Grid code specifications for power generating facilities

Power generating facilities (‘power plants’) with a rated power output exceeding 0.8 kW connected to the Finnish power system must fulfill the Grid Code Specifications for Power Generating Facilities (‘Specifications’). The requirements are based on the European Network Code (European Commission Regulation 2016/631), to which Fingrid has made national additions and clarifications. The Specifications currently in force are presented in the VJV2018 document and apply not only to the network owned by Fingrid, but also to the power plants connected to the electricity network of the customer, such as the distribution network company (DSO) that is the Relevant Network Operator at given point of connection. The Connecting Party (typically the owner of the power plant being built) is responsible for ensuring that the power plant fulfills at completion and throughout its lifetime the requirements given in the Specifications that have been in force at the time of signing the binding contract for the power plant delivery.

The Specifications for a power plant and the exchange of information related to their verification are determined by the supplied power and voltage of the connection point (category A, B, C, D). Synchronous generators and converter-connected power park modules have their own specific requirements. In addition to the actual technical and operational requirements, the Specifications describe the information to be provided on the installations, the numerical models to be developed for performance verification and the commissioning tests to be carried out for the complete power plant. For larger power plants (type category D; over 30 MW or connection point voltage higher or equal to 110 kV), compliance with the Specifications shall be demonstrated by passing the project-specific verification process which proceeds step by step from design to commissioning in accordance with a specific operational notification procedure.

The Relevant Network Operator supervises the verification of the requirements and is responsible for the exchange of information with the Connecting Party and Fingrid. The Connecting Party must inform the Relevant Network Operator as early as possible of the type of technology planned for the power plant. For example, it is very important to carry out an early assessment of compliance for a generator type that hasn’t been used in Finland previously.

Monitoring the operation of power plants is an important part of the supervision of the power system. Any discrepancies shall be investigated in cooperation between the Connecting Party, the Relevant Network Operator and Fingrid.

Additional documents to Grid code specifications for power generating facilities VJV2018

Utilizing Equivalent Short-Circuit Ratio (ESCR) approach for assessing the slow converter driven stability and tuning the voltage controllers
Concentration of inverter based resources may lead to local stability problems especially when comes to stability of plant level voltage control. Fingrid has published a white paper explaining the technical background and proposed solution. The document can be found here.

Modelling Instruction for PSS/E and PSCAD models to be delivered to Fingrid
The instruction describes structural and functional requirements for PSS/E and PSCAD simulation models to be delivered to Fingrid as a part of the grid compliance monitoring process of C and D type power generating facilities.

Specific study requirements for power park modules related to risk of subsynchronous interaction
The document defines the requirements for protection, modelling, damping and instrumentation arising from the risk of subsynchronous oscillation (SSO) phenomena.

Subsynchronous Oscillation Risk of WPPs Connecting to Finnish Series Compensated Network - White Paper
The document describes the technical background of the SSO phenomena.