The effects of manganese dioxide (MnO 2 ) additives on the electrical characteristics of the Al-doped ZnO varistors are investigated. The leakage current densities of the samples decrease first and then increase again...
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The effects of manganese dioxide (MnO 2 ) additives on the electrical characteristics of the Al-doped ZnO varistors are investigated. The leakage current densities of the samples decrease first and then increase again with the increase of the amount of MnO 2 additives. Correspondingly, the nonlinear coefficients of the samples keep on increasing and then decrease. In addition, the donor densities increase monotonously with the amount of the doped MnO 2 increasing. The effects of MnO 2 additives on the electrical characteristics of the samples are different from the conclusion of previous literatures. The reasons of the distinct effects are supposed to be related with the donor and interface state densities of the samples.
With the rapid development of renewable energies,especially wind power,how to manage unexpected generation variations economically and reliably in dispatch has become crucial for modern power *** address this issue,th...
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ISBN:
(纸本)9781479900305
With the rapid development of renewable energies,especially wind power,how to manage unexpected generation variations economically and reliably in dispatch has become crucial for modern power *** address this issue,this paper presents an affine disturbance feedback robust dispatch(ADF-RD) methodology for powersystems with large scale wind power integration in the framework of adjustable robust optimization(ARO).This methodology divides the dispatching process into pre-dispatch and ***-dispatch decision immunizes against all possible realizations of uncertainties in a set,while re-dispatch which can be regarded as a feedback will be adaptively adjusted using an affine function with respect to the realized uncertainty in real *** ADF-RD methodology is applied to an hourly ahead dispatch(HAD) *** effectiveness and efficiency of the proposed ADF-RD methodology are demonstrated by numerical experiments carried on a five-bus system.
作者:
Ziyuan TENGMinfang HANFuel Cell and Energy Storage Center
Department of Energy and Power EngineeringState Key Laboratory of Control and Simulation of Power Systems and Generation EquipmentTsinghua UniversityBeijing 100084China
Energy is important for human survival and *** September 2020,the Chinese government announced that“China aims to have their CO_(2) emissions peak before 2030 and achieve carbon neutrality before 2060.”As China’s r...
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Energy is important for human survival and *** September 2020,the Chinese government announced that“China aims to have their CO_(2) emissions peak before 2030 and achieve carbon neutrality before 2060.”As China’s reformation and opening-up proceeds into its fifth decade,this new vision for its future is in line with that of the world’s major economies in terms of the need to reach net zero emissions globally by the mid-21stcentury[1].However,coal-fueled thermal powergeneration is currently dominant and accounts for more than 70%of the total amount of power generated in China,making it the world’s largest energy consumer and carbon *** on the country’s domestic resources,namely the abundance of coal and scarcity of oil and gas,it would be difficult to fundamentally change this coal-based energy structure in the short *** 2021,the global total energy sector was responsible for 36.3 Gt of CO_(2) emissions,including approximately 12 Gt from China,which thus accounts for one-third of the total global emissions[2].The demand for efficiency,energy savings,and emissions reduction in the powergeneration industry has become increasingly *** need has arisen to enhance ways in which to use coal cleanly and efficiently,reduce the consumption thereof,and replace coal with other forms of *** addition,carbon emissions need to be lowered by promoting the adoption of alternative powergeneration technologies that are more energy *** would require transformation away from coal power and the exploration of clean,efficient,flexible,and safe forms of energy as the main future development directions[3].
The analysis and simulation of power system are becoming more and more challenging as the complexity of system topology and components has been increased. In this paper, a hybrid parallel algorithm is proposed for the...
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The analysis and simulation of power system are becoming more and more challenging as the complexity of system topology and components has been increased. In this paper, a hybrid parallel algorithm is proposed for the real-time electromagnetic transient simulation (EMTS) of integrated powersystems containing multiphase machines. The proposed algorithm is com- posed of a novel network partition method called component level parallelization and the Multi-Area Thevenin Equivalent (MATE) method, which extends the flexibility of the network partition in parallel simulation. Moreover, several methods are developed to enhance the efficiency of the communication and computation. powersystems with up to 410 single-phase elec- trical nodes and 336 switches are simulated in a time step of 50 ~ts to validate the proposed algorithm.
Solid oxide fuel cell combined with heat and power(SOFC-CHP)system is a distributed powergeneration system with low pollution and high *** this paper,a 10 kW SOFC-CHP system model using syngas was built in Aspen *** ...
