Investigation and Emulation of Junction Temperature for High-Power IGBT Modules Considering Grid Codes

Grid-connected converters in wind turbine systems play a more active role in the future power grid dispatching for fulfilling specified grid codes. Hence, the diversified demands and faults from grid sides bring more intense thermal fatigue to the power modules. This paper proposes an investigation method for junction temperature (Tj) variation considering grid code constraints in laboratory environment. For the most cases of 690-V wind power systems, an MW-level H-bridge test setup with energy circulation is established. In the case of particular grid code requirements and Tj control strategy, the equivalent voltage and current stresses can be reproduced and applied to the inspected insulated gate bipolar transistor (IGBT) power modules. To investigate the real-time Tj under specific work conditions derived by grid codes, turn-off delay time-based thermal electrical sensitive parameter method is used for Tj estimation. Consequently, a test procedure for the safe operation boundary of power converter using Tj limitation as a new criterion is proposed. Finally, three types of typical operation conditions for a 1.5-MVA power converter are chosen for the validation of the proposed method. The typical conditions under grid code requirements can be reproduced and the corresponding real-time Tj variation can be extracted. With the Tj acknowledge, the safe operation boundary and parameter optimizations of IGBT modules can be determined by real Tj instead of case temperature.