A CLOSED-LOOP CONTROLLER FOR VOLTAGE STABILITY

Power system contingencies sometimes cause excessive reactive power im balance even leading to total system breakdown. The problem is usually aggravated when the system is heavily loaded. By closely monitoring t he overloaded lines, it is possible to avoid such major disturbances. A closed loop controller can steer the system to a safer state by resc heduling the generation and shedding the load, if necessary, to allevi ate the overload. This results in a reduction of the risk of total sys tem breakdown. A closed loop controller to this effect is designed. Br oad details of the closed loop controller and its efficacy in avoiding total system breakdown are demonstrated with two examples on a simula ted system.