Science topic

# Electrical Power Engineering - Science topic

Electrical Power Engineering is an infrastructure of bulk electrical energy transfer.

Questions related to Electrical Power Engineering

It is a network of 30 earth pits. 3 sets of10 pits.

I have disconnected all the 3 sets. However, when I check for the resistance between the network of first 10 and that of the second set, I get 45ohms. Should it not show in k or M ohms as they are not galvanically coupled. One thing is for sure that they are not shorted as the resistance is as high as 40+

If I disconnected one pit from the remaining 9 in the first set, I get around 250ohms with multimeter.

I am trying to decouple all the 3 sets from each other but to no avail.

is it due to the high conductive compound that has gone into these pits?

Meanwhile, I'll try to explore more on this

Voltage collapse in power systems

Is it just in order to eliminate the circulating currents among DGs by maintaining same voltage and angle ? Also how does it improve the stability of the system?

Which research area in Power Electronics will make for a good Master thesis in the field of Power Electronics? Would be obliged if someone can inform me about the ongoing scope of such research projects. I am searching for a good research proposal for my Master thesis in the domain of Power Electronics.

Would be obliged, for your help.

Regards

I am simulating a power converter circuit on Simulink platform. This also include a 400 V AC grid. I am not sure about a generic thumb rule to define the impedance of the cables for this 3ph 400V Grid system. Any suggestions?

Normally, for a forward fault, phase difference between voltage and current of relay (theta) lies between -90 and +90; and for a reverse fault, theta is outside of this range. Some works, however, use negative components of voltage and current of relay to identify fault direction. I want to know that what is the criterion for a forward/reverse fault in this condition? In my simulation studies, phase difference between negative components of voltage and current lies between -90 and +90 for a reverse fault.

When I study about inductors I found that inductors have a constant value and value of inductance depends upon the permeability of core. And when I see the hysteresis curve then found that permeability depends on magnetising current and initial state of core(if it has retained some magnetism earlier). So I think inductor is non-linear in pure sense but approximated to linear. And in capacitors also due to analogous nature we can predict that it also nonlinear and capacitance is also not fixed due to variable permittivity.

Hi,

I am working on tracing current unbalance in HV systems. All papers study unbalance based on simulations which may fail in practical conditions. I'd like to know whether there is any standard for CT/CVT accuracy class used for current/voltage unbalance measurement or not. I have read IEC60044-1 and IEC60044-5 for CT/CVT standards. There is also IEC 61000-4-30 which defines unbalance measurement classes and it is indicated that CT/CVT accuracy may affect measured current/voltage unbalance ratio in practice (which is obviously correct), but no numerical analysis is provided and here my problem arises. Let's say maximum accepted voltage unbalance in HV systems is 1%. A low-accuracy CVT (say 3% class) may cause a voltage unbalance of <1% be measured >1%. In other words a BALANCE system look UNBALANCE or vice versa. Is there any standard that provide unbalance limit + measurement instrument's accuracy class?

Something like:

If you are using a CVT of 3% accuracy class, maximum acceptable voltage unbalance is 2%.

If you are using a CVT of 1% accuracy class, maximum acceptable voltage unbalance is 1%.

(I know IEC61000-3-13 is another standard related to unbalance, but unfortunately I don't have access to it)

Regards

Respected Prof. Dr. XXXXXXX;

I hope you are doing well and are in good health.
My name is Engr. Muhammad Muneeb. I am currently studying in 7th-semester and doing BSc Electrical Power Engineering from The Islamia University of Bahawalpur, Pakistan. I am maintaining a 2nd position in the session with a CGPA of 3.80/4.
My 7th semester will be completed at the end of Jan 2021 and my 8th semester by the end of June or mid of July 2021.
During my undergraduate, I have worked on semester projects to actualize and implement the theoretical knowledge of Control systems, Power Electronics, Electronic Devices & circuits, High Voltage, AC & DC machines, and also Signal processing and digital signal into practical work.
I have worked on mini (semester) projects like Digital Thermometer using Arduino, Obstacle avoiding Robot using Ultrasonic sensor and currently working on Single-phase Smart Grid Tie Inverter as my Final Year Project. I am also doing research and will publish a paper with one of my department teachers; who is doing a Ph.D. in Electrical Power Engineering.
I just saw a Post XXXXXX on the Facebook group regarding a research position for the Master's Program in Machine learning and robotics-related field at XXXXXX University. I have also read about your projects and achievements. I am very enthusiastic to conduct research and pursue MS under your supervision.
I have attached my Cv and transcript (currently only 5th semester available) with this email and looking forward to hearing from you soon. Also if you need anything else from me please ask me as well.
I shall be thankful for your response.
Sincerely,
Muhammad Muneeb
Whatsapp : +923030788740
WeChat: +923357915880
Skype: muneeb.mazhar1

