Medium Voltage Power Electronics Devices for Distribution Grids

In the last 10 years GCTs (and especially IGCTs) have gained an important market portion in the range of medium voltage applications, mainly for variable speed drive applications, due to their very high power switching capacity. In parallel with thyristor‐based components, transistor‐based devices have also experienced an important evolution toward higher power and voltages since the 1980s. Insulated gate bipolar transistors (IGBTs) were introduced in the 1980s, and were first used in industrial inverters, replacing bipolar transistors. In addition to the series or parallel association of discrete semiconductors as power switching valves, the use of topological solutions can also permit to increase the power and voltage rating of converters for utility applications. Multi‐pulse topologies are based on simple conversion units producing quasisquare‐ wave voltage (known as 6 pulse units), which are combined via phase‐shifting isolation transformers, improving the waveform of the absorbed current and increasing the overall power of the facility.