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A novel hybrid supplying system with DG based on the concept of energy pool is proposed in the paper. The hybrid supplying system consists of two layers: the dc layer collects unconstant power provided by distributed energy sources and forms an energy pool with some energy storage units; and the ac layer connects to the common power grid and exchanges energy as needed between the local supplying system...
The grid-connected issue is one of the most importance problem in the photovoltaic generation field. The filter used to connect the grid can be L, CL, LC or LCL four forms according to the different conditions. LCL filter, which can reduce the required filtered inductance and save the cost, is adopted to connect the grid in this paper. This paper firstly introduces a whole scheme of LCL filter design,...
The modeling method based on fuzzy inference (MMFI) is applied to ordinary nonlinear system in this paper which interpolation function is once determined, the object model shall be determined. Because different systems apply different interpolation functions, the reestablishment of the system model is necessary, if adopting interpolation function to create the system model. A class of parameters adjustable...
A new-style dynamoelectric device of unipolar induction is putted forward in this paper, which possesses many virtues such as small-bulk, lightweight, unpolluted and unipolar induction as well as simple, it can be used in transport facilities such as the bicycle etc., so as to supply lighting because of its convenient assembly. It is mainly composed of a permanent magnet, soft magnet and an inductive...
The generator/motor is one of three key elements in a flywheel energy storage (FES) system, The objective of the flywheel system is the store and supply power in spacecraft applications and vehicles. Where a high speed brushless DC motor is chose. In high speed motor, the iron loss increases along with the alternant frequency of the magnetic field in the iron. A calculation model of iron losses of...
The article deals with the problems of decreasing peaks and possible ways of equalizing curve of power demand in big cities based on the example of Ekaterinburg, Russia's No.3 big city.
To research the thermal parameters of solar heat pump at Tibet, this paper presents two heating systems which apply different solar collectors. The factors such as time-varying, solar collectors and different weather conditions are considered in this paper. Furthermore, according to the different operating conditions, calculation and analysis about temperatures of the systems are carried out. The...
This paper, the combustion characteristics at different heating rates of biomass were investigated via thermogrovimetry. TG experiment has been done in air atmosphere at different heating rates, viz. 20, 30, 40, 50 and 60 K min-1. The results showed that biomass burning in the air atmosphere at 100 ~ 150 square, 290 ~ 340 square, 350 ~ 550 square, there are three major weight-loss processes: dehydrating...
The paper presents an ontology model, developed with knowledge based editor, Protigi 3.3.1, for wind turbines' condition monitoring. The ontology model proposed by the authors, describes the wind turbine components, developed a knowledge base, and can be used as the basis of fault detection and diagnosis system to reduce cost per kWh of generation. It Includes sensing specifications, according to...
Sites and capacities of substation is one of the key issues for distribution system planning, with the influences of load reliability and network structure. Now days, more influences of substation on society and environment have been concerned by people, and substation planning must be carried out according to the corresponding factors, besides economic cost. This paper presents a new approach for...
The fact of a dominant resonance frequency existed in the transient process of short-circuit fault is discovered by analyzing transient characteristics of single-phase earthed fault. At this frequency, the magnitude of zero modal current in faulty feeder is much larger than that in healthy feeder, and their phase is approximately opposite. Dominant transient frequency(DTF) zero modal current in faulty...
Anti-islanding protection of power disturbing method for a two-stage photovoltaic grid-connected inverter is designed in this paper. There is little coupling between the input and output power of the inverter as the dc-dc and dc-ac conversion is independent from each other. Step change of voltage across the dc-link filtering capacitor results in a change of stored energy of the capacitor and consequent...
A coherent groups recognition method using fuzzy clustering method based on A-K networks is proposed. Firstly, a fuzzy similarity matrix is formed by applying maximum-minimum algorithm. Then the A-K networks are trained with each row of the fuzzy similarity matrix as inputs. The nerves of output layer which win ultimately represent different dynamic styles. Finally, it is tested on the EPRI-36 bus...
Based on the stator flux linkage oriented control theory of doubly fed induction generator (DFIG), the control system of the megawatt level variable speed constant frequency (VSCF) wind turbine generator system, which adopts back-to-back PWM converters, is proposed. The Dual-PWM converter is divided into two parts: grid side converter and rotor side converter. The grid side converter adopts the voltage...
The doubly excited brushless reluctance machine (DEBRM) is a new type of reluctance machine and is attractive for converter-fed variable speed drive applications and variable-speed constant-frequency generating systems. The DEBRM system features not only simplicity, robustness and reliability of the reluctance or cage-rotor inductance machines, but a much smaller power electronic converter, compared...
In this paper, familiar means of energy storage are compared with respect to both performance and cost, on the basis of which some general rules are discussed on how to select proper energy storage means. Based on integrative analysis of capacity-fluctuation's impact on system and customers, some technical requirements of energy storage capacity configuration are determined. Proper capacity proportion...
Coal mines distribution network is a non-solid earthed power transmission system, which are routinely subjected to single phase to ground fault, when fault appears, fault current is weak, which is very difficult to find the fault point. Because of the wave speed is not sure, the existing methods of fault location based on traveling waves are not perfect. In this paper, a new fault location method...
Short term wind forecasting is a very important work to the operation of wind farms and power systems. In this paper, ARCH (Autoregressive Conditional Heteroscedasticity) effects of wind data series are analyzed with Eviews software. Firstly, an ARMA (Autoregressive Moving Average) model of wind speed time series is built. Secondly, ARCH (Autoregressive Conditional Heteroscedasticity) effect of the...
This paper introduces the configuration and components of a solar absorber receiver in the parabolic trough solar power system. The failure or degradation of the receiver, mainly including glass-to-metal sealing failure, loss of vacuum and degradation of solar selective coating, is the single largest cost factor for current and future solar power plant. The article elaborates the principle of glass-to-metal...
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