Conventional Thermal Power Plants Research Articles

Reliability assessment of solar photovoltaic systems based on fuzzy fault tree analysis

Solar photovoltaic (SPV) systems are widely used as a renewable energy source to produce electricity to endusers. SPV system convert free and unlimited sunlight into electricity without carbon dioxide emission or any other air pollutants. The stochastic nature of SPV system may be responsible for degradation of performance in terms of availability, production, etc. Therefore, the assessment of the performance measures like reliability and quality of its components is vital concern that may open the new vista of research. There are various reliability assessment techniques used in conventional (thermal power plant, hydropower plant, nuclear power plant, etc.) and non-conventional power system (SPV power plant, wind power plant, etc.) like Fault Tree Analysis (FTA), Failure Mode and Effect Analysis (FMEA), etc. FTA is one of the powerful reliability assessment techniques, which gives modes of the failure and its consequences, that are demonstrated on SPV systems. FTA can further be broadly classified into two: qualitative and quantitative analysis. Qualitative FTA can be solved by determining a minimal cut set (MCS) and quantitative FTA can be solved by calculating the failure probability of each the basic event. In conventional FTA failure probability of each event must be known, to assess for quantitative FTA. However, to quantify probabilistic failure, data of all basic events seem to be inadequate. To overcome this problem, conventional FTA may be integrated with fuzzy linguistic scale method. In this research work, failure possibilities in terms of a linguistic variable of unknown failure data for all basic events, which lead the Top Events for SPV systems are assigned by the experts from academics, research, industries and practicing engineers. For Aggregated fuzzy number based on expert’s opinion, a consistency agreements method is used. Fussell-Vesely (F-V) importance measures is also implemented to rank the basic events and MCS to apportion the most critical event.

Energy integration in boiler section of thermal power plant

Abstract: In the present work systematic analysis is carried out for retrofitting of boiler section of the conventional thermal power plant of 250 MW capacity with the aim to recover maximum amount of waste heat available in it. Lignite coal is used in this plant as a fuel. For the existing system, pinch point, minimum hot and cold utility requirements are found as 972 °C, ‘0’MW and ‘11.09’MW, respectively. Pseudo-pinch point is also found at 272 °C and heat flow through it is 9.11 MW. It is observed that in the existing plant exit temperature of flue gas through the stack is restricted by dew point of SOx to prevent corrosion in the stack. Dew point of SOx in flue gas is predicted as 122 °C. Further, heat from boiler blowdown can also be extracted. Considering waste heat of flue gas as a result of dew point as well as boiler blowdown six different energy integration options are proposed for retrofitting of boiler section. Detailed design and economic analyses are carried out for all these options. Different criteria such as location of additional heat exchanger, amount of flue gas and exit temperature, environmental aspects, %energy savings and maximum temperature across additional heat exchangers are envisaged to choose best retrofitting option. Results of the best option are compared with that of published work.

Reliability and Optimization Strategy in an Interconnected Network at a Wind Farm

Wind power plants are increasingly integrated into the power grid to reduce the environmental impact of conventional thermal power plants. Due to wind speed uncertainty, the problem of the intermittence and fluctuation of wind energy production causes a risk for interconnected electrical networks. Several papers try to solve this problem using various prediction methods. This paper presents the strategy of integrating a wind farm into an electrical network, based on the calculation of the electrical network parameters using the probabilistic distribution of wind. In order to validate the results obtained, the calculation of optimal power flow (OPF) is essential since it allows calculating the electrical energy flow between buses at a low cost and without the risk of grid disturbance. The solution to the OPF problem is implemented on MATLAB using the IEEE 24-bus standard electrical network.

