Admitted abnormal operation modes of turbogenerator
· the turbogenerator admits the durable operation at asymmetrical load if the currents in phases do not excess the admitted value for these conditions of operation of the turbogenerator at symmetrical load, and inverse current, at that, must not excess 8 % of rated value of stator current.
· the turbogenerator admits an operation at under-excitation mode at rated active power and power factor as 0,95 (leading).
· The turbogenerator admits an operation at asynchronous mode during 15 minutes at consuming active power not more 60 % of rated one, during 30 minutes – at consuming power not more 50 % of rated one, and durably – at consuming power not more 40 % of rated one.
Desing version
The turbogenerator version is horizontal.
The stator core and winding are immersed into the insulating oil. The oil volume filling the stator is limited by case, end shields and insulation cylinder placed into the split of stator core. The insulation cylinder and end shields, at the places of joining to stator case, are sealed with the rings of rubber cord. To extract the rotor for its overview and prophylactic repair, it is not necessary to drain oil from stator and remove the end shields. The stator case is one part and welded. The stator core is assembled of the insulated segments of electric steel in which, at stamping, the narrow rectangular holes creating the axial ducts at the core over which the insulating oil cooling the core floats, are cut off. The pressed core is laid axially and held by stuck packages and clamping non-magnetic elements. In the case, the core is fitted rigidly. The stator winding is three phase, two layer, with shortened pitch. The bars of the winding are done of the alternating hollow and solid wires. The oil floating over the ducts of the hollow wires cools the bars. The phases of the winding are connected into star.
The line and neutral terminals of the stator winding are led out the case of stator through the isolators and placed at the bottom of case. The plate, on which the terminals are fitted, is designed to connect the closed current supplies.
The rotor is done of the integral forging of special alloyed steel. The rotor winding consists of the concentric coils fabricated of the hollow copper with silver addition. The straight portions of the winding are fitted by slip rings of alloyed non-magnetic stainless steel. The cooling of the rotor winding is done by distillate which floats over the ducts of the wires. All coils over distillate are connected in parallel. The water supply and its drainage are fulfilled through the central hole of the shaft over the concentrically mounted pipes of stainless steel.
The slip rings are done of special steel and set onto the console shaft end. To cooling of the slip rings and brushes and remove the brush dust from an area of brush and contact device, between the slip rings on a shaft, the fan is mounted. The turbogenerator bearings are outboard thrust ones. The bearing from a side of the slip rings has the self-mounting insert with spherical setting in case. The bearing from a side of the turbine is built into the turbine case and supplied with the turbine.
The oil supply into the turbogenerator bearings are fulfilled from the lubrication system of the turbine bearings. To cool the turbogenerator, on the power plant, the cooling systems for stator and rotor with usage of equipment supplied with generator, must be mounted. The cooling of stator by insulating oil and of rotor by distillate is fulfilled over the close loop: electric pump – cooler – filter – cooled item – electric pump. For a circulation of oil, the watertight pumps without seals are used. At each system, the reserve pump, reserve cooler, reserve filter are installed. At cooling system of stator, for a compensation of temperature changes of insulating oil volume filling stator and system, at the input of the pumps, the extending sets are connected. One of them is operating, other is reserve one. The insulating oil purified from the mechanical additions and water with oil station of the power plant, before the stator filling and its cooling system, is degassed. The equipment for degassing and filling of stator and its system under vacuum, is supplied with the generator. One set of such equipment provides the maintenance of two or three identical turbogenerators installed at main room of the plant. The excitation system of the turbogenerator is thyristor one done with self-excitation circuit.