Peak load levelling system

Claim 1

Load levelling system for connection to an alternating current network (RST), said system comprising electrochemical direct current energy supply means (1), line-commutated controllable electronic power convertor means (A, B) having DC terminals connected to said energy supply means and AC terminals for connection to said AC network, and continuously controllable reactive power generating means (C, D) connected to said AC terminals, said reactive power generating means comprising a fixed capacitor battery (C) and a line-commutated reactive power convertor (D), the convertor means comprising a first (A) and a second (B) line-commutated thyristor convertor connection, each convertor connection having DC and AC terminals, said convertor connections being series-connected through their DC terminals and having transformer means (TR) connecting their AC terminals, said first convertor connection (A) having a higher rated voltage than the second convertor connection (B), means for setting the control angle of said first convertor connection (A) to either one of two substantially fixed values, corresponding to full direct voltage in rectifying and in inverting operation, respectively, and means for controlling said second convertor connection (B) with a variable control angle.