Grid codes and testing requirements: What does a power plant operating permit require?

Grid codes provide the foundation for grid code compliance of power plants. Without compliance with grid requirements, a power plant cannot obtain the final operational notice (FON) from the grid operator. Grid codes typically also require testing to ensure compliance with grid requirements before granting the operational notice. The tests evaluate, among other things:

• the power plant’s ability to operate under over- and undervoltage conditions

• the performance of various control modes

• reactive power production and consumption

• active power limitation 

Testing timing and conditions: When is the optimal time to perform grid compliance tests?

The timing for verifying grid compliance is usually determined by the schedule set forth in the grid code, where the deadline for testing is tied to an earlier milestone, such as an interim operational notice (ION). According to grid requirements, some tests must be conducted at a specific threshold power level, which is tied to the power plant’s rated capacity. This dependency on weather conditions, particularly for renewable energy production, makes the testing schedule uncertain and challenging to predict. Generally, spring and autumn are ideal times to test wind power plants due to favourable wind conditions that enable high-power testing. Similarly, solar power plants are mainly tested from spring to early autumn. 

Spring and autumn are excellent times to test wind farms and solar power plants.

Test planning and implementation: How to ensure a smooth testing process

It is recommended to prepare for the tests well in advance. However, the test plan must be submitted to the relevant grid operator in Finland no later than two months before the grid code compliance tests. Ampner coordinates the arrangements for the tests with other relevant parties. Grid code compliance tests are performed when the power plant is fully commissioned and operates with its final control parameter settings. Typically, the tests are completed within a single working day, but testing hybrid power plants may require multiple days due to different power plant sections. During the tests, Ampner can conduct the required measurements using own measurement equipment or coordinate with the equipment supplier if compliant meters are already installed on-site. Ampner has extensive experience conducting grid code compliance tests remotely, which is possible in Finland, for example. 

Test reporting and validation: Final steps in obtaining operating permits

After the tests, the data is processed and compiled into a test report, which is submitted to the grid operator within three months. Raw data is also structured and packaged according to requirements. At this stage, the project’s compliance verification process is in its final phase, with only validation using the PSS/E simulation software remaining. During validation, the simulation model is verified against the measured test data. Once the validation report and clarifications to previously submitted documentation are provided to Fingrid, the grid operator can grant the power plant its final commissioning approval. 

Our main goal is always to obtain the operating permit on schedule.

Comprehensive partnership: Expert support from Ampner – from design to commissioning

Ampner aims to provide its customers with comprehensive services related to power plant design and grid code compliance, from preliminary planning and component selection to testing, modeling, and simulations. The primary goal is always to ensure that the customer receives the final commissioning approval on time. 

Steps for grid code compliance testing and verification:

1. Preparation

• Ensure power plant’s technical readiness for testing
• Plan testing schedule considering weather conditions
• Prepare test plan (to be submitted 2 months before tests)

2. Test implementation

• Coordinate test arrangements with all parties
• Ensure availability and suitability of measurement equipment
• Perform tests within approximately one working day. Hybrid power plant testing takes several days.

3. Documentation and reporting

• Process and analyze test data
• Prepare test report (to be submitted within 3 months)
• Validate simulation model

4. Securing the permit

• Submit validation report and necessary clarifications
• Ensure documentation completeness
• Obtain final operating permit

Contact our experts to ensure smooth progress in your grid code compliance verification project.

The importance of grid requirements is growing

In recent years, battery and solar power plants, as well as hybrid projects combining multiple forms of energy production, have become increasingly common. At the same time, the number of inverter and controller manufacturers has grown. The equipment introduced by new players is often unfamiliar to grid operators, making detailed simulation and verification of power plant functionality essential before granting permission to connect to the grid. 

Finland leads the way in European grid requirements

In Europe, the Finnish transmission system operator Fingrid is a pioneer in the development and implementation of grid codes. In Finland, new grid requirements will be introduced in the coming months, and within the next few years, a European-wide network code is expected. This code will include additional requirements, particularly for grid-forming capabilities in inverter-connected projects. 

How to prepare for new requirements? Expert support ensures smooth project progress

Ampner has been a specialist in verifying grid compliance since 2012. We have led the grid code compliance process for numerous projects across the Nordics and Estonia. Most of the verified power plants have been implemented according to Fingrid’s comprehensive requirements. At the core of our process is power plant modeling, typically conducted in simulation environments such as PSS/E, PSCAD, and DIgSILENT PowerFactory, where the plant’s performance is tested under required operating conditions. Additionally, power plants undergo thorough grid compliance testing, and results are validated against the tests. 

Ampner is well-prepared for tightening grid requirements in many ways. We have invested in resources for simulation and testing to ensure our customers’ projects can be connected to the grid on schedule and in compliance with the requirements. We utilize market-leading simulation tools, including PSS/E, PSCAD, and DIgSILENT PowerFactory. Furthermore, we have addressed increasing simulation demands by acquiring additional software licenses and a high-performance computing system. Our measurement equipment has also been updated to meet the high sampling rate requirements set by most grid operators. 

Ampner is committed to staying at the forefront of new requirements and continuously improving our operations. We are dedicated to ensuring that your power plants, energy storage systems, and even future consumption points meet the increasingly stringent grid requirements. Incorporating grid compliance considerations already in the early stages of a project can significantly streamline its progress – and at Ampner, we are ready to assist, now and in the future.