POWER SYSTEM ANALYSIS AND DESIGN 7TH
EDITION EXAMINATION TEST 2026 QUESTIONS
WITH ANSWERS GRADED A+
◉ Unfortunately we do not live in the world of Platonic ideas . How
does the components in question above behave in reality? Answer:
Voltage Sources:
In reality, voltage sources may have internal resistance and limited
current-carrying capacity.
They can experience voltage drops under load conditions, especially
when supplying high currents.
Voltage sources may exhibit variations in voltage output with changes in
temperature and aging.
Current Sources:
Real-world current sources often have limitations in the maximum and
minimum current they can provide.
Internal resistance can affect the current output, especially under varying
load conditions.
Like voltage sources, current sources may experience variations in
performance due to temperature changes and aging.
Resistors:
,Real resistors have a nominal resistance value, but they also have
tolerances, meaning the actual resistance may deviate from the specified
value.
Resistors may exhibit temperature-dependent resistance changes.
In addition to resistance, real resistors may have parasitic elements like
inductance and capacitance, especially at higher frequencies.
◉ What two principles are used to design an electrical network from the
operational and security of supply perspective? Give an example.
Answer: N-1 Criterion:
Principle: The N-1 criterion is a reliability principle that ensures the
power system can remain operational even if one element (component,
line, transformer, etc.) fails. It states that the system should be designed
and operated to withstand the loss of any single element without
compromising overall reliability.
Example: If a power system has multiple transmission lines connecting
two substations, the N-1 criterion would require that the loss of any one
transmission line should not result in a system-wide failure. If one line
fails, the others must be capable of carrying the load to maintain
reliability.
Redundancy and Diversity:
Principle: Redundancy involves having backup components or paths to
ensure that if one part of the system fails, alternative routes or equipment
can take over. Diversity is the use of different technologies or energy
sources to provide flexibility and resilience.
, Example: In a distribution network, a substation might have redundant
transformers, ensuring that if one transformer fails, the others can handle
the load. Additionally, a network that incorporates diverse energy
sources, such as a mix of conventional and renewable generation, adds
resilience by reducing dependence on a single energy type.
◉ What are the advantages with a large share of hydropower in an
electrical system? Answer: Base Load and Dispatchable Power:
Many hydropower plants can provide a stable and constant output,
serving as a base load power source. Additionally, they offer
dispatchable power, meaning operators can adjust the electricity
generation quickly to respond to changes in demand.
Grid Stability and Reliability:
Hydropower plants can enhance grid stability and reliability due to their
ability to respond rapidly to changes in demand. They can provide
ancillary services like frequency regulation and voltage support, helping
maintain a stable electrical grid.
◉ Describe Sweden's electricity supply , sources, size, properties ,
network topology. Answer: Electricity Sources:
Hydropower: Sweden has a significant share of hydropower in its energy
mix. Hydropower plants harness the energy from rivers and lakes to
generate electricity.
EDITION EXAMINATION TEST 2026 QUESTIONS
WITH ANSWERS GRADED A+
◉ Unfortunately we do not live in the world of Platonic ideas . How
does the components in question above behave in reality? Answer:
Voltage Sources:
In reality, voltage sources may have internal resistance and limited
current-carrying capacity.
They can experience voltage drops under load conditions, especially
when supplying high currents.
Voltage sources may exhibit variations in voltage output with changes in
temperature and aging.
Current Sources:
Real-world current sources often have limitations in the maximum and
minimum current they can provide.
Internal resistance can affect the current output, especially under varying
load conditions.
Like voltage sources, current sources may experience variations in
performance due to temperature changes and aging.
Resistors:
,Real resistors have a nominal resistance value, but they also have
tolerances, meaning the actual resistance may deviate from the specified
value.
Resistors may exhibit temperature-dependent resistance changes.
In addition to resistance, real resistors may have parasitic elements like
inductance and capacitance, especially at higher frequencies.
◉ What two principles are used to design an electrical network from the
operational and security of supply perspective? Give an example.
Answer: N-1 Criterion:
Principle: The N-1 criterion is a reliability principle that ensures the
power system can remain operational even if one element (component,
line, transformer, etc.) fails. It states that the system should be designed
and operated to withstand the loss of any single element without
compromising overall reliability.
Example: If a power system has multiple transmission lines connecting
two substations, the N-1 criterion would require that the loss of any one
transmission line should not result in a system-wide failure. If one line
fails, the others must be capable of carrying the load to maintain
reliability.
Redundancy and Diversity:
Principle: Redundancy involves having backup components or paths to
ensure that if one part of the system fails, alternative routes or equipment
can take over. Diversity is the use of different technologies or energy
sources to provide flexibility and resilience.
, Example: In a distribution network, a substation might have redundant
transformers, ensuring that if one transformer fails, the others can handle
the load. Additionally, a network that incorporates diverse energy
sources, such as a mix of conventional and renewable generation, adds
resilience by reducing dependence on a single energy type.
◉ What are the advantages with a large share of hydropower in an
electrical system? Answer: Base Load and Dispatchable Power:
Many hydropower plants can provide a stable and constant output,
serving as a base load power source. Additionally, they offer
dispatchable power, meaning operators can adjust the electricity
generation quickly to respond to changes in demand.
Grid Stability and Reliability:
Hydropower plants can enhance grid stability and reliability due to their
ability to respond rapidly to changes in demand. They can provide
ancillary services like frequency regulation and voltage support, helping
maintain a stable electrical grid.
◉ Describe Sweden's electricity supply , sources, size, properties ,
network topology. Answer: Electricity Sources:
Hydropower: Sweden has a significant share of hydropower in its energy
mix. Hydropower plants harness the energy from rivers and lakes to
generate electricity.
