Science topics: Power Engineering
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# Power Engineering - Science topic

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I am an electrical engineering student and starting my final year. I need ideas for Final Year Project related to Power Engineering. The ideas i am looking for are supposed to be new i.e., not implemented before in history or they are being done in rest of the world but not in Pakistan.
It will be a big help for me.
Thank you.
Qazi Mansoor Ul Haq You can code in Julia or python if you are interested in designing the inverter controls.
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I am simulating a power converter circuit on Simulink platform. This also include a 400 V AC grid. I am not sure about a generic thumb rule to define the impedance of the cables for this 3ph 400V Grid system. Any suggestions?
As an alternative, you can measure the grid impedance for the 400 V AC system directly. Please check our below publications for in-circuit impedance measurement:
[1] Z. Zhao, "Measurement setup consideration and implementation for inductively coupled online impedance extraction," Ph.D. thesis, Nanyang Technological University, advised by Prof. Kye Yak See, Mar. 2021.
[2] Z. Zhao, K. Y. See, E. K. Chua, A. S. Narayanan, W. Chen, and A. Weerasinghe, "Time-variant in-circuit impedance monitoring based on the inductive coupling method," IEEE Transactions on Instrumentation and Measurement., vol. 68, no. 1, pp. 169-176, Jan. 2019.
[3] Z. Zhao, K. Y. See, W. Wang, E. K. Chua, A. Weerasinghe, Z. Yang, and W. Chen, "Voltage-dependent capacitance extraction of SiC power MOSFETs using inductively coupled in-circuit impedance measurement technique," IEEE Transactions on Instrumentation and Measurement, vol. 61, no. 4, pp. 1322-1328, Aug. 2019.
[4] Z. Zhao, A. Weerasinghe, Q. Sun, F. Fan, K. Y. See, "Improved calibration technique for two-probe setup to enhance its in-circuit impedance measurement accuracy," Measurement, 2021, vol. 185, Art no. 110007.
[5] A. Weerasinghe, Z. Zhao, N. Narampanawe, Z. Yang, T. Svimonishvili, K. Y. See, "Single-probe inductively coupled in-circuit impedance measurement," IEEE Transactions on Electromagnetic Compatibility, 2021, doi: 10.1109/TEMC.2021.3091761.
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Hello,
I have a question regarding the zero-sequence voltage injection in three-phase SSTs with bypassed modules in a failure case. I investigated some literature and it is clear that only the fundamental harmonic can shift power between the 3 arms (for power balance).
A 3rd harmonic is often used to reduce the peak arm voltages (-13.4%). However, I investigated asymmetrical fault cases and a 5th and 7th harmonic can help tofurther reduce the arm voltage by a small percentage like 5% (so less redundant modules are needed):
My question is: Do you know other methods to handle asymmetrical fault conditions in cascaded H-bridges or SSTs? Can I handle grid-imbalances like module faults, since the modules in the phase with an over-voltage have to transmit more power (if no zero-voltage injection takes place)?
I thank you for your suggestions and ideas.
Or do you have experience in three-phase systems with a floating star point?
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Hi,
I am working on tracing current unbalance in HV systems. All papers study unbalance based on simulations which may fail in practical conditions. I'd like to know whether there is any standard for CT/CVT accuracy class used for current/voltage unbalance measurement or not. I have read IEC60044-1 and IEC60044-5 for CT/CVT standards. There is also IEC 61000-4-30 which defines unbalance measurement classes and it is indicated that CT/CVT accuracy may affect measured current/voltage unbalance ratio in practice (which is obviously correct), but no numerical analysis is provided and here my problem arises. Let's say maximum accepted voltage unbalance in HV systems is 1%. A low-accuracy CVT (say 3% class) may cause a voltage unbalance of <1% be measured >1%. In other words a BALANCE system look UNBALANCE or vice versa. Is there any standard that provide unbalance limit + measurement instrument's accuracy class?
Something like:
If you are using a CVT of 3% accuracy class, maximum acceptable voltage unbalance is 2%.
If you are using a CVT of 1% accuracy class, maximum acceptable voltage unbalance is 1%.
(I know IEC61000-3-13 is another standard related to unbalance, but unfortunately I don't have access to it)
Regards
Please take a look at this paper
regards
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I'd like to know the common FACT devices in distribution systems.
D-STATCOM,SSSC,,TCSC,IPFC,SVC and UPFC.
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I am designing a control for bi-directional LLC-SRC DC-DC converter. The converter charges a battery from the grid. But during reverse operation, i.e when the current flows from battery towards the grid, what may be the impacts of current on the resonant capacitor (Cs as attached)? Do I need to wait for the discharge of DC link capacitors (fast/slow anyhow) on both sides? I cannot see any abnormal change or fluctuations during simulations. For practical approach, I am not sure. Any suggestions?
Good question, follow
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I am currently designing a BMS for a 48 V Battery pack of an electric vehicle. One of the major challenges regarding the BMS is to equalize the voltages of the cells (as different cell have different ageing) of the battery pack. How can one address this issue??
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Hi,
While learning about different algorithms such as Regression, Clustering, Classification, etc. in Machine Learning in different domains such as Medicine (Patient data analysis, etc.), Market analysis, etc. I wonder, how these algorithms could be implemented in Power Electronics or Grid Applications? Any ideas?? Are there any datasets available similar to the ones in UCI ML repositories??
In my opinion the AI can be applied in different sector , Computer Versions (Robotic), Automotive sector(Autonomous vehicle's), economics (financial)....etc.
For Grid Applications that you can do it the smart Network for gesture the power Electric or surveying the Sun for the most energy for stocks in batteries to do it With Deep Leraning.
I hope that be Clair. @Ravi Verma
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As a part of Industry 4.0, IoT also enjoys a vital position in smart technologies. However, with respect to power electronics, I have read that privacy over the internet could be a concern. Does this technology benefit us in power electronics /power systems domain? Are there any applications available?
The Internet of Things (IoT) is a concept that refers to a digital interconnection of everyday objects with the Internet. It is, in short, the internet connection more with objects than with people. This fact. constitutes a radical change in the quality of life of people in society, offers a large number of new opportunities for access to data, specific services in education, security, healthcare and transportation, among other fields. Power electronics plays a fundamental role in this process. Give an example. Heating, Ventilation and Air Conditioning (HVAC) systems. The power electronics supports the drive and control hardware of these thermal machines. Allowing the intelligent control of these machines that are responsible for 40% to 60% of the energy consumption of a building. This strategy is a great opportunity to save energy.
