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To balance the intermittent renewable energy and cope with the increasing nuclear power installed capacity in China, it is necessary for nuclear power plants (NPPs) to operate with load-following mode for enhancing economic competitiveness. The modular high temperature gas-cooled reactor (MHTGR) is an appropriate candidate for load-following operation due to the advanced features such as robust fuel elements, online fueling and full-power-range temperature negative feedback. The MHTGR-based nuclear steam supply systems (NSSS) which produces superheated steam flow for electricity, is the core for any NPPs. The proper control of NSSS is the prerequisite for the safe, stable and efficient load-following operation. However, in current engineering practice, the set-point trajectories of neutron flux, primary coolant temperature, primary and secondary flowrates are just the curves by linking the referenced steady values from the thermal hydraulic design, which are further determined by the thermal power requirement. Thus, it is meaningful to investigate an optimization-oriented control method to improve the operation efficiency. Motivated by this, two dynamic matrix control (DMC) with cascade structure are presented to improve both thermal power and steam temperature of the MHTGR-based NSSS. The thermal power is optimized by the first DMC through adjusting the set-point of nuclear flux. The second DMC is then designed based on the integration of the NSSS, the proportional-integral-derivative (PID) and the first DMC to improve the steam temperature response by adjusting the feed-water flowrate. The control performance during wide range operation is shown and discussed with the simulation results of a large-scale MHTGR plant model.

To integrate more renewable energy into the power grid, thermal power plants have to accelerate the speed of power output and extend their operating ranges, and this can result in great challenges for their safe operations and even safety accidents. To this end, a gain scheduling design based on active disturbance rejection control (ADRC) is proposed for thermal power plants under full operating conditions. The urgency of the proposed control strategy is illustrated by analyzing the control difficulties of coordinated control systems. Then the scheduling parameter selection and the linear switching method for the proposed control strategy are analyzed. Moreover, the qualitative stability analysis based on the Kharitonov theorem and the quantitative calculation of stability regions are carried out to ensure the stability of the closed-loop system. Simulations of the power tracking under different load tracking rates and disturbance rejection under the coal quality variation are carried out. Simulation results show that the tracking and disturbance rejection performance in both power output and throttle pressure loops has been improved simultaneously compared with the regular ADRC and the traditional proportional-integral control strategies. Based on the verified superiority, the proposed gain scheduling design based on ADRC shows a promising potential in industrial applications.

Among the various heating technologies that can be applied to urban areas district heating is recognized to allow significant reduction in primary energy consumption, provided that the system is properly designed and operated. Thermo-fluid dynamic simulation tools can be of extreme importance in order to achieve this objective. This paper aims at presenting a thermo fluid dynamic model for the detailed simulation of large district heating network and showing how it can be usefully applied to examine options for the reduction of primary energy consumption. The model is tested using experimental data and then applied for analyzing transient operations of the Turin district heating network, which is the largest network in Italy and one of the largest in Europe. A comparison between simulations and experimental results shows that the model is able to predict the temperature in the nodes of the network with good accuracy. The thermal power required to each plant is also calculated with a good level of accuracy. The model can be used for the simulation of operational strategies, thus representing a versatile and important tool for the implementation of advanced management such as the installation of local storage units or the variation of user request schedules.

In order to reduce the power curtailment of renewable energy, it is essential to improve the dispatchability of thermal power generating unit, among which the dynamic characteristics of the cold end system under varying operating conditions are of significant and necessary. Taking the thermal power plants with indirect dry cooling systems as object, the unsteady models for the dynamic characteristics of cold end were established. The transient behavior under the changing natural crosswind or power load were obtained. Four cooling water adjusting strategies were proposed to compare the standard coal consumptions during operating condition varying. The results indicate that the back pressure and cooling water temperature can change slowly despite of the abruptly change of the natural wind speed and output power load. It takes the cold end longer time to reach another stable state when the natural crosswind speed changes to a bigger value or the output power load decreases in a slower rate. The difference of ambient temperature and natural crosswind speed hardly affects the dynamic behaviors of the cold end system. When the cooling water flow rate is adjusted in the proper way, at most 21.4% more standard coal could be saved during load decreasing processes.

The exploitation of renewable energy sources and the use of primary energy saving techniques have been recognized as key solutions to face climate changes. The consequent energy policies are pushing the transition from a centralized power generation system to a distributed polygeneration system able to meet simultaneous heating, cooling and electricity demand. However, small scale polygeneration plants do not ensure any primary energy and cost saving without a proper sizing and operation of the plant. Furthermore, a flexible configuration of the waste heat recovery system (WHRS) adopted for polygeneration purposes can be equally important. Therefore, starting from the experimental data concerning a 15 kW micro-CHP plant previously designed and prototyped, the paper addresses the performance assessment of a CHCP plant configuration based on the same basic engine-electric generator system through the 1D thermo-fluid dynamic characterization of an alternative double water circuit WHRS. This configuration, delivering thermal power at different temperature level, could be useful to meet thermal and cooling demand from different user or when seasonal energy demand occurs. This paper also provides an effective approach for the design of WHRS which are capable to ensure a reasonable matching between the temperature level required by the user and that provided by the plant. In this way, being the energy saving dependent on the thermal power recovered and actually exploited, and so on the temperature level which characterizes the user's heat demand, primary energy savings are more easily achievable even when small scale polygeneration applications are considered. Results shows the possibility of supplying an absorption chiller and obtaining a coolling capacity of about 10.5 kW from the resulting CHCP plant configuration.

To go hand in hand with the development of the country and face the rapidly increasing energy demand, Morocco began developing a green plan in order to produce 2000 MW of renewable energy on the horizon of 2020. Solar conversion is believed to play a pivotal role in the Moroccan energy transition. The principle objective of this work is to comprehensively overview the Moroccan parabolic trough solar thermal power plant Noor 1 as one of the leading solar plants in Africa and Middle-East. The main motivations behind the site selection as well as a detailed technical description of the plant are provided. For the first time, existing similar parabolic trough solar thermal power plants worldwide are reviewed and compared. It was concluded that the specific energy generation of Noor 1 is well ranked among the compared plants (superior to 61.5% of other plants).

