ABSTRACT
This chapter describes the application of newly emerging nanocomposite dielectrics to the electrical insulation of power cables and apparatus, where it has been found that nanocomposite dielectrics are advantageous with respect to a variety of properties compared with the base resins. Amongst these are PD resistance, treeing resistance, short time breakdown strength, space charge free properties, and small arc resistance. They are advanced materials but based on conventional insulating materials such as epoxy resins, polyethylene, polypropylene, polyimide, and silicone rubbers. In that sense, the continuity of technology is smooth and advantageous. Therefore, although nanocomposite dielectrics may be considered to be easily acceptable for replacing conventional insulation, only a few products are on the market. Let us explain the possibility and probability of applying these materials to the power sector.
This section gives a simplified picture of an electric power network from a power generating station down to consumers, as shown in Fig. 15.1. Electric power generators rated at 20 kV class are installed in generator stations to supply electricity downstream through power lines. Power lines consist of overhead power transmission lines (275-500 kV class) and underground cable power transmission and distribution lines. Overhead lines need insulators. Porcelain and glass insulators are in service, but the use of light-weight and mechanically strong polymer insulators is increasing. Extra-high-voltage (150-275 kV class) cable transmission lines are in service in urban areas, while high-voltage (20-30 kV class) and low-voltage (6 kV class) distribution lines operate in residential areas. In some cases, gas insulated power lines (GIL) are utilized. DC submarine cables are sometimes preferred between islands and continents. Power network systems include several stages of substations from high to low voltages. Such substations are driven by switchgear such as gas-insulated switchgear (GIS) and power capacitors. At the consumer level, electric motors are needed for power drive, many of which are driven by inverters. In the near future, smart grid and/or microgrids will emerge with coexisting downstream and upstream power flows. Mixed AC and DC power flows are also envisaged, which requires more reliable electrical insulation materials, such as nanocomposite dielectrics.
