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Questions tagged [power-grid]

Refers to grids or networks that deliver electrical power on a large scale, that is, networks for bulk power transmission. For smaller scale networks, refer to distribution-network or microgrids.

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What frequency do long-distance undersea powerlines run at?

I recently saw this photo of the project "NATO-L", or North Atlantic Transmission One-Link. It's an under-sea powerline planned to connect Europe with North America. Does anyone know what ...
spinjector's user avatar
1 vote
1 answer
53 views

Do we need MPPT in grid synchronization and string inverters? [closed]

I have two questions regarding the MPPT grid synchronization. I have seen that it takes a few minutes for the inverter to get synchronized with the grid. I want to ask that does the inverter first ...
kam1212's user avatar
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3 answers
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How to offset a sinusoidal voltage centered at 0 V for power grid measurements

I am trying to take voltage and current measurements from the power grid (120V 60Hz) and process them with a 3.3V based digital signal processing board (TI F280049C launchpad) I am using LV25-P and ...
Larcron's user avatar
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2 answers
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How does a hydroturbine induction generator control its own frequency/water flow if it is already excited/pre-determined by the grid?

I was reading this article How do you connect hydro to the grid? and the author states there are two methods. One by a fixed-speed induction generator and another by a grid-tied inverter. I understand ...
t-osu's user avatar
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1 answer
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Terminology: Proper way to denote typical European 3-phase AC grid

The widely known 3-phase grid in Europe with 50 Hz and 400 V between two phases and 230 V between each phase and neutral is often referred to as "3 x 400 V" or "3 x 230 V". Is one ...
Dave's user avatar
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0 answers
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How is TN-CS safer than TN-C

Why not just run two PEN wires? Can you explain a situation in which having wires with separate and designated PE, N functions is safer than having two PEN wires? Or is that basically where all of the ...
arctiq's user avatar
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19 votes
5 answers
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Why does grid voltage drop at 10pm?

The premise of the question may be the problem so please let me explain first. In my home at night we have a bunch of nightlights and we run a small fan in each bedroom for the noise and/or cooling. ...
Aldus Bumblebore's user avatar
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1 answer
183 views

Why do inductors and capacitors cause phase shifts between current and voltage? [closed]

I am learning about grid level stabilization services. My native language is German and I am translating the specific terminology. If I use the English terms incorrectly please edit my below sentences....
Merlin Nestler's user avatar
5 votes
2 answers
2k views

Why did I still have power after a tree cut the neutral wire leading to the transformer?

During a storm, a large branch landed on the drop line to my house. This snapped the bare neutral cable cleanly in two but the two hot legs remained intact. I had no idea this had happened until I ...
kpg's user avatar
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Why is Voltage Drop Across the Inductors of an LLCL Filter a Concern for Grid-Tied Inverters?

I'm working with a single-phase grid-tied inverter that utilizes an LLCL filter to interface with the grid. I've come across design constraints that mention maintaining the voltage drop across the ...
Alawi Midher's user avatar
1 vote
2 answers
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What information can be discerned about street-side power transformers just by looking at them?

I am new, and delighted, to be part of this stack. I was just wondering from the two images of power transformers shown below what specifications can be gleaned from their outward appearance alone? ...
Albert F D's user avatar
10 votes
4 answers
1k views

How can overproduction of electric power be a problem to the grid? [closed]

Recently, in Brazil, we had a major shutdown of the electrical grid of the entire country (wich is mostly interconnected across the majority of the states). After official investigation, the culprit ...
Sieg Novak's user avatar
1 vote
1 answer
116 views

Simple transient simulation model for synchronous generators

I am writing a simple transient circuit simulator as a personal hobby/experiment. My ultimate goal is to develop a simple 2D game for teaching/learning concepts of power systems in an intuitive way. I ...
Cyclone's user avatar
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3 votes
2 answers
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Why don't we use the third harmonic in power transmission?

For some high power high voltage lines DC is used with the advantage that sinus wave AC obviously doesn't use the line to it's maximum capacity at all times. To correct this, we could use square wave ...
Čäřý's user avatar
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1 answer
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Effects of Solar Distributed Generators on Utility Grid

The figure Below is a test block diagram that I would like to model and simulate in DigSILENT PowerFactory Software to analyze the effects of SDGs on the utility grid’s Power losses, Voltage ...
Ronny Alfons's user avatar
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1 answer
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Dual-Power Sourcing for 15MW Electrolyser: Wind Farm and Electrical Grid Feasibility [closed]

I am part of a team working on a 15MW electrolyser project comprising six 2.5MW containerized electrolysers. This setup will be positioned near a 20MW wind farm, and there is also the potential for us ...
Ricardo's user avatar
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2 answers
855 views

Why is there loss of power between solar inverter and utility meter?

