An autonomous distributed VQC method based on Q-TBC

The authors propose a new method, the Q-TBC (Q tie-line bias control) method, for voltage and reactive power (Q) control (VQC). It is developed in the same way as TBC (tie-line bias control) to realize an autonomous and distributed balance of the supply and demand of reactive power in each divided power grid (block). The Q-TBC system in each block controls tap positions, capacitors and reactors based on Q area requirements calculated by local data; this is performed independently but cooperatively with other Q-TBC systems in the next blocks. Q-TBC can not only keep voltage in the trunk transmission system within the adequate range, but can also define the responsibility that should be controlled in each block in order to maintain the voltage of the whole system. In an open market, Q-TBC can be used to obtain the responsibility of reactive power that each block should supply. Computer simulations using the system data of Kansai Electric Power Co. show the effectiveness of the proposed method in voltage control accuracy, reduction in power loss, and flexible control for future ancillary services