Influences of bottle-necks in the transmission network

Bottle-necks in the transmission network are strongly influencing the net reliability and the cost for transmission. Reliability is reduced because of the more likeliness of shut downs of overloaded transmission lines. Higher cost are coming from the high loaded overhead lines where thermal limit temperatures of 80degC or 90degC or even more can be reached. This thermal transmission losses are increasing the transmission cost significantly. Bottle-necks are also a consequence of increasing power transmission and the too slow upgrade of the transmission network. In some cases the load can reach values which are at the limits of transmission capability of overhead lines, which is at rated currents of about 3000 A. To improve the bottle-neck situation in a transmission network some technical solutions are available like new or upgraded overhead lines, power flow control (FACTS), power factor compensation, additional underground transmission systems (cables and GIL)