Improving denitrification efficiency of supercritical unit for peak load regulation by changing feed water temperature has become a focus of thermal power engineering under wide load. However, the effect mechanism of feed water temperature on the performance of supercritical unit is indistinct absolutely at the intermediate point temperature (IPT)-setting mode, which obstructs the performance optimization and the excavation of energy saving of supercritical unit with a change of feed water temperature aims at improving denitrification efficiency of supercritical unit. For the purpose, a closed cycle theory in which thermal power unit operating parameters interact and form a closed influence mechanism was defined and proposed, with such a core ideology, the performance analysis and assessment models under IPT-setting mode is constructed on the differential theory, energy balance and thermodynamics method, and the accuracy of established model is verified. These developed models are applied to assess the operational performance and to identify energy saving potential of supercritical unit for peak load regulation. Subsequently, a typical 660 MW ultra-supercritical coal fired power plant is selected as a reference case. Not only a quantitative analysis of effect of increasing feed water temperature adding HP heaters on supercritical unit performance is performed, but the effect of reducing feed water temperature stopping HP heaters on supercritical unit performance is implemented as well at the IPT-setting mode. Finally, the influence mechanism of feed water temperature on boiler thermal efficiency, steam turbine thermal consumption rate, standard coal consumption rate, power generation, denitrification efficiency, NOx production, steam temperature and other operating parameters of supercritical unit is absolutely revealed on IPT-setting mode. The investigation results show that the sensitivity of feed water temperature to supercritical unit performance varies greatly in different range of feed water temperature, especially when the feed water temperature is heated to the near the pseudo critical temperature, a dramatic change would take place in operation parameters of supercritical unit. Such a viewpoint is presented rigorously that increasing feed water temperature does not always achieve energy saving for supercritical units, also contrary to the existing viewpoint.

Optimal operation of district heating (DH) systems usually relies on the forecast of thermal demand profiles of the connected buildings. Depending on the purpose of the analysis, thermal request can be required at various levels, from building level to thermal plant level. In the case of demand response for example, thermal request is necessary at a building level to evaluate its applicability and at a plant level to determine the effects. Thermal request profiles are quite different, depending on the observation point. Total requests are not just the summation of the downstream requests, mainly because of the thermal transients. The heat losses also contributes to modify the curves, although generally in a smaller way. In this work, a multi-level thermal request prediction is proposed. This approach has the aim of evaluating the thermal request in the various sections of DH network with reduced computational resources. This includes a compact model for the prediction of building demand and a network model in order to compose together the requests at the various levels. The application to a portion of the Turin district heating network is proposed. This shows that the network dynamics significantly affects the evolution, especially at peak load.

Photovoltaic/thermal (PV/T) technologies are used to comprehensively utilize photovoltaic and solar thermal, among which concentrating PV/T technology can enhance the performance of a PV/T system. To analyze the performance of a LCPV/T system with a geometric concentration ratio of 4, the LCPV/T system and a conventional flat-plate PV/T system were fabricated and experimentally studied under a constant flow rate condition. The results show that the electrical power and thermal power of the LCPV/T system were 3 and 1.9–2 times more than those of the flat-plate system. The comparative experimental study indicates that the electrical performance of LCPV/T system is significantly greater than the flat-plate system, and the thermal performance of LCPV/T system slightly improved and should be optimized because of the heat transfer factor.

In today's China, the reverse distribution of electricity resources and electricity demand makes large-scale and long-distance transmission of electricity inevitable, resulting in the problem of electricity allocation optimization. To address this problem in the region covered by the China Southern Grid (CSG), the paper establishes an optimized model for electricity generation and interprovincial trading strategies in southern China. Based on data from 2015, this paper simultaneously optimizes electricity generation and interprovincial trading strategies in each of the five provinces. The result shows that interprovincial trading in the CSG-served area can yield significant energy, economic, environmental and interconnection benefits. It can reduce the power supply cost and environmental pressure in Guangdong province, help make Yunnan province a hydropower base in China and a thermal power base in southern China, facilitate the completion of the “West-to-East Power Transmission” project, and partly resolve the issues raised in each province's 13th Five-Year Plan as well as the problem of optimizing electricity allocation in the region covered by the CSG.

Two methods for monitoring the thermal stresses in pressure components of thermal power plants are presented. In the first method, the transient temperature distribution in the pressure component is determined by measuring the transient wall temperature at several points located on the outer insulated surface of the component. The transient temperature distribution in the pressure component, including the temperature of the inner surface is determined from the solution of the inverse heat conduction problem (IHCP). In the first method, there is no need to know the temperature of the fluid and the heat transfer coefficient. In the second method, thermal stresses in a pressure component with a complicated shape are computed using the finite element method (FEM) based on experimentally estimated fluid temperature and known heat transfer coefficient. A new thermometer with good dynamic properties can be used for providing a much more accurate temperature of the flowing fluid in comparison with standard thermometers. A numerical-experimental method of determination of the transient heat transfer coefficient based on the solution of the 3D-inverse heat conduction problem was proposed. The heat transfer coefficient on the internal surface of a pressure element can be estimated based on an experimentally determined local transient temperature distribution on the external surface of the element or on the basis of wall temperature measurement at six points located near the internal surface if fluid temperature changes are fast. Examples of determining thermal and pressure stresses in the thick-walled horizontal steam header with the use of real measurement data are presented.

High thermal loads of the thick-walled components arise during the start-up and shutdown in the thermal power units, both classical and nuclear. The thermal stresses should be determined on-line during start-up of the power unit, to avoid reducing the lifetime of the so-called critical pressure components. It is necessary to know the time variations in fluid temperature, and heat transfer coefficient on the internal surface of the pressure components to determine the transient distribution of temperature and thermal stresses in the critical components of boilers. The thermal stress can only be calculated correctly if the temperature of the flowing fluid is accurately measured. Unfortunately, massive industrial thermometers used in power units are not able to measure the transient temperature of the fluid with sufficient accuracy due to their high thermal inertia. The goal of the paper is to present the use of the new measurement technique to determine the unsteady temperature of the superheated steam. The temperature of superheated steam was measured after the second stage of superheater using the proposed measuring technique and conventional industrial thermometers that are used today. The tests carried out showed very clearly the advantage of the proposed method over conventional thermometers.

