Thesis (MScEng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: This thesis investigates the credibility of the vanadium redox flow energy storage
system, sometimes termed vanadium redox battery (VRB). The focus is on the
use of this technology in peak-shaving and load-leveling applications. The initial
problem is to find a suitable mathematical model for representing the daily load
profile. A sinusoidal function is identified as an elementary approximation of the
first order. Due to the periodicity characteristics that are inherent in a daily load
profile, the Fast Fourier Transform (FFT) algorithm is identified as a
mathematical model that closely resembles a load profile.
The main theme in this thesis is the determination of an optimal solution during
the peak-shaving process. In this particular context, the optimal solution refers
to the following: With the energy capacity of the VRB and the power rating of the
entire system considered as the constraints, the interest is on (i) the constant
power that the VRB can deliver in order to bring down the maximum demand
quite significantly, (ii) and the time interval in which this constant power is
delivered. Therefore, the VRB power delivered during peak-shaving (PVRB) and
the corresponding time interval are the main two parameters under consideration
in the optimization process.
The mathematical algorithm that can be used to determine suitable values for
these two parameters is developed. Maple" V 5.1 is used for determining the
solution analytically. The obtained results are verified by simulation with Excel".
The investigation into the economic benefits that may be derived from the
utilization of the vanadium energy storage device is also presented. / AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die waarde en toepassing van die vadium "redox" vloei
energie stoorstelsel (VRB). Die fokus is op die gebruik van hierdie tegnologie om
pieklas te verminder en om laste meer egalig te maak. Die aanvanklike probleem is
om 'n geskikte wiskundige model vir die daaglikse las-profiel te kry. Deur gebruik te
maak van sinus-komponente en die toepassing van die Vinnige Fourier Transform
(FFT) is hierdie probleem opgelos.
Die hooftema van hierdie werk is om 'n analitiese oplossing te vind vir die optimale
toepassing van die konsep vir pieklas vermindering. In hierdie konteks verwys die
optimale oplossing na die volgende: Met die gegewe verrnoe van die VRB stelsel en
drywingsvermoe van die kragelektronika is die vrae rondom (i) die konstante drywing
wat die VRB kan lewer om die maksimum aanvraag van die las beduidend te
verminder en (ii) die tydsduur waarin dit plaasvind. Dus is die twee veranderlikes
waarvoor oplossings in die optimale proses gesoek word die drywing (PVRS) en die
tyd-interval daarvan.
Die wiskundige algoritme is met die hulp van Maple® V5.1 ontwikkel. Die resultate is
daarna met behulp van simulasies in Excel® getoets. 'n Analise van die moontlike
ekonomiese voordele is ook ondersoek.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/53276 |
| Date | 04 1900 |
| Creators | Diko, Mpho |
| Contributors | Herman, R., Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 143 p. : ill. |
| Rights | Stellenbosch University |
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