Abstract
The integration of wind power plants introduces new dynamics into power systems, forcing reconsiderations of how they are studied, planned, and operated. High quality models are essential to these studies. Manufacturer-specific electromagnetic transient (EMT) wind turbine models are usually available only as black-boxes, which hinders analysis and research. To overcome this issue, this paper proposes a generic EMT-type model for a specific type-IV wind turbine system, which is validated against field measurements from a wind turbine of the same type. More precisely, it proposes a wind turbine model based on an externally excited synchronous generator system connected to a full converter composed of a six-pulse diode rectifier, a dc–dc boost stage and a two-level voltage source converter. The required control features and internal protection schemes are considered and described. Two different fault ride-through control strategies, in line with existing grid codes, are implemented. A corresponding EMT-type hybrid model representation is also developed based on newly proposed switched equivalent circuits and average models for the considered hardware, control, and power electronics stages. It allows for the use of larger simulation time steps, hence considerably improving computation times.
I. INTRODUCTION
OPERATORS of modern power systems have been integrating inverter-based technologies at a fast pace, spurred on recently by the integration of wind turbines [1]. The increased complexity and new dynamics added by this new equipment are forcing reconsiderations in the way power systems are studied, planned and operated, thus yielding the need for more advanced modeling and analysis methods.
As one consequence, the provision of manufacturer-specific electromagnetic transient (EMT) models has already become a requirement for the connection of new generating units in some grid areas [2]. However, due to confidentiality issues, these models are often provided as black-boxes, thus hindering the access to internal control systems and hardware parameters and, therefore, the use of specific analysis techniques.
VIII. CONCLUSIONS
This work proposes a generic EMT-type model for a specific type-IV wind turbine hardware topology. More specifically, the system considers a gearless externally excited synchronous generator and a three-stage full converter composed of a passive rectifier, a dc-dc converter and a two-level VSC.
All main components and controller topologies were developed, characterized and explained. Two different FRT control strategies were implemented, covering a large list of Grid Code requirements worldwide. Moreover, hardware and control protection schemes were also taken into account.
