Operating Experience with Secured Power Supply Systems Comprising Standby Diesel Driven Generating Sets and Rectifier/Charger Units with Batteries

Different designs of secured or no-break emergency power-supply systems for a.c. or d.c. are in use to ensure continuity of load power in case of mains outages or faults in power generating and distribution systems. Static power supply systems with batteries for energy storage are often supplied by mains or diesel emergency generating sets to tide them over mains outages. This is to reduce the necessary battery stored-energy time; or else to continue operation beyond the installed battery stored-energy time in case of extended faults in primary power supply. With such combinations of diesel standby generators with static secured power supplies, difficulties may occur under certain circumstances by oscillations at generator frequency and power or by harmonic feedback from the rectifiers. Some aspects of these difficulties, and means to overcome them are discussed.