Power Engineering - Science topic

Interesting

Thanks Kiuling Lai, I have contacted the secretary but no response from my email till now. Still waiting for the acknowledgement of my email.

Hello Ahmed Yahia Yaseen

Here are two possibilities:

Power Engineering Journal

International Journal of Electrical and Power Engineering

I am unsure about how long to wait until publication. Maybe you need to contact the editorial office to get that exact information. Some journals give electronic publications before it appears in print. These would be considered to be like having traditional publications and I would include those in my CV or job application.

Qazi Mansoor Ul Haq You can code in Julia or python if you are interested in designing the inverter controls.

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.

Or do you have experience in three-phase systems with a floating star point?

Dear M.Amin Mehrab

Please take a look at this paper

regards

I also need the link or data of maximum allowable (limiting value) currents of IEEE 33 bus system.. It would be great...

D-STATCOM,SSSC,,TCSC,IPFC,SVC and UPFC.

Good question, follow

Have a look at https://au.mathworks.com/videos/how-to-develop-battery-management-systems-in-simulink-part-1-bms-overview-1574416523692.html

https://au.mathworks.com/solutions/power-electronics-control/battery-management-system.html

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

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.

Dear Mohammad Royapoor

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

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

Bhupendra Desai, did you carry out reserch about cooling engine with vibration?

Please take a look at these attached sites

Good luck

https://www.researchgate.net/publication/334817993_Optimized_Placement_of_Onshore_Wind_Farms_Considering_Topography

You ca refer to " Introduction to Multicopter Design and Control " chapter 4 or flyeval.com

... 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.

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.

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.

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.

Dear Hossein Mahdinia Roudsari

Can you please answer me for this question ?

Link: https://www.researchgate.net/post/How_many_Earth_Pits_are_required_for_the_neutral_and_Body_of_Transformers

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.

It is Reference: 039

Type: TECHNICAL BROCHURES

Title: Guidelines for representation of network elements when calculating transients

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

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:

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

I recommend EMTP (ATP) software. This is very good software for studying power system transients.

Regards.

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.

Excellent. Wishing you great achievements.

Solar power is a great field. Some countries are using solar power as a source of energy.

May be this link can be a help 

https://www2.ee.washington.edu/research/pstca/pf118/pg_tca118bus.htm 

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

Dear Ahmad

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.

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.

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:

Hope this helps answer your question.

Professor Yehia Khalil, Yale University, USA

Fellow of the University of Oxford, UK

you can use the following GAMS code to solve the problem 

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.

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.

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.

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.

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.

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

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. 

Should be potential changes near the membrane, reflecting the kinetic barrier for ions to enter/exist the membrane.

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.

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.

I hope this can help you!

 Regards,

Roberto

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

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.

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.

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

Bishal,

To add to Sudha's reply, you actually should convert everything to per-unit and execute power flows only in terms of per-unit.

It has been shown that convergence of a power flow is not assured if you run the iterations in mutiple absolute units.

Once results are available post convergence, they can always be scaled back to the correct absolute units.

-Sanjay

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

Hi. If you use the SimPowerSystems circuit model, it's computational time is very much. You can solve this problem with its mathematical modelling.

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

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

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

Carbon fibre is rigid,but somewhat brittle because carbon fibre is often mixed with other materials.

Gadaram,

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

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.

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.

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

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. 

I hope this might help you....

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

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 

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 !

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

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.

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..

...

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.

Standby generator can supply power to the load, but operational constraints & equilibrium constraints should not be violated.

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