The difference between a high voltage generator set and a low voltage generator set

The difference between the parameters and performance of high-voltage generator sets and low-voltage generator sets is mainly reflected in the generator part and the distribution system part.

1 Difference in volume and weight.

High-voltage generator sets use high-voltage generators, and the increase of voltage level makes its insulation requirements higher, correspondingly, the volume and weight of the generator part are larger than those of low-voltage units. Therefore, the volume and weight of the overall fuselage of the 10kV generator set are slightly larger than those of the low-voltage unit. There is no big difference in appearance except for a slight difference in the generator part.

2 Differences in grounding forms.

The neutral grounding method of the two generator sets is different. The winding of the 380V unit is a star-shaped wire, and the general low-voltage system is a neutral direct grounding system, so the star-shaped wiring neutral point of the generator is set to a withdrawable type, which can be directly grounded when it needs to be used. The 10kV system is a low-current grounding system, and the neutral point is generally not grounded or grounded through the grounding resistance.

Therefore, compared with low-voltage units, 10kV units need to add neutral point distribution equipment such as resistance cabinets and contactor cabinets.

3 Differences in protection methods.

High-voltage generator sets are generally required to be equipped with current quick break protection, overload protection, grounding protection, etc. When the sensitivity of the current quick break protection does not meet the requirements, the longitudinal differential protection can be installed.

When a grounding fault occurs in the operation of the high-voltage generator set, it will cause great safety hazards to people and equipment, so it is necessary to set up grounding fault protection.

The neutral point of the generator is grounded by resistance, and when a single-phase grounding fault occurs, the fault current flowing through the neutral point can be detected, and the trip or shutdown protection can be realized through relay protection. The neutral point of the generator is grounded by resistance, which limits the fault current to the allowable damage curve of the generator, and the generator can operate with faults. Through the grounding resistor, the grounding fault can be effectively detected and the relay protection action can be driven.

Compared with low-voltage units, high-voltage generator sets need to add neutral point distribution equipment such as resistance cabinets and contactor cabinets.

The high-voltage generator set needs to be equipped with differential protection if necessary.

Three-phase current differential protection is provided on the stator windings of the generator. Through the current transformer installed at the two outlet ends of each group of coils of the generator, the current difference between the inlet and outlet ends of the coil is measured to judge the coil insulation. When any two or three phases are short-circuited or grounded, fault currents can be detected in both transformers to drive protection.

The main difference between high-voltage generator set and low-voltage generator set is that the voltage is different, and the general low-voltage generator refers to the general 230V 400V generator set on the market. The motor part of the high-voltage diesel generator is customized according to the customer's requirements, generally 10kv,! The differences are as follows:

1.Aging delay: The low-voltage current is 26 times that of the high-voltage, the heat load loss is greatly increased, and the equipment is easily damaged.

2.High anti-harmonic ability: due to the design, structure, process and other aspects of the generator, the anti-harmonic ability of low-voltage generator sets is lower than that of high-voltage generators; Due to the power supply of the high-pressure oil turbine through the transformer, the transformer has a partial elimination effect on harmonics, and the neutral grounding of the high-pressure oil engine also has a partial elimination effect on the system harmonics.

The overall high-pressure oil press has a stronger capacity with non-linear load than the oil press.

3.Low risk coefficient of non-synchronous short circuit: When multiple low-voltage generators are supplied in non-parallel power, there is a risk of non-synchronous short circuit due to the non-synchronization of each power supply system.

4.High safety: Due to the excessive current, the arc extinguishing of the output circuit breaker of the low-voltage unit is not as good as the high voltage, and it is often damaged due to arc pulling.

5.Centralized power supply: Low-voltage generators cannot achieve long-distance power supply due to large heat loss due to the large use of cables.

The high-voltage generator set has the advantages of high voltage regulation accuracy, good dynamic performance, small voltage waveform distortion, high efficiency and long service life, which is quite popular with users and has been widely used!

Generators with the same power and cycle rate, compared with high-voltage generators and low-voltage generators, the number of coil turns is multi-turned, the wire diameter is thin, and the output current is small.

This one** is also available.

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The high-voltage generator set has the advantages of long output distance and small loss, and the large-scale data disturbance center in the fields of finance, insurance, communications, education and filial piety can be used as a standby generator set, which plays a pivotal role. Hope it helps.

I will help you answer the question of how to distinguish between high and low voltage of hydro turbine generators. Generally speaking, high voltage usually refers to power equipment with a rated voltage of 10kV and above, and low voltage usually refers to power equipment with a rated voltage of 1000V and below. Specifically, the high-voltage end of the hydro-generator refers to the end that outputs high voltage, which is usually connected to the substation or transmission grid, and the voltage is raised through equipment such as transformers to transmit electric energy to users or other transmission equipment over a longer distance; The low-voltage end is usually the one that outputs the low-voltage end and is responsible for supplying power to other parts of the power equipment or to parts of the power equipment.

It should be noted that the definition of high voltage and low voltage is usually related to different countries or regions, different applications, and different factors such as the structure and scale of the power system, so it is necessary to consider and judge according to the actual situation when using and designing hydrogenerators.

The rapid development of large-scale data centers, coal mining enterprises, etc., has driven the demand for high-voltage generator sets. Generally speaking, the high-voltage generator sets we call are mainly divided into two types: 6 kV and 10 kV. High-voltage generator sets use high-voltage generators, and the increase of voltage level makes their insulation requirements higher.

Generally, high-voltage generator sets need to be equipped with high-voltage cabinets, and low-voltage generator sets are ordinary distribution cabinets, and the styles are as follows:

The difference between high-pressure diesel generator set and low-voltage diesel generator set is shown in the figure below

When the voltage is high, the impact on the generator set is as follows:

1.The temperature of the rotor surface and rotor windings increases. When the generator runs at twice the rated voltage, the rotor surface heats up, which in turn causes the temperature of the rotor windings to rise.

It is mainly due to the increase in the leakage flux and the increase in the higher harmonic flux due to the increase in additional losses. Theoretically, the heat of the core loss is proportional to the square of the voltage, so the higher the voltage, the faster this loss increases, which heats up the rotor and increases the temperature of the rotor windings, which may exceed the allowable value.

2.The stator core temperature increases. The heating of the iron core is determined by two factors, one is caused by the loss of the iron core itself, and the other is the transmission of the stator winding temperature to the iron core.

When the voltage increases, the magnetic flux density in the core increases, and the loss also increases, because the loss is approximately proportional to the square of the magnetic flux, so the increase of the magnetic flux causes the loss to increase rapidly. In addition, the relative utilization rate of the core of the large-capacity unit is high, and the magnetic flux is closer to saturation, so that the change of loss caused by the increase of voltage will increase more obviously. So the voltage is high, the core loss will rise greatly, and the temperature will increase greatly.

Under normal circumstances, if the high voltage in the operation of the system does not exceed 10% of the rated voltage, the threat of core heating is not significant.

3.The structural components of the stator may experience localized high temperatures. The voltage is high, the magnetic flux density increases, and the saturation of the iron core intensifies, so that more magnetic flux escapes out of the yoke and passes through some structural components, such as support ribs, machine bases, tooth pressure plates, etc., forming another loop, so that eddy currents are generated in the structural components, which may cause local high temperatures.

4.Threatens stator winding insulation. Under normal circumstances, the generator can withstand times the rated voltage. However, for generators that have been running for many years and the insulation has been aged, or there are latent insulation defects, it is easy to cause insulation breakdown accidents.

When the generator voltage is too high, it will burn the distribution screen to protect the instrument meter, and it may also break down the insulation of the generator winding.