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I have seem active power ramp rates defined across 60 second intervals (or a minute), with the corresponding units reading as MW/min or kW/min.
I am working with original active power data that are recorded on average every 7 seconds, and am wondering if I can derive and calculate ramp rates over 7 seconds with units reading kW/7Sec ?
The answer is yes. I suppose the smaller intervals would be better especially in RES systems...But you should always consider the burden of calculations if it is important in your work. It matters to run a time-accuracy trade-off in this regard.
Good luck
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The increase in the trend of distributed generation has led to the formation of community microgrids. What is the best possible solution to connect single-phase loads to a microgrid with 2 level voltage source converter?
I feel one possible solution to connect single-phase loads is to use a 3-phase 4 -wire transformer.
You can use the split DC link which includes two series capacitor in parallel with a large balancing resistor for each of them . This a simple way to provide a neutral point which its voltage clamped at half of the DC link voltage .
Special PWM generating schemes can be used for balancing of the capacitors voltages. But where the neutral current is large, it flows through the capacitors and, hence, bulky capacitors are needed to make the voltage ripple on the capacitors. Also the neutral point usually drifts and becomes unbalanced when it includes DC component. So different strategies for neutral point balancing are reported, usually using the Space Vector Pulse Width Modulation or MPC control.
A better way to provide a neutral line is to add an additional fourth leg, called a neutral leg, to the conventional three-leg converter. The neutral current can be controlled to flow through the inductor so that the neutral point is maintained at the mid-point of the DC link. This allows the phase legs and the neutral leg to be controlled independently, which means the three phases can be controlled independently as well.
Ref :
Control of Power Inverters in Renewable Energy and Smart Grid Integration https://ieeexplore.ieee.org/book/6381785
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I mean devices which uses this effect
Bhupendra Desai, did you carry out reserch about cooling engine with vibration?
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Hello everyone,
I have three questions about connecting onshore wind farms to substations:
1) I know, that larger onshore wind farms are connected to higher voltage levels (110 kV or 132 kV). But which voltage level would I choose, if I only have one wind turbine? does a rule of thumb exist depending of the wind turbine / farms capacity (MW)? A reference to cite would also be nice.
2) I have a wind farm which is already connected to a substation. Another wind farm is newly built and is nearer to the first wind farm than to the substation. Is it also possible to connect the wind farms, instead of the connecting line to the substation?
3) Do you have references for costs to connect wind farms to substations for UK? For example costs per km.
Thank you very much!
Jann
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Hi
We want to build a quadcopter for a research project,but I have trouble choosing the battery,,,i'm looking for one with the lowest weight and highest capacity,and the price doesn't matter!
And i want this quadcopter to be able to work for an hour and it's weight be less than 3.5 kilograms and it's be able to ship(take) thing up to 1 kilograms
thanks for any help possible
You ca refer to " Introduction to Multicopter Design and Control " chapter 4 or flyeval.com
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I am using a 3 phase BLDC motor with current rating of 20 A and voltage rating of 18V. At the moment zero cross detection scheme has been employed in the floating phase for position detection of the rotor while two phases are energized at a time. In the start, motor is commutated for a predefined interval until a specific speed is reached. After that, the motor is commutated normally using BEMF detection method. The problem is sometimes commutation works fine and sometimes not. In other words it is not reliable. For example, i have to play a lot with the parameters so that commutation works fine until smooth BEMF signals are acquired. Still then, the results are not reliable.
How to proceed in this situation? any ideas or references would be appreciated!
... that is, I seem to remember having read about an inductance sensing method applicable at low rpms (and high switching frequencies).
IIRC, this method requires current sensing for all 3 phases (or having only 1 phase energized, reducing the requirements to a single current sensor).
Might be the following paper helps:
They mention some "short pulse sensing technique" that might be what I seem to recall.
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Nominal power and frequency: 55 MVA, 50 Hz
Number of windings on left side: 1 (Nominal voltage: 230.94 kVA)
Number of windings on right side: 2 (Nominal voltages: 41.86 kVA, 20.25 kVA)
Hello Asghar,
If you are modellign an ideal transformer, you can set the turns on each winding equal to the voltage of the respective winding.
If the transformer is not ideal, you have to limit the transformer core flux to the maximum of the core material you are using. The following equation can be used to calculate the number of turns in the primary:
E(rms) = 4.44fNAB(peak)
Then use the secondary to primary voltage ratio times the primary turns to calculate the turns of each winding on the secondary.
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Considering thermal power plants, operational costs, start-up costs of units, are mainly due to the fuel consumption.
I would like to know what are some specific costs of daily operation of a hydroelectric power plant, specially regarding the hydro unit commitment model.
One specific question, is what is the cost of starting up a hydro unit ?
In some papers, an amount of water is related to the cost of starting a hydro unit, how one can specify that amount? Can we represent that cost in terms of discharge of water?
I guess, maybe the cost of starting up is said in terms of water, because, for starting up and connecting a synchronized generator, operator needs to wait till the generator reaches the plant frequency, and meanwhile, some amount of water needs to pass from the turbine which does not lead to power generation.
Is that correct ?
IRENA International Renewable Energy Agency (IRENA) reports average investment costs for large hydropower plants with storage typically range from as low as $1,050/kW to as high as$7,650/kW, while the range for small hydropower projects is between $1,300/kW and$8,000/kW. Adding additional capacity at existing hydropower operations or existing dams that don’t have a hydropower plant can be significantly cheaper, and can cost as little as \$500/kW.
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In the Unit Commitment Problem, for a hydropower system, trying to meet the forecasted demand.
If the scheduled generation ( solution of optimization)
have variations with the demand, say 0.01 MW, is it something practical?
Will it be accepted and operated by the operators? or is it too much?
I do place tolerance because It kind of helps the solver to reach feasible and optimal solution in MINLP problem. As you know, originally it should be an equality equation.
A power system has several power plants. Each power plant has several generating units. At any point of time, the total load in the system is met by the generating units in different power plants. Economic dispatch control determines the power output of each power plant, and power output of each generating unit within a power plant , which will minimize the overall cost of fuel needed to serve the system load.
