Bartosz Olejnik

Earth fault detection and isolation system for MV network

The detection and isolation of short circuits within the MV networks can be improved by the installation of disconnectors together with short-circuit flow passage indicators (FPI) inside the network. The proposed further improvements of FPI operation based on the change of operating criterion to the admittance one and the installation of zero-sequence resistive current forcing system (AWSCz). The operation of such system is analyzed considering the influence of high transition resistances at the place of fault, errors generated within the zero-sequence current measurement systems as well as the poor setting value divisibility of FPI. The proposed decision making system, placed in HV/MV substation, analyses the information obtained from substation measuring systems and from distributed earth fault FPI sensors to issue the proper decision which sectionalizing disconnectors should be open to isolate the faulted line section.

Support the work of Earth fault passage indicator in MV grid

In this paper the issues related to the ability to modernize the neutral point of compensated MV grid and benefits associated with it are presented. In neutral point, one of two ways, introduces an additional voltage source that changes the conditions of the earth fault current and makes it easier to detect. This is particularly important when considering the work of fault current passage indicators. In the article also a new criterion of operation of this type of equipment, based on the estimation of faulty line admittance is proposed. In this paper theoretical analysis of described issues and results of laboratory tests are presented.