IEC 61970-302:2024 specifies a Dynamics package which contains part of the CIM to support the exchange of models between software applications that perform analysis of the steady-state stability (small-signal stability) or transient stability of a power system as defined by IEEE / CIGRE, Definition and classification of power system stability IEEE/CIGRE joint task force on stability terms and definitions. The model descriptions in this document provide specifications for each type of dynamic model as well as the information that needs to be included in dynamic case exchanges between planning/study applications. The scope of the CIM Dynamics package specified in this document includes: • standard models: a simplified approach to describing dynamic models, where models representing dynamic behaviour of elements of the power system are contained in predefined libraries of classes which are interconnected in a standard manner. Only the names of the selected elements of the models along with their attributes are needed to describe dynamic behaviour. • proprietary user-defined models: an approach providing users the ability to define the parameters of a dynamic behaviour model representing a vendor or user proprietary device where an explicit description of the model is not provided by this document. The same libraries and standard interconnections are used for both proprietary user-defined models and standard models. The behavioural details of the model are not documented in this document, only the model parameters. • A model to enable exchange of models’ descriptions. This approach can be used to describe user defined and standard models. • A model to enable exchange of simulation results. This second edition cancels and replaces the first edition published in 2018. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) The majority of issues detected in IEC 61970-302:2018 are addressed; b) IEEE 421.5-2016 on Excitation systems is fully covered; c) The IEEE turbine report from 2013 was considered and as a result a number of gas, steam and hydro turbines/governors are added; d) IEC 61400-27-1:2020 on wind turbines is fully incorporated; e) WECC Inverter-Based Resource (IBR) models, Hybrid STATCOM models and storage models are added; f) The user defined models are enhanced with a model which enables modelling of detailed dynamic model; g) A model to enable exchange of simulation results is added; h) The work on the HVDC models is not complete. The HVDC dynamics models are a complex domain in which there are no models that are approved or widely recognised on international level, i.e. there are only project-based models. At this stage IEC 61970-302:2022 only specifies some general classes. However, it is recognised that better coverage of HVDC will require a further edition of this document; i) Models from IEEE 1547-2018 "IEEE Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces" are added. j) Statements have been added to certain figures, tables, schemas, and enumerations throughout the document that indicate that they are reproduced with the permission of the UCA International User Group (UCAIug). These items are derived from the CIM.