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I am studying earthing system design for switchyard, substation, street lighting. I understand that fault current level for two earthing system is different. But I am not able to anticipate the effects if two are connected together.
N : Neutral of star point connection is earthed
PE: equipment cabinets, enclosures, and structural steel bonded together and earthed
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What is the function of line traps other than communication?
If power line carrier communication is used for signal transmission through the power conductor itself then only wave trap is required to filter out the noises.
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How to calculate the value of the variables like stray capacitance etc? Is there any standard about measuring them and conducting such study?
It is Reference: 039
Type: TECHNICAL BROCHURES
Title: Guidelines for representation of network elements when calculating transients
Abstracts
This report gives guidance to all experts as well as to beginners who have to deal with any kind of electrical transient phenomena in power systems, how to represent network elements to achieve an acceptable accuracy for their calculations.
Srete
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I want to do a research in optimal sizing in hybrid power system, I want someone to suggest me anew point to do??
The posted items can help you to have a better understanding of the working principle, modelling, sizing and energy management based on optimized FLC of a hybrid energy system:
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Hi all,
I am studying two Alfa Laval brazed plate heat exchangers (BPHEX) used in an ORC power engine (one CB30-40H for the recuperator, and one CH76-100E for the evaporator). More precisely, I am modelling these heat exchangers in the frame of an off-design performance analysis of the ORC engine, and to this end, I would like to know the chevrons angle of the BPHEX.
After reading the Alfa Laval documentation, I managed to find the plates shape and the chevrons angle of their L- , M- and H-type brazed plate heat exchangers. However, they do not mention anything about E-type BPHEX (case of my evaporator).
Anybody would have a hint for me?
Rémi
Dear all,
For the one still interested, please know that E-type plates from in Alfa Laval BPHEX have a chevron angle of 2*beta = 120° . I managed to determine it experimentally, you can use this value with confidence.
Hope it will help,
Rémi
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I want to do switching overvoltage simulation in power system. What are the recommended practices to do the job? Can we do it without any commercial software (e.g build own algorithm in Python)? Thank you in advance.
I recommend EMTP (ATP) software. This is very good software for studying power system transients.
Regards.
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Could anyone kindly provide me a basic level of research paper which gives me an idea of how to integrate a battery or storage system in a simple series APF or in a STATCOM using the Simulink model?
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Would you please explain a bit about infeasible solutions to a unit commitment (UC) problem and what dangers and consequences it may lead to ?
by solution to UC I mean a day-ahead schedule of course.
regarding UC I am studying different paradigms used to tackle this problem. Some conservative approaches like Robust Optimization(Ben-Tal) and Info-Gap ( Ben-Haim). Their conservatism can be justified due to risk averse nature of UC.
For me, as a water resources engineering student, this risk averse and avoiding infeasibility, needs to be explained in a general fashion,
Hello,
As you may know, power systems may be subjected to contingencies that result in forced outages of generators. Therefore, the generators fleet should include a time-dependent minimum spinning reserve for handling such contingencies. Another requirement is the optimization economic operation of power systems. A third requirement is the consideration of the startup time and its related costs, and ramp rate limits of generators. All these constraints and objectives contribute in the secure and resilience operation of power systems. Security constrained UC is then among the methods of realizing secured operation of the generation subsystem with time. Improper UC may force the system to operate in an alert state due to spinning reserve shortage or even an emergency state due to steady power imbalance. You may read the relevant parts of the following publications for more knowledge about unit commitment, power system security requirements, and corrective actions.
Wood AJ, Wollenberg BF. Power generation, operation, and control. John Wiley & Sons; 2012.
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Dear All
Can you provide me with maximum allowable currents of branches in IEEE 33 bus distribution system?
Thank you
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Assume two wind generators are connected in parallel to a bus and supply power to a load demand. The rated power of the first generator is 2 MW, and the rated power of the second generator is 2.5 MW.  You need to build the overall system model including the wind turbines, wind driven generators, and load demand. To maintain the power balance in the simulation, the load demand is the sum of the wind power outputs. Demonstrate the active power output curve with respect to the wind speed in the steady state. You can specify different wind speeds to get the curve.
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good night , do research on broken bars in three phase motors, it was with a 1 HP motor and to generalize the application of the method 'm looking for a database with more powerful engines .
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Any mathematical formulation for decide the limits of GRC and GDB in LFC.
A generation rate limitation of 0.1 p.u. per minute is considered here, i.e.,Δpg≤ 0.1 p. u ./ min=0.0017p. u ./ sec. In Saturation block +/- limits values for GRC.
The GDB width considered is 0.036 Hz. In dead Zone block +/- limits values for GDB.
Excellent. Wishing you great achievements.
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Experts in nuclear power generation can reply
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Now I study in the last year in mechanical power engineering department , I discover this field in this year and i like it , I want to work in this field but i don't know what I can do to be professional in this field,
Solar power is a great field. Some countries are using solar power as a source of energy.
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I am working on partitioning problem and want to show a novel algorithm for network partitioning based on complex network theory. I need this system high quality figure. I don`t have access to this figure.  Any advice? Can anyone send me this figure?
May be this link can be a help
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Dear all,
Generally, when we talk about the large scale of PV penetration in power grid, we associate the term stability. But, in case of  roof top PV system to be connected extensively in the LOW VOLTAGE radial feeder, what are the factors to be focused on? Voltage Parameter violation, energy loss tracking, etc being the ones i pointed out. Others? We don't have to watch out for transient stability issues, do we?
PV solar generator connection should be analyzed for all typical parameters which are common in DG analysis, such as voltage variations, power loss, short circuit, bidirectional flow, protection, power quality, intermittence etc. When it comes to transient stability analysis, which has traditionally been reserved for transmission systems, PV solar generators in LV network are usually not scrutinized in this sense. The broader picture is mainly concerned with the increase in the popularity of microgrids and the capability of an LV network to operate in both standalone and grid connected mode. In this sense, transient stability and small signal analysis are becoming important and are required in order to ensure safe and effective operation of the microgrid. This is mainly because of an interaction of control systems of DGs, switching operations required for transition from standalone to grid connected mode (and vice versa) and low inertia inherent to small DG
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Dear All
Practically, in Direct load control (DLC) demand response programs, the utility has full control over the registered loads? The consumer-side has no control at all?
