Monthly Archives: January 2018
what is Anti islanding protection in inverter of photovoltaic electricity
This is a good question about a popular topic.
First, it is important to understand a few things about the ac power grid, how it works, and how it protects itself when faults happen.
Traditionally, the grid was an interconnection of large generators operated by utilities, who had plenty of engineers, operations, and maintenance personnel. Basically, you could say that all parts of the grid – down to point that it connects to your home or office – were owned and operated by technically skilled people.
“Back then” it was understood that each generator connected to the grid would receive a full engineering review to make sure that it responded as intended when a fault (like a lightning strike) occurred on the grid.
Enter the ‘modern’ times, in which generators can be solar inverters, wind generators, industrial co-generation, etc. It was determined by the electric power engineering community that ‘small’ generators should be required to disconnect from the grid if a fault out on the grid occurs. This would keep the small generators from ‘back-feeding’ into a fault and creating an even more hazardous situation. It also requires that the small generators not operate to serve load in an ‘island’ separated from the rest of the grid.
In reality, intentional islands are allowed, if the appropriate steps are taken to be sure the grid itself is not being back-energized. But, unintentional islands are absolutely forbidden. (They are bad bad juju for the grid.)
Most inverters detect the islanding condition by looking for some combination of the following:
1. A sudden change in system frequency.
2. A sudden change in voltage magnitude.
3. A sudden change in the df/dt (rate of change of frequency).
4. A sudden increase in active output power (kW) well beyond the expected ‘normal’ level.
5. A sudden change in reactive output power (kVAR) well beyond an expected ‘normal’ level.
Depending on their internal control programming, one or any of these events could indicate that the small generator and some amount of load have become disconnected from the grid. (For example, it could be just your home with its PV system, or it could be your whole neighborhood disconnected as a block from the larger grid.)
When this island condition is detected, the small generation sources trip offline.
There are specific performance requirements for distributed generation defined in IEEE Std 1547, which cover the time in which anti-islanding protection should operate, and what levels of parameters define abnormal conditions.
As for the internals of anti-islanding protection in inverters, they specifically use a phase locked loop (PLL) with a small amount of positive feedback in its control loop to quickly and continuously check the grid connectivity. Look for ‘anti-islanding’ protection papers from Sandia National Labs.
HHO gas injection-?
I live in South Africa. Fuel costs rose by more than 30% this year. Found a lot of negative reviews re HHO gas injection. As a theory it should work same as pushing compressed air (turbo) into the intake for more power. If the power is not used to increase speed would it then not increase consumption. Any one who actualy have installed HHO out there.
Yes, I have and several friends, co-workers and family members.
There are many factors involved in whether an HHO generator will work well or not. The major factors are:
1. What are the electrodes made of, how well will they conduct electricity and how quickly will they corrode?
2. What electrolyte mixture are you using in the water (electrolyte is required to make the water conduct electricity to split the hydrogen and oxygen)
3. How much oxygen are you involving in the gas out to the engine?
4. How many o2 sensors does your vehicle have and how will they react to the extra oxygen they will detect? (sometimes the o2 sensors will detect more oxygen and increase your fuel ratio to compensate for it – I personally have not had this problem, but have heard others record it)
Speaking from my personal experience with the generator I now built, I have literally TRIPLED my gas mileage.
Potential hazards include:
1. Chance of exploding HHO gases if mis-used.
2. Blowing fuses.
3. Water damage to the exhaust over time.
4. Water in the engine – if you are really really careless.
Additional: Common “problems” thrown at you by the nay-sayers, and the narrow-minded smug:
1.*** It takes more electricity to produce than it gives in return with energy.*** = TRUE.=
That is why these are being used along with gasoline engines! (come on folks! Think a little).
The electrolysis here is powered by the alternator from the combustion of gasoline. Because the product is HHO (which is 3 times more combustible than gasoline) – less gasoline is required to achieve the same speeds as before THUS – more MILES PER GALLON.
2. ***It’s a scam*** = False=.
You might as well call Flashlights, Airlines, Solar Power and Refridgeration scams also. All science is first denied by the narrow-minded. Flip through a good history book, then learn some Chemistry! The electrolysis of water produces Hydrogen. Hydrogen and Oxygen (when not combined in H2O formula) are highly combustible. This can be used in internal combustion engines.
Yes, it takes additional battery power if you want to do this solo without gasoline – but doens’t all science require some work on our part? Stop being so Lazy!
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What is the best way to transition away from fossil fuels?
Should society transition directly to electric vehicles driven by solar energy or nuclear energy? Is there a role for biomass energy as an intermediate step to supply synthetic fuel while solar/nuclear capacity is being built?
Heh, solve the electrical power transmission and storage problems while at the same time putting a price on burning fossil carbon compounds to more accurately reflect their real long term costs to society.
The best way would be to re-think everything from the ground up, literally. Vehicles do not need to be smaller, slower, and less safe to be more energy efficient. Materials science has come up with many useful things that, taken together, add up to amazing, if we put them in vehicles. Carbon fiber for lightweight strength; metal foam, 99% empty space, for a gas tank that prevents a fuel tank explosion; puncture-proof tires; radar, sonar, and infrared sensors coupled with driving software; city cars: small, rather short-range vehicles that might drive themselves and be part of a robot rental fleet. Prevent humans from driving in a large city – let traffic AI’s take over, as it’s essentially been demonstrated they can already do a better job of moving vehicles through the city. Size the rental to the number of people. Push vehicle weight to a minimum. Streamline. Use all the electromagnetic and other tricks to save and re-direct energy.
