Parallel Operation Impulse Current Calculation Method 1

In today's electrified era, power generation equipment is widely used. The fluctuation of the load leads to changes in the number of operating generators in the power system. The parallel operation of diesel generators (including grid - connected operation of generators) is a frequent and important operation. The parallel operation of generators has numerous application fields, such as ships, mines, and power plants, and plays a significant supplementary role in the national production and people's lives.

As the single - unit capacity of synchronous generators continues to increase, when the two - phase circuits are connected at the moment of paralleling, appropriate paralleling conditions can enable a smooth transition from the original two stable operating states to one stable operating state. Improper operation will generate a harmful inrush current, which may cause electrical damage to the windings of the generator set and even produce a large electromagnetic torque, resulting in mechanical damage to the generator shaft system. Therefore, the suppression of the paralleling inrush current has always been one of the key technologies under research and is also a basic requirement for paralleling. To ensure the stable parallel operation of the generator set, the inrush current is generally limited not to exceed the rated current of the generator set.

The magnitude of the inrush current during the closing of a synchronous generator for paralleling is related to factors such as the phase difference, amplitude difference, and angular difference between the paralleling generators. The phase difference is the key factor affecting the inrush current during parallel operation. The nature of the inrush current and its impact on the generator and the system are analyzed, and the blocking angle of the synchronizing blocking relay is calculated. The reasons for the extended closing time and excessive inrush current during the grid - connected synchronization of large - scale turbo - generators are analyzed, and the closing phase angle is calculated.

In the process of the parallel operation of synchronous generators or the setting calculation of power plant generators, generally only the influence of the phase difference on the inrush current is considered. In reality, when the generator is closed for paralleling, multiple factors often act together. Therefore, the calculation of the inrush current should take into account the combined effects of multiple factors.

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