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The increasing share of renewables in the energy mix, combined with a lack of storage facilities and a strong need of security in electricity supply, brings the need to keep back-up power plants based on fossil fuel in the field of electrical power generation. Due to high operational flexibility and high efficiency, Combined Cycle Gas Turbines (CCGTs) are great candidates to fulfill this role. However, these large combustion power plants need to switch to low-carbon emissions to reach the environmental objectives of carbon neutrality. To this end, Amine based carbon capture is the most promising and well-proven Post-Combustion Capture (PCC) technology to retrofit large combustion power plants. Nevertheless, this process is known to lead to significant amounts of thermal and electrical power consumptions, resulting in a significant energy penalty for the CCGT. To make the PCC economically competitive when integrated in gas-fired power plants, this energy penalty needs to be considerably reduced. Hence, four advanced configurations focusing on the regeneration process have been investigated to increase its energy efficiency: Lean Vapor Recompression (LVR), LVR combined with Overhead Gas Recompression (OGR), LVR combined with Rich Solvent Preheating (RSP) and Rich Vapor Recompression (RVR) combined with Cold Solvent Split (CSS). A base model was first established in Aspen Plus and validated against experimental data of a pilot scale facility. This PCC model was then scaled-up to a 770 MWe CCGT integrated with 35% Exhaust Gas Recirculation (EGR). Furthermore, key operating parameters of the proposed advanced configurations have been optimized enabling a fair comparison of their performance. LVR combined with RSP, using the reboiler condensate, turned out to be the most efficient advanced configuration for gas-fired power plants. This configuration enables to reduce the impact of the PCC unit on the CCGT net power down to 1.199 MJe/kgCO2 which represents a gain of 7.3 % compared to the conventional PCC process. Moreover, in gas-fired power plants, LVR has proven to be more efficient than the combination of RVR and CSS, unlike in coal-fired power plants. The next step will be to study the behaviour of LVR under part-load operations.

In the coming carbon-neutral era, industrial gas turbines (GT) will continue to play an important role as energy conversion equipment with high thermal efficiency and as stabilizers of the electric power grid. Because of the transition to a clean fuel, such as hydrogen or ammonia, the main modifications will lie with the combustor. It can be expected that small and medium-sized gas turbines will burn fewer inferior fuels, and the scope of cogeneration activities they are used for will be expanded. Industrial gas turbine cycles including CCGT appropriate for the carbon-neutral era are surveyed from the viewpoint of thermodynamics. The use of clean fuels and carbon capture and storage (CCS) will inevitably increase the unit cost of power generation. Therefore, the first objective is to present thermodynamic cycles that fulfil these requirements, as well as their verification tests. One conclusion is that it is necessary to realize the oxy-fuel cycle as a method to utilize carbon-heavy fuels and biomass and not generate NOx from hydrogen combustion at high temperatures. The second objective of the authors is to show the required morphology of the cooling structures in airfoils, which enable industrial gas turbines with a higher efficiency. In order to achieve this, a survey of the historical development of the existing cooling methods is presented first. CastCool® and wafer and diffusion bonding blades are discussed as turbine cooling technologies applicable to future GTs. Based on these, new designs already under development are shown. Most of the impetus comes from the development of aviation airfoils, which can be more readily applied to industrial gas turbines because the operation will become more similar. Double-wall cooling (DWC) blades can be considered for these future industrial gas turbines. It will be possible in the near future to fabricate the DWC structures desired by turbine cooling designers using additive manufacturing (AM). Another conclusion is that additively manufactured DWC is the best cooling technique for these future gas turbines. However, at present, research in this field and the data generated are scattered, and it is not yet possible for heat transfer designers to fabricate cooling structures with the desired accuracy. [ABSTRACT FROM AUTHOR]

Currently, the absence of a carbon footprint of wind and solar power plants is mistakenly viewed as an axiom. The impact of wind power plants and solar power plants on the growth of greenhouse gas emissions as a result of decreasing fuel efficiency of thermal power plants is not taken into account. The article aims to assess carbon dioxide emissions attributed to the generation of electric energy by CCGT, GTU, CHPP, WPP, SPP, HPP without regulated runoff, and HPP with regulated runoff. Wind and solar power plants have the greatest impact on the growth of greenhouse gas emissions in the energy system. Specific carbon dioxide emissions from wind and solar power plants exceed those from TPP for both natural gas and coal. Automatic issuance of green certificates for WPP, SPP, and HPP with regulated runoff, without analyzing and taking into account their contribution to the growth of carbon dioxide emissions in the UES of Russia, contradicts the climate goals of the Russian Federation. [ABSTRACT FROM AUTHOR]

