Page 42 - Mathematical Models and Algorithms for Power System Optimization

32 Chapter 2

(6) Unit start and stop control card (GS), including GS identification, area name, power plant
name, unit name, unit type (1 for thermal power or nuclear power, 2 for hydropower,
3 for purchased power), and including upper and lower limits of unit output (MW), unit
starting and stopping time (hour), and unit start and stop state (0 for stop, 1 for start, 1 for
maintenance) in five time periods within one day, respectively.
(7) Unit start and stop cost parameter card (GY), including GY identification, area name,
power plant name, unit name, unit starting time (hour), unit stopping time (hour) in five
time periods, respectively, unit cost (yuan/MWh), and unit fixed cost (yuan/MWh).
(8) Comment card (**), excluding data involved in optimization calculation; comments can
be added after ** to make data files readable, including ** identification and note
information.

2.5.3 Special Settings to Meet the Calculation Requirements

Whenever the formulation of a mathematical model has been developed, it is just for some
purposes. However data is changeable, and some expected results can be reached by settings of
input data without the need to develop some special or new model. The details are shown as
follows:

(1) If some power plants are needed to operate with a base load or at a given output in certain
time periods, the lower and upper limits of the generated output for power plants,
whether hydropower plants or thermal power plant, will be set to be equal or almost equal
to each other at a certain time period; then the optimization model can automatically make
the plant undertake the base load in different time periods. Thus, the constraints of
generated output and generated energy can also be dealt with for all power plants in this
way, so power plants with different property rights can fulfill the amount of generated
energy specified in the agreement.
(2) If some units are needed to satisfy some special operation conditions, for example, for
peak load regulating in a specific time period, different cost coefficients can be set for each
unit in different time periods, that is, with different prices for peak and valley load.
Then, each unit can automatically either generate power or purchase power by setting
different cost coefficients in different time periods.
(3) If a pumped storage plant is needed to meet the changing requirement of a reservoir water
level, the water quantity constraints can be set to automatically control the operation
condition of the pumped storage plant.
(4) If a pumped storage plant is needed to avoid operating both in generating and pumping
states at the same time, the load difference can be used as indexes of operation states.
The time period when load is larger than an average load is set as a generating state, and
the time period when load is smaller than an average load is set as a pumping state, so that