Questions tagged [power-grid]

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

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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 ...
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Effect of 340ms drop in power on complex electrical equipment? [closed]

I work in the technical department responsible for medical equipment at a hospital. We recently got a rather interesting conundrum on our hands that none of us really knew the answer to. Basically, ...
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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 ...
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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 ...
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1 answer
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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 ...
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1 vote
1 answer
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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 ...
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1 vote
1 answer
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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 ...
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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 ...
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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 ...
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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
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MV grid topology?

In the vast majority of cases, a resonant grid (compensation with Petersen coil) is adopted in MV grids. Grid capacitance is compensated by the inductive component of the Petersen coil. Since cables ...
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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 ...
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1 answer
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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....
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Where are power quality disturbance classifiers and detectors useful?

Power quality disturbance (PQD) classification and detections algorithms constitute a decent part of the literature in Electrical Engineering. Where are these classifiers and detectors useful? Grid ...
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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 ...
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1 vote
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Mechanic and electric power after imbalance in power system?

After a power imbalance (for example a generator disconnection) in the electric grid, generation and consumption are not equal. This causes a dynamic transient in generators described by the Swing ...
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Is the power frequency characteristic of a network almost constant?

When a transient phenomenon happens in an electric power grid, the network reacts to this deviation with a power-frequency characteristic (MW/Hz). Reading the following paper ''Analysis and ...
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3 answers
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Self regulating effect of loads for frequency control

How does power absorption from loads depend on frequency? I know that during a frequency deviation in power grid, there are primary reserves which control the frequency, but I know there is also the ...
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1 answer
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Who gains money when domestic photovoltaic electricity is injected on the grid? [closed]

As an equity measure to ensure that everyone pays for the grid use, in multiple places we, the citizens/consumers, don't get refunded when we inject our excess photovoltaic production into the grid. ...
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2 answers
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How are primary reserves activated for frequency control?

How are primary reserves activated for primary frequency control? In particular I have the following doubts: Is there a frequency threshold where each of them are automatically activated or they are ...
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1 answer
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Rated nominal power of generation with respect to load condition

In the electric power grid generation and consumption must be always the same. For sure the load change continuously in time, therefore an equal generation change must always correspond to the load ...
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what is the surplus-control of generation?

Reading the ''P1 – Policy 1: Load-Frequency Control and Performance'' document, published by UCTE in 2009 (it is available on internet for all) I noted that there are many contributions to Load-...
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Is the generator inside thermal power plants a synchronous type or asynchronous one? [closed]

Are thermal power plants connected to the electric power grid based on synchronous generation or asynchronous one? If a mix, which is the main one?
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nature of the load connected to the electric power grid

I know that loads can be modeled either as constant impedance or as fixed power P and Q. I also know that the majority of the loads are constant impedance type but I don't know exactly the percentage. ...
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Can loads absorb more power than needed/requested?

I was designing the governor of a generator, implementing in Digsilent Powerfactory a 1 bus grid like that in the picture. The generator delivers 350 MW and the 3 loads withdraw respectively 25 MW, 25 ...
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4 votes
5 answers
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Why do Americans use fuses and not differentials and breakers like Europeans do?

I recently moved to North America, and I was wondering why the houses here seem to be protected by fuses rather than breakers and differential switches like we have in France for example. It would ...
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3 votes
2 answers
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Frequency behavior in the electric grid

Is the frequency behavior equal in very distant interconnected points of the grid? For example, if there is a sudden generation drop in Portugal, is the frequency behavior in Portugal exactly the same ...
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1 vote
2 answers
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Voltage regulation with reactive power

Supposing to have a generator located in the electric grid providing a voltage regulation controlling its reactive power output. If the voltage on the grid increases near the generator, should the ...
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1 answer
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Difference between a relay and a fault passage indicator (FPI)?

What is the difference between a fault passage indicator (FPI) and a relay (for example relay 50, 51, 67N) ? Are they the same thing?
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4 answers
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How does a power plant's increased output translate to the Volts, Amps and Watts on the power lines?

In the context of a power plant, that wants to output more electricity. If the formula for Watts is V*A=W, does Voltage or Current get increased to supply more ...
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3 votes
1 answer
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Why does reactive power injection mitigate sagging grid voltage?

I understand that reactive power injection can be used by generators to support the grid voltage when sagging, but I’ve never understood why this works. I thought it could be charging transmission ...
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1 vote
1 answer
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Why a voltage drop at the busbar's generator?