THE PURPOSE. To consider the actual problem of determining the optimum value of the connected heat load to the cogeneration combined cycle gas turbine (CCGT) of the heat generation profile. METHHODS. Simulation modeling of operation modes using the "United Cycle" software is applied as a research method of the considered power unit operation. We studied several regimes of heat supply from the considered CCGTs during the heating period with the determination of integral annual indicators, as well as the relative fuel savings compared to the separate generation and the increase in the specific integral economic effect for different values of the cogeneration coefficient.RESULTS. We found that the optimal cogeneration coefficient for the object of study is 0.49. However, the value of the optimal cogeneration coefficient, determined by the condition of maximizing the specific integral economic effect for the object of research, is also 0.49. CONCLUSION. Determining the optimal unit commitment, which influences not only the initial investment, but also the expected operating (fuel) costs, is a pressing issue in power plant design. We present a basis for the possibility of using the indicator of relative fuel economy compared to separate generation as an optimization criterion. This parameter is widely used for optimization of combined heat and power units under conditions of planned economy. Under current economic conditions, it is possible to obtain a direct link between the incremental net discounted income from combined production and the relative fuel savings. This method can be used to analyze and optimize the mix of CCGT equipment regardless of geographical area, type of power system, energy resources cost, market conditions, as well as the characteristics of the used equipment.

Whilst various new technologies for power generation are continuously being evaluated, the owners of almost-new facilities, such as combined-cycle gas turbine (CCGT) plants, remain motivated to adapt these to new circumstances and avoid the balance-sheet financial impairments of underutilization. Not only are the owners reluctant to decommission the legacy CCGT assets, but system operators value the inertia and flexibilities they contribute to a system becoming predominated with renewable generation. This analysis therefore focuses on the reinvestment cases for adapting CCGT to hydrogen (H2), synthetic natural gas (SNG) and/or retrofitted carbon capture and utilization systems (CCUS). Although H2, either by itself or as part of SNG, has been evaluated attractively for longer-term electricity storage, the business case for how it can be part of a hybrid legacy CCGT system has not been analyzed in a market context. This work compares the power to synthetic natural gas to power (PSNGP) adaptation with the simpler and less expensive power to hydrogen to power (P2HP) adaptation. Both the P2HP and PSNGP configurations are effective in terms of decarbonizations. The best results of the feasibility analysis for a UK application with low CCGT load factors (around 31%) were obtained for 100% H2 (P2HP) in the lower range of wholesale electricity prices (less than 178 GBP/MWh), but in the higher range of prices, it would be preferable to use the PSNGP configuration with a low proportion of SNG (25%). If the CCGT load factor increased to 55% (the medium scenario), the breakeven profitability point between P2HP and PSNGP decreased to a market price of 145 GBP/MWh. Alternatively, with the higher load factors (above 77%), satisfactory results were obtained for PSNGP using 50% SNG if with market prices above 185 GBP/MWh. [ABSTRACT FROM AUTHOR]

Shrink and swell is a phenomenon that causes transient variability in water level once boiler load variation occurs. The leading cause of the swell effect is the steam demand changes and the actual arrangement of steam generating tubes in the boiler. Steam bubbles beneath HRSG drum water make the level control very difficult, particularly with significant disturbances in the input heat to HRSG. Plant shutdown may occur in some situations, and combined cycle plant efficiency is diminished. The recently applied control methods in industry are single-element and three-element control with PID controllers, but these methods are not well suited for substantial load changes. The main aim of this paper is to investigate the shrink and swell phenomenon inside HRSG power plants. In addition to the existing PID loops, two different standalone controllers, namely, the FOPID controller and fuzzy controller, are implemented with the HRSG model. Besides, Artificial Bee Colony (ABC) algorithm is used to tune FOPID efficiently. Based on overshoot, rise time, ISE, IAE, ITAE as performance measures, the comparison has been held between the three controllers. Simulations show that how the ABC optimization algorithm is efficient with PID, FOPID. It turns out that the proposed method is capable of improving system responses compared to the conventional optimal controller. • Discussing the shrink/swell phenomenon of drum level. • Discover how optimization algorithms can enhance PID controller response — By tuning it with the ABC algorithm. • Presenting two new recent three-element controllers using FOPID and fuzzy logic. • The application of ABC optimization algorithm to set the Membership function (MF) parameter of Fuzzy Logic. • Conducting comparative analysis between PID, FOPID and the Fuzzy logic controllers. [ABSTRACT FROM AUTHOR]

