On the Problems of Current Limitations in Networks Based on Power Semiconductor Devices

Abstract

The presence of high short-circuit currents (200–300 kA) in autonomous and generator power systems of low and medium voltage classes, causing a decrease in the switching resource of switching facilities, necessitates the search for ways of limiting the current. The paper proposes a solution to this problem: a semiconductor current-limiting device based on a DC chopper, a DC-to-DC converter. This devices’ features are its low dimensions and losses during typical operation. Semiconductor elements can be arranged quite compactly due to the lack of radiators for cooling, since the cooling process—taking into account the short duration of the current limitation process—is not efficient. The choice of semiconductor devices takes into account the short duration of the current load, as a result of which the temperature of the semiconductor structure does not exceed its permissible value. This paper presents a method for calculating the parameters of semiconductor devices, taking into account the current load as well as adjusting the magnitude of current limitation to a value that can be disconnected by switching devices. The short-term mode of operation of the power semiconductor device with current regulated by the frequency and duty cycle of its operation makes it possible to facilitate the required current limitation in the circuit for the subsequent fault clearance with a typical electrical device. The problem of overcurrent of one of the elements of the limiter is noted, which requires special attention to ensure that the semiconductor device is not overheated. This paper also presents the principle of current limitation, summarizes the results of experimental studies, and analyzes the presented capabilities of a semiconductor current limiter.

Keywords

• short circuit current
• current-limiting device
• autonomous power system
• thermal model
• semiconductor device
• volt-ampere characteristic