Wellington — Bruising New Zealand Prime Minister Robert Muldoon is forging ahead with plans for massive energy development now that he has squeaked back into office. Even though his National Party survived a Nov. 28 election by just one seat, Mr. Muldoon is confident about his new three-year term. He has directed planners of the $4 billion energy program to pull out all stops.
The energy plan calls for stepping up production at the Marsden oil refinery, opening a synthetic fuel plant and a new geothermal power station, and constructing an insland oil pipeline. It also calls for expanding the nation's steel plant and for reducing dependence on oil by switching railways from oil to electric power generation on the North Island.
And the prime minister appears confident of taking a fourth term in 1984:
''When the growth strategy projects are well under way and some of them are complete, I think people will see what this election was all about,'' he said recently.
But the new term gives Muldoon many problems as well as a victory. New Zealand's economy is in bad shape. Inflation is running at 15.5 percent. The government's internal deficit is over $2 billion.
Already Muldoon has tabled proposals to increase interest rates. Even before the election, National legislative measures paved the way for a credit squeeze in the new year.
In international affairs, Muldoon's refusal to call off a South African rugby tour of New Zealand put him on shaky footing. The tour was met by demonstrators at every stop along with instances of violence from New Zealanders who oppose South African apartheid and what they believed was New Zealand's contravention of the ''Gleneagles agreement.'' The agreement, among Commonwealth nations, pledges its signers will not participate in sporting events with South Africa as long as apartheid continues there.
The prime minister may have to mend some fences with Commonwealth colleagues. A meeting of Commonwealth government leaders was nearly disrupted by the rugby issue; Muldoon had threatened to raise issues of human-rights violations of Commonwealth members if they raised the rugby issue.
Muldoon's relationship with the Reagan administration, however, appears solid. His right-wing philosophy fits the Reagan mold.
Great store was held by the relationship between Reagan's ambassador in Wellington, H. Munro Browne, and the President when New Zealand's dicey trading relationship with the US was disputed recently.
Muldoon may have to temper his political style to hang onto power in the House of Representatives. One thing in his favor on this issue is the cloud over Wallace Rowling, the Labour Party leader.
Rowling has led Labour through three losing elections. He is highly respected - and this year a rip-roaring campaign nearly gave him victory - but deep divisions within Labour make it unlikely that party will unite behind him another time.
There is no clear successor for Rowling. He is likely to stay on until next year to ensure a smooth transition for his successor.
During an 11-day period after the election when no party had a majority, it appeared the small Social Credit party might win a bargaining position. Resolution of a disputed seat eventually gave National its majority.
For all the questions in New Zealand politics, the impression here is that the narrow margin of seats between the two major parties is good for democracy.