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Hou H.,Shanghai JiaoTong University | Sheng G.,Shanghai JiaoTong University | Sun Y.,Shandong Liaocheng Power Supply Company | Sun X.,Shandong Liaocheng Power Supply Company | And 2 more authors.
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2014

This paper has analyzed the attenuation characteristics of the electromagnetic fields that the partial discharge radiated, and antenna sensitivity coefficient of the receiving antenna. And as these theoretical bases, this paper proposes a new localization algorithm based on the attenuation model of the electromagnetic fields radiated by partial discharge, which realizes the partial discharge positioning in the substation. This method constructs a 3-D space coordinate system in substation, deduces the relationship between the electromagnetic signal peak the antennas receives and the position of the partial discharge source and the antennas, and lists the equations of the partial discharge position. This algorithm only needs the peak of the signal, and does not need the time-delay of the signals, so the data acquisition system and the processing systems are greatly simplified. Finally, we analyze the electromagnetic wave signals that are obtained from electromagnetic wave simulation software, and tested from simulation of partial discharge signal in laboratory. Using the algorithm to calculate the position of partial discharge electrical source, veracity and feasibility of the algorithm is validated.

Wang Y.,Shandong University | Han X.,Shandong University | Ding Y.,State Grid Corporation of China | Shen J.,Shandong Liaocheng Power Supply Company
Dianwang Jishu/Power System Technology | Year: 2013

In view of the defects in power system reliability analysis that Monte Carlo simulation needs a lot of computational resources and it converges slowly, from the viewpoint of operation and based on Markov chain and under the premise that equipment failure rate complies with exponential distribution characteristics, a model, by which fast analytical analysis on power system operation reliability can be carried out, is proposed. The core of the proposed model lies in following aspects: firstly, a criterion to dividing power system operating conditions into three categories, which can be easily implemented in engineering practice, as well as corresponding state space transition expression are proposed; secondly, based on historical operation data or simulation data of power system, a Markov state transition probability matrix equivalent to power system operation is attained; thirdly, on this basis utilizing state transition probability matrix and current power system operating condition, such reliability indices for some time to come as operation state transition probability, steady state probability and mean time to first failure of power system can be rapidly analyzed to implement rapid assessment of power system operation reliability. Simulation results of RBTS-BUS6 system prove the Markov property of power system state transition and the effectiveness of this research.

Wang W.,North China Electrical Power University | Yue C.,Shandong Liaocheng Power Supply Company | He D.,North China Electrical Power University | Yang K.,North China Electrical Power University | Chen S.,North China Electrical Power University
Science China Technological Sciences | Year: 2014

The shortcomings of oil-immersed transformer solid insulation like low high-temperature resistance of the insulation paper and the uneven distribution of electric field caused by the large difference of dielectric constants between insulation paper and transformer oil, restricted the development of transformer with smaller size and larger capacity. In view of this situation and the transformer's demand for the dielectric physicochemical and mechanical property of insulation material, polycarbonate, polyester film and polyphenylene sulfide with high high-temperature resistance were chosen for the comparison analysis in this paper We did the 300-day thermal aging experiment on four samples in transformer oil under different aging temperatures of 90°C, 110°C and 130°C, then analyzed the changes of their dielectric properties. The experiment results are as follows; the permittivity and dielectric dissipation factor of the three polymer materials are apparently smaller than those of the paper both before and after 300-day aging; the volume resistivity and partial discharge inception voltage of the three materials are higher than those of the paper both before and after aging; and the breakdown field strength of polycarbonate is higher than that of the paper both before and after aging, while that of polyester film and polyphenylene sulfide are slightly lower than that of the paper. © 2014 Science China Press and Springer-Verlag Berlin Heidelberg.

Cai C.,Northeastern University China | Chu F.,Northeastern University China | Wang Z.,Northeastern University China | Jia K.,Shandong Liaocheng Power Supply Company
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

The control system of the permanent magnet synchronous motor (PMSM) has the characteristics of nonlinear and strong coupling. Therefore, In order to improve the control precision, the paper presents a novel approach of speed control for PMSM using adaptive BP (back-propagations)-PID neural network. The approach consists of two parts: on-line identification based on BP neural network and the adaptive PID controller. Lyapunov theory is used to prove the stability of the control scheme. Simulation results show that this control method can improve the dynamical performance and enhance the static precision of the speed system. © 2013 Springer-Verlag Berlin Heidelberg.

Tu Y.,North China Electrical Power University | Sun W.,Yunnan Electric Power Research Institute | Yue C.,Shandong Liaocheng Power Supply Company | Wang W.,North China Electrical Power University | Chen G.,North China Electrical Power University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2013

The dielectric constants and the high temperature resistant performance of solid insulation used in oil-immersed transformer would limit the capacity and size of an oil-immersed transformer. In this paper, 3 polymers(polyester film, polycarbonate and phenylene sulfide) are aged under 130°C up to 1 200 hours. The dielectric spectroscopy(here refers to the change tendency of relative permittivity and tanδ along with the change of temperature) and the AC electric breakdown strength of 3 polymers are investigated at different aging stages. According to the test results, the dielectric constants of three polymers is always less than the dielectric constant of insulating paper/board and more close to that of transformer oil, and their tanδ are also less than that of insulating paper/board. Before aging test, the dielectric constants and tanδ of polyester film and phenylene sulfide would be increased obviously at about 90°C, but not the polycarbonate. There shows the same change tendency of the dielectric constants and tanδ for 3 polymers at different aging stages as without aging test. It is also found that the AC breakdown voltage of 3 polymers at different aging stages have almost kept the same as the value of non-aged state. Considering the dielectric properties of these 3 polymers, comparing the properties of insulating paper/board, in terms of the lower dielectric constant and the higher ac breakdown voltage, polycarbonate may be used as one of suitable replacement materials for insulating paper/board used in oil-immersed transformer.

Wang Z.,Northeastern University China | Shen Z.,Northeastern University China | Cai C.,Northeastern University China | Jia K.,Shandong Liaocheng Power Supply Company
Proceedings of the International Joint Conference on Neural Networks | Year: 2014

Wind turbine generator system(WTGS) is a complex multi varies nonlinear system with the characteristics of time varying, strong coupling and multi interference. Wind speed is affected by many factors, the magnitude and direction are random. There are numerous of factors such as temperature, weather, environment and so on that affect wind turbine generator system, result in the WTGS cannot be guaranteed safety operation and constant output power. With the characteristic of strongly nonlinear, delay and uncertainty, the WTGS cannot be given an ideal control using traditional PID controller. Although the neural network control can solve the problems of nonlinear and uncertainty, it belongs to nonlinear approximation in essentially and cannot eliminate the error in steady state. In order to improve wind turbines behavior, an adaptive control method based on RBF-PID neural network is presented in this paper. This algorithm synthesizes the mechanical and electrical characteristics. System identification is part of the controller. At high wind speed, pitch angle is adjusted to keep rated output power using neural network adaptive controller. The RBFNN is used as the identifier of the WTGS. According to the identification information and the given learning speed, PID parameters are modified on line. The Matlab simulation results at random wind speeds show the controller can effectively improve the performance of variable pitch control. © 2014 IEEE.

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