Power generation from fluegas waste heat in a 500 MWe subcritical coal-fired thermal power plant using solar assisted Kalina Cycle System 11

This paper proposes a solar assisted Kalina Cycle System 11 (KCS 11) driven by fluegas waste heat of 500 MW Subcritical (SubC) coal-fired thermal power plant for additional electrical power generation. A computer simulation programme has been developed in MS-Excel and VBA to calculate and optimize system performance at different conditions. Results show that net electric power generation of about 516.52 kWh can be added with main plant generation for improving the plant net energy and exergy efficiencies by about of 0.040% and 0.036% point, respectively. This will reduce the annual CO2 emissions by about 1008.28 ton. Solar assisted KCS11 is more energy efficient but less exergy efficient compared to standalone KCS11. About 0.76 is the optimum ammonia mass fraction that yields the maximum efficiency at the operating pressure of 17.54 bar. System performance increases with increase in cooling water flow rate and is optimum at 92.80 kg/s. Power generation cost and payback period of the proposed system are about of Rs. 2.163 per unit generation and 12.44 years, respectively. The levelized cost of electricity (LCoE) for additional generation by solar heater is about Rs. 10.99 per kWh which is about 8.80% lower than conventional solar thermal power plant.

Peak shaving operational optimization of supercritical coal-fired power plants by revising control strategy for water-fuel ratio

Electricity generated from renewable energy source fluctuates heavily and can hardly be predicted. The peak shaving (or load cycling) operation of conventional thermal power plants is an effective means to mitigate the mismatch between electricity demands and supplies. Therefore, determining how thermal power plants can operate in a flexible and effective mode is an urgent issue that should be addressed. For thermal power plants, new methods and strategies need to be proposed to face the challenge of the integrating flexibility and energy saving into transient processes. Dynamic performances of thermal power plants during load cycling processes are affected by the coupling of the thermal system and the control system. Feasible approaches from optimizing the coordinated control system (CCS) may radically enhance the peak shaving capacity of thermal power plants. The heat storage in a coal-fired power plant, including heating surface metals and work media, varies with the load rate of the plant. During cycling load operations, the real-time heat storage value of one unit differs from that of the corresponding steady state load command rate. This difference hinders the flexibility of one unit and affects its economic performances during cycling processes. In this paper, a revised water fuel ratio (WFR) control strategy based on heat storage difference was proposed and tested on established coal-fired power plant models. Results show that the accumulation deviations of load rate command and real-time load rate are considerably reduced during load cycling processes when the proposed WFR control strategy is introduced. The revised WFR control strategy diminishes the difference between the target and the actual total power output. When the load cycling rate varies from 10 to 30 MW min−1 between 50% and 100% THA, the standard coal consumption variation rate (Δbs) decreases by 0.31–1.01 g kW−1 h−1 during loading up processes, and decreases by 0.26–1.69 g kW−1 h−1 during loading down processes.

How low can you go? The importance of quantifying minimum generation levels for renewable integration

One of the significant limitations of solar and wind deployment is declining value caused by the limited correlation of renewable energy supply and electricity demand as well as limited flexibility of the power system. Limited flexibility can result from thermal and hydro plants that cannot turn off or reduce output due to technical or economic limits. These limits include the operating range of conventional thermal power plants, the need for process heat from combined heat and power plants, and restrictions on hydro unit operation. To appropriately analyze regional and national energy policies related to renewable deployment, these limits must be accurately captured in grid planning models. In this work, we summarize data sources and methods for U.S. power plants that can be used to capture minimum generation levels in grid planning tools, such as production cost models. We also provide case studies for two locations in the U.S. (California and Texas) that demonstrate the sensitivity of variable generation (VG) curtailment to grid flexibility assumptions which shows the importance of analyzing (and documenting) minimum generation levels in studies of increased VG penetration.

Load Disturbance Rejection Based PID Controller for Frequency Regulation of a Microgrid

