Solar array emulator

Date
2016-12
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: A typical photovoltaic (PV) system normally consists of the following elements: PV energy generator (cell, module or array), PV power electronic systems (grid-tie inverter or maximum power point tracker (MPPT) or battery charge controller) and the load (energy consumer). The effciency in power transfer from the source to the load, largely depends on the impact of the environmental conditions on the PV module's performance and the electrical characteristics of the PV power electronic systems. Varying environmental conditions causes the non-linear output characteristics of the PV modules to change. In addition, the PV power electronics systems must be well suited to adapt to the change of the PV module's output characteristics in order to ensure power transfer at highest effciency. Different control strategies have been developed that controls the electrical characteristics of these systems to ensure maximum available power is delivered to the load. The manufactures and laboratories dedicated to the design and development of the PV power electronic systems, are faced with a responsibility of evaluating, optimising and certifying these systems according to specific performance standards. The conventional approach used to evaluate these systems involves having to conduct outdoor field experiments. The processes in field experiments involve having to connect actual PV modules to these systems. Moreover, the performance evaluation process is based on the power yield of the systems under the present environmental conditions. However, the processes are limited to the present environmental conditions albeit thorough evaluations under many different operating conditions are necessary. Therefore the conventional approach is largely dependent on environmental conditions. Furthermore, the approach is costly, time consuming and requires a lot of resources. In this thesis, a more appropriate and flexible approach is proposed. A system called the Solar Array Emulator (SAE) is designed and developed that is responsible for the performance evaluation of the PV power electronic systems. The SAE is a controllable indoor test facility that emulates the static and dynamic non-linear output characteristics of an actual PV module or array. A graphical user interface (GUI) is designed that allows the user to define the operating environmental conditions and the parameters of the actual module or array to be emulated. Based on the user-defined specifications, the SAE emulates the non linear output characteristics of an actual module. In addition, the SAE facilitates the evaluation of the PV power electronic systems' performance in steady-state and dynamic-state under different load and environmental conditions. The SAE has the advantage of being user friendly, flexible, compact and ensures thorough evaluation processes. The practical experiments conducted indicate that the proposed SAE system is able to successful emulate the dynamic and static characteristics of an PV module or array under different environment conditions. The experimental performance evaluations of two PV power electronics systems namely the grid-tie inverter and the maximum power point tracker are conducted using SAE. The experimental results obtained verifies the suitability of the proposed SAE to facilitate the performance evaluation of PV power electronic systems.
AFRIKAANSE OPSOMMING: 'n Tipiese foto-voltaïese stelsel bestaan gewoonlik uit die volgende elemente: foto-voltaïese energie kragopwekker (sel, module of skikking), foto-voltaïese drywingselektronika stelsels (netwerk gekoppelde omsetter of maksimum kragpunt volger of battery beheerder) en die las (energie verbruiker). Die doeltreffendheid van die stelsel hang grootliks vanaf die impak van die omgewings kondisies op die foto-voltaïese module en die elektriese eienskappe van die foto-voltaïese drywingselektronika stelsels. Wisselende omgewingstoestande veroorsaak dat die nie-lineêre uittree kenmerke van die PV modules verander. Daarbenewens moet die foto-voltaïese drywingselektronika stelsels geskik wees om aan te pas by die verandering van die uittree kenmerke van die foto-voltaïese module, om drywingsoordrag by hoogste doeltreffendheid te verseker. Verskillende beheer strategieë is al ontwikkel wat die elektriese eienskappe van hierdie stelsels beheer om te verseker maksimum beskikbare krag is aan die las gelewer. Die vervaardig en laboratoriums opgedra aan die ontwerp en ontwikkeling van die foto-voltaïese drywingselektronika stelsels is te make met 'n verantwoordelikheid van die evaluering, die optimalisering en sertifiseer hierdie stelsels volgens spesifieke prestasiestandaarde. Die konvensionele benadering wat gebruik word om hierdie stelsels te evalueer behels om buite in die veld eksperimente uit te voer. Die prosesse in veldeksperimente behels dat die werklike foto-voltaïese modules aan sluit op hierdie stelsels. Daarbenewens is die prestasie-evaluering proses wat gebaseer is op die krag opbrengs van die stelsels onder die huidige omgewingstoestande. Tog is die prosesse beperk tot die huidige omgewingstoestande, hoewel deeglike evaluering onder baie verskillende bedryfstoestande nodig is. Daarom is die konvensionele benadering grootliks afhanklik van omgewingstoestande. Verder is die benadering tydrowend en vereis baie hulpbronne en is duur. In hierdie tesis, is 'n meer gepaste en buigsame benadering voorgestel. 'n Stelsel genoem "Solar Array Emulator"(SAE) is ontwerp en ontwikkel, wat verantwoordelik is vir die prestasie-evaluering van die PV drywingselektronika stelsel. Die SAE is 'n beheerbare binnemuurs toetsfasiliteit wat die statiese en dinamiese nie-lineêre uittree kenmerke van 'n werklike PV module of skikking naboots. 'n Grafiese gebruikerskoppelvlak is ontwerp wat die gebruiker toelaat om die bedryf omgewingstoestande en die parameters van die werklike module of skikking wat nagevolg word, te definieer. Gebaseer op die gebruiker-gedefinieerde spesifikasies, die SAE naboots die nie-lineêre uittree kenmerke van 'n werklike module. Daarbenewens vergemaklik die SAE die evaluering van die prestasie van die foto-voltaïese drywingslektronieka stelsel in gestadige en dinamiese toestand onder verskillende las en omgewingstoestande. Die SAE het die voordeel dat dit gebruikersvriendelik, buigsame, kompak en verseker deeglike evaluering prosesse. Die praktiese eksperimente dui daarop dat die voorgestelde SAE stelsel in staat is om suksesvol die dinamiese en statiese eienskappe van 'n PV module of skikking onder verskillende omgewing voorwaardes te naboots. Die eksperimentele prestasie evaluerings van twee PV drywingselektronika stelsels, naamlik die netwerk gekoppelde omsetter en die maksimum kragpunt volger, is uitgevoer met behulp van SAE. Die eksperimentele resultate bevestig die geskiktheid van die voorgestelde SAE om die prestasie-evaluering van PV krag elektroniese stelsels te fasiliteer.
Description
Thesis (MScEng)--Stellenbosch University, 2016.
Keywords
Solar cell arrays, Solar batteries, Power electronics -- Equipment and supplies, UCTD, Electronic systems
Citation