Scheduled reserve include quick start diesel turbine units as well as mosthydro units and pumped storage hydro units that can be brought online,synchronized and brought up to full capacity quickly.

10.What are the thermal unit constraints?The thermal unit constraints are

i. Minimum up timeii. Minimum down timeiii. Crew constraints.

11.What are the two approaches to treat a thermal unit to operatingtemperature?

The two approaches to treat a thermal unit to operating temperature aregiven below.

i. Allows the unit boiler to cool down and then heat backup tooperating temperature in time for a scheduled turn on.

ii. Requires that sufficient energy be input to the boiler to just maintainoperating temperature.

12.What are the techniques for the solution of the unit commitment problem?The techniques for the solution of the unit commitment problem are

i. Priority list methodii. Dynamic programmingiii. Lagrange relation

13.What are the assumptions made in dynamic programming problem?The assumptions made in dynamic programming problem are given

below.i. A state consists of an array of units with specified units operating

and the rest of the time.ii. The startup cost of a unit is independent of the time it has been

offline.iii. There are no costs for shutting down the units.

14.Define long range hydro scheduling problem.Long range hydro scheduling problem is defined as the problem involves

the long range of water availability and scheduling of reservoir water releases.For an interval of time that depends on the reservoir capacities.

15.What are the optimization techniques for long range hydro schedulingproblem?

The optimization techniques for long range hydro scheduling problem arei. Dynamic programmingii. Composite hydraulic simulation methodsiii. Statistical production cost.

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16.Define short range hydro scheduling problem.Short range hydro scheduling problem is defined as the hour by hour

scheduling of all generators on a system to achieve minimum productioncondition for the given time period.

17.Define system blackout problem.System blackout problem is defined as the event occurs on a system that

leaves it operating with limits violated; the event may be followed by a series offurther actions that switch other equipment out of service. If the process ofcascading failures continues, the entire system of it may completely collapse.

18.What is meant by cascading outages?Cascading outages are the process if one of the remaining lines is now

too heavily loaded, it may open due to relay action, thereby causing even moreload on the remaining lines.

UNIT-V COMPUTER CONTROL OF POWER SYSTEM

1. What are the functions of control center?The functions of control center are

i. System monitoringii. Contingency analysisiii. Security constrained optimal power flow.

2. What is the function of system monitoring?a. Function of system monitoring is to provide updated information about the

power system.

3. What is SCADA system?SCADA stands for supervisory control and data acquisition system. It

allows a few operators to monitor the generation and high voltage transmissionsystems and to take action to correct overloads.

4. What are the states of power system?The states of power system are

i. Normal stateii. Alert modeiii. Contingency modeiv. Emergency mode.

5. Define normal mode.Normal mode is defined as the mode of operation if the system is in

secure even the occurrence of all possible outages has been simulated thesystem remain secure.

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6. Define alert mode.Alert mode is defined as the mode of operation of the system that it does

not remain in the secure for the occurrence of all possible outages.

7. What are the distribution factors?The distribution factors are

i. Line outage distribution factorii. Generation outage distribution factor.

8. Define state estimation.State estimation is defined as the process of assigning a value to an

unknown system state variable based on measurements from that systemaccording to some criteria.

9. Define maximum likelihood criterion.Maximum likelihood criterion is defined as the problem of maximizing the

probability that estimate the state variable x, is the true value of the state variablevector (i.e, to maximize the P(x) = x).

10.Define weighted least-squares criterion.Weighted least-squares criterion is defined as the problem of minimizing

the sum of the squares of the weighted deviations of the estimatedmeasurements, from the actual measurement.

11.Define minimum variance criterion.Minimum variance criterion is defined as the problem of minimizing the

expected value of the squares of the deviations of the estimated components ofthe state variable vector from the corresponding components of the true statevariable vector.

12.Define must run constraint.Must run constraint is defined as the condition that some units are given a

must run status during certain times of the year for reason of voltage support onthe transmission network.

13.Define fuel constraint.Fuel constrain is defined as the condition if a system in which some units

have limited fuel or else have constraints that require them to burn aspecifiedamount of fuel in a given time.

14.What are the assumptions made in priority list method?The assumptions made in priority list method are

i. No load cost is zeroii. Unit input-output characteristics are linear between zero output and

full loadiii. There are no other restrictions startup cost are affixed amount.

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