Cases-GoLead Intelligent

A Large Typhoon-Disconnect-Free Internal Turret Single-Point Mooring FPSO

Overview

As China’s first domestically built typhoon-disconnect-free internal turret single-point mooring FPSO, this unit suffered frequent generator trips caused by excessive transformer magnetizing inrush, severely limiting production efficiency. Field measurements showed inrush currents up to 7.69 p.u., repeatedly triggering generator overcurrent protection and leading to frequent energization failures.

Conventional inrush suppression solutions were impractical due to space constraints and limited effectiveness. By integrating the SID-3YL inrush suppressor—a compact, secondary-side device based on residual-flux cancellation—the inrush current was stably reduced to within 0.47 p.u., achieving a 100% energization success rate after commissioning in April 2025. The solution delivers source-level suppression with zero additional space occupancy, significantly improving power supply reliability and ensuring stable operation of the FPSO under extreme conditions.

Pain Points & Solutions

Pain Point 1: Power Supply Failures Caused by Magnetizing Inrush Current

During closing of the No. 1 main transformer VCB6 circuit breaker, the maximum magnetizing inrush current of phase B reached 31.148 A (7.69 times the rated value), triggering generator overcurrent protection and resulting in frequent energization failures and a significant decline in oil production efficiency. Such events can interrupt offshore operations and reduce daily crude oil output, particularly when rapid power restoration is required after storms—conditions under which conventional methods fail to meet operational demands.
Solution 1

Based on a residual-flux and bias-flux cancellation algorithm, the solution dynamically detects transformer residual magnetism and applies precise phase-angle control to cancel inrush current at its source. The system was directly integrated into the VCB6 switchgear on April 16, 2025, requiring no primary equipment modification and no additional hardware.
Pain Point 2: Space and Performance Limitations of Conventional Solutions

Traditional pre-magnetization methods require additional parallel magnetizing transformers or high-power resistors, occupying valuable space in already compact ship compartments. Moreover, these approaches only mitigate transient inrush magnitude and cannot suppress inrush at its source, often leading to repeated closing failures.
Solution 2

The solution adopts a pure secondary-side design, reducing device volume by 70% and making it well suited for space-constrained marine environments. By suppressing inrush generation at the source rather than relying on additional primary equipment to "share" inrush current, it significantly enhances on-site operational stability.
Pain Point 3: Reliability Challenges Under Extreme Operating Conditions

After offshore storms, the vessel requires complete power shutdown followed by rapid restoration. Conventional methods often fail due to repeated unsuccessful energization, making it difficult to ensure continuous power supply.
Solution 3

The system delivers high reliability, achieving a 100% first-time energization success rate and reducing post-storm power restoration time to minutes, ensuring continuous and stable offshore operations.

Values

Simple & Flexible

The device adopts a pure secondary-side design, significantly reducing onboard space requirements. It supports simple operation with one-click remote activation via the control system, streamlining procedures and improving ease of use.
Safety Assurance

The solution achieves a 100% first-time energization success rate with high reliability, enabling rapid power restoration after outages under extreme weather conditions and ensuring stable on-site production efficiency.

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