Faults: Real Power Deficit

•Under normal operation, the power generated by the generators is equal to the load connected and the losses in the power system. PGN = PLOAD  + PLOSS

•Real power is the part of the power which does useful work i.e, the power absorbed by the loads of the power system.

•Real power deficit occur when the supply is less than the demand or loss of generating unit in the grid.

•When real power deficit occurs, frequency levels in the grid starts falling down.

•The rate of falling of the frequency depends on the magnitude of the deficit in the real power. In this case primary frequency control is carried by the generators connected to the grid. Governer mechanism connected to the turbine will try to drive the turbine with rated speed by accepting more fuel. In this manner little frequency deviations (Real Power Deficit) are managed.

In case of still frequency, falling down scenario spinning reserves available at the plant will start delivering power to the grid within few seconds of frequency collapse (mainly Gas turbine plants and hydro plants). If still the demand and supply gap is not taken care of, then load shedding will be followed in the grid by shedding the load of the one part of the power system to maintain the relation between the supply and demand of real power.