Conventional Power Generation Systems Research Articles

Load Frequency Control of Multi-Region Interconnected Power Systems with Wind Power and Electric Vehicles Based on Sliding Mode Control

In recent years, wind power systems have been used extensively, which not only improve the efficiency of current conventional power generation systems, but also can save traditional fossil fuel resources. However, considering the instability of wind power, after being grid connected, it can easily cause an impact on the stability of the grid operation. Considering the above problems, this paper considers to make full use of the energy storage part of electric vehicles (EVs) to increase the stability of grid operation. Based on the mathematical model, this paper studies the load frequency control (LFC) problem of a multi-region interconnected power system with wind power and EVs. First, since the system states are difficult to be monitored, a state observer is designed to estimate the state. Based on this, the integral sliding mode controller (SMC) is designed to realize the LFC of the interconnected power system. Meanwhile, to obtain better control performance, this paper further analyzes and optimizes the controller parameters based on Lyapunov stability theory. At last, simulations are carried out for the power systems with two regions in Simulink. The results show that the designed controllers are effective to compensate the load demand disturbances. In addition, it is demonstrated that the battery storage of EVs can play the role of peak-shaving and valley-filling in LFC.

Conceptual Design of an Aviation Propulsion System Using Hydrogen Fuel Cell and Superconducting Motor

This paper deals with the possibility of applying superconducting motors and hydrogen fuel cells to electric aviation propulsion systems (APS) for the development of next-generation APS. Instead of the conventional fossil fuel-based power generation system, the APS using hydrogen fuel cells and superconducting motors was conceptually designed. The proposed APS consists of a superconducting motor, a hydrogen fuel cell, a liquid hydrogen tank, and a battery. For specific power comparison, the proposed APS capacity was the same as that of a commercial APS, and the capacity and weight of the hydrogen fuel cell and battery were calculated. The 5 MW superconducting motor was designed and analyzed focusing on magnetic field distribution, thermal load, mechanical stress, efficiency, weight, and specific power. As a result, the proposed APS is expected to reach the level of performance applicable to aircraft in the near future, given the recent development trend of battery and liquid hydrogen technology. These results are expected help in a future-oriented APS design.

Design of an Efficient System to Harvest Energy from Structural Load

Human has needed and used energy at an increased rate for their various uses. As a result, huge amount of energy is exhausted and lost. Our objective is to harvest energy from the vehicle with or without load using mechanical gear system and to increase the efficiency level of the energy. The gear system will make the generator rotate, thus producing energy. This work is a real-time work as lot of vehicles moving daily will cross over the setup, generating efficient amount of electrical energy. It is an eco-friendly system as it doesn’t harms anything. It is a conventional power generation system when compared to existing systems. The work deals with the design of the model in real-time of the energy harvester using gear arrangements and increase in efficiency level of energy. The most challenging part in this assignment is the material that is to be used as top plate assembly, such that it can absorb heavy loads like buses, trucks with water tanks etc. Below the plate there are springs in which deformation will take place. The gear assembly is connected to the bottom of the spring through its teeth. When the spring gets deformed due to load, the gear assembly will be rotated which in turn will rotate the generator as it is coupled to the gear assembly. So energy will be produced. To increase its efficiency, gear assembly consisting of different sizes of gears, is used to increase the rotation of the generator which will produce more electrical energy. Generally, the output will be AC (alternating current), so AC to DC (direct current) converter is used. Amplifiers can also be used to make the energy more efficient and store it in battery for further application.

