Summary

China State Shipbuilding Chengxi Co., Ltd 1600t crane ship is mainly used for marine operat∑ion. The main function is hoisting. The hoisting ab∞ility of the crane ship is 1600t. The electrical system control mainly involves hois™ting, variable amplitude control system, shifting and mooring winch control system. Cr£ane control system uses distribution control method, where CPU of PLC is used to centraliz∏ed control management and exchange data with remote input/output modules b♠y distributed I/O and communication adapter. Hoisting, variable amplitude, shift®ing and mooring mechanism drivers all use variable frequency drive system to control the AC in"duction motor. The AC transmission system not only eliminates the h≠igh order harmonic component interference effectively, but also extends ♠the speed range of the motor speed, which makes the motor speed vary ₩from 0 to over rated speed. Precise speed control and reliability raise the production efficiency∏ in the transmission process. Furthermore, energy sa ving can be also achieved. DTC ensures high control precisio¥n when encoder is unavailable.

Solution

The crane is powered by on board generator set. The voltage level is 400VACπ/3P/50Hz.  Main/slave dry type 12 pulse 3 winding rectifier transformer©s (phase difference of secondary side windings is 30 degree) powered for main hoi&sting, secondary hoisting, vary amplitude, shifting and winching mechanisms. 

The drivers of winch motor use ABB ACS800 series VV★VF equipment. The produced energy is released by external power resistor during the mechanism↕ brake or decline. The power resistor is placed outside ∑the power supply room.

The control part uses Siemens S7-400 series PLC to achieve the logic control, safety ∑protection, fault diagnosis and status monitoring etc. 

VVVF device communicates with monitoring device by Profibus-DP, which can achieve fast contφrol and monitoring device running status; meanwhile, i<t reduces the cable laying and makes the operation aσnd maintenance convenient. 

Schneider products are used for the low voltage components.

The hoisting mechanism involves weighing device (moment protection), safety prote±ction device, sudden halt protection, TV monitoring system, crane operatio≠n platform, shifting winch operation platform and anemometer etc.

VVVF input is installed with passive harmonics filter to reduce the ™effect of harmonics due to the complete variable fr×equency drive control