Science topics: Power Systems Modelling
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Power Systems Modelling - Science topic

Simulation of Power Systems as a whole and of each separate component
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Why the fault current ?
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I think this is because the energy transfer takes place at sub-synchronous frequency (below 50Hz) unlike the normal case at 50Hz, and thus the energy flow (power (voltage and current)) all look distorted.
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I want work on my project in the field of "Microgrid." I need a test system of microgrid in digsilent or matlab simulink. If anyone here has this file, please give me.
Thanks guys!
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You can also use Simscape Power Systems to Simulate Microgrids
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Hi, I need a power system model with 2 - bus, 2 - machines and a long-distance HVAC transmission line.
Would you mind providing with me all the necessary parameters of the system?
Bergeron line models will work for me.
Your help is greatly appreciated.
Thank you
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There is a book "Power System Stability and Control" Prabha Kundur has simple networks
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I want to to generate the power trace input file for HotSpot.
I am using Wattch power simulator. Wattch doesn't generate the power trace for directly.
can any one help me what changes required in wattch source code to generate ptrace file
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Hello Bala,
I am trying to generate the power trace file through Noxim. Can you please let me know whether you figured out the answer as to how or not.
I have the power by each FU in each cycle.
Thanks in advance.
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Hello. I am working on the voltage stability issues of an actual large-scale wind power connected power system and am trying to simulate the occurences of three-phase short circuit faults at different parts of my extensively modelled grid mainly in places of high wind penetration. The problem is that whenever I am simulating 3-ph faults at some busbar that should bring down the voltage to almost 0.15-0.25 p.u. at it, the system is becoming unstable right at after the voltage drop or at the instant of the clearance of the fault with the RMS simulations throwing up errors like 'System Matrix Inversion Failed' or 'Equation System could not be solved. Check control conditions.' This problem is disappearing at relatively less voltage dips at the concerned buses (at around 0.3-0.4 pu and above). So I wanted to know if this is an issue with how the grid has been modelled in actual such that at severe voltage dips it becomes unstable, or is it because of an underlying issue in my modelling of the grid which I may have overlooked in the process. I have followed quite efficient dynamic modelling procedures of the wind turbines as per IEC standards and the conventional generators as per the usual standards. Any help regarding this would be much appreciated.
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Soudipan Maity : Were you able to troubleshoot the problem ? As, I am also facing the similar problem in PowerfFctory. Kindly let me know.
Regards,
Deepak
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Can anyone share the PSS/E (Power System Simulation for Engineering) user manual?
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Hi! please see the attached file below in V30.
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For the efficiency calculation of dc-dc converter (In Cadence environment), I am still wondering whether to use Average or RMS value? They give different results. Some of publications and books use the integral of the instantaneous power divided by the period (which is RMS value at the output but average at the input. Others calculate by average value in both input and output and others use RMS.
I checked many typologies (buck, boost, buck-boost) and they bring out a difference in the power efficiency using RMS and average value. In the experiment, the power efficiency seem to be more correct using average value. 
So does anybody know for sure which one to use, and please explain why?
Really appreciate your sharing!
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I think Vrms and Irms are always valid. P=Vrms×Irms is true for both constant as well as for variable values. P= Vavg×Iavg is valid only for pure contineous dc both voltage and current. However in case of inductor for contineous currrent the average and rms is always same.
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Is there any code / package / script to automatically generate single-line diagrams from PYPOWER/MATPOWER casefile or IEEE CDF formats?
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Matlab now has a toolbox for graph theory and complex networks.
i used that toolbox to convert MATPOWER data to a graph, and then generate a plot.
it was useful for me when i wanted to visualize different distribution networks i was working on.
keep in mind that distribution networks don't have loops. so the graphs were pretty neat. but for a large meshed system, the graph would look ugly. matlab wouldn't go out of its way to make a neat graph (with no lines crossing).
the code i wrote throws different kinds of errors everytime i run it, and everytime i debug it or do something to fix that particular problem.
if you're a matlab expert/novahoo, i can share that code with you. you're going to need to look under the cover and debug an error when you get one
otherwise, wouldn't recommend it
you can write your own code. the key matlab commands are:
buidl a graph with:
my_graph = digraph(......)
or
my_graph = graph(.....)
and then
plot(my_graph);
in my code, i tried to color code the different nodes, and represent the impedance or flow size on a transmission line by the line's thickness
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Hello All,
I am working on HVDC VSC converters in DIgSILENT power factory. I have developed the grid and the DSL models of generators, controls and the VSC converters. But, when I run the simulation, it says something on inner-loop iteration reached for some models. I want to know how to resolve this error in DIgSILENT power factory. I have asked this question in the customer portal, but it didn't help me much. They suggested me what I already knew and have tried. I can send the pfd file if required.
I appreciate your help.
Thank You
Anand Prakasha
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Hi Im tuning 4 VSC stations for a HVDC grid, modulus optimum and symmetrical optimum. works????
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Basically, Power World Simulator has been pretty popular for Energy Market Simulator Modeling (Educational Purpose) due to the incremental cost parameters in generator module and many more facilitation. However, the Evaluation version only permits the 12 bus system for any sort of power system modeling or simulation. So, for a larger power grid, it could not be a solution.