Impact of Renewable Energy Sources into Multi Area Multi-Source Load Frequency Control of Interrelated Power System

There is an increasing concentration in the influences of nonconventional power sources on power system process and management, as the application of these sources upsurges worldwide. Renewable energy technologies are one of the best technologies for generating electrical power with zero fuel cost, a clean environment, and are available almost throughout the year. Some of the widespread renewable energy sources are tidal energy, geothermal energy, wind energy, and solar energy. Among many renewable energy sources, wind and solar energy sources are more popular because they are easy to install and operate. Due to their high flexibility, wind and solar power generation units are easily integrated with conventional power generation systems. Traditional generating units primarily use synchronous generators that enable them to ensure the process during significant transient errors. If massive wind generation is faltered due to error, it may harm the power system’s operation and lead to the load frequency control issue. This work proposes binary moth flame optimizer (MFO) variants to mitigate the frequency constraint issue. Two different binary variants are implemented for improving the performance of MFO for discrete optimization problems. The proposed model was evaluated and compared with existing algorithms in terms of standard testing benchmarks and showed improved results in terms of average and standard deviation.

A Novel Lagrangian Multiplier Update Algorithm for Short-Term Hydro-Thermal Coordination

The backbone of a conventional electrical power generation system relies on hydro-thermal coordination. Due to its intrinsic complex, large-scale and constrained nature, the feasibility of a direct approach is reduced. With this limitation in mind, decomposition methods, particularly Lagrangian relaxation, constitutes a consolidated choice to “simplify” the problem. Thus, translating a relaxed problem approach indirectly leads to solutions of the primal problem. In turn, the dual problem is solved iteratively, and Lagrange multipliers are updated between each iteration using subgradient methods. However, this class of methods presents a set of sensitive aspects that often require time-consuming tuning tasks or to rely on the dispatchers’ own expertise and experience. Hence, to tackle these shortcomings, a novel Lagrangian multiplier update adaptative algorithm is proposed, with the aim of automatically adjust the step-size used to update Lagrange multipliers, therefore avoiding the need to pre-select a set of parameters. A results comparison is made against two traditionally employed step-size update heuristics, using a real hydrothermal scenario derived from the Portuguese power system. The proposed adaptive algorithm managed to obtain improved performances in terms of the dual problem, thereby reducing the duality gap with the optimal primal problem.

Trinary Hybrid Cascaded H-Bridge Multilevel Inverter-Based Grid-Connected Solar Power Transfer System Supporting Critical Load

Higher power rating solar photovoltaic systems are emerging in the power system owing to the reduction in the cost of photovoltaic arrays and environmental concerns of the conventional power generation systems. Multilevel inverters are reported at high power levels due to reduced switching frequency and increased efficiency. Cascaded H-bridge (CHB) multilevel inverters have been reported in the literature due to its redundant structure compared to other multilevel topologies. When CHBs with dc sources are in the ratio of 1:3, it is named as a trinary hybrid multilevel inverter, and it generates a maximum number of equal output voltage levels. In this article, a trinary CHB multilevel inverter-based grid-connected solar power transfer system using modified second-order generalized integral control is proposed. A two-stage solar PV system consists of a single-input-multiple-output single-ended primary inductance converter and two CHB structures per phase used to verify the proposed system. A modified second-order generalized integral control is presented for active power control and grid synchronization. The controller is designed to eliminate dc-offset from the sensed load currents and to ensure balanced, sinusoidal, and unity power factor grid currents. Moreover, the shunt-connected system mitigates the reactive power and harmonic demands of the local load, thus maintaining the grid current power quality within the standard prescribed by IEEE-519. The performance of the proposed system is validated with an experimental prototype, and the test results validate the theoretical claims.