Thank you
Sincerely,
Registered loads include, typically, pool pumps, air conditioners and electric hot water systems. And yes, the utility has full control over these loads. Instead, the consumers are awarded by a way of financial incentive such as recurring annual payment. The consumer may control the local registered loads in a way that the critical peak is not increased, e.g. the consumer may turn off and/or turn down an air-conditioner which is registered in DLC program. Likewise, as Labib said, the consumer control cannot over write the utility control.
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what's the main use of it other than making an analysis of the IEEE bus system
There are more standard power systems in the IEEE power system society such as IEEE 33-bus and 69-bus systems. When researchers want to validate their novel methods and changes and analyse the effects of the changes they need to compare them with a standard power system. Therefore, IEEE standard systems are valuable references for researchers to test their ideas.
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i had little doubt over the hybrid wave and wind energy turbine system. as when both are combined with common electric grid to transfer electricity. when turbine failure cause any problem to other turbine electric system or else can we operate even one fails. i am not deep into concept but need clarification in this point.
Both the wind turbine and wave are intermittent sources of electricity generation. When integrated together, one could be used as a backup for the other and this will increase the reliability of the integrated system.
Also, note that the total efficiency of this hybrid system will be the product of the wind turbine efficiency times the wave energy conversion efficiency. Hence, the hybird system efficiency will be less that either of them alone.
You can download my lecture notes in the wind turbines and wave energy conversion (WEC) from my profile at:
Professor Yehia Khalil, Yale University, USA
Fellow of the University of Oxford, UK
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after removing some overloaded branches, power system is divided into some groups( each groups might contain generator or not), how can I calculate DC power flow in each single group by using matpower since running DC power flow on the whole system does not converge.
you can use the following GAMS code to solve the problem
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What are the methods for connecting and why?
You can connect two solar inverter outputs (AC) together in parallel, but they must be frequency and phase locked and made to be grid-tie if they are to also be paralleled with the larger power grid. There are many ways of doing this, but a master-slave approach works quite well with one master and up to several slave inverters, all synchronized. It can be done with either analog or digital control.
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I calculated PSD of my function, but the PSD output has too many oscillations; therefore, it's hard to find -10dB threshold. So, my question: Is there a correct way to smooth the PSD or do I just need to take the envelope into account?
Thanks.
Dear Cagatay,
Using the moving average is roughly equivalent to low pass filtering your raw data. The resulting smoothing you obtain on your spectrum is due to filtering out other high frequencies out. Your spectrum do not reflect your raw data any more, I believe this is not your main intention.
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I'm essentially trying to determine the power calculation for the following setup:
I would like to test the hypothesis that using different serum sample tubes have an effect on the test result. Imagine I would like to compare whether the two different sample tubes have an effect on the Troponin result -  I would test the following:
1) patients who have a positive Troponin test, and obtain samples in the two different sample tubes, to be measured on the same analyser
2) serum from healthy volunteers, spiked with recombinant protein
The assay has a CV of 10%, so I would want to make sure I detect if the variance between the two samples exceeds this.  How many patients do I need to recruit? Which test do I use to perform my power calc? Do I take 6 samples (3 of each sample tube) of each patient?
Hi Tom:
First, the belief that at least 30 samples could improve your statistical inferences is a myth, you must to calculate the sample size for a paired design for a given significance level and power, expected effect and expected variability. If you perform the measures with a paired design, this could give the differences significance between the two procedures by paired t test if the response (difference) have a normal distribution or a non parametric test (Wilcoxon signed-rank test for paired samples).
Best regards.
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I have a 4 level signal that need to be power amplified with efficiency higher than 90%.
the levels of the signal are {-3A,-A,A,3A}. assuming in each level, the amplitude is constant until the next amplitude level is switched, what class of amplifier ( or customized power amplifier) can be used to amplify that type of signal with maximum switching rate with high power efficiency?
we know that when we have two level signal, class C amplifier can do this by applying an amplifier and limiter to the input signal and then non-linearly amplify the signal with out distorting the signal (because it is 2 level) .
so is there a generalization to that approach that can keep the (4-level) signal not distorted after amplification?
For audio frequency range, I think class D amplifier is the best solution for high-efficiency application. And there are many integrated chips that can be used to implement easily.
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i am looking for a instrument to measure the efficiency of 1000 KW Inverter
We use Yokogawa 1600WT (it is expensive but it maches to your case) some years ago and results were very interesting and with a low uncertainty. The best efficiency for some inverters is done in a very specific conditions and, under real sun, it is usually worse.
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No power analysis was applied given the study design and they produced statistically significant results. I'm just confused as to whether you can state that a type 2 error was avoided or not for this study design.
IMHO :One cannot avoid either absolutely  type1 or type 2 error in the real world. However one could minimize the errors. Perhaps a pointer to how best it has been avoided would be to evaluate confidence limit .Another would be to simulate a known  analytical model and check the design.
Cheers
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I am trying to model a CHP plant providing 175 MW electrical power 75 MW thermal power using steam. The CHP consists of a combined cycle power plant with CSP without storage providing thermal power. How does this plant fare compared with IGCC plant which uses coal as fuel source ?
I assume you mean a concentrating solar plant by CSP. The combined cycle power plant should be able to approach 60% efficiency (based on higher heating value/gross calorific value) when fired with natural gas and assuming you have reasonable cooling water available. It should have very high (90%+) availability. The CSP plant is highly location, weather, and season dependent and, since you state it will not have storage, will be a highly intermittent source of steam. Candidly, the only redeeming feature of such a plant is its low CO2 output - in all other ways (cost, efficiency, reliability, etc.) it is likely to be poor. The IGCC plant also can approach 60% (again HHV) efficiency on paper but in practice will achieve only 40% at best. Furthermore, the pressurized gasifier will require continuous expert attention to maintain a reasonable availability. The CO2 emissions from the IGCC plant will be more than double those of a natural-gas-fired combined-cycle plant given the combination of the fuel C intensity and the difference in efficiency. However, the fuel should be inexpensive. Quantitative comparisons vary widely, but a consensus view is that power from CSP is more expensive than IGCC which is more expensive than coal which is more expensive than NGCC. However, you appear to only want the heat from CSP, not power, in which case it probably makes more sense if your demand can tolerate the intermittency of supply. Depending on the temperature of the heat you want from CSP, I presume you are aware that there will large quantities of low-grade heat available from the NGCC that is essentially free and not intermittent.
