Download Quiz 5 solution - UTK-EECS

ECE 522, Spring 2017 - Quiz 5
Name___________________________
Circle one
1. Based on Lyapunov’s first method, the direct methods for transient stability analysis determine stability
without explicitly solving the DAEs:
True
False
2. Consider an SMIB system subject to a temporary fault. When rotor angle  of the generator reaches its
maximum and is going to return, the rotor speed must be higher than the synchronous speed.
True
False
3. The equal-area criterion is valid for an SMIB system when the system loss is neglected. If loss cannot be
ignored, the accelerating area must be smaller than the decelerating area for a stable system response.
True
False
4. For an SMIB system subject to a temporary short-circuit fault near the generator terminal, how does the
critical clearing angle change when the mechanical power Pm increases
Increase
Decrease
5. Consider a system of two interconnected synchronous machines having
identical inertias, i.e. H1=H2=H. Reduce the system to an equivalent
SMIB system. The inertia of the equivalent machine equals H.
True
False
6. A control method reducing the electrical power output of a generator during a fault can improve its transient
stability
True
False
7. Generally speaking, as long as a multi-machine power system is stable for the first swing following a
disturbance, it must keep its transient stability.
True
False
8. Using integration step t, both the modified Euler method and the 2nd order R-K method have errors on the
order of t3.
True
False
9. The Euler method, Modified Euler method and Backward Euler method all have a weak numerical stability;
with stiff systems, their solutions “blows up” unless a small step size is used.
True
False
1
10. A power system has only one controlling unstable equilibrium point (CUEP), which can be determined from
the power system model and is independent of the fault.
True
False
11. As long as all bus voltages of a power system are maintained close to their normal voltage levels, voltage
collapse will never happen.
True
False
12. A simple radial system has a constant current load supported by a constant voltage source through a
transmission line. The system can be operated at its maximal active power load without voltage collapse.
True
False
The voltage of a constant power load is supported by an
adjustable shunt capacitor. The figure gives the V-Q curves of
the load bus at different load levels and the capacitor
characteristics with different levels of reactive power outputs.
Are these two statements true or false?
13. At loading condition A, if the capacitor is removed, the
system will lose voltage stability.
True
False
14. At loading condition B, if the capacitance of the shunt
capacitor is increased, its actual reactive power injection
into the load bus will decrease.
True
False
2