This paper presents a new methodology that allows to define a 100% renewable smart energy system in a sustainable manner. The authors integrate the EnergyPlan with a mathematical model that analyzes the energy system from an exergetic point of view taking into account the exergy of the whole energy system and its components. Once multiple scenarios are obtained by EnergyPLAN, the exergetic model identifies the scenario characterized by the highest exergetic efficiency and the lowest energy wasting. This approach is a novelty since the “exergetic” optimization criterion coupled with EnergyPLAN software has never been utilized. Since the best energy system could not be economically attractive, this methodology might support Municipalities in setting up focused incentives to make the sustainable solutions the most cost effective too. The authors present a case study by applying the new methodology to the city of Pompeii. The results show that the best solution provides 21.0 MWe capacity of PV plant, integrated to 8.10 MWe of CHP plant. Due to a high value of critical excess electricity production, 10 MWe heat pumps must be installed. Finally, a solar thermal plant is installed. The proposed system could be only realized if new incentives are provided.

Recently, the booming electricity demand and intermittent energy has sharply increased the peak shaving pressure in China. However, for a majority of regional power grids in China, the installed capacity of flexible energy (like hydropower and pumped-storage) is small and the thermal plants are asked to respond the sudden load change at peak periods. The existing method based on specialist experience and historical information may generate inferior solutions and fail to reduce the peak pressure. Thus, a practical mixed integer linear programming (MILP) model is developed for unit commitment of thermal plants with peak shaving operation aspect in regional power grid lack of flexible hydropower energy, where the goal is chosen to minimize the peak-valley difference of the residual load series obtained by subtracting all the thermal generation from the original load curve while satisfying the necessary physical constraints. The MILP model is used to the thermal system in the China’s largest regional power grid, East China Power Grid. The simulations show that the MILP model can effectively smooth the residual load curve by gathering power generation of thermal plants at peak periods. Therefore, an alternative tool is provided to alleviate the peak pressure of thermal-dominant regional power grid in China.

Existing thermal power plants must be adapted to cooperate with wind farms and other renewable energy sources by improving their flexibility. The paper analyzes the improvement of the 200MWe block's flexibility by installing hot water storage tanks. The maximum increase in the block output resulting from the shut-off of low-pressure steam bleeds is calculated. During this period, the hot water from water storage tanks is supplied to the boiler. Hot water is accumulated in pressure water tanks during the low-load period of the unit. Water with design temperature in the feed water tank flows into the water pressure tanks to reduce the electric power of the unit in the off-peak night hours. The hot water accumulated during the night in storage tanks is used to feed the boiler during the period of peak demand for electricity. The reduction in the block electric power was calculated for various volumes and charging periods of the water storage tanks. A cost analysis was carried out to demonstrate the economic profitability of installation of pressure water accumulators. It is worth mentioning that hot water tanks may also be applied to fill the boiler evaporator with hot water before the start-up of the power unit from the cold state.

In this study, pinch analysis is employed to integrate energy in steam cycle of a 250 MW thermal power plant (TPP) located in Rajasthan state of India. To apply pinch analysis on steam turbine, all extractions exiting the turbine are considered as hot utility and feedwater as cold utility. Pinch analysis shows the potential savings in hot and cold utilities as 9.66% and 0.77%, respectively. Considering heat transfer across the pinch in condenser, heat available in boiler blow down and flowrates of extraction of low pressure (LP) turbine, six different energy integration schemes are proposed. Results show that extraction of LP turbine entering to LPH-1 is eliminated, which saves steam extracted from turbine for preheating the feedwater and thus, extra power is generated. It is also seen that flowrates from other two extractions of LP turbine decrease marginally. Amongst six energy integration schemes, the best one indicates that using pinch analysis, net generated power is increased by 0.55% and demineralized water demand is reduced by 57.6%. Further, exergy analysis of steam cycle is carried out and compared with that of most suited retrofitted scheme. Results of the present study are compared well with that of published literature.

The use of a low pressure economizer (LPE) is an effective way to recover waste heat from the exhaust flue gas in thermal power plants. In this paper, an improved bypass staged economizer scheme is presented for China's 600-MW ultra-supercritical power units. The simulation models of the bypass staged economizer and traditional LPE were established based on a 600-MW unit. The simulation results showed that when the presented economizer system was adopted, the temperature of the exhaust flue gas was reduced to near the flue gas acid dew point, thereby greatly improving the energy-saving effects. Compared with the traditional LPE system, the improved economizer system can reduce standard coal consumption rate by an additional 1.1 g/kWh. The bypass ratio under different loads could be adjusted to achieve the best energy-saving effect. The optimum bypass ratio was analyzed under different loads. The results showed that the improved economizer system had a better energy-saving effect by actively controlling the exhaust flue gas temperature.

The high-power mechanical pumps used in thermal power plants consume a considerable amount of electrical energy. Thus it is of great importance to improve the efficiency from every potential feature of such pumps. In this study, the clocking position of the pump, defined as the circumferential position of the vaned diffuser relative to the circular casing, is investigated to improve the hydraulic performance. Thereafter, the flow loss visualization method is employed to depict the loss caused by clocking positions with the help of entropy production theory based on computational fluid dynamics (CFD). The numerical results are then validated by experiments. At the design condition, the numerical maximum difference in the hydraulic efficiency is 2.61% while the head of each scheme meets the design requirement. The clocking position influences the total pressure loss coefficient more in the circular casing than other components, and the largest difference in the circular casing is 1.91%. Furthermore, the proven visualization method reveals that the clocking position introduces additional flow losses in the circular casing of the worst scheme, and even increases the loss in the vaned diffuser. This study can also provide a new perspective to investigate the optimal assembly strategy for other hydraulic machinery.

In order to evaluate the impact of ambient conditions on the performance of indirect dry cooling system quantitatively, an analytical model was established which combined the numerical simulation of thermo-flow performance of natural draft dry cooling tower and the thermodynamic analysis of water-steam system in a 660 MW thermal power generating unit. The model was verified by experimental results and practical operating data, respectively. Temperature and flow fields of cooling air, as well as the back pressure of turbine were obtained under various natural crosswind and ambient temperature conditions. Standard coal consumption rates were acquired accordingly. The results indicated that the back pressure and standard coal consumption rate increased with the ambient temperature and wind speed. The most additional 27.72 g/kWh of standard coal consumption rate can be caused by the natural crosswind and high ambient temperature for the investigated power generating unit. A sensitivity analysis was conducted and the results showed that the value of the standardized coefficients for natural crosswind speed and ambient temperature were 0.446 and 0.888, respectively. Therefore, though the natural crosswind could deteriorate the flow field of ambient air, the ambient temperature had a greater impact on the standard coal consumption rate.

