Influence of distribution voltage control methods on maximum capacity of distributed generators

Recently, the number of distributed generators (DGs) connected to distribution systems has been increasing. It is important to know how large a generator output is permitted when the generators are connected to a distribution system with regulation of the line voltage, the line current, and the power factor of the generator connection point. The authors demonstrate differences of maximum output of the DGs caused by various voltage control systems in a short-length system and a long-length system by load flow calculation. The voltage regulation systems include the following six types: no control equipment, SVC (Static Var Compensator), existing SVR (Step Voltage Regulator), reverse flow type SVR which operates even in reverse flow, existing SVR and SVC, and reverse flow type SVR and SVC. A synchronous generator is considered as a DG in this paper. The calculation results show that the DG's maximum output is about 3300 kW in a short-length system and about 540 kW in a long-length system. However, the DG's maximum output increases to about 3750 kW on installing a SVC, and the SVC's capacity decreases on replacing an existing SVR with a reverse power flow type SVR in the long-length system. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 8–17, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20050