Songjiang Power Supply Company

Shanghai, China

Songjiang Power Supply Company

Shanghai, China
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Liu Y.,Shanghai JiaoTong University | Liu Y.,Songjiang Power Supply Company | Tan S.,Shanghai JiaoTong University | Jiang C.,Shanghai JiaoTong University
IET Renewable Power Generation | Year: 2017

Coordination of hydropower with multiple renewable sources can effectively reduce the adverse effects of large-scale renewable energy integration in power systems. A yearly scheduling model was proposed for a hydro-photovoltaic (PV)-wind hybrid system, maximising its generation interval and considering firm generation limits. Firm generation ensures reliable monthly generation and reduces generation fluctuations. Because the probability distributions of wind power, water inflow and solar radiation are difficult to predict precisely, interval optimisation is employed to solve this problem by considering only the possible intervals of random variables. It reduces errors introduced by distribution assumptions, acquires possible generation intervals and reduces computation burden. To handle the scheduling model using intervals, a pessimistic preference ordering of interval numbers is employed. The proposed interval optimal scheduling model is illustrated and analysed for a realistic case study in Yunnan. © 2016 The Institution of Engineering and Technology.

Wang Y.-S.,China University of Petroleum - East China | Liu X.-M.,Songjiang Power Supply Company
Applied Mechanics and Materials | Year: 2013

It is a great significance for power supply reliability and smart grid to locate feeder fault quickly and accurately for distribution network. A new ground fault traveling-wave signal timefrequency analysis method is proposed, which decomposes the aerial mode component and zero mode component of fault current based on EMD to get multi-stage stable intrinsic mode function (IMF). The first IMF contains high frequency components which can reflect the mutation of signal. Hilbert-Huang transformation is done for the first IMF to get the instantaneous frequency of signal. And then check the moment of traveling wave arrival by the instantaneous frequency in the figure of IMF time-frequency. The fault distance is computed based on the time difference between the moments of wave arrived of aerial mode component and zero mode components. Simulation shows that this method is able to accurately give the distance of fault without the influence of the random fault condition such as fault transition resistance and the moment of fault. © (2013) Trans Tech Publications, Switzerland.

Chen W.,Donghua University | Shi J.,Donghua University | Zhu T.,Donghua University | Wang Q.,Songjiang Power Supply Company | And 3 more authors.
Electrochimica Acta | Year: 2015

Nitrogen and sulfur dual-doped mesoporous carbons (NSMCs) have been fabricated through a facile template-mediated pyrolyzing method using poly(ethyleneimine) (PEI) as sources of nitrogen (N) and carbon (C), ferrous sulfate(FeSO4 7H2O) as both precursor of sulfur (S) and activation reagent along with nanoscaled silica as sacrificial supports. The composition, morphology, and microstructure of the products are characterized using X-ray diffraction, scanning electron microscopy, nitrogen sorption analysis and X-ray photoelectron spectroscopy. It reveals that these NSMCs possess a BET surface area over 1064 m2 g-1and abundant mesoporous structure with pore size ranged from 4 to 20 nm. The atomic percentages of N and S functionalities are found to be 4.00 at.% N and 0.83 at.% S, indication of successful incorporation of both nitrogenand sulfur into carbon network. Benefiting from the aforementioned characteristics, these NSMCs show perfect supercapacitive performances, which have been demonstrated by cyclic voltammetry and constant-current charge/discharge cycling techniques. In 0.5 M H2SO4 electrolyte, the specific capacitance (SC) of the as-prepared NSMCs electrode can reach 280 F/g at a current density of 1 A/g. Even at a high rate capability of 100 A/g, the NSMCs electrode still shows the SC value as high as 232 F/g, retaining 83% of that at 1 A/g. Also, the electrode exhibits excellent charge/discharge cycling stability, and no measurable capacitance losses is observed even after 5000 cycles, making them potentially promising for high-performance energy storage devices. © 2015 Elsevier Ltd

Lu T.,Jiangsu University | Gao C.,Jiangsu University | Su W.,Songjiang Power Supply Company | Li Y.,Jiangsu University
Dianwang Jishu/Power System Technology | Year: 2014

Based on the idea of delicacy management for ordered power utilization and taking both fairness and reasonableness as the general guidelines and taking the demand in economy into account, a draft procedure for the preset scheme of peak averting is designed, and a concept of classification and grouping of the preset scheme of peak averting is put forward. Firstly, utilizing the method of comprehensive evaluation the priorities of all power consumers to participate the peak averting are determined and the ordering list for peak averting is formed; then according the ordering of peak averting and the capacity of avertable peak load the power customers are grouped; finally according to the sequential arrangement of power customer groups and taking the minimized social loss due to peak averting as the objective, the composition of power customer groups of various levels of peak averting load is optimized. Results of case study analysis show that above-mentioned drafting method for the preset scheme of peak averting can ensure that the power customers with smaller comprehensive evaluation values of peak averting priorities possess the priority right to participate the peak averting, thus both reasonableness and fairness of the preset scheme can be improved; the policy orientation such as industrial restructuring, energy saving and emission reduction of power customer and environment protection can be effectively reflected; meanwhile the excessive loss of partial large customers due to peak averting under traditional peak averting patterns can be prevented.

