A generator set generally consists of an engine, generator, comprehensive control system, oil circuit system, and power distribution system. The power part of the generator set in the communication system – diesel engine or gas turbine engine – is basically the same for high-pressure and low-pressure units; The configuration and fuel volume of the oil system are mainly related to power, so there is no significant difference between high and low pressure units, so there is no difference in the requirements for the air intake and exhaust systems of the units that provide cooling. The differences in parameters and performance between high-voltage generator sets and low-voltage generator sets are mainly reflected in the generator part and distribution system part.
1. Differences in volume and weight
High voltage generator sets use high-voltage generators, and the increase in voltage level makes their insulation requirements higher. Correspondingly, the volume and weight of the generator part are larger than those of low-voltage units. Therefore, the overall body volume and weight of a 10kV generator set are slightly larger than those of a low-voltage unit. There is no significant difference in appearance except for the generator part.
2. Differences in grounding methods
The neutral grounding methods of the two generator sets are different. The 380V unit winding is star connected. Generally, the low-voltage system is a neutral point direct earthing system, so the star connected neutral point of the generator is set to be withdrawable and can be directly grounded when needed. 10kV system is a small current earthing system, and the neutral point is generally not grounded or grounded through grounding resistance. Therefore, compared to low-voltage units, 10kV units require the addition of neutral point distribution equipment such as resistance cabinets and contactor cabinets.
3. Differences in protection methods
High voltage generator sets generally require the installation of current quick break protection, overload protection, grounding protection, etc. When the sensitivity of current quick break protection does not meet the requirements, longitudinal differential protection can be installed.
When a grounding fault occurs in the operation of a high-voltage generator set, it poses a significant safety hazard to personnel and equipment, so it is necessary to set up grounding fault protection.
The neutral point of the generator is grounded through a resistor. When a single-phase grounding fault occurs, the fault current flowing through the neutral point can be detected, and tripping or shutdown protection can be achieved through relay protection. The neutral point of the generator is grounded through a resistor, which can limit the fault current within the allowable damage curve of the generator, and the generator can operate with faults. Through grounding resistance, grounding faults can be effectively detected and relay protection actions can be driven. Compared to low-voltage units, high-voltage generator sets require the addition of neutral point distribution equipment such as resistance cabinets and contactor cabinets.
If necessary, differential protection should be installed for high-voltage generator sets.
Provide three-phase current differential protection on the stator winding of the generator. By installing current transformers at the two outgoing terminals of each coil in the generator, the current difference between the incoming and outgoing terminals of the coil is measured to determine the insulation condition of the coil. When a short circuit or grounding occurs in any two or three phases, fault current can be detected in both transformers, thereby driving protection.
4. Differences in output cables
Under the same capacity level, the outlet cable diameter of high-voltage units is much smaller than that of low-voltage units, so the space occupation requirements for outlet channels are lower.
5. Differences in Unit Control Systems
The unit control system of low-voltage units can generally be integrated on one side of the generator section on the machine body, while high-voltage units generally require an independent unit control box to be arranged separately from the unit due to signal interference issues.
6. Differences in maintenance requirements
The maintenance requirements for high-voltage generator units in various aspects such as oil circuit system and air intake and exhaust system are equivalent to those of low-voltage units, but the power distribution of the units is a high-voltage system, and maintenance personnel need to be equipped with high-voltage work permits.
Post time: May-09-2023