Environmental aspects of fuel cells: A review

Fossil fuels represent the primary energy supply utilized worldwide. Despite this, fossil fuels are both limited resources and have severe environmental impacts that result in climate change and several health issues. Fuel cells (FCs) are efficient energy conversion devices, which can be used for energy conversion and storage. Although different types of FCs exhibit promising features for future usage, they also have some environmental aspects that ought to be addressed. This review summarizes the different types of FCs, including the advantages and disadvantages of each. The different environmental aspects of the common types of FCs are then comprehensively discussed. This review also compares FCs to conventional power generation systems to illustrate their relative environmental benefits.Although FCs are considered more environmental-friendly compared to conventional energy conversion systems, there are still evident operational and environmental setbacks among different FC types. These setbacks, however, must be compared in context of the intended application, fuel type, and all other involved factors in order to have a clear and fair comparison. FCs are considered environmentally friendly and more efficient. However, this is usually only when considering the operational phase or the operational perspective. The main challenge facing FCs still remains fuel sourcing, like, for example, in the case of obtaining hydrogen for hydrogen FCs, where hydrogen production causes environmental impacts. The same applies for electrode materials, where, in many cases, either a noble metal such as platinum, or other precious metals, or costly material. With this consideration, a life cycle assessment (LCA) is a useful tool that considers all of the manufacturing, fuel sourcing, and operational phases. Although using FCs shows evident environmental improvements compared to conventional energy sources, the LCA of FCs compared to that of conventional power sources shows a similar performance. This is mainly due to the EIs associated with fuel sourcing and material acquisition, either for precious metals used for low-temperature FCs, or thermally and chemically stable materials used for medium- and high-temperature FCs. Both of these also contribute largely to the cost of FCs. Developments in both areas will undoubtedly help to make FCs both more environmental-friendly and cost-efficient.

Optimal operation of water-energy microgrids; a mixed integer linear programming formulation

Increasing energy efficiency in water distribution systems is one of the most important aspects of a sustainable water infrastructure. Additionally, providing this energy from renewable sources is an essential step towards a cleaner production in energy infrastructures. Therefore in this paper, an optimization model is developed to minimize the energy consumption of a water-energy microgrid system. A day-ahead economic dispatch model is developed to minimize the daily cost of energy in the water-energy microgrid. The energy consumption of water system is minimized using tank’s and pump’s scheduling and operation, hydraulic factors, and daily demand. Particularly, the electricity consumption of the pump is minimized by adjusting its head gain and flow rate via a variable speed. The energy unit is composed of an aggregated conventional power generation, solar photovoltaic, wind generation, and battery energy storage system. To offer a global optimum for the proposed non-linear programming formulation, bivariate piecewise linear approximation is used to linearize the pump’s power consumption and gain, and conservation of energy-mass. In addition, univariate piecewise linear approximation is used to linearize the energy consumption function of conventional power generation systems. The optimization results of the mixed integer linear programming and mixed integer non-linear programming formulations for the studied water-energy microgrid system are compared and discussed. These models are developed to concurrently minimize the electricity consumption of a micro water-energy distribution network in two scenarios of (1) standalone water distribution system operation and (2) an integrated islanded micro water-energy system with electrical loads.

Designing an optimized configuration for a hybrid PV/Diesel/Battery Energy System based on metaheuristics: A case study on Gobi Desert

Among different renewable energies, the sun as an endless source of energy has been the focus of many researchers worldwide. The use of solar radiation energy in conventional power generation systems can play an important role in reducing fuel consumption and environmental pollution. The importance of this energy has been increased when we need to supply the load demand, especially in desert-like places. The main objective of this research is to propose a new optimal hybrid solar/diesel/battery system to cover the demand load of a rural part in the Gobi Desert in China. The main objectives for optimization are the loss of load probability, CO2 emissions value, and the annualized cost of the system. Here, the ε-constraint method is adopted to simplify the multi-objective problem into a single objective problem. The optimization of the problem is performed by a developed version of the elephant herd optimization algorithm and the system sensitivity analysis has been analyzed on the parameters. Simulation results show that the proposed method can provide a reliable supplement for the load demand such that the PV penetration has a prominent impact by 97.9% of the costs. The results also present that the emitted CO2 gas by the proposed cEHO algorithm by 1735 kg/year is the minimum value compared with the PSO-based optimal system and HOMER software results. The initial capital cost of the system is also achieved 48,680 $ that specifies less value than the net present cost.