Does any other software provide a platform to model such simulator which could be used to model the mechanism of day ahead electricity market that would comprise of bid matching and LMP provisions?
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This is an exciting prospect. To determine the tools necessary, it may be appropriate to determine how you would use a model. A question may be, what type of fidelity is needed and how does that relate to execution time?
Execution time may be relevant if there is an intent to include statistics. For example, if the model is to be used to predict pricing to establish a trade plan, there are many aspects that have probability distributions. Ultimately, there will need to be a decision (calculation) based on something like the highest expected value or a trade-off of expected mean and variance. To address these opportunities, Monte Carlo methods could be used which suggest many runs would need to be made for a wide variety dimensions. An alternative is to build an analytical model including the statistics which would provide a single calculation to obtain a decision. An advantage of the analytical model is that with some analysis, a reduced system could be produced that would have the potential to significantly reduce the calculation type.
There may also be combinations of these where the analytical model could be used to determine an optimal system reduction that may fit a commercial electrical design tool with a minimum number of buses.
Of course, electrical generation and distribution is only part of the model. The amount of consumption and the associated values will also drive the price. Predicting consumption will be an interesting challenge even though there is a lot of data. And these two models are obviously correlated: As prices go up, some consumers will drop off, as environmental conditions change, the consumption will change along with the value to the consumer.
Due to this interaction, an analytical tool may have significant value.
As such, a Matlab like tool may be called for.
I have performed this for large water distribution systems.
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If the real-time steady state load data of substations at sub-transmission level (for e.g., 66 kV) is available, how can we aggregate the loads to the substations at 220 kV or 132 kV transmission level? The motive is to eliminate the the 66 kV substations and below in the power system model with no loss in accuracy. Thanks!
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Hi, Using a load model is very difficult, since it depends on what the physical characteristic of your load really is for the accuracy of the results. The other important aspect that is vital is the type of study you want to perform. These two aspects are what tell you what is the approach you can take. When you are referring to a dynamic analysis, what type of study do you want to carry out:
-Rotor Angle Stability
-Voltage Stability
-Frequency Stability
The type of study is important because they have different analysis time and from there to know which load model to use.
You can consult the book Power System Stability and Control of P. Kundur and the paper Definitions and Classification of Power Systems Stability that can clarify you.
The subject of the load is a really beautiful and controversial subject in the studies of electrical power systems. In my personal experience carrying out transient stability studies, not taking the proper model of the load has generated incorrect results, such as generators that are motorized when this does not happen.
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Hi everyone,
I want to model a solar PV in Digsilent. I have all the state equations as well as the output equations. However, I have no idea about modeling in Digsilent. 
So, do I have to write a code or can I simply connect blocks like in Simulink to create a model? I do know there is a model of PV already in Digsilent but I want to learn more in depth about modeling,
Cheers
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You need to use DSL script routine for PV called "Common Model StatGenController" for inverters with all data. and also PLL Phase measurement devices for inverters
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Dear all ;
Am working on MINLP to minimize the total power losses of the network.
All the used equations were typed correctly.But when i run the GAMS code it gives this error : Infeasible solution. Reduced gradient less than tolerance?
I need assistance in that error ?
Best Regards.
Amna
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  • Try to solve your model with a different NLP solver
  • Try to solve it with a global solver. This may give an indication whether feasible points exist at all.
  • Provide a better starting point. The default starting values of zero are often not appropriate.
  • Provide better bounds and look at the scaling of the model.
  • Try to solve some smaller instances of the model.
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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)
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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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Dear all,
Can anyone share a multi-area power system model built in PSAT to me please? I used to use the kundur two-area system, but for now, I want to try some other multi-area systems.
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Can you elaborate on what you need as the Nigerian Power grid keeps expanding almost yearly. The present Grid is around 55 buses. You can get the 330kV SLD online and model on PSAT.
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Hi all I'm looking to model power flow through a large battery in GAMS where the battery can either charge, discharge or store the energy given parameters of P = 1MW, E = 4MWh. I have a table of power output and corresponding SMP price of electricity for each time slot in order to maximize profit and minimize wind curtailment. 
I currently am using the following constraints: 
Constraint1(t) .. MaxFlow(t) =l= Charge(t,'Power') + Discharge(t);
*Setting constraint that battery can either charge or discharge
Constraint2(t) .. Charge(t,'Power') =l= StoragePower;
*Power flow in to the battery will be less than the Power Capacity of the battery
Constraint3(t) .. Discharge(t) =l= StoragePower;
*Power flow out of the battery will be less than the Power Capacity of the battery
Constraint4(t) .. StorageLevel(t) =e= Charge(t,'Power') *( 0.1667 * eff) - Discharge(t) * (0.1667 * eff);
*Energy in the battery is equal to the energy in - energy out
Constraint5(t) .. StorageLevel(t) =l= StorageEnergy;
*Energy in battery cannot exceed the energy capacity
Constraint6(t) .. Used(t) =e= Discharge(t) * 0.1667 * eff;
*The energy used is what is discharged * time * efficiency
Constraint7(t) .. HourlyRevenue(t) =e= Used(t) * Charge(t,'Price');
*hourlyrevenue is equal to the price of electricity * energy
ObjectiveFunction .. TotalRevenue =e= sum(t,HourlyRevenue(t));
When I run this code the answer returned is stating it's infeasible. I'm currently unsure if I have too many or too little contraints for the problem to be solved. Any help/advice would be greatly appreciated.
