The synchronization of generators in parallel arises as a need to supply large demands of energy that would be impossible to supply with a single generator. Parallel synchronization also applies to those installations that require a much greater reliability and safety mechanism , since having more than one generator operating at the same time is more complicated to fail or fail in unison, thus ensuring continuity, At least partially, of the electricity supply.
The parallel connection of two or more generators involves a series of complex operations that allow the machine to be synchronized. Conditions required for parallel synchronization. Connecting the generators in parallel arbitrarily would possibly cause severe damage and the load may lose power, so that to make the parallel connection of two or more generators the following aspects must be taken into account. Equal Voltages. If the generator voltages are not exactly the same, there will be a very large current flow when the switch is closed.
To avoid this problem, each of the three phases must have exactly the same magnitude of voltage and phase angle as the conductor to which it is connected. And also make sure that the RMS line voltages are equal. Equal frequencies. The frequencies of the 2 or more generators as well as the voltages must be the same as they would cause serious problems. Phase Sequences. All generators must have the same phase sequence. The phase angles of all phases must be the same , the sequence in which the phase voltage reaches its peak in all generators must be the same.
Similar constructive characteristics. A recommended factor that greatly facilitates synchronization, is that the machines must be the same, it is obvious that it will not be possible to obtain two totally identical generators, but unless they look a lot in their constructive part , besides that, the powers which each deliver is of similar value , and preferably of the same manufacturer.
In the majority of cases for generator synchronization, the synchronization process is automated via an automatic synchronizer with manual control capabilities that can be used in backup situations. Browse Used Generators. A generator cannot deliver power to an electrical power system unless all the aforementioned parameters exactly match those of the network. The need for synchronization arises when two or more alternators work together to supply the power to the load.
Since electrical loads do not remain constant, the two or more generators supplying the power need to be interconnected and operate in parallel to handle larger loads. Using a series of small units instead of a single generator is known as parallel operation.
Synchronization is critical for parallelization, and many commercial plants prefer this setup for its:. These parameters are:.
Your generator synchronization procedure will help you determine if these parameters are equal between your bus bar and generator alternators.
Generator synchronization can be a complex idea to understand, but here are the basics of three techniques for generator synchronization:. Modern synchronization equipment automates the entire synchronization process in order to avoid manual lamps and synchroscope observations. These methods are far more reliable. Figure 2: Matching phase angle image: cpower. 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 more parallel unit. Low cost of power generation : Cost of generation increases with generator size and is more for ratings above 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. This may cause wet stacking. Using a smaller generator increases efficiency, hence a cost reduction.
More control and savings on generating costs : 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 smaller 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. Expandability and flexibility : The use of several generators makes it possible to supply a varying load without piling up costly units or spending too much on a big generator whose full capacity is rarely used.
Generators can be added gradually as demand increases. 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. A Generator cannot deliver power to electric power system unless its voltage, frequency and other parameters are exactly matched with the network.
Synchronization is accomplished by controlling the exciter current and the engine speed of the generator. The need for synchronization arrives, particularly when two or more alternators are working together to supply the power to the load. This is because electrical loads are not constant and they vary with time depending on the load and hence it is necessary to interconnect two or more alternators operating in parallel to supply larger loads.
Synchronization matches various parameters of one alternator or generator to another alternator or to the bus bar. The process of synchronization is also called as Paralleling of Alternators or Generators. In most commercial power plants, several small units supply the power rather than single large unit.
This is called as Parallel Operation of Generators. The reasons for preferring this practice are enumerated below. Several small units are more reliable than single large unit.
This is because, if one alternator is failed, other alternators are still active and hence the whole system will not be shutdown. In case of periodic maintenance, break-down or repairs of one alternator, it must be shutdown and removed from service.
Since the other machines are operating in parallel, the interruption to supply the load is prevented. The load requirements in the central station changes continuously. During light-load periods, only one or two generators are operated to supply the load demands.
During peak-load demands, additional alternators are connected in parallel to meet the demand. Generators run most efficiently when they are loaded at their rated values. Due to the operation of few generators at light-loads and more generators at high peak loads efficiently loads the generators.
As the demand for electric power is increasing continuously, utility companies have been increasing the physical size of the generating plants by adding more alternators. So, these alternators have to be connected in parallel with the existing generator equipment.
There are certain requirements that must be met for successful paralleling of alternators. The following conditions must be met in order to synchronize a generator to the grid or with other generators. The phase sequence of the three phases of the alternator which is being connected to the power system bus must have the same phase sequence as that of the three phases of the bus bar or electric grid.
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