Biofuels are carbon neutral. Historically their problem has been that the crops we’ve tried to use are too expensive to society for many reasons. We’re pretty good with hydrocarbon-burning engines, though. However, to make it worthwhile, we’ll have to figure out how to convert “waste/useless” biomass into fuel. Not biomass we need to plow under for fertilizer, or need as part of a functioning ecosystem. It’s an interesting idea, but I suspect the long term economics argue against it, and possibly even the medium term. Climate change is very likely to decrease the amount of land we have available for farming, and very unlikely to increase it, or even leave it unchanged. Population is surging. Biofuels don’t seem to be a really good long-term growth prospect. They could/might provide a little indefinitely, for small engines – lawnmowers, RC toy/hobby vehicles, generators…
Fuel cells are a different way to go. They could replace gas, batteries, a very long cord, whatever in any number of applications. From theory [ref 1] through costs [ref 2] to applications [ref 3] we are making fuel cells more practical. Let them stand for the whole range of new energy technologies we are developing. They are another way.
Finally, in the US, I believe we need to re-think how we do all this research. We will get the best results from a blend of private enterprise, government research, and public-private partnerships, like most of the rest of the world uses. We need to take off our ideological blinders, share a little healthy pragmatism, and put public and private money into getting some useful big-ticket things done.
That’s a sketch of what I think some of the obvious best ways are. I do not think they are the most likely things to happen in the short term 5 – 10 years, but being optimistic, I hope for the medium term, 20ish years. In the longer term, 50+ years, what I truly think is our best bet is to have a massive presence in space, with most major industry moving off-planet. With solar panels and rail guns, we could exploit the nearer moons and asteroids, and fire materials to earth. This level of operating tech would allow us to put sunshades above earth to create a practical climate control, even if we can’t manage actual weather control.
WHY SHOULD SOMEONE SWITCH TO SOLAR POWER?
I understand that it offers tax breaks and it saves you money. I also, understand that it is better for the environment, but what other reason should some one switch to Wind or Solar power?
Hi Trumpetgirl, here are some considerations. If you invest properly in solar power today and take advantage of any grants and tax incentives, even if your electric rates do not go up as they are forecast too, you will get your money back over time, well within the lifetime of the equipment, and sooner if there is a rate increase in the future. There are also enviromental benefits. At one time there was an argument that a solar panel will never produce as much power as was used to manufacture it. First of all, this is not correct. The, “Embodied Energy,” in a solar panel is earned back in 2 – 6 years, depending on the type panel, where the raw materials were shipped from, and how it was installed and used in the end. Most panels are warrantied to last at least 25 years, and most last much longer than that. But the argument is not important anyway. We have been living with electricity for over a century now, so it isn’t going away anytime soon. The question is, “What is the best way to produce it?” If you build a panel, and put it along side a similar sized natural gas fired turbine generator for example, which earns back its embodied energy sooner? The answer is the gas turbine never does, because once you build it, ship it and install it, you now have to feed it natural gas for the rest of its life, so it keeps on digging itself a deeper and deeper embodied energy hole that it can never crawl out of. At least the panel has a chance to get even environmentally. So manufacturing and using solar panels in the end releases less pollution into our environment.
There are also mechanical and political benefits. We all know after the oil embargo of 1973, and the gulf war what it means for our country to rely on foreign oil. Wouldn’t it be nice if we only shipped in 20% of our energy instead of 60% the next time something like that happens? Our home has been powered by the wind and sun for years now, but we still remain connected to the electric grid. Last year alone there were two power failures in our county that lasted about a half day each. In both cases, we were not aware of them because our solar array kept on feeding the house. It’s difficult to put a price tag on something like that. Did you know that there are over 100,000 homes and businesses in the United States alone that use some level of solar power to operate their electrical devices, that’s good news.
Beyond the mechanical, political and environmental benefits however, lies a less obvious benefit, the social benefit. Right now we pump oil out of the ground, and mine for coal. The process of getting those materials to market involves shipping, military escorts and other activities that use up a good portion of that energy as well as putting lives at risk. Jobs in alternative power are higher tech than jobs in coal mining, oil drilling and shipping, and there are more of them. Using more alternative power would require us to put more people to work, and increase our education base because the work involved requires certain skills. I would personally like to take all those people out of the coal mines, send them to school and put them to work building solar panels. Nobody would have to die again in one of those dark holes in the ground trying to find food for our hungry power plants. They could work on a factory floor where they would not be exposed to coal dust, radon and other toxins and dangers. Most of our solar and wind resources are spread pretty evenly over the middle half of our globe, so everyone has access. This puts people in Bogota on a more equal footing with people in Boca Raton by giving them access to electricity, heat and clean water, and the education to use the solar, wind and biomass resources that provide those things. Oil, coal and natural gas is generally piled up in a few places, such as Russia and the Middle East. This gives those countries and the richer governments that rule them more horse power in bargaining for the other resources of our planet. These are the things that wars are made of.
There are other reasons, but I think you get the picture. For us, solar energy has become something of a hobby It will probably never save us any real money, utility power in most places is really very inexpensive, but it’s a little like growing your own tomatoes. It’s usually cheaper to buy them at the grocery, but lots of people go to the work and expense to maintain a garden instead. We just grow electrons in ours. If you really want to learn more about the subject, there are some great sources to look into, I will list some below. Good luck, and take care, Rudydoo
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