Kind regards,
Ciaran
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Can anyone recommend me a good software tool for simulating smart grids with high penetration of energy resourses? I have heard that EMTP, ETAP and Neplan have this potential. Is that true?
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I recommend using ETAP. It's helpful and user friendly. You can simulate AC and DC system at the same time in the new version ETAP 16.
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Dear All
Does anyone know and can sent me a link for free software which can be used for thermal analysis of cable - ampacity and temperature computation around the cables in different environment (ground, water, air, concrete pipe.) I know that there are many commercial software from CDEGS, EATON-CYME..... but I need easy free software to eliminate manual computation.
Thanks in advance
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We did a manual calculation in air before in
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Dear colleagues,
I develop my PhD Thesis in ECONOMICS about ECONOMICAL OPTIMIZATION OF ONSHORE WIND PARKS, and my research aims the objective developing an algorithm for calculating the economical gain in the life cycle of a wind energy onshore project through the correlation of wind velocity (m.s-1) and energy production (MWh.year-1) in order to increase competitiveness and management success of wind parks. The model to be developed will use a “Cost Correction Factor” which takes into consideration the wind velocity.
What do you suggest to me???
I hope to hear you.
Wagner Oliveira
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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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Hi,
I have a power system model in Simulink (not SimPowerSystems ). Goal is to do a trajectory sensitivity analysis w.t.r a parameter variation.
Question: How to find related Jacobians using matlab.?
Thanks in advance.
Best regards,
Amirthagunaraj
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Thanks for your valuable suggestion.
I really appreciate it.
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Generally, load and price uncertainties in power system are modeled via stochastic programming or robust optimization methods. Do anybody know other methods to model uncertainty in power system?
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Dear Amin,
Thanks a lot for your valuable suggestion for interval optimization approach. I'll read the suggested papers in order to know this method.
Best for you,
Sayyad
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I have assumed a industrial load which has three processes [A B C].
A process is meant for Arcing Process operating for 2 continuous hours.
B process is meant for Boiler Process  operating for 4 continuous hours.
C process is meant for Cooling Process oprating for 2 continuous hours.
this is modeled as Matrix in Matlab as [X] equals to below matrix:
[ 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ---------24 hours
  0 0 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 --------24 hours
  0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ] --------24 hours]
1 represent that any process will be ON at that time schedule.
0 represent for process to be  OFF.
1st row represent  A process.
2nd row represent B process.
3rd row represent C process.
In Industrial load , loads/processes can operates only on  if previous unit completed their process. i.e C  process will be turned ON only after completion of B process. and B will be turned on only if A process is completed.
every process in industry will consume electricity for producing some output material .
So the cost of that material depends also on electricity consumption charges. so I Want to optimise the turn ON/ OFF  time schedule  for minimising the cost paid to electrical utility for a dynamic peak Pricing in which high price is charged for using electricty during peak hours.
kindly Help
With Regards
Madhusudan
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I'm designing a 5 kW and 115 rpm permanent magnet synchronous generator for a direct drive tidal turbine. I'm going to use concentrated winding.
I have seen that many authors prefer symmetrical configurations (like 10 poles and 12 slots) but by other side many commercial in-wheel motors (low speed applications) use 46 poles and 51 slots.
The disadvantage I already know is a lower torque compared to a machine with q=0.4 (the 10/12), but on the other hand the LCM is very high so the ripple torque is very low, and the THD is not so severe, so I think it could be a very good option to avoid vibrations problems and ensure a very long useful life that is something very important on this project.
I'm waiting for your comments, thanks a lot!
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Can anyone help me in finding the optimal cost function in model predictive control of machines. How are the 6 voltage vectors calculated from the 2 level vsi and used in finding the optimal cost function?
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I am trying to implement Model predictive torque control of pmsm, but not able to implement it successfully. can anyone help me out with the matlab code for the torque control part.
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Hello, 
I read a paper titled "Cognitive Relay Networks With Energy Harvesting and Information Transfer: Design, Analysis, and Optimization" (link attached).
I have some difficulty in understanding equation 29 and Fig.3 and Fig. 4. 
More specifically, in eq, 29, since the relay in energy constrained and has no energy of its own then I am unable to understand that from the circuit power Pc is obtained? is it obtained from the harvested energy? or it is assumed that the relay has enough stored power for circuit activation? what is the considered value of Pc in the paper?
How they have obtained the results in Fig. 3? Lets assume the results from Fig. 9. where the optimal sum rate at  Ps=30 dBm=1W is 3.5 bps/Hz (when d1=0.5) and circuit power is 0.1W then the energy efficiency according to 29 will be EE=3.5/ (1+0.1) = 3.181. However, in Fig. 3 for Ps=30 dBm=1W  the EE is less than 0.01. How these values and graph is obtained?
