BASICS OF SYNCHRONIZATION OF GENERATORS:
Generators are often connected in parallel to increases the power capacity, control in load management, ease of maintenance and redundancy. However these generators are often removed from service for maintenance, during variation of loads, emergency outages and in other situation. Generators need to be synchronized before reconnecting back to the power system .
An improper synchronization system can affect the healthy power system and results in electrical and mechanical transients that can damage the prime mover, generator, transformers and other power system components.
CONDITIONS FOR SYNCHRONIZING GENERATORS:
For the generators to be paralleled and synchronized correctly each of the sets should have the below characteristics.
Frequency: the frequencies must be same
Voltage: The generators should produce or set be produce same voltage otherwise there will be a large current flow when the switch is closed.
Phase angle: The two systems should have the same number of phases either single or three phase.
Phase rotation: For three phase system, each of the three phases must be matched. This prevents excessive mechanical and electrical stresses as well as avoiding surges.
Voltage phase angle: The waveform should be matched such that they rise and fall together. There should be no angle difference between the phases, it should be zero.
ADVANTAGES 0F SYNCHRONIZING GENERATORS:
Increased reliability and redundancy: Improving reliability and redundancy for both critical and non-critical loads. The system ensures that there is always constant power to critical loads, and if one of the generators fails, the load is supplied by the other one or parallel unit.
Low cost of power generation: Cost of generation increases with generator size and is more for rating above 600 kW. This is due to the fact that the market for smaller engines is higher, hence more are manufactures, resulting in lower cost. Using several smaller generators becomes more economical than a single large generator.
Decreased light loading of the generator prime mover: In most installations, the load varies from time to time and it is common to have a generator running at 30% of its capacity when the load is low. This may cause wet stacking. The efficiency of the prime mover is normally higher when the load is between 75% and 100% and a light load means that the generator operation is inefficient. Using a smaller generator increases efficiency hence cost would be reduced.
More control and savings on generating cost: The total amount of power supplied from several small generators is equal to the power supplied by one large unit. However there is more control and balancing in the small generators. One can balance the load over the different circuits and decide on the power to generate at any particular time based on the load.
Cost saving: The parallel system can achieve huge savings when all generators are operated above 75% of their rated load. This is the point at which generators use the minimum fuel.
Extensibility and flexibility: The use of several small generators to supply a varing load is better to spend too much on a big generator whose full capacity is rarely used. Generators can be added gradually as demand increases.
FAULTY GENERATORS SYNCHRONIZATION:
An improper synchronization of parallel generators can affect the healthy power system as follow
Damage to the generators and step-up transformer winding due to high currents
Generator & prime mover damage due to mechanical stress caused by rapid acceleration/deceleration need to bring the rotating masses in synchronization
Disturbance to the power system such as oscillations and deviating voltages that are not nominal
Keeps the generators from staying online and pickup loads when the protective relay determines the generators is running in abnormal operating conditions, which can cause the generator to shutoff
Setting up parallel generators is a complex procedure that requires a qualified electrical professional.
A well designed system provides backup power and a variable output. Using the correct paralleling generators helps the consumer to achieve the maximum output when the power demand is at its peak while providing the minimum output when the load requirements are low.
All your hard work around here doesn’t go unnoticed.
ConversionConversion EmoticonEmoticon