Energy storage system
Grid Scale ESS
Moving towards the goal of nuclear-free homeland, Taiwan is developing green power actively, along with the installation of energy storage systems (ESS). According to the Forward-Looking Infrastructure Project, the Bureau of Energy, Ministry of Economic Affairs has launched the “Regional ESS Technology Verification Project”. Therefore, Taiwan Power Company (TPC) and Industrial Technology Research Institute (ITRI) have cooperated on developing ESS in Taiwan. ESS can not only smooth green power generation, but also maintain transient stability of regional power grid. In addition to those advantages, it also increases the capacity value of renewable energy and solves the problem of power dispatching. In 2019, We have installed 1MW/1MWh ESS both in Yong-An Kaohsiung and Long-Jing Taichung Solar PV sites. By 2021, another 10MW/10MWh ESS will have been constructed in Zhangbin Changhua Solar PV sites.
The capacity of ESS is 1MWh and takes 780 square meters, can reserves almost 22% of the green power generation from Yong-An PV system. The estimated cost of ESS batteries is about 50 million NTD per MWh, It had successfully connected to power grid by the end of 2018, and operated well. The verification of related functions is still executing now.
Kinmen Energy Storage System
Kinmen is an islanding power system. As renewable energy penetration increase, it’s a possible way to make the power system more reliable by installing energy storage system (ESS). TPRI planned to install two sets of energy storage system in Xia-xing Power Plant for research, helping power system operation and enhancing the knowledge of ESS.
The first phase of ESS(NAS) is 1.8MW rated power and 10.8 MWh storage capacity, which will be constructed before September 2020. The main purpose is to execute load transformation, Increasing diesel engine’s dispatch flexibility. The second phase of ESS(Li) is 2MW rated power and 1 MWh storage capacity. This phase is already interconnected to the grid, carrying out functions like renewable energy smoothing, frequency-watt control, voltage-var control and frequency deviation-P control, provide power system ancillary services and spinning reserve.
Green Energy Smart Management System of TPRI Sulin branch
The green energy smart management system installed in the Sulin branch of Taiwan Power Research Institute(tpri-EMS) was designed base on micro-grid concept. The tpri-EMS is consists of 8 energy management subsystems, including the photovoltaic storage test site. By 2019, the performance test and verification of all-vanadium redox flow batteries and lithium-ion battery energy storage systems have been completed. In the future, the focus will be on the development of application functions of energy storage systems in microgrids, such as peak shaving, load tracking, automatic demand response, reduction of contract capacity as well as photovoltaic smoothing.
Evaluation of all-vanadium flow battery in renewable energy storage
With an aim to increase the ratio of renewable energy to the total power generation to 20% in 2025, Taiwan Power Company has actively been promoting solar power generation and wind power generation. Taiwan Power Research Institute (TPRI) has conducted energy storage demonstration experiments for smoothing renewable energy generation and controlling peak power demand. To successfully achieve these goals, TPRI has introduced an all vanadium redox flow battery’s energy storage system from Sumitomo Electric Industries Ltd. in May 2016. This 125kW/750kWh system was installed at Shulin branch of TPRI in February 2017. In addition, a 250kW/400kWh and a 1.MW/1.5MWh container type lithium-ion battery energy storage system from local company has been constructed in this area in 2019.
Demonstration and experimental study of a flywheel energy storage system for long duration applications
Flywheel Energy Storage System (FESS) stores energy by converting the electricity and the spinning kinetic energy with a bidirectional power conversion device. FESS is suitable for use cases that require hundreds of thousands cycles of charge & discharge. The power output ranges from kW to MW within a short period of 1 second
FESS is one of the oldest energy storage mediums. The performance in terms of energy storage density, energy efficiency, power, and response time of the FESS is outstanding. Using mechanical energy for energy storage has advantages of long cycle life, reliable operation and zero impact to the environment. The energy efficiency of the FESS depends on manufacturing materials, electrical machines, types of bearing, and the vacuum chamber housing the rotor. The State of Charge (SOC) of the FESS can be directly calculated by monitoring the rotational speed of the flywheel which effectively improves the reliability of the power management system
In general, most FESSs can provide high power instantaneously with short duration. However, the FESSs providing the long charge and discharge duration for peak shaving and energy shifting is rare. Therefore, a FESS with rated power of 8kW, discharge duration of 4 hours, and 32 kWh energy has been installed by TPRI in TPC in February 2019. The FESS is tested for various technical characteristics, and the reliability and corresponding performance of the specification have been demonstrated for the reference of application in the future.
To respond to domestic renewable energy development and energy management demand, energy storage equipment, installed by consumers, is a great tool which can be used with demand management and participate in ancillary service, is beneficial to improving power system stability.
To meet the demand of domestic energy storage equipment installation, TPC has scheduled to propose guidelines for grid connection of energy storage system in 2020. A draft were proposed at the end of 2019, and a stakeholders communicate meeting was held on January 8, 2020.
Global Offshore Wind Summit
At the 2019 Global Offshore Wind Summit, Dr. Yuin-Hong Liu, director of the Department of System Planning, illustrated the developments and challenges of power grid in Taiwan.