Integration Schemes for Hybrid Generation Systems

The progress in renewable sources,the wind energy has given rise to augmented attention on more trustworthy and useful electrical generator systems. Because of the reason that sunlight and wind energy is alternatingin nature and has great success in power generation over conventional sources.However due to irregular in nature andhigher dissemination of renewable sources, in present day Power generation plants many technical problemsparticularly when used independentlyconnected to grids or standalone systems without appropriate energy storage devices. To make the system more reliable the integration the two renewable resources into an optimum combination, cansolve the impact of the inconsistent nature of solar and wind resources andalsomake the system efficient to run. The paper gives you an idea aboutproblems and its related best solutions for integrating hybrid solar, wind and conventional Power generation systems both a grid connected and standalone system.Voltage and frequency fluctuations generate harmonics which are significant reasons of power quality and have very high impact on power generation. By proper design and advances fast response controllers and goodOptimization techniques resolve the problem to large extent. The paper also provides review on optimal sizing design, power switching devices and its control. The paper presents types of integrated schemes available in Hybrid systems for both grid-connected and standalone Solar PV and Wind Systems.

The optimal sizing and performance assessment of a hybrid renewable energy system for a mini-gird in an exclave territory

Single reliance on diesel energy has put a wide range of problems on off-grid power systems operating in remote areas of Oman. The operation of off-grid of an exclave territory of Oman is more complex, costly, and unsustainable. Hybrid Renewable Energy Systems has strongly emerged as a viable alternative to the current diesel generation plants. Proper component selection, optimum grid sizing, and performance evaluation in the economic, environmental, and reliability paradigms are crucial steps in their design process to optimize the intended benefits. This paper uses HOMER software to optimally retrofit a mini-grid power system in an excalved tiny territory of Oman. Medha region is an exclave territory of Oman and enclaved by the United Arab Emirates. Diesel-fueled generators supply the mini-grid of this tiny territory of Oman. Medha Wilyat’s peak demand is 8 MW. This paper investigates the potential utilization of renewable energy to offset diesel fuel consumption, in which the price is persistently volatile and increasing. This study discusses the possibility of integrating renewable energy technologies like solar and wind with conventional power generation systems that use diesel and natural gas. Wind-natural gas-diesel-based hybrid system was found to be the most viable system compared to other combinations in terms of the cost of electricity generation. Wind energy accounted for 52.4%; natural gas accounted for 47.2%, whereas diesel accounted for only 0.44%. Another finding was that operating cost for the wind-natural gas-diesel combination was among the lowest of all combinations since renewable energy integration was highest among all combinations. This study clearly shows that the integration of renewable energy to displace diesel power generation can be cost-effective for off-grids and environmentally friendly through a substantial reduction of greenhouse gas emissions. Cost savings from displacing diesel from mini-grids are most likely to increase in the coming years.

Heat energy harvesting by utilizing waste heat with small temperature differences between heat source and sink

In this review work, energy harvesting methods for waste heat with small temperature differences between heat source and sink are discussed. At present, many methods are tried and employed to utilize this type of waste heat. A typical example is found in a conventional power generation system. By utilizing this type of waste heat, additional energy can be produced in regular power generation systems. Up to this point, two energy harvesting methods have been introduced and applied for the use with this type of waste heat. One is a method using an organic Rankine cycle (ORC) while the other is a method using a thermoelectric generation (TEG). An ORC is a Rankine cycle that can be applied to this type of waste heat using organic fluids such as refrigerants as working fluids instead of water used in a typical Ranking cycle. On the other hand, a TEG utilizes Peltier, Seebeck, and Thomson effects caused by the temperature difference between the heat source and sink for energy harvesting. In this work, various aspects associated with the use ORC and TEG for waste heat harvesting with small temperature differences between the heat source and sink.