As the share of intermittent energy sources is increasing, the dynamic modeling of thermal power plants including their power conversion system gets researchers' attention. Recent applications require transient simulations of high-pressure nitrogen closed Brayton cycle for which the ideal gas assumption is no longer verified. In this work, the REFPROP real gas equation of state and pressure drop correlations suitable for high Reynolds numbers have been implemented in the CATHARE-3 code. Moreover, new real gas turbomachinery and sonic flow models have been developed and integrated in the code. Relative errors obtained for the nominal state of a high-pressure nitrogen closed Brayton cycle are in the range −3%/+0.8%. A detailed analysis of real gas effects is carried out on the heat exchangers heat flux and the piping pressure losses. The new sonic flow computed during a loss of coolant accident is in the best possible agreement with literature experimental results. With regard to the turbomachinery, the new real gas model creates a pressure dependence that brings compressors closer to the choke region when the pressure drops in the cycle. This work is expected to provide an efficient and reliable simulation tool for transient analysis of real gas closed Brayton cycles.

The solar receiver performance has a direct impact on the CSP power plant performance and, thereby, its levelized cost of electricity. Improved receiver designs supported by new advanced numerical tools and experimental validation campaigns directly help to make CSP technology more competitive. This paper presents an experimental and numerical investigation of the influence of the cavity receiver radiative properties and the thermal power input on the Dish-Stirling performance. Three cavity coatings are experimentally investigated: the original cavity material (Fiberfrax 140), Pyromark 2500 and Pyro-paint 634-ZO. Moreover, simulations validated with the experimental measurements are utilized to define a higher performance cavity receiver for the Eurodish system. The results indicate that the absorptivity of the cavity should be as low as possible to increase the receiver efficiency whereas the optimum emissivity depends on the operating temperatures. If the cavity temperature is lower than the absorber temperature, low emissivities are recommended and vice-versa. All material/coatings analyzed for the cavity provide similar receiver efficiencies, being Fiberfrax 140 slightly more efficient. Finally, a total receiver efficiency of 91.5% is reached by the proposed Eurodish cavity receiver when operating under the most favorable external conditions.

The techno economic feasibility of offshore wind energy potential for Kuwait was assessed. The main objective was focused on selecting right locations for commercial wind mill erections. The measured wind speed from Directorate General of Civil Aviation, Kuwait for eight offshore stations during January 2012 to December 2015 was used and the parameters of Weibull distributions and wind power densities are estimated at an extrapolated elevation of 30-m from mean sea level. It is found that the best marine location was Beacon N6, just 3 km south of Boubiyan Island with wind power density of 583.2 W/m2 during summer. It was found that the wind power density near the coastal area peak in summer, which is good, since in summer, the demand for energy is high. The next highest wind power density was at South Dolphin and Ahmadi oil pier area, which is also closer to mainland. The wind power density was also found to be high at offshore locations such as Sea Island Buoy, Umm Al-Maradim, and Beacon M28 during winter. In Kuwait, the wave climate is moderate and the water depths are less than 20 m for most of the sites. Economic analysis is carried for a 50 MW offshore wind mill and is compared with 800 MW thermal power plant. From this analysis, it is found that power production/kWh from offshore wind turbines will be about 30% cheaper compared to the oil based thermal power plant.

In this work a decision making framework for the design of the flue gas treatment section of a power plant has been developed, including particle, NOx and SO2 removal operations. It has been applied to a coal based thermal power plant in Spain to select the optimal technologies and its sequence. Surrogate models for the treatments have been developed. The problem corresponds to a mixed integer non-linear programming one including catalytic and non-catalytic NOx removal, allowing various allocations for the catalytic technology, electrostatic precipitation and wet or dry SO2 removal. It is reformulated as a non-linear problem to evaluate bypass opportunities. The optimization suggests the use of electrostatic precipitation, followed by catalytic NOx removal and dry SO2 removal. Next, a coal blending problem has also been solved for two objective functions. When only treatment costs are considered, the use of imported coal is recommended, but an increase of 4% in its price can change the decision into the use of national coal. If the energy within the coal is added to the objective function, crude tar coal is included in the blend and imported coal is used to maintain the emissions within limits. Limestone Forced Oxidation is the selected technology.

Due to the intermittent nature of solar irradiance, solar power plants are usually equipped with energy storage systems. Suitable charge and discharge management of the storage systems can considerably help increase the reliability and profitability of the solar systems. In this regard, various optimization approaches, with their own strengths and limitations, have been employed by literature. Dynamic Programming (DP) is one of the fittest approaches for the wide range of engineering problems which exhibit the properties of overlapping sub-problems. DP is a simple, gradient-free, efficient, and deterministic optimization method that guarantees the optimal solution. However, this method has not been developed for multi-objective problems. This study develops a multi-objective DP method and employs it for the performance management of a solar power plant equipped with thermal energy storage system. “Daily electricity generation” and “daily revenue obtained from selling electricity” are considered to be the objective functions. The superiority of the developed method is shown through a comparison with one of the most commonly used multi-objective optimization approaches, NSGA-II. This comparison indicates that the multi-objective DP attains 3.0%–7.5% greater values of electricity generation and 3.1%–12.6% higher values of revenue than NSGA-II, for the different levels of solar radiation.

Made available in DSpace on 2022-04-29T08:39:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-05-15 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Waste heat emissions derived from cooling systems of the thermal power plant often discharged into rivers, lakes and seas, have been the direct cause of environmental problems for marine life. To control these wastewater discharges into the receptor water body, government regulations have been created to act as limiting factors for additional power generation from these plants. The problem can be solved with an organic Rankine cycle (ORC), which is considered a promising technology in electricity generation and an alternative to avoid the thermal pollution of aquatic ecosystems. The present work analyzes the use of an ORC system aiming to increase the thermal and overall efficiency of conventional operating systems without causing an additional thermal impact on marine species. This evaluation was based on the first and second laws of thermodynamics, applied to seven organic fluids (toluene, methanol, benzene, R11, R12, R113, R134a) and equations that linked the overall efficiency of the power plant with parameters of life quality in the rivers. Results showed that among the chosen organic fluids benzene produced the highest thermal efficiency for the ORC. Besides, an application of the proposed modelling in a thermal power plant localized near to Tubarão river, SC – Brazil was presented. Results showed that by using R113 as working fluid, it is possible to generate up to 1365.02 kWelec of additional electrical energy and increase both thermal and overall efficiency of a thermal power plant by up to 22.34% and 11.01%, respectively, without causing a thermal impact on the aquatic ecosystem. The best energy use was achieved by the recuperative ORC configuration. The Dissolved Oxygen Concentration (DOC) was reduced to 6.14 %day−1, which is consistent with the regulation of the Brazilian government regarding effluent discharges in lagoons, rivers and seas. On the other hand, considering the electricity cost at 0.16 US$kWh−1 and 5% as an annual percentage rate (APR), results in a payback period of approximately 5.3 years. Thus, the specific investment cost (SIC) of this technology was estimated at 1314.57 US$kWe−1. São Paulo State University (UNESP) Engineering School Energy Department Guaratinguetá Campus, Av. Ariberto Pereira da Cunha, 333 São Paulo State University (UNESP) Engineering School Energy Department Guaratinguetá Campus, Av. Ariberto Pereira da Cunha, 333