Is there a real dataset (meansurements) that recorded the daily values of load profiles (Residential, Commercial and Industrial Consumers)?
I am trying to test an algoirthm in machine learning that will cluster the different loads automatically. But for that I need a dataset as input.

I have dataset which shows the length of power lines. I need to classify the lines based on the line length. Is there a rule to classify the High voltage (HV) and low voltage (LV) lines based on line length? For instance, can we say lines below 500m (meters) are considered as LV lines and lines above this length are HV lines?

Dear researchers,

I have the following questions:

1. I want to know how I can read a number of TABLES and PARAMETERS from excel?

2. How can I make GAMS show the zero values as "0" in the results? Obviously, the program drops them...

I know how to convert one table or parameter from GAMS to excel. When I use 'xls2gms' or 'gdxxrw', it is ok but just for one table, for example.

However, in my case study, there is a sheet that contains many tables, and I don't know how to convert them to the assigned table names in GAMS. The ide shows an error with this regard!

Thanks for your help in advance.

I use a piezoelectric sensor, a humidifier electronic circuit and a 32-volt power supply to generate high-frequency ultrasound waves. I use these waves to atomize the liquid.

the problem is that the viscosity of the liquid is high, so the generated ultrasonic waves cannot atomize the liquid well.

any idea for this problem?

for example, can i use two circuit with two supply power and connect their output to the sensor to higher the sensor power? or ...

I'd like to know the common FACT devices in distribution systems.

I want to simulate nonlinear state space equations, I need it for stability analysis.

Hello,

I am comparing different techniques (Current Injection (Already calculated), Newton Raphson (Already Done), and Backward-Forward Sweep (facing problem)) for load flow analysis for three phase unbalanced system though Matlab.

From couple of weeks, I have tried to develop matlab code for Backward-Forward sweep but failed. It will be great help if I get code (even general/conventional method will be very helpful for me) for backward-forward sweep for three-phase (not single phase).

Looking forward for your help. Thanx.

Cheers,

Muhammad

I need ETAP software. Can anyone please share the link? As I am new user of ETAP, I also need a user guide please.

I am interested to simulate distribution networks with distributed generation utilizing custom controls. Simulink is quite versatile in control system design and is friendly for people preferring visual approach to programming. But I am not always satisfied with how it solves power flow for detailed network models.

Lets say that I am looking for more reliable power flow solvers, but with control system design versatility of Simulink (preferably with visual programming). Any suggestions?

How to measure power factor in a single phase connection?

I am designing a control for bi-directional LLC-SRC DC-DC converter. The converter charges a battery from the grid. But during reverse operation, i.e when the current flows from battery towards the grid, what may be the impacts of current on the resonant capacitor (Cs as attached)? Do I need to wait for the discharge of DC link capacitors (fast/slow anyhow) on both sides? I cannot see any abnormal change or fluctuations during simulations. For practical approach, I am not sure. Any suggestions?

I am currently designing a BMS for a 48 V Battery pack of an electric vehicle. One of the major challenges regarding the BMS is to equalize the voltages of the cells (as different cell have different ageing) of the battery pack. How can one address this issue??

As we have seen that most powerful and expensive quadcopters being swept away by prevailing wind gusts and losing connection with the controller, and even that “fail-safe” GPS-enabled Return To Home feature will struggle and oftentimes fail when flying into a strong headwind.

How to make it reliable and robust for sever weather conditions?

