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Australian standards require that your inverter disconnect from the grid if it detects that the grid voltage is too high for an extended period of time. Your inverter may also reduce output power in response to high mains voltage before the voltage is high enough to shut down.
There has been a lot of panic about how the growth of renewable energy is threatening our grid, but one real issue that is getting real industry attention is that voltage surges across much of our aging and inflexible infrastructure are preventing customers from getting the most out of their electricity Solar photovoltaic installation.
Anyone who is educated in this field certainly knows this, but I think most consumers do not understand that the relationship between inverter voltage and mains voltage is very important. When something goes wrong, consumers get a bill showing that much less power is being fed into the grid than they expected, and someone—a solar installer, an electricity salesman, or the grid—gets an angry phone call.
At a recent Clean Energy Council webinar, all four speakers — CEC’s James Patterson, Solar Analytics’ Stefan Jarnason, SA Power Networks’ Travis Kausche, and SMA’s Piers Morton — all agreed that surge is a big problem. complain that they are not getting value for their money from grid-connected solar power systems.
The inverter must operate at a higher voltage than the grid in order for it to export electricity (current flows from a higher voltage point to a lower voltage point, not vice versa). The problem is that every solar installation that feeds power into the system raises the grid voltage slightly – tens of thousands of systems come online on SA Power’s grid every year, and some experience grid voltages that exceed the capacity of their inverters (AS/NZS 4777.1). the standard limits the inverter voltage to 255V).
It’s worth noting that solar power systems aren’t the only cause of surge problems — as Solar Analytics founder Stefan Jarnason says, surge problems occurring at night are proof enough of this.
SA Power Networks strategist Travis Kausche said at a webinar that the state currently has 1 GW of household electricity fed into the grid; Of these, 163 MW were put into operation in 2018, and it is planned to increase the capacity to 300 MW in 2019.
The rise of solar power “makes the dynamic range [the difference between the highest and lowest voltages seen on the grid—Ed.] much larger than if there were only loads on the grid,” Causche said.
What happens when the inverter is about to trip? Customers began to complain, usually to their installers, that FiT’s payment was not up to their expectations.
Everyone can do the right thing, but the system doesn’t work (Image credit: Clean Energy Council Workshop)
It can be fixed, but it’s always better to try to avoid the problem than to keep the relationship with a grumpy client – preventive measures and remedies are the focus of the webinar.
Stefan Jarnason of Solar Analytics says his company’s analysis of 30,000 customers shows that 50 percent of feeders experience 50 or more surge problems per year, when the voltage exceeds 253 V for more than five minutes (compared to when the voltage drops rare). experience 50 or more incidents per year).
The more granular the data records, the easier it is to see their impact on customers, Jarnason says. Solar Analytics images at 5 second resolution clearly show the inverter shutting down due to overvoltage, trying to reconnect, shutting down again, etc.
The orange line shows the system shutting down due to a power surge and then trying to restart (Image credit: Clean Energy Council Workshop)
The problem with networking is that some of the available fixes are difficult to implement on older infrastructure.
Imagine a long feeder line serving many consumers, this means keeping the voltage within acceptable limits for the last consumer, the voltage closest to the transformer will leave very little room for the inverter.
As Kausche explains, if the transformer is new enough and a lower voltage tap is available, the network supplier can only adjust the voltage by changing the tap on the transformer, but most of SA Power Network’s 70,000 low-voltage transformers do not have this capability. transformer upgrades are expensive. Substation transformers are much more capable but do not provide detailed voltage control.
The webinar highlighted the role that solar installers can play in refurbishment, with all three speakers stating that proper installation and setup of inverters plays an important role in preventing complaints.
SA Power Networks has changed its inverter policy to require all inverters installed on its grid to have the Volt-VAR setting enabled (listed as optional in AS/NZS 4777.1) so that the inverters respond more quickly to grid conditions.
The network is also working with other vendors to develop a standard set of solar inverter installations, so at some point solar OEMs and installers have standard profiles across Australia.
SA Power Networks is also trying to shift most of its customer load to noon. For example, off-peak hot water systems can be easily set up if they can be set up remotely, and a “sponge” tariff will be introduced from 2020 to encourage consumers to schedule loads like washing machines, dishwashers and pumps in the middle of the business day. day.
CEC’s Patterson noted that system design, including cable specifications, is also important for managing power surges. CEC polled attendees to see if they liked the idea of an online calculator tool to help installers design solar systems, and it got 100% yes, so we might see it soon.