The benefits that may accrue for the operators of Solar Thermal Power Plants by integrating simulators to everyday operation and maintenance management is demonstrated by using a simulation environment allowing steady state and transient modelling. Two representative STPPs are used as test cases, namely a hybrid solar gas turbine plant and a solar steam turbine plant. The plants operation is simulated for different operating modes utilizing annual meteorological data. Component faults that may occur during operation, such as mirror soiling and misalignment are studied. The effects of different operating modes on performance and operability are established and evaluated. The effect of components degradation on performance is assessed, the overall plant performance deterioration is quantified, and the possibility for selecting optimal maintenance planning is discussed.

Operational flexibility of thermal power plants is urgently needed to maintain a balance between supply and demand in the power grid with high penetration of the intermittent renewable energy generation. A new coordinate control strategy was proposed and evaluated based on dynamic simulations in this study to enhance the operational flexibility of thermal power plants. The dynamic simulation model of the control object, a double-reheat coal-fired power plant, was developed and validated. The operational flexibility of the power plant was examined using the original control strategy, and results indicated that the reheat steam is seriously overheated when the power ramp rate increases. A new coordinated control strategy assisted by high-pressure extraction steam throttling was proposed to address the issue of reheat steam overtemperature and further increase the power ramp rate. The proposed control strategy obviously improved the control performance of thermal parameters, especially the reheat steam temperature. The change magnitude of reheat steam temperature is decreased by 3.0 °C. Moreover, the power ramp rate is increased from 1.5% to 4.5% Pe0 min −1 , which extremely enhances the operational flexibility. Furthermore, the proposed control strategy is compared with previous ones from the aspects of the flexibility and efficiency.

The flexible operation of thermal power plant has become a research hotspot for its safety and validity in eliminating power grid fluctuation from large-scale integration of renewable energy. Heat-power decoupling is effective technique to promote flexibility of combined heat and power plant. To address the insufficient dynamics investigation of combined heat and power plant under different heat-power decoupling strategies, an adaptive modeling approach is proposed. This method systematically fuses the mechanism analysis and data-driven fuzzy modeling to prepare for the controller design for rapid and deep load regulation in flexible operation. Firstly, the model structures with unknown parameters are determined by mechanism analyses to reflect the effects of various decoupling techniques on the characteristics of plant. Secondly, in view of the on-site data under wide load operation conditions, corresponding model structure is adaptively matched, and a new Takagi–Sugeno fuzzy modeling scheme depend on biquantum pigeon optimization algorithm is constructed for model parameters acquisition. The effectiveness of the proposed approach is illustrated based on a 350 MW supercritical combined heat and power unit. Simulation results illustrate that the adopted method can rapidly characterize dynamics of plant under different heat-power coupling conditions. All the model identification and verification errors in wide load operation conditions are less than 3.1% plant output, which reveals high modeling precision more than 97%. Thus, the established model provides solid foundation on highly matched controller for ensuring operational flexibility.

In view of the differences in transmission delay and transmission loss between heating network and power-grid in the integrated energy system, an ultra-short-term optimal scheduling energy management considering the characteristics of heating network is proposed in this pape. Based on graph theory, a heating network model suitable for system optimal scheduling is established. Considering the transient characteristics of the thermal medium temperature, the theoretical basis for judging the transient and steady-state heat transfer characteristics of the pipeline according to the scheduling period and the length of the pipeline is derived. The optimal operating state and daily operating cost of the equipment under three scenarios (considering the transient heat transfer characteristics of the heating network, considering the steady-state heat transfer characteristics of the heating network, and not considering the heat transfer characteristics of the heating network) are respectively compared. The calculation example analysis and verification show that the heat storage characteristics caused by the complex topology and transmission delay of the heat network change the matching of the supply and demand of the thermal power of the system, and the thermal power of the supply and demand side is no longer matched in real time. The ultra-short-term optimal scheduling energy management considering the transient heat transfer characteristics of the heating network has the regulation potential of the IES electric-thermal economic optimal operation under the excitation of time-of-use electricity price, and effectively makes use of the complementary characteristics of the electric and thermal systems to reduce the operation cost of the integrated energy system.

In conventional calcium looping (CaL) CO2 capture process, the heat of calcination is provided by burning additional fuel in the calciner that leads to thermal efficiency drop of the power plant. Coupling of CaL with concentrated solar power (CSP) can supply required heat and improve its drawback. In this study, a CaL-CSP system has been modeled to integrate with a 500 MW coal-fired power plant. Moreover, two steam cycles were designed to effectively recover available heat sources. The performance of the system was evaluated by employing energy, exergy and economic analysis. For CO2 capture efficiency of 93%, the calciner requires 1293 MWth thermal power which was supplied by heliostat field with efficiency of 88.56%. The net electrical efficiency of the overall system and the levelized cost of electricity were determined 33.22% and 120.27 $/MWh respectively. The results showed that the designed system does not impose any thermal efficiency drop on the power plant and its economic performance is competitive with other CO2 capture technologies. The exergy analysis indicated that the calciner side had a lower exergy efficiency (82.61%) in comparison with the carbonator side (88.51%) due to the higher exergy destruction in the calciner reactor and the compression unit.