Nowadays, improving the efficiency of power plants by utilizing secondary energy resources is gaining more attention in the energy sector. In this paper, the combined cycle gas turbine (CCGT-420T) was considered, where exhaust heat from the main and auxiliary equipment is utilized, and sent to a water supply system through a closed-circuit heat exchanger, as a result, the heat transferred ( Q 6.4 MW) is rejected into the environment through a cooling tower. Moreover, an effective modelling method for utilizing heat in a closed cycle, using a steam compressing heat pump unit (HPU) is proposed. In addition, a calculation of the effectiveness of utilizing secondary energy resources depending on the number of HPU stages. In addition, the calculation of the effectiveness of the use of secondary energy resources depending on the number of stages of HPU was carried out. Several options of the model were discussed in this work, such as, two-, three-, and four-stage HPU and the coefficient of performance was calculated. Moreover, the work of these compressors for each option of the model was discussed in this work. Finally, the economic benefits of using of a multi-stage HPU instead of a traditional one-stage HPU during the annual operation of the CCGT-420T was discussed.

The structure of the operational costs of gas fired units (GFU) in real power systems is much more complex than what standard unit-commitment (UC) models consider in the state-of-the-art formulations. On the one hand, when a generation company owning several GFUs procures its gas -either totally or partially- at the gas spot market, the final fuel price will depend on the total gas purchases. This fact couples the operation of all the GFUs as it is impossible to build individual cost functions for each generator. On the other hand, as any other gas consumer, the generation company has to pay the gas Third Party Access (TPA) tariffs. The generation company must contract in advance the monthly TPA capacity for each gas exit point and depending on such decision, the final variable cost of the GFUs will be different. This paper states the importance of modeling properly both issues and presents a novel mathematical formulation that can be embedded in a self-UC model. The presented example case highlights the benefits of the proposed formulation. [ABSTRACT FROM AUTHOR]

The design and operating conditions of the low-pressure circut of Ep-258/310/35-15.0/3.14/0.44- 540/535/263 (P-132) heat-recovery steam generator (HRSG) as part of 795 MW CCGT were studied to reduce the wear of its tubes. Reliable and effective operating conditions of the natural-circulation loop are presented. The design of the low-pressure loop of P-132 is described. Modifications of the operating conditions to reduce the velocity of steam-water mixture in the natural-circulation loop, which, in turn, reduces the flow-accelerated corrosion, are described. In particular, the effect of changes in the drum pressure at constant and variable feedwater temperature on the velocity of the steam-water mixture is described. Methods and designs for eliminating gas shunts to equalize the heat absorption by the evaporator tubes in the HRSG are proposed. Several modifications of the HRSG design intended to reduce flow-accelerated corrosion are considered: a new evaporator design with outlet bends replaced with straight tubes; a new design of the riser system with more independent movement of the mixture from the evaporator; a different longitudinal spacing of evaporator tubes. The combined effect of modifications to the design and operating conditions on the reliability of the low-pressure loop is studied. It is concluded that the optimal solutions to reduce flow-accelerated corrosion are to increase the pressure in the low-pressure drum, to redesign the outlet section of the low-pressure evaporator and the low-pressure riser system, and to install anti-shunt partitions in the heating surfaces. These measures will allow steel 20 to be used to manufacture evaporation and riser tubes of the low-pressure loop due to the reduction of the velocity of steam-water mixture. [ABSTRACT FROM AUTHOR]

