Standardized Impedance: Microgrid Perspective for Inrush Current Compliance

Abstract

With accelerating adoption of non-linear power electronics devices as well as the trend of distributed generation and microgrids, inrush and transient switching currents are not sufficiently limited by standards. The standard reference impedance according IEC 61000-3-3 and IEC 60725 appears higher compared to what is found in practice especially in the present environment resulting in electromagnetic interference challenges with large short term peak currents. This is especially true with complex and isolated power distribution user networks. This paper shows measurements and comparisons of inrush currents for a variety of grid impedance configurations as well as the effects of switching even low wattage power electronic devices. Measurements and simulations suggests lower impedance value of microgrids resulting in higher inrush currents and risking electromagnetic compatibility.

Risk of EMI due to Necessary Modification in a Remote Microgrid in Indonesia

“…Although this peak current is still below the maximum current of all inverters (see Table I), it is important to manage the load distribution since the inverters have different maximum current capabilities. In general, the peak current and its rise time are defined by the source impedance of the supply [10]. Therefore, the microgrid controller plays a critical role because it has to ensure that most of the inrush current is provided by the battery inverters, which have the highest capability.…”