EMC Problems in H.V. Substations

The Authors consider EMC problems in H.V.substations in which the protection,measurement and control functions are obtained with up-to date solid-state technologies equipment; the system configuration is typical and includes line and transformer bays. The A.,in order to evaluate the problems in a systematic way,consider.the power system and equipment. in it installed,either if H.V.components or for control and supervision, as components of a system for which the compatibility is to be ensured. The A.examine the main interference sources; for a full diagnostic of environmental situation, the evaluation is extended also for the case of atmospheric perturbations for which the electromagnetic fields and than the transient induced voltages, reach the maximum values. The A.examine`some control methods for reducing the interferences to a level according to the noise immunity of considered control electronic equipment. The interference level shall meet the Enel and international recommendations in case of conventional equipment. In this context the A.point-out the attention on the type of connection to be used between H.V.parts and control equipment,either if control is centralized or not. The A.give experimental results carried out in substations controlled by conventional systems where proper protection were adopted in various interested circuits. The A. evidence problems and possible solutions for protecting computers against conducted and radiated interference. In particular they mention control methods for the screening of control and peripheral rooms, grounding, power supply and interfaces with H.V. and peripheral power equipment. At the end of the paper the A. evidence it is necessary to improve the knowledge of equivalent noise generators applied to circuits of installed equipment; characteristics of generators to be used to verify the reached EMC of equipment are given.