50Hz 230 volt power in a 60Hz world

[SolarPro]

The dump load is apparently needed in order to create a stable 50 Hz microgrid. They're testing 50 Hz microinverters, perhaps for the European market, at a US facility. Since the US has a 60 Hz grid, they have created a 50 Hz microgrid for beta test or product development purposes.

That's the way I understand it, anyhow. Other than putting the dump load in a tank of water, I don't have idea how you convert that waste energy to useful work. Interesting question though.

 

[Besoeker]

Other than putting the dump load in a tank of water, I don't have idea how you convert that waste energy to useful work. Interesting question though.

Stick it back into the 60Hz grid.
I've explained a couple of methods for doing so.

 

[tallgirl]

From post #1:

A dump load doesn't sound like grid tied.

Nope, it's 100% grid tied. I'm about 40 or 50 feet from the electrical closet, and another 10 feet from the service panel in that closet.

Plenty of grid tied systems either have or require dump loads. The ones that tend not to can have problems with voltage collapse because they regulate power into the system by shutting inverters down. My preference is to keep the inverters running as much as possible.

 

[kwired]

Forgive me, I don't know much about PV.

I can understand it looking for the grid frequency so it can synchronize its output to match the grid when interconnected, but from what has been said here it appears that this thing will not work properly if there is no grid to reference??

It would seem useless to me and especially to people with little or no electrical knowledge, to have a source that must depend on the presence of the grid before it can operate. Say the utility power fails - people are going to ask why can't that solar powered system be used for standby power? That is kind of an assumed benefit of that kind of system to people with no technical knowledge of how it actually works.

 

[tallgirl]

K,

There are systems that will work without the grid being present. It's up to the customer to decide how they want their system to work and make the appropriate choices.

 

[kwired]

K,

There are systems that will work without the grid being present. It's up to the customer to decide how they want their system to work and make the appropriate choices.

I kind of had a feeling that was the case.



Not trying to be a thorn in your side, but why do you come asking for advice then tell a responder they don't know anything about PV systems, when the real advice you were asking for is how to convert from one frequency to another? The person you shot down IMO is one of the better knowledgeable people on this forum able to give you advice on how to make such a conversion.

 

[ggunn]

Forgive me, I don't know much about PV.

I can understand it looking for the grid frequency so it can synchronize its output to match the grid when interconnected, but from what has been said here it appears that this thing will not work properly if there is no grid to reference??

It would seem useless to me and especially to people with little or no electrical knowledge, to have a source that must depend on the presence of the grid before it can operate. Say the utility power fails - people are going to ask why can't that solar powered system be used for standby power? That is kind of an assumed benefit of that kind of system to people with no technical knowledge of how it actually works.

Having a grid tied system is not about having power when the grid goes down, it's about generating power when the grid is operational to offset your electric bill. A PV system which will work when the grid is down requires a sizeable and expensive battery bank. For most people, grid outages are rare and usually of short duration, so it's not worth it to them to double or triple the cost of their system in order to have power from it during outages. Depending on local incentives, grid tied PV may pay for itself in ten years and become cash flow positive, while a grid interactive battery backup PV system will generally never come anywhere close to doing that.

That said, I have heard (many times) of unscrupulous solar installers that don't make all this understood by their prospective customers, even to the point where systems get installed and inverter companies are flooded with "warranty calls" because system owners did not know that their PV would shut down during a grid outage.

 

[kwired]

Having a grid tied system is not about having power when the grid goes down, it's about generating power when the grid is operational to offset your electric bill. A PV system which will work when the grid is down requires a sizeable and expensive battery bank. For most people, grid outages are rare and usually of short duration, so it's not worth it to them to double or triple the cost of their system in order to have power from it during outages. Depending on local incentives, grid tied PV may pay for itself in ten years and become cash flow positive, while a grid interactive battery backup PV system will generally never come anywhere close to doing that.

That said, I have heard (many times) of unscrupulous solar installers that don't make all this understood by their prospective customers, even to the point where systems get installed and inverter companies are flooded with "warranty calls" because system owners did not know that their PV would shut down during a grid outage.

