The Xinshida AS520 frequency converter applied to quay-side container cranes in the lifting industry.
2025-06-04
The Xinshida AS520 frequency converter applied to quay-side container cranes in the lifting industry.
Project Background
Compared with other transmission machinery, port lifting equipment places even more stringent demands on inverters in terms of safety and performance. Xinsida has developed a high-performance four-quadrant inverter based on vector control, which has been successfully deployed on quay crane No. 130 at the Zhendong Container Terminal Branch of Shanghai Port Group, marking an important step toward the localization of electrical control systems for port lifting equipment.
The shore crane No. 130, located at the Zhendong Container Terminal Branch of Shanghai Port Group’s Phase II Waigaoqiao, was manufactured by Shanghai Zhenhua Heavy Industries (Group) Co., Ltd. and put into operation in July 2003.
Customer needs
It must meet requirements such as frequent start-ups and shutdowns, significant vibration and shock, substantial overload capacity, and various harsh operating conditions.
It must also meet the characteristics of power supply: large harmonic components, rapid changes in current and voltage, and, at the lower end, ensure smooth speed regulation with constant torque.
Ensure full-power output at high speeds under weak magnetic field conditions, and guarantee sufficient output torque across low, base, and high frequencies; more importantly, meet the safety requirements for port machinery.
Xinshida Solution
Proposal Description
1. Matching issues between the original brand PLC and the new Shidada frequency converter control.
Brake control and dynamic performance—since the system is designed to lift containers, it must ensure that the motor can provide sufficient torque even at very low speeds to both lift and lower the containers. Moreover, during both lifting and lowering operations, there must be no cable slippage whatsoever; otherwise, serious safety hazards could arise.
Table of Motor Drive Equipment for Quay Crane No. 130
2. Issues with using the original-brand LCL filter in conjunction with the new Shida AFE.
New Times AFE Measured Data
3. Synchronous control of large vehicles
The large carriage is driven by 10 motors, of which 8 are controlled by a single inverter, while the remaining 2 are controlled by another inverter. Moreover, the motor power and gear transmission ratios of the two motor groups differ from each other. To ensure synchronous operation of the large carriage, a master-slave control approach is adopted: the master inverter’s speed signal is transmitted to the slave inverters via a CAN bus, thereby guaranteeing consistent final speeds for the two inverter-driven motors of the carriage.
4. Smooth starting and rapid braking of the vehicle
Four small vehicle motors are controlled by a single inverter, employing closed-loop vector control to achieve smooth motor operation.
5. The pitch motor has not been used for many years.
Since the condition of the pitch motor was unknown before the retrofit, after the retrofit and with the inverter running, the motor failed to start. After extensive testing, it was determined that the motor had already been damaged. Once the motor was replaced, everything returned to normal.
6. Communication issues
The original brand PLC did not support Profibus DP. We adopted a third-party SX bus to convert to the Profibus DP bus, which made commissioning complicated. After switching to the DP module designed by Xindasheng itself, compatibility issues with the original brand system initially arose frequently, leading to false communication alarms and faults. Later, by modifying the PLC communication program and adding relevant accessories, we ensured that communication functioned normally.
Scheme Composition
In this retrofit, the original brand’s PLC and LCL filter will be retained, while the original-brand AFE and variable frequency drives will be replaced. The data exchange between the PLC and the VFD driver will be switched from the original brand’s proprietary SX bus to a universal Profibus-DP communication protocol. The control flow of the upgraded 130 system is shown in the figure below.
The upgraded Xinda electric control system is:
● 1 original-brand PLC with an added SX-to-Profibus-DP module;
● One AS510-4T0400 400kW AFE replaces the RHC400-4C AFE;
● Two AS520-4T0160 units replace the original FRN160VG7S-4LC variable-frequency drives, each driving either one 132-kW hoisting motor or eight 18.5-kW motors and two 15-kW trolley travel motors, respectively.
● One AS520-4T0132 inverter replaces the FRN132VG7S-4A inverter to drive four 22-kW trolley motors or one 55-kW pitch motor.
130 Quay Crane System Block Diagram
Associated products
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Project Results
Operating status
The electrical control system upgrade for Quay Crane No. 130 began on January 30, 2012, and the installation and commissioning work was completed by February 4, 2012. The crane was put into operation on February 5.
1. Operation status of the AFE converter
The New Times AS510 active front-end AFE features reduced current harmonics, stable bus voltage, and minimized reactive power. In actual operation, aside from communication failures that occurred during the commissioning phase, the system has been running stably ever since. Testing has shown that under various load conditions on quay-side gantry cranes, the rectifier’s DC output voltage and feedback voltage remain stable, with voltage fluctuations within the normal range. Voltage harmonics are below 1.5%, and current harmonics are below 5%. Based on test data collected during the pilot production phase under different operating conditions, the system fully meets the requirements for reversible AC-to-DC conversion needed by the 130-quay gantry cranes. Figure 5 shows the operational diagram of the AFE.
Power grid waveform
2. Inverter (AS520-4T0160 and AS520-4T0132) Status
Since the start-up and trolley frequency converters were put into trial operation, no hardware failures have occurred, and the software has been running stably and reliably. Figures 6-8 show, respectively, the weak-magnetic-field waveform, the master-slave synchronization waveform, and the cabin-hanging protection waveform.
Figure 6: Weak Magnetic Field Curve for Downward Lifting
Figure 7: Master-Slave Control Waveforms
Figure 8: Cabin Protection Curve
During the trial production phase following the completion of the retrofit, after numerous adjustments and fine-tuning of the control software, the number of control software faults in the frequency converters has decreased from the initial seven types to only occasional speed deviation faults that can be reset. As a result, the number of resettable faults per 1,000 TEUs handled at the quay crane operations dropped from the initial level of 20.74 in February to fewer than two per 1,000 TEUs in March, April, and May. Following a final fine-tuning in May, the number of resettable faults per 1,000 TEUs further declined to less than 0.3 in June, July, and August. This significant reduction in fault frequency confirms the high reliability of the Xindada frequency converter hardware and the precision of its control software. Moreover, when the lifting motor’s brake is engaged, the system operates smoothly with minimal noise and stable performance, and the current waveform remains smooth. Based on the current operational status of the 130 quay cranes, the Xindada frequency converter system fully meets the requirements for reliable operation of this type of crane. The data in Table 3 are sourced from statistical records provided by the ZhenDong Container Terminal Branch as of August 23.
Table 3: Operational Data Statistics Table
Within the first month of operation, due to unfamiliarity with the terminal’s operating conditions—particularly a lack of deep understanding of the drivers’ operational habits—there were relatively frequent reset-related malfunctions. However, as communication between the project teams on both sides deepened, these malfunctions have become increasingly rare in the 130 retrofit project. Based on the performance over the past eight months since the retrofit began in February, the project has fully met the operational requirements for the 130 quay crane.
Summary
Field tests and actual measurements have shown that the inverter’s electrical performance meets the technical requirements for electrical control systems used in port cranes. Its key technical performance indicators are comparable to those of similar products both domestically and internationally, and some indicators even outperform their counterparts at home and abroad. The inverter plays an important role in ensuring stable operation of port cranes, enhancing production efficiency, reducing maintenance costs, and alleviating workers’ physical labor intensity, thereby achieving significant economic and social benefits.
