Dynamic Modeling and Simulation of a Hybrid Solar Thermal Power Plant

Abstract

A solar thermal power plant presents an environmentally friendly process for producing power. However, due to diurnal and seasonal variations in the availability of solar radiation, as well as uncertainty caused by factors such as cloud cover, efficient operation of a solar thermal power plant is a challenging task. Availability of a dynamic model which represents the process behavior in face of these inevitable variations is a prerequisite for efficiently operating the plant. In this work, we develop a dynamic model for a hybrid solar thermal power plant operating in India. The plant uses two different technologies for solar power collection, namely, a Parabolic Trough Collector (PTC) for heating oil and a Linear Fresnel Reflector (LFR) for generating direct steam. Superheated steam, generated using heat exchangers, drives the turbinegenerator block to generate electricity. The dynamic model is based on first-principles models of various components in the plant, such as PTC, LFR, heat exchangers, and storage tanks, and captures the integrated nature of plant. The model also incorporates heat losses to quantify night time cooling. A preliminary validation of the developed plant model is also presented using routine field data. The model is then used to simulate the dynamic operation of the plant for two case studies: (i) a two day simulation with field solar insolation profiles corresponding to summer days and (ii) a single day case study with cloud cover. The performances of the PTC and LFR fields as well as the overall plant were quantified and compared using various metrics. The case studies involved cold and warm startup scenarios and highlighted the impact of these initial conditions on the plant performance. The proposed dynamic model can be used for designing optimal operation and advanced control strategies.

Solar Collectors Modeling and Controller Design for Solar Thermal Power Plant

“…Parameters for the modeling of LFR are taken from the 1Mwe plant [28], there are a total of eight receiver tubes in the design as shown in equation 2. The dynamics of one receiver tube are modeled and it is assumed that the remaining receiver LFR behaves similarly.…”

“…LFR's first-order model is obtained for the continuous and discrete system by comparing the fitted transfer function of LFR with the steam quality, as shown in equation 7 and in Figure 6 [28]. LFR is simulated using numerical scheme obtained using the chatoorgoon model with time interval 60 seconds as discussed in appendix section A.2.…”

“…In this section, modeling of the Linear Fresnel Reflector (LFR) [28] is discussed for equations (2a)-(3b) of the main article.…”

“…2) HEAT TRANSFER COEFFICIENT IN DSG [28] We now discuss the computation of the convective heat transfer coefficient of the working fluid in LFR (water stream) when it is in: (1) Single phase, (2) Twophase, or is (3) Dry steam.…”

“…h p,1φ = 0.023R 0.8 e P 0.4 r K D a (28) where the Reynolds number and Prandtl number are computed as:…”