The energetic and exergetic performance of a solar thermal power and ejector-absorption refrigeration system is investigated. R141b, R600a, R290, R717 and R143a were employed as the working fluids for ORC and NH3-LiNO3 was utilized in the ejector-absorption cycle for cooling production. The energetic and exergetic output of PTC driven combined power and refrigeration cycle were evaluated along with the calculation of thermodynamic irreversibility. The distribution of solar exergy input to the cycle in term of exergy produced, destroyed due to irreversibility, and loss due to thermal exhaust to the ambient was computed and compared with the traditional energy distribution. The maximum exergy was destroyed in the PTC where it amounts to 79.61% of the overall exergy destruction. The conversion of solar exergy input to the cycle exergy output was best (14.6%) for R141b fluid and worst (3.9%) for R143a fluid. Parametric analysis of the results reveals that Solar beam radiation (SBR), turbine inlet pressure (TIP), ORC pump inlet temperature, heat transfer fluid (HTF) temperature at the inlet of PTC, and the selection of ORC working fluid have the significant effect on the energetic and exergetic outputs of solar thermal power and ejector-absorption cooling system.

The coaxial borehole heat exchanger (CBHE) can effectively develop deep geothermal resources with larger heat exchange area than traditional U-tube BHE. However, few studies focus on its parameters optimization and temperature field dynamic response. Hence, an unsteady-state heat transfer model is established for a deep CBHE. The finite difference method is adopted to solve the model, and the model is validated with experiment data. The effects of key factors on the CBHE performance are comprehensively analyzed. Simulation results depict that the outlet temperature decreases greatly at the initial stage, and then remains relatively stable. There is a critical value for flow rate to obtain higher thermal power with appropriate pressure drop. The insulated pipe can significantly reduce heat dissipation of working fluid in central pipe. There is an optimal insulation length in terms of heat insulation effect and costs. The thermal conductivity of cement sheath has remarkable influence on the thermal process and partial cementing with high thermal conductivity cement is favorable. The temperature field analysis shows that the impact scope is limited, and the temperature in the reservoir before the next heating period would almost recover its original condition, verifying the sustainability of CBHE system.

In this study, the authors developed an Optimal Power Generation Mix model, which takes into account the supply chain of imported and domestically produced hydrogen, also modeling the intermittency of renewable energy at a 10-min resolution, and applied it to the case of Japan, to investigate quantitatively the possibility of achieving zero emission in 2050. Even if the costs of wind and solar PV decline drastically towards 2050 and the huge potentials that have been assumed in the literature are realized, the total system costs escalate significantly with very high shares of intermittent renewables. Since the use of hydrogen produced by excess electricity from renewable power generation sources can only make a slight contribution to reducing this escalation, it would be invaluable to introduce at least a significant amount of electricity generated by “zero-emission thermal power” technologies, including CO2-free imported hydrogen or conventional thermal power generation with carbon capture and sequestration (CCS). Nuclear power is also estimated as being effective in reducing the cost hike associated with achieving zero emissions. The results of this study could contribute to giving insights regarding global deployment of hydrogen-related technologies, as well as to presenting a frame of reference for Japan's future energy policies.

For parabolic trough solar collectors, several factors (such as the amount of the gas in the evacuated annulus, the absorber emissivity, the wind speed and temperature distributions of the absorber, the glass envelope and the heat transfer fluid) are critical to influence their heat losses and consequently their overall performance. Therefore, this study develops a mathematical model for thermal behaviors of parabolic trough solar collectors in consideration of these impact factors. Additionally, to validate this model, experimental data were measured for a test facility. This facility includes a utility-scale loop of parabolic trough solar collectors which can be applicable to solar thermal power plants. The comparison indicates a good agreement between predicted and measured temperatures of the heat transfer fluid at the outlet of the collectors. Using this model, parametric studies were conducted for impact factors. These factors are the pressure of the H2 or air from 0.01 to 1E5 Pa, the absorber emissivity from a measured basis to its four times, the wind speed from 2 to 12 m/s, and temperature distributions with and without the concentrated solar flux. Consequently, several conclusions were drawn by analyzing how they influence heat losses and further overall performance under specified boundary conditions.

A CO2 enhanced geothermal system (EGS) with multilateral wells is proposed to exploit hot dry rock (HDR) in this paper. For this EGS, several upper injection and lower production multilateral wells are sidetracked from one main wellbore in HDR. CO2 is injected from the injection multilateral wells into the reservoir and then extracts heat. Subsequently, high temperature CO2 is produced from production multilateral wells and returns to the surface through the insulated tubing in the main wellbore. In this study, a 3D fluid flow and heat transfer model for this CO2-EGS is established. The effects of key factors on the heat extraction performance of this CO2-EGS are studied. The performances of double-well and multilateral-well CO2-EGS are compared. The results indicate that multilateral-well CO2-EGS has a greater heat extraction performance than conventional double-well CO2-EGS. The lower production pressure, more multilateral wells and longer multilateral wells can improve CO2-EGS performance, while the lateral-well diameter has negligible effects on CO2-EGS performance. The injection mass flow rate and well spacing should be optimized to obtain a stable output thermal power and long enough service-time. This work offers good guidance for the optimization design of CO2-EGS with multilateral wells.

Renewable portfolio standard (RPS) plays a significant role in developing renewable energy. This study developed an evolution game model of power producers to analyze the symbiotic evolution between RPS and the electric producers’ behavior strategies, and discuss the impacts of the key institutional parameters on the dynamic evolution process of electric producers. To verify the theoretical results, simulation experiments and sensitivity analysis were conducted with meaningful results: Trading Tradable Green certificates (TGC) could become the common belief of all power producers, with the scientific design of institutional parameters. An optimal quota, higher unit fine, lower transaction cost and marginal cost difference of green and thermal power contribute to improving the effectiveness of RPS. This study could provide some scientific recommendations for government to design and construct RPS.

Existing hot dry rock geothermal projects are commonly confronted with some technical issues, such as corrosion and scaling, and water loss. To resolve these issues, the present work proposes a novel system for mining hot dry rock geothermal energy, in which a reservoir is combined with a heat pipe system. The new system encompasses a heat pipe placed in a single-well to extract hot dry rock geothermal energy, while an artificial reservoir is built around the main endothermic region of the well, which is permeable and saturated with carbon dioxide (CO2). This wellbore structure design may stimulate a stronger natural convection in the reservoir, resulting in a higher thermal power production. To evaluate the proposed system, an extensive numerical investigation was conducted. The comparison of the proposed system with the conventional downhole heat exchanger (DHE) system in terms of heat extraction performance indicates clear superiority of the proposed system primarily due to the associated thermosyphon effect of CO2 fluid in the reservoir. To better understand how operating and design variables affect the heat extraction performance of the system, a detailed sensitivity analysis was conducted taking into consideration a wide range of possible configurations and working conditions. The eventually obtained knowledge will guide the design of the system in practice.