Conceptual design and optimization of power generation system for lead-based reactor

The lead-based reactor is one of the key nuclear energy systems for Generation-IV (Gen-IV) and Accelerator Driven Subcritical Systems (ADS). The Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences (INEST, CAS) has taken significant initiative for the design and development of the China Lead-based Reactor (CLEAR) series since 2011. The conventional power generation system has low performance and optimization of main parameter is a challenge when power generation system is connected with lead-based reactor. A new/modified conceptual design of an efficient power generation system with two reheaters has been proposed on the basis of a 400 MWth (thermal power) lead-based reactor with high performance. The analysis results show that the thermal efficiency was influenced by number of reheaters (with bleed-off steam at different positions). The thermal efficiency of Schematic-III (with two reheaters) was 44.3% and higher than Schematic-I and II (one reheater with bleed-off steam from the supply line of the first regenerator and main supply line, respectively). However, key parameters of the power generation system have been optimized to increase the overall performance of Schematic-III. The optimized temperature of feed water at the inlet of the reactor was 360 °C with a flow rate of 237 kg·s−1 and the outlet temperature of the reactor was 558 °C. The efficiency and net power of the plant increased with the part load.

An Economic Examination of Solar Energy with Storage based Supply Options: Solar PV-Battery and CSP with Thermal-Storage

Renewable energy is being promoted amidst rising environmental concerns associated with fossil-fuel usage for power generation. The stock of such fuels is also limited and is fast depleting. Renewable energy sources such as solar photovoltaic (PV) systems present a clean alternative that has become cost-competitive with conventional thermal power generation systems. However, to counter the intermittent nature of solar power and ensure firm power supply, energy storage is essential. This paper presents a comparative analysis of power supply options based on two solar energy technologies - PV and concentrated solar power (CSP). Energy storage in the form of battery and thermal energy respectively has been included and different combinations of supply options, along with utility grid, have been analyzed in terms of the levelized cost of electricity (LCOE). The LCOE values for supplying a particular substation load in India have been compared and it was found that CSP with thermal energy storage emerged to be the economically viable option for supplying the load.

Performance analysis of an improved power generation system utilizing the cold energy of LNG and solar energy

Since the conventional power generation systems recovering the cold energy of LNG have relatively low energy utilization, an improved power generation system utilizing the cold energy of LNG and low-temperature solar energy is proposed and analyzed in this paper. The improved system integrates a precooler and solar collectors into a double-loop combined cycle system. A comparative analysis between the proposed system and conventional systems is done under the same optimization criteria. Then, the effects of system parameters including solar collecting temperature, heat source mass flow rate and double-loop condenser temperature on thermodynamic performance are also studied. The results show that the net power output and system thermal efficiency of the proposed system are 9.3% and 7.33% respectively higher than those of the conventional double-loop combined cycle system. Moreover, there is an optimal collecting temperature to maximize exergy efficiency and it is shown that a smaller heat source mass flow rate in a permissible range improves system performance. In addition, when the second-loop condenser temperature is around the phase change point of LNG, system performance declines slightly. The system performance thus has two optimal regions with the variation of the first and second-loop condenser temperature.

Development and sizing of a grid-connected solar PV power plant for Canaanland community

High costs of installation and maintenance as a result of storage units discourage the use of solar Photovoltaic system for power generation. To reduce these costs, Solar PV systems can be installed without storage units alongside conventional power generation systems. Such that the Solar systems cater for the daytime loads while the conventional generation system caters for loads at other times. This research paper explored the potential of installing Stand-Alone solar PV systems without storage to satisfy the daytime load demand of the Canaanland community. The load profile analysis of the Canaanland community was carried out from load consumption data and the solar power plants were designed based on this analysis. Simulation was carried out using the PV Syst 6.43 software and the result from the design was analyzed. The study revealed that the solar power plant will serve the daytime load of the community during the period of 10:30am-4:30pm daily satisfying the peak and base loads (5.16MW and 0.78MW) of the Canaanland community respectively.

