Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
This study proposes a new model of demand response management for a future smart\ngrid that consists of smart microgrids. The microgrids have energy storage units, responsive loads,\ncontrollable distributed generation units, and renewable energy resources. They can buy energy from\nthe utility company when the power generation in themselves cannot satisfy the load demand, and\nsell extra power generation to the utility company. The goal is to optimize the operation schedule of\nmicrogrids to minimize the microgrids� payments and the utility company�s operation cost. A parallel\ndistributed optimization algorithm based on games theory is developed to solve the optimization\nproblem, in which microgrids only need to send their aggregated purchasing/selling energy to the\nutility company, thus avoid infringing its privacy. Microgrids can update their operation schedule\nsimultaneously. A case study is implemented, and the simulation results show that the proposed\nmethod is effective and efficient....
In this paper, a gas-fired combined cycle power plant subjected to a pre-combustion CO2\ncapture method has been analysed under different design conditions and different heat integration\noptions. The power plant configuration includes the chemical looping reforming (CLR) of natural\ngas (NG), water gas shift (WGS) process, CO2 capture and compression, and a hydrogen fuelled\ncombined cycle to produce power. The process is denoted as a CLR-CC process. One of the main\nparameters that affects the performance of the process is the pressure for the CLR. The process is\nanalysed at different design pressures for the CLR, i.e., 5, 10, 15, 18, 25 and 30 bar. It is observed that\nthe net electrical efficiency increases with an increase in the design pressure in the CLR. Secondly,\nthe type of steam generated from the cooling of process streams also effects the net electrical efficiency\nof the process. Out of the five different cases including the base case presented in this study, it is\nobserved that the net electrical efficiency of CLR-CCs can be improved to 46.5% (lower heating value\nof NG basis) by producing high-pressure steam through heat recovery from the pre-combustion\nprocess streams and sending it to the Heat Recovery Steam Generator in the power plant...
In this study, in order to determine the reasonable accuracy of the compensation\ncapacitances satisfying the requirements on the output characteristics for a wireless power transfer\n(WPT) system, taking the series-series (SS) compensation structure as an example, the calculation\nformulas of the output characteristics, such as the power factor, output power, coil transfer efficiency,\nand capacitors� voltage stress, are given under the condition of incomplete compensation according\nto circuit theory. The influence of compensation capacitance errors on the output characteristics\nof the system is then analyzed. The Taylor expansions of the theoretical formulas are carried out\nto simplify the formulas. The influence degrees of compensation capacitance errors on the output\ncharacteristics are calculated according to the simplified formulas. The reasonable error ranges of\nthe compensation capacitances are then determined according to the requirements of the output\ncharacteristics of the system in the system design. Finally, the validity of the theoretical analysis\nand the simplified processing is verified through experiments. The proposed method has a certain\nguiding role for practical engineering design, especially in mass production....
The uncertainty of complex power systems increases the possibility of large blackouts due\nto the expectations of physical events, such as equipment failures, protection failures, control actions\nfailure, operator error, and cyber-attacks. Cascading outage is a sequence of dependent failures\nof individual components that successively weaken the power system. A procedure to identify\nand evaluate the initiating events and perform sequential cascading analysis is needed. In this\npaper, we propose a new screening methodology based on sequential contingency simulation of\ncascading outages, including probabilistic analysis and visualization model. Performance of a detail\ncascading analysis using practical power systems is suggested and discussed. The proposed screening\nmethodology will play a key role in identifying the uncontrolled successive loss of system elements....
This paper analyzes the power distribution and flow of an inductive power transfer (IPT)\nsystem with two coupled coils by using the Poynting vector. The system is modelled with a current\nsource flowing through the primary coil, and a uniformly loaded secondary first, then the Poynting\nvector at an arbitrary point is analyzed by calculating the magnetic and electric fields between and\naround of the two coils. Both analytical analysis and numerical analysis have been undertaken to show\nthe power distribution, and it has found that power distributes as a donut shape in three-dimensional\n(3D) space and concentrates along the edges in the proposed two-coil setup, instead of locating\ncoaxially along the center path. Furthermore, power flow across the mid-plane between the two coils\nis analyzed analytically by the surface integral of the Poynting vector, which is compared with the\ninput power from the primary and the output power to the secondary coil via coupled circuit theory.\nIt has shown that for a lossless IPT system, the power transferred across the mid-plane is equal to\nthe input and output power, which validates the Poynting vector approach. The proposed Poynting\nvector method provides an effective way to analyze the power distribution in the medium between\ntwo coupled coils, which cannot be achieved by traditional lumped circuit theories....
Loading....