I have an on-grid 10 kW system installed with two-way recording meter. Recently I have noticed that units generated as shown by inverter are more than the units recorded by utility meter. Previously, ...
Fawad Pasha's user avatar
12 votes
3 answers
1k views

What are these circular basket-like structures on a high voltage transformer's insulators?

Wikimedia commons contains this public-domain image of a high-voltage transformer of the Tarza power plant in Iraq, taken by Marvin Daniels in the U.S. Army: There is much I do not immediately ...
Landak's user avatar
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1 answer
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Where can I find synchronous machine datasheet?

In the laboratory where I work, we have developed our own MATLAB library for simulating transient response of power systems, and I am currently working on some simulations of IEEE 9 bus system. I was ...
Vitor Uekawa's user avatar
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0 answers
106 views

Conversion from DQ0 to dq0 and vice-versa

I have been working with multi-machine power systems, and I have been struggling with the transformation between the dq0 and DQ0 frames. I will first introduce my understanding of these frames, and ...
Vitor Uekawa's user avatar
33 votes
7 answers
22k views

How to ramp up a factory consuming a lot of energy?

Can you please explain how to manage the process of ramping up a factory with a big electric consumption? I am wondering how it is possible to balance the grid during the start up phase of a big power ...
Merlin Nestler's user avatar
9 votes
1 answer
327 views

What does this odd-looking contraption on the back of an electrical power utility pickup truck do? [closed]

Spotted on a Con Ed truck driving around Brooklyn, NY streets late at night. Some kind of EM field sensor maybe?
bigjosh's user avatar
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2 votes
1 answer
71 views

Bonded ground, other line reading is 0 volts

Can someone explain this data to me: All machines connected to the grid are normal. Line 1 to line 2 = 230 volts Line 2 to line 3 = 230 volts Line 3 to line 1 = 230 volts Line 1 to ground = 230 ...
Benjamin Bacarro's user avatar
6 votes
2 answers
886 views

What is this device on an electrical pole?

I see this setup all over my neighborhood and am curious about one of the components. The houses on the outer edge of the neighborhood seem to get their electricity by tapping into one of the phases ...
amazonprime's user avatar
14 votes
1 answer
2k views

Are these transformers or giant capacitors?

I sometimes see these devices along power lines when I'm driving and was wondering what they were. They look just like the regular transformers that I see on top of electrical poles, but it seemed ...
amazonprime's user avatar
2 votes
2 answers
552 views

What is the relationship between a power line's voltage and the amount of power it can transmit?

I am considering a classic power distribution network using 3-phase AC power. There is usually power lines of various voltages ranging from 10kV to 400kV. These values change country-by-country. For ...
Bregalad's user avatar
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2 votes
0 answers
113 views

Is an EMP weapon a real threat to power grids?

I do not see how an EMP is realizable. The idea is a nuclear bomb detonated high enough will release a strong enough EMP to take out a country's power grid without damaging infrastructure. In my ...
Blake Borskey's user avatar
1 vote
2 answers
250 views

How does a power generator control its output to the grid?

I found this answer: On-grid solar system - how to control power out from solar system to grid? But I would like to know a little more about the details and the dynamics of the inverter. As an example,...
BenG's user avatar
  • 115
2 votes
1 answer
146 views

Can a generator in an electrical grid be destroyed by disconnecting the power at a distant substation

I've read that if the length of a transmission line is a quarter wavelength then an open circuit at the sink would appear as a short at the source. Consider a real electrical power transmission line ...
Dazzleboo's user avatar
2 votes
4 answers
2k views

How can earth be connected to neutral?

I recently installed a solar inverter in my house and learned that earth must be connected to neutral. I am very puzzled by this, since AC changes direction of current flow, so according to me, there ...
Philip's user avatar
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1 vote
1 answer
193 views

Is it possible to have a current higher than the transformer short circuit one?

I am a student and I want to understand the following aspect. I know that protections and whatever devices installed in the grid must tolerate a current higher than the short circuit current. At the ...
Samuele Benito Di Gioia's user avatar
2 votes
1 answer
488 views

How do grid tie inverters sense the mains phase and quality and at the same time feed current into it?

Grid-tie inverters synchronize the phase and also check the quality (frequency, magnitude) and shutdown in case of errors to prevent what's called islanding, i.e. to prevent feeding current to network ...
Juha Mattila's user avatar
1 vote
1 answer
139 views

Power grid dynamics: Does increased power use = increased fossil fuel use in grid?

Say I come home on a hot day and crank my AC full blast (colder.) The grid is powered by wind, solar, hydro, coal, and natural gas. The additional power required by my cranking up the AC cannot be ...
Ray J's user avatar
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2 votes
2 answers
528 views

How does lightning increase the voltage within a substation (how does current increase voltage)?

