Important Short Questions and Answers: Commitment and Economic Dispatch

COMMITMENT AND ECONOMIC DISPATCH

1. Define economic dispatch problem?

^Ø   The objective of economic dispatch problem is to minimize the operating cost of active power generation.

2. Define incremental cost?

^Ø   The rate of change of fuel cost with active power generation is called incremental cost. The load balance equation , Pg-pd-pl=0.

3. Define base point?

     The present operating point of the system is called base point.

3. Define participation factor?

^Ø   The change in generation required to meet power demand is called as participation factor.

4. Define hydrothermal scheduling problem?

^Ø   The objective is to minimize the thermal generation cost with the constraints of water availability.

5. Define Uncommitment?

^Ø   Commitment of minmum generator to meet the required demand.

6. Define spinning reserve?

^Ø   It is the term describe the total amount of generation availability from all units synchronized on the system.

7. What is meant by scheduled reserve?

^Ø   These include quick start diesel turbine units as well as most hydro units and pumped storage hydro units that can be brought online, synchronized and brought up to full capacity quickly.

8. What are the thermal unit constraint?

^Ø   Minimum up time, minimum down time crew constraints.

10.          Define minimum up time?

^Ø   Once the unit is running, it should not be turned off immediately.

11.            Define minimum down time?

^Ø   Once the unit is decommited, there is a minimum time before it can be recommended.

12.            Define crew constraints?

^Ø   If a plant consist of two (or) more units, all the units cannot be turned on at the same time since there are not enough crew members to attend both units while starting up.

13.            What are the two approaches to treat a thermal unit to operating temperature?

^Ø   The first allow the unit boiler to cool down and then heat backup to operating temperature in time for a scheduled turn on.

^Ø   The second requires that sufficient energy be input to the boiler to just maintain operating temperature.

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

^Ø   Priority list method dynamic programming Lagrange relation

15.            What are the assumptions made in dynamic programming problem?

^Ø   A state consists of an array of units with specified units operating and the rest of the time.

^Ø   The startup cost of a unit is independent of the time it has been offline.

^Ø   There are no costs for shutting down the units.

16.            Define long range hydro scheduling problem?

^Ø The problem involves the long range of water availability and scheduling of reservoir water releases.

^Ø   For an interval of time that depends on the reservoir capacities.

17.            What are the optimization technique for long range hydro scheduling problem?

^Ø   Dynamic programming composite hydraulic simulation methods statistical production cost.

18.            Define short range hydro scheduling problem?

^Ø   It involves the hour by hour scheduling of all generators on a system to achieve minimum production condition for the given time period.

19.            Define system blackout problem?

^Ø   If any event occurs on a system that leaves it operating with limits violated, the event may be followed by a series of further actions that switch other equipment out of service.

^Ø   If the process of cascading failures continues, the entire system of it may completely collapse.

^Ø   This is referred as system blackout.

20.            What is meant by cascading outages?

^Ø   If one of the remaining lines is now too heavily loaded, it may open due to relay action, thereby causing even more load on the remaining lines.

^Ø   This type of process is often termed as cascading outage.