Du D.,Shanghai University |
Fei M.,Shanghai University |
Jia T.,Shanghai Electrical Group Co.
Transactions of the Institute of Measurement and Control | Year: 2013
Traditional networked control systems (NCSs) analysis and design have been based on the single closed-loop configuration. This paper studies the modelling and stability of multi-input multi-output (MIMO) networked control systems (NCSs) with multiple channels. Unlike the NCSs based on the single close-loop configuration, there exist data packet dropout, data packet out-of-order and network-induced delay in every channel, which make multi-channel MIMO NCSs more complex. In order to solve these network-related non-deterministic issues, a general switched system model with unknown switched sequence for multi-channel MIMO NCSs is first proposed, which can not only describe the MIMO NCSs where the controller communicates with sensors and actuators through distinct channels, but also can describe the NCSs based on the single closed-loop configuration. Based on Lyapunov stability theory combined with linear matrix inequalities (LMIs) techniques, a sufficient condition is then derived for multi-channel MIMO NCSs to be asymptotical stable in term of a set of bilinear matrix inequalities. Furthermore, the proposed results are easily extended to the uncertain MIMO NCSs. Finally, simulation results confirm the feasibility and effectiveness of the proposed method. © The Author(s) 2011.
Zhang M.,Tongji University |
Du Z.,Shanghai Electrical Group Company |
Lin X.,Tongji University |
Chen J.,Songjiang Power Supply Company
IEEE Transactions on Smart Grid | Year: 2015
The circulating current among the paralleled solid state transformers (SSTs) originated by the line parameter and mismatched output impedance comes into appearance in the islanded operation of the novel microgrid, the future renewable electric energy delivery and management system. In this regard, the aggregated control strategy of both virtual inductance and external inductance is proposed in this paper to suppress circulating current. The 'matching concept' regarding the parameter selection of virtual and external inductance is proposed to ensure the reliable operation of the system through constructing the complete small-signal model of SST. On the basis of aggregated control strategy and small-signal model, the adaptive virtual impedance control strategy is finally proposed by introducing the feedback of circulating current into the conventional virtual impedance control. The virtual impedance is adjusted adaptively according to the judgment algorithm to regulate the equivalent output impedance of SST. With this modification, the adjustment ability of virtual impedance control against sudden disturbance is improved and the circulating current is further reduced. The simulation results with nonlinear loading are presented to prove that the proposed control strategy, and the parameters determined by the matching concept substantially reduce the circulating current among SSTs and improve the accuracy of load sharing among SSTs. © 2010-2012 IEEE.
Liu J.,Fudan University |
Liu J.,Shanghai Electrical Group. Co. |
Liao W.,Shanghai Electrical Group. Co. |
Yu A.,Fudan University
Journal of Alloys and Compounds | Year: 2014
Fe-substituted lithium manganese phosphate (LiMn0.6Fe 0.4PO4/C), with a small particle size of 50 nm in diameter, is successfully prepared using a two-step sol-gel method. TEM analysis reveals that LiMn0.6Fe0.4PO4 particles are embedded in a porous carbon matrix, and carbon interconnected particles to form a secondary spherical-like morphology. The composite prepared in this study exhibits excellent electrochemical behavior in terms of specific capacities and rate cycling ability. Furthermore, the XPS spectral studies before and after aging test reflect the much lower surface reactivity of the LiMn 0.6Fe0.4PO4/C towards 1.5 M LiPF6 solutions. And the results also reveal the good stability of electrolyte/carbon interface. © 2013 Elsevier B.V. All rights reserved.
Zhang M.,Tongji University |
Lin X.,Tongji University |
Sun H.,Shanghai Electrical Group Co.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2014
In the future renewable electric energy delivery and management (FREEDM) microgrid, there will be circulating currents among solid state transformers (SSTs) due to the voltage differences and disproportionate output impedances, particularly in the islanding mode. The output voltage differences were fed back to reduce the errors of their phases and amplitudes in the droop controller. Meanwhile, the adjustable virtual impedance based on the fuzzy control is adopted to make the output impedance of SST match its rated power more exactly using instantaneous circulating current feedback. Simulations and analysis show that the control strategy can restrain the circulating currents well, and can improve the output voltage stability of SST. future renewable electric energy delivery and © 2014 Chin. Soc. for Elec. Eng.
Jia T.,East China University of Science and Technology |
Jia T.,Shanghai Electrical Group Co. |
Niu Y.,East China University of Science and Technology |
Zou Y.,East China University of Science and Technology
Information Sciences | Year: 2012
This paper investigates the problem of sliding mode control for stochastic system under the effect of packet dropout. In this work, a new sliding function dependent on the probability of packet dropout is constructed. By means of a Lyapunov function involved in sliding mode variable and system state, both the reachabiltiy and the stability are analyzed simultaneously, and the sufficient condition is derived via linear matrix inequalities. Finally, numerical simulation results are given. © 2012 Elsevier Inc. All rights reserved.
