As the dispatcher and operation mode personnel are often faced with the changes and adjustments in operation mode

it is urgent to automatically diagnose the ill-conditioned power flow and calculate the power flow in the adjusted operation mode. For this reason

this paper proposes a set of practical methods to calculate power flow for operation mode adjustment

such as unbalanced power allocation after operation

power flow data checking

power flow initial value setting

automatic identification of ill-conditioned characteristics of power flows

and ill-conditioned power flow automatic adjustment. The properties and size of the attenuation index of voltage amplitude and phase angle during NR iterative process are used to identify the ill-conditioned characteristics of power flows. According to the ill-conditioned characteristics

the automatic adjustment models for ill-conditioned and the unsolvable power flows is developed based on the optimal power flow calculation using the interior point method Realising the power flow calculation for operation mode adjustment of large-scale power systems. The method is used to determine the diagnostic indices and characteristics of ill-conditioned power flow in the IEEE 14-bus system and an actual system

while automatically adjusting the power flow. The results show that the method is correct and effective.