Science topics: Power Systems Modelling

Science topic

# Power Systems Modelling - Science topic

Simulation of Power Systems as a whole and of each separate component

Questions related to Power Systems Modelling

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!

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

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

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.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!

Is there any code / package / script to automatically generate single-line diagrams from PYPOWER/MATPOWER casefile or IEEE CDF formats?

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

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?

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!

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

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

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)

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.

I need a research based Article On Power Systems which has been modelled on any non Linear Technique such as Back Stepping etc.

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

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?

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

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

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.

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

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?

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

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!

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?

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

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

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

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?

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

where and how to get the IMPACT (IGBT Model Parameter extrACTion) software pack?

Out of several DC-DC converters available, i wish to know which converter will be maximum efficiency

I have to start researching about "Integration of Off-Shore Wind Energy Conversion Systems" but I am confused what parameters to research for?

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

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.

How ca n I draw a curved of receiving-end voltage magnitude as a function of load?

10-2- Please see the attached files.

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.

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 )**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

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.

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.

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!

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?

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?

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

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.

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?

Dose sampling frequency of 100 kHz achievable in pratical engineering?

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

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!

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?

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

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.

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.

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

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.

How can we sense the input current in bridgeless SEPIC converter in CCM mode for hardware implementation ?

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.

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?

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

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.

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?

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.

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.

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

Hi,

So since apparent power S = |V|

^{2}/ |Z| does that imply that P + Q = V^{2}/ 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_matso 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!

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

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

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.

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?

Generators are rated power from 3-50 MW. In attachment is one test diagram for 5 MW generator

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?