Determining Maximum Impedance Limits At A Point of Connection For Different Current Capacity Installations

Abstract

Modern customers use many power electronics based devices that are often sensitive to power quality (PQ) related disturbances. Those devices produce current harmonics that in combination with the network’s impedance at a customer’s point of connection (POC) influence the network’s voltage quality. With a distorted supply voltage, many devices produce more current pollutions. Therefore, the network’s impedance at a POC is quite important and can have significant impact on the network’s power quality. At present some standards specify requirements of the voltage and/or current quality at a POC. However, only few requirements are given for the network’s impedance (short circuit power) which can highly influence the PQ performance at a POC. In this paper, estimation is made to determine the maximum impedance limits at the medium voltage (MV) and the low voltage (LV) customer’s POC. The network operators should be responsible to limit the maximum impedance value at a POC while approving a specific capacity connection to a customer.