Modelling and optimization of combined heat and power system in microgrid based on renewable energy

Due to the short distance between the sources of production and consumption,microgrids(MGs)have received considerable attention because these systems involve fewer losses and waste less energy.And another advantage of MGs is that renewable energy sources can be widely used because these resources are not fully available and can provide a part of the required power.The purpose of this research is to model the MG considering the production sources of microturbines,gas turbines and internal combustion engines.Renewable energies such as wind turbines(WTs)and photovoltaic(PV)cells have been used to provide part of the required power and,because of the lack of access to renewable energy sources at all times,energy reserves such as batteries and fuel cells(FCs)have been considered.The power of the microturbine,gas turbine,internal combustion engine,FC and battery in this system is 162,150,90,100 and 225 kW,respectively.After modelling the studied system,optimization was done using the imperialist competitive algorithm to minimize production costs and provide maximum thermal and electrical loads.The maximum production power for PVs is equal to 0.6860 MWh and at this time this value for WTs is equal to 0.3812 MWh,in which case the excess electricity produced will be sold to the grid.

Thermo-economic analysis of the performance of the combined system with evacuated tube collectors

Using combined cooling,heat and power systems can be an appropriate substitute for preventing emissions of pollutants and excessive consumption of fossil fuels.Utilizing renewable energy in these systems as a source of power generation can be an appropriate substitute for fossil-fuel-based systems.Therefore,in this paper,cogeneration cooling,heat and power systems based on gas-fired internal combustion engines with a solar-thermal system with evacuated tube collectors have been modelled and thermo-economic analysis has been done to compare fossil-fuel-based systems.The required rate of heat to supply the hot water is 50 kW.In the studied system,the internal combustion engine produces electrical energy.Then,the solar-thermal system with evacuated tube collectors and the gas-burning generator provide the thermal energy required by the studied building and the primary stimulus of the absorption chiller for cooling.In this study,two different scenarios are conducted in states considering simultaneous production systems and regardless of this environmental and thermo-economic analysis system.The results showed that the efficiency of the studied system was 60% in summer and 56% in winter.

Investigation and optimization of solar collector and geothermal pump hybrid system for cogeneration of heat and power with exergy-economic approach

To use energy systems based on renewable sources,it is very important to consider backup and hybrid sources because renewable energies are not available all the time;therefore,in this system,a geothermal pump is used to preheat the fluid,then the heated fluid is sent to the vacuum tube collector to reach a higher temperature by absorbing solar-thermal energy,and after absorbing solar energy,it goes to the evaporator to produce superheated steam and finally the superheated fluid moves to the steam turbine to produce energy.After the simulation,thermodynamic analysis along with economic analysis has been done.In the base state,the energy efficiency and exergy of cogeneration were 0.566 and 0.156,respectively;the energy efficiency and electrical exergy were better than 0.057 and 0.065;and the overall output and immutable work values were 50 and 671.1 kW,respectively.

Parametric investigation of thermal behaviour of salt-gradient solar pool for climatic conditions

The use of solar energy is highly welcomed due to its availability everywhere.Among the types of solar energy technologies,the use of this type of energy to produce heat from different aspects is much more common,so in this research we have tried to examine different aspects of producing thermal energy from solar energy to supply the heat required by the pool.For this purpose,numerical modelling of the solar pool has been done by considering the heat-transfer characteristics and validation has been done to ensure the obtained results.In this paper,according to the physical realities facing solar systems in two scenarios,an analysis with shadow and without shadow has been done.One of the important results is that as the surface of the pool increases,the amount of heat absorption by the pool fluid will increase,but the effect of the shadow will decrease.

Improving the transition capability of the low-voltage wind turbine in the sub-synchronous state using a fuzzy controller

The main problem of wind turbines is associated with induction generators in their power supply during short circuits in the grid.In this research,a new method is presented for the uninterrupted operation of a wind turbine equipped with an induction generator fed on both sides of feeding during network errors.Wind farms equipped with a doubly-fed induction generator(DFIG)require two abilities to allow system operators to increase proficiency.These capabilities include fault ride-through and synchronization of output force fluctuations,especially when these generators generate significant electrical power.A MATLAB®software environment has been used to evaluate and improve the performance of these turbines.A fuzzy complement(FC)controller is used to improve the performance of the DFIG.The results demonstrate that this controller limits the operation of the turbine current and voltage in the short-circuit mode well.Regarding results obtained from comparing two different modes,it can be said that ripple is 4%in the FC mode,while this parameter is equal to 10%for the proportional-integral controller.