I was testing the effects of distributed generators on our grid. To do so, I inserted a PV generator of 90 MW PURELY ACTIVE (power factor = 1) as in the picture. I performed a quasi-dynamic simulation,...
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How are locations of power plant and distribution substation decided?

I'm trying to design a basic electrical system of a large island and I'm having trouble deciding for the site locations. The existing grid of the island has a diesel plant located near the town but I ...
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How can grid frequency dropping lead to grid failure [closed]

From what I understand, frequency variation indicates generation-load imbalance. In particular, when frequency decreases the load demand is greater than generation. Wouldn't this just lead to the ...
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How is a line commutated inverter different from a grid-following inverter?

The U.S. Department of Energy provides this definition of a line commutated inverter: An inverter that is tied to a power grid or line. The commutation of power (conversion from direct current to ...
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How do generation schedules / load schedules work on a power grid?

I've noticed that some generating stations have "generation schedules" and similar schedules also exist for load distribution stations. They usually have a MW amount telemetered to the ISO (...
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1 vote
4 answers
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Electrical phase in a power grid and power transmission

I'm very new to the study of power grids and I'm having some trouble understanding some very basic concepts. I have been looking at the problem of synchronisation on power grids and I'm not quite sure ...
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How to calculate energy added to grid using active and reactive power?

I have recently installed solar system that adds energy to the grid. My utility company has installed bi-directional meter at my place to record energy consumed as well as energy added to the grid. ...
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Battery cost LCOE and carbon emission by hourly. Validation of calculation approach

I am compiling a report and trying to validate my understanding of using power correctly to multiply with constants like price and emission in kg weight. Please point out if the approach below is ...
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3 votes
1 answer
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How does the grid handle small deviations of power consumption when most of load is regulated?

This is a continuation of this question. Suppose we have a grid which distributes say one gigawatt total power and all this power is perfectly fully consumed by electrical devices. However all ...
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2 answers
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Why does it take such a long time to build a new power grid transformer?

From time to time, when people are discussing the consequences of power outages, like the ones from the Texas winter storm or a hypothetical catastrophic space weather event (Carrington event scale), ...
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3 votes
1 answer
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How can wind turbine be used to frequency control in a grid?

I was listening to an interview (sorry don't have the source) from the Mexican's minister of energy, where he mentioned 'Wind turbines are useful even when the wind is not blowing because they can be ...
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Electronic earth

I just want to know basic information about it and why it is not to be connected with main ring of electrical plant. If there are any references for it i will be grateful.
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5 votes
1 answer
246 views

Why can generators be damaged by series capacitors (SSR)?

Specifically I am talking about generation that uses steam to generate turbo spin (steam cycle) like nuclear or natural gas plants. I have been learning about Subsynchronous Resonance (SSR), which is ...
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1 vote
0 answers
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Calculating the line-to-neutral voltage of a generator

A three-phase generator is connected to a strong grid with line-to-line voltage 14 kV and frequency 50 Hz. The generator is rated at 15 kV and 180 kVA. The resistance in the windings is 2 Ohm/phase ...
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1 vote
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How to use the rate of change of frequency equation to calculate frequency drop in a grid based on lost generation

My question involves calculating the frequency drop in a power grid when a load is lost. The closest question I have found to mine is, Change in frequency in a grid that has lost generation? Based on ...
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17 votes
4 answers
9k views

How can energy "physically" be fed back into the grid?

I have found some similar questions (below), but I am still having issues understanding what is "physically" happening when energy is "fed back into the grid" and the equipment ...
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2 votes
2 answers
441 views

Effects of low voltage on power grids?

I understand that if load is suddenly ramped up on a power grid: A sudden increase in current is caused by adding these parallel loads to the circuit. The current increase thus increases the torque ...
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3 votes
3 answers
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What happens with the power grid if nobody uses electricity?

How much electricity does consume electric system by itself? Just to have an option at any moment to plug in anything at socket at home and turn it on. There are huge power plants to convert high ...
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29 votes
7 answers
8k views

Why do power grids tend to operate at low frequencies like 60 Hz and 50 Hz?

I understand that a two-pole AC generator has to rotate at 3600 rpm (60 Hz USA) in order to maintain a 60 Hz frequency and higher frequencies would require these generators to spin even faster which ...
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