<p>Today’s world is very much concerned to reduce green house gas emission from the conventional thermal power plants as cutting down emissions from transport and heating sector may not be realistic in the near future. To reduce pollution from electrical power sources, the world is now marching towards usage of renewable energy sources (RESs). These sources being small in capacity are mostly connected at the distribution voltage level. This indirectly reduces transmission and distribution losses as the sources are around the load. This distribution system having small scale energy sources is called as a microgrid or active distribution network. Microgrid operates generally in a grid connected mode. However, circumstances such as fault, voltage sag and large frequency oscillations in the main grid may force the active distribution network to be disconnected from the main grid and operate as an isolated microgrid . During this isolation there will be change in power output from the controllable microsources which are to be regulated properly to have a stable operation in regard to power balance and frequency of operation within the isolated microgrid. An autonomous isolated microgrid comprising both controllable & uncontrollable sources. Like solar, wind, diesel generator(DG), aqua electrolyzer(AE), fuel cell(FC), a battery energy storage system(BESS), and fly wheel(FW) are considered. Solar, wind, DG and FC are power generating source & BESS, FW, AE as energy storage element. The generated hydrogen by an AE is used as fuel for a FC. The power system frequency deviates for the sudden change in load demand and the real power generation. The output power of DG, FC, BESS, FW and power absorbed by AE is regulated by using controller such that frequency of the system is controlled. Controller used is proportional plus integral plus derivative (PID). Load Disturbance Rejection(LDR) is used for tuning of controller gains of the proposed hybrid system. This uses the chien-hornes-resnick(CHR) setting with 20% overshoot. Design of p-f droop(frequency regulation parameter) for different controllable source in microgrid using bode plot stability criterion. The system response with Modified LDR based controller, LDR based controller and classical controller are compared. Investigation shows that Modified LDR based controller gives best response amongst these three methods.</p>

Utilisation of ultra‐capacitor in load frequency control under restructured STPP‐thermal power systems using WOA optimised PIDN‐FOPD controller

This study addresses the impact of ultra-capacitor (UC) on load frequency control of a restructured two-area multi-source system, incorporating conventional thermal and solar thermal power plant (STPP). The thermal system consists of single reheat turbine, appropriate generation rate constraint and governor dead band. Two generating companies and distribution companies are considered in each area. Maiden attempt has been made to use a cascade combination of integer-order (IO) proportional–integral–derivative with filter and fractional-order proportional–derivative (PIDN-FOPD) controller. Performance comparison of some commonly used IO controllers with proposed PIDN-FOPD controller reveals superiority of the latter in terms of peak deviations and settling time in policy schemes like poolco, bilateral and contract violation. A more recent optimisation technique called Whale optimisation algorithm (WOA) is successfully used for simultaneous optimisation of above controllers. Effect of UC using PIDN-FOPD has been studied for above policy schemes and analysis explores that use of UC improves the system dynamics. Sensitivity analysis reveals that WOA optimised PIDN-FOPD gains and system parameters are robust. It is also proved that PIDN-FOPD parameters obtained at nominal distribution companies participation matrix (DPM) are fit enough and parameters need not be optimised for change in DPMs.

Experimental study of large temperature lift heat pump (LTLHP) in CHP system

Combined heating and power (CHP) system is one of most promising ways for district heating, however, more than 20% of heat gained in the boiler is discharged to atmosphere directly by the cooling tower. A new absorption heat pump named LTLHP adopting the lithium bromide aqueous solution as working pair is invented for heat recovery at the thermal power plant, and its temperature difference between the evaporator and condenser could reach 50°C without risk of crystallization. The concentration difference of lithium bromide solution is 3.58% for a satisfying COP (coefficient of performance) without the risk of crystallization, which is far lower than that of a conventional absorption heat pump. The LTLHP is also experimented at a thermal power plant with double 330 megawatt steam turbines. The mean COP could reach 1.51 during the whole heating period, and 9.5×10^6kg of coal could be saved annually, and the index of coal consumption for heating at the thermal power plant could be reduced to 14.0kg/GJ, which is far lower than that of a conventional thermal power plant (18.0kg/GJ).

Preliminary investigation on the feasibility of a clean CAES system coupled with wind and solar energy in China

Compressed air energy storage (CAES) is a method of energy storage which can convert the surplus power to the internal energy of compressed air, and regenerates electricity whenever power is needed. A clean CAES system coupled with wind and solar energy was developed to solve the dependence of traditional CAES system on fossil fuels in China. The operating variables of the hybrid system include heat exchanger effectiveness, ambient temperature, mass flow rate, total pressure ratio and compressor/turbine stages. The effect of these variables on the system performance was evaluated, including output power, overall efficiency, energy ratio (ER) and heat ratio (HR). The parameters, delineating criteria of the potential development localities for the hybrid CAES system sites, such as solar and wind energy resources, abandoned cavities of mines resources used as compressed air containers and the distribution of cross-transmission lines in China were investigated. By this research, it was found that more than 13 major zones were of the capability to support the hybrid system in China. Finally, the environmental and economic benefits of this CAES system were calculated, comparing to the conventional thermal power plants; restrictions and policy supports of the CAES systems in China were discussed as well.

