Operation of crane group electric drive with frequency control on a marine vessel
Authors:   Kerch State Maritime Technological University, Savenko A.E. , Savenko P.S. ,   Kerch State Maritime Technological University
Published: April 2024

One of the most important tasks to increase efficiency and reliability of modern sea vessels is the study of the operation of electric drives with frequency control. There is a sufficient number of scientific studies in which analysis and research is carried out on the topic of frequency control of electric drives. Problems occur when operating special-purpose sea vessels equipped with a powerful crane with a lifting capacity of 250 tons. The ship crew when working in the open sea, cannot fully operate the cargo crane at full speed, since it is suddenly switched off by the protection and an emergency occurs. In this regard, it is relevant to improve the use of powerful group electric drives on sea vessels. The authors have used a passive experiment method to study the operation of six electric motors with a power of 400 kW, which drive the winch of the crane main hook. The operation of the frequency converter and multichannel oscilloscope has been constantly monitored. Using the standard functions of the frequency converter control system allows you to monitor and obtain oscillograms of six parameters simultaneously: motor torques, active motor powers and engine rpm speed, total winch current. The necessary adjustments and settings of the frequency converter control system are carried out by changing the parameterization of the encoder signal processing card. The design of a pedestal crane with a lifting capacity of 250 tons on the pipe-laying vessel Seven Vega is considered. Experimental oscillograms have been obtained characterizing the operation of the crane main hook winch. The moment of trip (knockout due to overload) has been recorded at the maximum speed of one of the six drive electric motors. It has been established that such protection makes it impossible to continue lifting or lowering the load. The conducted studies have shown that for encoders used in a group crane electric drive, it is necessary to use the law of calculation of the rotation speed using the full duration of the pulse period of one channel. After changing the parameterization of the encoder signal processing map, which provides calculation of the rotation speed of each of the six electric motors, long-term tests have been carried out. The tests results have shown the proper operation of the crane main hook winch at maximum speeds. The results of the conducted research make it possible to ensure high-quality operation of a group crane electric drive with frequency control. As a result of the study, it is established that when asymmetry of pulse duration is detected in the operation of optical encoders, it is necessary to change the speed calculation method of the frequency converter to use the full duration of the pulse period of one channel, and not the difference between the fronts or drops of the pulses of four channels. The experience of the conducted research and repair and adjustment work can be used in various electrical complexes that use group electric drives with Siemens frequency converters.