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Automatic Frequency Control (AFC)

This is a frequency regulation service with a unilateral upward response. When the grid frequency drops to the specified frequency, it needs to reach 100% output power within ten seconds to avoid continuous frequency decline.

This is an auxiliary resource with a two-way response. It will automatically detect the grid frequency and complete 100% charging or discharging within one second in accordance with grid conditions. It is divided into dReg0.25 and dReg0.5, and the numbers behind it represent how much the frequency must be maintained within the plus or minus range.

This is a combination of power and energy batteries to form a composite battery, and it is only used for grid-connected energy storage resources. It not only responds to frequency regulations within one second, but also assists in the transfer of peak and off-peak power. It is the best operation scheduling tool to achieve the energy transformation goals of 2025.

Static Regulation Reserve, sReg

Enhanced Dynamic Regulation Reserve, E-dReg

Dynamic Regulation Reserve, dReg

With rich experience in battery energy storage system (Battery Energy Storage System, BESS), Formosa has cooperated with PCS, EMS, and other corporate partners to invest in the construction of energy storage demonstration sites in the Huanhe section of Xizhi District, Baochang section of Xizhi District, Gong-Er section of Linkou District, and several other places. With an aim to hold a total capacity of more than 20MW and provide customers with automatic frequency control (AFC) planning, construction, maintenance, and operation services.

Source of table data: Power Dispatching Office of Taiwan Power Company "Reference Materials of Power Trading Platform - Specifications of Trading Commodity Items in the Current Ancillary Service Market".

Automatic Frequency Control (AFC)

The primary purpose is to leverage the fast charging and discharging capabilities of energy storage systems, allowing them to actively regulate battery charging and discharging in response to supply-demand conditions and frequency fluctuations within the power system. This helps maintain the stability of the power system.


In order to achieve energy transformation, Taiwan’s policy goal is to increase the proportion of renewable energy power generation to 20% by 2025, and the capacity of renewable energy installations such as photovoltaics and offshore wind power must reach a total of more than 27GW. However, solar photovoltaics are affected by the intensity of sunlight, and offshore wind power is also affected by the magnitude of the wind. Neither can provide a stable power supply. The traditional power system will face intermittent and unstable problems caused by the integration of a large amount of renewable energy into the grid. The automatic frequency control (AFC) can immediately discharge and stabilize the frequency when various emergencies cause frequency fluctuations, thus avoiding a greater crisis caused by a collapse of the power grid.

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