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Hello,
I am simulating a case of vanadium redox flow batteries with carbon felts of thickness3.8mm at 50 percent SOC.Now I am getting an overpotential across the thickness of negative electrode which increases near the membrane.Can anyone explain why this scenario happens?
Should be potential changes near the membrane, reflecting the kinetic barrier for ions to enter/exist the membrane.
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Let's say I want to optimize a new generator location in an existing power system. I need to know how's the system efficiency, reliability, etc with the new generator. Can I use ETAP or PowerFactory to do this? I usually use Matlab but I don't want to build my own load flow or reliability evalutaion codes. Can I use those software to calculate it?
Dear Johanno
Of course that you can use DIgSILENT software which I recommend to you. It has Power flow module and Reliability module. The location of a new generator is not easy problem. It is complex and there is no atumatic procedure in DIgSILENT to give you the right location and rated power of new generator. It depends of network configuration and loads in the system. So you need to use some other optimisation metod and check it in the DIgSILENT since in do not hav such module. The closed one is Optimal power flow module and reliability module. There are mayn different modules but location of generator can be check it manualy in iterative prosec depending what do you want to minimize the loses or maximize the reliability of the system with new generator.
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I am trying to maximize the generated energy form a certain power source (Irregular one), so I want to reach the maximum power transfer via defining an optimal load impedance. It happens that the optimal Load is not pure resistance (as the source itself has some reluctance/capacitance), is there a certain Power Electronic circuit such as Boost Converter that can be designed to "Emulate" that optimal LOAD.
Thanks
Hello Mustafa,
In order to transfer the maximum amount of power from a power source you have to apply the “Maximum power transfer theorem”.
Please, suppose that your circuit has a power source with its internal impedance connected in series with the load impedance Rl+jXl.
The above mentioned theorem demonstrates that the maximum transferred power is obtained when:
-           Xl=-Xs
-           Rl=Rs.
This means that Zl=Zs* (i.e. the load impedance is the complex conjugate of the source impedance).
Finally, if the reactive part of Zl is constant, the maximum transferred power occurs when Rl=sqrt[Rs^2+(Xs+Xl)^2] which means that Rl is equal to the absolute value of the whole network impedence.
Regards,
Roberto
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Dear All,
There has been numerous researches and studies related to optimization or economic dispatch algorithm used for the optimal power flow in various power grid ( standard IEEE as well as some other case studies as well.)
As i have understood, the problem is however still in the part of real world implementation. I am trying to indicate the challenges and problems while implementing those developed algorithm in real world power grid after successful simulation or modeling.
For example:
To implement an optimization algorithm in a physical grid after successful modeling,
2. The central control unit is equipped with forecasted load demand for next hour or half an hour based on the nature of Grid load curve. and so on.
3. Based on the forecasted load demand, Central control unit dispatches the command to individual Governers of each generating stations to change the Power output accordingly.
4. The central control unit operate in closed loop system and thus capable of real time load sensing. Minor mismatch caused due to variation in forecasted load demand and actual load demand is covered by slack bus. For, exceptional major deviation, reiterations of load flow equations might be required.
5. The communication between the central unit and respective generating units could be facilitated via already existing OPGW  system.
thus, in order to implement any optimization algorithm in a power grid, major additional requirement is of properly customized central control unit.  Apart from that, other requirements like communication, Pg change and real time demand sensing could be done by utilizing the already existing setup like- OPGW, Governer, Power analysers, etc.
This is the summary of my observation and understanding. I would be grateful for any correction/ suggestions as i am planning to implement GA based optimization in a real world power grid. I have already done the simulations and now trying to get things together for real world implementation.
Regards,
Bishal
Dear Bishal,
In reality I have not seen any real time system (experiences in India and Middle East) with intelligent algorithms like Economic Load Dispatch. Dispatch control is made manually based on short term load patterns for their operations. Transmission companies generally log the load data on a periodical basis for the purpose.
Regards
Sujith
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There is a confusion in defining repair rate. From Richard Brown's book, Power Distribution Reliability, it is said that repair rate is the inverse of repair duration, which is defined as the mean time needed to repair the system SINCE it fails (page 164). But in the Markov process example (page 204), he used repair rate as the rate of transition from switched state (1b to 0 and 2b to 0) to normal state, not from the fail state to normal state (1a to 0 and 2a to 0). I attached the screenshoot of his book.
Hi Johanno,
Frankly, in the material you have exposed, there is no statement about the repair rate. Basically, you are right, one should take into account the sum of the two times for passage from nb to  na which  (for n=1) equals to
THEAVERAGETIME1 = 1/\sigma1 + 1/\mu1,
so, the rate equals, according to the author's definition  the inverse value, i.e.
THEREPAIRRATE1= \sigma1 \cdot \mu1 / ( \sigma1 + \mu1).
It is very hard to guess, why the sigmas are omitted. Suggestion - ask prof. Brown:)
Best regards.
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What I am trying to signify here is, in case of power grid of NEPAL (My homeland), the load demand is always higher than the total generations from all Major generating stations (hydro power plants mostly). So, all power plants usually operate in their maximum possible capacity to meet the demand to whatever extends they could (Total load demand is curtailed by load shedding through load dispatch center such that Pd=Pg-Pl).
Now, the problem is, the transmission line loss is still very significant (around 8%) and I originally thought of following the CONCEPT OF OPTIMAL POWER FLOW to minimize the transmission loss. However, under above mentioned condition of generators already being fully utilized, I am finding it hard to rationalize the whole concept of optimization for this case.
Is there still some way I could impose the concept of optimization or optimal power flow under these circumstances?  I hope I have explained the problem clear enough. Any help would be great.
For reference, Attached herewith is the approximated ETAP model of grid itself.
Regards,
Bishal
I understand your problem. All the OPF and all other advanced techniques are for countries with surplus power. A few  years back our state is in similar situation like yours. Now the officals say we have surplus power and so many solar and other projects are coming. One day your countryalso may be having surplus power. Please remember, new theories and technologies are for the entire mankind not for just one country.
