Frequency stability in the context of the European Network codes
European network codes take the form of Commission Regulation (EU) and they are published in the Official Journal of the European Union. Of the eight codes we focus on the generation, it is requirements for grid connection of generators (Commission Regulation 216/631). This Regulation divides so called power generating modules into four categories. The category A starts from capacity of 800 W, and these modules must be able not only be connected to the network frequency in the range 47.5 to 51.5 Hz, and even reduce their power at over-frequency. The modules shall to cease active power output after a network operator instruction. For modules with capacity1 MW and more (type B) a synthetic inertia is mentioned. An active power frequency response capability (formerly called primary frequency control) is required for modules with a capacity of over 50 MW (Type C). The respective system operator is entitled to nonsynchronous module C to require providing synthetic inertia during very fast frequency deviations. Performance of modules from B above with regard to the frequency stability and synthetic inertia shell be demonstrated be reports with the simulation results. Dynamic models can be applied to prove power-generating module capabilities and the power-generating facility owner shall produce and provide a validated simulation models.
Knowledge of dynamic models of individual sources (synchronous and non-synchronous) is therefore important and verified models will play a role in the future. The paper describes the various dynamic models of turbines and their governors, as defined in IEC standard (61970-302 CIM for Dynamics specification) and used by transmission system operators of synchronous zone of continental Europe. These are models of steam, water and gas turbines used in synchronous modules. From a total number of 34 models defined in IEC standard in 2013 only halve of them is used, and these can be unified into a few universal models. For this purpose the models are categorized according to the level of detail and the type of control. Then compatible alternatives are found in the MODES network simulator and its Siamese twin DMES, which is used as a simulation engine in the dispatcher training simulator DTS. Characteristics of each model are described using block diagrams and typical parameters. Response performance on simulated changes in the grid frequency and load are presented also for selected types of turbines.