Any kind of help in this regard will be very much appreciated.
 
Regards
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Anyone? Any help?
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If we have two parallel DC-boost converters connected to the common load, and If the droop control is properly adjusted to insure voltage regulation and equal current sharing end keeping the circulating current within the limits, then what are other possible causes making this system unstable?
Truly Yours
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Hi Mustafa,
I totally agree with you. Master-Slave mode has single point of failure. Moreover, the two converters may be located at different physical locations, making communication between them impractical. In my experience, I have not seen any issues with droop-based implementation or a very recent decentralized approach that I'm working on. I have implemented them in experiments with four such converters in parallel, without any issues.
Cheers
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My project is to optimize the location of statcom to improve the voltage stability in a given system data using genetic algorithm.First i did a nrlf and later manually optimized the bus at which voltage is below rated value by integrating statcom into nrlf at that particular bus.Now i am trying to optimize it using genetic algorithm.Iam trying to use the 'optimtool' present in matlab to do this.For this i need to write the fitness function.I have a little idea on how to do it (as i am trying to maintain voltage stable then minimizing the deviation in it should come under the fitness function) but i am unable to relaize how to write it.So i would love it if any one can help me with this issue.Thank you in advance
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Kishore you can use some voltage stability index as your fitness function. Thus you can use the system parameter  and the nrpf  solution in your code.
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is there an example of modeling Synchrophasor in PSCAD 
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Yes?
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Can anybody help telling what is step size of power increament for an 1100 MWe PWR while we raise the power level to 70% of full power to 100% of full power. Similarly what can be step size for power decrement, while lowering the reactor power from full power to shutdown state?
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55MW/min (or 5% of nominal power/min) is not a step followed by a pause. It is the rate of increase in power that may maximally be used for , say, Westinghouse type PWRs. The increase is smooth because the control rods are withdrawn at a certain speed (i.e. its own small steps are repeated at a certain rate) allowing the power to increase continuously. In the early life of a reactor there will be more frequent pauses in the increase to monitor a large number of variables.   The 5%Pn/min is the max rate allowed, the design is such as to not permit control rods to be withdrawn faster. Slower yes, faster no.  Pauses are placed at ertain power levels , depending on the manufacturers preference or e regulators requirement. Examples could be at 5%, 30%, 70% of Pn. 
Decreasing power can be abrupt if for some reason a fast shutdown is required. This is called a reactor trip and it may be triggered by a range of events, either in the reactor itself, or elsewhere in the plant (eg a turbine trip will often cause a reactor trip).  It is done by releasing the control rods so that they drop down and stop the chain reaction as fast as possible.
One can also slowly reduce power by inserting contral rods slower.  This depends on the power regime required of the reactor.  When load-following there will be slow or slower reductions in power. 
If you are a lay person with an interest I suggest you obtain reading matter at libraries and search further yourself. This forum is not the place for a course in reactor operation ! 
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Dear All
can you please tell me if the PDF of photovoltaic (PV)'s generated power can be as the attached Figure? To me its suspicious since the PDF value goes to around 3.  I have plotted it based on  equation and data  derived from "A Probabilistic Modeling of Photo Voltaic Modules and Wind Power Generation Impact on Distribution Networks"
Thank you
Ahmad
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Dear Ahmed, Normally the data of irradiance taken over a long time for each hour follows a beta distribution. The final distribution normally has a bimodal nature with a smaller peak at a lower irradiance value and a larger peak at larger irradiance value. 
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where and how to get the IMPACT (IGBT Model Parameter extrACTion) software pack?
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I encountered the same question, as the link that paper referred does not work. 
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Out of several DC-DC converters available, i wish to know which converter will be maximum efficiency
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I would suggest an MPT switched Resonant cycle ZVS controlled converter such that both input current and output voltage is regulated to match source impedance and load charge, under varying wind conditions.
When demand power exceeds supply  then efficiency  drops dramatically without input current regulation.  MPT usually operates near 80% Voc input voltage but drops with available input power unless input is current regulated.
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I have to start researching about  "Integration of Off-Shore Wind Energy Conversion Systems" but I am confused what parameters to research for? 
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thanks guys
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I have implemented a SMIB in simulink and created power swings in it. The next part of my work is to develop a power swing blocking scheme. For that i have thought about 2 schemes: 
Differential power based: i have problem understanding schemes, as to why are we even going for differential power and regression. Predicting future values will always have some errors so why go for it when we have real time signals.
Moving window average: I have difficulty understanding this approach as to how to decide the window and calculating indexes.
If anyone has worked on these, please help
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Hi, I think this article will be helpful for your research
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How much percentage of load can be given by a DG in radial distribution networks?
If any reference papers or standards are there, kindly give me a suggestion.
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DG can take the load of the entire feeder and even export into the substation if you size your DG source for this.  We have done this at our electric utility.  Our only issue was that we noticed a voltage rise on the feeder due to our load tap changers on our substation transformers.  In other words the mechanical LTC's on our transformers were not fast enough to compensate for the increase in voltage caused by our DG's on the end of the radial feeder.    That is the short answer
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How ca n I draw a curved of receiving-end voltage magnitude as a function of load?
