We sincerely appreciate the support of the Engine Room Simulator Lab(Wartsila Techsim type), at the DITEN Department of the University of Genoa(UNIGE) for providing the foundational information and simulator screenshots for this article. Originally developed for educational use within the Maritime Science and Technology program, this article aims to contribute to the advancement of maritime training and knowledge.
Generator synchronization on ships is the process of matching the electrical parameters—such as voltage, frequency, and phase—of two or more generators before connecting them to a common bus bar. This enables the generators to operate in parallel and share the load efficiently. Synchronization is a critical procedure to ensure the stability and proper operation of the ship’s electrical system, as improper synchronization can lead to severe consequences, including mechanical stress, electrical faults, and damage to the generators and other connected equipment.
Typically, this process is carried out automatically using advanced synchronization systems that monitor and adjust the parameters in real-time. However, a manual synchronization panel is also provided as a backup to address emergencies, such as automation failures, power outages, or blackouts. The manual panel allows trained personnel to synchronize the generators by carefully monitoring instruments and making precise adjustments, ensuring continuity of power supply even in critical situations. This dual approach—combining automated systems with manual intervention—enhances the reliability and safety of the ship’s electrical network.
Here’s how the process works and why it’s essential:
Key Parameters for Synchronization
To synchronize generators, the following electrical parameters must be matched:
- Voltage: The voltage of the incoming generator must match the voltage of the generator already connected to the system.
- Frequency: The frequency (measured in Hertz, Hz) must be the same, typically 50 or 60 Hz depending on the ship’s electrical system.
- 1Phase Angle: The phase angle between the voltage waveforms of the generators must be synchronized, meaning they should reach their peak and trough points at the same time.
- 3.2 Phase Sequence: The phase sequence of the generators must be the same. This refers to the order in which the phases (in a three-phase system) reach their maximum values.
Why Synchronization is Important:
Load Sharing: Synchronizing generators ensures that multiple generators can share the electrical load efficiently. This avoids overloading a single generator, which can lead to overheating and failure.
System Stability: Proper synchronization keeps the electrical system stable and prevents fluctuations in power that can damage sensitive equipment on board.
Safety: Unsynchronized generators can cause severe electrical faults, resulting in damage to the generators, switchboards, or even causing fires due to electrical surges.
Steps Involved in Synchronization:
- Adjust Generator Speed: The speed of the prime mover (such as the diesel engine driving the generator) is adjusted to match the frequency of the generator already online.
- Voltage Matching: The voltage output of the incoming generator is adjusted using voltage regulators to ensure it matches the existing generator.
- Phase Matching: The phase angle is monitored using a synchroscope or a set of indicator lamps, and adjustments are made to bring the phases into alignment.
- Closing the Breaker: Once the parameters are aligned, the circuit breaker is closed, allowing the incoming generator to connect to the system and share the load.
Credit: https://marineinbox.com/marine-exams/alternator-synchronization/
Tools Used for Synchronization:
- Synchroscope: An instrument that visually indicates the phase difference between the generators.
- Synchronization Lamps: These are lights that indicate whether the generators are in phase or out of phase. When the lamps are dim, it indicates the generators are in phase and can be connected.
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Synchronization Process
Synchronization is the procedure of matching the voltage, frequency, phase angle, phase sequence, and waveform of one generator with another or with the grid. Synchronization is a multi-faceted procedure aimed at unifying the voltage, frequency, phase angle, phase sequence, and waveform across generators or between a generator and the grid. This alignment is paramount for several reasons:
– Voltage and Frequency Matching: Ensures a seamless power supply by aligning the output of all generators.
– Preventing Transient Phenomena: Minimizes voltage dips, surges, or frequency deviations during the synchronization process.
– Enhancing Grid Stability: In scenarios where ship generators are synced with a grid, synchronization supports the overall stability and reliability of the electrical supply.
The process involves several critical steps:
- Voltage Matching: Adjusting the generator’s output voltage to match the grid or reference generator.
- Frequency Matching: Aligning the generator’s frequency with that of the grid or another generator using speed control mechanisms.
- Phase Synchronization: Adjusting the phase angle to ensure it matches, often utilizing synchronizing devices like relays or synchroscopes.
- Circuit Breaker Closure: Once alignment in voltage, frequency, and phase is achieved, the generator is connected to the grid or other generators, beginning its power supply.
The above image, titled “Synchro Panel,” shows the control interface for managing generators on a ship. It includes various gauges, meters, and controls that are essential for monitoring and managing electrical power generation. Some key features of the synchro panel include:
- ACB (Air Circuit Breaker) Control Switches: These are used to open and close the circuit breakers, which control the flow of electricity from the generators.
- Generator Control and Monitoring: The gauges indicate important parameters such as kilowatts (kW), which measure power output, and other gauges for monitoring voltage and frequency.
- Auto Synchronizing and Load Sharing: Knobs and controls for auto synchronizing the generators and shifting load between them to ensure balanced power distribution and efficient operation.
- Engine Control: There are switches for starting and stopping the diesel generators (DG1 and DG2), along with emergency controls and indicators for electrical faults.
