Load Sharing of Parallel Connected DC Generators
The load gets shifted to another generator by adjusting induced e.m.f., but in modern power plant, everything has been done by “sychroscope” which gives instruction to governor of the prime mover. Let us suppose that two generator having different load voltage. Then the load sharing between these generators will be
The value of current output depends upon the values of E1 and E3 which could be managed by field rheostats to keep the bus-bars voltage constant.
Advantages of Parallel Operation of DC Generators
Cost Effectiveness:- Electric power cost reduces when generator produce electricity according to their capacity and easily manage demand and supply requirement. If there is less requirement of power, one or more units can be taken on hold or startup visa versa.
Smooth Supply of Power:- In case of breakdown of generator, the supply of power will not get disrupted. If something goes wrong in one generator, the continuity of power can be continued by other healthy units.
Easy to Maintain:- The routine maintenance of generator is required time to time. But for that supply of power cannot be obstructed. In parallel generators the routine checkup could be done one by one.
Easy to Increase Plant Capacity:- The demand of electricity is increasing day by day. To meet the requirement of power generation, additional new unit can run paralleled with the running units.
Precautions During Parallel Connection
1 The specification of each generator is different from one another. When they are synchronized together, their speed are locked into the overall speed of the system.
2 The entire load of the system should be distributed in all the generators.
3 There should be a controller for keeping check on parameters of the engine. This can be done with modern digital controllers which are available in market.
4 Voltage regulation in the whole system plays an important role. In case of voltage drop in one unit compare with other units, end up bearing the whole voltage load of the system of parallel generators.
5 While connecting terminals to the bus-bars, extra precaution should be made. If generator is connected with wrong polarity of the bar, it may result to a short circuit
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