Qi L.,East China University of Science and Technology |
Qi L.,Shanghai Electrical Group Co. |
Shi H.,East China University of Science and Technology
Neurocomputing | Year: 2013
This paper focuses on the performance improvements of the permanent magnet synchronous motor (PMSM) using vector control. In this paper, a neural adaptive sliding mode control algorithm is proposed to accomplish the position tracking of the field-oriented control (FOC) for PMSM. The proposed algorithm is presented by combining the fast terminal sliding mode (FTSM) with the radial basis function (RBF). Hence, the algorithm can not only compensate the network approximation errors but also solve the problem that FTSM is greatly dependent on the parameters of the PMSM. Furthermore, it is conducted easily and improves the performance of the PMSM control system, such as the tracking accuracy, robustness and response speed, etc. The neural network parameters are updated according to the Lyapunov approach which is used to prove the stability of the closed-loop system. The experimental results testify that the proposed algorithm is feasible and effective and is capable of controlling the PMSM in the real applications. © 2013 Elsevier B.V.
Shi Y.,Shanghai Electrical Group Co.
Chinese Journal of Environmental Engineering | Year: 2016
The refractory organics in the chemical influent from a chemical industry park wastewater treatment plant were analyzed by GC-MS. An activated sludge respiration inhibition test was used to evaluate the microbial toxicity of the wastewater and its effect on the biochemical treatment system. Based on this information, a comparative study of the pre- and post-Fenton process was developed. The results show that the chemical influent contains a variety of refractory organics, which reveal microbial toxicity to the municipal sludge, whereas there were no obvious inhibitory effects to the sludge from the plant. When the COD was below 125 mg·L-1 in the biochemical effluent, the post-Fenton processed effluent COD was consistently lower than 60 mg·L-1, with a processing cost of under RMB 1.8 yuan·t-1 (sludge disposal cost was not included). The optimal conditions were a pH of 3.5, H2O2 dosage of 5 mmol·L-1, and Fe2+/H2O2 ratio of 1∶2. The number of recalcitrant components was reduced from 18 to 4. On the contrary, when the Fenton reagent was used for pretreatment, the B/C failed to reach 0.3 for several dosage combinations, illustrating an unsatisfactory improvement in biodegradability. Accordingly, the post-Fenton process is recommended as the proper method to apply to further transformation projects of the chemical industry park wastewater treatment plant. © 2016, Science Press. All right reserved.
Chen B.,East China University of Science and Technology |
Huang J.,Shanghai Electrical Group Co. |
Niu Y.,East China University of Science and Technology
International Journal of Systems Science | Year: 2012
This article considers the design of sliding mode control for stochastic Markovian jumping systems with actuator nonlinearities. In the design of integral sliding surfaces, a set of specified matrices are employed such that the connections among sliding surfaces corresponding to each mode are established. And then, a sliding mode controller depending on the transition rates is synthesised such that the reachability of the specified sliding surface can be ensured. Moreover, sufficient conditions for the stability of the sliding motions are derived. It is shown that the effect of Markovian switching can be coped with by the present sliding mode control method. Finally, the simulation results illustrating the proposed method are provided. © 2012 Copyright Taylor and Francis Group, LLC.
Wang J.,Zhejiang University |
Gao M.,Zhejiang University |
Wang D.,Zhejiang University |
Wang D.,Shanghai Electrical Group Co. |
And 4 more authors.
Journal of Power Sources | Year: 2015
Carbon coated Fe3O4 composite (Fe3O4@C) with bi-morphological architecture has been prepared via a chemical vapor deposition at 450 °C from Fe2O3 nanoparticles by using acetylene as the deposition vapor and carbon source. The Fe2O3 are fully reduced to Fe3O4 in a 10 min of deposition, showing submicron-sized octahedral Fe3O4 particles coated partially with a thin carbon layer mainly, and a few nano-sized Fe3O4 particles coated with carbon also. The deposition period of 20 min results in a further growth of the octahedral Fe3O4 particles and a reduction of the number of the nano-sized ones, correlating to a thick and fully coated carbon layer. Impurities of iron carbides generate in the composite with further prolonging the deposition to 30 min. The Fe3O4@C composite from 20 min of deposition shows superior electrochemical property to others. An initial reversible capacity of 570 mAh g-1 is obtained and the capacity fading is less than 5% after 60 cycles. The fabrication method is facile and time-saving. Such submicron size-predominated Fe3O4@C composite is hopefully not only favorable in alleviating the agglomeration of the iron oxide during cycling, but also helpful in getting high packing density of the anode material. © 2015 Elsevier B.V. All rights reserved.
SHANGHAI Electrical GROUP CO. | Date: 2012-04-03
Embossing machines; machines and equipments for metallurgy industry, namely, pig machines; elevators; foundry machines; steam turbines; hydraulic turbines; machine cutting tools; AC generators; centrifuges; shaft couplings for machines; food waste disposers; printing machines; hosiery looms; boilers and its accessory parts for power station; hydraulic engines and motors for machines; wind-powered electricity generators; lathe; power operated rammers; drill presses; punch presses; fans for cooling engines of motors; valves being machine parts; air compressors; hydraulic components for use with construction machinery, namely, pumps, motors and cylinders; shock absorbers for machines; mechanical seals; bearings as parts of machines. Navigation apparatus for vehicles in the nature of on-board computers; surveying instruments; electrical inductors; betatrons; electric cables; silicon wafers; integrated circuits; electromagnetic coils; electric converters; mutual inductors; electronic apparatus for the remote control of industrial operations; electric accumulators for vehicles. Freezers; air cooling apparatus; gas boilers; sewage processor, namely, dewatering machine for the treatment of sludge.