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Le Y.,State Grid Corporation of China | Le Y.,Zhejiang Zhoushan Marine Power Research Institute Co. | Xuan Y.,State Grid Corporation of China | Xuan Y.,Zhejiang Zhoushan Marine Power Research Institute Co. | And 7 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2015

In lightning impulse tests for DC cables, the measured voltage waveform has abnormal jitter and does not accord with the standards. To solve this problem, we theoretically analyzed the impulse test discharge circuit with its impulse voltage generator connecting firstly to the voltage divider and then to the test object (defined as "Way I"). We also simulated the circuit in Way I in Pspice, and compared and simulated the waveforms obtained from the capacitive voltage divider and the test object. The analysis indicates that the lead inductance between the capacitive voltage and the test cable leads to the deviance of the measured waveform from the actual waveform or even the abnormal jitter, if the lead inductance is large enough. Hence, we proposed a circuit that has the impulse voltage generator connected first to test object and then to voltage divider (defined as "Way II"). To verify Way II, using various lead inductances, we compared the coincidence degree between the measured waveforms using the two circuits and the actual waveform, as well as the measuring error of some time parameters (front time, time to half-value). The result indicates that using Way I, with increasing lead inductance, the measured waveform deviation, the amplitude of abnormal jitter, and the measuring error of time parameters all increases. However, using Way II, even with a relatively high lead inductance, the measured waveform has no abnormal jitter and it is nearly consistent with the actual one, while the measuring error is small. In addition, we conducted the experimental lightning impulse tests using Way II. The obtained test waveform has no abnormal jitter and it is consistent with the simulation result. ©, 2015, Science Press. All right reserved.


Zhang L.,State Grid Corporation of China | Zhang L.,Zhejiang Zhoushan Marine Power Research Institute Co. | Yu E.,State Grid Corporation of China | Chen G.,State Grid Corporation of China | And 3 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2015

The loss of lead sheath and armor in long distance single-core submarine cable would lower the ampacity even cause the electrical fault of the cable. To solve the problem, we proposed two solutions, namely replacing the steel wire armour by aluminum wire armour (which has smaller relative permeability) and stringing resistances in lead sheath and armour circuit. Based on theoretical analysis, a thermal cycling test system of submarine cable in shore environment was designed and used to conduct a series of comparative experiments for 110 kV single-core submarine cables, including mutual inductance tests, loss tests, temperature rise tests and so on. The principle and effect of the methods in reducing the cable loss, protecting the cable and upgrading the ampacity were explored and verified. The results show that the lead covered circulation has a shielding effect on armour layer. Changing armour material and stringing resistances can enhance the submarine cable's ampacity by 24.2% and 9.68%, respectively. ©, 2015, Science Press. All right reserved.


Zhang L.,State Grid Corporation of China | Zhang L.,Zhejiang Zhoushan Marine Power Research Institute Co. | Xuan Y.,State Grid Corporation of China | Le Y.,State Grid Corporation of China | And 3 more authors.
Gaoya Dianqi/High Voltage Apparatus | Year: 2016

Due to the unique structure of submarine power cable and its complex laying environment, its ampacity is of difficulty in study. To investigate the electro-thermal properties and the ampacity of the submarine cable, this study used three methods to analyze and calculate the ampacity of typical submarine cable. The losses of the armor and lead sheath, which are specially for submarine cable, were analyzed, and the methods for calculating the thermal coefficient and ampacity were provided. Taking the typical HJQF41 64/110 kV 1×500 submarine cable for example, its ampacity under different laying conditions and ambient temperatures was calculated. Moreover, the finite element analysis software Comsol was adopted to simulate the temperature field of the cable, and a thermal cycling test system with beach environment was designed to test the ampacity of the submarine cable. The three methods were compared in their performances, and they were demonstrated to be feasible for investigating ampacity of submarine cable. © 2016, Xi'an High Voltage Apparatus Research Institute Co., Ltd. All right reserved.

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