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I'm planning to work on optimization of switch allocation in existing distribution network. I have no working on distribution system before. My question is, what are the considerations in moving a sectionalizer from a location to another? Can I just move sectionalizer near the substation to the end side of the network? Is a sectionalizer chosen to be placed in a specific location only?
Dear Johanno
If you want to put sectionalizing switches in the distribution network you need to set optimization function and what do you want to optimize? Do you want to minimize losses, or do you want to maximize reliability (minimize reliability indices, SAIFI; SAIDI; CAIFI; CAIDI; ENS ...) including the capital, installation and annual O&M costs.
As Desta Zahlay already said you need to set objective function and solve it. The solution will be the number and location of sectionalizing switches. There are may paper about that matter.
Srete
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Dear all,
I am trying to run a load flow analysis of relatively unknown power grid. However, one of many problem i am facing is that the network consists of 132 kV branch or line and 66 kV lines as well. I could opt for using the lumped representation of the 66 kV segment but it would make the analysis more unrealistic. Also, if i try to consider two different voltage level for the load flow analysis, i might face the problem of Per unit representation.
How could i proceed? I would highly appreciate any help in this topic.
Regards,
Bishal
1. You can do LFA using per unit values. What is the problem you have with pu values?
2. There s a way to include even transformer tap changes using an alpha factor.
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Any ideas on features/factors that could make cooperative transactive control more attractive to smartgrid an local community energy markets ?
Hi Gerro,
Don't know if this helps, but transactive energy management for biogas as a residential fuel is becoming somewhat common in Indian villages.
Transactive energy management with a focus on electricity from a microgrid is still uncommon. Maybe it will gather momentum in the future, because experience from the biogas ventures have been quite good.
Cheers !
-Sanjay
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I am trying to design a model in MATLAB which takes lesser computation time. I have seen how it is possible to design averaged switch models for unidirectional buck, boost and buck-boost converters. I was wondering how the same could be done for bi-directional DC-DC converters.
Hi. If you use the SimPowerSystems circuit model, it's computational time is very much. You can solve this problem with its mathematical modelling.
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Can anyone please share an experiment based on the PM800MG Power meter with 18Amps contactor with overload relay.
visit the schneider electric site, you will get many ideas - not sure  what you are interested in . you can do a lot with. If you have ethernet module that's even better
Be aware Soffware is needed for advanced functions - probably free for 1to1 application
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i am working on project in which we will be converting a gasoline powered engine to E100.To increase the compression ratio we have decided to change the piston as we have decided to increase the diameter of the cylinder.So what changes should we make to the connecting rod so that it withstands the increase in force,torque etc.We don 't want to change the diameter of the pin as it would require us to make changes in the crankshaft as well.
There are two types of forces acting at the connection rod:
1. Pressure induced force Fp from combustion. Fp is a function of the pressure characteristics in cylinder and the acting surface, in this case the piston upper section surface (as a function of the piston diameter). Fp acts on the connecting rod as compressive-force, leading to compressive stress. in addition, the piston pin and the crank pin are stressed, mainly by shear stress and bending stress. An increase of the piston diameter and of the compression will lead to increased cylinder pressure, which increases Fp.
2. Inertia forces that stem from the movement of the cranktrain components. For your question, the translational inertia force Ft might play a major role. Ft leads to tensile stress in the connecting rod as well as shear stress and bending stress in the piston pin and crank pin. Increased piston diameter might lead to increased moved mass that rises Ft.
For dimensioning the connection rod (but also piston pin and crank pin) the forces mentioned above should be considered.
Kind regards,
Mario
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In RF sputtering system, there is control panel in build with the system, which is used to control and adjust the cathode power, here my question is that what is Reverse Power (RP)...? while we are applying the power (for example 100 watts) means, reverse power is showed that 20 watts. I thought that the target power of 100 watts should not be there in the cathode,
Kindly give your valuable ideas and suggestions for this above-mentioned questions, which may be useful for me.
It should be reflected power, not reverse power,
RF powder is coupled to the target capacitively.  If there is an impedance mismatch, then the power applied (say 100 watts) will not be fully coupled with the target, and there will be reflected power which you see as 20 watts in your case.
In other words this is known as max power transfer theorem, which is taught in electronics.
For a good coupling of power to the target the reflected power should be zero watts. Sometime in some systems, due to some mismatch there is some problem or the other, and you see some reflected power.
Be careful if you see a much larger value for the reflected power (say > 25 watts, or it keeps on increasing), for an applied forward power of 100 watts, it is not good for the system (power generator) to see a large value of reflected power.
In you rf system if your have the tuning and coupling knobs, then you should properly adjust them for achieving good impedance matching, so that you see a minimum of reflected power (say zero watts). Which means all the forward power of 100 watts which you have applied is efficiently transferred to the target.
K. Sreenivas
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I am planning to use timing belt for the power transmission. In my application shock loading is exist. So I wanted to know which belt having more shock resistance, made from carbon-fiber or from Kevlar? (If both belts having same power transmission capacity)
Carbon fibre is rigid,but somewhat brittle because carbon fibre is often mixed with other materials.
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while doing power flow analysis of a radial distribution systems using backward forward method,how to apply DG with bidirection
I have little confidence in doing bidirectional flow for a radial system. In a radial system, power will flow in only one direction. Well, the power will flow from the side of 'generator' to the side of the 'load'. If you have only load at the end of the radial system, you cannot get the opposite flow.
Even if you have a generator (say DG) on the load side, but if the DG size is smaller than the load, the power will flow in the same (traditional) direction (from generator to load). But if your DG size is bigger than the load which is located at the same place, then, some power will be pushed back from that DG into the grid. So, it's either the regular traditional power flow or opposite.
But, if you have a meshed network for the distribution system, the power will flow based on where your DGs are located and where you loads are.
I hope this helps!!
Regards,
Jeremy
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i am working on project in which we will be converting a gasoline powered engine to E100. I want to know maximum compression ratio that can be achieved within  the safety limits (using bajaj discover 100cc dts-si engine for the same).
The compression ratio of an engine is a given engine parameter defined by the maximum cylinder volume (engine displacement) and minimum volume (compaction space).