10-2- Please see the attached files.
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hi
please  see  the   attached  file
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Hello All,
I spent all morning searching for the error solution on google, so Mathworks and here. I attempted every potential solution I could find: delays, solver changes, saturation, tolerance. I attached the Simulink Power Systems model I have for the verification of my masters research.
While I noticed it originally I dismissed it as I thought Simulink was programmed better with the initial value set, I have narrowed the error down to the voltage measurement origination from the battery model, both the internal and external voltmeter. 
Does anyone on here have any idea what settings are required to circumvent this simulation error? Thanks in advance.
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a) the error traces back to the battery control subsystem, from the battery voltage measurement, and nothing to do with the super-cap yet at least. 
b) checking my super-cap block I have no parallel capacitors.
c) I did change the solver from ode23tb which I used successfully for the equivalent simscape model. It was throwing that error for that as well
c) both with my prior equivalent simscape, and through my research having a power gui block within each subsystem is allowed. 
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In 3-phase 230/63 kV power system model (File attached) i want to change these parameters for CT current reconstruction.
(1) Remnant flux (-85%)  - ( 85%)
(2) Fault inception angle (Different values between 0-360 )
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Hi Muhammed.
I wonder if the value of 90 [T] of the remanant flux density is realistic !
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does anybody know what is the effect of increasing the stages of ring oscillator on power consumption and frequency?if we increase the stages power must be increased or not?and also about frequency
please do me a favor and help me  
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i want to regenerate behaviour of constant PQ-loads from Fig.5.a from chapter-2 of this book(Wind Farm – Impact in Power System and Alternatives to Improve the Integration);Despite much effort i cant regenerate that.please guid me.
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Zahir,
Just as a clarification, what do you imply by "regenerate" ? 
-Sanjay
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there is a dc grid (metro line) which we are trying to regulate its voltage by means of energy storage systems specially suppercapacitors. because of long period of simulation using the real converter with IGBT and switching issues is not an option so we are forced to use the average model. there are some papers which represents buck and boost converter average model separately. i was wondering if we could use these model for our bidirectional converter or we should rewrite an integrated model. 
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If your grid is DC then you just connect a capacitor to it and that will regulate it over the short term. I don't see any alternative to switching regulators over a long term. Capacitor or battery storage is insufficient for say days or weeks of storage of that sort of energy. Or are you talking about regulation periods of seconds or minutes? I don't follow why you are considering capacitors over the 'long term'. As I wondered earlier, how long is 'long' in that context?
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Hi,
I am simulating (by simulink) a distribution network feeder which consists of PV generation site and load. my simulation is too long at time domain so it requires a phasor simulation type (in the configuration parameter of the powergui). However, some of the elements in the model require a discrete simulation type. Running the simulation for the feeder model using a phasor simulation type gave me an error.
May I know how do I go about solving this problem? Any help or advice would really be greatly appreciated!
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thank you Samundra Gurung 
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If in upper distributed substation and transmission, inner consumption feeds from Aux transformers while it’s located nearby power transformer, we can feel that the transformer is under of more tensions and having much short current,
LVAC circuits in the substation panel
What are the other solutions in this case?
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maybe i can help you but need more explanation what you want exactly!
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I am trying to catch the electrolyser, storage and compressor cost even from quote but for a bit large case and also if I move from size to bigger  size how I can scale the cost based on the big size?
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maybe i can help you but need more explanation what you want exactly!
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Hello,
This question pertains to Matlab simulation. I will be grateful in case anyone knows the answer.
Attached .docx file is a Simulink circuit of a inverter simulation. In order to implement close loop control of inverter, I first make it work as rectifier and trying to do its PLL and current control loop implementation. In this quest, I am applying a voltage through a grid and modify it to another level by transformer. I am not able to figure out that after putting any Kp and Ki values, why does the input current waveform shape is not symmetrical? Can any one help me to find the problem? In another file, I have attached Voltage (Upper) and current (Down) waveform taken from grid. The corresponding scope is marked in .docx file.
Regards
Aalok
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Try using Yn instead Yg on the transformer and connect the source N and the transformer N together.
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I am working on optimization of transformer parameters and need expert's advice on this one specifically please guide me.My team has introductory level experience on this FEMM tool.We  need to present simulations for any type of transformer modification.
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Dear Pranav Vyas,
FEMM is a free software which is able to do many types of simulations as it can be controled by LUA scripts. Have a look at the attached files, I have used the script file to show the torque evolution of a PM motor. Unfortunatly, I have no script about transformers. Keep in mind that any ordres which are provided by the icons can be achieved with a LUA script. LUA script is not limited to FEMM and you have to download the LUA script documentation associated to FEMM and also the general information about LUA script.
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I have a network that is failing to converge due to reactive limits . I used the power triangle calculation to determine the MVAR after having the power factor. 