SMA’s Piers Morton said the impact of the voltage increase has highlighted the need for remote controlled solar inverters that SMA will launch in the near future, saying installers can also benefit by focusing more on balancing the various phases of the system.
If you are a solar system owner and are experiencing voltage surge issues, Finn has written a handy troubleshooting guide here.
Richard Chirgwin is a journalist with over 30 years of experience covering a wide range of technology topics including electronics, telecommunications, computing and science.
When I installed the system in the summer, I was often disconnected. You can literally see the tension building up quickly as the cloud breaks and then pops, shuts off. Just reconnect in a minute.
The same thing happened to me in Mexico. My installer adjusted the shutdown voltage and there have been no problems since. Of course, solar energy has a steep learning curve.
It was easier back then to have my supplier fix it. Since then, no problems. More than a year has passed.
I work in a garage where an inverter was installed, so I know perfectly well that it will fall. There must be many solar panel owners who will never know.
253.?235 is the purpose of approving imported electrical appliances that comply with all new international standards. 100 to 240 volts have no plus or minus requirements, according to SaaS mob 253 v electrical standard any warranty due to heat damage due to high voltage will be rejected. Anything above 245 volts seems to cause these devices to overheat and shorten their life significantly. It’s amazing that responsible idiots allow this to happen. This is a serious safety risk and they must reduce the voltage of the local grid by installing proper transformer infrastructure that can handle solar feedback. The higher the voltage, the less you can send back, and your inverter won’t like the constant high voltage. Assholes are a piece of the pie. So your solar output drops, they can also limit you and kill your feedback. And add to your bill, because your device can’t do anything with the extra voltage except by shunting it, because the heat shortens the life drastically… They’re not doing you any favors at all. Actually skrwd is a bit difficult for you……. I had these bastards run new connection wires to the poles because the old ones were thin and caused voltage to rise. I was up to 251 max during the day. This is far from what we call mains voltage of 235 V, and far beyond the capabilities of new devices. Most newer appliances have a thin wire that burns when heated under high voltage, this usually prevents a house fire, but if the wire doesn’t burn for some reason, it will ignite something on the circuit board and you could burn yourself. from high voltage Direct fire, not equipment failure. The safety device may have failed, but if the voltage is 235 volts, this will not be a problem. with billion-dollar corporations arguing over the app, they know they can get away with murder if someone’s house burns them to the ground… imo, we need to act. 240 hardtop. Distributor. If they can’t, renationalize.
Hi Dean, in the UK it seems we have the same voltage standard as in Australia. I have the same problem with mains power. When we moved here, the RAF base was closed. Years later they turned it back on and that’s when we started having problems with the mains, most of the time in the morning around 7:00 am the switches went off, plugged them back in 3-5 minutes later and they went off again. This will last from 1 to 1 1/2 hours. Some nights are the same. My voltmeter shows 263V when disconnected. The recorded voltage for the week shows that the average mains voltage is 245V. This has 2 consequences, firstly, the surge safety is reduced by 15V, leaving 8V for the surge. Secondly, since electricity is rated in kilowatt hours, this means you are paying more for electricity than you should, since kilowatts = V x amps, adding volts adds kilowatts, which is not good for the consumer, more for utility money. .
It’s worth reposting my earlier post on this topic in August 2020: – The standard set of power quality issues were raised.
(Voltage transients – dips – spikes – dips – interruptions – steady state distortion – flicker and noise).
It will definitely be inconvenient to some extent, but the elephant in the room has not yet been mentioned, but it will cost network customers cash, and the grid power factor (PFR) penalty rate is likely to come into effect soon. .
Advanced features Grid-mounted inverters must meet this requirement in their design, operating in a way that maximizes savings in all areas, including active and reactive power and power factor control. The further PF goes to 1, the higher the reactive power penalty rate will be.
The grid authority will also have the right to instruct the inverter to supply reactive power to bring the power factor into line. This is already common in other places.
Therefore, power factor is of paramount importance in any power generation system serving a load. Every power equation in AC theory includes a V value (voltage) including the power factor PF. We already know that current I is inversely proportional to PF, so if PF is low (less than 1), the current will increase. I is proportional to 1 divided by PF. As a result, the losses in the line I square R increase and the efficiency of the system decreases. IE Higher electricity bills for lower active power consumption.
Learn about power factor. It is the dominant electrical concept for all power generation systems, including rooftop solar inverter systems. This alone could bring the solar PV rooftop industry to a halt.
