Specifics of Power Losses in Power Lines Including Parallel Lines

Abstract Reducing power losses is invested in the trend of combating climate warming. It is necessary to know what parameters of power transmission lines affect the losses in them. In short and medium lines with accounted lumped parameters, the role and influence of the line parameters on losses are visible. In the lines with distributed parameters, at least with one series parameter and one parallel parameter, the role played by them, computing losses in ordinary way as difference between power at line sending and receiving end, is hidden. This is pronounced when considering parallel lines. In two parallel lines the losses can be greater than in a single line. This may occur when the current at the end of the lines is less than the boundary value: the value when two parallel lines and a single line have the same losses. The longer the line and the higher the rated voltage, the stronger the effect. In view of this aspect, it is necessary to know the boundary current. This current can be determined in ordinary way by a series of calculations changing the load value. In some cases, boundary current is affected not only by modulus of the current at the end of the line but also by its angle. It is better to calculate the boundary current by a formula, while studying the role of each parameter.