The paper analyses the possibilities to form a coalition of several heat energy providers in order to participate in the district heating market considering the open electricity market. Cooperation would allow the participants to better dispatch the existing energy sources and would ensure higher total profit for the participants. The objective function for such a cooperation is provided. To optimise the operation of the coalition, mixed integer linear programming is used, considering constraints of different heating energy market participants and the need to fulfil heating energy balance. If any additional profit is made, it is shared between coalition participants according to the Shapley value, which grants interest for market participants to form the coalition. Case study based on historical hourly data is provided and numerical results are presented in the paper. [ABSTRACT FROM AUTHOR]

The EU's "Green Deal" plans a carbonfree energy mix, neglecting nuclear energy, despite high social costs. Photovoltaic and wind power plants lack proper solutions for storing the excessive electricity. Their EROI is still lower compared to that of conventional sources. A complementary pair of combined cycle gas turbines (CCGT) and photovoltaics is a good solution for regular electricity supplies for households at affordable prices. Such a model is based on consumption data in Ruse (Bulgaria), delivered by Nicola Mihaylov et al. It also includes data, delivered by RIS Elektro OOD - a solar park operator. Matching consumption fluctuations with production fluctuations gives the following: A 1 MW CCGT that supplies up to 1,600-1700 households is combined with a 250 kW photovoltaic park. The calculations show that because of the park the CCGT should operate with lower EROI and "green surcharge" in the consumers' price. The optimal solution for energy deliveries requires a better balance between political, technical and economic factors. [ABSTRACT FROM AUTHOR]

Whilst various new technologies for power generation are continuously being evaluated, the owners of almost-new facilities, such as combined-cycle gas turbine (CCGT) plants, remain motivated to adapt these to new circumstances and avoid the balance-sheet financial impairments of underutilization. Not only are the owners reluctant to decommission the legacy CCGT assets, but system operators value the inertia and flexibilities they contribute to a system becoming predominated with renewable generation. This analysis therefore focuses on the reinvestment cases for adapting CCGT to hydrogen (H2), synthetic natural gas (SNG) and/or retrofitted carbon capture and utilization systems (CCUS). Although H2, either by itself or as part of SNG, has been evaluated attractively for longer-term electricity storage, the business case for how it can be part of a hybrid legacy CCGT system has not been analyzed in a market context. This work compares the power to synthetic natural gas to power (PSNGP) adaptation with the simpler and less expensive power to hydrogen to power (P2HP) adaptation. Both the P2HP and PSNGP configurations are effective in terms of decarbonizations. The best results of the feasibility analysis for a UK application with low CCGT load factors (around 31%) were obtained for 100% H2 (P2HP) in the lower range of wholesale electricity prices (less than 178 GBP/MWh), but in the higher range of prices, it would be preferable to use the PSNGP configuration with a low proportion of SNG (25%). If the CCGT load factor increased to 55% (the medium scenario), the breakeven profitability point between P2HP and PSNGP decreased to a market price of 145 GBP/MWh. Alternatively, with the higher load factors (above 77%), satisfactory results were obtained for PSNGP using 50% SNG if with market prices above 185 GBP/MWh.

This research provides new techno-economic insights into integrating flexible combined-cycle gas turbines with post-combustion carbon capture and storage (CCGT-CCS) for low-carbon power systems. This study developed a versatile unit-commitment optimisation model of CCGT-CCS. This research highlights the model's adaptability, accommodating diverse techno-economic configurations, feed gases (e.g., biomethane or fossil natural gas), carbon capture rates, and policy instruments. This generalisation empowers seamless application in various policy and market contexts, making the model a potent tool for researchers and policymakers. While the case study focuses on the UK, the findings are relevant for most low-carbon power systems with variable renewable supplies. Analysing the UK's net-zero scenarios from 2030 to 2050, the economic viability of flexible CCGT-CCS was highlighted. Intertemporal flexibility proves highly valuable with greater electricity price volatility, with a total ROI range of 81–246 %, surpassing the CCGT-CCS plant's ROI (7–64 %). A flexible solvent storage solution should be seen in the context of the overall system 'flexibility' requirements of a low-carbon power system. On a cost basis, solvent storage represents just a fraction of the capital costs of more "mainstream" energy storage technologies, such as lithium-ion batteries or hydro-pumped storage, while CCGT-CCS offers firm power. Overall, while seen as a rather technical solution, if abated fossil fuel generation is to be part of a future low-carbon power system, having this flexibility adds economic benefits not just to operators but also improves overall system security and complements high shares of variable renewables on the grid. [Display omitted] • Solvent storage in CCS can maximize profits from fluctuating low-carbon electricity markets. • Total return on investment from solvent storage greatly exceeds that of abated CCGT alone. • Solvent storage capital cost is a fraction of many "mainstream" energy storage technologies while providing firm power. • Flexible CCS with solvent storage boosts investor returns, system security, and aids renewable integration. [ABSTRACT FROM AUTHOR]

