FREE Bachelor of Electrical Engineering Power System Questions and Answers
A power system's fault is _____ if all of the sequence voltages at the fault spot are equal.
LLG faults are one of the possible fault types that can occur in a power system. They involve a fault between two phases (Line-Line) with a connection to ground (Ground). Analyzing the behavior and effects of different types of faults is essential in power system protection and stability studies.
The entire protection is what a protection system engineer intends to offer; he can accomplish this via .
Three phase fault relays and two earth fault relays can be used to completely protect the power system and cover the whole operational zone.
If the receiving end voltage is Vr0 and the power system network is at Vs, then the impedance of the TL is (R+j5). The ideal resistance value for maximum power transfer to the load should be .
The formula for greatest power transmission is:
X=√3 R
3=√3 R
R=√3
A power system with 200 buses has 160 PQ buses. The minimal number of simultaneous equations that must be solved in order to arrive at a load flow solution using N-R in polar coordinates is .
Total buses are 200, PQ buses are 160, PV buses are 200-160, Slack buses are 1, and the total number of equations is (40-1)*1 + (160*2) = 359.
Which of the following does a hydroelectric power plant not have to its advantage?
These plants' output is seldom consistent. This is a result of their reliance on the river's seasonal flow rate of water. The benefits of hydroelectric power plants include no standby losses, low operating costs, and no need for fuel.
The power system's voltage regulation is .
VR is the increase in voltage for a transmission line at the receiving end.
The zero and maximum regulation points for a particular power system will be at the impedance angle of
ZVR and maximum VR are equal at At θ=45° .
A power system can handle up to 15 MW of load. 50% of the annual load factor. If the plant capacity factor is 40%, the reserve capacity of the plant is .
LF = Average Demand/Maximum Demand = 0.5 Plant Capacity Factor = Average Load/Plant Capacity = 0.5/0.4 Plant Capacity*15 = 18.75 MW Reserve Capacity = 18.75-15 = 3.75 MW.
A single line does not adequately represent:
A single line diagram shows a balanced power system on a phase-by-phase basis with the neutral removed. In a single line diagram, the neutral wire is not visible. Alongside the transformer symbol with its impedance and rating, winding connections (star or neutral) are shown.
Which of the following power systems can have a single line diagram?
A single line diagram can only depict a balanced power system. A single line diagram is created for each phase. An unbalanced power system caused by LLG, LG, and LL faults cannot be represented on a per-phase basis.
Which of the following does the reactance diagram from the impedance diagram not take into account?
By using a symmetrical network of different power system components, a reactance diagram is created without taking into account the resistance of the individual components, static loads like induction motors, or the shunt component of transformers.
The load curve's area under the curve is an indication of
A load curve is created by graphing a fluctuating load while retaining time and the load on different axes. The total number of units produced over a specific period of time is represented by the area under the load curve.
80 percent of a 50 bus power system is sparse (Ybus). There will be __________ transmission lines in total.
Number of TL = (500-50)/2 = 225 transmission lines; Number of non-zero elements: 50*50*20/100 = 500 non-zero.
A big power system network's _______ is shown in the provided graph.
A abrupt dip in the voltage profile caused by an LG failure will be quickly recovered.
Which of the following is not necessary for choosing a hydroelectric power plant's location?
The reservoir's ability to store water may be reduced by sedimentation, which may also harm the turbine blades. The key criteria for choosing a hydroelectric power plant site include the availability of water, a sizable catchment area, and rocky terrain.
If a power system has __________, it will operate with greater flexibility.
The system will be more adaptable if different types of power plants are operated in tandem. For example, steam and nuclear power plants will supply base loads, hydroelectric power plants will supply base or peak loads depending on water availability, gas turbine power plants will meet peak load demand, and existing diesel power plants will only run in emergencies.