Autonomous power supply systems of a private house

We continue the series of articles on the topic autonomous power supply for a private house.

In previous articles, we have already considered several types autonomous sources of electricity, namely: Uninterruptible power supplieswhere batteries are the source of electricity, and diesel, gas or gas generating sets are the second source of energy.

The advantages and disadvantages of each of the devices we examined, as far as possible in words, is quite extensive, in this same article we will try to figure out how to combine both of these devices, to use the full potential of both the generator set and the uninterruptible power supply to the maximum.

For a more complete picture of the upcoming event, I would like to note the relatively high cost of the entire set of equipment that will have to provide electricity to your home.

So, a good mini-power plant with a capacity of 5-6 kW will cost you about 2-2.5 thousand dollars. In this price category you can buy, for example, a HONDA generator equipped with an electric starter.

UPS in kit c helium batteries, designed for 3-4 kW will cost you about the amount of 1.5 to 3 thousand dollars. Why such a runaway in price, you will understand a little later. UPS prices can fluctuate both up and down. It all depends on the manufacturer, the quantity and capacity of the battery.

After conducting simple arithmetic calculations, we get an amount of about 4-5 thousand US dollars. Plus, this amount will need to add the cost of additional equipment and the cost of electrical work.

But in this article we will not consider what it costs, the purpose of this article is slightly different, namely, to consider the feasibility of the whole complex as a whole, what and how best to do so that it is both practical and inexpensive, in terms of further operation.

Further, what else do we need ...

Most mini-power plants are not equipped with an autostart system, that is, a device that will control the process of starting and stopping the generator when the main electricity is turned off. For these purposes, we need ABP-automatic backup power.

How ATS works, we will not consider its algorithm of work in this article, this is another article.

Tip number 1.

Generator sets of medium and low power, namely such we use in everyday life, do not always produce high-quality voltage, in terms of frequency and sinusoid. It is to these parameters that many UPSs are very sensitive. UPSs perceive this as an accident on the line and go into protection, that is, they turn off or do not see the input voltage.

To avoid further problems in the operation of the entire energy complex, we recommend that you choose a UPS from the online series. Most online UPSs are omnivorous, that is, they are not so demanding on the input voltage, frequency and sinusoid. The output of such devices is always a stable voltage with a pure sinusoid, to which many modern electrical appliances are so sensitive.

Tip number 2.

Before starting all work, you should clearly know what exactly you want to get in the end result. To make it clearer what we are talking about, let's look at the situation with power outages, how the equipment should work, and, based on this, we will develop an algorithm for the entire system.

So, situation number 1. The operation algorithm of the equipment is approximately the following:

1) Shutdown of the main electricity;

2) The load is transferred to the UPS for a certain time “N”;

3) The generator station starts up;

4) The load is switched to the generator, while the UPS batteries are being charged;

5) The main (city) electricity has appeared, the load is switched to the city, the generator is turned off.

In this case, we have a strictly specified time “N”, during which the generator must start and, accordingly, the UPS must provide consumers with electricity strictly specified time “N”.

Accordingly, knowing the load power and the required operating time from the UPS, it is easy to calculate the battery capacity. How to do this is described in detail. in the previous article.

In this situation, we will significantly save on the cost of the battery, as in this case, you can do with small batteries. But we lose in another place, namely, in fuel, since the generator will start regardless of whether it is needed at the moment or not.

To avoid unnecessary generator operation, consider another situation.

Situation number 2. The equipment operation algorithm (UPS + generator) will be approximately as follows:

1) There was a shutdown of the main electricity;

2) The load transfers to the UPS for an UNCERTAIN TIME “N”. In this case, the time “N” will depend on how much the UPS will be loaded at the moment and, accordingly, how long the battery will last.

3) If the main (city) electricity did not appear and the UPS is no longer able to support consumers ...

4) The genset starts up;

5) The load switches to the generator, while the UPS batteries are charging.

6) When urban (main) electricity appears, the load goes to the network, the generator stops.

As can be seen from the example, in this case, the generator does not start until the UPS or any other additional device sends a command to start the generator.

The UPS itself can give a command to start the generator, the benefit is that in many modern UPSs there is such a function, that is, initially the manufacturer provides for the joint operation of the UPS and the generator.

If the UPS does not have such an opportunity, there are a lot of voltage controllers for upper and lower limits, which can easily be supplemented with any UPS.

Such a schematic solution (No. 2) is much more profitable than the previous one, since there is no idle operation of the generator. But, in this case, the system will cost an order of magnitude more expensive, since long-term operation of the UPS will require batteries of significant capacity.

But, in any case, no matter what decision you make, installing an autonomous power supply system is a relatively difficult task, the implementation of which is best left to professionals.

Sergey Seromashenko