I want to use multiple DSTATCOM in my project,thus it's price is very important to be minimum.This device is the same with single phase inverter, but it injects reactive current only to the connected node in parallel to the 1-phase load.could anyone please inform me./thanks/

Is it possible to estimate eletrical load based on statistics and geographic population?

I want to estimates load profiles of houses based on available statitics like total population, avergae energy consumption per year by that area, average persons livining per house, size of building etc.

Is there way a way to estimate load based on these statistics? some of the availble statistics are attached.

I am trying to estimate load profile for different houses based on occupancy profiles, number of people, total rooms, and age factor. Is there a way to estimate energy consumption based on the data of these parameters? Any ideas would be highly appreciated.

Resistances in transmission system are negligible, so 1.0pu voltage assumption holds. However, in distribution system, resistances are not negligible. Please provide information about some simple ACOPF relaxation method. Thanks.

Consider a sinusoidal supply at fundamental frequency as shown, with a series inductive reactance leading to a bus. Let a diode rectifier load be connected to the bus. The switch Sw for resistive load be open. In this condition, the diode rectifier draws fundamental current from the source and also sends back harmonic current to it. Thus, the voltage drop in series reactance is distorted by the harmonic and so bus voltage is also correspondingly distorted. Now if switch Sw is closed, the resistive load draws both fundamental current as well as harmonic current from the distorted bus voltage. Both current components will lead to power dissipation in resistance as bus voltage contains both the corresponding voltage components. The question is from where is the harmonic power supplied to the resistor ? The sinusoidal source by basic understanding, cannot deliver any power corresponding to harmonic currents as its voltage remains sinusoidal, even though its current contains harmonics.

As a part of Industry 4.0, IoT also enjoys a vital position in smart technologies. However, with respect to power electronics, I have read that privacy over the internet could be a concern. Does this technology benefit us in power electronics /power systems domain? Are there any applications available?

How to integrate the harmonic power flow with the power flow in MATPOWER?

Are there any standards regarding islanded micro grids applicable in terms of general operation, especially regarding AC/DC converters with battery, PV or other sources.

How can I solve this PV modeling equation: I=Iph-Io*(exp((V+Rs*I)/Vt*n)-1)-((V+Rs*I)/Rp), knowing that all the parameters are known except I and V? I'm trying to develop a circuit PV model to simulate a real PV module from the datasheet parameters. Thank you

The increase in the trend of distributed generation has led to the formation of community microgrids. What is the best possible solution to connect single-phase loads to a microgrid with 2 level voltage source converter?

I feel one possible solution to connect single-phase loads is to use a 3-phase 4 -wire transformer.

For example, if I want to find the stochastic OPF of a system, shift factors can provide a way to find shifted power for different scenarios. Therefore, OPF for each scenario is not required but only for base case. This will reduce simulation time. Please share relevant code if possible. Thanks.

Hello everyone,

I have three questions about connecting onshore wind farms to substations:

1) I know, that larger onshore wind farms are connected to higher voltage levels (110 kV or 132 kV). But which voltage level would I choose, if I only have one wind turbine? does a rule of thumb exist depending of the wind turbine / farms capacity (MW)? A reference to cite would also be nice.

2) I have a wind farm which is already connected to a substation. Another wind farm is newly built and is nearer to the first wind farm than to the substation. Is it also possible to connect the wind farms, instead of the connecting line to the substation?

3) Do you have references for costs to connect wind farms to substations for UK? For example costs per km.

Thank you very much!

Jann

I need to design a 11Kv distribution line for a rural area. which software will be good for this purpose

I am studying the effects of FACTS devices on power oscillations in a system.For this purpose I have used an IEEE 9 bus system and created a three phase fault on bus 5.The UPFC should provide damping to clear the fault and hence decrease the fault clearing time.But I am not getting the usual results. The load angle versus time curves are attached. Can someone help me to figure out where I am going wrong?

I have done a theoretical analysis to find out the rating power that need to be produced from PV panels depends on the datasheet given below at 7222W.

I have calculated the sizing design of PV arrays for 4 panels connected in series and 7 in parallel to get total at 28 panels at rate 120V and 60A that need to meet the demand.

