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This work considers the value of flexible power provision from natural gas-fired combined cycle (NGCC) power plants operating post-combustion carbon dioxide (CO2) capture in low carbon electricity markets. Specifically, the work assesses the value of the flexibility gained by varying CO2 capture levels, thus the specific energy penalty of capture and the resultant power plant net electricity export. The potential value of this flexible operation is quantified under different electricity market scenarios, given the corresponding variations in electricity export and CO2 emissions. A quantified assessment of natural gas-fired power plant integrated with amine-based post-combustion capture and compression is attempted through the development of an Aspen Plus simulation. To enable evaluation of flexible operation, the simulation was developed with the facility to model off-design behaviour in the steam cycle, amine capture unit and CO2 compression train. The simulation is ultimately used to determine relationships between CO2 capture level and the total specific electricity output penalty (EOP) of capture for different plant configurations. Based on this relationship, a novel methodology for maximising net plant income by optimising the operating capture level is proposed and evaluated. This methodology provides an optimisation approach for power plant operators given electricity market stimuli, namely electricity prices, fuel prices, and carbon reduction incentives. The techno-economic implications of capture level optimisation are considered in three different low carbon electricity market case studies; 1) a CO2 price operating in parallel to wholesale electricity selling prices, 2) a proportional subsidy for low carbon electricity considered to be the fraction of plant electrical output equal to the capture level, and 3) a subsidy for low carbon electricity based upon a counterfactual for net plant CO2 emissions (similar to typical approaches for implementing an Emissions Performance Standard). The incentives for variable capture levels are assessed in each market study, with the value of optimum capture level operation quantified for both plant operators and to the wider electricity market. All market case studies indicate that variable capture is likely to increase plant revenue throughout the range of market prices considered. Different market approaches, however, lead to different valuation of flexible power provision and therefore different operating outcomes.

Thesis (MIng)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Fouling is readily acknowledged as one of the most critical problems limiting the wider application of membranes in liquid separation processes. A better understanding of fouling layer formation and its monitoring is needed in order to improve on existing cleaning techniques. Plant operation can be optimised if fouling can be monitored by noninvasion means either on the plant itself or on an attached monitoring device. The overall scope of this research was to develop a non-destructive, real-time, in situ visualisation technique or device for concentration polarisation and fouling layer monitoring. Ultrasonic-time-domain-reflectometry (UTDR) was employed as a visualisation technique to provide real-time characterisation of the fouling layer. A 24 cm-long rectangular flat sheet aluminium cell was designed and used as separation device for a desalination system. The experimental results obtained using this module confirmed that there are an excellent correspondence between the flux decline behaviour and the UTDR response from the membrane. The ultrasonic technique could effectively detect fouling layer initiation and growth on the membrane in real-time. In addition to the measurement of fouling, the ultrasonic technique was also successfully employed for monitoring membrane cleaning. Since no real-time permeation data is available during cleaning operations in industrial applications, a UTDR monitoring device may prove to be a very valuable technique in optimising cleaning strategies. The technique was further tested on an 8-inch diameter spiral wrap industrial module and good results were obtained. Stagnant zones, as well as flux flow behaviour inside the module could be determined. However, more research IS needed to fully understand the complex phenomena inside a spiral wrap module. Overall, the UTDR technique and its use in monitoring devices have a major impact in the membrane industry due to its extremely powerful capabilities. / AFRIKAANSE OPSOMMING: Membraan-bevuiling of -verstopping is die grootste struikelblok wat die algemene aanwending van membrane vir verskillende watersuiweringsprosesse negatief beinvloed. 'n Beter begrip van membraan-bevuiling, asook beter metingsmetodes daarvan is nodig om op bestaande skoonmaaktegnieke te verbeter. Die hoofdoel van hierdie studie was die ontwikkeling van 'n nie-destruktiewe-in-lyn visuele tegniek vir die meting van konsentrasie polarisasie en membraan-bevuiling. Deur gebruik te maak van ultrasoniese klank golwe, is 'n tegniek ontwikkel wat 'n direkte visuele aanduiding kon gee van die toestand van membraan-bevuiling binnein die module. 'n Reghoekige aluminium-module, 24 cm lank, is ontwerp en gebou waarbinne die membraan geplaas is vir die skeidingsproses. Resultate dui daarop dat daar 'n uitstekende verband bestaan tussen die afname in permeaatvloei en die ultrasoniese eggo vanaf die membraan. Die ultrasoniese tegniek kon die vorming van en toename in membraan-bevuiling doeltreffend karakteriseer. In teenstelling hiermee, is die tegniek ook suksesvol aangewend om die skoonmaak-proses van membrane te ondersoek. Met min of geen data beskikbaar vir die skoonmaak-proses van membrane in die industriële sektor, het die tegniek enorme potensiaal in die optimisering van bestaande skoonmaak-tegnieke. Die tegniek is verder aangewend op 'n industriële 8-duim deursnee spiraal-module en goeie resultate is verkry. Stagnante sones asook vloed-vloei-patrone binne-in die module kon suksesvol bepaal word. Baie navorsing is egter nog nodig om die ingewikkelde data wat gegenereer word tydens die ondersoek van 'n spiraal-module ten volle te verstaan. Die enorme potensiaal en moontlikhede van die ultrasoniese tegniek kan die begin wees van 'n revolusie in die membraan-industrie.

