs to be considered under such conditions. For example, for a single-phase-to-ground fault, the negative sequence network is connected in series with the positive sequence network while, for a phase-to-phase fault or a phase-to-phase-ground fault, the negative sequence network is connected in parallel with the positive sequence network. Additionally, the lines have been modelled as lumped longitudinal impedances whilst, in reality, unbalanced impedances that also consider transverse parameters need to be taken into account. Equations (2)–(6) also neglect the mutual coupling between the phases and the presence of transverse parameters. Therefore, simulation tools such as EMTP, PSS/E and PSCAD/EMTDC can be used for the dynamics analysis of the power system [30,31]. In our study, we use the power system commercial software platform PSCAD/EMTDC because it is capable of modelling the dynamics of a complex electrical system in details under normal and fault conditions. 4. Investigation of Effects of Doubly Fed Induction Generator (DFIG) Tidal Current Turbines
The advances in information technology and the increasing requirement of Very Large Scale Integration issues have resulted in a rapid development of several optimization algorithms and techniques. Low power consumption and smaller area are some of the most important criteria for the DSP systems and high performance systems. DSP systems have less sensitivity to component tolerances and environmental changes and the dynamic range of the system can be increased by floating point arithmetic . Multirate processing arises in many fields of digital signal processing.
These kinds of conflicts are exacerbated because exclu- sions zones must be implemented as general rules, without regard for the differences in wireless services. If, for example cell phones are discovered to cause an EMI problem in a nuclear plant then all cell phones, in all frequency bands and at all power levels must be excluded. However, per- sonnel will often discover that their cell phone creates no interference, making the exclusion zone seem arbitrary and needless. This may lead some plants to issue ‘blanket approval’ for the use of all cell phones—a strategy that presents undefined risks to the operation of I&C equipment. The fact is that originally cell phones operated in the 800 MHz band, using RF power of up to two (2) watts. Today, most cell phones still use the 800 MHz band but are also equipped to operate in the 1,900 MHz band, where the maximum power is one (1) watt. Further, the 700 MHz band frequencies have already been auctioned, although equipment has not been deployed there yet. The
feedback (lower values of C), but at a cost to signal-to-noise ratio (SNR). To illustrate how feedback strength (as encoded in Acket’s constant C) affects the harmonic content of the SM signal, we repeated the simulations for different values of C representative of three different feedback regimes , very weak (C = 0 . 1), weak (C = 0 . 73), and moderate (C = 1 . 93). The results are shown in Fig. 6. In the very weak feedback regime (C = 0 . 1), the SM signal, barely visible in (a), is almost purely sinusoidal with second harmonic about 25 dB below the fundamental. However, the fundamental itself is about 15 dB below the fundamental in the weak feedback regime (C = 0.73), resulting in a commensurately lower SNR. Correction of longer pulses, for example the pulse of Fig. 5 (a) time-scaled to a width 200 μs, would require drive currents outside the laser’s operating region, and is therefore not possible. Shortening the pulse width on the other hand may compromise sweep range in applications being optimized for maximum frequency sweep. Frequency linearization in such applications is therefore limited to pulse widths of the order of the laser-submount thermal time constant. Since the time con- stant of the thermal circuit is fixed at manufacture and assem- bly time, tailoring the drive pulse width and swept frequency range to suit specifications or experimental requirements must be done at the design stage via modeling. Deliberately increas- ing the laser to submount thermal resistance, for example using an epoxy instead of indium interface, may educe the full potential of the thermal modulation characteristic of Fig. 3(a) at shorter pulse widths.
There are many methods presented in the literature for modeling PV mod- ules. Among these, the single-diode model and the two-diode model are widely adopted  . A comprehensive review of all modeling techniques is also available    . Most of the models are focused on monocrystalline and polycrystalline PV modules using different techniques. For instance, the sin- gle-diode model proposed by Gradella  presents a power matching algorithm by varying the series and shunt resistances simultaneously, for accurately fitting the characteristic curve at standard testing conditions. The diode ideality factor is arbitrarily chosen. This concept is extended to two-diode model . There are many other models presented in the literature that use conventional methods based on datasheet parameters   . All these models accurately predict the I-V characteristics for monocrystalline and polycrystalline modules, whereas they fail in a fair prediction of the characteristics of thin film solar cells. Other methods presented in literature are based on optimization and soft computing techniques. Even though these methods envisage the behavior of PV modules accurately, they are highly complex. A modeling approach for PV modules based on amorphous silicon solar cells  considers an improved single diode model with two additional parameters.