Reactive Power Control in AC Power Systems

Electric power systems will be operated in reliable and efficient situation considering reactive power control and voltage stability management. Reactive power margins are related to the voltage stability. The aspects are satisfied by designing and operating of right voltages limits, maximizing utilization of transmission systems and minimizing of reactive power flow. Therefore, controlling reactive power and voltage is one of the major challenges of power system engineering. Reactive power as the dissipated power is affected by capacitive and inductive phenomena that they drop voltage and draw current in the form of heat or waste energy. Reactive power is generated by the capacitors and generators, whereas it is consumed by the inductors and is essential in the parallel connection circuits as power factor controlling and power transmission lines. Reactive power control and voltage stability aspects are effective in reliability of electric power networks. Voltage instability commonly occurs as a result of reactive power deficiency. The trends are to reduce reactive power and increase voltage stability to improve efficiency and operation of power systems. There is a direct relation between reactive power and voltage behavior which serves the voltage collapse and rising effects in power systems. Regulating the reactive power and voltage control should be done according to flexible and fast controlled devices. Placement and adjustment of reactive power play important roles in operation of reactive power compensation and voltage control. Therefore, the operations of reactive power resources in the power systems such as automatic transformer tap changer, synchronous condenser, capacitor banks, capacitance of overhead lines and cables, static VAR compensators and FACTS devices are very significant. Reactive power control and voltage stability management are considered as regional challenges to meet, which otherwise can cause the scale of blackouts increase in the power systems. Theoretical and application issues in these areas help us to identify problems related to reliability and stability of the power systems and prevent the system degradation