Categorized as an intermittent energy, renewable energy sources such as solar power and wind power are affected by the weather, day and night, and the seasons. Thus an energy storage system responsible for power dispatching that is able to maintain the frequency of the power grid at 60Hz is relatively important for a stable supply of power. Taiwan Power Company (TPC) has now joined hands with private enterprises to establish the first energy storage system with power frequency adjustment, which integrates with private energy storage systems to facilitate automatic control in the power grid frequency, and provides 15MW of power in 1 second, with 3-5 times the effectiveness in frequency modulation in contrast to large power generating units.
Abrupt power changes in the past would be dispatched through the centralized power dispatching center with the large power generating units assisting the frequency control, though TPC had hosted a public procurement of the “Ancillary Services in Operating Reserve for Automatic Frequency Control and Frequency Modulation of Energy Storage” for the first time in 2020, which gathered diversified resources and wisdom in energy storage from private sectors that facilitated the efficiency in power grid systems and further improvement in the flexibility of dispatching. The procurement attracted 30 businesses in tender, and will be awarded in July, with 5 manufacturers receiving a total of 15MW of capacity. Energy storage battery suppliers include Tesla, Molicel, Samsung, and other European and American equipment manufacturers.
As explained by TPC, the demand for power is ever changing, and power dispatching not only allows the power generation to be larger than the power consumption, but also maintains the stability in the system frequency by instantly lifting the relevant load during situational changes, including the peak of power consumption amidst summertime, or low solar power generation during sunset, in order to avoid power suspension under an imbalanced system.
The incorporation of private energy storage systems into the ancillary service array resembles a new unit of “virtual power plant”, where these grid-tie energy storage systems are able to intelligently assist the power grid, and release 15MW of power within 1 second by automatically following the 60Hz frequency change from the power system. These energy storage systems are also capable of executing charging and discharging, facilitating instant frequency stabilization, and storing 20,000 Kw of power. TPC will be offering service fees in accordance with the implementation status of the ancillary services, including the detection frequency and response per second for the energy storage system, as well as the automatic feedback of the energy storage system status.
This energy storage ancillary service of TPC will go online by the end of the year at the earliest, and will be providing instantly usable power for power grids nationwide upon incorporation, as well as assisting the established area in stabilizing the voltage, while also helping the existing power generating units to disperse the pressure in dispatching, which facilitates a stable power generation according to the existing schedule.
Ancillary service is one of the emphases of power trading platforms, and the ancillary service platform has been implemented first for experience accumulation purposes. The “Day-Ahead Ancillary Service Market” currently consists of 3 ancillary service items, including “operation reserve for frequency modulation”, “instant operating reserve”, and “supplementary operating reserve”, where the “operating reserve for frequency modulation” requires an instant correction in the frequency deviation of the system, and consists of the shortest response time that is between 1 second and 1 minute, though the requirement in a continuous duration is also shorter. “Supplementary operating reserve” ensures the disposal during a substantial loss of power source derived from incidents of power generating units, thus it is required of a prolonged duration instead of rapid response, whereas the characteristic of “instant operating reserve” lies between the aforementioned two items.
According to the rough estimation of TPC previously, Taiwan still lacks 590MW energy storage systems and 4GW of ancillary services before 2025, and the company has currently planned and configured sufficient ancillary services, with 460MW of energy storage services expecting to be purchased from the industry, where the remaining capacity will be established autonomously by TPC.
(Cover photo source: shutterstock)