Explain the concept of reactive power compensation and its role in improving power system voltage stability.

Explain the principles of power system stability and the role of voltage and frequency control in preventing system instability.

Q5- Adjust a fire angle for a three-phase full-wave semi-controlled converter to feed the separately exciter DC motor to get a load torque can be reached to 750 rpm. When the supply voltage of converter is 150 volts per-phase and the absorbed current through the armature 40A with resistance 0.2 a and a constant back emf 0.4v/rpm. Then find the maximum speed for motor assume the previous parameters values are a constant.

The starting winding circuit of a capacitor start, induction run motor consists of a 15 Q resistance and a 20 Q2 inductive reactance. These components are in series with a 50 uF capacitor. The circuit is connected to a 120 V, 60 Hz source. Determine: a. the impedance of the series circuit. b. the current. c. the true power. d. the power factor.

O A CT of nominal ratio 1000/5 A is operating with total secondary impedance 0.4+j0.3 Q. (1 At rated current, the components of primary current associated with the core magnetizing and core-loss effects are respectively 6 A and 1.5 A. The primary winding has four turns and secondary winding has 800 turns. Calculate the ratio error at the rated primary current.

Q8/A three-phase semi converter is used to control the speed of a separately excited d.c. motor rated at 100 kW, 600V, 2000 rpm. The converter is connected to a 3- phase 400 V, 50 Hz supply. The armature resistance is Ra 0.051 ohm and the armature circuit inductance is La = 10 mH. The motor voltage constant is Ke = 0.25 V/rpm. The rated armature current is 100A and the no load current is 10A With the converter operates as a rectifier, and assuming that the motor current is continuous and ripple-free, determine: (a) The no load speed when the firing angles: a= 0° and a= 60°. (b) The firing angle to obtain the rated speed of 2000 rpm at rated motor current.