Load-Dependent Active Thermal Control of Grid-Forming Converters

Grid-forming converters enable an asynchronous connection of grids, which opens new opportunities for the power system management. This includes the potential to control the amplitude and the frequency of the grid voltage to vary the power consumption of the loads and the generation in the grid. Depending on the load sensitivity to voltage and frequency, the power transfer of the grid-forming converter changes. Remarkably, this has an impact on the power semiconductors by means of thermal stress, which is limiting the lifetime of the devices. This article aims to investigate and mitigate the thermal stress in grid-forming converters by applying a load voltage-sensitivity control. Depending on the nature of the loads, their power consumption varies with the voltage. This response is dependent on the connected loads and can be characterized by constant power (independent from the voltage), constant current (linearly dependent on the voltage), and constant impedance behavior (squared-dependent on the voltage). The sensitivity to voltage is exploited to control the load power consumption, reducing the junction temperature fluctuations and, thus, the power semiconductors stress.