Test and evaluation of energy storage
Test and evaluation of energy storage
The purpose of carrying out the tests of the energy storage has been to get more knowledge of how energy storage with batteries works, to see which ones possibilities and limitations that may exist with the technology. This through to document the basic functions of the energy storage and investigate if the energy storage’s theoretical application areas work cleanly technically. To map and point out which business models seem to be possible to apply to the Swedish market. There are difficulties with that try to imitate other countries’ business models as there are big differences occurs regarding the individual countries’ regulations, incentives, geographical and economic conditions for energy storage.
Participant: Falbygdens Energi AB, Falbygdens Energi Nät AB, Metrum Sweden AB, ABB, Stri AB, and Pöyry SwedPower AB. Project manager: Pia Borg, Sciotech AB.
Falbygdens Energi AB (FEAB) has over the past years conducted research in connection with its energy-storage (lithium ion batteries), which is located in Falköping. The project objectives included testing and evaluation of the existing energy-storage performance. The results from the performed tests of the basic features of the energy-storage can be summarized as:
- Due to the peak shaving function of the energy-storage within the local grid, the main transformer does not need to be over rated to handle occasional peak loads.
- The energy-storage can use reactive power compensation to control the voltage at the connection point to the grid.
- The losses in the main transformer could be slightly reduced by using the energy-storage’s reactive power compensation.
- Internal losses within the energy storage occur in the batteries, inverter, transformer and other ancillary equipment. Losses in the energy-storage are higher when charging the batteries than when discharging. Losses increases when active power is combined with reactive power compensation, i.e. when increasing the total power exchange.
- Measurements on the energy storage batteries indicate that the guaranteed battery capacity should be available after 10 years of service; in other words, the battery capacity decreases as expected.
- The availability of the energy-storage has been 95% over the twelvemonth evaluation period. The downtime was caused by several voltage dips on the upstream network.
- All values related to noise, temperature and magnetic field inside and outside the energy-storage were below the recommended maximum limits.
The energy-storage in Falköping is a prototype delivered by ABB. The energystorage’s rating can be summarized as: storage capacity of 90 kWh energy, 80 kW active power, 100 kVAr reactive power and 50 A harmonics filtering, with a total limit of 100 kVA exchange. The energy storage’s functions can be combined in different ways. The control system is currently not adaptive, which means that the energy- torage does not respond to any events in the grid, but is controlled by a predefined algorithm (time control). Within the project, a control function was developed and tested to control the storage’s charging and discharging. Results from these tests show that:
- The active power of the energy-storage can be controlled based on the frequency of the main grid.
- It is possible to change the active power output direction.
- Fast response time.
- The energy-storage can be used to store electricity and to support the grid at high power levels.
An adaptive control is necessary if the energy storage should be useable in more applications than today. Currently there is however no demand or no simple market for energy storage where you can get paid for improving power quality -, or participate in frequency or power services. Another goal of the project was to evaluate the role that the energy-storage in Falköping might have regarding possible future business models. Some general conclusions are that:
- There is a need to aggregate small-scale energy-storages to be able to participate in a demand response market or frequency regulation market.
- The rules are less complex if a third party player in some cases can mediate services or have their own equipment that includes energy storage.
The business models that are presented in this report are high-level based and generally described. In the project, business model for aggregation, storing of solar electricity and electric car charging stations are investigated. The following models are discussed:
- A model of how different players can work together to aggregate consumer’s flexibility in which energy storages are included.
- A proposal on how a service provider can offer prospective photovoltaic and energy storage owners a ”simple” installation and a ”simple” ownership of the facility.
- Fast charging stations that are owned by a third party player.
In order to achieve some form of profitability, with an investment in an energy-storage, one probably needs to participate in several different markets and sell a variety of energy-storage services. This is possible by using a priority order of the energy-storage’s services. Through multiple revenue streams from a number of players, and basically the same purchasing costs, it will be easier to obtain a profitable investment of the energy-storage.