Project Overview
Reliable relay protection systems are essential for the safe operation of modern power plants. During commissioning and maintenance, relay protection devices, synchronizing equipment, and fast transfer systems must be thoroughly verified before generating units are placed into service.
In February 2025, HKVTEST engineers provided urgent on-site technical support for a customer involved in commissioning work at a combined cycle power plant in Zhuhai, China. The project included relay protection testing, fast transfer device verification, generator synchronization testing, and operator training using the HZJB Six-Phase Relay Protection Tester.
Project Background
A power engineering contractor urgently contacted HKVTEST after its relay protection tester failed during an ongoing commissioning project.
Because the replacement equipment was required immediately to avoid delaying the project schedule, HKVTEST arranged rapid delivery and dispatched an experienced technical engineer to provide both equipment support and on-site guidance.
The commissioning work was carried out at a combined cycle gas-fired power plant, where relay protection verification was being performed on auxiliary power systems and generator synchronization equipment.
Project Challenges
The project presented several technical challenges:
- The original relay tester failed during commissioning.
- Tight project deadlines required immediate replacement.
- Synchronizing devices had to meet strict voltage and frequency requirements.
- Multiple relay functions required verification before unit startup.
- Customer engineers needed training on the new relay protection tester.
Rapid technical support was essential to ensure that the commissioning schedule remained on track.
Testing Equipment Used
The following equipment was used during the project:
- HZJB Six-Phase Relay Protection Tester
- Voltage and current output test leads
- Generator synchronizing relay testing software
- Auxiliary power fast transfer testing functions
The HZJB Six-Phase Relay Protection Tester supports automatic synchronization testing, protection relay verification, sequence testing, and programmable voltage/current output, making it suitable for substations, power plants, and industrial electrical systems.
Fast Transfer Device Testing
After arriving on site, HKVTEST engineers worked with the customer's commissioning team to test the auxiliary power fast transfer device.
The relay tester supplied simulated working power and standby power voltages.
During the test:
- Rated voltage was applied to the normal power source.
- The working source voltage was gradually reduced.
- When the undervoltage threshold was reached, the fast transfer device automatically switched to the standby source.
- Switching performance was smooth and stable without abnormal operation.
The test confirmed that the fast transfer system responded correctly according to the protection settings.
Generator Synchronization Test
Following the plant shutdown and completion of safety procedures, synchronization testing was carried out for the generating units.
The combined cycle power plant consisted of:
- Gas turbine (system side)
- Steam turbine (incoming side)
Using the synchronization testing software built into the HZJB Six-Phase Relay Protection Tester, engineers simulated both electrical systems.
The tester allowed independent adjustment of:
- Voltage
- Frequency
- Phase angle
Automatic synchronization mode was selected, enabling the synchronizing device to control voltage and frequency adjustments until synchronization conditions were achieved.
The synchronizing relay successfully issued the closing command once the following requirements were satisfied:
- Voltage difference within 3%
- Frequency difference within 0.15 Hz
- Phase angle within the allowable synchronization range
The synchronization process was completed successfully without abnormalities.
Relay Verification
Additional relay verification tests were performed using the relay tester's automatic ramp function.
Three relays installed in the synchronization control cabinet were tested.
Measured results showed:
| Test Item |
Result |
| Pickup Voltage |
Approximately 74 V |
| Dropout Voltage |
Approximately 50 V |
| Relay Operation |
Passed |
All measured values met the required commissioning specifications.
Technical Training
Besides completing the testing work, HKVTEST engineers also provided practical training for customer personnel.
The training covered:
- Equipment connection
- Software operation
- Automatic synchronization testing
- Relay parameter configuration
- Test result interpretation
- Safety procedures
The customer engineers were able to independently operate the tester after the training.
Project Results
The project was completed successfully with the following outcomes:
- Fast transfer device verified successfully.
- Generator synchronization completed smoothly.
- Relay protection devices passed all functional tests.
- Customer engineers mastered equipment operation.
- Project commissioning schedule remained on time.
- Customer expressed high satisfaction with both the equipment and technical support.
Why Professional Relay Testing Matters
Reliable relay protection testing helps ensure:
- Safe generator synchronization
- Reliable auxiliary power transfer
- Correct protection operation
- Reduced commissioning risks
- Improved plant reliability
- Compliance with industry testing standards
Professional relay testing equipment combined with experienced technical support can significantly reduce project delays and improve commissioning efficiency.
Related Product
HZJB Six-Phase Relay Protection Tester
Microprocessor Relay Protection Device for 10kV/35kV Substation
Conclusion
This project demonstrates how rapid equipment replacement, professional technical support, and advanced relay testing technology helped complete critical commissioning work at a combined cycle power plant.
The HZJB Six-Phase Relay Protection Tester provided stable performance throughout fast transfer testing, synchronization verification, and relay commissioning, enabling the customer to complete the project safely and efficiently.
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