Load Sharing and Its Significance
Beyond the mechanical act of synchronization, the principle of load sharing holds equal significance, ensuring that the electrical burden is equitably distributed amongst the generators. This not only optimizes their usage, preventing individual generator overload, but also bolsters fuel efficiency and bolsters operational dependability. Load sharing brings with it the added advantage of redundancy, permitting other generators to compensate smoothly and maintain continuity in the event of a generator outage.
Load sharing encompasses measuring the load on each generator and adjusting their output to achieve an even distribution. This involves:
- Load Measurement and Adjustment: Using sensors to monitor load and controllers to adjust the generator’s output accordingly.
- Continuous Monitoring: Keeping track of the load distribution in real-time and making necessary adjustments to maintain the desired balance.
Consequences of Poor Synchronization:
- Voltage Imbalance: If voltage levels are not matched, it can cause the generators to overload or produce uneven power distribution, damaging equipment.
- Frequency Difference: If frequencies are not aligned, it can result in mechanical stress on the generators and connected machinery.
- Phase Mismatch: A phase angle mismatch can cause large electrical currents to surge through the system, damaging both the generators and electrical components.
In summary, generator synchronization on ships is essential for maintaining the stability of the electrical system, ensuring safety, and preventing equipment damage. Proper training and careful execution of this procedure are critical for marine engineers and crew.
The synchronization and load sharing of generators on ships are crucial for ensuring efficient, reliable, and safe electrical power supply. These processes not only optimize generator use but also enhance the overall stability of the ship’s electrical system, contributing significantly to the seamless operation of maritime vessels.
By: R. Karimpour, Ph.D
For more information please also follow below section:
https://www.youtube.com/watch?v=uVTyzsCFE6I
Frequently asked questions with the answers:
1. How Are Generators Synchronized on a Ship?
Generator synchronization on ships is the process of matching the voltage, frequency, and phase sequence of a generator (incoming) with the running system (busbar) before connecting them. This ensures that the generators work together without causing electrical faults or instability.
The steps involved in synchronizing a generator include:
- Matching Frequency – The incoming generator’s frequency must be adjusted to match the running generator(s).
- Matching Voltage – The generator’s output voltage must be equal to the system voltage.
- Matching Phase Sequence – The phase sequence of the incoming generator must align with the running generator(s).
- Minimizing Phase Angle Difference – The phase angle between the generators should be close to zero before synchronization.
Once these parameters are matched, the synchronizing switch (breaker) is closed, allowing the generator to be connected to the power grid.
2. What is Synchronization in a Generator?
Synchronization in a generator refers to the process of matching electrical characteristics (voltage, frequency, and phase) of an incoming generator with those of a running system before connecting them together.
Synchronization is essential for:
- Preventing power surges and instability
- Ensuring smooth load-sharing between generators
- Avoiding mechanical and electrical damage
- Maintaining steady power supply on ships
Improper synchronization can cause power fluctuations, generator damage, and blackout risks.
3. What Are the Three Methods in Synchronizing a Generator?
There are three main methods used for generator synchronization:
1. Three Dark Lamp Method
- Three lamps are connected between the phases of the incoming generator and the running system.
- If all three lamps turn dark simultaneously, it indicates that voltage and phase angles are correctly matched, and synchronization can be performed.
- If lamps flicker, adjustments must be made before synchronization.
2. Two Bright, One Dark Method
- Two lamps appear bright while the third one remains dark.
- The dark lamp indicates that synchronization is achieved at the right phase sequence and voltage.
3. Synchroscope Method
- A synchroscope (electromechanical device) is used to monitor phase difference and frequency.
- The pointer on the synchroscope rotates and should be aligned at the zero position before closing the circuit breaker.
- This is the most precise and modern method used on ships today.
Each method has its advantages and limitations, but modern ships primarily use synchroscopes for accuracy and safety.
4. What is Paralleling of Generators in a Ship?
Paralleling of generators is the process of running multiple generators simultaneously to share the electrical load of a ship. This ensures:
- Optimal fuel efficiency (reducing excess fuel consumption)
- Balanced power distribution (avoiding overloading of a single generator)
- Redundancy and backup power in case of generator failure
Paralleling also allows engineers to adjust power generation based on the ship’s demand, improving operational efficiency.
5. What Are the Three Conditions for Synchronization or Paralleling of Generators?
For successful synchronization and paralleling of generators, three main conditions must be met:
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Voltage Matching
- The voltage of the incoming generator must be equal to the busbar voltage.
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Frequency Matching
- The frequency of the incoming generator should match the running generator’s frequency to avoid surges.
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Phase Sequence Matching
- The phase sequence of the incoming generator must be the same as the running system.
Additionally, the phase angle difference should be as close to zero as possible before synchronization to prevent power transients.
Generator synchronization is an essential electrical operation on ships, ensuring stable power distribution and efficient fuel consumption. Understanding methods, conditions, and best practices helps marine engineers, officers, and electrical personnel manage ship power systems effectively. By following SOLAS guidelines and industry best practices, ship operators can ensure safe and efficient generator synchronization, minimizing risks and maximizing performance.