Abstract The growing share of intermittent renewable energy sources in electricity production allows for a significant reduction of the emissions of CO 2 and other pollutants from conventional, thermal power plants. As a side effect, it also leads to a noticeable increase of the number of start-ups and fast load transients encountered by those power plants used as back-up units. During such transient phases, the performances of those units in terms of pollutant emissions and thermal efficiency are however degraded, which results in a possible reduction of the environmental benefits of renewables that was not yet quantified. In this study, ten years of process data from a representative, large scale gas-fired combined cycle plant that underwent such a transition are analysed to assess the impact of frequent start-ups and load cycling on its average specific CO 2 and NO x emissions (per produced MWh e). While start-up and fast transient phases historically contributed to less than 5 % of the produced power, this share now reaches 5 − 20 %. As a consequence of the increased occurrence of such transients, the average specific NO x emissions increase by 30 to 80 % , from 140 up to 250 g/MWh e , and the average specific CO 2 emissions, less impacted, increase by 2 to 4 % , from 335 kg/MWh e up to 350 kg/MWh e. The impact of these findings on the expected reduction of CO 2 and NO x emissions attributable to the deployment of renewables is assessed. NO x emissions reduction is significantly lower than expected, due to the increased transient operation of conventional units. For shares of renewable sources lower than 30 % , the additional NO x emissions caused by peak demand operation of the thermal units compensate the emissions saved by decreasing their number of operating hours, resulting in a status quo in terms of global NO x emissions for the most optimistic scenario in terms of LCA emissions from renewable sources. For other scenarios, the global NO x emissions even increase for shares of renewables lower than 30 % , up to 110 % of the initial value (no renewables). As CO 2 emissions are much less sensitive to transient phases, the expected CO 2 emissions reduction is marginally affected by peak demand operation. Means of reducing both the occurrence of transient phases (at the level of the grid), and the related NO x emission peaks (at the level of the power plants) should be investigated, for a better integration of renewable sources and existing thermal assets. Highlights • The growth of renewables increases the number of transient phases in CCGT plants. • Their impact on specific CO 2 and NO x emissions was quantified on real data. • CO 2 emission reduction due to growth of renewables is only marginally affected. • The NO x emission reduction is significantly lower than expected due to transience. • The renewables share needs to exceed at least 30% for overall NO x reduction. [ABSTRACT FROM AUTHOR]

This article covers the use of supplementary firing in a gas-combined cycle power plant when high flexibility is required depending on the penetration of variable renewable energies and under different gas turbine loads. Process models were simulated under different operating conditions with the software EBSILON®Professional. Five main conditions were studied for the designed combined cycle: gas turbine part-load without supplementary firing, gas turbine full load with supplementary firing, the use of supplementary firing to overcome the effect of changing ambient conditions, part-load gas turbine performance with supplementary firing technology and the use of supplementary firing in case of gas turbine shutdown. [ABSTRACT FROM AUTHOR]

The value of dispatchable, low carbon thermal power plants as a complement to intermittent renewable energy sources is becoming increasingly recognised. In this study, we evaluate the performance of post-combustion CO 2 capture using monoethanolamine (MEA) retrofitted to a 600 MW CCGT, with and without exhaust gas recycle (EGR). Our results suggest that the EGR ratio plays a primary role in the regeneration energy penalty of the process. We contrast a gas-CCS process with its coal counterpart and show that whilst CCGTs have a greater energy penalty per tonne of CO 2 captured than coal ( i.e. , G J t C O 2 G a s > G J t C O 2 C o a l ), owing to the high thermal efficiencies of CCGTs relative to coal-fired power plants, the energy penalty per MWh of low carbon energy generated is lower for gas than it is for coal ( i.e. , G J M W h G a s < G J M W h C o a l ), making CCGT-CCS an attractive choice for low carbon electricity generation. [ABSTRACT FROM AUTHOR]