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Solid oxide fuel cell combined with heat and power(SOFC-CHP)system is a distributed powergeneration system with low pollution and high *** this paper,a 10 kW SOFC-CHP system model using syngas was built in Aspen *** operating parameters,such as steam to fuel ratio,stack temperature,reformer temperature,air flow rate,and air preheating temperature,were *** was conducted based on the simulation *** suggest that higher steam to fuel ratio is beneficial to the electrical efficiency,but it might decrease the gross system *** stack and reformer temperatures contribute to the electrical efficiency,and the optimal operating temperatures of stack and reformer when considering the stack degradation are 750℃and 700℃,*** air preheating temperature barely affects the electrical efficiency but affects the thermal efficiency and the gross system efficiency,the recommended value is around 600℃under the reference condition.
With the rapid growth of grid-connected wind power penetration level,it is necessary to study the impacts of wind power on power system *** small-signal stability of powersystems with large-scale wind power is explor...
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With the rapid growth of grid-connected wind power penetration level,it is necessary to study the impacts of wind power on power system *** small-signal stability of powersystems with large-scale wind power is explored using the eigenvalue analysis method.A prototype sample system,the two-synchronous-generator system with a wind farm,is proposed for theoretical ***,simplified models of wind turbines(WTs)and the corresponding equivalent models of wind farms are *** kinds of typical WT models,i.e.,squirrel cage induction generator,doubly-fed induction generator,and permanent magnet synchronous generator are ***,based on the simplified equivalent models,effects of large-scale wind farms on the electromechanical oscillation modes(EOMs)of synchronous systems are *** results indicate that wind farms of the three kinds of WTs have positive effects on ***,long transmission lines connecting wind farmto the systemmay produce negative effects on the small-signal stability of the system.
An understanding of electron relaxation properties in plasmas is of importance in the application of *** improved multi-term approximation of the Boltzmann equation is employed to study electron transport and relaxati...
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An understanding of electron relaxation properties in plasmas is of importance in the application of *** improved multi-term approximation of the Boltzmann equation is employed to study electron transport and relaxation properties in ***,inelastic and nonconservative collisions between electrons and neutral particles are *** expressions for the transport coefficients are obtained using the expansion coefficients and the collision operator *** solutions of the matrix equations for the expansion coefficients are also *** calculations of the Reid model are presented to demonstrate the accuracy of the improved multi-term *** is shown that the twoterm approximation is generally not accurate enough and the magnetic fields can reduce the anisotropy of the velocity distribution *** electron relaxation properties of Ar plasmas in magnetrons for various magnetic fields are *** is demonstrated that the energy parameters change more slowly than the momentum parameters.
The smart grid is attracting more and more attention in electrical engineering for its promising ***,huge challenges also exist in the implementations of the smart grid,such as high penetration of renewable energy res...
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The smart grid is attracting more and more attention in electrical engineering for its promising ***,huge challenges also exist in the implementations of the smart grid,such as high penetration of renewable energy resources,low carbon electricity and cyber-physical security,*** this paper,the latest progress of some research focuses and advance technologies in the development of smart grid is reviewed.
With the integration of renewable energy generations and other related changes,the smart grid,or the future electric power system,is confronted with new challenges and ***,it is a promising subject in electrical engin...
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With the integration of renewable energy generations and other related changes,the smart grid,or the future electric power system,is confronted with new challenges and ***,it is a promising subject in electrical engineering and much work has been done on *** paper reviews the recent advances on the technologies of smart grid and renewable energy integration,from the aspects of modeling,simulation,protection and control,stability,operation,and planning.
Battery energy storage systems(BESSs)can provide instantaneous support for frequency regulation(FR)because of their fast response ***,purely pursuing a better FR effect calls for continually rapid cycles of BESSs,whic...
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Battery energy storage systems(BESSs)can provide instantaneous support for frequency regulation(FR)because of their fast response ***,purely pursuing a better FR effect calls for continually rapid cycles of BESSs,which shortens their lifetime and deteriorates the operational *** coordinate the lifespan savings and the FR effect,this paper presents a control strategy for the FR of BESSs based on fuzzy logic and hierarchical *** fuzzy logic controller improves the effect of FR by adjusting the charging/discharging power of the BESS with a higher response speed and precision based on the area control error(ACE)signal and the change rate of ACE in a non-linear *** controllers effectively reduce the life loss by optimizing the depth of discharge,which ensures that the state of charge(SOC)of BESS is always in the optimal operating range,and the total FR cost is the lowest at this *** proposed method can achieve the optimal balance between ACE reduction and operational economy of *** effectiveness of the proposed strategy is verified in a two-area power system.
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