Formula: ε = (Vh+Vc) : Vc
The maximum compression depends on the quality of both fuel and engine control unit of the motor. Usually the compression ratio will be between 6:1 and 10:1 for a combustion engine using high quality petrol. For dts-si-motors it can be assumed to be higher for 98 octane petrol (around 12:1).  Because of the better knocking resistance of ethanol it could be higher, but as mentioned in the first paragraph, it is a defined motor parameter.
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There are some SKF type high pressure feed pumps that work under conditions: Pout= 200 bar, Tout= 247 oC.
I want to know that when this pumps should go under repairs.
For any pump there should be pertformance parameters like temerature , pressure , flow rate etc these parameters should be monitored all the time in order to know the working health status of the pump. So, you should know from the pump datasheet the nominal values of these parameters and by using metering devices you can evaluate it.
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I need a reliable failure rate and mtbf database of different power supplies, but I can not find any database with this information.
Dear Julen,
What does "Power Supply" mean to you?
SMPS to charge a smart phone?
ATX-Style Power Supply for PC?
Laboratory reference supply 10V/1000A?
High-voltage-supply 3kV/100mA to charge capacitors?
As much difference as you can see in these supplies, as big are the differences in a predicted use case and the according lifetime.
I'm rather sure there is no database that contains reliable data, especially if you ask for MTBF which is an uncommon parameter to estimate the durability.
I suppose you meant MTTF (Mean Time To Failure) as you want to know how long the device will last once being commissioned.
A far more accurate number is the design lifetime in operating hours that usually a manufacturer gives for certain operating conditions like current or load profile and ambient temperature.
Some manufacturers make a statement in FIT-rates which is a statistical number on how many devices will fail "in time" while "time" refers to 109 device-hours, multiplying operating hours and devices in the filed. Less helpful for a single supply anyway...
I do not agree with the test suggested by Donald as the high temperature can easily trigger failure modes that do not occur during usual operation at lower temperatures. Think about electrolytic capacitors that will die at 150°C almost instantly but operate thousands of operating ours if kept below 80°C.
The acceleration factor remains undefined, thus the test result are void.
It comes down to this:
Breeding an egg at 28°C takes 5 days, resulting in a healthy chicken.
Breeding an egg at 30°C takes 4 days, resulting in a healthy chicken.
Breeding an egg at 32°C takes 3 days, resulting in a healthy chicken.
Breeding at 100°C will NOT get you a healthy chicken in 5 Minutes!!
Cheers - Martin
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If we have a rectangular function for voltage for a certain waveguide,and we have the rise and fall time of that, is the power output change by changing the rise time ?why?
Hopefully you may familiarized with a Periodic waveforms are the most common of all the electrical waveforms as it includes Sine Waves. So there square wave of any real periodic function turn out into output power, then the key finding is the use of LaplceTransform to compose fuction , by multiplying two fuction in time, Ｖoltage=f(t) and Curret=h(t) and associate with  convolution property to determines the Output of a System under zero state response. The output power is also set as y(t) to find  the impulse response y(t)=f(t)*h(t), and integrate the right hand side in time domine .Moreover rectangular Voltage Waveforms are similar to the square wave waveform above, the difference being that the two pulse widths of the waveform are of an unequal time period.
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I am designing much better ferrite-core high frequency transformers than I can buy.  The core is wound with two layers over it's entire magnetic path length, The winding is coherent, i.e.: all parts of all windings have the same lay, and the same lead. I will attempt to measure the time lag between a sudden increase in load current, and the reflected current in the source.  Are there parameters of the transformer, that should allow me to predict the delay?
Hi Newt,
I think it should be possible, provided you represent the high frequency distributed parameter model for each winding accurately. The well known Bergeron transmission line model can be modified to serve the purpose, though the usual branches of the standard Bergeron form would have to change, (other than the usual distributed series resistance and inductance, and shunt-to-ground capacitance and admittance) primarily to include additionally
• inter-turn capacitance and insulation admittance for all windings,
• winding-to-core capacitance and insulation admittance - particularly for the winding wound immediately on the core.
• winding-to-winding capacitance and insulation admittance - particularly for windings formed one-on-another annularly.
The magnetization inductance and core loss resistance have to be suitably set for the ferrite core that you are using.
Once all this has been done, the time lags and delays can be estimated, and the detailed model can also be simulated on PSPICE or other software.
Hope that helped !
-Sanjay
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One of our generators output current has unbalanced current.
What is cause of generator unbalanced current?
What is its cause possibly?
Six similar Genset connected to one bus. One of those Gensets have unbalanced current.
Is it possible its because of air gap of the failed phase?
What is solution for this problem?
Hi Omid,
Pavel has made a couple of points that I will tend to agree with. Here is some food for thought - you may consider as to which of these fits the bill !
1. I think you can rule out unbalances on the load side altogether, as Pavel rightly mentioned.
2. I would also rule out winding-to-ground (winding-to-core, in reality !) fault or winding-to-winding fault (fault between two turns of different phases within the same shared slot, in reality !), because such occurrences are sure to be picked up by the generator protection with the huge negative and/or zero sequence currents that would flow.
3.  My "most probable" guess will be an inter-turn short within the same winding (of course, this could occur simultaneously in multiple phases, though with lesser probability). This can occur between turns of a winding that either share a slot, or are taped together in a bunch. The other location where this can be observed is in parts of the overhangs, where we observe a criss-cross of several conductors within a small physical space. The broad cause for this is insulation degradation with aging, which may be accelerated due to moisture or contamination in the air, overheating (due to high load current) over prolonged periods of time, etc.
4. My "second most probable" guess will be a non-uniform air gap (the air gap "above" the rotor cylinder being marginally more than the designed value, and that "below" the rotor being marginally less - both occurring simultaneously), which is something that you seem to have come close to guessing yourself ! This too is an aging effect, but due to erosion at the support bearings, which leads to the rotor sinking a bit from its original coaxial position, thereby creating a "larger air gap above and a smaller below" the rotor.
Both #3 and #4 are effects of aging, and the unbalances will "take time" to aggravate to levels that are detectable by protection systems. Both require shut down of the unit, servicing amounting to replacement (insulation or bearings), and reinsertion to service.
In both cases, when you take the machine out and do a simple OC test, the rms EMF recorded in the three phases will be different. In #3, additionally, with the rotor at standstill, the impedance recorded for the three phase windings will have significant differences.
