Cases-GoLead Intelligent

A 500 MW Wind Farm with a 220 kV Step-Up Substation of Huaneng Group

Overview

Since the installation of the first GE 2.5-132 wind turbine in June 2019 and the first grid connection in August 2019, this project achieved the grid connection of 41 wind turbines in a single day, setting a new record for both Huaneng Group and GE in the Asia-Pacific region.

Construction of the project began in 2018, and a total of 200 GE 2.5-132 wind turbines have been installed to date. After full commissioning, the wind farm is expected to generate approximately 1.17 billion kWh of electricity annually, equivalent to saving 350,000 tons of standard coal per year and reducing emissions of nitrogen oxides and other harmful gases by 1.328 million tons, as well as 3,670 tons of dust, delivering significant social and environmental benefits.

The GE 2.5-132 onshore wind turbine is a customized model specifically designed by GE for low-wind-speed conditions in China.

However, due to frequent power fluctuations inherent to wind power generation, the step-up transformers at the substation are prone to severe magnetizing inrush currents during no-load energization and fault recovery, posing risks to equipment safety and grid stability. This challenge can be effectively addressed through a comprehensive solution combining residual-flux and bias-flux cancellation technology with optimized phase-selective closing.

The SID-3YL microprocessor-based inrush current suppressor provided by our company offers key advantages such as flexible adaptation to multiple operating scenarios, easy installation and commissioning, and low operation and maintenance costs. It significantly enhances the safety of main transformer switching operations while ensuring the overall power supply reliability of the wind farm.

Pain Points & Solutions

Pain Point 1: Magnetic Circuit Saturation Caused by Superposition of Residual Flux and Bias Flux

After transformer de-energization, residual magnetism remains in the core. During breaker closing, the bias flux generated by sudden voltage application may superimpose on the residual flux. If the total magnetic flux exceeds the saturation threshold, magnetizing inrush currents of 6–8 times the rated current may occur, leading to a sharp increase in winding mechanical stress, accelerated insulation aging, and even the risk of catastrophic failure.
Solution 1

Residual Flux Monitoring and Reverse Bias Flux Generation: The device continuously monitors the magnitude and polarity of residual magnetism after transformer de-energization and actively generates reverse bias flux during closing to keep the total magnetic flux below the saturation threshold. Precise closing is performed at voltage angles of 90° or 270° (corresponding to zero magnetic flux) to avoid abrupt flux changes.
Pain Point 2: Insufficient Closing Phase Control Accuracy

Conventional circuit breakers exhibit relatively large closing time deviations, causing phase angles to deviate from the voltage zero-flux points (90° or 270°) and preventing effective inrush suppression.
Solution 2

The solution is compatible with both three-phase gang-operated and single-pole-operated circuit breakers, with allowable operating time dispersion extended to ±2 ms. Built-in disturbance recording, event logging, and GPS time synchronization are provided, and the system supports IEC 61850 integration with the step-up substation monitoring system for remote strategy adjustment.
Pain Point 3: High Operation and Maintenance Complexity

If transformer residual magnetism changes after maintenance-related de-energization, conventional phase-selection closing strategies may become ineffective.
Solution 3

When magnetic flux cancellation cannot be applied, the system fixes one phase to close at 90° voltage angle, ensuring that the inrush current of at least one phase remains controllable.

Values

Flexible & Reliable

Supports switching of non-linear loads such as transformers, capacitors, and reactors, meeting the diverse operational requirements of wind farm step-up substations. Compatible with voltage levels from 10 to 110 kV, and readily adaptable to future expansion.
Simple & Efficient

An integrated design eliminates the need for additional independent monitoring devices and enables direct replacement of conventional protection modules. With a built-in strategy library and automatic phase-angle calibration, on-site commissioning time is reduced to just a few hours.
The long-life design (compatible with circuit breakers rated for ≥30,000 operations), combined with condition monitoring, enables condition-based maintenance, reduces manual inspection frequency, automatically records residual flux data, avoids manual demagnetization, and lowers operational safety risks.
Fast & Cost-Efficient

Prevents equipment damage or unplanned outages caused by inrush current, reducing annual operation and maintenance costs by 30–40%. By suppressing inrush impacts, transformer service life can be extended to over 25 years, reducing asset replacement frequency and overall lifecycle costs.

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