Chapter 5, Problem 5.25P

Describe the advancements in high-voltage direct current (HVDC) transmission technology and its applications in long-distance power transmission.

A bipolar HVDC link is delivering 1000 MW at ±400 kV at the receiving end. Calculate the losses in the line, assuming the resistance per conductor as 1 2. Also estimate the sending end power, sending end voltage, power in the middle of the line, and line losses. Ans:=PLosses = 3.75 MW, P,= 1003.75 MW, V401.25 kV, P=1001.562 MW

1/ Power loss due to corona is: a. Inversely proportional to frequency. b. Proportional to frequency. c. Frequency does not effect. d. All these answers are wrong. 2/ We prefer High voltage DC (HVDC) transmission system than High Voltage AC transmission system according to the cost, when: a. The distance of the line is more than B00 km. b. The distance of the line is less than 300 km. c. The distance of the line is equal to 300 km. d. All the above answers are wrong. 3/ HVDC Transmission has lower corona losses than HVAC Transmission because: a. HVDC Transmission tower is less height than HVAC Transmission tower. b. HVDC Transmission system work with zero frequency than HVAC Transmission system of 50 Hz. c. HVDC Transmission currents is uniform distributed in the all cross section of the system conductors than HVAC Transmission due to skin effect. d. All of the above answers are wright.

Describe the role of High-Voltage Direct Current (HVDC) transmission in long-distance power transmission.

Determine the equivalent Pi circuit for the line in Problem 5.14 and compare it with the nominal pi circuit. The following picture shows problem 5.14.

A DC generator of voltage Vg and internal resistance Rg is connected to a lossy transmission line characterised by a resistance per unit length R and a conductance per unit length G. a.)Write the governing voltage and current transmission line eequations. b.)Find the general solutions for v(z) and I(z). c.)Specialise the solutions in part(b) to those for an infinte line. d.)Specialize the solutions in part(b) to those for a finite line of length l that is terminated in a load resistance Rl.

Q4(b) The equivalent circuit of a single phase short transmission line is shown in Figure Q4(b). Here, the total line resistance and inductance are shown as lumped instead of being distributed. i) Sketch the phasor diagram and assess with by labeling the details for the A.C. series circuit shown in Figure Q4(b) for the lagging power factor at load point (Vn). ii) Summarize, what if the load change from low value to high value shown in Figure Q4(b). R XL el Vs Vn Figure Q4(b) Load

Question 5 A sending end bus transfers power through a transmission line of p.u. impedance of 0.1. If the stability margin is 40%. Find the operating power. Assume constant 1.0 p.u. bus voltage at both the ends.

The equivalent circuit of a single phase short transmission line is shown in Figure Q4 (b). Here, the total line resistance and inductance are shown as lumped instead of being distributed. i) Sketch the phasor diagram and assess with by labeling the details for the A.C. series circuit shown in Figure Q4 (b) for the lagging power factor at load point (Vn). ii) Summarize, the impact of voltage regulation and efficiency, if the line resistance and line increases are doubled Figure Q4(b). R XL Vs Vn Figure Q4(b) Load