Renewables at >50% in European grids

An industrial sized battery energy storage system (BESS) located in an urban district in Helsinki has provided a research platform for Helen, an energy company in Finland, since summer 2016.

The BESS, rated 1.2 MVA / 600 kWh, was the largest battery energy storage system in Nordic countries at the time of its installation. The BESS is owned by Helen and it is connected to a 10 kV medium voltage network of the local distribution system operator (DSO), Helen Electricity Network. The battery has provided a research platform for several projects including EU-SysFlex.

The purpose of purchasing the battery was to demonstrate the multi-functionality of the battery and its technical capability to provide services to several stakeholders. Helen as an energy company and aggregator pursues the BESS for the smart grid integration, ancillary markets and development of customer services. For the Finnish transmission system operator (TSO) Fingrid, the battery can provide power system frequency control. A local DSO can utilize the services of the battery for the control of reactive power and voltage, demand response and peak shaving functionality.

The battery provides a research platform for the Finnish demonstration of EU-SysFlex, which investigates how small distributed flexible assets connected to medium and low voltage levels can be aggregated to bigger entities and traded on the TSO ancillary service markets. On the other hand, the Finnish demonstration aims to a technical proof of concept for a DSO reactive power market. During the first two years of the EU-SysFlex project, Helen has tested frequency control as well as reactive power compensation capabilities of the battery.

During the research phase, it was observed that the control capability of the battery is hard to manage. If the battery goes empty or full it will be unable to fullfill the control requests. It is already known that the battery cannot provide frequency control continuously without reaching the limits of its capacity. However, the reliability of delivery can be improved if other resources are combined to the bid left e.g. to the FCR-N (frequency containment reserve for normal operation) market. In this way, the shortages of the battery could be compensated. The other option would be to add forecasting to the systems and predict the availability of the BESS to operate on the TSO ancillary markets.

In EU-SysFlex, Helen and VTT (Technical Research Centre of Finland) are developing a set of forecasting tools to help an aggregator to determine the bid sizes on the ancillary markets and avoid penalties occurring in the case of failure to deliver. As a part of the Finnish demonstration, the BESS will also be used as a resource for the proof of concept of a DSO reactive power market.

After gaining the valuable knowledge and experiences from the research and testing phases, it is time to start the business operation on the TSO ancillary markets. Helen is currently connecting the BESS to its aggregation platform with the target to start operation in the FCR-N market. In addition to the research and business operations, the BESS has a role in Helen’s product and service development.

Figure 1: The battery energy storage system in Suvilahti, Helsinki. The battery is connected to the same medium voltage connection point with a nearby PV power plant and EV charging stations. Photo: Helen Ltd.


Written by: Suvi Takala, Kristiina Siilin (Helen Ltd.) and Pirjo Heine (Helen Electricity Network Ltd.)


Helen Ltd. helps to make everyday life a little easier for almost 500,000 customers in Finland. In addition to heat, cooling and electricity, we offer solutions for regional and renewable energy, smart buildings and electric transport. We are developing a smarter, carbon-neutral energy system that enables everyone to produce, use and save energy with respect for the environment. We aim to achieve 100 % carbon neutrality in our energy production by 2035. Helen Ltd. is owned by the City of Helsinki and we are one of the largest energy companies in Finland.

Helen Electricity Network Ltd. concentrates on electricity network operations and provides transmission and distribution services to its customers. We are the licensed distribution system operator in Helsinki and a part of the Helen Group. The reliability of supply is outstanding with the mainly underground cable network.

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Disclaimer: blog entries reflect individual views of the author(s) that may not reflect official positions or communication of the project / project consortium.


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