This paper proposes a new method to develop a thermal model of an insulated gate bipolar transistor (IGBT) employing an optical fiber sensor mounted on the chip structure. Some features of the sensor such as electromagnetic immunity, small size and fast response time, allow the identification of temperature changes generated by the energy loss during device operation through direct measurement. In fact, this measurement method is considered impossible with conventional sensors. The online monitoring of the junction temperature enables identify the thermal characteristics of the IGBT. The results are used to develop an accurate model to simulate the heat generated during the device conduction and switching processes. The model showed a difference of only 0.3% between measured and simulated results, besides allowing evaluate separately the heat generated by each turn-ON/OFF process.

This paper proposes a control approach and supplementary controllers for the operation of a hybrid stand-alone system composed of a wind generation unit and a conventional generation unit based on synchronous generator (CGU). The proposed controllers allow the islanded or isolated operation of small power systems with predominance of wind generation. As an advantage and a paradigm shift, the DC-link voltage of the wind unit is controlled by means of a conventional synchronous generator connected to the AC grid of the system. Two supplementary controllers, added to a diesel generator (DIG) and to a DC dump load (DL), are proposed to control the DC-link voltage. The wind generation unit operates in V-f control mode and the DIG operates in PQ control mode, which allows the stand-alone system to operate either in wind-diesel (WD) mode or in wind-only (WO) mode. The strong influence of the wind turbine speed variations in the DC-link voltage is mitigated by a low-pass filter added to the speed control loop of the wind turbine. The proposed control approach does not require the use battery bank and ultra-capacitor to control the DC-link voltage in wind generation units based on fully rated converter.

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Summary This paper proposes a novel control approach and supplementary controllers to support the black start of stand‐alone systems with predominance of wind generation based on fully rated converter. The main purpose of the proposed control approach is to provide auxiliary frequency control during the black start of stand‐alone systems. The proposed controllers, based on the signal of the system frequency error, are added to the grid‐side and generator‐side converters of the wind generation unit. One of the supplementary controllers, which act on the speed reference of the wind turbine, aims to extract kinetic energy from the wind turbine. The second supplementary controller aims to temporarily extract additional electrical energy from the DC link capacitor by acting on the typical control loops of the grid‐side converter. The energy extracted from the wind turbine and DC link capacitor is injected into the grid to quickly contribute to the frequency control during the black start of the system. The proposed controllers are coordinately designed by means of a genetic algorithm optimization technique which minimizes the deviations of the frequency and DC link voltage during the controller design process. The proposed operational and control approach has significantly improved the frequency nadir during the restoration process of the stand‐alone system.

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