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.

Sun H.-P.,Shanghai JiaoTong University | Sun H.-P.,Songjiang Power Supply Company | Wang X.-T.,Shanghai JiaoTong University | Li X.-J.,Songjiang Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

Dynamic phasors have been introduced to the HVDC model to analyze its dynamic behavior. Dynamic phasor method shows high accuracy by representing the switch state of the valve with switching function. In the need of HVDC sub-synchronization oscillation analysis, we consider the influence of thyristor dead time and trigger control on the HVDC dynamic phasor model, and accordingly establish an improved HVDC dynamic phasor model based on the electromagnetic transient simulation platform. Based on the baseline system of HVDC, we make a simulation comparison between PSCAD custom model and the electro transient model, comparing the time response curve of state variables between AC and DC system with disturbance of different frequency. Consequently, we authenticate the applicability of the improved HVDC dynamic phasor model in different frequency ranges.

Liang R.,Chongqing University | Liang R.,China University of Mining and Technology | Jin Z.,Songjiang Power Supply Company | Liu J.-H.,China University of Mining and Technology
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

The transient characteristic propagates to both ends of line from fault point when a fault occurs in the distribution networks. A determined mathematical relationship is obtained between characteristic frequencies and distance from the fault point to observation point. The identification of wave front is unnecessary when using transient signal analysis based on characteristic frequencies, so that fault location error is avoided due to waveform distortion of time domain analysis. Some achievements and shortcomings are summarized from former papers, and a new single-ended fault location method is proposed and applied to medium distribution networks, which improves signal frequencies resolution and fault location accuracy. The proposed procedure builds an fault-waveform-inferred mother wavelets firstly, which enhances the adaptability of mother wavelets and resolution of characteristic frequencies; then characteristic frequencies are corrected by scalogram in time domain based on determined frequencies on the former step. Many simulations show the new method has good adaptability and high fault location accuracy.

Xiong W.,South China University of Technology | Xiong W.,Guangdong Power Grid Corporation | Wu P.,Songjiang Power Supply Company | Yu H.-B.,Songjiang Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

This paper proposes a state estimation method for the distribution network based on the load monitor system. The measured three-phase voltage and current, active and reactive power of distribution transformer are used as the measuring values in the state estimation algorithm. All the nodal voltage and angle of the feeder are seen as the condition variables. According to the data gathered from the load monitor system, all operational information of the distribution network and all bus voltage and power of feeder can be estimated by the Newton-based state estimation algorithm. From the calculation result, the operator can get more information from the network so as to make decisions. A real 10 kV distribution line equipped with the load monitor system is illustrated to validate the validity of the proposed method.

Liu X.,Songjiang Power Supply Company | Liu D.,Huazhong University of Science and Technology
Gaodianya Jishu/High Voltage Engineering | Year: 2016

Highly energetic electrons and reactive species, O and OH for example, in atmospheric non-equilibrium plasmas can react with pollutants and decompose them. Consequently, we numerically and experimentally studied the pulsed DC plasma jet propagation and OH production mechanism in atmospheric pressure. The simulation results reveal that the sheath formed near the dielectric tube inner surface separates the plasma channel from the tube surface. The strong electric field at the edge of dielectric field enhances the ionization in the air mixing layer, therefore, the streamer head changes into the ring shape when the streamer runs out of the tube. Penning ionization will dominate the ionization reactions and will increase the electric conductivity of plasma channel. For the plasma jet in the open air, the dissociation of H2O by electron, the recombination of H2O+ by electrons and dissociation of H2O by O(1D) are the main reactions to produce OH. The contribution of the dissociation of H2O by electron is more than that of the others.The addition of N2, O2 and air to the working gas will slightly increase the OH density, which is attributed to the increased electron density through Penning ionization. Although the addition of H2O increases the OH density inside tube dramatically, because of the air diffusion efficiently in the mixing layer, the limited increase of H2O mole fraction will only result in slightly increase of OH density outside the tube. The pulse number is found to be an efficient way to control the plasma activity. © 2016, High Voltage Engineering Editorial Department of CEPRI. All right reserved.

Zhang M.,Tongji University | Chen J.,Songjiang Power Supply Company
IEEE Transactions on Power Systems | Year: 2015

This paper presents a short-term power regulation mechanism for post-segmentation power distribution systems in the presence of severe fault or large disturbance. Firstly, load priority is introduced into system separation and centroids of load clusters are allocated at nodes with distributed sources, respecting power balance and network connectedness. Secondly, fast power flow calculation is performed on the primarily formed islands to resolve load interruption for operational feasibility of partitions from power quality perspective. Then the effect of distributed generation fluctuations on durable operation of subsystems with various optimization objectives is examined. The load response is instructed by the proposed cost-based pricing scheme contemplating consumers' willingness. In addition, the influence of network congestion and load controllability on results of economic scheduling is investigated. Numerical results from the PG&E-69 distribution system are used to show the effectiveness of the developed model in radial structure load clusters. Illustration on the IEEE 118-bus case further proves its robustness and practicability for other distribution systems applications. This property is also useful for transmission switching and micro-grid applications. © 2014 IEEE.

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