WITHDRAWN: Nuclear and renewable energy in Iran: Nuclear challenges and opportunities

Electricity generation nominal capacity of the power plants in Iran has reached to more than 74 GWe last year. The portion of nuclear and renewables including hydropower is about 17%. Considering environmental impact of conventional thermal power plants, the country is going to increase the share of nuclear (1.5%) and renewable energy (15.5%) resources in comparison with fossil fuels. In this study, the status of renewable and nuclear energy in Iran is reviewed and the challenges of nuclear energy development are elaborated. Furthermore, the new expected opportunities of renewable and nuclear development such as the international cooperation based on joint comprehensive plan of action (JCPOA) are also dealt with.

The thermoelectric generators use for waste heat utilization from conventional power plant

On the base of available data, it is estimated that the industrial approx. 20-50% of the energy is removed into the atmosphere as waste heat include in the form of hot flue gases, cooling water, the heat losses from the equipment hot surfaces or heated products. However, according to the data from the US market in 2010, in the form of waste heat is emitted more than 96 · 106 TJ annually (2.7 · 1010 MWh), means more than 57% of the produced energy. According to statistics, currently the energy production in the US amounts to approx. 26% of the world's energy production. Assuming the same indicators, the total annual amount of waste heat in the scale of the world equals 370 · 106 TJ (10.4 · 1010 MWh). One of the ways to increase the energy efficiency of manufacturing processes and reducing energy consumption and negative impacts to the environment is the use of waste energy [1,2,3] In this work it was investigated the possibilities of the waste heat utilization from conventional thermal power plant using thermoelectric generators, the operation of which is based on the Seebeck effect.

Techno-economic analysis of wind power generation for selected locations in Jordan

The aim of the present work is to develop a simple model to assess the capacity factor and predicted costs of wind energy in pre-selected five locations in Jordan. The simulation model is based on calculating the Weibull parameters and the annual electrical energy generated using different commercial types of wind turbine generators (WTG). For each site, detailed analysis was conducted using the developed model to calculate the capacity factor and the final unit cost of electricity (COE) for different types of commercial wind turbines. By merging final values of both factors, the best location and most suitable wind turbine could be defined. The estimated cost of electricity produced by wind energy ranged between 0.0259 and 0.0498 US$/kWh for the best site. While for other sites and wind turbine models, the cost may reach 0.2220 US$/kWh, which is still far less than those incurred in Jordan during 2013 using conventional thermal power plants firing diesel and/or heavy fuel oil. The obtained results are comparable with those published in the open literature for the Middle East region and worldwide. It is believed that such results could benefit not only researchers in this field but also policy makers, developers and investors planning to harness wind energy sources within the Middle East region.

The sustainable future of hydropower: A critical analysis of cooling units via the Theory of Inventive Problem Solving and Life Cycle Assessment methods

There is a growing public concern on the environmental pollution emitted from conventional thermal power plants. As a result, priority has been given to the development of clean energy, which leads to less pollution and fewer emissions to the environment. Hydropower, as a clean and renewable energy, plays a critical role to mitigate environmental issues associated with the power generation industry. This paper presents a theoretical analysis of hydropower generators in a comprehensive manner (including environmental and technological perspectives) via multiple methods of Theory of Inventive Problem Solving (TRIZ), Life Cycle Assessment (LCA) and sensitivity analysis. This study aims to investigate the sustainable development path of hydropower. This provides useful inputs to select the more appropriate type of generator according to the status quo of product development with a special attention to the environmental performance. Results show that the evaporative cooling generator is a better choice with less greenhouse gas emission (a total of 2.59*10−1kg CO2eq/kWh) than air cooling generator (a total of 6.04*10−1kg CO2eq/kWh). According to the evaluation of technology readiness and scenario analysis, the advancement of technology can also make a contribution to the economic development. These findings are useful for policy making on choosing the appropriate type of cooling system as well as hydropower system.

