Page 219 - Design of Solar Thermal Power Plants

202 3. GENERAL DESIGN OF A SOLAR THERMAL POWER PLANT

3.7.4 Power Generation Calculation Methods Based on Hourly
Simulation

The key point of this method is that the hourly solar irradiance and
meteorological conditions data are necessary. Through the simulation on
the basis of system energy balance, relationships between the collector
field output and rated input of a steam turbine corresponding to different
concentration field areas can be calculated, so that the annual maximum
generating capacity corresponding to the steam turbine capacity can be
obtained, and the “optimum concentration field area,” thermal storage,
auxiliary boiler capacity, etc. can be determined respectively. The
“optimum concentration field area” refers to the power plant deter-
mined according to the constructed capacity of a certain area. Such
concentration field area configuration intends to maximize the annual
generating capacity of the power plant.
By applying this method, comparing with the design point method,
more abundant information can be obtained, such as energy distribution
among different units of the power plant system under various kinds of
meteorological conditions; logical connection among various units, which
serves as the foundation of power plant DCS preparation; energy flow
and control information flow among various units during power plant
initiation, standby, and stoppage, which are extremely important for
process design. As the design point method corresponds to the typical
hours in a year and typical meteorological conditions, in fact, it is merely
to calculate a “typical point.”
Simulation software that has been broadly applied right now is
TRNSYS, which is capable of analyzing system principles, system
composition, component model, operating mode, operating status,
control logic, etc. In order to facilitate the reader on understanding this
process, principle system of Beijing Badaling Experimental CSP plant at
IEE-CAS has been established in this section and is shown in Fig. 3.48. The
corresponding full system simulation TRNSYS model is shown in
Fig. 3.49.
Simulation model of the system mainly consists of the meteorological
module (Type15-2), heliostat concentration field module (FeffMatx,
Type394), receiver module (CenRec, Type395), high- and low-temperature
thermal storage module (Type 5b, Tank-Type 14) and steam turbine
module of Rankine Cycle (Stage, Type 318), condenser, deaerator, various
kinds of pump and generator modules. This section mainly introduces the
approximate method of system simulation. The specific modeling process
for the mathematical models of the above modules and basic mutual
coupling logics will not be described here.
By applying the HOC (the heliostat optical code of IEE-CAS) software,
as shown in Fig. 3.50, heliostat concentration field of Badaling power plant