How To Choose A Hydro Transformer?

As we all know, in the design of hydropower station, the hydro transformer should generally choose a step-up transformer, that is, the voltage of the boosted voltage side is 10% higher than the rated voltage of the voltage level.

Such as 110kv hydro transformer, 35kV transformer should be 121kV, 38.5kV, etc., the purpose is to make the sending terminal voltage of the hydropower station balance with the system receiving terminal voltage after the loss of the line voltage, so as to ensure that the generator set operates at the rated voltage.

However, there is no formal step-up transformer in the 10kV voltage level hydro transformer stereotyped products, but only distribution hydro transformer with a voltage of 10±5% kV.

This step-up transformer is used in rural small hydropower stations.

Especially the hydropower station with long transmission distance and large line voltage loss. However, the use of such a step-up transformer often causes the problem of excessively high output voltage and insufficient reactive power at the generator outlet.

Therefore it is unreasonable.

According to this situation, Vintec’s designer specially designed a 11±5% kV step-up transformer to solve this problem well.

At the same time, Vintec also has a professional installation team in North America, which can provide you with professional after-sales service.

Vintec’s hydro transformer have obtained IEEE, CSA, ANSI, DOE, IEC and other certifications, as well as a number of patented inventions, which can ensure the quality of the hydro transformers you purchase and provide you with high-quality products.

Small hydropower stations are the most suitable for the selection of step-up transformers.

The following author will explain the reasons for choosing a step-up hydro transformer from two aspects.

Operate independently

This method of operation is relatively common.

Its operating characteristics are: the load distribution is far and scattered, the load time is relatively concentrated and varies greatly, when the power station supplies power, there is no other power supply on the network, and the voltage of the entire network is controlled by the machine terminal.

Part of the 400V power generated by the generator is directly supplied to nearby users, and part of it is boosted by a 10000/400V hydro transformer for long-distance transmission.

It is then stepped down by a hydro transformer of the same level and supplied to remote users.

It is obvious that the voltage that meets the requirements cannot be obtained after several losses and line losses.

Due to the limited range of the transformer no-load adjustment switch. If the user voltage is to meet the requirements, it can only be satisfied by increasing the speed of the unit and increasing the excitation current, which artificially increases the terminal voltage of the unit and makes the unit run in a state of over-rated voltage.

This will cause the temperature of the unit to rise, accelerate the aging of the transformer, and seriously affect the life of the generator.

The operating characteristics are: the load is relatively stable, the inrush current of the large load is borne by the power grid, and the small hydropower station can only obey the power grid to transmit a certain amount of electric energy.

When operating on the Internet, the grid connection point is in a hydropower station, and when the voltage sent from the network at the front end of the grid connection point is higher than the rated voltage of the generator, in order to achieve synchronization, the generator voltage will also increase, artificially increasing the generator no-load. Excitation current, and has a great impact on the measurement and assessment of reactive power during operation (under-generating reactive power is often subject to economic penalties).

When the unit is running at full load, if the entire load on the network decreases (low, flat valley period), the grid voltage and frequency will increase, and the machine terminal voltage will increase accordingly. If the excitation is not increased, the reactive power will be insufficient;

If the excitation is increased, the excitation current of the generator will exceed the rated excitation current, and the unit will run in the state of over-rated voltage for a long time, and the result is the same as the above.

To sum up, the hydro transformer used for step-up in the hydropower station should be carefully selected in the design. If you cannot choose a step-down transformer, you must choose a step-up hydro transformer according to the technical requirements, so as to avoid the economic loss caused by the premature aging of the unit and the lack of reactive power.