Моделювання та оцінка сценаріїв довгострокового розвитку атомної енергетики України

The paper presents the results of modeling and comparative analysis of long-term scenarios of the expansion of the generating capacities of Ukraine's Power System assuming decommissioning or extension of nuclear power plants' (NPPs) life. Development of scenarios and model calculations was carried out using the optimization modeling tool WASP-Ukraine, developed on the basis of IAEA software WASP-IV designed to find the economically optimal generation expansion policy within user-specified constraints. The model WASP-Ukraine is based on linear programming technique. Modeling baseline and alternative scenarios made for the period up to 2030 and the base year is 2014. The study examined six scenarios assuming decommissioning and extension of NPP life in accordance with international practice. The share of nuclear power in electricity production in Ukraine in 2030 under different scenarios varies from 11% to 48%. In the scenarios, which minimize the role of nuclear power, compensation of decommissioned NPP is provided by renewables or by conventional thermal power plants. Comparative analysis of the scenarios is conducted by four criteria: cost efficiency (average production cost of electricity generated in a power system); environmental sustainability (total emissions of sulfur oxides (SO2) and nitrogen oxides (NOx)); reliability of the power system and electricity supply (aggregated loss of load probability (LOLP) and the energy not served (ENS) indicators); provision of power plants with primary energy resources (steam coal). The comparative analysis proved that scenarios assuming extension of NPP life are more acceptable and efficient by all selected criteria comparing to those assuming decommissioning of NPP after their life period. Thus, maintaining the dominant role of nuclear energy in Ukraine's power balance at least until 2030 is justified.

District heating and cogeneration in the EU-28: Current situation, potential and proposed energy strategy for its generalisation

<p class="Textoindependiente21"><span lang="EN-US">Yearly, EU-28 conventional thermal generating plants reject a greater amount of energy than what ultimately is utilised by residential and commercial loads for heating and hot water. If this waste heat were to be used through district heating networks, given a previous energy valorisation, there would be a noticeable decrease in imported fossil fuels for heating. As a consequence, benefits in the form of an energy efficiency increase, an energy security improvement, and a minimisation of emitted greenhouse gases would occur. Given that it is not expected for heat demand to decrease significantly in the medium term, district heating networks show the greatest potential for the development of cogeneration. However, to make this happen, some barriers that are far from being technological but are mostly institutional and financial need to be removed. The purpose of this review is to provide information on the potential of using waste heat from conventional thermal power plants (subsequently converted into cogeneration plants) in district heating networks located in the EU-28. For this, a preliminary assessment is conducted in order to show an estimate of the cost of adopting an energy strategy in which district heating networks are a major player of the energy mix. From this assessment, it is possible to see that even though the energy strategy proposed in this paper, which is based on a dramatic increase in the joint use of district heating networks and cogeneration, is capital-intensive and would require an annual investment of roughly 300 billion euros, its adoption would result in a reduction of yearly fuel expenses in the order of 100 billion euros and a shortening of about 15% of the total final energy consumption, which makes it of paramount interest as an enabler of the legal basis of the “Secure, Clean and Efficient Energy” future enacted by the EU-28 Horizon 2020.</span></p>

Simultaneous Optimisation and Integration of Igcc Plant Using Graphical Method

As a promising green technology, Integrated Gasification Combined Cycle (IGCC) plant is more efficient and low-pollution electricity generation choice than conventional thermal power plants. Its process is mainly consist of the gasifier, the air separation unit and the combined cycle unit. Going through those key blocks, the fuel, such as coal and biomass, could be converted to syngas and further combusted for power generation. In order to be a viable technology, the bottleneck is located on the high energy production cost, which could be overcame by improving the plant efficiency through process optimisation and Integration. The opportunity and challenge are given by the complicated configuration and extreme operation conditions, which also demands a flexible and robust IGCC plant simulation to complete deep process analysis. In this work, a novel simplified IGCC mathematical model is proposed considering thermodynamics constraints with energy and mass conservation. The gasification is simulated based on the principle of Gibbs free energy minimisation, which holds the good feature of avoiding potential bi-level optimisation problem. The proposed gasification model results in syngas composition similar to the experimental data provided in literature. Meanwhile, the cryogenic air separation unit is selected with the double distillation column configuration, which is simulated considering the novel simplification of thermal coupled distillation columns. What is more, the combined cycle unit is simulated with isentropic assumption plus efficiency to complete the process. To validate the novel simplified IGCC model, one base case is built and compared with literature data. Another highlight of this work is the simultaneous optimisation and integration methodology instead of conventional sequential one, which gives more guarantee for achieving global optimal solution. If the ideal property assumptions are occupied, a graphical approach could be generated for the simultaneous optimization and integration of IGCC plant. The best material and energy integration scheme in proper operation condition could be selected considered with respect to the overall thermal efficiency of the IGCC plant. The good performance is shown by about 10 % power increment compared with the base case in the case study.

