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Zhao Y.,Chongqing University | Wei Y.,Wenzhou Power Supply Company | Fan F.,Chongqing University | Xiong X.,Chongqing University | Mao Y.,Wenzhou Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2015

The fretting between wires of transmission lines caused by long-term wind-induced vibration results in rupture of wires easily. The impact of strong wind and rain loads exacerbates the risk, which results in a significant increase in broken strand and broken lines. It's necessary to study reliability modeling of transmission lines which bears long-term fretting under the impact of strong wind and rain loads. According to theoretical models of fretting, the time-varying structural strength model of aluminium conductor steel reinforced (ACSR) is built up, the contact stress between wires is solved. Thereby the time-varying model of structural resistance is built up. According to the joint action of fretting and strong wind and rain loads, the random nature of transmission line strength and permanent load, the time-dependent reliability model of transmission lines are built up. Numerical results show that fretting degrades reliability model and rain load can't be neglected under strong wind and rain condition. Time-dependent failure probability model can be used to perfect forecast the rupture risk of wires and make risk warning under inclement weather. The example results prove that fretting will reduce the structural reliability of the transmission line significantly and the strong wind and rain loads increase the risk of the accident. ©, 2015, Power System Protection and Control Press. All right reserved.


Zhu H.,Wenzhou Power Supply Company | Huang R.,Wenzhou Power Supply Company
Gaoya Dianqi/High Voltage Apparatus | Year: 2014

An incident that the leakage current of metal oxide surge arrester (MOA)is higher than specified value is analyzed. Combination of infrared temperature measurement, on-line monitoring data and climate features, the cause of the above incident is due to surface pollution of MOA. The variation of the testing data caused by surface pollution is analyzed in principle. How to effectively distinguish the feature difference between the surface pollution and MOA fault is pointed out to avoid misjudging the condition of MOA. ©, 2014, Xi'an High Voltage Apparatus Research Institute. All right reserved.


Li T.-Y.,Northeast Dianli University | Yuan M.-Z.,Northeast Dianli University | Li J.-Q.,Wenzhou Power Supply Company | Yuan J.-T.,Wenzhou Power Supply Company | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

A new method for identifying power system low-frequency oscillation modal parameters is proposed based on EMD and SSI towards mechanisms which caused the low frequency oscillation. This method can identify the modal parameters of low-frequency oscillation directly according to measured terminal data. When the system running in normal operation or small disturbance, using SSI can get the weakly damped patterns, frequency, damping and vibration mode directly; when the system running in fault state or abnormal operation, the measured data are filtered and smoothed by using EMD, the corresponding state matrix is identified by SSI, and the above modal parameters of low frequency oscillation are obtained by modal analysis. Both numerical simulations and example analysis indicate that using this method it runs fast and detects accurately. It provides a new idea and method to study low frequency oscillation problem in power systems.


Qian B.F.,Wenzhou Power Supply Company | Lin G.X.,Wenzhou Power Supply Company | Jiang Y.K.,Wenzhou Power Supply Company | Wang R.T.,Wenzhou Power Supply Company
Applied Mechanics and Materials | Year: 2014

Many reasons of low voltage in distribution network of Zhejiang province were investigation owing to many complaints from the areas. Because of a mass of site visits, simulation models were built to prove reasons of low voltage. The reason statistics of the transformer districts over the province list several proportions for the problems. Lastly, five advices were obtained to solution low voltage including planning, design, construction, reactive compensation and remote monitoring. It is helpful for solving the problem pertinently. © (2014) Trans Tech Publications, Switzerland.


Lin G.,Wenzhou Power Supply Company | Qian B.,Wenzhou Power Supply Company | Wang R.,Wenzhou Power Supply Company | Liu X.,Wenzhou Power Supply Company | Wang J.,Wenzhou Power Supply Company
Lecture Notes in Electrical Engineering | Year: 2015

The safe and reliable prejudging device for open circuit in the secondary side of current transformer has been developed. On the basis of explaining the process and defects of the traditional operation, the paper designs a schematic diagram of prejudging device. The suitable values of the shunt resistors have been obtained from lots of calculation and analysis with the safety precaution and approach designed at meanwhile including the components selection and the design optimization. The test results show that the device could well prejudge the circuit open in the in-mending section of the circuit at the secondary side of the current transformer. © Springer International Publishing Switzerland 2015.

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