Note Xsys=0.09 ohm at 25KA current fault level from IET datasheet.

the issue is how to implement this demand of power from the PV using matalb codes or simulink by demonstrates parallel and series connection of solar panels to get the rate at 120V and 60A?

the attached files shows schmatic of proposed system

Regards

when temprature ar radiation change , value of series , shunt rsistance change also

Hi everyone,

It's known that the cutting process of electrical steel introduce additional iron loss. Research articles indicate that the increase of iron loss when steel is cut with CO2 laser is much higher than the case where the steel is cut by punching. I was wondering, if the trend is the same for Nd:YAG laser cutting ?

Kindly, provide some references for the same.

Through Simulink 'Powergui FFT Analysis Tool', we can directly obtain the plots of different harmonics in Bar or List display style. However, I am looking for ways to plot these harmonic contents with respect to time and to show their decaying nature during transformer energization (as stated in the literature).

I've simulated a simple three-phase four-wire distribution system and I've use a DSTATCOM for load compensation. Its control algorithm is based on the PQ theory. I have a problem in compensator block. When I run my simulation, a error appears. Can anybody ti help me?

Here,I've attached my simulation and PDF files,Please check it.

I want to inquire about any advantage or disadvantage of using boundary power over boundary bus angles when two areas coordinating

I have a hard form of the book with me. I am looking to have a .pdf version of it. Please share any link where I can have it.

Thank you

Suppose we have capacitors in the line towards the load end to compensate for lagging Kvar...At night time some of the load might be switched off leading to a leading power factor condition in the circuit....Can anyone tell me some ways to work out a circuit in which I can bring v and i in phase when the loads are suddenly switched off and prevent leading pf condition?This has to be at minimum cost...

Here is the formula for 3L and LG fault :

I= Vf/(Z1) I=3Vf/(Z0+Z1+Z2)

By analyzing the formula, one can come to conclusion that LG fault is more severe (assuming Z0<Z1=Z2, which is the usual case). But are we forgetting the fact that in 3L fault, there is a major role played by sub-transient reactance (Zst) which is much smaller that Z1. So the formula gets modified to I=Vf/(Zst) for LLL fault (applicable for first 2 3 cycles). But I have no clue whether same phenomenon occurs in LG fault as well or not and I am similarly confused with this. Can anyone help?

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)

For my new design of Hydroelectric system that can be built and operates efficiently and reliably in oceans and seas.

Normally, multi area in power system means areas are at same voltage level. But my opinion is that TSO DSO coordination also come under umbrella of multi area. Please correct me if i am wrong.

As we know that any MILP/MINLP problem is feasible only on some points in its search space. Consequently, it is not possible get its JACOBIAN as well as HESSIAN matrices, as I think. As a result, for MILP/MINLP problems it is not important to know its convexity. Further, as MILP/MINLP problems are having their feasible search space in form of a set of some discrete points so these problems are NON-CONVEX.

How can you justify my observations? Am I right? or Am I missing something very important?

You comments about the above observations are highly appreciable.

With sincere regards,

M. N. Alam

What is the most important topic to work on now a days on electrical network? Energy storage system, distributed system (Microgrid) operation and control, or Demand response of an electrical grid ?

For energy storage -- name some modern storage system other than battery storage.

Demand response -- ways to predict the demand (probability).

Grid operation and control-- design strategy (appropriate circuit and challenges)

What is the function of line traps other than communication?

High-penetration of renewable power generation throughout the network might increase transmission/distribution congestion. What are the effective tools in both transmission and distribution level for managing congestion due to renewable penetration?

The estimated angle (x_est) in linear(DC) State Estimation using WLS criteria is calucted as follows:

x_est= [ Inverse {Transpose (H) * W * H } *Transpose (H) * W ] * z

Here z= Matrix Real Power Injections into the buses

W = diagonal matrix

**Question:**How to extract

**H**matrixusing matpower

I need some help to calculate a fault distance in a H.V transmission line. I used a simulink(Matlab) model with a programing code for a simple transmission line with 2 sources.