This paper presents a model of a natural draft wet type cooling tower, which is based on the conservation laws of thermodynamics. The model assesses the cooling abilities of a tower, the evaporation rate, and the amount of required make-up water, all represented as a function of the atmospheric conditions. The purpose of the model is to estimate the effects of extreme weather conditions on the thermodynamic efficiency of a natural draft wet type cooling tower. World climate is changing and average temperatures are anticipated to rise in the near future, thus affecting the electrical energy generation. To that aim, we study the climate change effects on the ability of natural draft wet type cooling towers to reject heat and hence on the electricity generation of thermal power plants. Additionally, we perform cost-based analyses of a cooling tower considering the long-term projections for air temperature increase, and exemplify our model with reference to a location in France. The results show a remarkable drop in the cooling tower efficiency, and, hence, significant electricity generation losses even when a small increase of atmospheric temperature above the cooling tower design temperature occurs. Furthermore, the results of the cost-based analysis show that large electricity losses are expected. However, the performed cost-based analyses, considering climate change projections, show that even with the highest temperature increase, there is no need for additional tower height. In other words, the concrete costs outweigh the generated revenues from the curtailed power as result of insufficient cooling.

The article presents the technical - economic details of a hybrid power plant, towards 100% electricity production for the autonomous island of Sifnos, Greece, following the initiative of the Sifnos Island Cooperative (SIC) to claim the island's energy independence and a sustainable future for the local community. In the case of Sifnos, energy independency is achievable given the high wind potential and the availability of an appropriate site for the installation of a seawater Pumped Hydro Storage system. Despite the low power demand (annual peak demand 6.5 MW), pumped storage remains the optimum energy storage technology, with a set-up specific cost of 30 €/kWh of storage capacity. The project's economic feasibility is ensured with a selling electricity total price of 0.29 €/kWh, given the production specific cost (0.34 €/kWh) of the existing thermal power plant. The hybrid power plant anticipates to constitute the kernel of the SIC objectives for a general social and economic development for the local community. This can be approached with the re-investment of the project's profits for the development of essential technical infrastructure and the exploitation of the electricity production surplus, combined with energy saving or smart-grid techniques, to foster new professional activities.

This study proposes a slack-based endogenous directional distance function model (SBEDDF) to assess the environmental impact of China’s power generation industry. By selecting directional vectors according to slack values and endowing them with norms, this model guarantees that unit invariance and efficiency value measures are suitable for economic interpretation. The results of this study indicate that the environmental efficiency of China’s power generation industry is low and varies considerably from one region to another. The optimal approach to reduction of emissions is unique for each region. For example, in Guangxi, reducing SO2 emissions is the priority, while in Shanxi, NOx emissions need to be targeted. The results of the Tobit regression analysis indicate that the power function of unit elasticity fits the environmental Kuznets curve of the power industry well. These results demonstrate that it is prudent for environmental administrators to tailor emission reduction standards and incentive policies to the prevailing circumstances in a region.

High energy consumption remains a challenge for the amine-based post-combustion CO2 capture in thermal power plants. Process intensification is a feasible way to reduce heat requirement effectively in a CO2 capture process. In this work, we propose a hybrid post-combustion CO2 capture process configuration, aiming at lower energy consumption compared to conventional ones. The proposed process configuration features a pre-concentrating membrane, an intercooler, a rich solvent split configuration, and an air stripper. Typical aqueous monoethanolamine (MEA) with 30 wt% concentration is selected as absorbent. A rigorous rate-based method with corresponding thermal dynamic and chemistry models are employed to calculate the performances of the proposed CO2 capture process in Aspen Plus. Impacts of single process intensification configuration are analyzed separately to identify quantitative contribution of each of them to the overall performance improvement. Five different processes are presented and the reboiler duty can be reduced to a minimum in the last process due to the combination of the four configurations. Results show that a reboiler duty as low as 2.5 MJ/kg CO2 can be achieved by parametric optimization, which is 28% lower than that of conventional processes, leading to a reduction of 1.9% points in net power efficiency penalty.

Boiler in thermal-power-plant plays important role in generation of power. Conventional subcritical-boilers use single-loop controls which are less efficient. An effective control of temperature and pressure of boiler is necessary to enable safe power generation. This article discusses application of three different multivariable-control strategies, namely, PID (Proportional-Integral- Derivative), MPC (Model Predictive Controller) and Inverse-decoupling-control to the individual units of boiler (economizer, drum, super-heater) as well as to the integrated boiler unit of the coal-fired thermal-power-plant separately. The mathematical-model derived based on mass-balance and energy-balance equations of economizer, drum and superheater units are used for the synthesis of controller. The non-square nature of mathematical-model carries complexity in the design of controllers. The performances, based on minimization of objective-function containing closed-loop error along with the control-effort of individual and integrated units, of the boiler using IMC (Internal-Model-Control) based PID, Inverse-decouple and MPC in the presence of disturbances are analyzed and compared. The results show that multi-loop control of integrated units ensures asymptotic-stability compared to unstable single-loop control and the controller needs to take less effort in the case of the integrated unit compared to the individual units. The results suggest for implementation of integrated multi-loop control instead of controlling individual boiler units.

The Calcium-Looping process is a promising thermochemical energy storage method based on the multicycle calcination-carbonation of CaCO3-CaO to be used in concentrated solar power plants. When solar energy is available, the CaCO3 solids are calcined at high temperature to produce CaO and CO2, which are stored for subsequent utilization. When power is needed, these reaction by-products are fed into a carbonator reactor where energy is released from the exothermic carbonation reaction. In comparison with currently commercial energy storage systems, such as solar salts, the Calcium-Looping process presents several benefits such as the feasibility to work at significantly higher power cycle temperatures, a higher energy storage density and the possibility to store energy in the medium-long term. The present manuscript analyzes a number of novel Calcium-Looping configurations for energy storage combined with CO2 cycles in a solar tower plant. The high overall efficiencies achieved (32–44%, defined as the ratio of net electric power production to net solar thermal power entering the calciner) indicate a potential interest for the integration of the Calcium-Looping process in Concentrating Solar Power Plants, although major technological challenges related to the design of the solar receiver and of the high temperature solids handling devices remain to be faced.