A multi-objective risk-based robust optimization approach to energy management in smart residential buildings under combined demand and supply uncertainty

This paper formulates a risk-based robust decision making framework for a Smart Building (SB) energy management system under demand and supply uncertainty. The last aim of the resulting multi-objective mixed integer linear programming is to minimize the total day-ahead cost of the system, in which the objective functions are the total cost of heat and power co-generation, and the total emissions cost. In this way, the first trade-off is made between economy and environmental impacts, while the second trade-off is occurred between solution robustness and model robustness. The results from a numerical example demonstrate the robustness and flexibility of the overall framework in dealing with Decision Makers (DMs) risk aversion level. In average, a more conservative decision maker faces a 75% increase in total cost, a 90% increase in electricity generation cost, and an increase of 8% in emissions cost compared with a more risk-seeker DM. Compared with the conventional power generation system, using the proposed Microgrid-based system brings about 92%, 93%, and 85% savings in total cost, cost of power-supply, and total emissions cost, respectively.

Energy Management and Control Strategy of Photovoltaic/Battery Hybrid Distributed Power Generation Systems With an Integrated Three-Port Power Converter

Photovoltaic (PV)/battery hybrid power units have attracted vast research interests in recent years. For the conventional distributed power generation systems with PV/battery hybrid power units, two independent power converters, including a unidirectional dc–dc converter and a bidirectional converter, are normally required. This paper proposes an energy management and control strategy for the PV/battery hybrid distributed power generation systems with only one integrated three-port power converter. As the integrated bidirectional converter shares power switches with the full-bridge dc–dc converter, the power density and the reliability of the system is enhanced. The corresponding energy management and control strategy are proposed to realize the power balance among three ports in different operating scenarios, which comprehensively takes both the maximum power point tracking (MPPT) benefit and the battery charging/discharging management into consideration. The simulations are conducted using the Matlab/Simulink software to verify the operation performance of the proposed PV/battery hybrid distributed power generation system with the corresponding control algorithms, where the MPPT control loop, the battery charging/discharging management loop are enabled accordingly in different operating scenarios.

Review: Enhancement of composite anode materials for low-temperature solid oxide fuels

Solid oxide fuel cell (SOFC) technology is attractive for its high-energy efficiency and expanded fuel flexibility. It is also more environmentally benign than conventional power generation systems. Recently, increasing attention has been paid to intermediate-to-low-temperature solid oxide fuel cells, which operating at 400–800 °C. Reducing its operating temperature can render SOFC more competitive with other types of fuel cells and portable energy storage system (EES) over a range of applications (eg: transportation, portable, stationary) and more conducive for commercialization. The high-performance composite anode requirements for low operating temperature (400–600 °C) demand microstructural and chemical stability, high electronic conductivity, and good electrochemical performance. The current high-temperature anode, Ni-YSZ (nickel-yttria stabilized zirconia) is generally reported with high interfacial resistance at reduced temperatures. This review highlights several potential composite anode materials (Ni-based and Ni-free) that have been developed for low-temperature SOFCs within the past 10 years. This literature survey shows that most of these anodes still exhibit relatively high polarization resistance. Focus is also given on reducing polarization resistance to maintain the cell power density. In literature, common approaches that have been adopted to enhance the performance of anodes are (i) selecting high-performance electrolyte, (ii) exploiting nanopowder properties, and (iii) adding noble metals as electrocatalysts.

A model predictive controller for improvement in power quality from a hybrid renewable energy system

Hybrid renewable energy systems are one among the key areas of research in the fields of sustainable energy in recent times. With the ever-increasing demand in need for energy, renewable sources of energy are much sought after as they are also environment friendly in nature when compared with their non-renewable energy system counterparts. A solar–wind turbine hybrid system is proposed in this research paper, and a generalized predictive controller has been implemented to improve the stability and power quality of the proposed hybrid system. Survey of related works indicates certain limitations in implementing renewable energy systems with respect to stability, reliability and flexibility in fuel which have been effectively addressed in this research article. A three-level inverter has been implemented to fine-tune the power factor which is a combined power factor in the proposed work. A FFT analysis on the power indicates a reduced total harmonic distortion in the proposed work and has been justified over the conventional MPPT-based power generation systems without a properly designed controlling method. The constraints in designing a hybrid system with respect to power quality act as input to the model predictive controller in the proposed work. The work could also be implemented in cascading two or more number of heterogeneous renewable power sources.