After two generator units are connected in parallel, the connection between them is mainly at the endpoint of the generator, which is the busbar. Therefore, the analysis of the problem must first start from the electrical aspect.
Each unit includes links such as diesel engine, regulator, generator, voltage regulator, etc. The endpoints of the two generators are connected in parallel through a busbar. The rotor of each generator is connected to the crankshaft of the diesel engine through a coupling. Because the generator rotor and the rotating part of the diesel engine are a whole, discussions about the generator rotor actually include the rotating parts of the diesel engine, and vice versa.
For single machine diesel generator sets, regardless of the size and composition of the load, the voltage regulator of the generator can automatically maintain the generator voltage within the required accuracy by changing the excitation current of the generator, while the governor of the diesel engine automatically maintains the diesel engine speed within the required accuracy by adjusting the fuel supply of the diesel engine. From an electrical perspective, it ensures the stability of the frequency and voltage of the electrical equipment, and maintains a balance between the electrical energy consumed by the load and the fuel energy provided to the diesel engine. If the external load of each unit does not exceed the allowable values of the generator and diesel engine, then there will be no abnormal operation of the unit.
Assuming that after the entire step, the two units are connected in parallel and the switch K is closed. Obviously, the function of the voltage regulator and governor to maintain constant voltage and speed has not changed as a result, but the only difference from before is that the load that was originally borne by each generator has now been shared by two generators. Therefore, in addition to the overall energy balance, there is also a problem of how the two units distribute the load. In terms of their principles, speed governors and voltage regulators cannot directly reflect the load relationship between parallel connected groups. Therefore, it is necessary to analyze the relationship between the load size of the generator and its internal parameters, as well as the relationship between the load of the generator and the characteristics of the speed governor and voltage regulator, in order to find the law of load distribution between parallel connected groups and the method of controlling load distribution. The vast majority of problems with parallel operation are related to how to allocate their common loads between parallel connected groups.
For details of the characteristics and precautions of parallel operation of diesel generator sets, the installation and commissioning of diesel generator sets, and the maintenance and management of diesel generator sets, please pay attention to Jiangsu Starlight Electricity Equipments Co.,Ltd..
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