Recent questions tagged power-systems

Consider a power system with $N$ buses, of which $P$ are generator buses and the remaining $Q$ are load buses (where there is no generation).Assume that there are no reac...

The initial three-phase voltage phasors $\left(\bar{V}_{A}, \bar{V}_{B}\right.$, and $\left.\bar{V}_{C}\right)$ at a bus of a power network are as shown in Case-$1$. Due ...

A certain application requires power at a frequency of $16.67$ Hz, while the available grid frequency is $50$ Hz. A $3$-phase synchronous motor connected to the $50$ Hz, ...

The figure shows the single-line diagram of a synchronous generator delivering $P =50 \mathrm{~MW}$ of power at unity power factor to an infinite bus.$I_{S}$ denotes the ...

A single-phase voltage source $v_{s}=325 \sin (2 \pi 50 t) \mathrm{V}$ delivers a current, $i=12 \sin (2 \pi 50 t)+9 \sin (2 \pi 150 t)$ A to a load.The load power factor...

A $220 \mathrm{~V} / 12 \mathrm{~V}$ single-phase transformer is designed for use in India and rated $100$ VA at $50$ Hz. Later, this unit is shipped to the USA where it ...

Three single-phase $11 \mathrm{kV} / 3.3 \mathrm{kV}$ transformers are connected to form a three-phase transformer bank with connections as shown.Considering $\mathbf{A B...

In the circuit shown, the phase currents are\[\begin{array}{l}I_{A}=572.812+j 50.115 \mathrm{~A} \\I_{B}=-254.525-j 459.175 \mathrm{~A} \\I_{C}=-207.083+j 444.091 \mathrm...

The operating characteristic of a reactance relay is given by $X \leq 1 \Omega$, where $X$ is the reactance calculated by the relay. Its operating characteristic in the a...

A three-phase two-winding transformer has a voltage transformation ratio $\frac{V_{P}}{V_{S}}=0.866+j 0.5$, where $V_{P}$ is the primary side voltage in p.u., and $V_{S}$...

For the balanced $3$-phase transmission line shown, consider the following cases:Case-$1:$ $\left|V_{1}\right|=1.1$ p. u.,$\left|V_{2}\right|=0.9$ p. $u ., Z=0.75 \angle ...

A system with two generators $\text{G1}$ and $\text{G2}$ (without generator limits) is shown.The total load on the system is $1184$ MW. The expressions for the cost of ge...

Consider a distribution feeder, with $R / X$ ratio of $5$. At the receiving end, a $350 \: \mathrm{kVA}$ load is connected. The maximum voltage drop will occur from the s...

A symmetrical fault (through a fault impedance of $j 0.007 \mathrm{pu}$ ) occurs at bus $2$. Neglecting pre-fault loading conditions, the voltage at bus $1$, during the f...

The induced emf in a $3.3 \: \mathrm{kV}, 4$ pole, $3$-phase star connected synchronous motor is considered to be equal and in phase with the terminal voltage under no lo...

The transformer connection given in the figure is part of a balanced $3$-phase circuit where the phase sequence is " $a b c$ ". The primary to secondary turns ratio is $2...

In the system shown below, the generator was initially supplying power to the grid. A temporary LLLG bolted fault occurs at $F$ very close to circuit breaker $1$. The cir...

Using shunt capacitors, the power factor of a $3$ -phase, $4 \: \mathrm{ kV}$ induction motor (drawing $390 \: \mathrm{kVA}$ at $0.77$ pf lag ) is to be corrected to $0.8...

Two units, rated at $100 \: \mathrm{MW}$ and $150 \: \mathrm{MW}$, are enabled for economic load dispatch. When the overall incremental cost is $10,000\: \mathrm{Rs}. / \...

​​​​​The figure shows the single line diagram of a 4-bus power network. Branches $b_{1}$, $b_{2}, b_{3}$, and $b_{4}$ have impedances $4 z, z, 2 z$, and $4 z$ per-unit (p...

The incremental cost curves of two generators (Gen $\text{A}$ and Gen $\text{B}$) in a plant supplying a common load are shown in the figure. If the incremental cost of s...

​​​​A $3$-phase, $11 \mathrm{kV}, 10 \mathrm{MVA}$ synchronous generator is connected to an inductive load of power factor $(\sqrt{3} / 2)$ via a lossless line with a per...

​​​​For the three-bus lossless power network shown in the figure, the voltage magnitudes at all the buses are equal to $1$ per unit (pu), and the differences of the volta...

​​​​Which of the following options is/are correct for the Automatic Generation Control (AGC) and Automatic Voltage Regulator (AVR) installed with synchronous generators?A...

In the circuit shown, $Z_{1}=50 \angle-90^{\circ} \Omega$ and $Z_{2}=200 \angle-30^{\circ} \Omega$. It is supplied by a three phase $400 \mathrm{~V}$ source with the phas...

The single line diagram of a lossless system is shown in the figure. The system is operating in steady-state at a stable equilibrium point with the power output of the ge...

For the three-bus power system shown in the figure, the trip signals to the circuit breakers $\text{B}_1$ to $\text{B}_9$ are provided by overcurrent relays $\text{R}_1$ ...

The expressions of fuel cost of two thermal generating units as a function of the respective power generation $P_{G 1}$ and $P_{G 2}$ are given as $F_{1}\left(P_{G 1}\rig...