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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58 views

How is AC load distributed across on-site generation and the utility?

I’m trying to understand the physics behind AC load distribution when distributed on-site generation is installed and the load is also connected to the grid. In the diagram below, I have a building ...
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5 V home network

I'm planning on adding multiple IoT devices in my house, and I'm looking for an elegant solution to power them all. They'll all need 5 V, a small number of them (cameras) would draw up to 2 ...
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1answer
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Cost of systems to connect a 6 MW wind turbine to the grid

Assumptions: The turbine is pretty close to an American (US) grid. National Grid will charge $50,000 to install isolation switches and remote control systems that let the device connect to the grid. ...
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Impact of Interconnection of One Energy Generating Plant At Another Generator Plant's Generator Bus Bar(PV Bus Bar)

As the scheme attached below, we're interconnecting 5.5 MW of generated power of upstream project(Around 2 km Away from the Interconnecting Switchyard) to the Generator Bus Bar(PV Bus Bar) on 11 kV ...
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1answer
68 views

Has there ever been a case of overvoltage in a power grid?

Every now and again we read about blackouts, where the voltage of the power grid drops and the infrastructure is paralyzed. But have there ever been cases where the power grid experienced a massive ...
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1answer
62 views

Where will the grid-tie power go if it's not connected to the grid? [duplicate]

What will happen to the extra power that the grid-tie inverter is producing if the demand is less than what the load needs? I have this planned system that I will be implementing soon. The good thing ...
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5answers
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Why/when is AC-DC-AC conversion superior to direct AC-AC conversion?

I am currently studying wind power and the power electronics used for it. In wind power a generator is driven by wind, thus the resulting power is of widely varying frequency and amplitude. The power ...
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2answers
34 views

Current flow in step-up and step-down transformers of a power system

I have a question with respect to the current flow in step-up and step-down transformers. AC transformers work only when an alternating current flows through the primary so as to induce current in ...
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Interpretation of IEC 61000-3-6 (Assessment of emission limits for the connection of distorting installations to MV, HV and EHV power systems)

Based on the installation I want to calculate the acceptable current harmonics related to my installation. IEC 61000-3-6 says: For each customer only a fraction of the global emission limits GhMV+...
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4answers
477 views

Is there a minimum amount of electricity that can be fed back into the grid? [closed]

This is not fully related to electrical engineering, but I have been reading lately about Feed-in-Tariffs and solar energy production and I cannot find any information on the amount of energy that can ...
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101 views

Volume risk in an electricity market

I have been reading lately about electricity markets and I have stumbled upon the term "volume risk". Volume risk is often used to denote the phenomenon whereby electricity market participants ...
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4answers
3k views

Purpose of cylindrical attachments on Power Transmission towers

Attached below is an image of a Power transmission pole. What I am interested in is the cylindrical shaped objects attached to the transmission tower. Some other observations and relevant information:...
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1answer
147 views

The life of a high voltage line

In my neighbourhood, a 220 kiloVolt high voltage line is being renovated. It seems that they are replacing the cables, and they also may do some other maintenance. This, however, gave rise to some (...
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61 views

Why does reactive power change when a secondary source is connected?

When load was varying very little, PV supply was turned ON. Inverters used can give power factor(PF) in the range of [-0.8, -1] and [0.8, 1.0] Table 1 shows power requirement when only grid was ...
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1answer
73 views

What is the difference between commutation number and pulse number in?

My question is about bridge rectifiers in power electronics. I guess the jargons are too vague, so i quote the exact definitions from my book which i don't understand at all: m represents the ...
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Is the duck (curve) still a duck? [closed]

In 2013 the California Independent System Operator (CAISO) published this image, dubbed it "the duck curve", and took the internet by storm (or, at least the part of the internet that tracks trends in ...
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2answers
4k views

When a wind turbine does not produce enough electricity how does the power company compensate for the loss?

