how do I combine two separate votages from two different generator sources?

Question

I know how the step up or down transformer works or even a voltage divider. Would one us the same kind of transformer to combine a voltage from for example a alternative fuel generator and a wind mill to achieve suitable household voltage. possibly the ability to wire utility company source voltage so that it is the last resort for use when operating several energy generating sources? (note I am not trying this at home!)

Answer 1

You would need to match the frequency and the timing (phase) of the two different generators. It can be done manually, and there are types of automated systems out there which do the same. This article can explain it better than I can.

Answer 2

Yes, it is, but it is not something to experiment with. In the case of an offline connection (don't let the term confuse you, "offline" doesn't mean "not ON the line", it means "power taken directly off the line") it is accomplished by controlling current flow, not voltage.

What you propose is possible; your alternative power source and power from the grid could be connected to poles of an electronic relay with the common relay contacts connected to the load side of your home. In this way, there is never any connection between the grid and your alternative power source(s). The relay could be controlled by monitoring the supply voltage of your alternative source, and whenever it drops to some threshould, perhaps 90%, the relay switches back to the grid. But then when do you switch back to your alternate? Once unload, the voltage will instantly rise back up, even though it would drop again the instant you switched back.

Therefore the ideal way to accomplish this is via current control, and current control of AC voltage is a bit tricky. Where I work, we make high-power electronic loads. We also make high-power battery chargers, the type you would use to recharge a 1-ton battery pack for a forklift. We use the loads to simulate a battery pack for the testing of the chargers. Both the loads and the chargers are supplied by heavy 3-phase to the grid. And what the loads do, when a charger is hooked to them, is converted the 500 amp 80 volt
dc from the charger into an AC current that is fed back into the grid proportional to the instantaneous voltage. It's tricky, but the result is that, even tho the charger is a load of say 40kW, the load puts up to about 35 of those kilowatts back into the line, net result that we're only drawing 5kW. But like I said, it's tricky.

I'm confident that there are commercially available devices that can do what you ask for that would work similarly, i.e., they would always keep you alternative source connected in, yet at the same time, draw power from the grid only as needed. power companys have been doing this for years - virtually thousands of sources are connected together nationwide to the same grid. I'll see if I can google up something later, I'm a little interested in this myself. Watch for a repost.

Answer 3

To combine sources, it is necessary to match the voltages and synchronize the frequencies and phase relationship of the waveforms. That can be done with an inverter that has the ability to either receive or supply power. The sources can then be connected in parallel. There are also safety requirements and utility regulations that must be complied with. There are products that are specifically designed to meet all of the requirements. There are technicians that are trained to help you select the products and install them for you.

Answer 4

Most simply use an inverter or UPS setup with a secondary charger.