Independent Voltage Control Research Articles

Design and operation of Huntley station no. 2

Discussion of paper by H. M. Cushing published in the June 1935 issue, pages 632–45, and presented for oral discussion at the power generation session of the summer convention, Ithaca, N. Y., June 25, 1935. C. M. Gilt (Brooklyn Edison Co., Brooklyn, N. Y.): The engineers who designed the Huntley Station No. 2 had the good fortune of being able to make a combined design of distribution system and generating station without having to adapt the station to an existing distribution system. In so doing they were among the first to take advantage of the 2-winding principle which has been used in both generators and transformers. By means of this, circuit breaker current capacities and interrupting ratings are reduced, the need for bus reactors is eliminated or greatly reduced, the reactance between bus sections is high while the normal through reactance from generator to load is kept low. Associated with these advantages are 2 disadvantages, one of which is the fact that there is no independent control of voltage and phase angle of the 2 windings with the result that unequal loadings result in unequal voltages and phase angle differences between bus sections. It is especially important that voltage and phase angle differences be kept small when a low voltage network is fed directly from the generating station busses without intervening feeder regulation. Comparatively small phase angle differences may trip open and cause frequent operation of sensitive network switches on lightly loaded transformers or cause overloads on heavily loaded transformers. The other disadvantage resulting from the 2 winding designs is the impracticability of transferring load from one bus section to another through the transformer (or generator) tying the bus sections together. This condition may result in real loss in station economy if it requires operating units with loadings that differ materially from those giving maximum station economy.