There had been several processes for recovering exhaust gas heat at the boiler cold-end, thereby increasing the efficiency of a thermal power plant. However, the existing processes encounter a great challenge on the heat exchanger, wherein the acid corrosion, fouling and abrasion of heating surfaces are inevitable because it is working in very low temperature flue gas. In this paper, a novel hot air recirculation (HAR) process is advanced to avoid these tricky problems. To demonstrate the thermo- and techno-economic performance of the HAR, an in-service 600 MW brown-coal-fired power unit was used as a reference unit for analyses. Meanwhile, the performance of the conventional bypass flue (CBF) process was also calculated for comparison. The results show that, when recovering the boiler exhaust heat from 148 °C to 90 °C, the net coal savings, initial capital cost and payoff period of the HAR are 7.31 g/(kW·h), 2.522 million USD and 1.08 years, whereas the corresponding results of the CBF are 6.79 g/(kW·h), 6.074 million USD and 3.24 years. Overall, the HAR can benefit the power plant from a safe and reliable operation, a greater net coal savings and a better techno-economic performance, exhibiting an obvious superiority in the similar processes.

Restricted by the return water temperature of district heating network, conventional cogeneration plants cannot efficiently recover the low-grade waste heat of exhaust steam. A novel cogeneration technology based on absorption heat exchange (Co-ah) has been successfully applied to waste heat recovery of thermal power plants, enlarging the heating capacity of district heating network. In this paper, a modular simulation code is developed to simulate and analyze the complicated Co-ah system. The establishment and solution of system equations are accomplished automatically, so any changes in operating conditions or system configuration can be easily dealt with. The theoretical models are validated by the practical operating data. A comparison between the conventional cogeneration system and Co-ah system is made. With the help of the absorption heat pump, the Co-ah system recovers more waste heat from the exhaust steam and exhibits better exergetic and economic performances than the conventional system. The effects of three key parameters including back pressure, extract flow rate and extract pressure on cogeneration performances are analyzed in details, providing a guide for regulation strategies when operating conditions vary.

In this paper, we present a new method to determine the optimal design conditions of a supercritical CO2 recompression Brayton cycle with dry cooling based on plant location. These power cycles are gathering high interest in concentrated solar thermal power technologies, which are most likely to be deployed in arid areas where dry cooling is a strategic choice. However, the usual high ambient temperature associated with these locations affects negatively the cycle performance. The key selection of two design parameters, the recompression fraction and the compressor inlet temperature, can minimise this negative effect. The method presented here allows the adjustment of these two parameters maximising the annual generation of electricity and cycle efficiency simultaneously. The optimisation process analyses the drop in the cycle performance due to the yearly variation of ambient temperature at the specific location. To reduce the computational effort required, polynomial regressions extrapolate the results from a reduced set of design-point and off-design cycle simulations in a wide range of ambient and compressor inlet temperatures. As an example, the method is applied to three different locations demonstrating the existence of optimal design conditions and justifying the need to adjust these two key parameters for each specific location.

Concentrating solar thermal power plants rely in thermal energy storage systems in order to provide a stable power supply. However, they might not been able to meet power plant demands, mainly because of their storage sizes which are restricted due to economic reasons. One way of mitigating this effect is to control in an optimal way the charging and discharging processes. For the design and validation of advanced control strategies, an accurate dynamic model is essential. For this reason, a dynamic thermal energy tank model intended to be used in concentrating solar thermal power plant models is presented in this paper. The developed tank model is validated in charging and discharging processes and also at rest state in order to validate thermal losses dynamics. Simulation results are compared against experimental data from the CIEMAT-PSA molten salt testing facility.

Nuclear superheated-steam supply systems (Su-NSSS) produces superheated steam flow for electricity generation or process heat. Although the current Su-NSSS control law can guarantee satisfactory closed-loop stability, which regulates the neutron flux, primary coolant temperature and live steam temperature by adjusting the control rod speed as well as primary and secondary flowrates, however, the control performance needs to be further optimized. Motivated by the necessity of optimizing the thermal power response, a novel multi-layer perception (MLP) based model predictive control (MPC) is proposed in this paper, which is constituted by a MLP-based prediction model and the control input designed along the direction opposite to the gradient of a given performance index. It is proved theoretically that this MLP-based MPC guarantees globally-bounded closed-loop stability. Finally, this newly-built MLP-based MPC is applied to the thermal power control of a Su-NSSS, whose implementation is given by forming a cascaded feedback control loop with the currently existing Su-NSSS power-level control in the inner loop for stabilization and with this new MPC in the outer loop for optimization. Numerical simulation results verify the correctness of theoretical result, and show the satisfactory improvement in optimizing the thermal power response.

Non-imaging concentrators based on optical waveguides have the potential to provide low cost solar collection for concentrated solar thermal applications through the elimination of moving parts and tracking structures. The primary working principle involves collection and transport of light through total internal reflection within an optical waveguide onto thermal receivers. This study explores the optical and thermal transport characteristics of radial waveguides integrated with a linear receiver. An analytical closed-form solution for the coupled optical and thermal transport of solar irradiation through a radial planar waveguide concentrator integrated with a linear receiver is developed. The effects of various design and operating parameters on the system performance, which is quantified in terms of net thermal power delivered, aperture area required and collection efficiency are discussed. Design constraints due to thermal stress, maximum continuous operation temperature and structural loading were considered to identify feasible waveguide configurations. A cost analysis is conducted to determine the preferred design configurations that minimize the cost per unit area of the radial waveguide concentrator-receiver system. Optimal design configurations that result in the minimum levelized cost of power (LCOP) are identified for thermal desalination and concentrating solar power generation applications.

Wide-range and frequent operation changes have become a common phenomenon with thermal power plants in the context of fast penetration of intermittent renewable power. Performance monitoring at transient states is more important to the safety and high efficiency of power plants. Data quality is essential for conducting dynamic performance monitoring, and dynamic data reconciliation (DDR) provides great potential to enhance quality of measured data at transient states. In this paper, a moving window based approach to dynamic data reconciliation is proposed for a real coal-fired power plant using high sampling operational data. Firstly, dynamic characteristics of the system are discussed, taking account of the equipment accumulation in DDR problems. Results of case studies indicate that the data accuracy of measured mass flow parameters are enhanced effectively after DDR, and better results are obtained with the increasing time window size. Comparison with steady state data reconciliation approach is also carried out to indicate the enhanced effect of the DDR approach for the performance monitoring of a real power plant.