power flow

answered Jul 9 '14

jconto
2756 ●10 ●30 ●41

What you want is desirable but not possible. Power flow from a generator gets 'distributed' among all direct branches connected to it. The power flow at these direct branches will get distributed again among the secondary branches connected to these direct branches and so on and so on. The contribution in power from the generator to a particular branch can be calculated using the concept of generator shift factors. Solve the power flow and take note of the generator power output and the power flow at the particular branch. Next, increment the generator output by one MW and solve the load flow and check the new power flow in the particular branch. The delta in power flow at the particular branch is the generator shift factor for that generator on that particular branch. Now, if the generator output increases by 50 MW, multiply it by its 'shift factor' to calculate the incremental power flow at the particular branch. This process assumes a linear relationship when scaling power, not true in a real network. On a related subject, other tools to maintain a desired power flow on a branch is using a phase shift transformer, a back-to-back dc tie, a variable frequency transformer or a UPFC.