Combined cycle gas turbine power plants (CCGTs) play a key role in modern electric power systems due to their operational flexibility and the firmness they provide to the networks where they operate. Due in part to this flexibility and firmness, the function of CCGTs has experienced a significant evolution with the advent of intermittent renewable energy sources such as wind: CCGTs are increasingly required to rapidly vary load levels in order to counterbalance the fluctuations of renewable energy sources and satisfy overall system demand. The purpose of this paper is to develop a methodology that can be used for assessing the optimal operational strategy of a CCGT when subjected to cycling requirements. This is achieved by introducing a unit commitment formulation that takes into account useful life expenditure costs due to fatigue damage accumulation associated to cycling. The case studies presented in this paper show that neglecting fatigue cycling costs when making operational decisions generates suboptimal cost and profit outcomes for CCGT operators. Furthermore, it is shown that profitability of CCGTs is compromised in systems with very significant penetration of intermittent renewable energy sources, due to the increase in cycling costs derived from continuous load-following operation. [ABSTRACT FROM AUTHOR]

The use of natural gas for power generation is becoming increasingly important in many regions in the world. Given that the combined cycle gas turbine (CCGT) power stations are lower in capital cost and carbon intensity than their coal-fired counterparts, natural gas fired power stations are considered a vital part of the transition to a low carbon economy. However, CCGTs are not themselves “low carbon” and in order to reach a carbon intensity of less than 50 kg CO 2 /MWh, it will be necessary to decarbonise them via CCS, with post-combustion CCS currently regarded as being a promising technology for this application. In this study, we present a detailed model of a 420 MW triple-pressure reheat CCGT and evaluate its technical and economic performance under full and part load conditions. We evaluate the technical performance of our CCGT model by comparison to an equivalent model implemented in Thermoflow THERMOFLEX and observe agreement of power output and efficiency to within 4.1% and the temperature profile within the HRSG within 2.9%. We further integrate the CCGT with a dynamic model of an amine based CCS process, and observe a reduction in the base plant efficiency from 51.84% at full-load and 50.23% at 60% load by 8.64% points at full-load and 7.93% points at 60% load. A core conclusion of this paper is that CCGT power plants equipped with post-combustion CCS technologies are well suited to dynamic operation, as might be required in an energy system characterised by high penetrations of intermittent renewable power generation. [ABSTRACT FROM AUTHOR]

The political rhetoric would have it that the dramatic decline in the use of coal in the U.S. since 2008 has been a result of ‘Obama’s war on coal’ – that is, the EPA’s Clean Air rules. But the data say otherwise. Rather, enabled by shale drilling, cheap natural gas is outcompeting coal markedly. An analysis that includes gas’s techno-economic pluses concludes the trend will continue. [ABSTRACT FROM AUTHOR]

Concentrating Solar Power (CSP) plants utilize thermal conversion of direct solar irradiation. A trough or tower configuration focuses solar radiation and heats up oil or molten salt that subsequently in high temperature heat exchangers generate steam for power generation. High temperature molten salt can be stored and the stored heat can thus increase the load factor and the usability for a CSP plant, e.g. to cover evening peak demand. In the HYSOL concept (HYbrid SOLar) such configuration is extended further to include a gas turbine fuelled by upgraded biogas or natural gas. The optimised integrated HYSOL concept, therefore, becomes a fully dispatchable (offering firm power) and fully renewable energy source (RES) based power supply alternative, offering CO 2 -free electricity in regions with sufficient solar resources. The economic feasibility of HYSOL configurations is addressed in this paper. The CO 2 free HYSOL alternative is discussed relative to conventional reference firm power generation technologies. In particular the HYSOL performance relative to new power plants based on natural gas (NG) such as open cycle or combined cycle gas turbines (OCGT or CCGT) are in focus. The feasibility of renewable based HYSOL power plant configurations attuned to specific electricity consumption patterns in selected regions with promising solar energy potentials are discussed [ABSTRACT FROM AUTHOR]

