This would be fantastic. I'm trying to write an audio driver for my HT|Omega eClaro PCIe soundcard for Linux by leveraging kernel modules for cards with a similar BOM. It is mostly working, but the main hurdle is the inability to increase the volume to >= 50% of the volume in Windows. I'm setting attenuation correctly to the correct DAC registers and I can hear the opamp relay click on, but can't adjust the final gain. It sure would be great to have the Windows driver source. Worse yet, the company is unresponsive to my requests for any info (schematics, gain setting sequence, anything).
The PE6000 and the LM6000 are two shaft machines, where there is a low speed shaft on which sits the low pressure compressor and low pressure turbine (the hot and cold ends), and a high speed shaft on which sits the high pressure compressor and high pressure turbine. The two shafts are concentrically located, with the high speed shaft being on the outside. The low speed shaft is where the generator is coupled, and can be done on either the hot or cold end.
You're right that the core doesn't spin at synchronous speed but the LP shaft does. It's optimized for 3600rpm, but could run at other speeds... the machine just isn't designed for it. The LM6000 only uses a gearbox for 50Hz units while 60Hz don't need it.
The LM6000 and its variants have been in operation since probably the 1980s. I can ask around at work. I used to develop the code for the LM6000.
You're spot on that people use them for peaking, but it's a big mix. Peaking, mid-merit, and sometimes base load. There are low emissions versions as well, that keep NOx to a handful of ppm without using extra water.
People tend to use the inertia H constant (MW*s/MVA) when it comes to describing the amount of inertia that grid forming inverters and batteries can provide. Sometimes the units are simplified to seconds, which makes it easier to understand how many seconds it could provide rated power for this specific function.
Active inertia or synthetic inertia do vary power when frequency changes but the key is the dynamic behavior. They typically do so by emulating a synchronous machine by implementing something like the swing equation in the active power control (see REGFM_B1 [1]). They essentially emulate the inertia, which makes them have some damping in changing the phase angle and frequency of their voltage waveform just like a spinning synchronous generator would when resisting frequency changes due to physical inertia, resulting in an inertial active power response. This makes it easier for people to analyze because they understand the swing equation from synchronous generators.
A machine with infinite inertia would resist any frequency change and instantly go to maximum or minimum power upon any grid frequency deviation.
A 25s inertia constant is impressive. The hydro units I work on are anywhere from 1s for newer units to 7s for older ones intended to run isolated networks. And then the ease of frequency regulation on the unit is dictated by the inertia of the water in the water conveyance system “water starting time”
So 25s inertia constant would appear to be a response to frequency change much faster and greater than the typical 5% droop implemented by the governors controlling mechanical power applied to the shaft.
Would you mind sharing any pictures or video about the mower? I converted my push reel to electric without a kit, and have been considering putting separate high torque, low speed motors for drive wheel control to start moving towards autonomous cutting. Would be great to see your experience!
I made it for my country home and won’t be there for a bit but maybe one day I’ll document it. But the parts store I used closed down, Open Builds Part Store. It’s nothing proprietary to them, I just got all the v slot aluminum frame and connectors there to build the chassis. Then I got hub motor wheels on Amazon or Aliexpress and batteries too. Most small components I get on Amazon, motor controller. I went with off-road air filled tires. And I wrote all then logic into an arduino mega. Oh and I used an upside down rubber made container as the case for electronics. Everything is mounted to the bottom of the lid and the box part is functionally the lid that I remove to gain access. It as built in snap locks and I used weather stripping to make the seal tight.
You just have to figure out how to mount to the lawn mower part of your choice, after than it’s the same as building any vehicle.
Yeah sorry to make it sound easy. I learned all this on YouTube and tailored those lessons to my needs, so just a nod to the fact that tons of much better resources already exist. I have no official training, if a finance bro like me can figure it out I have a lot of hope for anyone else on HN :)
Granted I have built a few robots prior to this one as a hobby hacker, so this one felt pretty easy for me. If it’s your first, it will probably take you 6 months LOL. In almost all cases, you’re better off buying unless you just like the maker aspect of the project, which was true for me.
Gas plants can change load in seconds by increasing or decreasing fuel flow. You can consider the generators as operating at the local grid frequency, and power being the product of torque and frequency, so they just change torque to change load, which is done through fuel control. Aeroderivative gas turbines can go from near 0 to full load in less than 30 seconds, which is obviously an eternity compared to battery system inverters with sub 150ms settling times.
You are right that load isn’t independent of frequency, though. For those who are interested, in a simplistic and hand-wavy explanation, the torque imbalance between generation and load causes a change to the frequency. The net torque = torque of generation - torque of load = I*alpha, where alpha is the derivative of omega, or the angular frequency of the grid, and I is analogous to the inertia of the grid. If there is more generation torque than load torque on a generator (and the grid), the frequency increases and vice versa. Keeping the net torque constant, increasing the inertia makes the grid frequency derivative smaller for the same imbalance between generation and load, which is why it was typically desirable to have higher inertia synchronous generators.
What you were describing around changing fuel to maintain speed is typically frequency droop, which is where generators change their power as a function of the frequency, which is a distributed scheme for all generators to independently act to drive the torque imbalance to 0, with some insensitivity proportionality constant. For example, in California, gas turbines are assigned a droop value within the range of 3 to 5%, which means a 3 to 5 % reduction in frequency should result in a 100% increase in power, and vice versa. The total power should be provided in less than 30 sec typically.
For those that are really motivated to understand the interplay between generation, load, and frequency, look up the swing equation in the context of power system stability.
There is another aspect of synchronous generators that enable them to act to stabilize frequency independently, called the inertial response, which also has to do with their rotational energy. A generator at some frequency has KE = 0.5*J*omega^2 where J is rotational inertia and omega is angular frequency. If the frequency changes, it has a change in kinetic energy = 0.5*J*(omega1^2 - omega2^2) which is equal to some power for some period of time (= P*delta_t). This shows that as a generator sees a change in frequency, the shorter the duration, the larger the amount of energy is converted to power. Essentially, generators have an inertial response that act to inject power the faster frequency is falling, and vice versa, which is a self stabilizing function for grid frequency.
This loss of synchronous inertia as generators are replaced by inverter based resources (IBRs) is why managing grid frequency stability becomes more difficult. Various techniques are used to abate the loss of inertia, including emulating the swing equation within inverters to make them behave as synchronous generators and provide that inertial response. This is typically called grid forming with virtual synchronous machine.
There's no mention of the actual electrical architecture. In the rendering, I only see modules and no DC/DC converters or inverters separate from the modules. Some of the competition uses module level inverters so maybe that's their approach as well? It's hard to tell if the 3 large conductor looking objects going down the font of the module faces (or rear?) are 3 phase AC or 2 x DC cabling + 1 comms or a fire suppressant line.
It would also be good to know what depth of discharge nets them 12,000 cycles (edit: looks like 95%)
I design control systems for grid scale battery systems that can operate as standalone power plants, or as hybrid power plants with solar, wind, or gas turbines.
Batteries essentially enable planners to increase renewable generation and make it less variable.
For gas plants, they can avoid or reduce the need to run gas turbines as peaking power plants which are typically needed to cover the significant gap between renewable generation and residential loads in the early evenings. The batteries can cover that period with energy shifted from the day to the late afternoons and early evenings.
Of course there is still CO2 emitted in their manufacturing, but I am coming from a previous career in making gas turbine control systems, so it's still an improvement. I'm trying to make the broadest impact I can as an engineer.