This thesis deals with operation of the Jasenie hydroelectric power plant, which supplies electricity to Železiarne Podbrezová Inc. This thesis describes actual operation, devices and equipment in all substations. The second chapter briefly describes company’s history and activities of the company. The next chapter mentions an overview of the sources of own electricity production. The fourth chapter in detail deals with actual situation of the hydroelectric power plant operation, describes devices and equipment in all substations. It also outlines what measures should be taken to increase the reliability of electricity supply. Next part deals with replacing insulators on the 22 kV line. Sixth chapter is focused on protection this line by multifunctional protection relay and data transfer from HC Jasenie to the building of power engineering. In the next step is designed a backup transformer with bus control for thermal and dynamic effects of the short-circuit current. The last chapter is focused on surge protection in HC Jasenie as well as in the area of Stary závod substation. The results and benefits of this work are summarized in the conclusion. The attachment contains schemes of substations and overall overview scheme, which are used for better understanding of this problem.

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The aim of the Thesis is theoretical clarification of the issues of photovoltaic power plants, their diagnostics, inspection and performance measurement, including negative impacts on their operation and subsequent application of theoretical knowledge during practical inspection and diagnostics of PV power plants. In its introductory part, the Thesis deals with design, manufacturing and development of PV cells and panels and describes other necessary elements and components, including their use in individual types of photovoltaic systems. Another part describes electric parameters of PV cells and panels, especially the parameters that can be found out by measurement of V-A characteristics and also the parameters affecting the shape of the V-A characteristics. The third part is focused on failures of photovoltaic systems, which include various defects of photovoltaic cells and panels, it also provides for adverse factors affecting operation of the entire system, associated not only with weather influences but also with the actual design of the photovoltaic system. The fourth part deals with possibilities of increasing the cost-effectiveness of electricity generation by PV power plants on the basis of practical experience of their operators. The subsequent part determines, on the basis of technical standards, procedures for PV power plant inspections, the procedures for measurement and diagnostics of PV power plants and also other prerequisites connected with inspections and measurements. This part includes also a description of requirements for measuring devices, most frequent measurement errors, adverse impacts affecting measurements and methods of assessment of the data measured. The last part of the Thesis is practical. At first it deals with verification of the impact of defects of PV modules on the shape of their V-A characteristics, then with execution of inspections and diagnostics of a particular PV power plant, evaluation of the data identified and measured, as well as with a proposal of optimisation measures to increase cost-efficiency of the operation of that particular PV power plant.