Now since you know the history of your generator, you are the best judge as to how to proceed with the investigation, and what to suspect !! :-) :-)
Hope that lengthy posting was of some use...
-Sanjay
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What are the strengths and weaknesses of Simulink to simulate power systems?
SimPowerSystems, now promoted under “Simscape Power Systems”, is a very useful and versatile power system and power electronic simulation software. Its main advantage is to be fully embedded into the Simulink software. The Simulink software is probably the most used simulation software for control systems.  Most car manufacturers use Simulink to test their systems and even to build actual car control software, using tools like Simulink Coder. The majority of readers of this article (most probably) have cars that actually runs Simulink-based controllers without being aware of it!
This Simulink integration makes SimPowerSystems very attractive for the simulation of power systems and power electronics because of the ease of controller design and connection to the electric part of the system.
I would like to add that I use SimPowerSystems as a reference for my own solver design since more than 10 years now because it is very accurate.
One noticeable disadvantage of SimPowerSystems may be its computational speed. With large power systems in particular, the state-space solver used by SimPowerSystems can become much slower than traditional solver based on the nodal admittance method, such as the ones used in EMTP-RV and PSCAD.
As part of Opal-RT Technologies, I developed a solver called State-Space-Nodal (SSN) which can solve this speed issue in SimPowerSystems. As the name say, this SSN solver is a nodal admittance based solver at its core and this is the main reason of the speed improvement over state-space methods. This is particularly important in real-time applications where SSN can make simulations with consistently low simulation time steps.
Finally, I would like to mention that SimPowerSystems as well as EMTP-RV and PSCAD belong in the category of Electro-Magnetics Transients (EMT) software and are designed to visualize voltage and current transients occurring during faults for example. Their simulation time step is in the 20 to 50µs range typically for this purpose. They are typically used in systems of less than 1000 busses, otherwise they would be really slow.
EMT simulation software are to be distinguished from Phasor Simulation software, often called Transient Stability (TS) simulation software. In TS simulation software, only the RMS values of voltage and currents, along with machine angles and powers, are computed using a time step of 1-10 milliseconds.  Because this time step is several order of magnitude superior to EMT methods, TS methods can run simulation of networks much larger than the EMT ones, even in real-time. Examples of TS softwares are DigSILENT, PSS/E, PowerFactory, ETAP and ePHASORsim (which is developed and sold by Opal-RT by the way). ePHASORsim is rated at 50000 busses in real-time and I am quite sure that other TS softwares can run much bigger cases because they don’t have this real-time constraint.
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mathematical model of inverter
Mathematical, based on +ve, -ve, zero seq. analysis using measured value of current and voltage of individual phase would be used to find load unbalance and fault type. Refer papers..
...
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If the positive terminal of 12 volt battery is connected to the +6 volt and the negative terminal is connected to the -6 volt supply, Does it leaves any side effect on the battery? if yes please discuss the effect.
By establishing a 0 V level, you have established a ground.  The battery will be happy across the -6 v, +6V connections unless you have inadvertently established a second ground in the battery, e;g. via a metal case.
On a different topic I sent you a question via your gmail account.  I hope you can respond soon.
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Suppose the main power supply is down. The standby generator now supplies power to loads in its bus. Is it possible to make a standby generator supply power via the distribution feeder to another load points as well? If it is possible, what are the requirements (beside enough capacity)?
Standby generator can supply power to the load, but operational constraints & equilibrium constraints should not be violated.
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Hello,
This question is about the dimensioning of the fuse to be placed in my application of inverter. I have calculated the current rating considering various derating factors.
Now, I want to dimension the fuse as per its I2t rating. I amaware that Fuse I2t should be less than the Semiconductor I2t etc. I am looking for some document which has some steps to calculate and co-ordinate I2t of fuse with that of the application.
I will be grateful for your help.
Regards
Aalok
Aalok,
Pick up any book that describes fuse coordination at load ends - the principles are more or less identical (other than motor starting currents).
-Sanjay
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Would like to know how to model a constant power load in SImulink/Simpowersystems. I'd like to be able to simply change the power requirement of the load which is being powered by two boost converters. Any help would be great, thanks.
Cheers guys.
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is there anyone who can help me to explain if do  not consider line impedance effect only consider effect of load , so how to design droop parameters to get more accurate power sharing concept among parallel inverter?what are the parameters will be effected ?
its quite diffcult for me to understand the power sharing and droop concept anyone will try to expalin it .
System stability, with Negative feed back..........
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Please provide me help and related literatures for designing  a coupled inductor with coupling coefficient about 0.4 to 0.5 in laboratory.
Dear, Varun Chitransh,

I’m sorry, but I’m not a specialist in this issue.
Regards,
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How does it affects the accuracy and convergence of a load flow study? Why is it typically 1.6? Does it have something to do with the golden ratio?
1. The convergence in gauss-siedel is very slow when compared to other load flows (like newton-raphson, FDC, NDC). so, In order to increase the convergence speed , acceleration factor is used. too low value of alpha(acceleration factor) will delay convergence. but very high value may skip desired solution/some times divergence. alpha should be chosen based on trail and error  method. Generally alpha will be  in range of 1.6 to 1.8. However  it changes from one power system study to another. if system considered is well connected better to use Newton-Raphson Method.
2.  Now a days no one uses gauss-siedel load flow. FDC is being used in online studies. if  accuracy matters ,use of  newton raphson method is mandatory.
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Can someone kindly introduce some references (new references will be better) and new lines of research about chaos and its applications in electrical power engineering?
Dear Dr.
Chaos Theory has been successfully applied to predict the long-term behavior of numerous biological systems using a
technique known as a “Recurrence Plot”. This same method of application should prove useful in Systems
Engineering as well. Recurrence Plots reveal long-term and emergent behavior in complex systems when specific
criteria are met. This technique may be used in Systems Engineering in such diverse areas as Systems Architecture to
predict emergent behaviors in Complex Systems and Program Management to predict the long-term health of a
complex project among others. The utility of Recurrence Plots in the field of Systems Engineering will demonstrated
as well as establishing the requisite criteria and the technique itself. Future work as well as other approaches and how
they compare will also be addressed.
You can see the following ref.
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