For example, 10MVA  generator with 0.9 pf means the maximum power is 9MW and 4.35 MVAR. If I use this calculation then the reactive power will be very high for the network. 
When I check other models that don't have convergence problem , the total reactive power is very small about a third of the total reactive power. What are the limits that can be used for the reactive power to be used for calculation if there is no data for the machines? 
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I think you should verify the bus and line data.
In bus data, make sure that one bus is slack bus having no reactive power limits. There may be error in entering the voltage. When you don't know the voltage at a bus, take it 1.0 pu.
In line data, the reactances must be realistic, there may be some or one line having very large reactance due to typing error.
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Dose sampling frequency of  100 kHz achievable in  pratical engineering?
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The sampling frequency should be greater than twice of nominal frequency. In HVDC transmission line, the nominal frequency is zero. So, a sampling frequency of 10 Hz with a time period of 100 milliseconds may serve the purpose. This will provide 10 samples per second.
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I am searching [pu] data of a 5 MW DFIG generator for my simulation which i am going to perform on NREL 5MW baseline wind power plant.
However, i have the pu data of a 1.5MW DFIG generator and the simulation is running well with some controllers.
plz provide the data sheet if anybody have.
Thanks and regards,
-Ganesh
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Please have a look at the attachment. 
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Hello Researchers, 
I need high resolution say, a measurement interval of 15 mins - 30 mins solar radiation data for my research. Most of the hourly data archives have average hourly solar radiation which don't accommodate the variation in horizontal direct beam radiation (looks like a smooth deterministic curve). I need to see the deviations in radiation due to cloud and other obstructions if any.    
Please comments your suggestions. Thanks in advance!
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I think this paper authors works with the same field measurement that you are looking for:
Regard.
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if we have electricity power with high penetration of renewable energy and i want to use the excess power to produce hydrogen. can anyone help me with new tariff for excess power since we want to encourage all electrolyser to produce hydrogen at off- peck periods?  
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Dear Abdullah,
I suppose there is no single answer to the question, as especially dedicated tariffs depend on the energy provider, the potential power consumption and the availability of the electrolysis to warrant for really consuming a noteworthy portion of excess power along with the possibility to regulate the consumption accurately.
It will most likely not be too promising to create hydrogen as electrolysis does not provide good efficiency and generating electricity by fuel cells is just as bad.
Fluctuating supply also will make it difficult for the electrolysis to operate stable.
If you want to create the hydrogen to store energy, batteries will be the more efficient, cheaper and more flexible solution.
Cheers - Martin
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I need to valid test system of Radial low-voltage unbalanced distribution system. Each one of the Lines & loads in this system is an impedance (as R & X ).In this test system, the real & reactive power can be defined or not.The important cases at the required test system are:
1-Radial Distribution system
2-Low-voltage(220-240 V)
3-unbalanced in load side
4-Impedance values of lines & loads
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hI
I presume that this is typical RDN(Radia Distribution Network) at  the secondary distribution feeders supply residential and commercial customers at 120/240/440 volts.
In general, the distribution system is the electrical system between the substation fed by the transmission system and the consumers’ premises. As for  f the current case the voltage level  is set for 220-240 V, it is require to maintain requirements for such type distribution in order to guarantee consumers power rate requirement mainly the proper voltage, loading  and reliability issues.
RDN unbalanced are prone for Dynamic change in imposed load, High R/X ratio, and contain also extremely large number of nodes and branches.
You might find Ladder network methods implementation in some section of  the system in order to finds suitability and practical application for single source radial structure networks with high R/X ratio;
You may also use  SVC or Series compensation at substation fed in order to regulate voltage and  Reactive power correction.
i suggest to follow   the below link as well...
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I am working on modeling of weak grid (with low short circuit ratio) in PSCAD, can anyone help to find a suitable reference to develop that model.
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In order to obtain low Short Circuit Ratio, you can introduce significant value of impedance (preferably transmission line impedance) while connecting to Point of Common Coupling. Overall impedance value will be determined by the type of transmission line model you are using.
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In modified IEEE 30 bus system data active power loss is 5.660 MW under base load condition without using optimization. Please provide me data.
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for example, if I know current vs time curve for one single device; now I have one million device deliver current, each behaves independently, what theory or equation or simulation can I use to predict the million device behavior(overall current) along time?
regards,
tao
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Hi Tao,
I did not intend to convey a negative response; my response is a qualified maybe.
I doubt, given enough dedication, time and resources that anything is impossible; we Engineers have and will continue to accomplish the seemingly impossible because I think resolving the 'impossible' is part of any Engineer's job description.
There are other videos on YouTube where investigators have delivered the interim results of their ongoing research projects on applying Fractal and Chaos Mathematics to artificial Neural Networks, and (I humbly assume) to biological Neural Networks to illuminate the path towards the ultimate understanding of how the human brain actually functions.
Complex systems, such as an ant/bee/termite colony or Neural Networks have been discovered, through Fractal and Chaos Mathematics studies, to possess a collective property known as 'emergent behavior', in which whilst the individual insects or neurons by themselves may not seem to be very smart, as a group they are able to solve problems that are intractable using conventional analytical Mathematical tools based on linear algorithms. One classic case is the Travelling Salesman Problem, described by Dr. Robert Sapolsky of Stanford University.
