The PS accelerator (Proton-Synchrotron) at CERN (European Organization for Nuclear Research) is composed of one hundred magnets connected in series. During a cycle of 2.4 seconds, the active power at the magnets terminals varies from plus to minus 40 MW. As this large active power variation was not acceptable to the electrical network, a motor-generator set (M-G) was inserted between the grid and the load in 1968. The M-G set acts as a fly-wheel with a stored kinetic energy of 233 MJ and the magnets are fed by two 12-pulse thyristor rectifiers. After forty years of operation, the system has to be replaced. This paper presents a possible solution for a power system based on capacitive storage.