I heard once that when a wind turbine power plant doesn't produce enough electricity the power company's are sometimes forced to turn on a couple of jet engines in order to compensate for the loss, is ...
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1answer
60 views

What determines the phase difference between two voltages at an AC bus?

At an AC bus, the power flow is given by the following equation : In normal operation, the voltages (V1, V2), as well as the inductive resistance (x), are constants. So the parameter δ defines the ...
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1answer
24 views

Peak Period Forecasting in electric grid

I am currently working on the day ahead load forecasting using a regression model over a microgrid level. I wanted to know is there a way I can detect peak period i.e period where demand is high from ...
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1answer
42 views

Load Profile plot from Smart meter data

In electrical engineering, a load profile is a graph of the variation in the electrical load versus time. I am currently working on Smart meter data having reading an interval of 30 min i.e power ...
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1answer
40 views

Distribution-side voltage regulation and Low voltage ride through (LVTR) curve

Nowadays, I see that photovoltaic systems have Low-voltage-ride-through capabilities. So in case of a fault, when the voltage is decreased, they remain connected to the grid and provide reactive power ...
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1answer
84 views

How much power do power stations in parallel supply?

In modern power systems, the power is supplied by effectively connecting multiple generators in parallel. However, not all these generators are equal, some stations supply more power than others (I ...
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2answers
670 views

Why is the socket voltage in Mexico 127V?

As per the title, this is a very specific figure. Is there a reason it's 127 instead of 120V or 130V?
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2answers
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In North America, why is the wide prong neutral instead of the narrow prong?

The wide prong is neutral on 15 amp US power outlets. Is there a reason it was designed this way, or could the narrow slot just as easily have been neutral instead? Was this design decision ...
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1answer
56 views

Connect a switching power supply to the EU grid

I just bought a switching power supply which is supposed to be connected to the power grid using three connections (Neutral, Live and Ground). Unfortunately, all common cables can be plugged into ...
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1answer
109 views

Reactive power compensation through grid connected inverter

I recently designed a bidirectional DC-DC charger for an Electric Vehicle (EV) battery. I would like to focus on the inverter control. In this application, I designed the inverter to have unitary ...
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1answer
54 views

how could i decrease residual voltage of 11KV bus that Is created by direct online 9MVA induction Emotor?

We have power grid 11KV (bus A & bus B) with 2 incoming and one coupling breaker between them;bus A have a outgoing that feed 9MVA induction Emotor; incoming A and B and coupling Equipped with ATS ...
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50 views

How do single-phase inverters know if they're in sync with the grid after they're in parallel?

How can one inverter, once its output is already in parallel with the grid, measure the phase difference between the grid and itself? Any current or the variation in the current flowing on its output ...
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1answer
854 views

Why does a wind turbine deliver reactive power to the grid during no winds or when turbine is stopped?

An answer to a previous question explained that a turbine in stop mode may deliver reactive power to the grid. It also takes active power from the grid to run its control system, lighting system and ...
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1answer
317 views

Why does a fault lead to increased reactive power demand?

When we have a fault, say on one line out of three, the reactive power demands increase, which leads to voltage instability if the source can't provide it. My question is, what causes reactive power ...
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1answer
93 views

Understanding power system lines and their capacity

First of all, I am no engineer so forgive me if I confuse concepts (or show lack thereof). When constructing the power grid, I was wondering about the following: Do engineers use 'standard lines' (...
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1answer
81 views

How do I keep DC voltage high in a building grid?

I'm trying to create an off-grid installation. I have 200W PV panels, 20A charge regulator and two 150Ah, 12V batteries in parallel. How can I keep the voltage constant through all the grid in the ...
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1answer
84 views

The materials used in an electrical grid going from power station to house [closed]

In getting an overview about how Electrical Grids work, I was hoping to connect the dots from voltage up to the materials (used in modern electrical grids). I am wondering if one could outline ...
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2answers
239 views

Identification of a part on a power line's lightning arrester

I recently spotted an arrangement of wires on a lightning arrester on top of a power line. The power line is IIRC a 110 kV, 16.7 Hz, two phase line for railway systems. The lightning arrester is of ...
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3answers
2k views

Do electricity meters contain inverters?