In one of the YouTube links posted in a previous post, Dr. Sapolsky discusses how applying the complex system dynamics of a simulated ant colony, produces remarkably elegant emergent behavior, that very efficiently solves the Travelling Salesman Problem; a problem that has baffled Mathematicians and Computer Scientists for decades, prior to the application of Fractal and Chaos Mathematics, and the related field of cellular automata simulation.
I have a suspicion that using these approaches to the study of an electrical network with a million current sources, may yield some interesting results. I also suspect that in addition to using Fractal, Cellular Automata and Chaos Mathematics, the Monte Carlo method, suggested by Odair would be very valuable to approximate real world variations in the parameters of each current source, including the simulation of different fault conditions that would have an impact on the emergent behavior of the electrical network simulation.
The above paragraph may suggest this is a huge project; one discovery that may help to alleviate the challenges in constructing a simulation comes from experiments with natural complex systems; these systems will always bifurcate, i.e. they will always evolve along one of two paths; the path of evolution the complex system takes, depends on the initial conditions applied to the complex system. For electrical current sources, these initial conditions may be introduced through individual source variations in the wave mechanics (frequency, amplitude, phase), harmonics or impedance parameters.
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How to input variable wind velocity to the simulink model correspondingly to get the output for variable speed, using the lookup table in simulink is giving an error. I want to give wind speed measured for every 10mins and to dump/interface those in simulink model.
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Did you guys find a solution for that? I need to input variable wind speed to my simulink model.
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How can we sense the input current in bridgeless SEPIC converter in CCM mode for hardware implementation ?
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Thank You Sir...
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I build 3-phase 4-wire wind generator; At no-load it is rotating freely using hand,but when i apply a small load(app 10w 1-phase load) it is not rotating freely,it acquiring huge amount of energy so,is there any possiblity to isolate the load and alternator,or is there any chances to rotate freely.
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thanks sanjay,i will check it.
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I am using Silvaco Atlas to simulate a 3D solar structure. I want to pass current from one finger to another through the emitter and then measure the resultant voltage. Is it possible to model an edge shunt in this simulation? If so, what techniques are available?
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Dear Geoffrey,
Do mean by the edge shunt that you want to short one of the fingers to the anode of the solar cell. This can be accomplished in the simulation by the proper potentials on each finger and on the back electrode which is the anode. For example, you can put one finger on certain  positive potential and the other finger at zero voltage and the back electrode at zero voltage also. In this way you get an edge short. Then after that you calculate the current passing from the finger to the other finger through through the top emitter layer. It is easier to put a voltage and calculates a current.
wish you success
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I am implementing a microgid, and I need to connect a PV array along with a wind turbine, but since I am new on power systems, I am making a mistake in the model: PV array requires discrete powergui, Wind turbine requires phasor powergui, and I cannot have both powerguis in the same model. How is it possible to solve this problem?
I need a simple/easy answer since I am just a beginner in this area 
Thanks a lot
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Dear  Khadija Tazi   as per your problem i will suggest you to have a different software that will be suited best to you that is HOMER(Hybrid optimization model for energy resources ) . Be careful to data of wind & solar power plant . 
it will be an easy & best tool for you according to your problem 
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I am getting an error "initial conditions not valid" in DigSilent. I defined my own PID and first order exciter for a synchronous generator. When I run calculate initial conditions I am getting the above error. I am wondering how one can fix this. 
In have included the following initial conditions in the under Excitation system block diagram definition/Equations. 
inc(x) =  0 
inc(x1)= 0
inc(x2)= 0
-where x, x1 and x3 are state variables for the integrator, derivative and exciter blocks respectively. 
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Presume that your system is in steady state (steady state -> some signals are equal to zero). Then try to solve the equations of your transfer functions considering the input and outputsignals as variables. Your initial conditions should depend on these input or output variables (e.g. uerrs) . 
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I have already designed the LQR controller for DFIG system.
In LQR case
x_dot=Ax+Bu
y=Cx+Du
Here, I have already A, B, C and D matrices
In H-infinity case
x_dot=Ax+B1*w+B2*u
z=C1*x+D11*w+D12*u
y=C2*x+D21*w+D22*u
 How will I decide  the variables z and y?
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The choice of Z depends upon the designer which variable of the plant to be measured. 
The variable y is also to be decided by the designer, which state of the plat to be taken as feedback.
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For Voltage Drop and power loss calculations.Can it be modelled as 'T' or 'Pie'?
The Total Inductance of the Line is measured as 0.04H and Capacitance as 0.4 microFarad.
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for the very long transmission lines we use T model but for the normale lines length we use "Pi" model. (R,X and C)
for your question you must use "pi" model for this line to determine the voltage drop and power losses.
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Hi,
I need to prove the bidirectional power flow of EVs (V2G and G2V). What will be the control variables that need to be determined to do the same? I am working on the context of EV planning in smart distribution network.
