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Short-term load forecasting is important for the safety and economic operation of the wind power system. In order to forecast the power load more accurately, the Support Vector Machines (SVM) combined with the lifting wavelet transform is proposed in this paper. The lifting wavelet transform is used to find out the characteristics of original signal while the SVM is utilized to improve the precision...
Low voltage ride through (LVRT) problem has become an important issue in a power system with large capacity wind power. Many running wind farms should test their LVRT capabilities. Artificial short circuit test was carried out in a regional power grid in China to test the LVRT capabilities of several wind farms. Considering both security and effectiveness of the test, the reasonable selection of the...
High Voltage Direct Current (HVDC) Technology has been widely recognized advanced in power transmission. Classical HVDC has shown its advanced features in long distance bulk power delivery, submarine cable crossings, and asynchronous interconnections. Therefore, the new generation of technology, embedded HVDC, is further broadening the range of applications of HVDC transmission. The embedded HVDC...
According to the current solution method of reradiation interference protecting distance between radio station and UHV power lines, the resonance characteristics of interference is a key issue in decreasing the protecting distance. The wire-surface simulation model, in which steel tower is represented as surface model and ground wire is represented as wire model, is excitated by vertical polarization...
This article discusses different models of the asynchronous generator squirrel cage used in stability studies. The dynamic behavior of a wind farm is shown by using squirrel cage induction generators. Two dynamic equivalent wind farms are analyzed. The park consists of 37 generators, each generator contains a capacitive reactive power at its terminals. We present simulation results.
In order to suppress random pulse interference in field detection of partial discharge in power equipments, pulse features is extracted using equivalent time-frequency analysis. Based on adaptive fuzzy clustering of the features, concentration degree of phases is used as the indicator to distinguish partial discharge signal from pulse interference. The results of field data analysis indicate that...
In this study, mechanical analysis was conducted on the icing load of transmission lines, and the calculation method for the icing thickness was discussed. The icing monitoring system has been developed, based on the measurement of some meteorological information, including wind speed and direction, temperature and humidity, etc and axial tension of overhead transmission line, two-dimensional obliquity...
The short-term unit commitment (UC) problem in thermal power generation is a large-scale, mixed-integer nonlinear programming problem, which is difficult to be solved efficiently. It is possible to approximate the non-linear objective by means of piece-wise linear functions, so that UC can be approximated by a mixed-integer linear programming (MILP). This paper presents tighter constraints for the...
The wind power prediction has great significance on the optimization of grid scheduling, ensuring the power balance and safe operation. First, the ARMA model, the gray prediction model, and the BP neural network model are established by using the sampling time of 15 min wind power time series. The conclusion is that the BP neural network model predicts most accurate. Then, stand-alone wind power and...
Multi-terminal HVDC has been taken seriously for its economical and technological advantages. However, MTDC meets a bottleneck that the VSC, based on IGBT, is destructively vulnerable to the fault on DC side. Consequently How to fast detect and precisely locate them weighs much in MTDC fault clearing. A method combining wavelet analysis and travelling wave is proposed in this paper. We use wavelet...
The Permanent Magnet Synchronous Motor (PMSM), which has high efficiency, high power density and good timing performance, becomes the first choice for the EV drive motor. The vector control system of PMSM used to drive EV is studied in this paper. Firstly, the mathematical model of PMSM vector control and coordinate transformation is analyzed. Secondly, a simulation model based on MATLAB/Simulink...
This paper presents a data refinement process for fault data recorded by a group of associated digital fault recorders (DFR) for improving accuracy in line fault location in a transmission system. The refinement process employs weighted least square state estimation technique to compute calibration factors, using the measurements of pre-fault data of voltage and current from multiple correlated DFRs...
As is known, there exist usually unreliable factors in open communication links, such as time delays and communication failures. When open communication infrastructures are embedded into modern power system to support vast amounts of data exchange, it becomes more challenging to keep the complex power system reliable and stable. In this paper, the modeling and robust controller design problems of...
The Internet of Things for Building Electrical Equipments (IOTBEE), which introduces the Internet of Things (IOT) technology to manage and control all kinds of building electrical equipments, establishes an efficient way for energy-saving in intelligent buildings. However, most of the electrical equipments do not have controllers suitable for communication with the IOTBEE. To realize the control of...
This paper introduced a method of converting AC transmission lines to tripole DC using current modulation. This method cannot only make full use of existing lines and equipment, but also improve power capacity and system performance. So it is available in both technology and economy. This paper also analyzed the principles of current modulation. Moreover, tripole DC transmission system is simulated...
VSC-HVDC (Voltage Source Converter High Voltage Direct Current) transmission system is a recent HVDC technology. The paper presents a new way of VSC-HVDC electromechanical transient modeling and simulation, which is based on the theory of equivalent sources. This method uses equivalent sources to substitute for voltage source converter, in addition, there are no simulation of IGBTs or PWM trigger...
Aiming at the development of solar light monitoring system in China, and combining Zigbee and GPRS technology, a monitoring system for solar light has been designed and realized in this paper. The system is mainly composed of four parts: road lamp control unit, ZigBee module, GPRS module, and monitoring and managing software. The street light unit is applied to collect state information, ZigBee module...
In order to improve accuracy of load forecasting for power grid, since the load characteristics of Yichang power grid is sensitive to climate impact, an Elman neural network (NN)-based short-term load forecasting model under comprehensive consideration of various meteorological factors is established. Elman NN has a dynamic recurrent performance which is able to enhance the adaptability of forecasting...
According to statistics, the low-voltage arc fault has become one of the primary factors leading to electrical fires. It's the fact that traditional circuit protecting devices cannot detect arc fault effectively. Therefore, there are great practical significance and prospect of application in research on arc fault detecting technology. In this paper, the identification method for arc fault based on...
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