I had these discussions with Ergon and Energex on behalf of several Chinese inverter manufacturers over 10 years ago.
…it’s a bit like “stone soup” in reverse. A long time ago I asked if some wunderkind could modify a grid inverter so it could run independently? Know a thing or two about what’s involved, but find that no one wants to try it. (The suggestion to connect the inverter connected to the battery to the “mains input” may work.) Will this work?
”The inverter must operate at a higher voltage than the grid so that it can export electricity (current flows from a higher voltage point to a lower voltage point, not vice versa).”
Well, the above is true if we have a DC grid. But AC is a little more difficult. Simply increasing the voltage doesn’t really do anything to increase power flow. In fact, what we need to do is try to increase the frequency of the inverter. But in the end, when we turn off the power from the inverter, the first principles will see the voltage increase.
No, it’s not difficult. Like direct current, alternating current only flows from high voltage to low voltage…end of story. The magnitude of the voltage difference and the link impedance directly determine the amount of power flowing (or more precisely, the power that the inverter wants to output and the link impedance determine the voltage that the inverter must supply for export). , electricity). This is why “boosting” the voltage is a problem, as this boost usually causes voltage problems in the inverter, and sometimes in some cases the voltage at the grid connection point may be within specification, so the installer must perform a voltage test. The rise is calculated and, if necessary, maintained within specification by increasing the wire size to the house. Frequency does not appear anywhere in the equations.
I think when you talk about frequency, you add 1 and 1 together to get 11. Yes, frequency is important for network management. Usually, when the network is overloaded, the frequency tends to rise, and when the power supply is insufficient, the frequency tends to fall. This mechanism is used in inverters to limit power when something is out of range, this “inertia” from the rotating generator helps to keep the balance. But this has nothing to do with the flow of energy. Our grid inverters (and all the generators on the grid) actually have to match the grid frequency as the grid oscillates.
Not really. Changing the voltage on the AC generating equipment changes the output reactive power. This may be to or from the production device. This is a way to control the reactive power of all generators, including inverters. For those states that need to be fed with a hysteresis of 0.8 PF (from memory), this is achieved by varying the voltage. This exacerbates the VD problem because any change in the unified power factor will increase the current and therefore VD.
Active power flow is increased by “trying” to increase the frequency. On conventional generators, this is achieved by opening the control valve. On a grid inverter, it’s a bunch of electronics.
Sorry, it seems to me that adding 1 and 1 and 1 and 1 together gives 1111, which I think further confuses a relatively simple question, but is half true. Although it is clear that you understand something, it seems to me that this is a case of not understanding what you have learned. I find your logic flawed and probably too complicated to go into. But you speak with authority, and if backed up by real knowledge and experience, I always seek to learn from people who may know what I do not know, and not risk continuing to live in an ignorant world. wrong. Perhaps the accepted laws of physics have changed, and you can tell me about some new development that changes everything. After all, I got my degree in electrical engineering 30 years ago, and I’ve never actually built generators or inverters and don’t claim to be an expert in power transmission or generation, so that’s not my area. examination . But I have a reasonable understanding of things, and perhaps more importantly, I lean towards the fundamentals that drive it. But maybe something fundamental has changed that makes most of the basics wrong (probably unlikely)… or more likely I was too drunk and if so I’m not so happy to listen to this lecture, so I’m glad I got corrected.
But the reality is that the laws of physics, electrical currents, and energy flows don’t pander to the guesswork of a bunch of pretentious internet experts (myself included). They are governed by tried and tested mathematical principles. So, if what you’re saying is true, can you please point me to any documentation or equations that back up what you’re saying so I can learn.
All AC is more complicated than DC, which is actually half true. But the reality is that if you look at any short enough period, it’s exactly the same, and we probably don’t need to confuse electrical engineers with complexity. The only difference that makes this a little more difficult is that capacitors and inductance introduce some factors which means we have to account for them, meaning that voltage and current are always changing, not necessarily in stationary DC as they are. would be synchronized in the circuit (more precisely, they are synchronized with each other, but can be phase-shifted, so the current lags or leads the voltage, which affects the CM). But they do not fundamentally change the simple principle that power always flows from high voltage to low voltage. As long as the two AC power supplies are in a state of voltage synchronization as required by the grid, voltage will always flow from high voltage to low voltage. Voltage. Period, end of story. Nobody needs to read further if you don’t believe in this very simple principle.
Post time: Jun-06-2023