Generator Set Synchronization for Parallel Operation Guide

In modern power systems, the parallel operation of generator sets is crucial. Through synchronization, multiple generator sets can maintain consistent voltage, frequency, and phase, enhancing the stability and reliability of the power supply. This synchronization not only optimizes the efficiency of the generator sets but also effectively manages load fluctuations and system faults, ensuring smooth operation of the power network. To achieve this, operators must follow precise steps and monitoring methods to ensure safe and efficient parallel operation. This article outlines the operation process, precautions, and protective mechanisms related to generator set synchronization for parallel operation, helping operators improve their skills and ensure system stability.

Overview of Synchronization

Synchronization is a key step in the parallel operation of generator sets, ensuring that multiple units maintain consistent voltage, frequency, and phase. Achieving synchronization enhances the reliability of the power system and optimizes the overall efficiency of the generator sets. To monitor these essential parameters, operators should use voltage meters, frequency meters, synchronoscopes, and out-of-sync indicators.

Steps for Parallel Operation

Once the generator sets have matched voltage, frequency, and phase, the following steps can be taken for parallel operation.

Close the Load Switch: Choose one generator set and close its load switch to connect it to the busbar. The other generator set should be in a standby state.

Adjust the Speed: Start the standby generator set and begin synchronization. Adjust its speed to bring it close to or equal to the synchronous speed of the running generator (with a frequency difference of no more than half a cycle).

Adjust the Voltage: At the same time, adjust the voltage of the standby generator to match the voltage of the running generator, preparing for parallel operation.

Monitor the Synchronoscope: As the frequency and voltage approach each other, monitor the performance of the synchronoscope:

When the phase is aligned, the synchronoscope needle points to the center, and the indicator light is dim, signaling readiness for synchronization.
When the phase difference is at its maximum, the needle points downward, and the indicator light is bright, indicating that synchronization conditions have not yet been met.

Fine-Tune the Speed: If the needle rotates clockwise, it indicates the standby generator's frequency is too high, requiring a decrease in speed.
If the needle rotates counterclockwise, the speed of the standby generator needs to be increased.

Close the Breaker: When the needle is close to the synchronization point, immediately close the circuit breaker of the standby generator, completing the parallel operation of the two generator sets. After synchronization, disconnect the synchronoscope switch and related synchronization switches.

Precautions

Synchronization is a manual process, and its success heavily relies on the operator's experience. To prevent out-of-sync operations, pay special attention to the following situations before closing the breaker.

Needle Fluctuation: If the synchronoscope needle fluctuates, it may indicate an internal issue preventing accurate reflection of synchronization conditions; do not close the breaker.
Excessive Rotation Speed: If the synchronoscope rotates too quickly, it shows a large frequency difference between the standby and running generators; do not close the breaker to avoid operational risks.
Static Needle: If the needle stops at the synchronization point, closing the breaker may lead to a sudden frequency change, causing it to close at an out-of-sync point; do not close the breaker.

Control of Breakers

Manual Control: Each generator can serve as either the primary or standby unit. During manual synchronization or power supply, operators should use manual breakers.
Automatic Control: Each generator can be designated as a standby or primary unit. Once the primary unit starts, the closing circuit will automatically close to engage synchronization. The standby unit will automatically close and operate in parallel with the primary unit after synchronization.

Fault Protection

Whether the breaker is closed manually or automatically, if the generator set experiences reverse power, low oil pressure, high water temperature, high oil temperature, or overvoltage, the system will automatically trip and disconnect, ensuring the generator is separated from the load to prevent faults from spreading and to safeguard equipment.

Operation of the Synchronization Circuit

Once the generator sets have successfully synchronized, the synchronization circuit will automatically perform a series of monitoring and adjustment operations to maintain ongoing stability and safety. The following outlines the synchronization circuit's workflow.

Busbar Power Detection: When the primary unit closes and sends power to the busbar, the busbar detects its synchronization circuit and sends a signal to the standby unit's synchronization signal.
Automatic Closure of Detection Relay: The synchronization detection relay will automatically close, sending the busbar voltage and standby unit voltage to the synchronization control module.
Automatic Detection of Parallel Conditions: The synchronization control module will automatically check the voltage and speed of the parallel units. If there is a speed difference, the module will automatically adjust the standby unit's speed to meet parallel conditions.
Issuing Closure Commands: Once the synchronization point is reached, the control module will issue a closure command, and the standby unit will execute the closure upon receiving the command, completing the parallel operation of both units.
Exit Work Status: After synchronization, the synchronization circuit will automatically exit the work status. However, the automatic synchronization switch must be manually turned off to prevent the standby unit from receiving parallel signals again during disconnection.

Conclusion

By following these steps and precautions, the operation of generator sets in synchronization for parallel operation can be effectively implemented, ensuring stability and safety in the power system. A well-structured operation process and fault protection mechanisms not only improve the efficiency of generator sets but also extend the lifespan of the equipment, ensuring stable operation under varying loads. Mastering synchronization skills is vital for enhancing the cooperative capabilities and overall performance of generator sets.