House and Senate conferees, abandoning attempts to resolve a delicate issue of spending self-discipline, agreed yesterday to a $547.6 billion budget for fiscal 1980 that goes partway toward meeting Senate demands for higher defense spending.

The conferees' agreement came a month after the start of the fiscal year, delayed by long hassles over both spending priorites and the still unresolved issue of whether congressional committees should be forced to cut spending to meet previously established budget goals.

The agreement must still be approved by House and Senate. How they resolve the self-disciplining issue could provide a major test of how seriously Congress takes its five-year old budget process, although the process itself is not considered in jeopardy.

To settle spending priorities, conferees from the Senate and House Budget committees agreed on compromises worked out in private by the two chair men, Rep. Robert N. Giaimo (D-Conn.) and Sen. Edmund S. Muskie (D-Maine).

While the conferees agreed to the Senate's $141.2 billion in defense budget authority, they trimmed the Senate's proposed defense outlays from $130.6 billion to $129.9 billion. The Senate, embroiled in controversy over the pending strategic arms limitation treaty with the Soviet Union, was demanding a 3 percent increase in defense spending in line with President Carter's 3 percent pledge to North Atlantic Treaty Organization. The House had wanted defense spending of $128.6 billion.

Domestic spending was also settled by compromise, with the House winning some gains for social programs.

The projected budget deficit is $29.8 billion, barely squeaking under the psychological barrier of $30 billion and roughly equalling the 1979 deficit, recently calculated by the administration at $29 billion deficit that Congress set as a target last spring.

It was to help close the widening deficit, which was caused largely by inflation, economic slow down and rising energy prices, that the Senate Budget Committee last summer proposed to resort to a little-used budget disciplinary procedure known as "reconciliation."

When Congress adopted its 1974 budget act in the midst of its spending scraps with the Nixon administration, the idea was to gain more legislative control over the nation's spending -- both the size of the budget pie and how it is sliced. Through new Budget committees, Congress early in each session would set spending targets, with sub-ceilings for every category of the budget. Final ceilings would be set later, allowing for adjustments in economic conditions. Authorizing and Appropriations committees would be expected to adhere to the limits.

Among the self-disciplining devices was "reconciliation," under which Congress could direct its committees to slash previously approved spending to reduce budget overruns and meet spending targets.

But, while the Senate voted overwhelmingly to use it, the House has balked, under strong opposition from its committee chairmen. Giaimo, noting that the House version of the budget resolution was rejected once and then passed by only six votes, said at one point during the conference that the House conferees would "literally get shot out of the water" if they tried to order House committees around.

As a result, the conferees agreed to disagree on that one issue. After the Senate approves the budget resolution including reconciliation, the House conferees will ask the House to approve it minus reconcilation.

At the point, the Senate will have to either go along or go back to conference. Conference committee sources said yesterday they expect the Senate to go along. If it does, any appropriations that exceed the budget limit could be in jeopardy. Or, as some committee members believe, yet another budget resolution may be required to accommodate further economic shifts and possibly a tax cut, creating an opportunity for Congress to wiggle out of any appropriations squeeze.