In Germany the low-voltage grid is 0.4kV whereas the plugs in flats have 230V. Who is responsible for this conversion? Smart meter?
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1answer
50 views

What may be the consequences of AC frequency variations on powerline network adapters [closed]

There has been several reports lately of variations of the main frequency of AC current in European households. What do you think could be the consequences on network signal when using network over ...
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5answers
12k views

Serbia, Kosovo power grid row delays European clocks. Why?

According to this article (and a lot more published today on the same topic), Kosovo electricity net production balance has decreased during the last weeks. This has led to a small deviation of the ...
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1answer
76 views

How is the inverter connected to the grid?

I just finished circuit designing of an inverter which converts 440V DC to 230V AC. Now my manager asked me what kind of connectivity does it has. I answered him: "The current connectivity is AC as ...
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1answer
33 views

Low voltage grid frequency with renewable feed-in

If a low voltage grid's consumption equals to that grids renewable energy production, does it mean the transformator basically does nothing, like an open circuit? Are grid-tied inverters (smart) ...
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1answer
41 views

PV energy feed-in to the grid

I'm reading about integrating PV into legacy grids, and I saw the following scheme: Left side is middle voltage grid, and right side is low voltage grid (400V AC). It is talking about communication ...
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1answer
84 views

What are important metrics of high voltage power lines? [closed]

Upfront: I am not an electrical engineer and therefore apologize upfront if I am asking a stupid question. TLDR; What are important / relevant metrics of high voltage power lines that can be ...
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35 views

Very low network impedance close to 13th harmonic frequency

I carried out a frequency scan of an electrical network model with a proposed 220kV transmission line. Addition of this line lowered the system impedance to very low value (to 3 Ohms) at 13th harmonic ...
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82 views

Why did the Tesla battery in Queensland respond to grid frequency? Why isn't this stable? [duplicate]

The RenewEconomy article Tesla big battery outsmarts lumbering coal units after Loy Yang trips details the recently installed Tesla battery in Queensland Australia's response to a sudden change in ...
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3answers
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Why do underground cables “require a higher degree of reactive power compensation” than overhead lines?

I was reading a brag sheet for a certain company's giant transformers, and I came across this sentence: Furthermore, in some regions, the existing over head lines are being replaced by underground ...
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3answers
135 views

Feeding energy to the power grid

I am doing a research about the electricity grid and a marketplace where neighbours can trade energy with each other. I found out if your PV cell has excess energy you can with an inverter put it ...
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1answer
2k views

What is the purpose of the cylindrical layered conical discs in power stations? [duplicate]

You can see them everywhere. On towers of overhead lines, in power stations, converter stations, transformer stations, etc... Sometimes they are rubber, sometimes metallic, sometimes glass, sometimes ...
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1answer
57 views

What is the range of a direction protection relay?

I am modeling a hypothetical backup protection system for a power transmission grid and need to know if a directional relay can detect a fault if there are multiple lines and buses between the relay ...
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1answer
50 views

Looking for time-series grid data set

The electric power grid consists of many buses, with generators and loads connected to each bus. The so-called operating point of the system consists of the voltage magnitudes, Vn, and voltage phase ...
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2answers
102 views

Power system - Economic dispatch

Quick concept related question, I have a system with 5 generation units and I have to find the maximum demand that the system can support and still be N-1 secure. their max outputs are: Unit A= 155, ...
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0answers
2k views

Detecting AC power flow direction [closed]

I'm willing to design an AC power meter, which can measure power from a solar inverter to the utility grid and vice versa. I am using a grid-tied solar inverter to supply the load. This meter should ...