Gas turbines inherently depict unique frequency response characteristics compared with other conventional synchronous generation technologies as their active power output is not entirely determined by the governor response during frequency deviations of the power network. Thus, gas turbine dynamics significantly influence on system stability during frequency events in power networks. Power system and power plant operators require improved understanding of the gas turbine characteristics during various frequency events in order to mitigate adverse impact on power system. Therefore a comparative analysis has been performed between combined‐cycle gas turbines (CCGTs) and open‐cycle gas turbines (OCGTs) in order to characterise the dynamic behaviour considering different types of frequency events in power networks. Study has shown that CCGTs result in significant frequency variations in power networks in comparison with OCGTs because of the temperature control action performed by the fast acting inlet guide vanes at the combustor. In particular, they are susceptible to lean blowout during large frequency increase events such as short‐circuit faults in power networks. Furthermore, a case study was developed based on the New England‐39 bus system in order to illustrate the impact of gas turbine dynamics on network frequency during short‐circuit events in power networks. [ABSTRACT FROM AUTHOR]

This paper presents a thermo-economic optimization of a combined cycle power plant obtained via the Proper Orthogonal Decomposition-Radial Basis Functions (POD-RBF) procedure. POD, also known as "Karhunen-Loewe decomposition" or as "Method of Snapshots" is a powerful mathematical method for the low-order approximation of highly dimensional processes for which a set of initial data is known in the form of a discrete and finite set of experimental (or simulated) data: the procedure consists in constructing an approximated representation of a matricial operator that optimally "represents" the original data set on the basis of the eigenvalues and eigenvectors of the properly re-assembled data set. By combining POD and RBF it is possible to construct, by interpolation, a functional (parametric) approximation of such a representation. In this paper the set of starting data for the POD-RBF procedure has been obtained by the CAMEL-Pro™ process simulator. The proposed procedure does not require the generation of a complete simulated set of results at each iteration step of the optimization, because POD constructs a very accurate approximation to the function described by a relatively small number of initial simulations, and thus "new" points in design space can be extrapolated without recurring to additional and expensive process simulations. Thus, the often taxing computational effort needed to iteratively generate numerical process simulations of incrementally different configurations is substantially reduced by replacing much of it by easy-to-perform matrix operations. The object of the study was a fossil-fuelled, combined cycle powerplant of nameplate power Pel=160MW, for which a set of operational and costing data was available: different combinations of the relevant process parameters were considered and the corresponding process variables calculated for each simulation were collected. In our case the aim of the application of the procedure was to find the combination of process parameters which corresponds to the minimum the thermo-economic cost of the products. The results obtained by the application of this model have been validated by comparison with literature data obtained by the application of genetic algorithm optimization. [ABSTRACT FROM AUTHOR]

Abstract: This paper shows the experimental and numerical analysis of a biomass steam power plant from maximum power of 2.3 MW with a maximum pressure of 48bar and a turbine inlet temperature of about 430°C at the design point. The analysis has been conducted using experimental data, collected directly on the power plant, at the design point, and they have been afterwards used to validate a thermodynamic model. The analysis of the biomass power plant pointed out some critical issues that can be summarized in three points: low plant efficiency due to the small size, biomass supply range and continuous variation of the operating point. In order to solve this problem, different plant configurations were numerically evaluated. The first solution to these problems consists of a 100 kWe micro gas turbine (MGT) fueled by natural gas, whose exhaust gas were sent to the steam generator of the biomass power plant in order to evaluate the benefits on the power fluctuations and on global electric efficiency. A thermodynamic model of the MGT has been developed and validated with experimental data from technical literature, creating a CCGT (Combined Cycle Gas Turbine) system. The analysis of the results of this system showed improvement in terms of efficiency and operational stability. The second option was to fuel the previously validated method of MGT with four different alternative fuels and to evaluate the integration with the biomass plant for all of them. Furthermore, to emphasize the benefits of this integration, the power of the micro turbine has been increased assuming the use of more MGT at the same time. These analyses show an increase of the system efficiency, it could been also used the biomass, not suitable for direct combustion (high humidity), to produce biogas that fuels the MGT, reducing the range of biomass supply. [Copyright &y& Elsevier]

