What are the pros and cons of connecting two AC generators in parallel?

Advantages

• Improve the reliability of power supply systems: Multiple AC generators are connected in parallel to form a power grid, ensuring stable voltage and frequency of power supply, and can withstand the impact of large changes in load.

• Easy Maintenance: Multiple units can be used in parallel, allowing for centralized scheduling and distribution of active and reactive loads, making maintenance and repairs more convenient and timely.

• Economics: Depending on the load size, appropriate numbers of small-capacity units can be invested to reduce fuel and oil waste caused by large-capacity units running at low load.

• Scalability: By installing only the power generation and parallel equipment needed at present, diesel generators can be added later when there is a need to expand the capacity of the power grid. This allows for easy paralleling of expansion units, making the initial investment more economical.

Improving Power Supply Quality: Parallel operation of AC generators can enhance power supply quality because if one generator trips due to a fault, the other parallel generators in the system will share the load, thereby preventing power interruptions caused by the tripping of a single generator.

Disadvantages

• Increased Complexity: Parallel operation requires ensuring that voltage, frequency, and phase are identical, which adds complexity to the system.

• Synchronization Difficulty: Achieving synchronization requires precise control and synchronized devices such as sync lights, relays, or synchronizers.

• High Maintenance Requirements: While parallel operation provides better maintenance convenience, it also demands higher maintenance skills and more complex maintenance procedures.

• Increased Initial Investment : Although parallel operation may be more economical in the long run, the initial investment, including the cost of parallel equipment and synchronizing control systems, may be higher.

In summary, the parallel operation of two AC generators can provide a more reliable power supply, facilitate maintenance and expansion, and in some cases be more economical. However, it also brings about increased system complexity, greater difficulty in synchronization, and the requirement for higher maintenance skills. Therefore, when deciding whether to adopt parallel operation, it is necessary to consider the specific application requirements and budget constraints comprehensively.