Public Broadcasting's new season is really beginning with a bang.
While commercial television has been releasing its new-series balloons over the past few weeks, PBS has been marking time for the most part, waiting patiently until most of the balloons have burst before floating some of its own superseries.
Of all the new commercial TV series so far, the ones with the greatest immediate acceptance seem to be: ''Matt Houston'' (ABC, Sundays, 8-9 p.m.) and ''Square Pegs'' (CBS, Mondays, 8-8:30 p.m.), the only new shows in last week's Nielsen-rated top 20.
Sunday and Tuesday night in most areas of the country should be a time of celebration for TV viewers searching for worthwhile fare. On Sunday, PBS premieres a new ''Masterpiece Theater'' miniseries - To Serve Them All My Days (Sundays 9-10 p.m., but check local listings for premiere and repeats).
Based upon a best-selling novel by R. F. Delderfield, this 13-part drama concerns a Welsh miner's son who returns from World World I to teach upper-class boys in a ''public'' school called Bamfylde (the rough equivalent an American private school). It is a rich and varied mixture of ''Goodbye Mr. Chips'' and ''How Green Was My Valley,'' with just a shading of ''Nicholas Nickleby'' and ''Tea and Sympathy.''
John Duttine was voted best TV actor in Britain in 1981 for his work in this series, in which he grows from embittered, neurotic, unqualified history teacher to a sensitive but supremely confident headmaster. Enroute to the top job, Mr. Duttine, in the role of David Powlett-Jones, reveals a great deal about British social structure in and out of school.
I predict that this BBC-Australian Broadcasting Commission coproduction, adapted by Andrew Davies and produced by Ken Riddington, will prove to be one of the all-time popular hits of ''Masterpiece Theater.'' So, plan for 13 lovely Sunday nights attending Bamfylde, courtesy of WGBH-Boston.
On that same night (this coming Sunday) WNET-New York is launching its own 13 -part series, Nature (8-9 p.m., but check local listings). Hosted by paleoanthropologist Donald Johansen, the first of a three-part opener is called ''The Flight of the Condor,'' based on Dr. Johansen's book of the same name. It is a joyously illustrated lecture on the Andes, focusing not so much on oddities (as was the case of David Attenborough's ''Life On Earth'' in many instances), but on the daily life of the flora and fauna of the area. Unlike the Attenborough series, ''Nature'' doesn't have a thesis such as evolution to prove; it has ''merely'' set out to sample the wonders of the universe by selecting individual examples.
Like life itself, the ''Nature'' series explodes with the excitement of the universe.
And then there is Nova (PBS, Tuesdays, 8-9 p.m., but check local listings), television's best-ever science series. Entering its tenth season, ''Nova'' premieres with ''The Case of the UFOs,'' a curiously fascinating study of the nature of UFO sightings. While most of them are eventually explainable on the basis of current scientific knowledge, the fact is that a great deal is learned about human nature at the same time. In addition, new scientific knowledge is added to our storehouse of information as a side effect.
Future ''Nova'' episodes concern soil erosion in the Himalayas, artificial computer intelligence, and a rerun of one of the most delightfully informative programs of recent years, ''Why Do Birds Sing?''
There's lots more coming from PBS this season - almost enough fine material to make up for the shortage of good shows on commercial TV. Last year PBS had one of its best season's ever, with the quality of its programming hailed by critics and viewers alike. Certainly, if these three new series are any gauge, another super season for PBS can be safely forecast.