A closed loop controller for voltage stability

Power system contingencies sometimes cause excessive reactive power imbalance even leading to total system breakdown. The problem is usually aggravated when the system is heavily loaded. By closely monitoring the overloaded lines, it is possible to avoid such major disturbances. A closed loop controller can steer the system to a safer state by rescheduling the generation and shedding the load, if necessary, to alleviate the overload. This results in a reduction of the risk of total system breakdown. A closed loop controller to this effect is designed. Broad details of the closed loop controller and its efficacy in avoiding total system breakdown are demonstrated with two examples on a simulated system. © 1993.