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Connecting to the main grid step by step

When a new power plant connects to the main grid, it goes through several steps in the connection process, guided by Fingrid’s Grid Code Specifications for Power Generating Facilities.

In the first phase, the connecting party planning the construction of a power plant, such as a wind power plant, must provide Fingrid with various calculations and technical documentation to prove that the plant meets the technical requirements.

This phase also includes very important simulation models describing the plant’s operation in the event of a change or disturbance in the grid. These models are used to plan the operation of the power system and forthcoming changes.

When the first phase is approved, the power plant is authorised to supply energy to the grid. For example, wind turbines can be commissioned one at a time and connected to production. Official tests are conducted on the completed power plant to demonstrate that the plant meets the key technical system requirements.

Today, commissioning tests are often monitored on Teams: the turbine supplier can operate the plant, the measurement engineer monitors the measurement devices via a remote connection, and Fingrid’s specialists monitor the tests from their offices.

Conversely, synchronous machine power plants – i.e. conventional power plants – are often tested on-site and controlled from the plant’s main control room with Fingrid’s specialists in attendance.

When the tests are complete, the connecting party prepares a report and submits it to Fingrid, along with the final simulation models validated by the tests. Fingrid checks the documentation and models and integrates them into Fingrid’s wide-area grid models.

If the results are acceptable, Fingrid grants the power plant permission to operate. The plant may then supply energy to the grid until further notice. If any changes are made to the plant, they must be approved by Fingrid again.  

A similar connection process is used when power plants connect to a distribution system operator’s network, with one exception: as the network operator at the connecting point, the distribution system operator is also responsible for monitoring compliance with the technical system requirements. Fingrid supports the distribution system operator in work such as modelling and the technical interpretation of the requirements.

Updating requirements and network code

The technical system requirements for power plants and the network code for grid energy storage will be updated in 2024.

“The update will take better account of the technical requirements arising from the growing share of wind power, solar power and grid energy storage,” say Expert Lasse Linnamaa and Specialist Teemu Rissanen from Fingrid.


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