The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Static var compensator (SVC) and thyristor controlled series compensator (TCSC) are used to improve Transient Voltage Stability of the asynchronous wind farm in this paper. The related structure model of the wind farm power system is built in Matlab / Simulink. The contributions of SVC and TCSC to Transient Voltage Stability of the asynchronous wind farm and power grid are verified by the simulation...
As the operation performances and reliability of semiconductor devices are tightly related to its junction temperature, the research on the junction temperature prediction and thermal modeling do a significant meaning to extend services lifetime and improve application reliability of the IGBT modules. The physical structure and conception, RC thermal compact network component model, test principle...
In this paper, a measurement of the super transient reactance considering the stator winding resistor is put forward, and the steady shortcut current and voltage of two phases in the stator are analyzed as well as relative formula. Based on the data collection system, the super transient reactance in the 3-phase synchronous generator can be obtained. Then correspondent experiment is conducted to testify...
Electrostatic discharge is a well-known electromagnetic interference. Its transient field can affect operation of electronic equipment. In the paper, the transient electromagnetic field of indirect electrostatic discharge through vertical coupling plane is numerically simulated by using the FDTD method. An expression of pulse function is used as the electrostatic discharge current. Configuration with...
A concept named 'steady process in transient condition' is proposed for transmission line based on the transient expression of electromagnetic traveling wave. Considering the impact of distributed parameters and the characteristics of electro-magnetic wave, the transmission line model is built. Wave impedance factor is defined with line voltage fluctuation. The voltage equation is derived and the...
A transient flow model for heated oil transportation pipeline is built with application of continuity, momentum and energy conservation equations of pipe flow. The transient friction term of the model incorporates both of the steady and unsteady friction and the Brunone-Vitkovsky model is selected to compute unsteady flow friction in pipeline. The method of characteristic, finite-difference scheme...
Up to now, most studies and evaluation about CCHP (combined cooling, heating and power) pollutant emissions is at steady state and full load of power output, the transient pollutant emissions during micro-turbine startup are neglected without persuasive reasons. In fact, at partial loads and transient processes the pollutant emission characteristics can be very different from rated conditions. It...
A new fault isolation and restoration technique for distribution automation, which employs local Ethernet network, is presented. It can isolate all short circuit faults in the loop within 300ms and restore the supply of healthy sections in less than 1.2 seconds. A reliable fault location method for isolating the single phase to ground fault in the non-effectively earthed network, which makes use of...
This paper presents a novel digital control algorithm to enhance the dynamic performance of a dc-dc converter for non-high-frequency arc (NHFA) plasma cutting power supply. Using the principle of capacitor charge balance, the proposed algorithm predicts the optimal transient for a dc-dc converter during a load change. A 16kW experimental prototype of the NHFA plasma cutting power supply is designed...
Firstly the paper introduces the characteristics of Electrical Fast Transient (EFT) and analyzes some maloperation cases of the current differential protection for transformer. Based on the characteristic of electrical fast transient burst, an anti-interference criterion is presented. Analysis of field record data and a large number of simulation show that the presented criterion can effectively improve...
Present single-phase reclosure in ultra-high-voltage (UHV) and extra-high-voltage (EHV) transmission lines normally using a dead reclosing time may aggravate severe damage to the system and equipments, for unsuccessful reclosure in permanent fault or insufficient transient fault. Thus, it is important to study on the single-phase permanent detection technique aiming to lower unsuccessful reclosing...
With the wide use of Extra High Voltage Gas Insulated Substation (GIS), Very Fast Transient Over-voltage (VFTO) generated by switching operations threatens the insulation of some equipments even the security of the whole power system. The transformer is the main casualty of VFTO. For a 800kV GIS, the model has been built up and the parameters have been selected in this paper. VFTO magnitudes as well...
This paper uses the grid-connected photovoltaic (PV) power plant electromechanical transient simulation model on FASTEST (Fast Analysis of Stability using the Extended equal area criterion and Simulation Technologies) to do the simulation of PV power plant integrated to the grid. The simulation includes the largest installed capacity of PV power plant and the response of PV power plant when solar...
This paper analyses the advantages and disadvantages of fault line detection methods for neutral un-effectual grounded system at home and abroad, proposes a novel fault line detection algorithm based on morphological operator and rough set theory. Using rough set theory to amplify weak signal and morphological operator to identify the polarity of the fault zero sequence current's first wave, it can...
Proposed a morphological filter and wavelet transform combined method for super high-speed fault phase selection. In this method, the amount of the fault phase transformation by Karen Bell fault components into modules. And then strike the wavelet transform modulus maxima modulus, and finally according to characteristics of modulus maximum modulus construct a new component fault phase. The selector...
This paper presents some electromagnetic transient results on a Transmission Line a little greater than the Half Wavelength (HWL+). It was used an 800 kV non-conventional line with 2600 km and towers with three bundles of eight conductors each and a natural power of 4.8 GW. The studies conducted consist of line energization, load rejection, line tripping and reclosing. The transients arisen from the...
This study proposes an islanding detection method for use of grid-connected inverter of distributed renewable generation system. The proposed method is based on two indices: the rate of change of voltage (ROCOV) and the rate of change of frequency (ROCOF). When an inverter is grid-connected, the ROCOV and ROCOF are lower than the threshold values. In contrast, as an islanding occurs, the ROCOV or...
A numerical simulation was carried out to investigate fuel injection rate and cavitation phenomenon on different oil pump speed inside the injector. Simulation starts in steady flow at minimum needle lift, and then continues computing whole fuel injection process by unsteady method. Mixture and cavitation model were applied in description of two-phase flow in Fluent and self-made programs are added...
The neutral point in medium voltage distribution system is mainly non-effectively earthed in China. The important characteristics of this system are the fault-phase voltage decreasing and the un-fault-phase voltage increasing when SLG (Single-Line-to-Ground) fault happened. Due to the existing of line capacitance, the transient progress of un-fault-phase voltage increasing can be regard as a charge...
This paper analyzes the transition characteristic of the doubly-fed induction generator (DFIG) during the grid fault, and the approximate short current calculation which is based on the fifth-order DFIG model is also introduced to support the analysis. A novel method which is easier and more accurate than the past ones is proposed to verify the low voltage ride through (LVRT) characteristic of the...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.