ACTIVE AND REACTIVE POWER-FLOW FOR MULTIAREA SYSTEMS ON AUTOMATIC-GENERATION CONTROL IN THE PRESENCE OF RAPIDLY CHANGING LOADS

In this paper, the control area dynamics of power systems on automatic generation control are revisited. The role of reactive power flow bet ween regions under automatic generation control is studied by review o f simulations in which the reactive power flow is modelled/not modelle d. The effect of transmission line loading is also studied. Reactive p ower control is accomplished in part by automatic voltage regulation, and reactive power resides in a control ''loop'' much in the same way as active power resides in conventional automatic generation control. An important observation of the analysis is that short term phenomena (e.g., peaks in tie line flow after a load disturbance Delta P + j Del ta Q) require the reactive loop in the model in order to obtain accura te response. Long term phenomena are less sensitive to reactive power modelling. Although these observations are well known qualitatively, e xamples in this paper help to quantify the role of reactive power in p ower flow dynamics. The main lesson learned is that there are cases in which reactive power how must be modelled in order to accurately stud y active power control and flow. An emphasis in the paper is rapidly c hanging, heavy industrial loads. The multiarea case is considered.