The result simulation gives me an error in fault distance value. I can send a code and the model. Please some helps.

Thank you for consideration.

We would like to buy a new Battery Test Station (Battery Cycler) for testing 150Ah LFP Batteries in Crate (0.1-2C). Apart from the Max Voltage and Current range of the test system, what else has to be considered while buying a test system?

It would be very helpful if anyone can suggest some good test systems suppliers for this test (>300A)?

I'm working on "

**Proper Placement of DG(Renewable Resources) and Reliable Protection Scheme for Power System**"I need help in placement of Inductor in Power system to minimize the Fault Circuit current, without DG and with DG.

I have attached Simulink Model bellow.

I want to do switching overvoltage simulation in power system. What are the recommended practices to do the job? Can we do it without any commercial software (e.g build own algorithm in Python)? Thank you in advance.

Say we got a solar array which supply power to battery through a DCDC converter. We want to design two control loops for the converter.

One is the inner(fast) loop which regulates the converter output voltage or current. This loop can be analysis by the traditional converter small signal model.

Another one is outter(slow) loop which is regulate the converter input voltage or current (solar array output voltage or current). How can we analysis the stability for this loop? Do we need to include the small signal module of solar array? If the voltage or current is regulated by some algorithms, how to model the algorithm?

Any tips would be very helpful, thank you

F. Blaabjerg, ph.d. Professor (Full), Aalborg University, Aalborg · Department of Energy Technology.

This parameter is used for recognition of islanded networks.

Dear All,

I am currently working on thesis on Reduced switch count inverter for driving three phase BLDC motor. However I am not clear abut how to calculate the DC link capacitor values so that it works good with load(impedance).

I understand that there is a relationship between the Capacitor reactance (Xc) and the impedance(Xl) reactance that is feeding the DC capacitors mid point. Suppose if I know the impedance, rated speed, DC voltage How d I get the Capaciotrs value?

What abut the Capacitor value calculation when the DC link mid point in unbalanced?

I would be really thankful if anyone of you could guide me or help me through this.

Regards,

SM

Dear All

Can you provide me with maximum allowable currents of branches in IEEE 33 bus distribution system?

Thank you

Ahmad

OpenDSS is a wonderful package, but it is not suitable for simulating some special features of railway traction network, it would be fantastic to have something similar related to Railway power systems. What do you think?

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.

When we use less surface area of solar chimney with using a geothermal process - what is the efficency and what is effect of the project?

Why do we use clock circuit when we are designing certain micro controller onto PCB? What it is usage?

What other circuits do we need in order to proceed?

Would you be able to give some advice when you are start from the beginning designing the whole PCB boards?

Does magnetic field can heat the human body?

According to the International Commission on Non-Ionizing Radiation protection (ICNIRP), there is a maximum allowable magnetic field exposure to our body. I don't understand why magnetic field can be harmful to our body. I understand that electric field can heat our body by ionic polarization and dipole rotation of an atom or molecules. Whereas, magnetic field can only heat magnetic materials.

Hello,

I have a question on PWM Technique for Power Electronics Inverter.

For 3-level inverter and sine PWM, modulation index is evaluated by

m=(V(line-lineRMS)/sqrt(3))*sqrt(2))/(Vdc/2)

Now, when I change the technique to Third Harmonic Injection PWM (THIPWM), the DC bus utilization increased by 15.5% which is evident.

Can anyone tell, how the equation to find modulation index will change in THIPWM? How one can calculate analytically the modulation index in THIPWM technique?

as a simple logic, for THIPWM, I reduce modulation index by 15.5% of value which I obtained for SPWM. I am not sure is it the engineering way or not.

Regards

Aalok

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?

Practically, in electric power systems (macrogrids or microgrids), the scheduling of generation resources is done on day-ahead or hour-ahead basis? Can you elaborate this issue? when the balancing is done? how non-dispatchable generating units such as wind and power take part in the scheduling?

Thank you

Regards,

Ahmad

I have a working model of a healthy 3-phase induction machine based on Krause's model, but need help to model stator and rotor faults to analyse the current spectrum. Any help would be very much appreciated. Thank you.