What is the difference between an excitation transformer and a distribution transformer

The excitation transformer is only used in power plants and is the core equipment of the excitation system of power plants. After the excitation transformer, the thyristor is passed.

The three-phase power supply is converted into the DC power supply of the generator rotor to form the generator excitation magnetic field; The mechanical torque obtained by water flow, steam, etc., pushes the rotor that is the rotor DC magnetic field to rotate, forming a rotating magnetic field to cut the stator coil, and generating an induced electric field in the stator coil.

and currents; The stator coil is fed out, and after synchronization, it is connected to the grid for power generation.

Distribution transformer refers to the substation equipment that is usually used in the electricity client to distribute electric energy or supply electrical energy to electrical equipment. In a broad sense, it refers to transformers below 110kV that are different from power generation and transmission transformers (power plants and transmission links), mainly step-down transformers (also including step-up transformers for special applications, which are connected to electrical equipment at the near end). In a narrow sense, it refers to a 20kV or 10kV step-down transformer.

The voltage on the low voltage side of the excitation transformer is designed according to the excitation voltage, which is a non-standard voltage; The low-voltage side of the distribution transformer is 400 230V standard voltage. The distribution transformer has a tap-changer for adjusting the voltage on the high-voltage side, while the excitation transformer generally does not have a tap-changer. The excitation transformer considers the harmonic component of the silicon rectifier more, and the magnetic circuit design is different from that of the distribution transformer.

The excitation transformer is mostly a dry-type transformer, while the distribution transformer is mostly oil-immersed.

1. The excitation transformer capacity is much larger than that of a general distribution transformer.

2. The excitation transformer is generally a dry-type transformer, and there are many power distribution transformers.

3. In terms of protection configuration, the excitation transformer generally has a special differential protection, and the distribution transformer capacity is not enough, so it is generally not done.

4. The installation position of the excitation transformer is at the outlet of the generator, and the distribution transformer is on the power supply line.

5. The excitation transformer provides more reactive power, and the distribution transformer generally provides active load.

Let's write so much first, and write when you remember.

The excitation transformer is a device that provides three-phase AC excitation power supply for the generator excitation system, and the excitation system converts the three-phase power supply into the DC power supply of the generator rotor through the thyristor, forming the generator excitation magnetic field, and adjusting the thyristor trigger angle through the excitation system to achieve the purpose of adjusting the motor terminal voltage and reactive power. It is usually connected to the generator outlet end, because the generator outlet voltage is high, and the rated voltage of the excitation system is low, so a step-down transformer is required.

The safe and stable operation of the excitation transformer for the generator is the prerequisite for the safe and stable operation of the self-parallel excitation unit, the prerequisite for the stable power generation and full load power generation of the generator set, and the key to the reliable operation of the excitation system.

As we all know, the distribution transformer is specially designed to provide the required voltage for electrical equipment and users, and there are two forms: step-up and step-down.

A transformer is a relatively stationary electrical device consisting of two or more windings wound around the same core, and the windings are connected to each other by alternating magnetic fluxes. Power transformers are used for the economical transmission, rational distribution and safe use of the electrical energy generated by power plants.

The working principle of the transformer is "electricity generates magnetism, and magnetism generates electricity". The primary (primary) coil and the secondary (secondary) coil of the transformer are wound together on an iron core, when the primary coil is passed through the voltage U1, an alternating magnetic flux is generated in the iron core, and this magnetic flux passes through the primary and secondary windings, and according to the law of electromagnetic induction, the induced electric potentials E1 and E2 are generated in the primary and secondary windings respectively.

According to the law of electromagnetic induction, the induced potentials of the primary and secondary windings are: e1 e2=u1 u2=n1 n2=k (k is the transformation ratio).

Classification is classified by cooling method: dry-type (self-cooled) transformer, oil-immersed (self-cooled) transformer, fluoride (evaporative cooling) transformer.

Classified according to moisture-proof methods: open transformers, potted transformers, sealed transformers.

Classified according to the structure of iron core or coil: core transformer (insert core, C-type core, ferrite core), shell transformer (insert core, C-core, ferrite core), ring transformer, metal foil transformer.

The transformer is a static electrical that converts voltage and current, and its main role is to transform voltage.

Hello, I would like to ask, you are asking about the excitation of the generator.

Transformers? Generally our power system.

The excitation system is now generally self-exciting. If you are talking about the excitation change of the generator in our power system, then the power supply of this excitation transformer is taken from the electricity emitted by the generator itself.

Because there is remanence in the core of the generator, after the generator rotates, an electromotive force is generated.

A magnetic field is generated, which is continuously strengthened to meet the requirements of the power plant, and the electricity generated in this process is also continuously sent to the excitation transformer for use in the excitation system.

1.Improve the ability of the power system to operate stably, no matter what disturbance the power system is, by adjusting the excitation of the synchronous motor, the ability of the system to operate stably has been improved. When the power system is subject to small or large disturbances, resulting in a small or large speed change state of the synchronous motor, the static stability or dynamic stability or transient stability will be adversely affected.

In this case, the excitation control will suppress or eliminate this effect, and keep the synchronization of the synchronous motor stable. 2.The relationship between the internal potential eq of the generator and the voltage at the generator terminal u, the load current i of the generator and the reactance x of the generator to maintain the voltage level of the power system can be expressed by the following formula:

eq=u+ jix Note: eq, u, i are vectors When the load of the power grid increases, that is, the generator current i increases. As can be seen from the formula, if the EQ does not change, the voltage u at the generator end decreases.

If an excitation regulator is installed, the excitation current (i.e., rotor current) can increase with the increase of load, that is, the EQ increases to maintain the generator terminal voltage U at a certain level. On the contrary, after the generator is shedding, the automatic excitation regulator can reduce the excitation current in time to limit the voltage at the end of the generator from rising excessively. The excitation of the generator can be automatically adjusted to keep the reactive power or power factor of the power supply system constant.

Constant voltage is an important indicator of the quality of power supply. 3.Improve the power limit of the generator and the ability of the power system to transmit power4

Improve the operating state of the power system and synchronous generators: improve the reliability of relay protection devices; When a short-circuit fault occurs in the system, the short-circuit current is attenuated very slowly or even not at all by adjusting the excitation (strong excitation). This ensures that the short-circuit current enables the relay protection device to operate accurately and reliably at the setting value and time.

Balance the reactive power between each generator during grid-connected operation, so that it can reasonably share the reactive power required by the system; 。When the system short-circuit fault is eliminated, the excitation is automatically adjusted to speed up the system voltage recovery; By controlling the excitation, in addition to maintaining the constant voltage operation of the synchronous generator, the system can also be operated as constant reactive power or constant power factor, so as to improve the economy of power system operation. 5.

The excitation regulator of the synchronous motor should also meet the following requirements: It can adapt to the synchronous motor in different stages of the "starting", "excitation" and "leading synchronization" process, and automatically adjust the excitation on demand; When the synchronous motor or condenser compensates the system for reactive power, the excitation should be adjusted so that the motor has a good reactive power compensation effect and a certain phase advancement ability for the system; Depending on the nature of the mechanical load and the severity of the load, the excitation regulator should have a flexible operation mode to ensure the energy saving of the power supply system. Effect.

The excitation transformer is a device that provides three-phase AC excitation power supply for the generator excitation system, and the excitation system converts the three-phase power supply into the DC power supply of the generator rotor through the thyristor, forming the generator excitation magnetic field, and adjusting the thyristor trigger angle through the excitation system to achieve the purpose of adjusting the motor terminal voltage and reactive power.