Highlights: [•] High fidelity modelling of NGCC power plant with CO2 capture and compression. [•] Thermodynamic analysis of the impact of EGR on the capture plant. [•] EGR is shown to increase mass transfer in capture plant absorber. [•] Rigorous analysis of the supplementary firing of a gas turbine exhaust gas. [•] Economic analysis via a bottom-up approach using material costs and wage rates. [Copyright &y& Elsevier]

Major blackouts of power systems in recent years show the importance of power system stability studies. One of the most discussed stability problems is island operation. Combined cycle power plants are one of the major supplies of Slovak power system nowadays. Their mainly purposes are power generation and household heating. Gas turbines are very well known for their fast response, so it is necessary to discuss their application in blackstart service and restoration process in island operation. One of the most important variables that has to be observed in the island operation is frequency, because power plants could operate safely only in region of 48 to 51.5 Hz. The aim of this paper is to provide a study of blackstart of combined cycle power plants in Slovak Power System and stability of an islanded power system. Simulation results are given. One of the most important results of this paper is to show the behaviour of combined cycle power plants on restoration process in island operation. [ABSTRACT FROM AUTHOR]

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Abstract: This paper presents experimentally measured data showing the impact of variable demand on a modern 800 MW CCGT plant. The results contrasting the performance of the plant when operating under optimum conditions with those measured when modulating the output to match dispatch instructions is presented and compared. These contrasts include the impact of step changes, continual modulation and both hot and cold starts of the plant. The results indicate the changes in fuel used per MWh, CO2 emitted per MWh and the NOx emissions under different operating modes. From the subsequent analysis significant increases were recorded in both fuel used and CO2 emitted when the plant departs from optimum operating conditions. When the plant is requested to cease generating due to over capacity on the system, major increases in the emissions of NOx, when required to restart generation together with large increases in the fuel used and CO2 emitted per MWh, can be observed. [Copyright &y& Elsevier]

Abstract: Significant changes to the generation mix on the British transmission system have occurred in the past 10 years, and this trend is expected to continue in the future with an increase in renewable generation. This change, in conjunction with market changes, has driven the need to establish suitable generator models for thermal plant used in dynamic response studies. These studies are presently used to quantify the dynamic requirement that secures the transmission system against large instantaneous losses of power. This paper provides an account of the experiences gained in modelling the performance of generators based in Great Britain. Established governor models to represent the behaviour of traditional coal and oil fired plant already exist and comments are made on their performance against system incidents. Models of combined cycle units using traditional open cycle gas turbine models have shown poor correspondence with monitored grid data in simulations. A gas and steam turbine governor model to represent combined cycle plant was developed, and is presented, with results from validation trials against recorded test data. Improvements in simulating grid frequency have been demonstrated using the developed models in a full network simulation of a recent generator loss event. [Copyright &y& Elsevier]

The high penetration of renewable energy sources makes the two-by-one combined cycle gas-turbine (2 × 1 CCGT) with high operational flexibility (OPFL) become the mainstream of deep peak-load units. However, the thermos-exchanger water level (TEWL) often exceeds the limit and causes unit trip during flexible operations. For this reason, this paper proposes a flexible operational TEWL control strategy. First, by modeling and analyzing the thermodynamics of the thermal-supply system of 2 × 1 CCGT unit, the exhaust steam pressure of intermediate pressure cylinder (IPEP) is chosen as an upstream controlled variable with mathematical-model derived setpoint to stabilize the TEWL; Secondly, considering the heat storage utilization of heating network, the heating-network circulating water flow is selected as the manipulated variable of IPEP control, then forming a pilot IPEP control loop cooperating with the existing TEWL control loop to stabilize the TEWL. Several control algorithms are designed and compared to determine the most effective one for the IPEP pilot-TEWL control. The results show that the maximal deviation of TEWL can be reduced to 7 mm and the OPFL indexes can be significantly improved, i.e. the average power ramp rate is 6.74 MW/min, and the power capacity is 69.55 MW from 158 MW steam turbine. • A control-oriented dynamic model of thermal-supply of 2 × 1 CCGT is presented. • A pilot control strategy is proposed to enhance the stability of the TEWL. • Several control algorithms are designed and compared on stabilizing TEWL. • The pilot control strategy can greatly improve the operational flexibility of CCGT. [ABSTRACT FROM AUTHOR]