Download the app

What is the Parallel Operation of DC Generators?

Encyclopedia
08/19/2024

What is the Parallel Operation of DC Generators?


Parallel operation definition of DC generator


In modern power systems, power is usually provided by many parallel synchronous generators to ensure continuous operation of the plant. The use of single large generators is now obsolete. Having two generators in parallel helps keep them in sync. Adjusting their armature currents and properly connecting them to the bus bars can solve any synchronization problems.


Busbar connection


Generators in power plants are connected by thick copper bars, called busbars, that act as positive and negative electrodes. To parallel the generator, connect the positive terminal of the generator to the positive terminal of the bus, and the negative terminal of the generator to the negative terminal of the bus, as shown in the figure.

To connect the second generator to the existing generator, first increase the speed of the prime mover of the second generator to the rated speed. Then, close switch S4.


Circuit breaker V2 (voltmeter) is connected to the open switch S 2 close to complete the circuit. The excitation of generator 2 is increased with the help of a field rheostat until it produces a voltage equal to the bus voltage.


Next, turn off the main switch S2 to connect the second generator in parallel with the existing generator. At this point, generator 2 is not yet powered because its induced electromotive force is equal to the bus voltage. This state is called "floating," which means the generator is ready but not providing current.


In order to supply current from generator 2, its induced e.m.f. E must be greater than the bus voltage V. By strengthening the excitation current, the induced electromotive force of generator 2 can be increased and the supply current can be started. In order to maintain the bus voltage, the magnetic field of generator 1 is weakened so that the value remains constant.


The field current I is given by Where, R


786715bccdb1f10821bef3c6af44e0f3.jpeg


b6f2dec2a3e26264fb418a323d48f1e6.jpeg


Load distribution


By adjusting the induced electromotive force, the load is transferred to another generator, but in modern power plants everything is done by the "sychroscope", which gives instructions to the governor of the prime mover. Let's assume that the two generators have different load voltages. Then the load distribution between these generators will be the value of the current output depending on the value of E 1 and E3 which can be managed by a field rheostat to keep the bus voltage constant.


6834c43b1adc011cbae18a4631f44ffe.jpeg


Advantage


Smooth power supply: If the generator fails, the power supply will not be interrupted. If one generator fails, the other healthy generator sets can continue to maintain continuity of power.


Easy maintenance:Routine maintenance of the generator is needed from time to time. But for that, the power supply must not be impeded. In parallel generators, routine checks can be carried out one by one.


Easy to increase factory capacity: Electricity demand is increasing. To meet the needs of power generation, additional new units can be operated in parallel with operating units.


Matters needing attention


  • The specifications of each generator are different. When they are synchronized together, their speed is locked into the overall speed of the system.



  • The full load of the system should be distributed among all the generators.



  • There should be a controller to check the engine's parameters. This can be done with modern digital controllers available on the market.



  • Voltage regulation plays an important role in the whole system. If the voltage of one unit drops, it ends up bearing the entire voltage load of the shunt generator system compared to the other units.


  • Extra precautions should be taken when connecting terminals to bus bars. If the generator is connected to the wrong rod polarity, it may cause a short circuit.


Topics
Machines DC Generators Parallel Operation
Encyclopedia

The Electricity Encyclopedia is dedicated to accelerating the dissemination and application of electricity knowledge and adding impetus to the development and innovation of the electricity industry.

Cost Differences and Performance Comparison of 35kV New Energy Transformers Based on Dry-Type, Mineral Oil, and Vegetable Oil
Cost Differences and Performance Comparison of 35kV New Energy Transformers Based on Dry-Type, Mineral Oil, and Vegetable Oil
For users, when purchasing a 35kV new energy transformer, choosing between dry-type, mineral oil-filled, or vegetable oil-filled types involves multiple considerations. These include user habits, maintenance-free performance, safety and fire resistance, volume and weight, among others. However, cost differences are undoubtedly one of the most crucial factors.To illustrate the issue intuitively, this paper selects a three-level energy efficiency dual-winding new energy transformer with a rated ca
Ron
07/26/2025
What is the connection group of a transformer?
What is the connection group of a transformer?
Transformer Connection GroupThe connection group of a transformer refers to the phase difference between the primary and secondary voltages or currents. It is determined by the winding directions of the primary and secondary coils, the labeling of their start and end terminals, and the connection mode. Expressed in a clock-like format, there are 12 groups in total, numbered from 0 to 11.The DC method is commonly used to measure the transformer's connection group, mainly to verify whether the con
Vziman
07/26/2025
What is the sequence for powering down the transformer?
What is the sequence for powering down the transformer?
The sequence for shutting down a main transformer is as follows: when de-energizing, the load side should be shut down first, followed by the power supply side. For energizing operations, the reverse order applies: the power supply side is energized first, then the load side. This is because: Energizing from the power supply side to the load side makes it easier to identify the fault range and take prompt judgment and handling measures in case of a fault, preventing the fault from spreading or e
Rockwell
07/26/2025
What are the methods for switching operations of station transformers?
What are the methods for switching operations of station transformers?
Let's take an auxiliary power system with two station transformers as an example. When one station transformer needs to be out of service, there are two operation methods: non-interruptive power supply and instantaneous power interruption. Generally, the method of instantaneous power interruption on the low-voltage side is preferred.The operation method for instantaneous power interruption on the low-voltage side is as follows:Open the 380V power incoming circuit breaker of the corresponding sec
Vziman
07/26/2025
Source professional electrical partners, experts, and explore smart grid & energy solutions.
Inquiry
Download
IEE-Business is dedicated to serving the personnel in the global power industry.
Join IEE-Business, not only can you discover power equipment and power knowledge, but also canhnd like - minded friends!
App Store App Store App Store App Store App Store App Store App Store App Store
App Store