Hopefully you mean the Great Compromise. During the convention their was an argument about whether each state should have an equal number of Representatives or based on a state's population should...
Congress was divided into two houses. The senate (upper house) was seated equally by state; the House of Representatives (lower house) was seated by population.
the plans were made because of the constitutional convention which was a new plan for the government so of course new plans had to be made if they planed to make a new government.