Thanks for that information, like I said I don't know much about PV systems, they just are not around this area for the most part. Other alternate and grid connected sources are starting to pop up here and there, but I have not been directly involved with any of them so far, so I haven't even experienced any similarities from those systems either.

Wind energy is becoming a big thing locally especially with commercial wind farms. Funny thing is there is plenty of wind during winter months, but summer months is when there is less average wind and the load on the grid is highest at that time of year locally, so I am not sure just how convinced I am about wind being a good alternative - locally anyway.

 

[ggunn]

Thanks for that information, like I said I don't know much about PV systems, they just are not around this area for the most part. Other alternate and grid connected sources are starting to pop up here and there, but I have not been directly involved with any of them so far, so I haven't even experienced any similarities from those systems either.

Wind energy is becoming a big thing locally especially with commercial wind farms. Funny thing is there is plenty of wind during winter months, but summer months is when there is less average wind and the load on the grid is highest at that time of year locally, so I am not sure just how convinced I am about wind being a good alternative - locally anyway.

Yeah, the Achilles' Heel of renewable energy is storage, or the lack of it.

 

[Besoeker]

Nope, it's 100% grid tied.

So what's the question you want answering?

 

[weressl]

I kind of had a feeling that was the case.



Not trying to be a thorn in your side, but why do you come asking for advice then tell a responder they don't know anything about PV systems, when the real advice you were asking for is how to convert from one frequency to another? The person you shot down IMO is one of the better knowledgeable people on this forum able to give you advice on how to make such a conversion.

Because she is from Austin:lol:

 

[Besoeker]

Not trying to be a thorn in your side, but why do you come asking for advice then tell a responder they don't know anything about PV systems, when the real advice you were asking for is how to convert from one frequency to another? The person you shot down IMO is one of the better knowledgeable people on this forum able to give you advice on how to make such a conversion.

Two sayings come to mind.

"you can take a horse to water etc..."

"The beginning of understanding is the acknowledgement of ignorance."

 

[ggunn]

Because she is from Austin:lol:

Hey, I resemble that remark!

 

[weressl]

Hey, I resemble that remark!

Yess, you do

 

[tallgirl]

I kind of had a feeling that was the case.



Not trying to be a thorn in your side, but why do you come asking for advice then tell a responder they don't know anything about PV systems, when the real advice you were asking for is how to convert from one frequency to another? The person you shot down IMO is one of the better knowledgeable people on this forum able to give you advice on how to make such a conversion.

In this particular instance, he has little or no useful knowledge.

Grid-tied systems have requirements that are intrinsically hard to satisfy because the equipment is designed very carefully to NOT connect to something that isn't the electric grid.

The indication that he had no clue was suggesting that the 50Hz power be rectified and then converted back to 60Hz with a 4 quadrant VFD. That =can= be done, but controlling how much power is converted becomes its own problem. In particular, there still has to be a 50Hz signal that behaves sufficiently like the electric grid (or is stout enough that it can't be "moved" by the anti-islanding logic in the inverter) to keep the inverter from disconnecting.

A far simpler solution, and one that's guaranteed to work is to set the system up for AC coupling. Inverters that can AC couple are readily available and solve all the problems with a minimum amount of equipment and handle the change in the direction the power is flowing very automatically. They're also listed for the purpose and meet the appropriate UL and IEEE standards.

 

[Besoeker]

The indication that he had no clue was suggesting that the 50Hz power be rectified and then converted back to 60Hz with a 4 quadrant VFD. That =can= be done, but controlling how much power is converted becomes its own problem.

It isn't a problem.

 

[weressl]

It isn't a problem.

Not unless the person making that statement doesn't know what they are talking about.

 

[Besoeker]

Not unless the person making that statement doesn't know what they are talking about.

You have to wonder........

 

[weressl]

You have to wonder........

Isn't it transparent?

I mean plain ignorance is just not knowing, but trying to assert the superiority of your knowledge by calling other stupids is well, is just plain stupid.

 

[Besoeker]

Isn't it transparent?

I mean plain ignorance is just not knowing, but trying to assert the superiority of your knowledge by calling other stupids is well, is just plain stupid.

I was trying to be nice.........