Power line carrier for HV networks

摘要

Power Line Carrier (PLC) systems form part of the operational equipment in energy transmission networks. Generally, these systems are either of the traditional analogue type (PLC systems with analogue interfaces) , or digital (with digital inter-faces). It is important to realise that PLC networks are not Internet or broadband telecom carriers for households. They have been developed on the basis of communication standards for power networks and are used to transmit four different types of service: 1. speech 2. data (remote terminal unit data RTU) 3. protection signalling 4. video surveillance. At first, PLC systems were installed in the heart of the transmission grid (e.g. 220 or 500kV). Since then, communications have also been incorporated on lower voltage levels (e.g. 110kV or below). The communication systems for medium voltage differ from those for high voltage. These communications are generally a means of supervising the energy network remotely from the control centre, or of communicating between substations. Within the last two decades, many power utilities in industrialised countries have also set up fibre-optic links.