Intelligent transformer substations in modern medium voltage networks as part of “smart grid”

Higher utilization of the power systems, variable load flows due to decentralized power generation from renewable energy sources and a growing need for information of the regulating authorities place higher demands on fault detection and acquisition of system operating data. Furthermore, remote indication and remote control can considerably reduce supply interruption times as well as system breakdown costs, and provide rapid adjustment to varying load conditions. Therefore, the requirements for the intelligence of transformer substations will increase in the future. But where are the limits of useful and cost-efficient utilization? They are somewhere between a merely passive substation and the complete automation. With the gas-insulated medium-voltage switchgear type 8DJH, Siemens offers the basis for application in an intelligent transformer substation. It is optionally equipped with motorised operating mechanism; short-circuit indicators and voltage detecting systems, as well as a variety of other sensors. Plug-connected to a Remote Terminal Unit (RTU) in a separated wall-mounting cabinet, the switchgear fulfills all preconditions for integration in an intelligent network infrastructure. This article provides an overview on different intelligence levels, possible kinds of communication to the telecontrol system as well as necessary components and requirements of future intelligent transformer substations.