I'm new within the power industry and was introduced to a scenario I had a question about. So, while discussing the need for surge arresters came up, we began talking about lightning. I know that ...
Justin Montego's user avatar
6 votes
2 answers
247 views

How do power grid operators regulate the power flowing through their networks?

My question: How do grid and transmission line operators regulate the amount of power flowing in their networks, both to utilize the network optimally and to enact delivery policies like those in the ...
mkay's user avatar
  • 169
21 votes
4 answers
3k views

How do large electrical grids stay in phase?

I am a math student with some background in physics so apologies if the question is naive - but I'm trying to understand how large electrical grids like the Eastern Interconnection maintain locally a ...
Dominic Wynter's user avatar
0 votes
1 answer
353 views

Grid Voltage Ride Through using PSSE

I am trying to simulate a low voltage ride through (LVRT) lagging case (Qgenerator = max). The inverter seems to be going to momentary cessation, and although the output power at the inverter ...
juliensadaka's user avatar
0 votes
0 answers
63 views

What happens if there is a reactive power imbalance in a large grid?

Consider the Continental Europe power grid. Supposing there is a 1 GW of active power imbalance in the grid. This would lead to a frequency drop/rise in the whole grid at steady-state. What happens ...
Samuele Benito Di Gioia's user avatar
13 votes
2 answers
2k views

What is the reason for these utility poles with a 6-sided hole in the middle for conductors

What would be the technical (Electrical, structural, safety) reasons for a utility pole like those shown below? This picture was taken in Arkansas and is what I assume to be 3-phase power. Note how in ...
Austin Downey's user avatar
0 votes
1 answer
66 views

What happens on a DC-DC grid connection after a perturbation in the synchronous grid?

Consider the Continental Europe synchronous grid. This power system has some DC-DC connections with other countries (for example one with Great-Britain). Suppose now there is a sudden big outage ...
Samuele Benito Di Gioia's user avatar
-1 votes
1 answer
57 views

Do static generators maintain a constant voltage at the terminals?

Do static generators maintain the terminal voltage constant like a synchronous generator does? If not, are they at constant current? With static generator I mean photovoltaic systems connected to the ...
Samuele Benito Di Gioia's user avatar
0 votes
1 answer
67 views

How to get a static generator starting from a synchronous one?

I want to model a static generator (a photovoltaic one) inside a simulation tool. This simulation tool has no static generator (it is quite new and not user friendly). My idea was to model a ...
Samuele Benito Di Gioia's user avatar
1 vote
1 answer
140 views

Is the reference voltage for voltage control the RMS between the three phase voltages?

Suppose to provide voltage control with an AVR connected to a synchronous generator. A voltage reference is compared with the output terminal voltage of the generator, and the error between them is ...
Samuele Benito Di Gioia's user avatar
1 vote
1 answer
76 views

Is the same overcurrent relay used for both phase-to-phase faults and 3-phase faults?

In MV grid with no distributed generators, 50-51 overcurrent relays are used to detect both phase to phase faults anf 3-phase faults. In Italy, time independent characteristics are used inside these ...
Samuele Benito Di Gioia's user avatar
0 votes
0 answers
124 views

Reactive power fluctuation

We have 6 Caterpillar gas generators 3520c. One of them when synches with the grid. Its kVAR fluctuates over wide range and the aux voltage too and the excitation volt and current. We checked AVR and ...
ahmed mady's user avatar
0 votes
1 answer
75 views

Transformer ratio of a transformer that connects a generator to a MV grid?

Inside my one-line diagram in which I am studying some properties of the medium voltage grid, I want to connect a generator to the MV busbar to study the hosting capacity. Therefore there is not a ...
Samuele Benito Di Gioia's user avatar
0 votes
1 answer
58 views

Admittance matrix when switch is open

In the following there is an example of an admittance matrix. https://en.m.wikipedia.org/wiki/Nodal_admittance_matrix If y13 had a switch and it is open, what happens to the admittance matrix? Thanks
Tims's user avatar
  • 111
1 vote
1 answer
239 views

Fault impedance type?

Usually fault impedances are resistive type. But is it possible to have a mix of resistive and reactive component in fault impedances? Looking at many simulation tools, they give the possibility to ...
Samuele Benito Di Gioia's user avatar
1 vote
1 answer
305 views

Does a grid-connected induction generator create phase difference between the grid voltage and generated current?

I saw an answer to another question that stated: "An ordinary induction generator connected to a power grid will draw lagging reactive volt-amperes from the grid and supply real power to the grid....
solenoids are cool's user avatar
1 vote
0 answers
62 views

How does the electrical power from the output of a generator vary after a fault?

I know that after a sudden generation/load variation there is an imbalance between mechanical power and electrical power at the borders of generators which causes a frequency change according to the ...
Samuele Benito Di Gioia's user avatar