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Any machines, induction or synchronous, connected to system(V), could work as motor(VE) or generator(EV), for synchronous machine when torque angle is positive(rotor field(axis) dragged the stator rotating field(axis) would work as generator, and motor when torque angle is negative (stator field drag the rotor field), and reactive power could be controlled by under excited(lagging), or over excited(leading) condition of machine. Induction machine, working as motor(VE) when slip,negative (rotor speed less than Ns)would take power at lagging power factor, and could be changed to run as generator(EV), with positive slip, by running rotor with higher speed than Ns, and would, supply power at leading power factor.
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if i have solve optimal power flow problem for following function
1. fuel cost
2. active power loss minimization
3. reactive power loss
4. voltage deviation minimization
5.Lmax improvement
how to find out where optimal location of DG-TCSC-SVC-UPFC-IPFC-STATCOM-DSTATCOM
and which case improvement when find its optimal location
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Dear sir,
The optimum location of STATCOM and FACTS is a problem you can solve using any optimization approach having in  mind the optimum function you need to solve.
The problem of the optimization of DG location and sizing in a distribution grid does not exist in practice. It is a waste of time to try to solve this problem. DG usually do not belong to the DSO or utilities and are connected according to the will of private owners of these assets and the availability of the primary energy resources existing locally.
This being said, if by any chance you happen to be facing an exception to this rule, then it is an outlier relative to the common and current practice.
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Hi,
So since apparent power S = |V|2 / |Z| does that imply that P + Q = V2 / Z for complex voltage and impedances?
The reason I ask is I'm trying to run a simple 4-bus NR analysis of bus voltages, however I'm not getting a converging result and I'm concerned that I'm not using the right function and Jacobian (using the aformentioned power equation above).
Since I have a 4x1 matrix for the compelx bus powers and a 4x4 maxtrix for the complex admittances ('Y_mat'), I was concidering the 4x1 voltage matrix the variable, and using the NR relation y = f(x), I took the power matrix as the constant 'y', 'x' as the 'volts' matrix and the functon was: volts^2*Y_mat
so the prime of the function is 2*volts*Y_mat.
Hence, the itterative NR equation is:
volts = last_guess + (power - volts^2*Y_mat)/ (2*volts*Y_mat)
But I think there is a flaw, I'll attach the code if anyone could please take a look. I've tried all mannor of things such as conjugates, abosolutes and negatives, with no success.
I'm not confident in the prime of the function being correct, or using this power equation.
Thanks!
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I have made generalized MATLAB program using N-R method for load flow study.
Tell me clearly what do you want? my e-mail is: mgrabbani@easternuni.edu.bd
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Hi
I am working on load frequency control,I want to determine a single machine equivalent model of real power system(Governer -Turbine-Generator) by transfert function. PLZ provide best suggestion to solve this problem
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Given very clearly in Elgerd's book on energy systems
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I have an issue with the simulation of a PV system. I'm using simulink for the PV panel, the buck converter and the algorithm (inside a matlab function block).
I had to use discrete simulation as i was having problems with continuous mode. I got the best results with control sample time of 10us and power sample time of 0.1us but i've been told this control velocity is really fast and that it requires a powerful processor. 
I don't have a lot of knowledge of field implementation so i would like to know if indeed this is too fast or what other options i might have,
Thanks in advance
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It depends on what is a "powerful" processor for you, and what is the amount of processing to be done between each sample.
10us is a 100kHz sample rate, should be easily handled by low-end uC that run above 10MHz.
But 100ns is a 10MHz samplerate, this one is the culprit, and the answer will depend on many factors:
   - acquisition / treatment: sample after sample, or by chunck
   - type of underlaying OS, a full featured linux can be "bloated" for such application, while a lightweight scheduler like FreeRTOS will just fit the bill...
   - DMA
   - ...
If you're targeting "low-end" CPU, you really should implement the process without floating point (fixed point or integer arithmetic are the ways to go). So another option is to do the "number crunching" on a FPGA.
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design battery model but want to optimize the results using optimization techniques.
plz suggest how to solve it.
how to model capacity model on simulink.
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Dear Mahendra
you can look at the Matlab Simulink model described in this link
Gerro
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I am designing a dc- dc high power converter with fixed input voltage and I want to know, what are the factors which decides the amount of current drawn from the source by a dc-dc converter ? , how can I improve the current drawn from the source so that maximum energy could be transferred through the the power converter?
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If your DC-DC converter is output current stable, the main factors are output power, output current and the corresponding topology; if your DC-DC converter is output voltage stable, the main factors should be output power, output voltage and corresponding topology.
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Generators are rated power from 3-50 MW. In attachment is one test diagram for 5 MW generator
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Dear Gabriel. Thank you
That is it. I have found answers on Fig 11 in the first and Fig 12 in the second paper which confirm our measurements for 5 MW steam generator which time was 40 min.
Srete
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Hello, everyone I'm working on optimization of coordinating overcurrent relay I wrote allocation codes and optimization code in matlab but I need to recall mfiles in PSCAD. I want o know is that possible to link between matlab and pscad wich I able to use matlab codes in Pscad?
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Hi ,
i have this problem too!if you find your answer , please help me.
thanks alot