Solar photovoltaic system design optimization by shading analysis to maximize energy generation from limited urban area

In the urban areas the demand of solar power is increasing due to better awareness about the emission of green house gases from conventional thermal power plants and significant decrease in the installation cost of residential solar power plants. But the land cost and the under utilization of available space is hindering its further growth. Under these circumstances, solar photovoltaic system installation needs to accommodate the maximum number of solar panels in either roof-top or land-mounted category. In this article a new approach is suggested to maximize the total number of solar panels in a given area with enhanced energy output without compromising the overall efficiency of the system. The number of solar panels can be maximized in a solar photovoltaic energy generation system by optimizing installation parameters such as tilt angle, pitch, gain factor, altitude angle and shading to improve the energy yield. In this paper mathematical analysis is done to show that the capacity and generated energy can be enhanced by more than 25% for a given land area by optimization various parameters.

Quantifying the water–energy nexus in Greece

ABSTRACTIn this paper we provide an assessment of the water–energy nexus for Greece. More specifically, the amount of freshwater consumed per unit of energy produced is determined: for both conventional (lignite, diesel and fuel oil-fired) and advanced (combined operation of gas turbine) thermal power plants in the electricity generation sector; for extraction and refining activities in the primary energy production sector; and for the production of biodiesel that is used as a blend in the ultimately delivered automotive diesel fuel. In addition, the amount of electricity consumed for the purposes of water supply and sewerage is presented. In view of the expected effects of climate change in the Mediterranean region, the results of this study highlight the need for authorities to prepare a national strategy that will ensure climate resilience in both energy and water sectors of the country.

The impact of re-entrainment on the electrocyclone effectiveness

Abstract The problem of fine particle gas cleaning is especially actual at the present time. This is due to the need to capture the desired product and waste gases cleaning. In both cases, the equipment should provide maximum collection efficiency. Cleaning of gas from thermal power plant (TPP) fly ash is serious problem. Coal-fired thermal power plants provide 27% of the total world energy consumption. Conventional TPP produce more than 700,000 tonnes of fly ash per year. Annually fly ash production only in Russia, according to various estimates, is 27–35 million tons. Various apparatus are used to clean the gases from the fly ash. Required collection efficiency of purification units must to be 99.5–99.7% and higher. Wet scrubbers makes ash recycling more difficult. It requires ash separation from the slurry and drying. One solution of gas cleaning problem is a electrocyclone. It provides gas purification efficiency up to 99.9% at initial ash concentration equal 50 g/m 3 and higher. An electrocyclone allows to obtain a product in dry form. Re-entrainment is return of captured material to clean gas stream. Re-entrainment in the gas cleaning equipment is one of the negative effects. Re-entrainment reduces equipment efficiency at high gas velocities. The present study was carried out to determine the value of re-entrainment in the electrocyclone. The object of study was the electrocyclone of ‘pipe in pipe’ type. Aluminosilicate fly ash from thermal power plant (TPP) was the test material. Study was carried out in dry and wet modes. Re-entrainment was observed in dry operation mode. No re-entrainment was observed in wet operation mode. The value of re-entrainment was calculated. It decreases collection efficiency from 99.9% to 60%. Re-entrainment depends on aerosol velocity (range 14–27 m/s) and the aerosol concentration (range 2–30 g/m 3 ). It is shown, what re-entrainment can be eliminated by water irrigation of collecting electrodes.