Energy storage systems can provide backup power for both grid-connected and off-grid operations, often utilizing power switching devices. These devices are among the core components ensuring power supply continuity and reliability. The primary methods include the following:
01
Manual Transfer Switch (MTS)
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When the grid power fails, the energy storage system enters islanding protection mode. Personnel manually disconnect the switch connecting the energy storage system to the grid and then activate the system in off-grid mode (V/F) to provide backup power to the load.
Once the grid is restored, the switch is reclosed, and the energy storage system is adjusted to operate in grid-connected mode (P/Q), resuming power supply to the load.
02
ATS (Automatic Transfer Switch)
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ATS (Automatic Transfer Switch): A dynamic transfer switch is a device used to switch between power sources. In power systems, it is often necessary to connect multiple power sources simultaneously to ensure supply reliability.
ATS is primarily used to automatically switch between the main power source and a backup power source (e.g., an energy storage system, generator, etc.), with a switching time typically ranging from a few seconds to several tens of seconds. When one power source fails or experiences an outage, the ATS can automatically transfer the load to another power source, ensuring continuous power supply.
Regarding the working principle of ATS: after grid power is lost, the energy storage system enters islanding protection mode, and the ATS switches to the backup power source (e.g., a diesel generator, with the grid as the primary source). Once the diesel generator starts running, the energy storage system resumes operation.
03
STS (Static Transfer Switch)
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STS (Static Transfer Switch): A static transfer switch is a device used to switch between power sources. The STS module can intelligently and rapidly separate the grid from the microgrid, switching the power supply circuit with a switching time in the millisecond range.
Under normal grid operation, the load is connected to both the grid and the battery. When the grid fails, the STS disconnects, and the load is powered solely by PV or the battery. Once the grid is restored, the STS reconnects.
Summary
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In practical energy storage systems, ATS and STS can be combined based on specific requirements to achieve higher power supply reliability and flexibility.
Post time: Jul-04-2025