A new digital power conditioner to improve quality and safety in electrical distribution systems

A new digital power conditioner able to control RMS voltage and short-circuit currents both in a user electrical equipment and a public distribution network is described. The voltage control is obtained without on-load tap changers, by varying the magnetic flux linked to the secondary winding of a special transformer. An original procedure is proposed to manage short circuit situations without power circuit interruptions. Whenever a short circuit occurs, power flow is drastically reduced while the network connection is completely maintained. A digital feedback control system operates a continuous on-line supervision of all subsystems involved by conditioning the relevant electrical quantities under both normal and fault conditions. All control actions are enacted by means of a power electronic device automatically driven by the control system. The results of a thoroughly experimental activity performed on a prototype are also reported. The proposed power conditioner has no limitation either in voltage or power levels.